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Some of the important mechanical loads in the civil and military industries are variable speed and power and their efficiency. Mechanical coupling of two different electric motors is suitable for These types of application. Using this technique reduces energy consumption of submarine’s motion system and submarine range would be increased. But the use of this technique requires a complex controller. Setting the desired speed for the mechanical load-axis and sharing power on two motors are the main objectives of control. Previously controllers divided load power between two motors as non-optimal controller. This article presents a new controller that can perform the above objectives and is divided between two motors as optimal controller for all speeds. The method of this article will increase efficiency for all speeds, increase the range of submarine and reduce energy consumption for Paper industry and other similar cases. Simulation results have identified new control benefits than the previous model and tested a sample of 13% increase in efficiency.

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In this paper a continuous-time state-space aerodynamic model has been developed based on the boundary element method. First, boundary integral equations for unsteady potential subsonic flow around lifting bodies are presented with emphasis on a modified formulation for thin wings. Next, the BEM discretized problem of unsteady flow around an arbitrary wing is recast in the form of a state-space model using some auxiliary assumptions. To validate the proposed model, its predictions for unsteady aerodynamic coefficients due to various unsteady flows about different wing geometries were compared to the verified results of the direct boundary element solution and good agreement was observed. Because of the resulting aerodynamic model has been constructed in the continuous-time domain, it is particularly useful for optimization and nonlinear analysis purposes. Moreover, its state-space representation is the appropriate form for an aerodynamic model in control applications.

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This paper aims at obtaining the dynamic models of twoconstraint-over parallel mechanisms (PM) with 3-DOF (degree of freedom) and 4-DOF, the Tripteron and the Quadrupteron. The reasoning used in this paper is based on a judicious concept in detaching the whole mechanism into several subsystems and consecutive synergies between kinematic analysis, Lagrangian and Newtonian approaches. In this regard, the mechanisms are made equivalent to some subsystems and the equations of kinematic constraints are derived for all subsystems. Afterwards upon resorting to Lagrangian approach and blending it with the latter kinematic relations, the dynamic model of each leg in task space is obtained. The dynamic model of the end- effector is written in virtue of Newton-Euler’s approach where yields to three differential equations. Finally, the problem leads to a system of 12 equations for the Tripteron and 16 equations for the Quadrupteron, which do not need usaul simplifications in such problems. For the sake of comparison, the results are put into contrast by the one obtained with a dynamic analyzer software. The results obtained by both approaches are coherent which affirms the correctness of the proposed algorithm.

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In recent years many investigations have been performed on design and fabrication of micro mechanical manipulators. These manipulators have a wide application in industry specifically medical applications. A practical usage of this manipulator is endoscopy system. In the endoscopy system, we need a small manipulator with high maneuverability and flexible body to make the probe’s movement into a colon easier than classic manipulators. In this paper a basic flexible module is developed for use in this structure. Connecting three wires of shape memory alloy uniformly distributed in circumference of a compressive spring with angle of 120 degrees, it is possible to make an almost large displacement in the end planes with small strain of wires. In this paper, a model is developed to define the spring deformation which in the following is coupled with the model of SMA wire presented by Brinson to describe the module behavior definitely. Dynamic modeling and simulation is implemented in MATLAB-Simulink and module performance in addition to proper geometry for the considered application is extracted. Through the results of simulation verified by experiment, proper parameters of module for providing more deflection and rotation when activated by SMA are extracted.

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In this paper, dynamic behavior of a nano particle on a rough surface in pushing based on the atomic force microscopy (AFM) was modeled and simulated by using the multipoint contact model. First, a multipoint contact model was extracted for two different roughness profiles of rough surfaces including the hexagonal and tetrahedral by combination of the Rumpf singular point contact model with JKR and Schwarz contact models, and the equations of the real contact area and adhesion force were proposed for multipoint contact of rough surfaces. Then, the dynamic behavior of particles in pushing on the rough substrate was modeled by using the new multipoint contact model. Additionally, simulation of the particles dynamics with radii of 50, 400 and 500 nm in moving on the different rough substrates was performed and analyzed, by assuming multipoint, singular point contacts, and flat surface contacts. Results showed that the multipoint contact model, especially in small radiuses of roughness has an essential impact on determining of the critical force. Moreover, assumptions of the flatness or the singular point contact leads to a considerable error to estimate the critical force. Results showed profiles of rough surface and roughness distribution are very important factors in determination the numbers of the contact points, and change the estimated amount of the critical force. In general, the obtained critical force based on the new multi‌point contact model in comparison with the ones based on the flat surface and the singular point contact models, was decreased and increased, respectively.

