This paper presents a cushion control method to reduce the impact force when the pressure foot presses onto the workpiece in the robotic drilling process. The design of a slide mode controller, which is based on a non-linear model of the pneumatic servo system of the pressure foot and a friction compensation model, is presented. A closed-loop motion control system of the pressure foot is implemented, in which the relative position between the pressure foot and the workpiece is used as the command and the movement between the pressure foot and the feed axis of the end-effector is used as the feedback signal. By employing the developed motion control system, fast positioning of the pressure foot onto the workpiece can be achieved with low impact force. According to the experimental results, when controlled with the proposed controller, the impact force of the pressure foot onto the workpiece can be reduced to 2.5% of that without position servo cushion control.
FANG Qiang, ZHOU Qing-hui, FEI Shao-hua, MENG Xiang-lei, BA Xiao-fu, ZHANG Yan-ni, KE Ying-lin. Pneumatic servo control system design for pressure foot of an end-effector. JOURNAL OF ZHEJIANG UNIVERSITY (ENGINEERING SCIENCE), 2014, 48(8): 1442-1450.
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