Research On Adaptive Impedance Control Simulation Of Haptic Device

A haptic device is a man-machine interaction device that can supply force feedback and greatly enhance immersion for user interacting with virtual environment.When the people operate on the haptic device,the force exerted by the operator on the haptic device can be measured by the force measuring device.To control the force between the operator and the haptic device,a method of impedance control is required.we need to use the impedance control method to control the haptic device.Thus,the paper develop the adaptive impedance control method for simulation based on haptic device.First,the haptic device that is original designed in our laboratory,is demonstrated its mechanical component,actuators,sensor and data acquisition.Specially,we elaborate the selection type for the actuators,and the data acquisition for the joint sensor in haptic device.In addition,we also give the analysis in the principle and performance for the haptic device.Second,the kinematics and dynamics analysis of the haptic device is carried out.The kinematics equation of the haptic device is established,the working space and the Jacobian matrix is obtained by kinematics analysis.Simulation for the kinematics of haptic device was carried out by using Matlab robot toolbox to verify the correctness of the kinematics model.The Lagrangian method is applied to analyze the dynamics and the kinetics equation is structured for the subsequent design in adaptive impedance control.Third,we study the adaptive control simulation of haptic device.Using the Simmechanics tool based on Matlab,creating the simulating model for the haptic device.The adaptive impedance control system is implemented based on Simulink environment with its parameters being achieved in simulation.Furthermore,the tracking curve of displacement and contact force can be also obtained by this simulation.The result shows that the adaptive impedance control method has the advantage of not requiring precise dynamic model,which can enable the end effector of haptic device to accurately maintain the desired contact force.This also further demonstrate that the adaptive impedance controller has preferable robustness to deal with the change of the external environment.Fourth,a fuzzy self-turning method is also utilized to find the optimal value of impedance control parameters.In order to facilitate the determination of the impedance control parameters,the fuzzy self-turning method is used to online optimize the impedance control parameters.The results shows that the optimal value of the control parameters can be achieved by detecting the change rate of the position with making fuzzy rules and fuzzy reasoning during the simulation process,which save time for determining control parameters and improve the control effect.Finally,we also use the traditional particle swarm algorithm to optimize the control parameters that are regarded as the position of the particles.The optimal particle position is obtained by iteratively computing with the fitness function.The results show that the optimal impedance control parameters optimized by off-line particle swarm algorithm optimization render a good control effect.