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In this paper, constraint equations are derived based on the kinematic model of the robot and Lagrange method is applied to derive the dynamic equations. In order to control the robot position on planned reference trajectories, in presence of uncertainties of the dynamic model, an adaptive robust controller with uncertainty estimator is designed which is robust against the uncertainties and induced noises. The proposed controller consists of an approximately known inverse dynamics model output as model-based part of the controller, an estimated uncertainty term to compensate for the un-modeled dynamics, external disturbances, and time-varying parameters, and also a decentralized PID controller as a feedback part to enhance closed-loop stability and account for the estimation error of uncertainties. Performance of the designed controller is simulated and evaluated in different conditions including the presence of noise and parameters variation. In this regard, a comparison has been made between the response of the proposed adaptive robust controller and response of a feedback linearization controller, indicating their capabilities in noise rejection and compensation of parameters variation. Also, the results show that the proposed sliding mode controller has a desirable performance in tracking the reference trajectories in presence of the model uncertainties and noises for this kind of parallel mechanism.

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In this paper, dynamic modeling and control of a three-degrees-of-freedom parallel robot with pure translational motion is performed. Constraint equations are derived based on the kinematic model of the robot and Lagrange method is applied to derive the dynamic equations. In order to control the robot position on planned reference trajectories, in presence of uncertainties of the dynamic model, a sliding mode controller is designed which is robust against the uncertainties and induced noises. Performance of the designed controller is simulated and evaluated in different conditions including the presence of noise and parameters variation. In this regard, a comparison has been made between the response of the proposed sliding mode controller and response of a feedback linearization controller, indicating their capabilities in noise rejection and compensation of parameters variation. Also, the effect of defining different sliding surfaces on the performance of the sliding mode controller, and using the integral of error instead of the error itself, have been studied and examined. Results show that the proposed sliding mode controller has a desirable performance in tracking the reference trajectories in presence of the model uncertainties and noise for this kind of parallel mechanism.

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In this paper, design of an adaptive controller, as a combination of feedback linearization technique and Lyapunov stability theory, is presented for a parallel robot. Considering a three degree-of-freedom parallel mechanism of the robot, which serves pure translational motion for its end-effector, kinematic and constraint equations are derived. Then the dynamic model of the constrained system is extracted via Lagrange’s method to be used in the robot control. Two optimized trajectories are designed for the end-effector in the presence of some obstacles using harmony search algorithm to be tracked by the robot. An objective function is defined based on achieving to the shortest path and also avoiding collisions to the obstacles keeping a marginal distance from each. The first trajectory is a 2D path with four circular obstacles and the second is a 3D path with three spherical obstacles. Performance of the designed controller is simulated and studied in conditions including external disturbances and varying system parameters. The results show that the proposed adaptive controller has a suitable performance in control of the end-effector to track the designed trajectories in spite of external disturbances and also uncertainty and variation of the model parameters.

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In this paper, dynamic modeling and position control of a nonlinear servo – hydraulic actuator system under variable loads is proposed. In dynamic model of the under studied system, governing equation of valve, leakage and friction is considered. To achieve to the desired performance of the system under variable loads with extend variation amplitude, a one control method is applied which is robust in the presence of the variation. Also, as a nonlinear servo hydraulic actuator system has a nonlinear dynamics and the extracted dynamic model is not accurate to proposed behavior of the system, one controller can be required which is robust against the nonlinearity and uncertainty effects. The controller should be having an appropriate response, more accuracy and stability. Regarding to position control of the nonlinear servo hydraulic actuator system in presence of variable loads, nonlinear controllers are designed using feedback linearization and sliding mode techniques. In addition, in order to show the robustness of proposed controllers, a time varying disturbance and noise are applied in the simulation and results of the simulation are compared with classical PID controller. Controller parameters is optimized using harmony search algorithm and simulation results show the outperforming of sliding mode control in spite of variable loads against feedback linearization technique and PID controllers.

