Design and Analysis of a Quick-Action 3DOF Parallel Manipulator Based on Linkage Systems

Abstract

We propose a three degree of freedoms (DOFs) parallel manipulator, which is composed of four quick action linkage mechanism with high speed CAM. The CAM is designed by using a $7^{th}$ degree polynomial curve, which can realize the dwell-rise-dwell motion. In the return phase, the beginning point and ending point in rise phase are connected by a line segment. To have continuous velocity and acceleration of CAM-follower in the whole movements, a non-uniform rational b-splines (NURBS) curve is used to optimize the polynomial curve and the connected line segment.

Based on this CAM, a quick action linkage mechanism is proposed to realize fast-out and slow-back. We assumed that the length of all the links are given, and the range of link parameters are determined in detail. According to these link lengths and their parameters, forward kinematics and inverse kinematics of this mechanism are proceeded to define its workspace and analyze the movements. Static forces and dynamics model are considered to analyze the forces applied to this mechanism.

By arranging four quick action linkage mechanisms in a way of quadrantal symmetry, a three DOFs quick action parallel manipulator is developed. It can move along $Z$ axis, and rotate along $X$ and $Y$ axis. To realize these movements, output platform of this manipulator has four groups of grooves which has two mutually perpendicular grooves with a intersection point. The previously proposed linkage mechanism is extended by adding two revolution joints in the end effector to connect with the output platform. Position analysis of this manipulator is done to obtained the position of output platform in forward case and the joint angles in the reverse case with given pose of the platform. First-order kinematics of this manipulator is also done to analyze its velocity in these movements.

To validate the designed quick action linkage mechanism, the motion trajectory of all the links are drawn with a simulated trajectory of end-effector. The values of all the joint parameters in both fast-out phase and slow-back phase are shown. Validation of parallel manipulator is done by showing the simulation results of its output actions, and the joint angles in the three types of movements. In addition, the application of developed linkage mechanism and parallel manipulator is analyzed and illustrated.