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This paper presents a methodology for evaluating different flight control actuation system architectures in the early conceptual design phase. In particular, this paper shows how hydraulic and electric actuators can be modeled even if very little is known about the aircraft design or requirements while still including the most dominant static and dynamic characteristics. Singular Value Decomposition is used to estimate model parameters and actuator characteristics from industrial data. This is a quick way to estimate what is needed with little input. The purpose of the models is to predict the power consumption, cooling needs, weight, and size. This is performed by integrating the actuator models in a dynamic simulation framework that also includes a flight simulator and surrounding systems. The results from subsystem studies support the aircraft design process, where actuator characteristics affect the engine performance and aircraft sizing. The methodology is applied to a generic fighter by comparing hydraulic and electric actuation system architectures. Besides providing a generic approach to the actuator modeling, the parameters that affect both the static and dynamic characteristics of an electromechanical and electrohydrostatic actuator are estimated with reasonably good accuracy with only four design parameters as input. [ABSTRACT FROM AUTHOR]

Four-wheel independent drive and four-wheel independent steering (4WID-4WIS) vehicles provide increased redundancy in fault-tolerant control (FTC) schemes, enhancing heterogeneous fault-tolerant capabilities. This paper addresses the challenge of maintaining vehicle safety and maneuverability in the presence of actuator faults in autonomous vehicles, focusing on 4WID-4WIS systems. A novel unified hierarchical active FTC strategy is proposed to handle various actuator failures. The strategy includes an upper-layer motion controller that determines resultant force requirements based on trajectory tracking errors and a middle-layer allocation system that redistributes tire forces to fault-free actuators using fault information. This study, for the first time, considers multi-fault scenarios involving longitudinal and lateral coupling, calculating FTC boundaries for each fault type. Additionally, a fault tolerance index is introduced for 256 fault scenarios, using singular value decomposition to linearly represent the vehicle attainable force domain. Based on this, an adaptive velocity planning strategy is developed to balance safety and maneuverability under fault conditions. Matlab 2021a/Simulink and Carsim 2019 co-simulation results validate the proposed strategies, demonstrating significant improvements in fault-tolerant performance, particularly in complex and emergency scenarios. [ABSTRACT FROM AUTHOR]

Dielectric elastomer actuators (DEAs) are emerging as promising candidates for various applications in robotics and optical devices due to their lightweight, miniaturization potential, high energy density, simple structure, and low power consumption. However, their effective actuation always demands sophisticated high-voltage driving circuits that are compact and responsive. DEAs need to be capable of generating intricate high-voltage waveforms or simultaneously controlling multiple quadrants with distinct high-voltage levels. This paper proposes a high-voltage power supply for DEAs, featuring a four-quadrant high-voltage driving circuit. The circuit is capable of independently generating high-voltage signals ranging from 100 V to 6000 V and producing arbitrary waveforms with adjustable frequencies. The independent operation of the quadrants without crosstalk showcases the system's integration and potential for cross-disciplinary applications. [ABSTRACT FROM AUTHOR]

This article introduces a novel regenerative suspension system designed for active seat suspension, to reduce vibrations while recovering energy. The system employs a four-quadrant electric actuator operation model and utilizes a brushless DC motor as an actuator and an energy harvester. This motor, a permanent magnet synchronous type, transforms DC into three-phase AC power, serving dual purposes of vibration energy recovery and active power generation. The system's advanced vibration control is achieved through the switching of MOSFET transistors, ensuring the suspension system meets operational criteria that contrast with traditional vibro-isolation systems, thereby reducing the negative effects of mechanical vibrations on the human body, while also lowering energy consumption. Comparative studies of the regenerative system dynamics against passive and active systems under random vibrations demonstrated its effectiveness. This research assessed the system's performance through power spectral density and transmissibility functions, highlighting its potential to enhance energy efficiency and the psychophysical well-being of individuals subjected to mechanical vibrations. The effectiveness of the energy regeneration process under the chosen early excitation vibrations was investigated. Measurements of the motor torque in the active mode and during regenerative braking mode, and the corresponding phase currents of the motor, are presented. [ABSTRACT FROM AUTHOR]

This paper proposes the development of an active control system to control the power output of a low-power horizontal-axis wind turbine (HAWT) when operating at wind speeds above the rated wind speed. The system is composed of an active articulated vane (AAV) in charge of the orientation of the wind turbine, which is driven by an electric actuator that changes the angle of the AAV to maintain a constant power output. Compared with the passive power regulation systems most often used in low-power HAWTs, active systems allow for better control and, therefore, greater stability of the delivered power, which reduces the structural stresses and allows for controlled braking in any wind condition or during system failures. The control system was designed and simulated using MATLAB R2022b software, and then built and evaluated under laboratory conditions. For the control design, the transfer function (TF) between the pulse width modulation (PWM) and the AAV angle (θ) was determined via laboratory tests using MATLAB's PIDTurner tool. For the simulation, the relationship between the power output and the AAV angle was determined using the vector decomposition of the wind speed and wind rotor area. Wind speed step and ramp response tests were performed for proportional–integral–derivative (PID) control. The results obtained demonstrate the technical feasibility of this type of control, obtaining settling times (ts) of 6.7 s in the step response and 2.8 s in the ramp response. [ABSTRACT FROM AUTHOR]

Digital twins of industrial and collaborative robots are widely used to evaluate and predict the behavior of manipulators under different control strategies. However, these digital twins often employ simplified mathematical models that do not fully describe their dynamics. In this paper, we present the design of a high-fidelity digital twin of a six degrees-of-freedom articulated robot using Simscape Multibody, a Matlab toolbox that allows the design of robotic manipulators in a rather intuitive and user-friendly manner. This robot digital twin includes joint friction, transmission gears, and electric actuators dynamics. After assessing the dynamic accuracy of the Simscape model, we used it to test a computed torque control scheme, proving that this model can be reliably used in simulations with different aims, such as validating control schemes, evaluating collaborative functions or minimizing power consumption. [ABSTRACT FROM AUTHOR]

Since robotic arms operating close to people are becoming increasingly common, there is a need to better understand how they can be made safe when unintended contact occurs, while still providing the required performance. Several actuators and methods for improving robot safety are studied and compared in this paper. A robotic arm moving its end effector horizontally and colliding with a person's head is simulated. The use of a conventional electric actuator (CEA), series elastic actuator (SEA), pneumatic actuator (PA) and hybrid pneumatic electric actuator (HPEA) with model-based controllers are studied. The addition of a compliant covering to the arm and the use of collision detection and reaction strategies are also studied. The simulations include sensor noise and modeling error to improve their realism. A systematic method for tuning the controllers fairly is proposed. The motion control performance and safety of the robot are quantified using root mean square error (RMSE) between the desired and actual joint angle trajectories and maximum impact force (MIF), respectively. The results show that the RMSE values are similar when the CEA, SEA, and HPEA drive the robot's first joint. Regarding safety, using the PA or HPEA with a compliant covering can reduce the MIF below the safety limit established by the International Organization for Standardization (ISO). To satisfy this ISO safety limit with the CEA and SEA, a collision detection and reaction strategy must be used in addition to the compliant covering. The influences of the compliant covering's stiffness and the detection delay are also studied. [ABSTRACT FROM AUTHOR]

