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The limited-angle torque motor (LATM) is an electric actuator capable of rotating within a limited angular range and outputting a stable torque. It features a simple structure and high reliability and can be used in precise position or torque control scenarios. To reduce the torque fluctuation within the constant torque range (CTR), the effects of the stator tooth topology and size, PM magnetization direction and size, and sleeve permeability on the torque-angle characteristic of the LATM within the CTR were analyzed through FEM simulation, and the characteristics of the LATM before and after optimization were compared. Furthermore, a magneto-thermal coupling simulation of the steady-state temperature increase and thermal deformation generated by the LATM was conducted to study the effect of temperature on the LATM. The results show that the optimized LATM can output a more stable torque within the CTR and that the rated torque fluctuation rate relative to the torque at the zero position decreases by 3.2%. In addition, the temperature increase and corresponding thermal deformation of the optimized motor at 20 °C decreased by 0.22% and 0.29%, respectively. [ABSTRACT FROM AUTHOR]

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]

As the main prerequisite for flow in microfluidic chips, micropumps have always been the core component of microfluidic systems. With the continuous development trend of the three dimensions and high integration for microfluidic systems in recent years, combining the characteristics of micro and drivable fluid flowing in 3D space is the current mainstream research goal in the functions of the micropumps. Here, based on the continuous electrowetting effect in a confined space of the Ga‐based liquid metal (LM), an LM driving micropump structure is proposed that enables fluid to be pumped up to 200 mm in height, which meets the major demands of microfluidic system working environments. The pumping mechanism is experimentally analyzed and demonstrated, as well as the working performance of the micropump under different output modes (continuous flow and pulsatile flow). The feasibility of this micropump is also verified through a fluid pumping experiment in complex shaped channels and a temperature management experiment in 3D space. This work is envisaged to expand the function and application area of the electric actuators driven by the Ga‐based LM and provide new support for micropumps in the 3D microfluidic chip system. [ABSTRACT FROM AUTHOR]

To the challenges posed by the complex structure and low reliability of existing hydraulic actuators used for more electric aircraft landing gear, this paper proposes an optimised design method for an electric actuator based on the principles of tubular permanent magnet linear motor employing a Halbach array. For this electric actuator, a subdomain model considering the longitudinal end effect is established by setting virtual permanent magnet regions at both ends of the Halbach array. The effectiveness of the proposed method is verified through a comparison with the finite element method. Subsequently, a surrogate model is developed using the proposed subdomain model, and an uncertain optimisation model considering machining and assembly errors is developed based on the interval possibility and the interval order theory. Compared to its initial design, the optimised structure increased the average thrust by 13.4% and reduced the thrust ripple rate by 87.2%, significantly improving the overall performance of the electric actuator. Finally, prototype experiments are carried out to verify the effectiveness of the proposed subdomain method and optimised approach. [ABSTRACT FROM AUTHOR]

Sensorless control of permanent magnet synchronous motor (PMSM) can increase the reliability of electric actuators of more electrical aircraft. Numerical online parameter estimation method will enhance the performance for sensorless control methods based on sliding mode observer (SMO). However, numerical online parameter identification methods typically assume zero rotor position estimation error to ensure full rank of the identification equation set. This assumption actually leads to errors in parameter identification, resulting in steady‐state errors in rotor position estimation. This paper focuses on a compensation method for PMSM online parameter identification that takes into account rotor position estimation error. This method is used for sensorless control based on SMO, using model reference adaptive systems for online parameter identification, and no additional parameter adjustment required. Validation is conducted on a PMSM experimental platform with maximum load of 15kW. The experimental results of 1000 r/min steady state operation proved the effectiveness of the method, and the dynamic experiments with 5 and 15kW loads proved that the method has no significant adverse effect on the system dynamics. [ABSTRACT FROM AUTHOR]

Abstract In this study, task space tracking control of robot manipulators driven by brushless DC (BLDC) motors is considered. Dynamics of actuators are taken into account and the entire electromechanical system (i.e. kinematic, dynamic, and electrical models) is assumed to include parametric/structured uncertainties. A novel adaptive controller is designed and the stability of the closed loop system is ensured via novel Lyapunov type tools. To demonstrate performance and applicability of the proposed method, a simulation study is conducted using the model of a two degree of freedom, planar robotic manipulator driven by BLDC motors.