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Currently, hovering type autonomous underwater vehicles (HAUV’s) are very noteworthy, due to theirs unique capabilities and features. Appropriate maneuverability and controllability is the most important feature for a HAUV that, make it better than other AUV’s. In order to increase stability and controllability of robot, the ballast tank is applied for a HAUV. Using of ballast tank in HAUV was not common before. In this paper a new underwater vehicle is presented, including three ballast tanks and three thrusters. In this underwater vehicle, the number of thrusters is less than original robot. In this paper, dynamics modeling and tracking control of this new underwater vehicle is investigated. The results show that the heave and pitch DOF’s can be reachable by using of the ballast tanks and we don’t need to use extra thrusters for these degrees of freedoms.

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According to numerous capabilities and increasingly military and commercial applications of radio controlled helicopters, many investigations are being performed on these unmanned aircraft vehicles. Due to nonlinear, complex, unstable and coupled dynamic system and also existing limitations on manual control, the ability of automatic control of these vehicles has gained great importance. In this paper, in addition to investigating different methods of unmanned helicopters dynamic modeling, a multi-level simulator environment has been designed and implemented for flight performance analysis and effects of different parameters have been investigated. The main importance and innovation of present simulator is in possibility of dynamic flight simulation of helicopter using different theories for applications like control system design, performance analysis and real flight simulation. The main difference of the utilized methods is in theories and assumptions applied in main rotor and its flapping dynamics modeling. For each level, Kalman filter and control system design have been performed and preliminary results show the acceptable performance of estimator and controller systems. Considering the complexity of real unmanned helicopter behavior compared to previously performed models, the proposed multi-level simulator can be used as an appropriate tool for the first step before real flight tests.

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To get the real answer a PEM fuel cell system to load changing, dynamic modeling is necessary because static modeling independent of time and it shows the system performance in just one or a few points. In this study, the dynamic performance of a PEM fuel cell stack is modeled in the Matlab Simulink and is validated by the data available in the literature. Modeling is done in two parts; in the first part, the input gases to the fuel cell stack are dray and the second part, the gases entering to the stack are humidification. In order to investigate dynamic response of system to rapid changes in electrical current, the variable electrical current is entered into the system step by step then the effect of this change on output voltage, consumption of reactants, temperature and pressure are obtained. Analyzing results of first part indicates that the time delay of system response to electrical current changes. With increasing the electrical current, the temperature of cell body, consumption of reactants and amount of input gases into the anode and the cathode channels are increased. The temperature of anode and cathode channels and fuel cell body are different and with increasing the stack power are more differences. Analyzing the results of second part indicates that with increasing the relative humidity of input gases the ohmic loss and so on the body temperature of fuel cell is decreased.

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In this paper, an optimal adaptive sliding mode controller of an Omni-Directional Mobile Robot (ODMR) is proposed using harmony search algorithm. First, kinematic model of the robot is derived and then, governing equations of dynamic model have been obtained using linear and angular momentum equilibrium. Since the derived model is not an exact definition of the system, it includes some uncertainties. To compensate them, a tracking control method has been offered. The proposed controller consists of an approximately known inverse dynamic model output as the model-based part of the controller, an estimated uncertainty term to compensate for the un-modeled dynamics, external disturbances, and time-varying parameters to enhance closed-loop stability and account for the estimation error of the uncertainties. In order to compare the results of the proposed controller, an optimal feedback linearization and sliding mode controllers are designed and then, a cost function has been defined by combining the variation rate of control signal and the integral error index. This cost function has been minimized using harmony search algorithm, resulting in optimum control parameters. Finally, the performance of the designed controller in different conditions, such as in presence of disturbance and system parameter variation has been simulated and discussed.

