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In this paper, an obstacle avoidance and target tracking method for both indoor and outdoor mobile robots in dynamic environment is presented, and it aims to enhance autonomous navigation capability of such robots. In the proposed method, image processing and machine-learning approaches are considered. Since obstacles have differences in color and texture and in order to identify non-navigable areas, a monocular onboard camera is used to capture the road lanes by dealing with an image processing technique. The position of the robot with respect to road lane center during navigation is calculated on the basis of a proposed fuzzy logic rules set. In order to provide fast and robust computation, the Haar cascade classifier-based machine-learning technique has been exploited to detect the different sizes and shapes of the obstacles faced by the robot during its movement from source to destination. The dynamic model of a four-wheel mobile robot is initially developed using bond graph theory and then, the proposed obstacle-avoidance strategy is applied. The effectiveness and performance of the proposed method are tested under various simulation and experimentation scenarios. The behavior of the mobile robot for detecting and avoiding static obstacle for single and double road lane change environment is analyzed and discussed.

People with knee disorders often find it difficult to perform common mobility tasks, such as stand–sit–stand motions. High knee torque is required to complete such transitions, as the chances of toppling increase during these motions. Most of the existing conventional approaches, such as wheelchairs and crutches, have failed to provide complete independence to the users. Conversely, contemporary systems like lower body exoskeletons which are bulky, complex, and expensive do not specifically target the knee joint instead of assisting other joints. Hence, there is a need to aid the knee joint using a robotic knee exoskeleton capable of accurately providing the desired knee torque. In the present work, to assist the user in performing the stand–sit–stand motions, an electromyography sensor-based four-bar knee exoskeleton actuated by a linear actuator is proposed. The modeling of the complete exoskeleton is developed using bond graph technique, as the components exist in different energy domains and it is possible to frame a dynamic bond graph model using only kinematic equations. The prototype is fabricated, and experiments are carried out on an artificial limb to prove the efficacy of the design of the current knee exoskeleton. The assistive torque developed by the actuator at the knee joint of the exoskeleton is found to be suitable to assist the wearer. As a result, little effort is required by the wearer for performing the stand–sit–stand motions. The rotation of the thigh link of the developed exoskeleton was found to be suitable for performing the stand–sit–stand activity.

In this paper, a two-directional automated machine with a controller for flat gas metal arc welding is developed for welding along any complex shape. Consistent and uniform weld bead deposition can...

Three different pre-treatment methods, that is, alkali hornification, water hornification, and alkali treatment, are evaluated for the improvement in durability of agave natural fiber-reinforced po...

Gearbox is an indispensable element allied with mechanical industries to fluctuate speed and load in accordance with the requirements. More improvements in its mechanical structure and procedure can increase the efficiency of the industries. For those reasons, the gearbox was designed and manufactured very carefully with the zero tolerance of defects. Gearbox failure can lead to an increase in financial loss and decrease in production strength. Vibration signal analysis is used to monitor the gearbox condition. But, non-stationary properties of vibration signal make this procedure very challenging. Therefore, this paper presents a unique gearbox fault investigation technique based on advanced computational intelligence. Firstly, Time Synchronous Averaging algorithm was used to study the nonstationary properties of the raw vibration signal. Then, nine types of time domain arithmetical features were calculated from the pre-processed TSA vibration signal. After that, the J48 algorithm was used for significant features selection of gearbox fault and Naive Bayes algorithm for features classification of gearbox fault. A computer-aided fault simulator was used for experimental study. MATLAB and WEKA platforms were used for signal processing, features selection, and features classification of the gearbox faults. The performance of the proposed method shows meaningful results for gearbox fault diagnosis.

The hybrid manipulators are always found to be of great use in industries due to the major shortcoming of serial manipulators (lesser accuracy and heavy structure) and parallel manipulators (small workspace). Henceforth, a three-dimensional hybrid manipulator is presented in this paper and this hybrid manipulator connects two parallel manipulators in a serial arrangement. Afterwards, the theory of impedance control with some changes is applied for an operation on a three dimensional L-shaped path having some restrictions imposed on the interactive forces when the manipulator is interacting with an object in its environment along with an approach to eliminate amnesia i.e. difference between the actual trajectory and the command trajectory. The overwhelming controller is used between the actual system and the inverse controller. It is observed from the result that there is always some amnesia during force control and some time is provided before the next phase of force control to remove this difference in trajectory.

