Modeling and control of inherently safe robots with variable stiffness links

摘要

In this paper, the modeling, control design, and trajectory planning for inherently safe robots with variable stiffness links (VSL) are investigated. Firstly, a dynamic model of VSL robots is developed using the pseudo-rigid-body model (PRBM). Based on PRBM, a feedback-linearization based controller is proposed. Extended state observer and deflection feedback are designed to improve the robustness and vibration suppression. To keep the inherent safety, a safe trajectory planning problem is formulated and the safety criterion is converted to a velocity constraint. With constraints on the jerk, acceleration, and velocity, the trajectory-planning problem is formulated as a time-optimal problem. The analytical solution of this problem is derived by optimal control theory. Experiments show the performances of motion control and vibration suppression of the proposed controller. The impact test results indicate the potential of VSL robots for applications with physical human robot interaction. (C) 2019 Elsevier B.V. All rights reserved.