In today's industrial environment, effectively monitoring assets throughout their entire lifetime is essential. Prognostic and Health Management (PHM) is a powerful tool that enables users to achieve this goal. Recently, sensor-equipped actuator electrification has been introduced to capture intrinsic key system variables as time series. This data flow has opened up new possibilities for extracting essential maintenance information. To leverage the full potential of these data, we have developed a novel algorithm for time series registration, which serves as the core of a new similarity-based prognostic method in a PHM context: Partial Time Scaling Invariant Temporal Alignment for Remaining Useful Life Estimation (PARTITA-RULE). Our algorithm transforms acceleration signals into a subset of descriptors for a new actuator, creating a time series. We can extract valuable maintenance information by aligning this time series with the one already labeled from past behaviors of the same actuator's family of heterogeneous sizes and robust scaling factors. The unique aspect of our method is that we do not need to inject prior knowledge for registration intervals at this stage. Once the unknown series is aligned with all possible candidates, we create a weighting scheme to assign a relevance score with an uncertainty measurement for each aligned pair. Finally, we compute interpolants on the Wasserstein space to obtain the asset's Remaining Useful Life (RUL). It is important to note that a relevant result in a PHM context requires a database filled with different labeled system behaviors. To test the effectiveness of our method, we use an industrial data set of vibration signals captured on an aeronautical electric actuator. Our method shows promising Remaining Useful Life (RUL) estimation results even with incomplete time segments. [ABSTRACT FROM AUTHOR]

Digital twins have provided valuable information for making effective decisions to ensure high efficiency in the manufacturing process using virtual models. Consequently, AC electric motors play a pivotal role in this framework, commonly employed as the primary electric actuators within Industry 4.0. In addition, classification systems could be implemented to identify normal and abnormal operating conditions in electric machines. Moreover, the execution of such classification systems in low-cost digital embedded systems is crucial, enabling continuous monitoring of AC electric machines. Self-Organized Maps (SOMs) offer a promising solution for implementing classification systems in low-cost embedded systems due to their ability to reduce system dimensionality and visually represent the model's features, so local digital systems can be used as classification systems. Therefore, this paper aims to investigate the utilization of SOMs for classifying operating conditions in AC electric machines. Furthermore, when integrated into an embedded system, SOMs detect abnormal conditions in AC electric machines. A trained SOM is deployed on a C2000 microcontroller to exemplify the proposed approach. It should be noted that the proposed structure can be adapted for implementation with different systems in the context of Industry 4.0. [ABSTRACT FROM AUTHOR]

With the global attention given to energy issues, the electrification of aviation and the development of more electric aircraft (MEA) have become important trends in the modern aviation industry. The electric actuator plays multiple roles in aircraft such as flight control, making it a crucial technology for MEA. Given the limited space available inside an aircraft, the power density of electric actuators has become a critical design factor. However, the pursuit of high power density results in the need for larger rated power and higher switching frequency, which can lead to severe electromagnetic interference (EMI) issues. This, in turn, poses significant challenges to the overall reliability of the electric actuator. This paper provides a comprehensive review of EMI in high power density motor drive systems for electric actuator systems. Firstly, the state of the art of electric actuator systems are surveyed, pointing out the contradictory relationship between high power density and EMI. Subsequently, various EMI modeling approaches of motor control systems are reviewed. Additionally, the main EMI suppression methods are summarized. Active EMI mitigation methods are emphasized in this paper due to their advantages of higher power density compared with passive EMI filters. Finally, the paper concludes by summarizing the EMI research in motor drive systems and offering the prospects of electric actuators. [ABSTRACT FROM AUTHOR]

The design of a new exoskeleton is presented based on four electric linear actuators for the flexion motion range of the ankle of a user. The exoskeleton system is designed to be easy to operate and fairly inexpensive so that it can be used as a tool for exercising and the rehabilitation of the ankle. A prototype of the ankle exoskeleton is presented with its electrical circuit and components, such as servomotors, microcontrollers, sensors, and power supplies. The prototype is distinguished by an innovative design, which uses linear electric actuators for angular-assisted motion, providing a controlled adaptive movement of the ankle joint in its basic movements, separately and combined. The key elements of the ankle exoskeleton prototype consist of a lower leg housing, front and rear servomotor mounts, and ball joints with the aim of mimicking and supporting the natural movements of the ankle for users with walking and mobility problems. The innovation of the proposed work can be recognized in the portable mechanical design with a proper mechatronic design with four actuators that control ankle motion in all its possibilities. [ABSTRACT FROM AUTHOR]

The purpose of prosthetic devices is to reproduce the angular-torque profile of a healthy human during locomotion. A lightweight and energy-efficient joint is capable of decreasing the peak actuator power and/or power consumption per gait cycle, while adequately meeting profile-matching constraints. The aim of this study was to highlight the dynamic characteristics of a bionic leg with electric actuators with rotational movement. Three-dimensional (3D)-printing technology was used to create the leg, and servomotors were used for the joints. A stepper motor was used for horizontal movement. For better numerical simulation of the printed model, three mechanical tests were carried out (tension, compression, and bending), based on which the main mechanical characteristics necessary for the numerical simulation were obtained. For the experimental model made, the dynamic stresses could be determined, which highlights the fact that, under the conditions given for the experimental model, the prosthesis resists. [ABSTRACT FROM AUTHOR]

Successive years of straw mulching and returning straw to the fields in Northeast China have made strip-tillage necessary, and reasonable strip-tillage operations can create conditions for crop growth. However, there are limited research studies on the related equipment applicable to this area. In this paper, an automatic control strip-tillage machine is designed. According to the conventional planting pattern of maize in this region, the operative processes of the machine were determined, and a suitable strip seedbed structure could then be constructed under straw mulching conditions. The type of coulters and the structural parameters of the V-type soil-crushing wheel were determined through theoretical analysis. Based on the air spring and electric linear actuator, the plowing depth control system and the straw width control system were developed, respectively, so as to improve the stability of the machine operation. Field tests showed that when the forward speed, tillage depth, and theoretical width were 6–12 km/h, 6–12 cm, and 18–24 cm, respectively, the straw clearing rate, soil crushing rate, and tillage depth and breadth stability were higher than 90%, and the soil flatness was less than 2 cm. All the indexes satisfied the agronomic and technological requirements of corn cultivation. The results of this study can provide equipment and technical support for the further popularization of conservation tillage technology. [ABSTRACT FROM AUTHOR]

