The Design Of Series-Parallel 7-DOF Humanoid Arm

The humanoid robot is one of the most active domains in the study of robots, and the arm is the vital component of the robot. This paper analyzes a new type of humanoid arm with series-parallel mechanism. The existence of the spherical 3-DOF(Degree-Of-Freedom) parallel mechanism makes the positional solution for the humanoid arm more complex, but the introduction of the new inverse solution to position for the orthogonal spherical 3-DOF(Degree-Of-Freedom) parallel mechanism accelerates the speed of computing, so an efficient positional equation is formed. The relationship between the parameter of parallel manipulator and workspace is studied with the intervene equation that developed for the shoulder and wrist joints. Based on this analysis and the demand of technics for manufacture and assemble the design of humanoid arm and its reachable workspace are provided. During the formulating of the velocity equation of the arm a method is offered to establish the Jacobian matrix of velocity of the parallel joint. Kinematics isotropic index of the arm is plotted out. The force equations of the arm and the joints are formated. As an example the bearing capacity of the shoulder joint is analyzed in its complete workspace, and the workspace for the rated load workspace is plotted out, a new method for selecting the driving electromotor is offered as well.