Mobility analysis of a typical multi-loop coupled mechanism based on screw theory and its drive layout optimization

Abstract

Improving the load-to-weight ratio of robots is an essential issue in the field of construction robots. In the present study, a method for analyzing the mobility of the typical multi-loop coupled mechanism is proposed, which combines the iterative replacement of generalized kinematic pairs with the screw theory. Then, the driving force/torque, driving power, and total power of actuators are considered as the evaluation indices, and the influence of different drive layouts on the mechanism is analyzed. Obtained results show that the driving force of the moving pair in the drive layout S1 or S3 changes smoothly compared with that in the drive layout S2, and the peak values of the driving force and the driving torque reduce by 49% and 12%, respectively. This demonstrates that the drive layout S1 effectively reduces the quality of the actuators. Finally, the coupled mechanism with the drive layout is applied in a high-altitude curtain wall installation robot, and the prototype of the robot is developed based on the coupled mechanism. Performed experiments show that the load-to-weight ratio in the proposed robot is about 13%.