Research On Robot ARM Collision Detection And Response Strategies And Compliance Control Algorithms

Collaborative manipulators have gradually become a research hotspot.The research of human-machine collaboration is developing towards dealing with the complex operating environment,which puts high requirements on the safety of manipulators.In order to perform human-machine collaboration on the premise of safety,the manipulator must have the ability to perceive and respond to external physical collisions,and have the ability to identify external forces accuratelyat the same time.Most of the current researches that realized these fuctiongs are based on force sensors for the detection of external forces,and most of the lightweight collaborativemanipulators on the market are equipped with high-performance torque sensors,which makes the cost of these arms greatly increase.The manufacturing cost of the collaborative manipulators can be significantly reduced if sensorless external collision detection and external force sensing functions are implemented.The representative sensorless collision detection algorithm is a collision detection algorithm based on observing generalized momentum disturbance.This algorithm can track external disturbance torque quickly and accurately.The algorithm is simulated and analyzed in this paper,and an observation algorithm that takes into account the motor inertia and frictional damping is constructed.The function of estimating the external disturbance torque is realized by using the motor current command.A sensorless arm collision detection and reaction function is implemented.For the human-machine collaboration function of the manipulator,this paper uses the idea of mapping the estimated external disturbance torque to the joint space trajectory command.An inertia adjustable compliant control algorithm is constructed by mapping the disturbance torque estimate to the joint acceleration command.The algorithm presents inertial characteristics in the human-machine collaboration process and is able to change the inertiaby adjusting the parameters properly.This paper also constructs a compliant control algorithm with adjustable impedance by mapping the disturbance torque estimation value to the joint velocity command.During the human-machine cooperation process,the compliance control algorithm presents the impedance characteristic,which can be adjustedby changing the algorithm parameters.The advantage of the compliant control algorithm designed by using this idea is that there is no need to change the servo control algorithm of the manipulator,and the human-machine collaboration function of the manipulator is implemented at the trajectory planning layer.To verify the effectiveness of the proposed algorithm,a two-degree-of-freedom robotic arm experimental platform was designed.On the platform,the joint torque measured by the torque sensor and the motor side torque obtained by the motor current command was used as the algorithm input.And realized the collision detection algorithm based on the generalized momentum disturbance observer.Andthe collision detection and response strategy experiments are conducted based on these two methods.The inertia adjustable compliance control algorithm and the impedance adjustable compliance control algorithm aretestified.Sensorless manilupator collision detection and response and compliance control are achieved based on current commands.And the performance of achieving the above algrithmusing the current command are compared to the performance by using torque sensor.and the deficiencies and room for improvement are presented.