Recent advances in manufacturing methods have accelerated the exploration of new materials and advantageous shapes that could not be produced by traditional methods. In this context, additive manufacturing is gaining strength among manufacturing methods for its versatility and freedom in the geometries that can be produced. Taking advantage of these possibilities, this research presents a case study involving an electric aerospace actuator manufactured using additive manufacturing. The main objectives of this research work are to assess the feasibility of additively manufacturing electric actuators and to evaluate potential gains in terms of weight, volume, power consumption and cost over conventional manufacturing technologies. To do so and in order to optimise the actuator design, a thorough material study is conducted in which three different magnetic materials are gas-atomised (silicon iron, permendur and supermalloy) and test samples of the most promising materials (silicon iron and permendur) are processed by laser powder bed fusion. The final actuator design is additively manufactured in permendur for the stator and rotor iron parts and in 316L stainless steel for the housing. The electric actuator prototype is tested, showing compliance with design requirements in terms of torque production, power consumption and heating. Finally, a design intended to be manufactured via traditional methods (i.e., punching and stacking for the stator laminations and machining for the housing) is presented and compared to the additively manufactured design. The comparison shows that additive manufacturing is a viable alternative to traditional manufacturing for the application presented, as it highly reduces the weight of the actuator and facilitates the assembly, while the cost difference between the two designs is minimal. [ABSTRACT FROM AUTHOR]

During the operation of boom sprayers in the field, it is crucial to ensure that the entire boom is maintained at an optimal height relative to the ground or crop canopy. Active suspension is usually used to adjust the height. A control system for double-pendulum active suspension was developed in this paper. The control system consisted of a main control node, two distance measurement nodes, a vehicle inclination detection node, and an execution node. Communication between nodes was carried out using a CAN bus. The hardware was selected, and the interface circuits of the sensors and the actuator were designed. The transfer functions of the active suspension and electric linear actuator were established. In order to enhance the efficiency of the control system, the particle swarm optimization (PSO) algorithm was employed to optimize the initial parameters of the fuzzy PID controller. The simulation results demonstrated that the PSO-based fuzzy PID controller exhibited improvements in terms of reduced overshoot and decreased settling time when compared to conventional PID and fuzzy PID controllers. The experimental results showed that the active suspension system equipped with the control system could effectively isolate high-frequency disturbances and follow low-frequency ground undulations, meeting the operational requirements. [ABSTRACT FROM AUTHOR]

Kinematics is a fundamental topic in engineering, robotics, mechatronics, and control systems and significantly resolves some of these fields' most pressing issues. It is essential to assess the balance between a topic's theoretical framework and its empirical validation to succeed in engineering. Educational tools have gained significant attention for their ability to enhance the learning experience by providing the hands-on experiences necessary to assess theoretical frameworks and empirical validations. This paper presents a system incorporating state-of-the-art features, including a fuzzy controller enabling precise control of a linear actuator and a USB camera, to provide an interactive experience. The USB camera captures the position of the actuator, providing real-time visual feedback and allowing the students to validate their theoretical understanding through practical experiments. Precision, accuracy, resolution, and the implementation of the fuzzy controller are measured to evaluate the whole system's performance. The design, implementation, and control of our educational electrical linear actuator for teaching kinematics concepts contribute to a practical educational tool and advance interactive learning approaches in the field. [ABSTRACT FROM AUTHOR]

This paper presents the experimental validation of a Fault-Tolerant Control (FTC) system for Permanent Magnet Synchronous Motor (PMSM) drives, specifically focusing on current sensors. The FTC system is designed to detect and diagnose both single and multiple faults in the current sensors and to reconfigure the control loop to ensure uninterrupted operation in the presence of such faults. Several crucial aspects are addressed in the proposed approach, including fault detection, isolation of faulty sensors, and reconfiguration of the control system through accurate current estimation. To achieve this, a novel adaptation of the Luenberger observer is proposed and employed for estimating the stator currents. The effectiveness of the fault-tolerant control strategy is demonstrated through experimental tests conducted on a 7.2 kW PMSM utilizing a field-oriented vectorial strategy implemented in a dSpace 1104 platform. [ABSTRACT FROM AUTHOR]

Vibration-control techniques generally fall into two categories: passive methods that optimize the structure of the suspension to absorb any impact from the ground, and active methods that directly control the vertical force of the suspension by hydraulic or electric actuators when the vehicle traverses a bumpy road. In this study, a vibration-control method is described that employs both an optimal controller and suspension parameter optimization. Continuous speed bumps are implemented to simulate more complex and realistic driving conditions. First, a vehicle system is modeled using a semi-recursive multibody formulation, which allows for a more precise description of the longitudinal–vertical dynamics. Then, an optimal control method for vehicle vibration control is introduced. Second, the Latin hypercube design is utilized to analyze the response surface methodology (RSM) model. For suspension optimization, the RSM model and the non-linear programming with a quadratic Lagrangian (NLPQL) algorithm are employed. Thirdly, both passive suspension optimization and active motion control are employed for vibration control. The results indicate that the presented method can effectively control vehicle vibration, decreasing the average vibration by 30.8%. The results suggest that the novel approach can also enhance the ride comfort in autonomous vehicles traversing, e.g., a series of speed bumps. [ABSTRACT FROM AUTHOR]

At present, research on intelligent wheelchairs mostly focuses on motion control, while research on attitude-based adjustment is relatively insufficient. The existing methods for adjusting wheelchair posture generally lack collaborative control and good human–machine collaboration. This article proposes an intelligent wheelchair posture-adjustment method based on action intention recognition by studying the relationship between the force changes on the contact surface between the human body and the wheelchair and the action intention. This method is applied to a multi-part adjustable electric wheelchair, which is equipped with multiple force sensors to collect pressure information from various parts of the passenger's body. The upper level of the system converts the pressure data into the form of a pressure distribution map, extracts the shape features using the VIT deep learning model, identifies and classifies them, and ultimately identifies the action intentions of the passengers. Based on different action intentions, the electric actuator is controlled to adjust the wheelchair posture. After testing, this method can effectively collect the body pressure data of passengers, with an accuracy of over 95% for the three common intentions of lying down, sitting up, and standing up. The wheelchair can adjust its posture based on the recognition results. By adjusting the wheelchair posture through this method, users do not need to wear additional equipment and are less affected by the external environment. The target function can be achieved with simple learning, which has good human–machine collaboration and can solve the problem of some people having difficulty adjusting the wheelchair posture independently during wheelchair use. [ABSTRACT FROM AUTHOR]