Abstract The authors propose an analytical modelling approach for the linear transverse flux permanent magnet motor using the magnetic equivalent circuit method. The main focus of this study is to predict the phase flux‐linkage characteristic of the motor. Essential equations required for implementation of the model and how to solve it are described clearly so that someone can use it easily. A typical motor is selected to apply the proposed model and simulation results, including static characteristics of flux‐linkage and thrust, are presented. To validate the developed analytical model, the discussed motor is also analysed with 3D finite element method using MAXWELL software and the obtained simulation results are compared to each other.

This paper focuses on addressing the limitations of existing mechanical weeding methods for corn plants by introducing a spiral tendon-type precision weeding device specifically designed for corn fields. The study encompasses mechanical design and theoretical analysis to determine the overall structure, component parts, application scenarios, operation modes, and working principles of the device. The force applied to the spiral tendon weeding cutter head, a crucial working component of the device, is analyzed, along with its motion characteristics. This analysis allows for the calculation of the force required for the spiral tendon to penetrate the soil, as well as the determination of its trajectory and speed in the soil. The desired motion pattern of the weeding cutter head is considered in determining the contour shape of the inner cylinder track and its cooperation mode with the roller follower. Furthermore, the design and optimization of the circulation groove track are conducted to derive the key parameters of the track. A prototype is then constructed based on the proposed structural design and parameter optimization scheme. Soil bin tests are performed to evaluate the device's performance. The optimal combinations of working parameters are determined as follows: a 70-mm depth of the weeding cutter head into the soil, a movement speed of 80 mm/s, and an output thrust of the electric actuator of 180 N. Under these conditions, the device achieves a weed removal rate exceeding 95% with a 3% wounding rate, demonstrating stable operational performance. [ABSTRACT FROM AUTHOR]

In order to obtain a high-precision pneumatic control system, it is necessary to study the friction force of the cylinder. However, few researchers have considered the cylinder's frictional characteristics at small-displacements. This study investigated the influence of different conditions on the cylinder friction characteristics during the process from static to small-displacement of the pneumatic double O-ring seal. A set of experimental apparatuses controlled by an electric actuator perform a seal ring small-displacement friction test to achieve the goals. The working principle of sealing rings in different deformation stages is expounded. According to experiments, the sealing ring's friction force in small-displacement movement can be separated into tilt, elastic deformation, pre-sliding, and sliding friction stages. Furthermore, the clearance characteristics between the sealing ring and the piston groove are verified, which decreases with the sealing ring thickness. Finally, the friction displacement characteristics of sealing rings under different pressures and materials during the elastic deformation stage were verified. It can be concluded that when the displacement is between 0.05 and 0.25 mm, the friction of the sealing ring is almost linear with the displacement; when the displacement reaches 0.25 mm, with the increase of the displacement, the friction force changes in a similar parabolic manner. This study provides a detailed analysis of the friction characteristics of the seal in different stages of small displacement, which plays an important reference role in overcoming cylinder friction and promotes the development of pneumatic systems in the field of accurate position and speed control. [ABSTRACT FROM AUTHOR]

Bionic robots have great potential in healthcare, rescue, and surveillance. However, most soft actuators can only realize one or two deformation modes, which largely limit the application in complex environments. This study develops electric/Infrared (IR) light/magnetic multi‐field coupling soft actuators by combining liquid crystal elastomers (LCE), liquid metal (LM) and magnetic Ecoflex (Mecoflex). Originated from the synergistic effect of the differed thermal expansion and the liquid crystal phase transition, the actuator can realize outstanding large deformations (bending angle > 300°) at ultra‐low voltages (1.0 V). In addition, by designing the molecular orientation in the LCE layer and programming the magnetization in the Mecoflex layer, the bending or helical bending deformations can be controlled under electric/magnetic and IR light/magnetic coupling actuation. Based on the complex deformation capability, bionic climbing plants and two kinds of quadrupedal robots are developed. With the structural design of the quadrupedal robots, they can flexibly switch deformations to pass through complex environments by controlling the externally applied coupling fields, which demonstrates their broad potential in practical applications. [ABSTRACT FROM AUTHOR]

