Parallel manipulators are closed-loop mechanical structures presenting very good performance in terms of accuracy, rigidity and ability to move large loads. Generally, the mechanism has two platforms: one is attached to the fixed reference frame and the other performs arbitrary motions in its workspace. Some moving legs similar to those of serial robots connect the moving platform to the fixed platform. Spherical joints, revolution joints or prismatic joints connect the elements of the robot to one another.
Recently, much effort has been devoted to the kinematic and dynamic analysis of fully parallel manipulators. The dynamic analysis was usually conducted by analytical methods of classical mechanics in which projection and resolution of equations on the reference axes are written in a considerable number of cumbersome, scalar relations and the solutions are rendered by large-scale computation together with time-consuming computer codes.
Pang Thae Jin, a researcher at the Robotics Institute, has established a new method for inverse dynamic analysis of a 3-DOF parallel manipulator with three actuators using an approach based on the principle of virtual work.
The new approach is far more efficient, and it can eliminate all forces of internal joints and directly determine the time-history evolution of torques and powers required by the three actuators.
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