Time synchronous averaging (TSA) has been extensively applied for gearbox fault analysis. But it cannot unveil the vibration features precisely in conditions of different speeds and load excitation. This paper presents an improved method which is a combination of Time synchronous averaging (TSA) and Empirical mode decomposition (EMD) to extract the intermittent vibration feature from the oscillated vibration response for the fault diagnosis of the gearbox. In this technique, time-synchronous averaging and empirical mode decomposition is performed on the gearbox vibration response to detect fault features. First, TSA is performed on the gearbox raw vibration response. By applying TSA on raw vibration response, a noiseless vibration response with the power spectrum is produced. Finally, decomposition technique is applied on noiseless vibration response and a sequence of IMFs are produced with the power spectrum to obtain more enhanced and improved mono-component of noiseless regular vibration response. Simulation and Practical investigation of the proposed method show the advantages and effectiveness in extracting faulty vibration feature with different speed and load excitation. An experimental investigation has been carried out on the Machinery Fault Simulator with one healthy and two faulty gearbox conditions i.e., healthy tooth, fragmented tooth and missing tooth under three different speed and load excitation.

Moisture diffusion in fibre matrix composites is one of the significant factors that affect the lives of the composite materials and lead to a decline in their working abilities and degrade their properties. Recently, many researchers have been working on the factors such as fibre volume fraction and fibre orientations that can affect the flow of moisture in composites. In the present study, different modelling techniques (FEM and bond graph) along with experimental work have been performed to validate the best fibre orientation that can delay the moisture ingress as well as reduce the resultant stresses that get developed due to moisture absorption.

The walking mobile robots have several advantages as compared to the wheel mobile robots over uneven terrains. The researchers have done a lot to develop different walking mechanisms for legged robots. Due to merits of legged robots such as scalable design, low payload-to-machine load ratio, bio-inspired locomotion, etc., the researchers have shown a great interest in the walking robots based on the Theo Jansen mechanism. In this paper, the dynamic analysis of a four-legged quadruped robot-based upon Jansen mechanism is proposed. The SimMechanics Toolbox Mathworks software is used for developing the physical modeling of the quadruped robot. Also, the real quadruped robot based on Jansen mechanism is developed and validated with a simulation model for checking the trajectory tracking performance. The proposed model of the quadruped robot is used for the application of obstacle avoidance. The fuzzy logic controller is proposed to detect and avoid the obstacles by the robots. Three Ultrasonic sensors (HC-SR04) are mounted in front of the robot to detect the obstacles. The validation of simulation and experimental results shows the performances of the navigation and obstacle avoidance fuzzy controller.

In this work, a bi-directional automatic movement unit for planar welding is indigenously developed in order to obtain weld with uniform bead width along a desired path. System modeling of ...

Experimental and numerical investigations are performed to assess the durability of Palmyra natural fiber composites under hydrothermal ageing conditions. The effect of alkali and stearic acid pret...

Experimental and numerical investigations are performed to evaluate the mass diffusion in Agave Americana natural fiber composites considering several environmental conditions. The effect of fiber pretreatment by alkaline hornification is analyzed on the moisture uptake behavior of the Agave fiber composites. It was observed that water retention value, which is a measure of affinity towards moisture, reduces with each subsequent hornification cycle. The microstructural investigations were performed to analyze the morphological changes in fiber microfibrils. Composite specimens were subjected to accelerated ageing under water and humidity conditions at controlled temperatures between 0 °C and 75 °C. Composites were weighted periodically and mass gain curves were analyzed. A comparison is drawn between the mass gain behavior of composites fabricated using untreated and alkali hornified Agave fibers. The studies have revealed a clear influence of alkaline hornification on the improvement of the hydrothermal durability of the Agave fibers. The effective moisture diffusivity of the composites is determined using edge correction factors for rectanguloid specimens. Finally, the experimental mass gain is compared with the numerical Fick’s law based finite element (FE) approximations.

In construction industry, the conventional way of construction of buildings is a costly, time consuming and a labour-intensive job. Besides that, many on-site fatalities happen during the construction activity and the climate can delay construction activity. 3-D printer robot resolves all these problems. Also, it can be used for intricate building designs and for construction of buildings in remote locations or in epidemic situations. The objective of the project is to make an autonomous robot for 3-D printing a simple civil structure. Three lead screws will provide the movement in the vertical as well as in horizontal directions and a nozzle connected to the horizontal lead screw will be used for pouring the construction-material layer by layer. Thereafter, structural analysis using Finite Element Method (FEM) has been done on critical parts like lead screw and top plate. Bond graphs for buggy and overall lead screw system have also been used to analyze the response of the system. Furthermore, the wring diagram is also developed and presented in the paper. Future research is required for the development of actual robot for building multi-storied structures, on the design of nozzle and type of material used for pouring.

A personal transporter vehicle, called segway, is based on the stabilization principle of inverted pendulum system. In this work, the bond graph model of segway with PI control is developed. The simulation results for the forward and backward motion of segway are presented as pitch angle, speed of the vehicle with respect to time. For the turning of the vehicle, controller based on Ackermann steering mechanism is adopted to modulate the voltages of two motors. The results of turning motion of the segway are also presented as yaw angle response of main vehicle body. The focus of this paper is to develop the dynamic model and simulate the response of segway using non-model-based control system design. The objective of the work is accomplished by developing the stabilization controller based on PI control scheme using bond graph approach. Also, the swing up controller is developed for nonlinear behaviour of the segway.