Underwater pressure-bearing structures are produced in practice by means of pressure self-enhancement methods in order to improve the stress distribution and enhance the pressure-bearing performance. On the other hand, the pairs equation shows that stress is an important factor influencing the degradation of the structure. In fact, improving the stress distribution will not only improve the pressure-bearing performance, but will have an impact on the life degradation trend. Thus, pressure self-enhancement affects the structural life by changing the stress distribution. With this in mind, this paper considers the effect of pressure self-enhancement on the service time of subsea structures, and a Bayesian network (BN)-based method that can be used to predict the remaining useful life (RUL) of underwater self-enhanced structures is proposed. The method also takes into account the influence of multiple sources of structural factors in order to predict the RUL of the structure more accurately. The life degradation process of an all-electric Christmas tree valve actuator is used as a case study. The prediction results are compared with data in the literature to verify the validity of the method. The results have implications for guidance on the O&M assurance of underwater production systems. [ABSTRACT FROM AUTHOR]

The use of agricultural tractors is a major concern in agriculture safety due to the high level of risk of loss of stability combined with the frequent absence of passive safety devices such as rollover protective structures (ROPSs). Indeed, although in most cases the ROPS is installed, when working in vineyards, orchards, or in other cases of limited crop height, the tractor is usually equipped with a foldable ROPS (FROPS), which is often misused because the effort needed for raising/lowering is excessive and the locking procedure is time-consuming. Thus, the goal of this research is to investigate the problem from the ergonomics point of view, developing a support system capable of facilitating FROPS operations. The research outcome consists of the development of a retrofitted full assistance system (FAS) for lowering/raising the FROPS by means of electric actuators. Additionally, an automatic locking device (ALD) was also developed to safely and automatically lock the FROPS. Both the FAS and ALD systems were implemented following a reverse-engineering approach, while their final validation was performed by means of a real prototype tested in a laboratory. The results achieved can contribute to expanding knowledge on human-centered research to improve safety in agriculture and thus social issues of sustainable agricultural systems. [ABSTRACT FROM AUTHOR]

The non-return mechanism is the key device that plays the role of braking in the opening-and-closing electric actuator of an amphibious aircraft hatch door. The ball-and-socket contact pair, providing the pressing force, and the multi-disc friction pair, supplying the braking torque, are two core components in the non-return mechanism. In this paper, the dynamic model of the non-return mechanism is established considering the freedom of rotation-translation. Based on MATLAB/Simulink, the solution framework of the overall dynamic model is built. The dynamic response characteristics of the non-return mechanism in the process of reverse load braking, forward load braking, and continuous closing are analyzed. The braking time and the angular displacement of the output shaft in the braking phase have been presented. Compared with forward load braking, reverse load braking has a longer braking time and smaller angular displacement of the output shaft. In addition, the compaction function of the ball-and-socket contact pair is verified by experiment, and the influence of the cone angle, distribution radius of the ball socket, and the steel ball diameter on the pressing force has been discussed. This study provides a theoretical basis and parametric design platform for the design and optimization of non-return mechanisms, which can shorten the product development time. [ABSTRACT FROM AUTHOR]

This paper addresses the issue of the verification and comparison of the selected properties of a newly developed electric actuator. This actuator is intended to act as the drive of a walking robot designed for robotic football. Its envisioned placement is inside the robot's knee joint and in its upper part. An integral part of the actuator is a harmonic precision gearbox and an absolute rotation sensor. The prototype of the newly developed actuator consists of both aluminum and 3D-printed parts. The selected parameters were verified according to the selected characteristics of ISO standard 9283, namely a one-directional pose accuracy and repeatable pose accuracy. The obtained data were compared with those of the standard actuator used thus far in constructing robots for robotic football. The implemented verification is based on the need to improve the performance parameters of the actuator while ensuring the sufficient accuracy of stopping the actuator in the required position. This is ensured by the use of a more accurate harmonic reducer and rotation sensor compared to the standard actuator. [ABSTRACT FROM AUTHOR]

Constant monitoring of driving conditions and observation of the surrounding area are essential for achieving reliable, high-quality autonomous driving. This requires more reliable sensors and actuators, as there is always the potential that sensors and actuators will fail under real-world conditions. The sensitive condition-monitoring methods of sensors and actuators should be used to improve the reliability of the sensors and actuators. They should be able to detect and isolate the abnormal situations of faulty sensors and actuators. In this paper, a developed model-based method for condition monitoring of the sensors and actuators in an electric vehicle is presented that can determine whether a sensor has a fault and further reconfigure the sensor signal, as well as detect the abnormal behavior of the actuators with the reconfigured sensor signals. Through the simulation data obtained by the vehicle model in complex road conditions, it is proved that the method is effective for the state detection of sensors and actuators. [ABSTRACT FROM AUTHOR]

The paper presents an experimental implementation of an optimal-based vibration control for a scaled wind turbine tower-nacelle structure. A laboratory model of the approximate power scale of 340 W, equipped with a nonlinear tuned vibration absorber (TVA), is analysed. For control purposes, a combined operation of a small-scale electric servo drive and a magnetorheological (MR) damper is used in the TVA system. Nonlinearities of both the electric drive and the MR damper are intrinsic parts of the adopted nonlinear control concept. The aim of the research is the simple-hardware real-time implementation and the experimental investigation of the simultaneous actuator and damper control, including the analysis of the influence of optimal control law parameters and quality function weights on the vibration attenuation efficiency and actuator energy demand. As a reference, an optimal-based, modified ground-hook control with the single goal of the primary structure deflection minimisation is used along with the passive system with zero MR damper current and idling electric actuator, proving the advantages of the proposed method. The regarded solutions guarantee 57% maximum structure deflection reduction concerning the passive TVA configuration, using an MR damper of 32 N maximum force and an electric drive of 12.5 N nominal force and 0.76 W nominal power. An interesting alternative is the optimal control concept tuned with regard to the actuator power minimisation—it provides 30% maximum structure deflection attenuation (concerning the passive TVA configuration) while using a passive damper of 3.3 N maximum force and an actuator of 0.17 W nominal power only. It makes evident the advantage of the properly tuned optimal control algorithm over the modified ground-hook law—it requires 51% less actuator energy than the latter parametrised to exhibit the same vibration attenuation properties. [ABSTRACT FROM AUTHOR]

The conventional electric loader uses a motor instead of an engine, which aligns with the current energy-saving and emission-reduction trend. However, the motor's speed control performance and overload capacity are under-utilized, and the actuator suffers from the potential energy waste problem of the boom arm. This study proposes a variable pressure margin energy recovery system for the electric loader actuator. It uses a combination of a permanent magnet synchronous motor (PMSM) and a quantitative pump. It can achieve variable pressure margin control and energy recovery through the pressure feedback closed-loop control. AMESim is used to build the simulation model based on the system control strategy, actuator, supercapacitor, and PMSM mathematical mode. Under typical working conditions, the simulation study is conducted on a 50-type wheel loader to obtain cylinder displacement, system energy recovery, and energy-saving performance. The simulation results show that the system is feasible and can effectively reduce energy consumption. Its energy recovery efficiency is 65.4%. The PMSM energy supply is reduced by 28.6% with the variable pressure margin control. It has high energy-saving performance, and the energy-saving efficiency is 38.5%. It provides a reference for research on energy-saving systems for electric construction machinery. [ABSTRACT FROM AUTHOR]

