A Multiple Working Mode Approach to Hammering with a Modular Reconfigurable Robot

摘要

Robot joints could be damaged by impulsive forces due to impact when the robot performs hammering operations. This paper presents a strategy that allows a modular and reconfigurable robot to safely perform nail hammering in 3D space without hardware enhancements. To do this, a multiple working mode approach is applied to switch the selected joint(s) to passive mode with friction compensation to allow free rotation during impact. Analytic impulse models are used to predict joint impulses which can be computed offline or online and serve as criteria for mode switching. End-effector pose, and link momentum are proposed as criteria to track and time the switching. The strategy assumes multiple swings are performed with the last swing resulting in a collision with the board or wall. Joint impulses are constrained in case the hammer collides with such an object of infinite effective mass. Advantages of the proposed approach may include savings on space, weight, costs, and complexity for a limited range of nail/board environments. An experimental study validates analytic models of hammering and effectiveness of multiple working mode approach.