Adaptive robust control method for joint flexibility of collaborative robots based on uncertainty

Joint modules, as collaborative robot actuators, are typically modeled as motor-gear systems. Their significant flexibility arises from harmonic gear flexsplines, torque sensors, or extra elastic elements, making them rigid-flexible coupled motor-gear systems. Collaborative robots constitute a multivariable, strongly coupled, nonlinear, and time-varying uncertain system. This paper explores motor control, harmonic transmission dynamics, and joint flexibility/uncertainty. Dynamics modeling of single-joint robots is conducted, including rigid and flexible models. Applying Udwadia-Kalaba theory, servo-constraint adaptive robust control is designed based on approximate constraints, ensuring strict adherence. Simulations verify the controller's significant improvement in joint module dynamic performance.