Actuator, mostly valve, wearing is an important factor of the overall industrial control system operational cost. Actuator operational wear strongly depends on its operation. Highly utilized elements have a tendency to degrade faster. Therefore, the maintenance teams prefer to minimize their moves. In contrary, control engineers need the actuators to actively operate in their control loops to mitigate disturbances and follow the desired trajectories. Higher control performance is often achieved with an active use of actuators. Control loop quality depends on the controller setup and loop auxiliary functionality. Properly designed filtering not only facilitates controller action, but also impacts actuator operational wear. Industrial control templates are built using the blockware that is embedded in the existing control system. Distributed control system (DCS) and programmable logic controller (PLC) have a limited number of control algorithms. An engineer has to design the control structure and the associated sensor noise filtering using available functionality. This paper evaluates and measures the impact of noise filtering on the loop performance and on the actuator weariness. Relations between noise filtering time constant, loop performance and valve travel deliver recommendations for control engineers. [ABSTRACT FROM AUTHOR]

Deformable mirrors enable the control of wave fronts for the compensation of aberrations in optical systems and/or for beam scanning. Manufacturers of deformable mirrors typically provide calibration data that encode for the fabrication tolerances among the actuators and mirror segments to support open-loop control with high wave front fidelity and accuracy. We report a calibration method that enables users of the deformable mirrors to measure the response of the mirror itself to validate and improve the calibration data. For this purpose, an imaging off-axis Michelson interferometer was built that allowed measuring the mirror topography with high accuracy and sufficient spatial resolution. By calibrating each actuator over its entire range, the open-loop performance for our deformable mirror was improved. [ABSTRACT FROM AUTHOR]

In this article, a Riga plate is exhibited with an electric magnetization actuator consisting of permanent magnets and electrodes assembled alternatively. This exhibition produces electromagnetic hydrodynamic phenomena over a fluid flow. A new study model is formed with the Sutterby nanofluid flow through the Riga plate, which is crucial to the structure of several industrial and entering advancements, including thermal nuclear reactors, flow metres and nuclear reactor design. This article addresses the entropy analysis of Sutterby nanofluid flow over the Riga plate. The Cattaneo–Christov heat and mass flux were used to examine the behaviour of heat and mass relaxation time. The bioconvective motile microorganisms and nanoparticles are taken into consideration. The system of equations for the current flow problems is converted from a highly non-linear partial system to an ordinary system through an appropriate transformation. The effect of the obtained variables on velocity, temperature, concentration and motile microorganism distributions are elaborated through the plots in detail. Further, the velocity distribution is enhanced for a greater Deborah number value and it is reduced for a higher Reynolds number for the two cases of pseudoplastic and dilatant flows. Microorganism distribution decreases with the increased magnitude of Peclet number, Bioconvection Lewis number and microorganism concentration difference number. Two types of graphical outputs are presented for the Sutterby fluid parameter (β = −2.5, β = 2.5). Finally, the validation of the present model is achieved with the previously available literature. [ABSTRACT FROM AUTHOR]

In this article, a Riga plate is exhibited with an electric magnetization actuator consisting of permanent magnets and electrodes assembled alternatively. This Riga plate creates an electric and magnetic field, where a transverse Lorentz force is generated that contributes to the flow along the plate. A new study field has been created by Sutterby nanofluid flows down the Riga plate, which is crucial to the creation of several industrial advancements, including thermal nuclear reactors, flow metres, and nuclear reactor design. This article addresses the second law analysis of MHD Sutter by nanofluid over a stretching sheet with the Riga plate. The Cattaneo–Christov Double Diffusion heat and mass flux have been created to examine the behaviour of relaxation time. The bioconvection of motile microorganisms and chemical reactions are taken into consideration. Similarity transformations are used to make the governing equations non-dimensional ordinary differential equations (ODE's) that are subsequently solved through an efficient and powerful analytic technique, the homotopy analysis method (HAM). The effect of pertained variables on velocity, temperature, concentration, and motile microorganism distributions are elaborated through the plot in detail. Further, the velocity distribution enhances and reduces for greater value Deborah number and Reynold number for the two cases of pseudoplastic and dilatant flow. Microorganism distribution decreases with the augmented magnitude of Peclet number (P e) , Bioconvection Lewis number (L b) , and microorganism concentration difference number (ϖ) . The entropy production distribution is increased for the greater estimations of the Reynolds number (Re L) and Brinkman parameter (B r) . Two sets of graphical outputs are presented for the Sutterby fluid parameter. Finally, for the justification of these outcomes, tables of comparison are made with various variables. [ABSTRACT FROM AUTHOR]

Featured Application: Low-cost flight simulators with electric rotary actuators and optimized geometry for flight simulation. Designing the motion platform for the flight simulator is closely coupled with the particular aircraft's flight envelope. While in training, the pilot on the motion platform has to experience the same feeling as in the aircraft. That means that flight simulators need to simulate all flight cases and forces acting upon the pilot during flight. Among many existing mechanisms, parallel mechanisms based on the Stewart platform are suitable because they have six degrees of freedom. In this paper, a real coded mixed integer genetic algorithm (RCMIGA) is applied for geometry optimization of the Stewart platform with rotary actuators (6-RUS) to design a mechanism with appropriate physical limitations of workspace and motion performances. The chosen algorithm proved that it can find the best global solution with all imposed constraints. At the same time, the obtained geometry can be manufactured because integer solutions can be mapped to available discrete values. Geometry is defined with a minimum number of parameters that fully define the mechanism with all constraints. These geometric parameters are then optimized to obtain custom-tailored geometry for aircraft flight simulation. [ABSTRACT FROM AUTHOR]

Linear actuators are widely used in all kinds of industrial applications due to being devices that convert the rotation motion of motors into linear or straight traction/thrust motion. These actuators are ideal for all types of applications where inclination, lifting, traction, or thrust is required under heavy loads, such as wheelchairs, medical beds, and lifting tables. Due to the remarkable ability to exert forces and good precision, they are used classic control systems and controls of high-order. Still, they present difficulties in changing their dynamics and are designed for a range of disturbances. Therefore, in this paper, we present the study of an electric linear actuator. We analyze the positioning in real-time and attack the sudden changes of loads and limitation range by the control. It uses a general-purpose control with self-tuning gains, which can deal with the essential uncertainties of the actuator and suppress disturbances, as they can change their weights to interact with changing systems. The neural network combined with PID control compensates the simplicity of this type of control with artificial intelligence, making it robust to drastic changes in its parameters. Unlike other similar works, this research proposes an online training network with an advantage over typical neural self-adjustment systems. All of this can also be dispensed with the engine model for its operation. The results obtained show a decrease of 42 % in the root mean square error (RMSE) during trajectory tracking and saving in energy consumption by 25 % . The results were obtained both in simulation and in real tests. [ABSTRACT FROM AUTHOR]

