Characteristic Analysis and Control Loop Design of Transmission Torque and Jerk for Flexible Joint Servo Systems

In collaborative robot joint servo systems, harmonic reducers are mostly adopted as transmission devices, which helps to achieve light weight and flexibility. However, the introduction of a harmonic reducer or other transmission devices inevitably introduces elasticity into the system, resulting in mechanical oscillations and decreased joint output accuracy, which will reduce the safety and accuracy of the transmission system. This article investigates the dynamic characteristics of the transmission torque and jerk, which play a key role in the performance of servo transmission. The traditional servo control structure is then replaced by a novel control loop structure consisting of position, transmission torque and jerk. The parameters of the loop controllers are designed by means of the pole configuration method and an evaluation function. Finally, the accuracy and transmission safety of the designed control structure are verified by both simulation and experiment.