Positioning Accuracy of a Parallel Kinematic Gantry-Tau Robot

Parallel robots are generally said to be more accurate and have a smaller workspace compared to serial robots. With the Gantry-Tau robot, a parallel robot with relatively large workspace was presented. This article examines the end-effector positioning accuracy of the Gantry-Tau robot. End-effector positioning errors arising from joint positioning or modeling errors are studied. A geometric approach is used and with the aid of linearization, the influence of the robot's pose and kinematic parameters on accuracy is studied. Simulations and evalutation of measurement data support the geometric results. The joint and end-effector accuracy of two different Gantry-Tau prototypes were evaluated. The work underlines the need of a very good actuator modeling and control