Modern road vehicles are more and more often being equipped with electric actuators. These are intended to play critical roles in passengers comfort and safety. Among the electrified components onboard road vehicles, one can distinguish electric power steering (EPS) systems, which have been the subject of intensive investigations covering both design and control aspects. The abilities of several AC motor topologies to fulfil the EPS systems' requirements have been assessed by a large scientific community in both academia and industry. The present work was aimed at the prediction of the electromagnetic features of the flux-switching permanent magnet machines (FSPMMs), with an emphasis on the air gap flux density. The latter was firstly formulated while neglecting the slotting effect at both sides of the air gap. Then, stator and rotor permeance functions, taking into account the slotting effect and the PM flux concentrating arrangement, were incorporated into the derived flux density spatial repartition. Moreover, the accuracy of the latter was improved through two dedicated correction functions that take into account the rotor position and the magnetic saturation. The last part of the paper presents a simple approach to enhance the developed torque of FSPMMs in an attempt to meet the EPS requirements. [ABSTRACT FROM AUTHOR]

Light electric vehicles are alternative solutions to passenger cars in terms their lower costs and space saving in city traffic. Narrow tilting vehicles (NTV), known also as three–wheeled vehicles, can be equipped with an active tilting stability controller that tilts the vehicle automatically during cornering to enable lateral stability. There are mainly direct tilt control (DTC), steering tilt control (STC), and combined DTC–STC methods described in the literature. The DTC method is typically applied up to 10 km/h vehicle speeds. Considering city traffic and frequent start–stop cycles, the DTC method needs to be improved in terms of lower actuator torque and energy consumption. DTC can be designed by using either hydraulic or servo motor actuators. In state of the art, the servo motor actuator has not been studied in detail considering its integration and application aspects. Mostly, the actuator has been considered as a black box model. Proposed control method in this study enables improvements in the direct tilt control system (DTC) in terms of reducing the actuator peak torque and enables the application of DTC at higher vehicle speeds. Regarding the modeling of the electric actuator, a permanent magnet synchronous motor and field-oriented control model are also included in the simulation model. Modelling of the electric actuator enables accurate representation of actuator dynamics. In this way, battery Ah capacity can be sized and energy consumption of the electric actuator can be calculated for a given drive cycle. To this end, objective of this study is to design a direct tilt control method including the electrical drives and motion control concepts. In this way, an application methodology of the servo motor actuator is developed and implemented on a narrow tilting three-wheeled electric vehicle. Interactions between tilt control system and the servo motor actuator system are described from practical aspects. [ABSTRACT FROM AUTHOR]

This paper presents an electroactive and soft vibrotactile actuator based on a dielectric elastomer. The vibrotactile actuator is composed of an upper layer, an adhesive tape layer, a dielectric layer with bumps, and a lower layer. When a voltage is applied to the actuator, an electrostatic force created between the upper and lower layers pulls the upper layer down, compressing the dielectric layer. As soon as the applied voltage is released, the upper layer is quickly restored to its initial state by the elastic force of the compressed dielectric elastomer. Because two forces contribute to the actuation at the same time, the created vibration is sufficiently strong to stimulate human mechanoreceptors. When the applied voltage is removed, the upper layer and dielectric elastomer return to their initial shapes. We conducted experiments to determine the best weight ratio of polydimethylsiloxane (PDMS) and Ecoflex, and to quantitatively investigate the haptic performance of the proposed vibrotactile actuator. The experiments clearly show that the plasticized vibrotactile actuator can create a variety of haptic sensations over a wide frequency range. [ABSTRACT FROM AUTHOR]

Objective clinical analyses are required to evaluate balance control performance. To this outcome, it is relevant to study experimental protocols and to develop devices that can provide reliable information about the ability of a subject to maintain balance. Whereas most of the applications available in the literature and on the market involve shifting and tilting of the base of support, the system presented in this paper is based on the direct application of an impulsive (short-lasting) force by means of an electromechanical device (named automatic perturbator). The control of such stimulation is rather complex since it requires high dynamics and accuracy. Moreover, the occurrence of several non-linearities, mainly related to the human–machine interaction, signals the necessity for robust control in order to achieve the essential repeatability and reliability. A linear electric motor, in combination with Model Predictive Control, was used to develop an automatic perturbator prototype. A test bench, supported by model simulations, was developed to test the architecture of the perturbation device. The performance of the control logic has been optimized by iterative tuning of the controller parameters, and the resulting behavior of the automatic perturbator is presented. [ABSTRACT FROM AUTHOR]

Landing gear system of an aircraft enables it to take off and land with safety and comfort. Because of the horizontal and vertical velocity of aircraft, upon landing, the complete aircraft undergoes different forcing functions in the form of the impact force that is absorbed by landing gears, shock absorbers, and actuators. In this research, a selection methodology has been proposed for an electrical actuator to be installed in the retraction mechanism of nose landing gear of an aircraft having 1600 kg gross takeoff weight. Nose landing gear and its associated components, like strut and shock absorbers, were modeled in CAD software. Analytical expressions were then developed in order to calculate the actuator stroke, translational velocity, force, and power for complete cycle of retraction, and some were subsequently compared with the computational results that were obtained using MSC ADAMS ® . Air in the oleo-pneumatic shock absorber of nose landing gear was modeled as a nonlinear spring with equivalent spring constant, whereas hydraulic oil was modeled as a nonlinear damper with equivalent damping constant. The nose landing gear system was modeled as a mass-spring-damper system for which a solution for sinusoidal forcing functions is proposed. Finally, an electrical actuator has been selected, which can retract and extend nose landing gear, meeting all of the constraints of aircraft, like fuselage space, aircraft ground clearance, locking loads, power consumption, retraction and extension time, and dynamic response of aircraft. It was found that the selection of an electrical actuator is based upon the quantification of forces transmitted to electrical actuator during one point load at gross takeoff weight. The ability of retraction and extension time, as dictated by Federal Aviation Regulation, has also been given due consideration in the proposed methodology as significant criteria. The proposed system is now in the process of ground testing, followed by flight testing in the near future. [ABSTRACT FROM AUTHOR]

An efficient and all-inclusive health management encompassing condition-based maintenance (CBM) environment plays a pivotal role in enhancing the useful life of mission-critical systems. Leveraging high fidelity digital modelling and simulation, scalable to digital twin (DT) representation, quadruples their performance prediction and health management regime. The work presented in this paper does exactly the same for an electric braking system (EBS) of a more-electric aircraft (MEA) by developing a highly representative digital model of its electro-mechanical actuator (EMA) and integrating it with the digital model of anti-skid braking system (ABS). We have shown how, when supported with more-realistic simulation and the application of a qualitative validation approach, various fault modes (such as open circuit, circuit intermittence, and jamming) are implemented in an EMA digital model, followed by their impact assessment. Substantial performance degradation of an electric braking system is observed along with associated hazards as different fault mode scenarios are introduced into the model. With the subsequent qualitative validation of an EMA digital model, a complete performance as well as reliability profile of an EMA can be built to enable its wider deployment and safe integration with a larger number of aircraft systems to achieve environmentally friendly objectives of the aircraft industry. Most significantly, the qualitative validation provides an efficient method of identifying various fault modes in an EMA through rapid monitoring of associated sensor signals and their comparative analysis. It is envisaged that when applied as an add-on in digital twin environment, it would help enhance its CBM capability and improve the overall health management regime of electric braking systems in more-electric aircraft. [ABSTRACT FROM AUTHOR]

