Research Of Motion Control For3-dof Imitating Ape Double Arms Robot Underactuated Grasping Objective Rod

In this paper,we imitate the movement process of ape brachiating frombranch to branch. we designed a new type of3-DOF underactuated mobilerobot，brachiating can be equivalent to movement of grasping target bar.Whenthe mobile robot grasps the bar,there is no actuator to dirve the robot movearound the bar, and the joint constitutes a underactuated joint. So how to drivethe robot to move forward to grasp target bar accurately and reliably becomes adifficult problem.First we analyzes the movement of3-DOF underactuated robot in trussenvirment.We increase the wrist joint structure base on the two linkunderactuated robot in our lab.and modify the friction wheel transmissionmechanism to measure the rotaion angle between the underacted hand and thebar,to make it constitute3-dof underactuated robotSencondly, we analysis the kinematics about the3-DOF underactuated robot,and the motion process is divided into swing up and grasping twostages.According the stages we divided, establish the dynamics model of thesystem by using the method of Lagrange equation.Then we proposes a new control strategy. Swing up stage adoptedparametric excitation strategy, we get the optimal trajectory by using the methodof nonlinear optimization for achieving swing up rapidly.Grasping stage webuilded big damping method to make the robot constitutes a big dampingnonholonomic constraint state, and the robot rotate slowly, driving the elbow andwrist joint compensate displacement to achieve grasping the targeting barreliably.Finally the movement simulation is completed with Matlab and ADAMSsoftware, the simulation result indicate the control strategy we purposed can make the robot grasping the targeting bar reliably, providing a new direction forresearch of this kind of robot.