Kinematic and dynamic performance evaluation of a four degrees of freedom parallel robot

In this paper, the performance of a four degree of freedom parallel manipulator with Schönflies motion is evaluated from kinematic and dynamic points of view. Its low inertia makes it a suitable choice for pick-and-place applications, which demand high velocity and acceleration. So, the dynamic characteristics of the robot are of high importance. Moreover, parallel robots suffer from a small workspace, on which their singularities put additional constrain. Hence, this paper studies the kinematic and dynamic behavior of the robot in-depth to give a clear perspective to path planning and its applications. To perform kinematic analysis, constraint equations are derived based on the geometric method, and then Jacobian matrices are determined via velocity analysis. By considering the constraint equations and joint limits, reachable workspace is determined applying point-to-point search algorithm and singularities are identified by the inverse and direct Jacobian matrices. For dynamic modeling, Euler-Lagrange formulation is applied and both kinematic and dynamic models are verified by the results obtained from mechanism simulation in ADAMS software. Furthermore, for evaluation of the robot performance, pressure angles are employed to show the equality of motion/force transmission, and dynamic indices based on joint space inertia matrix are applied to illustrate its dynamic behavior.