In the flight control system, using an electro-hydrostatic actuator (EHA) instead of the currently used relatively mature electro-hydraulic valve-controlled actuator, there are three prevailing concerns, namely heating, size, and stiffness. This paper proposes a novel principle EHA, called active load-sensitive EHA (ALS-EHA), which can actively realize the adaptive adjustment of pump displacement with load pressure. Its principle analysis and mathematical modeling based on the direct load-sensitive EHA (DLS-EHA) configuration is done to obtain the relationship between motor current and hydraulic reduction ratio. Then, its stiffness characteristics are analyzed, especially the influence of hydraulic reduction ratio on impedance at low frequencies combined with investigating the power matching of ALS-EHA. A comparative experiment between the developed ALS-EHA and the EHA with fixed pump displacement and variable motor speed (EHA-FPVM) was carried out. The results reveal that the proposed ALS-EHA can reduce the motor heating and its displacement tracking error is smaller near zero speed owing to its higher impedance from the lower hydraulic reduction ratio under heavy load conditions. [ABSTRACT FROM AUTHOR]

The all-electric subsea gate valve actuator is one of the critical components of the all-electric subsea production control system. To bridge the gap of the low-power holding mechanism in the all-electric subsea gate valve actuator of the subsea production system, minimize the power consumption and cable number for control and improve the open-position keeping performance of all-electric subsea gate valve actuator, this paper proposed a novel low-power holding mechanism for the all-electric subsea gate valve actuator which can be applied to all-electric subsea gate valve actuators with various valve sizes and process pressure ratings. The proposed low-power holding mechanism uses an electromagnet as a driving element, combines the spiral transmission and the cam-like transmission, and only requires a holding force of approximately 2–7% of the maximum load of the closing spring to keep the valve open. The proposed low-power holding mechanism converts the axial force of the closing spring into the circumferential force, which substantially reduces the output force required for the driving element of the low-power holding mechanism and the number of the actuator's control cables. Analytic models are created for the lockable maximum load of the closing spring and the permissible stroke of the locking tab with regard to the design variables. The parameter effects and the corresponding sensitivities are discussed by numerical analysis. The design parameters and the lockable maximum load of the closing spring of the low-power holding mechanism are obtained. [ABSTRACT FROM AUTHOR]

Featured Application: This work was conducted to develop an automated data acquisition system to monitor the pinch grip in rehabilitation and assessment applications after a stroke. The Upper Extremity Fugl Meyer Assessment (UE-FMA) is the most comprehensive assessment for pinch impairment after stroke. The pinch test of UE-FMA is manually performed by pulling a pincer object away from the patient's fingers while providing a visual observation that results in a subjective assessment. In this study, an automated data acquisition system that consists of a linear electric actuator applying automatic pulling to the customized pincer object held by the volunteer was developed. The pinch force was measured such that a strain gauge was placed on the pincer object while pulling force was measured using pulling force load cell connected in between the linear electric actuator and customized pincer object. The pincer object's slip onset was detected using a displacement slip sensor. The mean pinch and pulling force values at the slip onset were 12.17 and 6.25 N for right hands, while mean pinch and pulling force values were 11.67 and 5.92 N for left hands of 50 healthy volunteers, respectively. Based on the paired t-test, there is no significant difference between right and left hands. The automated data acquisition system can objectively apply a pulling force, detect the slip onset, and measure the pinch and pulling forces. [ABSTRACT FROM AUTHOR]

This study aims to develop and evaluate an automated manual transmission (AMT) for agricultural tractors with high efficiency and high convenience by using electric actuators. An AMT system to control manual-type shuttle gearboxes and transmissions for tractors is developed by adding a shuttle shifting actuator, a clutch actuator, and a control system to a conventional manual transmission (MT). The clutch actuator is designed using an electric motor and a reduction gear. The AMT control system is developed and experimental tests are conducted to evaluate the performance of the AMT. The results of the performance of the actuator position control demonstrate that the shuttle shifting actuator and clutch actuator are controlled appropriately, achieving a maximum overshoot of less than 5% and 0%, a settling time of less than 0.500 s and 1.50 s, and a steady-state error of less than 1% and 1%, respectively. The performance of the automatic forward and reverse control demonstrates a shift control time of less than 2.50 s and target revolutions per minute (RPM) reaching time of less than 3.00 s. Thus, AMT systems for tractors can be easily developed by applying shuttle shifting actuators, clutch actuators, and a control system to conventional manual transmissions. [ABSTRACT FROM AUTHOR]

Laser interferometers can achieve a nanometer-order uncertainty of measurements when their frequencies are locked to the reference frequencies of the atom or molecule transitions. There are three types of displacement-measuring interferometers: homodyne, heterodyne, and frequency modulation (FM) interferometers. Among these types of interferometer, the FM interferometer has many advantageous features. The interference signal is a series of time-dependent harmonics of modulation frequency, so the phase shift can be detected accurately using the synchronous detection method. Moreover, the FM interferometer is the most suitable for combination with a frequency-locked laser because both require frequency modulation. In previous research, low modulation frequencies at some tens of kHz have been used to lock the frequency of laser diodes (LDs). The low modulation frequency for the laser source means that the maximum measurement speed of the FM interferometers is limited. This paper proposes a novel contribution regarding the application of a high-frequency modulation for an LD to improve both the frequency stability of the laser source and the measurement speed of the FM interferometer. The frequency of the LD was locked to an I2 hyperfine component at 1 MHz modulation frequency. A high bandwidth lock-in amplifier was utilized to detect the saturated absorption signals of the I2 hyperfine structure and induce the signal to lock the frequency of the LD. The locked LD was then used for an FM displacement measuring interferometer. Moreover, a suitable modulation amplitude that affected the signal-to-noise ratio of both the I2 absorption signal and the harmonic intensity of the interference signal was determined. In order to verify the measurement resolution of the proposed interferometer, the displacement induced by a piezo electric actuator was concurrently measured by the interferometer and a capacitive sensor. The difference of the displacement results was less than 20 nm. To evaluate the measurement speed, the interferometer was used to measure the axial error of a high-speed spindle at 500 rpm. The main conclusion of this study is that a stable displacement interferometer with high accuracy and a high measurement speed can be achieved using an LD frequency locked to an I2 hyperfine transition at a high modulation frequency. [ABSTRACT FROM AUTHOR]

