Impact and force control

Robot manipulators and drive systems can experience instability or poor control performance after impacting with an environment. The authors present an analytical model for impact which is experimentally validated step-by-step. Extensive simulations and experiments are conducted to explain impact phenomena for the case of a force feedback control of a single-axis drive system. The experimental tests were conducted on a manipulator drive system which consists of a motor, a transmission, a link, a force sensor, and a movable environment. The results are based on an energy method and presented concisely in dimensionless form. To this end, a small number of dimensionless groups are used to characterize the impact behavior through simulations and tests. It is shown that integral force compensation with velocity feedback improves force tracking and reject impacts. It is also revealed that impact response can be tuned by selecting a favourable dimensionless ratio of force to approach velocity