Dynamics Formulation and Optimization Algorithm for External Force Interaction and Motion Generation in a Welding Robot Manipulator

摘要

This paper studies the modeling and simulation method of a robot manipulator with external force interaction. We analyze a welding robot manipulator that is used for building box girders in an offshore plant. The robot platform has six degrees of freedom and all rotational joints. To build a mechanical structure of the robot manipulator, the DH (Denavit-Hartenberg) method is used, and the equations of motion driven by the Lagrange’s formulation with external force are implemented. The external force interacting with the robot platform is modeled as a mass-spring-damper system. The joint angle profiles of the robot manipulator parameterized with B-spline function approximation are the variables of optimization. The objective function is the summation of joint torque squares, and it is equally weighted for each joint. For constraints, joint angle limits; joint torque limits; collision avoidance; continuity condition; and the position, velocity, and orientation of end effector are imposed. Using the optimization-based modeling and simulation method, we can obtain all information related to the joint space, such as joint angle profiles, joint velocity profiles, and joint torque profiles under the external force interaction condition.