Mitigating Collision Forces and Improving Response Performance in Human-Robot Interaction by Using Dual-Motor Actuators

In collaborative robotics, the safety of humans interacting with cobots is crucial. There is a need for collaborative robots that can move quickly while still being safe. This letter introduces the use of a kinematically redundant actuator in impedance control mode to reduce collision forces, aiming to improve both the safety and efficiency of collaborative robots. By distributing power across multiple drive-trains, each with unique properties such as reflected inertia, the actuator's behavior during collisions is optimized, which is key for safe interactions. Using theoretical analysis and practical experiments, we evaluate the response performance of the redundant actuator in various collision situations according to ISO/TS 15066, comparing it with that of a standard single-drive actuator. Our experiments show that the redundant actuator significantly lowers collision forces, with a 44% reduction in peak forces and an 81% decrease in transferred impulses during collisions. The letter concludes by offering a design parameter recommendation for designing actuators with reduced reflected inertia.