The introduction of intrinsic compliance in the design of robots allows to reduce the risk for humans working in the vicinity of a robotic cell. Indeed, it permits to decouple the dynamic effects of the links’ inertia from those of the rotors’ inertia, thus reducing the maximum impact force in case of a collision. However, robot designers are lacking modeling tools to help simulate numerous collision scenarios, analyze the behavior of a compliant robot, and optimize its design. In this article, we introduce a method to reduce the dynamic model of a multi-link compliant robot to a simple translational mass-spring-mass system. Simulation results show that this reduced model allows to accurately predict the maximal impact force in case of a collision with a constrained human body part. Multiple impact scenarios are conducted on two case studies, a planar serial elastic robot and the R-Min robot, an underactuated parallel planar robot, designed for collaboration.
Journal of Mechanisms and Robotics Open Issues