Structural Design and Position Tracking of the Reconfigurable SCARA Robot by the Pre-Filter AFE PID Controller

Abstract

The selective compliance assembly robot arm (SCARA) has been developed for decades and has been widely used in industry due to its light structure, quick response and high stiffness in a specific axis. In this work, we designed a reconfigurable SCARA robot with extensible physical space by adjusting the number of modular arms. Considering potential structural failure due to vibration, we employed a multi-objective optimization method based on the finite element method to optimize the bolt connectors between the modules. Compared with the classic finite element optimization method, this method focuses on the key factors affecting the precision of the reconfigurable robot; we used the fitting method of the multi-objective function to obtain the influential factors, which make the optimization results more consistent with a real situation. Then, exploiting the acceleration feedback enhanced (AFE) control strategy, a pre-filter AFE PID controller is proposed by introducing a pre-filter to effectively suppress the system disturbance, which is caused by gaps between the joints when the robot operates at high speed. Experiments show that the reconfigurable SCARA robot still has strong stability under the continuous disturbance of a 2 kg hanging plate weight.