Myoelectric prosthetic hands and fingers with grasping functions have challenges such as weight, cost, and grasping performance of flexible objects owing to the use of electric actuators. To resolve these problems, we propose a self-powered movable prosthetic finger using pneumatic pressure. This prosthetic finger utilizes the flexion/extension of the remaining finger of the user to drive a wire and flex or extend the finger joints. The use of a tendon (wire) and belt drives reduces the space occupied by the prosthetic finger unit compared with conventional linked prosthetic fingers. Furthermore, a sealed-air bellows is used for the joint for flexible grasping owing to passive variable-compliance and damping, which is impossible with only a tendon drive. These features have resulted in the stable grasping of various objects that are difficult to grasp using prosthetic fingers based on conventional technologies. [ABSTRACT FROM AUTHOR]

In this study, task space tracking control of robot manipulators driven by brushless DC (BLDC) motors is considered. Dynamics of actuators are taken into account and the entire electromechanical system (i.e. kinematic, dynamic, and electrical models) is assumed to include parametric/structured uncertainties. A novel adaptive controller is designed and the stability of the closed loop system is ensured via novel Lyapunov type tools. To demonstrate performance and applicability of the proposed method, a simulation study is conducted using the model of a two degree of freedom, planar robotic manipulator driven by BLDC motors. [ABSTRACT FROM AUTHOR]

Agricultural mechanization although reduces the food demand and supply gap through improved and smart technologies, it also risks the lower‐limb disability of workers due to accidents that restrict them to participate in agricultural operations due to the unavailability of appropriate assistive technologies. The lack of use of ergonomics further minimizes the inclusion of female workers in farming operations. Therefore, this study is focused on the development of a sensor‐based wireless hand control system for tractor clutch and brake operation to assist lower‐limb‐disabled agricultural workers and abled females in tractor operation. Actuation force and speed of conventional clutch and brake pedals were evaluated using an integrated foot transducer and used as a reference for the design of the system (clutch: 92–310 N, 36–43 mm/s; brake: 106–329 N, 57–63 mm/s). The hand control system consists of a transmitter and a receiver node incorporating a single‐board computer, matrix keypad, voltage regulators, relay switches, wireless communication through radio frequency modules, and electric linear actuators connected with the pedals through L‐shaped clips, nuts, bolts, and chains. The response time of the developed system was determined as 100 ms and the stopping distance of the tractor using the hand control system ranged from 44.0 to 190.7 cm at a forward speed of 2.1–7.9 km/h. The ergonomic evaluation measured using the K4b2 oxygen analyzer identified the foot control usage in tractors as high energy consuming (9.7–15.1 kJ/min) compared with the hand control usage (7.3–14.1 kJ/min). Electromyography‐root mean square (EMG‐RMS) of upper limb muscle, extension digitorum was found to be highest (14.76–45.29 µV) and was significantly affected by forward speed, gender, subjects, and type of control (p < 0.01) whereas, EMG‐RMS of other selected upper limb muscles, middle deltoid, flexor carpi radialis, and brachioradialis was not significantly affected by the type of control (foot or hand). Muscle workload of all the muscles was observed within the recommended limit (<30%) during the tractor operation with the developed hand control system. The developed hand control system provides options to bypass foot‐based actuation requirement for lower limb disabled as well as female workers. The novel design requires minimal workplace and operating forces and is inclusive of operator ergonomics. [ABSTRACT FROM AUTHOR]

The authors propose an analytical modelling approach for the linear transverse flux permanent magnet motor using the magnetic equivalent circuit method. The main focus of this study is to predict the phase flux‐linkage characteristic of the motor. Essential equations required for implementation of the model and how to solve it are described clearly so that someone can use it easily. A typical motor is selected to apply the proposed model and simulation results, including static characteristics of flux‐linkage and thrust, are presented. To validate the developed analytical model, the discussed motor is also analysed with 3D finite element method using MAXWELL software and the obtained simulation results are compared to each other. [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]

