Research On Robot Screwing Valve Based On Hybrid Active/Passive Compliance

With the rapid development of nuclear power technology,nuclear power plant rescue operations are receiving more and more attention all over the world.Valve screwing,which is one of the basic tasks in nuclear power plant,has also gradually attracted widespread attention.To protect the safety of relief workers,one of the best ways is to use robots to perform the operation.Considering the actual problems of robot screwing valve,this paper proposes a new strategy,which integrates compliant mechanism and adaptive impedance control,and makes comparatively deep analysis about the strategy.Firstly,causes of errors for robot teleoperation have been analyzed and classified.The analytical models of different types of errors and forces/torques of robot end have been established.This paper builds the forward kinematics model and Jacobian matrix of six DOFs robot,and establishes the mapping function of forces/torques of robot end and robot joint torques.The simulation model of robot screwing operation is established,and the simulation analysis results have proved the validity of above calculation.Secondly,considering the main problems of robot screwing valve,this paper adopts passive compliant mechanism to handle the lateral forces/torques,and adopts adaptive impedance control to realize the tracking of valves handle's axial position.A Hooke hinge mechanism based passive compliant end effector is designed,and its compliance ability is accomplished.The trajectory planning of robot screwing valve is designed.The simulation platform of screwing valve is built in ADAMS,and the simulation experiments are completed,the simulation results have demonstrated the effectiveness of the passive compliant end effector.And also the experimental platform for robot screwing valve is established,the relevant screwing valve experiments are executed by using the end effector.Finally,aiming at the handle's axial displacement in the process of screwing valve,this paper adopts position based impedance control to track the handle's position.The steady-state force tracking error of impedance control is analyzed,and the simulation analysis of the performance of impedance control system is carried out.Considering the shortage of impedance control,this paper further adopts adaptive impedance control,designs the adaptive control law based on Lyapunov stability theory,builds adaptive impedance control system,and accomplishes the analysis of the performance of adaptive impedance control system.The relative simulation of screwing valve is accomplished based on MATLAB/ADAMS joint simulation platform.And then,the robot screwing valve experiments based on integrated active and passive compliance are accomplished by using the designed experiment platform.