Design and research of single degree of freedom planar multiple  joints mechanical arm

ZHAO Pengfei, HU Guoqing, SUN Qiwei, JIAO Liang

(School of Mechanical and Automotive Engineering, South China University of technology, Guangzhou 510641, China)

Abstract: Aiming at the automatic transmission requirement of sheet material in industry applications and the requirement of small space in vertical direction, a kind of single degree of freedom multiple joints mechanical arm was designed, which has low cost, large workspace and small occupied space. A kind of mechanical structure with 3 joints and 3 links was designed, the reducer and two synchronous belts for drive were used. Using the multiple coordinate system and the superposition principle of angular velocity, the kinematics of the endlink of the arm with arbitrary arm length and arbitrary transmission ratio of the belt was obtained, and the conditions of the linear movement of last link was obtained and verified by the experiment. The dynamical equation was obtained by Using Lagrange equation and it was verified by using ADAMS software, and the moment of inertia under any position was also obtained. A closed loop PID control system was set up, and under a trapezoidal path planning the driving torque in closedloop control system was simulated and researched. The results indicate that the conditions of the linear movement of the last link and the dynamical equation are correct, and the driving torque under the sample path planning may be greater than 25 Nm, and it provides a way and reference for the select of the driving component.

Key words: mechanical arm; multiple joints; transmission of sheet material; inverse problem of dynamics