An adaptive actor-critic algorithm is proposed under the assumption that a predictive model is available and only the measurement at time k is used to update the learning algorithms. Two value-functions are realized a...
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An adaptive actor-critic algorithm is proposed under the assumption that a predictive model is available and only the measurement at time k is used to update the learning algorithms. Two value-functions are realized as a pure static mapping, according to the fact that they can be reduced to nonlinear current estimators, which can be easily constructed by using any artificial neural networks (NNs) with sigmoidal function or radial basis function (RBF), if all the inputs to the present value-functions are based on simulated experiences generated from the predictive model. In addition, if a predictive model is assumed to be used to construct a model-based actor (MBA) in the framework of adaptive actor-critic approach, then this type of MBA can be viewed as a network whose connection weights are composed of the elements of feedback gain matrix, so that the temporal difference (TD) learning can also be naturally applied to update the weights of the actor. Since the present method can update the learning by using only one measurement at time k, a relatively fast learning is expected, compared with the previous approach that needs two measurements at times k and k + 1 to update the actor-critic networks. The effectiveness of the proposed approach is illustrated by simulating a trajectory-tracking control problem for a nonholonomic mobile robot.
We (2001) have proposed the "rings gymnastic robot" aiming at an application to the gymnastic coaching by understanding the ring exercises through the robot. The ring exercises have the characteristics that ...
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We (2001) have proposed the "rings gymnastic robot" aiming at an application to the gymnastic coaching by understanding the ring exercises through the robot. The ring exercises have the characteristics that the apparatus can move in all directions freely unlike the other gymnastic events. Fuzzy control is adopted as a control method for the rings gymnastic robot. As the joint torque in performance is useful for the coaching and gymnasts can easily understand the skill to realize performance if the control method is represented as "if-then" rules. In this paper, we derive a three-dimensional model of the robot and acquire the performance skill of a backward giant circle using the genetic algorithm. Three-dimensional graphics sequence based on simulation results shows that the obtained skill is effective.
Force-free control can realize the flexible motion of industrial articulated robot arms without any change of the built-in controller. In this paper, the force-free control was extended to realize the motion as if it ...
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Force-free control can realize the flexible motion of industrial articulated robot arms without any change of the built-in controller. In this paper, the force-free control was extended to realize the motion as if it were under the circumstance of any inertia, any friction and any gravity through the independent compensation of inertia, friction and gravity. The property of the force-free control with independent compensation was also investigated by the experimental study of an actual industrial articulated robot arm, where the external force was measured by the force sensor which was attached to the tip of the robot arm.
This paper presents a general methodology for designing controller for block-oriented industrial nonlinear system by nonlinear separation control with neural learning. In this study, through rough approximation of inv...
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ISBN:
(纸本)0780376315
This paper presents a general methodology for designing controller for block-oriented industrial nonlinear system by nonlinear separation control with neural learning. In this study, through rough approximation of inverse input output nonlinear statics and accurate compensation of nonlinear dynamics with rigid definition of neural network as well as learning from actual system, control performances can be improved. Based on this method, high-precision contour control of industrial articulated robot arm and outlet working fluid heat rate control of evaporator in energy conversion plant were realized. The experiment and simulation verified the significant potential of the proposed method to industrial nonlinear systems.
We propose a method of fuzzy rule extraction for switching partly stable controllers (PSCs) for online operations of underactuated manipulators. The fuzzy rule base of switching the PSCs is optimized using GA and the ...
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We propose a method of fuzzy rule extraction for switching partly stable controllers (PSCs) for online operations of underactuated manipulators. The fuzzy rule base of switching the PSCs is optimized using GA and the optimization is performed off-line. Design parameters of the fuzzy rules are encoded into chromosomes and shapes of the Gaussian functions are evolved to minimize the angular position errors. The angular position errors are used as the inputs to the Gaussian membership functions in the antecedent part and the one index of the PSCs is assigned in the consequent part of the fuzzy reasoning. Then, this trained rule base can be brought into the online operation of the underactuated manipulator. The effectiveness of the concept is illustrated by taking a 2-DOF RR planar manipulator and results show the effectiveness of the proposed control methodology.
Addresses the trajectory tracking problem of industrial robot manipulators, at the corners of a Cartesian three-dimensional trajectory. The goal is to determine the maximum tangential velocity of the end-effector as i...
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ISBN:
(纸本)0780376315
Addresses the trajectory tracking problem of industrial robot manipulators, at the corners of a Cartesian three-dimensional trajectory. The goal is to determine the maximum tangential velocity of the end-effector as it traverses a circular arc at a trajectory corner while avoiding joint acceleration saturation. The proposed method first derives the relationship between end-effector velocity and joint accelerations, and then develops a criterion to determine maximum tangential velocity so that only one joint marginally reaches its acceleration limit at a single point on the circular arc. The method was successfully experimented with, and improved performance has been demonstrated.
Nonlinear separation control method was constructed for a STEC (spring thermal energy conversion) pilot plant. The nonlinear separation control consists of nonlinear statics compensation and linear dynamics compensati...
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ISBN:
(纸本)0780373227
Nonlinear separation control method was constructed for a STEC (spring thermal energy conversion) pilot plant. The nonlinear separation control consists of nonlinear statics compensation and linear dynamics compensation. In this paper, evaporator outlet heat quantity of working fluid was controlled by use of the nonlinear separation method.
Skillful motor control of human is achieved by the appropriate motor commands generating from the central nerve system. Internal model in the cerebellum may have great contribution for realizing accurate motor control...
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The adjustment of servo parameters of industrial mechatronic servo systems is generally approached according to a certain empirical rule, but it is difficult to achieve a high performance. This paper describes the con...
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ISBN:
(纸本)4907764197
The adjustment of servo parameters of industrial mechatronic servo systems is generally approached according to a certain empirical rule, but it is difficult to achieve a high performance. This paper describes the contour control by the modified input data method for industrial mechatronic servo systems so that the adjustment of servo parameters is not required. Under a given set of servo parameters within an allowable range, the effectiveness of the proposed method has been verified by the simulation and experimental study on contour control of an experimental mechatronic servo system.
It is important for walking robots such as quadruped robots to have an efficient gait. Since animals and insects are the basic models for most walking robots, their walking patterns are good examples. In this study, t...
It is important for walking robots such as quadruped robots to have an efficient gait. Since animals and insects are the basic models for most walking robots, their walking patterns are good examples. In this study, the walking energy consumption of a quadruped robot is analyzed and compared with natural animal gaits. Genetic algorithms have been applied to obtain the energy-optimal gait when the quadruped robot is walking with a set velocity. In this method, an individual in a population represents the walking pattern of the quadruped robot. The gait (individual) which consumes the least energy is considered to be the best gait (individual) in this study. The energy-optimal gait is analyzed at several walking velocities, since the amount of walking energy consumption changes if the walking velocity of the robot is changed. The results of this study can be used to decide what type of gait should be generated for a quadruped robot as its walking velocity changes.
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