Copyright of Control Theory & Applications / Kongzhi Lilun Yu Yinyong is the property of Editorial Department of Control Theory & Applications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

To improve the speed of mass transfer, a magnetic suspension platform (MSP) is used to transport the display chips. A novel 6‐DOF MSP is proposed in this paper. An improved Halbach array is used to supply the magnetic flux density. Two types of permanent magnets are utilised in the improved Halbach array. The smaller permanent magnet serves to consolidate the magnetic flux density, thereby enhancing the uniformity of the magnetic field. The finite element method is employed to analyse how variations in angle impact both the strength and uniformity of the magnetic flux density. The results show that the magnetisation direction of 45° is the most effective in terms of improving the uniformity and strength of the magnetic density. Finally, a 6‐DOF MSP prototype is manufactured. A magnetic density measurement experiment and a stable suspension experiment for the actuator are conducted. The results indicate an enhancement in the uniformity of the magnetic field within the air gap. Additionally, the maximum suspension positioning accuracy of the actuator is about 750 nm. [ABSTRACT FROM AUTHOR]

Stepper motors are synchronous electric actuators with incremental displacement that can be controlled in open loop in position or speed. Unfortunately, the rotor oscillations that characterize stepper motors are a major handicap that limits the use of this type of actuator in precision industrial applications and especially in biomedical systems. Improving motor drive performance is challenging due to the presence of uncertainty in system parameters and large load variations. To overcome these problems and the shortcomings of conventional control approaches, a new control concept based on fuzzy logic is developed. To this purpose, this paper proposes a fuzzy logic concept (FLC) for damping rotor oscillations of stepper actuator devoted to an Electrical Syringe Pump application. The FLC membership functions and rules are designed with value normalization that allows the developed controller able to be flexible when applied to a wide range of applications. The proposed FLC is numerically validated. Critical testing scenarios are employed including motor inertia variation, supply voltage variation, fluid friction variation and for different loads. Moreover, thanks to its normalized design, the proposed FLC is not limited to the studied biomedical applications, but can be applied to other application systems. [ABSTRACT FROM AUTHOR]

The Dynamic Weighting Control Allocator (DWCA) was introduced by Sadien et al. (Control Engineering Practice, 2019) to solve the allocation problem raised by the yaw control of an on-ground aircraft. It handles the classical tradeoff between virtual reference inputs realisation and control power minimisation. But it also offers three specific features. First, the actuators reach saturation almost simultaneously, which allows an efficient recovery in case of failure. Then, several industrial requirements are taken into account, such as implementation ease, low computational cost and compatibility with certification constraints. And finally, the actuators can be prioritised, the last ones being used sparingly (to avoid overheating, fatigue, maintenance cost...) only when the virtual reference inputs cannot be realised by the first ones only. But despite its attractiveness, the DWCA is limited to the 1-dimensional case, which means that only one degree of freedom can be controlled. This is not sufficient to deal with today's challenges in the aeronautical and automotive fields, for example, where certain control problems are inherently multi-dimensional. With the progressive advent of autonomous cars, new concepts of light hybrid or electric vehicles are, for example, emerging, where both hydraulic and electric actuators are mounted on each wheel to improve the combined management of speed and steering. In this context, this paper introduces a non-trivial generalisation of the DWCA, which retains the various characteristics and advantages of the initial version and can be used in the multi-dimensional case. [ABSTRACT FROM AUTHOR]

An electric actuator, which integrates power electronics technology, computer technology, sensor technology, and motor technology, is a new on-site terminal control device. Especially with the application of intelligent frequency conversion technology, the same device can have different operating speeds and breaking torques within a certain range. This feature is particularly suitable for different working conditions such as valve opening, closing, and operation. In this way, the product specifications and models are significantly reduced, which is conducive to production and user selection. At present, the prototype's test has been completed, and all performance indicators have met the requirements of industry standards. Some technical indicators have even been improved compared with the same type of products of internationally renowned brands. Therefore,its small batch production is being prepared. [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]