Nowadays, the key research area of many researchers is the walking mechanism of the robot as walking robots are used in many areas such as military, exploring new materials in space etc. The legged robots are much more capable to move on any type of terrain as compared to wheel robots. The focus of this work is to modelling, simulation and control a stable walking system for quadruped robot model. The proposed model of the quadruped robot is validated for side ramp walking without falling down due its weight. The PI controller is developed to control the movement of the quadruped during walking on the side ramp, which is not reported in literature. Initially, modelling of quadruped robot is done using bond graph approach and Simmechanics technique. Results from both methods are compared and discussed. The trot gait is considered for stable walking of quadruped robot. The Proportional-Integral (PI) based control scheme is proposed for locomotion of the robot along desired path. Finally, the case study for validation of proposed model is done for side ramp walking of quadruped robot.

The dynamics of the four-cylinder In-line engine is taken into account in this work. Firstly, the motion and thermodynamics equations of the engine model are discussed. The bond graph model of the four-cylinder in-line engine with 1-3-4-2 firing order is developed by using SYMBOLS Shakthi software. The thermodynamic and mechanical phenomena are considered while developing the model of the engine. The various engine characteristics parameters such as crank speed vs. torque developed, speed and acceleration of the crank for different values of J (mass moment of inertia of flywheel), piston stroke length of all cylinders and pressure-volume diagram, etc., are discussed for proposed model of the engine. Also, the piston–cylinder model based on prismatic joint is discussed and its bond graph model is developed.

Legged robots have capability of traversing on any type of terrain with much ease and stability compared to wheeled robots. The legged robots do not have continuous contact with ground, and thus, it is easy to avoid obstacles. The objective of this paper is to model and simulate a walking mechanism for quadruple model that is stable and is able to implement different types of gaits. The stability control of legged robot is of utmost importance as compared to wheeled robot as contact from ground is discontinuous due to lifting and placing of leg. The positing of legs relative to body of robot considerably affects the stability, and also the sequence and timing in which legs are moved and placed play important role in energy efficiency. Here, model of quadruped robot with four legs has been developed using bond graph technique. Results from simulation are discussed. The comparison of different gaits is made for energy efficiency.

Fiber-reinforced polymers (FRPs) are sensitive to moisture diffusion. Deterioration caused by moisture can limit their service lives considerably. In this work, a three-dimensional finite element modeling and analysis framework is presented to investigate the moisture diffusion kinetics inside fiber-reinforced inside polymer matrix composites by considering different angle and cross-ply orientations. A small localized representative volume element considering a few fibers in the neighborhood of three-layer stacks has been analyzed. The emphasis is on the effect of different fiber orientations over moisture saturation time and diffusion-induced stresses. Stresses induced due to moisture diffusion in FRPs are evaluated on the free fiber ends. The numerical results from finite element approximations are compared with theories of composite micromechanics such as rule of mixtures, Halpin–Tsai model and concentric cylinder assemblage framework. It is observed that the orientation of fiber layers can greatly influence the moisture ingress inside the matrix and resulting stresses. At intermediate time durations of moisture progression, the cross-ply orientation had ~ 25% lower weight gain in comparison with the unidirectional ply orientations. The overall von Mises stresses at the fiber matrix interface were also lower in cross-ply orientations by ~ 40% in comparison with the other orientations with similar fiber volume fraction. The three-layered cross-ply, 90/90/90 orientation took almost 50% more time to fully saturate with moisture in comparison with the unidirectional, 0/0/0 orientation. The interpretations from the smaller local microstructural models presented in this work can be extended to study and design the structure scale composite layups for the improved moisture durability.

This work describes design and implementation of a navigation and obstacle avoidance controller using fuzzy logic for four-wheel mobile robot. The main contribution of this paper can be summarized in the fact that single fuzzy logic controller can be used for navigation as well as obstacle avoidance (static, dynamic and both) for dynamic model of four-wheel mobile robot. The bond graph is used to develop the dynamic model of mobile robot and then it is converted into SIMULINK block by using ‘S-function’ directly from SYMBOLS Shakti bond graph software library. The four-wheel mobile robot used in this work is equipped with DC motors, three ultrasonic sensors to measure the distance from the obstacles and optical encoders to provide the current position and speed. The three input membership functions (distance from target, angle and distance from obstacles) and two output membership functions (left wheel voltage and right wheel voltage) are considered in fuzzy logic controller. One hundred and sixty-two sets of rules are considered for motion control of the mobile robot. The different case studies are considered and are simulated using MATLAB-SIMULINK software platform to evaluate the performance of the controller. Simulation results show the performances of the navigation and obstacle avoidance fuzzy controller in terms of minimum travelled path for various cases.