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In this paper, an optimal robust hybrid active force controller based on Harmony Search Algorithm is designed for a lower limb exoskeleton robot. Dynamic equations are derived using Lagrange method by considering three actuators on the hip, knee and ankle joints to track a specific trajectory. One of the major problems of exoskeleton robots is non-synchronization of movements and transfer of power between the robot and human body which affects the robot in form of disturbance. In order to mitigate the effect of disturbances and increase precision, combination of active force control (Corrective loop of control input) with position control is used as an effective and robust method. In the active force control, to elicit robust input control against disturbances, the moment of inertia of the links is estimated at each instant by minimizing the Criteria of ITAE and the control input rate, using the Harmony Search algorithm and the control input is modified. Also, two controllers are designed for the position control loop using sliding mode and feedback linearization methods. In order to validate the performance of the designed controllers, the robot is modeled in ADAMS and control inputs are applied to the Adams model. For appropriate comparison, all control parameters are optimized using the harmony search algorithm and then performance of position controllers are compared in hybrid and conventional (without the force control loop). Results indicate the outperforming of the hybrid sliding mode controller rather than to the other designed controllers.

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This paper focuses on the dynamic modeling of quadrotor with respect to changes in operating conditions. The main objective of this investigation is to provide complete governing quadrotor dynamic equations using the Euler-Lagrange method considering all aerodynamic forces which affect it's motion. In previous papers, dynamical equations are never considered comprehensively. The study of quadrotor's dynamics permits to understand it's physics and behavior and provides a precise model of the system. Once such a model is obtained, the control of quadrotor turns much simpler than current inaccurate models. In order to take into account, the set of forces and torques involved in quadrotor dynamics, the previous studies are used and after describing each of the forces and their precise terms, the complete dynamic quadrature model is presented. At the end, the system's performance is simulated in two different operating conditions, one regardless of the external object coupled with quadrotor, and the other in the coupled condition with a camera, and by this means, the achieved dynamic model is validated. In the first operating conditions in two different tests, the dynamic equations of the present work will be compared against the previous ones. In the second operating conditions, the quadrotor performance under influence of a connected camera whose motion changes continuously the system dynamic equations is studied.

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In this paper, an optimal robust nonlinear model predictive controller based on harmony search algorithm is designed for a type of 3-DOF translational parallel robot. Dynamic model of the mechanism is derived using Lagrange method and the model predictive controller augmented by uncertainty estimator is designed and stability is proved by Lyapanov theorem. Performance of the designed controller is evaluated in different conditions such as presence of disturbance and parameter variation. Furthermore, an optimal trajectory consisting four circular obstacles is designed as the reference trajectory of the robot. In order to obtain the optimum control parameters, a cost function combining control signal rate and error is considered and minimized by harmony search algorithm. In order to compare the performance of the designed controller with other nonlinear controllers, two controllers, an optimal sliding mode and a feedback linearization controller are also designed and their results are compared. Simulation results depict the desirable performance of the three controllers in spite of disturbance and model uncertainty, however, error criteria indicate priority of the robust nonlinear model predictive controller over the two other controllers.

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In this study, a dynamic based control algorithm for a six-link quadruped locomotion is proposed. Up to now, a lot of robotic scientists have researched in quadruped locomotion but most of their researches are based on modeling of robot and its surrounding. Such methods are not able to generate a stable locomotion when the surrounding changes a little. So this is important to propose a dynamic based control algorithm. The algorithms that can guarantee the stability are classified to two categories of dynamic based and trajectory based methods. The trajectory based algorithms need detailed information of gait and surrounding which is not necessarily available. But the dynamic based algorithms use some geometric constraints to reach a stable controller. These geometric constraints generate the proper gaits. So in this study by employing the dynamic based control algorithm, we proposed a controller for generating the Trot and Pace gait on a straight and flat path for quadruped robot locomotion. Given that the quadruped robot has four degrees of freedom so three geometric constraints are needed to provide a rhythmic locomotion. In this study we showed that for step generating by quadruped robot, both the appropriate initial conditions for angular velocities and presence of a point mass on the neck of the robot are needed. Also in this study the stability of quadruped locomotion has been proved using Poincaré return map.