In recent years, much attention has been paid to the development of plasma aerodynamics. Among the main tasks to be solved in this area are an increase in thrust force, induced velocity and efficiency of operation of multi-discharge actuator systems used to control air flows. This work presents the results of experimental studies of the dependencies of the characteristics (thrust force, speed of the created air flow, power consumption) of such systems on the parameters of the power mode (voltage, frequency, pulse front duration) with unipolar high-voltage pulses with a bias voltage and comparison of these characteristics when working with other power modes. • High-voltage power supply system provides DC bias voltage to MAS electrodes in combination with repeated unipolar pulses. • High-voltage power supply system with rectangular voltage pulses for multi-discharge actuator system is created. • Electric discharge and gas dynamic characteristics of MAS under various power supply modes were investigated. • At optimal actuator system power supply modes comparable values of thrust force and airflow rates are achieved. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of Nanjing University of Aeronautics & Astronautics is the property of Editorial Department of Journal of Nanjing University of Aeronautics & Astronautics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

Position-controlled systems driving repetitive tasks are of significant importance in industrial machinery. The electric actuators used in these systems are responsible for a large part of the global energy consumption, indicating that major savings can be made in this field. In this context, motion profile optimization is a very cost-effective solution as it allows for more energy-efficient machines without additional hardware investments or adaptions. In particular, mono-actuated mechanisms with position-dependent system properties have received considerable attention in literature. However, the current state-of-the-art methods often use unbounded design parameters to describe the motion profile. This both increases the computational complexity and hampers the search for a global optimum. In this paper, Chebyshev polynomials are used to describe the motion profile. Moreover, the exact bounds on the Chebyshev design parameters are derived. This both seriously reduces the computational complexity and limits the design space, allowing the application of a global optimizer such as the genetic algorithm. Experiments validate the added value of the chosen approach. In this study, it is found that the energy consumption can be reduced by 62.9% compared to a standard reference motion profile. [ABSTRACT FROM AUTHOR]

This study aims to obtain safe working condition of the electrothermal U-shaped actuator (EUA). The finite difference method is applied for modeling and solving the steady electric-thermal state and maximum temperature of the microactuator. The critical voltages causing beam buckling and overheating phenomena are determined to avoid the axial instability as well as melting deformation of the actuator. The relationships between temperature and the frequency or amplitude of the AC are analyzed. The results showed that the structure and the applied voltage levels have significant influence on the temperature distributions and the value of the stress. It is confirmed that the temperature between 300 to 600 °C is comparatively suitable for microactuator according to theoretical and experimental analysis, and the microactuator is able to provide accurate and stable number of cycles for tens of millions. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Parallel robots have many remarkable advantages over their conventional serial counterparts. Highly accurate positioning capability and high payload-to-weight ratio are among the main ones. The main factor underlying all these advantages is their closed-loop construction. However, this constructional feature also causes a special singularity problem, which constitutes their biggest disadvantage. Characteristic singularities classified as Type II exist inside their workspace, around which the magnitude of the inverse dynamic solution grows unboundedly. This naturally yields the saturation of the actuators and eventually in uncontrollability of the robot. Consequently, the whole workspace becomes impossible to be used. In order to pass through a Type II singularity, the consistency of the motion equations of the robot must be maintained at that singularity. However, any Type II singular configuration can transform into a high-order singularity, which, in order to be passed through, requires additional conditions other than the consistency. Therefore, full utilization of the whole workspace with a minimum number of conditions requires to avoid high-order singularities. The present article contributes to the literature by developing path and trajectory planning principles for preventing a two-degree-of-freedom planar parallel robot with RPRPR structure from experiencing high-order singularities. [ABSTRACT FROM AUTHOR]

In this paper, we propose an inchworm-type soft robot using a self-healing gel as its body and shape-memory alloy (SMA) wires as its actuators. To realize inchworm-like locomotion, two coiled SMA wires are placed in parallel in the gel-fabricated body. The bottom-side wire and the upper-side wire reciprocally bend by applying electric current to the actuators. To realize the self-restoration automatically, the robot consists of a self-healing body equipped with magnets. The paper introduces the structure of the inchworm-shaped robot with its inchworm-like locomotion performance, together with the self-healing function. [ABSTRACT FROM AUTHOR]