This paper deals with the fault detection, isolation (FDI) and reconfiguration of the locomotion of a bipedal-legged robot. Initially, the planar model of the legged robot in the vertical plane is developed using a bond graph (BG) approach. Then, the planar BG model of the legged robot is extended to the three-dimensional legged robot. Two individual motors are used to actuate the prismatic leg of the robot for locomotion. The BG simulation provides results for straight walking based on an oscillating cylinder mechanism and the turning motion of the legged robot are discussed. The prototype model of the legged robot is also developed and experimentation is done for straight and inclined plane applications. Finally, an FDI technique for the three-dimensional model of a legged robot is developed for the generation of fault indicators (i.e., analytical redundancy relations; ARRs) in the presence of system failure. The ARRs are derived from the BG model of the legged robot during the occurrences of the fault. The experimental results are validated with the simulation results for FDI and reconfiguration when the robot manoeuvres in a U-shaped path. The real-time fault diagnosis and reconfiguration for locomotion of the legged robot is possible with this FDI approach.

Some variation in the topological distribution of fibers inside the matrix phase of fiber reinforced polymers (FRP) is inevitable. Such irregularities can accelerate moisture diffusion and adversely affect the life of FRP. This paper presents a hierarchical technique for characterization of clustered microstructures and their transient moisture diffusion response. The clustering descriptors are derived for different fiber volume fractions (dilute to dense) for the quantitative definition of a given fiber matrix architecture. The metrics are normalized to remove dependence on volume fraction. The microstructures are analyzed for Fickian moisture diffusion. Suggested descriptors show a good correlation with transient diffusion response in relation to saturation time. The results can be used to predict the time-dependent moisture diffusion response of FRPs for any given fiber volume fraction.

Generally, industrial manipulators have parallel architecture but these are not generally used because of small workspace as compared to serial manipulators. The drawbacks of serial manipulators are their low accuracy and less load carrying capacity. Therefore, hybrid manipulators are considered to be useful because they are combination of serial and parallel manipulators. In this paper, a three-dimensional hybrid manipulator with two parallel manipulators serially connected to each other is proposed. The forward and inverse dynamics of the system is modelled with the help of bond graph. Thumb and index finger of a human right hand are considered as hybrid manipulators in this paper. The objective of present work is to track the trajectory by thumb in three-dimensional space while drawing an arc on a white board with the help of a marker pen. At the end, the simulation results and conclusions are given to prove that the response follows the command with negligible error. Hence, this type of hybrid manipulator is suitable to be used in multi-fingered robotic grippers, pick and place operations, moving things etc.

The major reasons of the road accidents are the traffic problem and human erroneous driving. The researchers have started developing self-driving cars to avoid such accidents. In this paper, bicycle vehicle model along with its inverse vehicle dynamic model have been developed to track the predefined path and replace the driver. A bicycle vehicle model using bond graph (BG) is created to avoid single and two obstacles of known different geometry in predefined path. The obstacle avoidance algorithm is developed in the Matlab environment and this consists of combination of line following, tangent bug and wall following algorithm. The trajectory data from the obstacle avoidance controller is fed to the inverse controller of bicycle vehicle model to run the forward model of bicycle vehicle. For the trajectory tracking of bicycle vehicle model, the system inversion is carried out through the bond graph-based overwhelming controller. The simulation results for trajectory tracking of bicycle model is presented for single and two static obstacles with different orientations and shapes, and finally, conclusions are presented to show that response of the forward model follows the command (actual path decided by the obstacle avoidance controller) within the acceptable limits. All the results and simulations are obtained using Matlab and $${Symbols Shakti}^\circledR $$ software (Bond graph software).

The diffusion of moisture is an environmental factor that limits the durability of polymer composites considerably in the wet/moist environments. The present paper examines the diffusion of moisture along and across through the unidirectional natural fiber reinforced polymer matrix composites. A number of three dimensional models with different fiber orientations have been used to analyze moisture diffusion along and across the fibers. Fickian moisture diffusion theory has been used to model the mass transport along the considered composite domains. It is observed that there are several orientation of fiber that can impede the moisture ingress, whereas some of the counterpart configurations do not produce the favorable results and hence those kind of configurations can be avoided. The analysis should be helpful in designing moisture durable fiber matrix architectures.

This paper presents the effect of inter-fiber interaction among the fibers in neighborhood on the overall mechanical behavior of the reinforced polymer composites. The effect of inter-fiber interactions is presented for different classes of microstructures. Cohesive zone model is adopted to simulate the interfacial fiber matrix progressive de-bonding. Different microstructural arrangements are considered to model the transverse loading. The study highlights the role microstructural arrangement plays in the final macroscopic response of composites. The observations should help in designing the fiber matrix microstructures for superior mechanical characteristics.

A mechanistic hydraulic flow model based upon plant physiological behavior is proposed in this work to determine functionality of different plant organs in handling flows of water. The model is dev...