Camless valvetrains have become a promising direction to improve the performance of internal combustion engines. In this paper, an electric load simulator is proposed to simulate and implement gas force on the exhaust valve for camless valvetrains under semi-physical conditions. According to test data, the 1D gas-dynamic model was established to get boundary conditions and initial values for 3D finite element simulation. The 3D finite element simulation model was solved to obtain the gas force characteristics of the exhaust valve for camless valvetrains. The electromagnetic actuator was designed according to the system scheme and performance requirements of the electric load simulator. The PID (Proportion Integration Differentiation) algorithm was designed to control the output force of the electric load simulator and reproduce the gas force characteristics of the exhaust valve. It was found that the output force of the electric load simulator could follow the variation of the target gas force and meet the performance requirements of the electric load simulator based on simulation results and experimental results. [ABSTRACT FROM AUTHOR]

The paper deals with a key issue, how to limit the hazard and assure reliability, safety and repeatability of operation of selected critical devices protecting electrical power systems. The main research is focused on the incorrect operation of hybrid switches caused by random disturbances of the thyristor gate signals in the electrodynamic drive coil power supply circuit. Firstly, a pilot experiment on the operation of hybrid circuit breaker actuators under random disturbance conditions was carried out and the results are presented. Next, an in-depth operation analysis, based on experimental and simulation research, according to setting conditions of the circuit breaker actuator parameters such as capacitance, voltage and switching time was performed. A simulation study with the use of a field-circumferential model in the Ansys Maxwell program of electrodynamic propulsion of rectilinear motion, which enables energy transfer from the capacitor bank to the actuator coil power supply at selected time intervals, was executed. The study analysed the impact of the discontinuity of energy transfer on the dynamic properties of the actuator and some recommendations for designers and users on how to limit this hazard are formulated. [ABSTRACT FROM AUTHOR]

The remarkable ability of humans to perform jump maneuvers greatly contributes to the improvements of the obstacle negotiation ability of humans. The paper proposes a jumping control scheme for a bipedal robot to perform a high jump. The half-body of the robot is modeled as three planar links and the motion during the launching phase is taken into account. A geometrically simple motion was first conducted through which the gear reduction ratio that matches the maximum motor output for high jumping was selected. Then, the following strategies to further exploit the motor output performance was examined: (1) to set the maximum torque of each joint as the baseline that is explicitly modeled as a piecewise linear function dependent on the joint angular velocity; (2) to exert it with a correction of the joint angular accelerations in order to satisfy some balancing criteria during the motion. The criteria include the location of ZMP (zero moment point) and the torque limit. Using the technique described above, the jumping pattern is pre-calculated to maximize the jump height. Finally, the effectiveness of the proposed method is evaluated through simulations. In the simulation, the bipedal robot model achieved a 0.477-m high jump. [ABSTRACT FROM AUTHOR]

Stretchable nanogenerators that directly generate electricity are promising for a wide range of applications in wearable electronics. However, the stretchability of the devices has been a long-standing challenge. Here we present a newly-designed ultra-stretchable nanogenerator based on fractal-inspired piezoelectric nanofibers and liquid metal electrodes that can withstand strain as large as 200%. The large-scale fractal poly(vinylidene fluoride) (PVDF) micro/nanofibers are fabricated by combination of helix electrohydrodynamic printing (HE-Printing) and buckling-driven self-assembly. HE-Printing exploits "whipping/buckling" instability of electrospinning to deposit serpentine fibers with diverse geometries in a programmable, accurately positioned, and individually-controlled manner. Self-organized buckling utilizes the driven force from the prestrained elastomer to assemble serpentine fibers into ultra-stretchable fractal inspired architecture. The nanogenerator with embedded fractal PVDF fibers and liquid-metal microelectrodes demonstrates high stretchability (>200%) and electricity (currents >200 nA), it can harvest energy from all directions by arbitrary mechanical motion, and the rectified output has been applied to charge the commercial capacitor and drive LEDs, which enables wearable electronics applications in sensing and energy harvesting. [ABSTRACT FROM AUTHOR]

A better understanding of how actuator design supports locomotor function may help develop novel and more functional powered assistive devices or robotic legged systems. Legged robots comprise passive parts (e.g., segments, joints and connections) which are moved in a coordinated manner by actuators. In this study, we propose a novel concept of a hybrid electric-pneumatic actuator (EPA) as an enhanced variable impedance actuator (VIA). EPA is consisted of a pneumatic artificial muscle (PAM) and an electric motor (EM). In contrast to other VIAs, the pneumatic artificial muscle (PAM) within the EPA provides not only adaptable compliance, but also an additional powerful actuator with muscle-like properties, which can be arranged in different combinations (e.g., in series or parallel) to the EM. The novel hybrid actuator shares the advantages of both integrated actuator types combining precise control of EM with compliant energy storage of PAM, which are required for efficient and adjustable locomotion. Experimental and simulation results based on the new dynamic model of PAM support the hypothesis that combination of the two actuators can improve efficiency (energy and peak power) and performance, while does not increase control complexity and weight, considerably. Finally, the experiments on EPA adapted bipedal robot (knee joint of the BioBiped3 robot) show improved efficiency of the actuator at different frequencies. [ABSTRACT FROM AUTHOR]

Moving towards the more electric aircraft (MEA), a hybrid actuator configuration provides an opportunity to introduce electromechanical actuator (EMA) into primary flight control. In the hybrid actuation system (HAS), an electro-hydraulic servo actuator (EHSA) and an EMA operate on the same control surface. In order to solve force fighting problem in HAS, this paper proposes a novel linear extended state observer (LESO)-based motion synchronization control method. To cope with the problem of unavailability of the state signals required by the motion synchronization controller, LESO is designed for EHSA and EMA to observe the state variables. Based on the observed states of LESO, motion synchronization controllers could enable EHSA and EMA to simultaneously track the desired motion trajectories. Additionally, nonlinearities, uncertainties and unknown disturbances as well as the coupling term between EHSA and EMA can be estimated and compensated by using the extended state of the proposed LESO. Finally, comparative simulation results indicate that the proposed LESO-based motion synchronization controller could reduce significant force fighting between EHSA and EMA. [ABSTRACT FROM AUTHOR]

In this paper an adaptive non-singular fast terminal sliding mode (NFTSM) control scheme is proposed to control the electro-mechanical actuator (EMA) in an electric braking system which is a complex electro-mechanical system. In order to realize high-performance brake pressure servo control, a radial basis function (RBF) neural network method is adopted to deal with the difficulty of estimating the upper bound of the compound disturbance in the system, to reduce the conservatism of the design of sliding mode switching gain, and effectively eliminate sliding mode chattering. The simulation results show that, compared with a linear controller, the proposed control strategy is able to improve the servo performance and control precision. In addition the response speed of the braking actuator is enhanced significantly, without changing the traditional double-loop control structure. [ABSTRACT FROM AUTHOR]