Research On SCARA Robot Collision Detection And Impedance Control

With the wide application of robots,more and more tasks require cooperation between robots and humans.In the workspace of the robot,collisions would inevitably occur,causing harm to humans or robots.Therefore,the safety problem of human-robot interaction needs to be solved urgently and robot control strategies focusing on safety are becoming much more significant.This paper takes the 3-DOF SCARA robot as the research object,and analyzes its safety when performing the insertion task on the PCB.The main contents are as follows:Firstly,in order to obtain accurate dynamic parameters,the Lagrange method is used to establish the dynamic model of the SCARA robot,and the model parameters are identified.The parameter identification process includes model linearization,design and optimization of the excitation trajectory and usage of least squares to estimate the dynamics parameters.Furthermore,to obtain a complete dynamic model,the friction of the joint is modeled and identified,and the friction identification experiment is carried out on the SCARA robot platform.Then,on the basis of the dynamic model,the collision detection algorithm based on disturbance observer is analyzed.The disturbance observer based on generalized momentum is used to estimate the external torque without installing a torque sensor.This method eliminating the need to calculate acceleration,which effectively avoids system instability caused by acceleration information.In order to ensure the safety of human-robot interaction,this paper sets the collision detection threshold and takes three post-collision safety response strategies.The effectiveness of collision detection algorithm is verified through experiment and simulation.Finally,aiming at the problem of position and force control after 3-DOF SCARA robot collision detection,this paper takes a hybrid impedance control strategy to realize robot position tracking and force tracking during human-robot interaction.The hybrid impedance control strategy is proposed combining the position-based impedance control and the force-based impedance control.In the hybrid impedance controller,the force tracking control is performed in the constrained direction of the task space and position tracking control is performed in the direction of free motion.On the Simulink platform,taking disturbance observer to estimate external torque,simulation studies are conducted on the position tracking,constant force tracking,variable force tracking and the effects of different impedance parameters on the control system.