The multi-energy domain dynamic systems are of utmost importance; a number of researchers have carried out their modelling by taking advantage of this concept. The dynamic systems are very complex in nature as the time required for simulation is large and their computations become difficult. Therefore, the model reduction is done such that the dynamics of the systems are preserved and accuracy is maintained. With this, the simulation time and number of calculations are reduced considerably. The contribution of this paper is that modelling of a parallel and hybrid manipulator is done using bond graph modelling technique, and then, their dynamic models are reduced with the eigenvalue sensitivity method for model reduction. This paper attempts to achieve this by mathematically finding the redundant elements, which do not add to the dynamics of the system but increase the calculation time by increasing the complexity of the system. The redundant elements could be neglected, and hence, the complexity reduced without compromising the accuracy. The eigenvalues are calculated from the system matrix, and effect matrices are formed. The row and column based on eigenvalues can be reduced to form a reduced model. The trajectory tracking is done for both the manipulators, and results are presented in this paper for full and reduced models. The comparisons of results for full and reduced models are also given in the form of absolute and percentage errors.

The control of cardiovascular system by autonomic nervous system using model-based analysis is very useful to predict blood flow and blood pressure at different locations of human body. The regulation of cardiovascular system by autonomic nervous system is a very complex mechanism, so, an experimental-based model analysis may prove very helpful in studying and analysing its working properly. In this article, a very basic model of cardiovascular system is presented with blood pressure dynamics studied throughout the body. A new bond graph model of the autonomic nervous system embedded with baroreflex system is also presented. Autonomic regulation of ventricular contractility is represented by means of transfer functions. The results in terms of maximum ventricular elastance ([Formula: see text]) and end systolic pressure are shown for two experiments. Another alternative modelling approach to represent the function of nervous system action in blood pressure regulation in terms of an overwhelming controller has been proposed. This controller overwhelms the system properties and therefore helps in managing the unmodelled parts or properties of a system and makes it impeccable for controlling complex systems. All the results and simulations are obtained using Symbols Shakti® software (Bond graph software).

Stand–sit–stand (STS) motions are the most frequently performed activities of everyday life and require extensive movement of knee joint. People suffering from knee joint disorders face difficulties in performing this motion. The compact knee exoskeleton (KE) has proven to be a viable, less complex, and cheaper alternative to the available entire lower-, upper-, and full-body exoskeletons. With growing number of technical glitches and finite battery life problems, there exist risks of sudden failure of the actuator of KE that could be detrimental for the vulnerable users. To overcome this problem, there is a need to accommodate a backup actuator in KE which can continue providing assistance during movement if the primary actuator ceases to function. This article provides a performance comparison of a four-bar mechanism-driven KE that can accommodate both the linear and the rotary actuators. The modelling and simulation of the system are performed using the bond graph (BG) technique. The results successfully showed that both actuators offered desired ranges of motions needed for STS motion. Furthermore, the knee joint torques developed by the linear and rotary actuators were found to be 40 Nm and 57 Nm, respectively, which corresponds to 60% and 85% of the total torque required by the knee joint to perform STS motions, thereby reducing the user effort to 40% and 15%, respectively. Thus, both actuators are self-capable to provide necessary assistance at the knee joint even if the primary actuator ceases to work due to a sudden fault, the secondary actuator will provide the required rotation of the thigh link and will continue to deliver the assistive torque. The article also effectively shows the application of BG approach to model the multidisciplinary systems like KE as it conveniently models the system containing various elements in different energy domains.

This paper deals with the modelling and obstacle avoidance of a biped robot. At first, the bond graph-based three-dimensional model of the biped is proposed. The robot walking scheme depends upon the oscillating cylinder mechanism. Two DC motors are actuating the prismatic leg of the robot. Then, bond graph model is converted into the Simulink block which is further used for obstacle avoidance application. The physical model of the biped robot is also fabricated. The second part of the work deals with the development of the hybrid obstacle avoidance algorithm by using the merits of the line following, tangent bug and wall following algorithm. The practicability of algorithm is validated on two cases depend upon the positions of the obstacle. The coding of the algorithm is developed by using MATLAB software. The single rectangular shape obstacle is considered for obstacle avoidance by the robot during experimentation work. At last, the validation of the simulation and experimentation work is considered.

The hybrid manipulators have benefits of both serial as well as parallel manipulators. In this paper, a planar hybrid manipulator with six degrees-of-freedom is proposed; it consists of two parallel manipulators each having three degrees-of-freedom. The models for forward and inverse dynamic analysis of this manipulator are presented with bond graph approach. The actuators of the manipulator have ball screw feed drive mechanism to convert rotary motion into linear motion. There are basically three problems addressed in the paper. First, the models are simulated for trajectory tracking of a semi-circular path traced by the lower manipulator initially and then tracking of another semi circular path by upper manipulators. The second problem addressed is to develop the bond graph model of the hybrid manipulator with proportional control to reach a desired position from an initial position with an unity slope after few seconds. Finally, workspace analysis for given semi-circular trajectory is done with calculation of area of the workspace of lower, upper and hybrid manipulators. It is observed from the simulation that the response follows the desired trajectory within the permissible limit. The result indicates that manipulator follows nearly tangential path. It is seen from the result that the desired trajectory lies within the workspace boundary.