For cosmic microwave background (CMB) polarization observations, calibration of detector polarization angles is essential. We have developed a fully remote controlled calibration system with a sparse wire grid that reflects linearly polarized light along the wire direction. The new feature is a remote-controlled system for regular calibration, which has not been possible in sparse wire grid calibrators in past experiments. The remote control can be achieved by two electric linear actuators that load or unload the sparse wire grid into a position centered on the optical axis of a telescope between the calibration time and CMB observation. Furthermore, the sparse wire grid can be rotated by using a motor. A rotary encoder and a gravity sensor are installed on the sparse wire grid to monitor the wire direction. They allow us to achieve detector polarization angle calibration with an expected systematic error of 0.08°. The calibration system will be installed in small-aperture telescopes at Simons Observatory. [ABSTRACT FROM AUTHOR]

Dielectric elastomer actuators (DEAs) are soft, electrically powered actuators that have no discrete moving parts, yet can exhibit large strains (10%–50%) and moderate stress (∼100 kPa). This Tutorial describes the physical basis underlying the operation of DEA's, starting with a simple linear analysis, followed by nonlinear Newtonian and energy approaches necessary to describe large strain characteristics of actuators. These lead to theoretical limits on actuation strains and useful non-dimensional parameters, such as the normalized electric breakdown field. The analyses guide the selection of elastomer materials and compliant electrodes for DEAs. As DEAs operate at high electric fields, this Tutorial describes some of the factors affecting the Weibull distribution of dielectric breakdown, geometrical effects, distinguishing between permanent and "soft" breakdown, as well as "self-clearing" and its relation to proof testing to increase device reliability. New evidence for molecular alignment under an electric field is also presented. In the discussion of compliant electrodes, the rationale for carbon nanotube (CNT) electrodes is presented based on their compliance and ability to maintain their percolative conductivity even when stretched. A procedure for making complaint CNT electrodes is included for those who wish to fabricate their own. Percolative electrodes inevitably give rise to only partial surface coverage and the consequences on actuator performance are introduced. Developments in actuator geometry, including recent 3D printing, are described. The physical basis of versatile and reconfigurable shape-changing actuators, together with their analysis, is presented and illustrated with examples. Finally, prospects for achieving even higher performance DEAs will be discussed. [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]

To expand the inclusiveness of hybrid test platform research, enhance the flexibility of hybrid test platforms using various control strategies, and promote the development of hybrid test techniques, a low-cost user-configurable electric actuator hybrid test platform is established in this paper. This platform can be transferred to other medium or large electric actuator hybrid test platform, the research applications of this platform cannot be limited by their proposed setup. Firstly, the hardware system design including hybrid test facility integrated control system core architecture and all related signal routings are carried out. Then, the improved equivalent force control feedback method based on force-loading control is proposed, and the software system development including hybrid test process control system software and user-configurable STM32 microcontroller (UCSM) software are conducted. Next, the mechanical performance of viscoelastic damper is tested, and the mechanical model parameters of viscoelastic damper are regressed. The accuracy of electric actuator force control (inner control loop), of which the control tasks get executed on the UCSM is verified using the experimental substructure of viscoelastic damper. The hybrid test of viscoelastic damping system verifies the reliability and robustness of hybrid test platform (outer control loop). Finally, the developed hybrid test platform implements various hybrid tests of viscoelastic damping system under broad temperature range and different seismic intensities. The test results reveal the influence of temperature and seismic intensities on the seismic control effect of viscoelastic damper. [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]

In this paper, an electric servo actuator implementation scheme with an energy recovery link is proposed to address the potential energy being wasted when a load falls. The new electric servo actuator recovers the potential energy dissipated during the load-falling progress by using an accumulator. The accumulator can also provide extra thrust when the load is lifted. Moreover, a dynamic model is established based on the theory of power bond graphs to analyze the dynamic and energy consumption characteristics of the new electric servo actuator. The simulation results show that the new electric servo actuator can significantly reduce the required motor power and effectively recover the potential energy of the load. This achievement is very significant for improving the energy efficiency of electric servo actuators and mitigating global warming. In addition, the modeling method used in this paper has important reference significance for the energy consumption analysis of other mechanical systems with complex energy domains. [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]