With an increase in number of knee problems in patients., the demand for the rehabilitation has increased. Most of the rehabilitation trainings are expensive and time consuming. So., the need for personalized treatment in rehabilitation is increasing. The knee exoskeleton is one of such solutions to assist the patients suffering from weal knee., paraplegia and hemiplegia. These exoskeletons meet the patient’s expectation in terms of assistance required and wearing comfort. These are relatively more portable than lower body exoskeletons owing to their lighter weight. These can either be used for gait rehabilitation., providing assistance during sit to stand motion., normal walking and running., for load carrying augmentation or for performing activities of daily living. In this work., a knee exoskeleton consisting of a linear actuator and surface Electromyography sensor is designed and fabricated. Experiments are performed to validate the results with those of theoretical one. The developed knee exoskeleton is found to be well suited for assisting the wearer during the rehabilitation.

Industrial robots, generally, are composed of architecture with serial manipulators having large workspace but these suffer from several drawbacks, such as low accuracy and low load-carrying capacity. Similarly, the parallel architecture robots have better accuracy but small workspace. Therefore, the combination of serial and parallel chain architectures has become attractive as hybrid manipulators over the last two decades. A planar hybrid manipulator is proposed here and this is made by placing a planar parallel manipulator, having three degrees of freedom, each over the other in series so as to increase its load-carrying capacity and then it is modeled with the help of the bond graph approach. The human vertebrae are considered as a hybrid manipulator in this paper. The translation of the human vertebrae model on the frontal plane and lateral bending in the right- and left-hand directions are proposed here to increase the flexibility of the body part of humanoid robots used in industries and sports so that they can execute spine bending activities. The forward and inverse models for the manipulator are presented and the system inversion is carried out through the overwhelming controller. Finally, the simulation results for trajectory tracking of left-hand lateral bending in the frontal plane is done with or without the consideration of leg inertia and conclusions are presented to show that response follows the command within acceptable limits.

Keeping in view the role of heat generation and dissipation, the aim of this work is to develop a thermal model for the twin-tube hydraulic shock absorber using bond graph approach. In this paper, ...

Gas metal arc welding (GMAW) is extensively used for joining of different graded steels as well as aluminium and other nonferrous materials. GMAW offers clean welding with low defects without using flux and suitable for different positional welding. In the present work, a fabricated automatic movement setup is used for GMAW to study the influences of four different process parameters during joining of austenitic stainless steel AISI 316 using AISI 304 (ER304) filler wire. With this setup, welding is carried out maintaining a constant contact tube-to-workpiece (CTW) distance and uniform heat input. Experimental results and subsequent analysis show that the toughness is most significantly influenced by voltage followed by welding speed, gas flow rate, and current. Toughness reduces with the increase in shielding gas flow rate and welding speed as austenite and traces of retained delta ferrite may be present due to high solidification rate. Metallurgical observations by X-ray diffraction (XRD) and scanning electron microscopy indicate that solidification mode is mainly characterized by formation of fully austenite or austenite and ferrite at cell and dendritic boundaries. XRD results revealed that higher toughness is observed due to minimum formation of carbides.

In the present work, a simple arrangement is made to provide double layer shielding gas supply in addition to primary shielding during gas metal arc welding (GMAW) of two dissimilar stainless steels, i.e., AISI 316 and duplex 2205. Influences of double layer shielding in addition to five more process parameters like welding current, voltage, material of the electrode wire, the type of primary shielding gas, and flow rate on joint tensile strength and fusion zone microhardness are studied. An experimental design technique is used to design the experimental conditions and the results are analyzed to observe the influences of each process parameter and their interactions. The tensile strength is more influenced by the electrode material and the type of shielding, whereas current, interaction between current × voltage and current × flow rate significantly influence microhardness. Welding voltage influences both tensile strength and microhardness. Double layer shielding with CO2 as an outer shielding layer hel...

In the present paper three dimensional cutter deflections and the corresponding profile errors during end milling are predicted by finite element and bond graph modeling approach. The deflections have been modeled considering the cutter as a cantilever beam fixed at the collet end. Rayleigh beam model is used for modeling to consider the shear force effect, and Castigliano's theorem of strain energy is used to predict the deflections due to radial, tangential, and axial cutting forces. The tool-workpiece contact region is sliced into small elements to apply the forces on the entire contact region and predict deflections more accurately. The predicted deflections at different parametric settings are compared with experimental measurements by measuring the geometric accuracy of the cut profiles. The depth of cut has the most significant influence on profile deviations, while feed and speed have marginal effects. The results reveal that the predictions by finite elements and the bond graph closely matches wi...

In tungsten inert gas (TIG) welding, limited depth of penetration can be achieved during single pass welding. To achieve the desired depth of penetration, the speed of welding needs to be significantly reduced and hence, the productivity decreases. In the present work, the effect of TiO2 activated flux on penetration is evaluated for different workpieces namely AISI 1020, AISI 304, AISI 316, and Duplex 2205 steels at different currents and shielding gas compositions. The results show a significant increase in the depth of penetration and reduction in the width-to-penetration ratio using the activated flux for all the workpiece materials considered here. Current increases the depth of penetration, however, the influence of flux becomes more significant with higher welding current. Maximum of 37.8%, 44.3%, 47%, and 124% increase in depths of penetration is measured for AISI 1020, AISI 304, AISI 316, and Duplex 2205 steels, respectively, when activated flux is used. Also, maximum of 70% increase in the depth...

In the present work, the influence of heat input is studied on depth of penetration while depositing bead on AISI 304 stainless steel using an indigenously fabricated automatic gas metal arc welding (GMAW) movement setup. Depth of penetration and fusion zone profiles are predicted at different conditions by the bond graph modeling approach and validated using measured depth of penetration and fusion profile. The effects of heat input on toughness and metallurgical behavior are analyzed while joining AISI 304 plates using automatic GMAW. Heat input and gas flow rate significantly influence the toughness at room temperature and at −20°C. Metallurgical observations by scanning electron microscopy are carried out and it is observed that high heat input and lower cooling rate increase grain size. High heat input and rapid cooling prevent grain growth and lead to grain refinement.

Gas metal arc welding (GMAW) offers highly efficient and low-cost welding, but manual movement of torch affects the uniformity of bead geometry, penetration, and heat input. In the present work, an indigenous automatic movement setup is designed and fabricated for GMAW. System behaviors like drive motor response, carriage, and wheel movement are studied through bond graph modeling. Welding time and welding velocity obtained from simulation are used to obtain the deposition efficiency during weld bead deposition on low carbon steel and stainless steel workpieces. Spatter index is also calculated for both the materials. Welding performance of automatic welding is compared with manual movement welding, and automatic welding is found capable to offer high deposition efficiency, low spatter index, uniform depth of penetration, and lower distortion for both the materials. Variation in microhardness and metallurgical observations by scanning electron microscopy are carried out for microstructure analysis.

The road accidents due to traffic problems and human erroneous driving are the major challenges for researches. The self-driving car or mobile robot is the solution to avoid such mishaps. In this paper, an attempted has been made to develop obstacle avoidance algorithms for bicycle vehicle model of mobile robots. The hybrid obstacle avoidance algorithm is proposed on the merits of line, wall following and tangent bug algorithm. The trajectory generated from the hybrid obstacle avoidance algorithm is fed into the overwhelming controller of the bicycle vehicle model of mobile robot for avoiding obstacles. Then, the fuzzy logic (FL) based obstacle avoidance controller is proposed. Twenty-three set of rules are proposed for fuzzy logic approach. Both the obstacle avoidance algorithms are implemented on the bicycle vehicle model of the mobile robot. The dynamic model of the mobile robot is developed using bond graph theory and is converted into Simulink block using S-function directly from the library of SYMBOLS Shakti software. The vehicle model is equipped with three ultrasonic sensors to measure the distance from the obstacles. Three input membership functions and one output membership function are considered in fuzzy logic controller. During avoiding two static obstacles and reaching the target, the comparison of obstacle free paths traced by both obstacle avoidance algorithms is done in this paper.

This paper deals with the reconfiguration of an intelligent autonomous vehicle that utilizes an automatic navigation method and online supervision system and thus can be used to improve the safety, traffic management and space optimization inside the confined space of a port. The bond graph model of the vehicle’s dynamic system is developed in a modular and hierarchical modelling environment. An over-actuated intelligent autonomous vehicle with redundant actuators has four independent driven wheels, four independent braking wheels and a four-wheel steering system. This vehicle can be safely operated with appropriate control law restructuring even when some of its actuators are unusable due to a fault. For actuator fault detection, analytical redundancy relations, which are constraint relations that describe nominal system behaviour and are written in terms of the measured system variables, are derived from the bond graph model. Analytical redundancy relations are continuously evaluated to generate residual signals and the symptoms in these signals are monitored for actuator fault detection and isolation. Once one or more actuator faults are isolated, the system is reconfigured via the selection of an appropriate operating mode to prevent critical or accidental situations. This procedure is validated by considering a fault scenario with two reconfiguration options.

An overwhelming controller provides robustness against uncertain parameters, disturbances and un-modelled dynamics. A simplified inverse dynamics model is used in the present paper to develop an overwhelming controller for a parallel manipulator (a Stewart platform), where the controller accommodates modelling uncertainties such as the simplifications made for development of the inverse model in order to improve the computational efficiency. Such a control strategy leads to good trajectory tracking accuracy in the presence of unknown disturbances. However, in addition to trajectory tracking performance, the controller for a Stewart platform should also be able to control or limit the interaction forces in applications such as robot assisted surgery and low-impact docking. The environmental forces can be accommodated during the interaction period by modulating the impedance at the interface of manipulator and environment through virtual flexible foundations. The positional error induced during the force control phase can be recovered during the free flight or idle phase. While this approach has been used successfully in the past to control serial manipulators, the closed loop kinematic architecture in a parallel manipulator introduces many difficulties. This paper proposes a modified overwhelming control scheme for parallel manipulators with compensations for interaction force control and positional error recovery. Bond graph modelling is used as an integrated model and controller development tool. Force controlled machining on a spherical surface, which is akin to a surgical operation, is considered as an example application of the developed control strategy. The simulation results from the bond graph model of the controlled Stewart platform are presented to demonstrate the performance of the developed hybrid position force controller.

Neglecting dynamic load during design of a prismatic joint for high-speed operation may lead to unpredictable failures. A slider joint is usually a part of a pneumatic or hydraulic actuation device which may further involve complicated control systems. Thus, design/analysis of prismatic joints calls for a multi-energy domain modeling approach such as bond graph for reusability of the model in different application scenarios. The slider is treated to be a multibody system composed of two separate rigid bodies which are constrained to produce the desired motion. The constraints generate the dynamic contact forces which are used to compute the dynamic frictional forces. The bond graph model of the planar slider component developed in this article accurately calculates the dynamic loads. The model is first validated through numerical simulations performed on a Rapson slide. Thereafter, a multi-energy model for a V-twin engine and its mounting is developed to show how bond graph modeling makes it possible to create an integrated model of thermal, pneumatic and mechanical systems. Finally, the bond graph model of a three-dimensional prismatic joint is developed.

Antilock braking system (ABS), traction control system, etc. are used in modern automobiles for enhanced safety and reliability. Autonomous ABS system can take over the traction control of the vehicle either completely or partially. An antilock braking system using an on–off control strategy to maintain the wheel slip within a predefined range is studied here. The controller design needs integration with the vehicle dynamics model. A single wheel or a bicycle vehicle model considers only constant normal loading on the wheels. On the other hand, a four wheel vehicle model that accounts for dynamic normal loading on the wheels and generates correct lateral forces is suitable for reliable brake system design. This paper describes an integrated vehicle braking system dynamics and control modeling procedure for a four wheel vehicle. The vehicle system comprises several energy domains. The interdisciplinary modeling technique called bond graph is used to integrate models in different energy domains and control systems. The bond graph model of the integrated vehicle dynamic system is developed in a modular and hierarchical modeling environment and is simulated to evaluate the performance of the ABS system under various operating conditions.

Combined regenerative and antilock braking in electric/hybrid-electric vehicles provides higher safety in addition to an energy storing capability. Development of a control law for this type of braking system is a challenging task. The antilock braking system (ABS) uses a control strategy to maintain the wheel slip within a predefined range. A sliding mode controller (SMC) for ABS is developed to maintain the optimal slip value. The braking of the vehicle, performed by using both regenerative and antilock braking, is based on an algorithm that decides how to distribute the braking force between the regenerative braking and the antilock braking in emergency/panic braking situations as well as in normal city driving conditions. Detailed bond graph models of a quarter car and four-wheeled vehicles are used in this article to implement and test the control laws. It is found that with combined regenerative and antilock braking, the vehicle’s safety increases (in terms of stopping distance and manoeuvrability) and some amount of kinetic energy can be recovered and stored in the regenerative battery pack. The passenger comfort is improved when a sliding mode ABS controller is used in place of a standard ABS controller for the mechanical braking part. Moreover, the influence of load transfer on the wheels during braking was evaluated on a four-wheeled vehicle model.

An overwhelming controller-based implicit system inversion scheme is proposed in this work to control a hydraulically driven planar (three-degrees-of-freedom) parallel manipulator. The physical model-based design of the controller is developed by using bond graphs. The electro-hydraulic actuator in the leg is modelled by including the dynamics of the servo-valve and the cylinder. A leg-space force-feedback controller is proposed for controlling the hydraulic pressures acting on the pistons of the actuators. The objective is to develop a fast inverse model which is suitable for real-time implementation in the controller. It is shown that an approximate inverse model which correctly represents the kinematics of motion but has incorrect representation of inertias is sufficient for the controller design because of the high feedback gains used in the overwhelming control strategy. This controller, based on the approximate simple inverse model, generates the right driving forces for the actual system whose model is much more complicated and uncertain. Finally, the controller design for a planar vehicle simulator is considered as an example and the corresponding simulation results are used to validate the robustness of the model-based overwhelming controller to the modelling uncertainties.