CARDAN JOINTS WITH AXIS OFFSET IN SINGULARITY FREE HEXAPOD STRUCTURES FOR NANOMETER RESOLUTION

摘要

The main advantages of hexapod systems are user-friendly compact shipment design and high stiffness. An improvement in the accuracy of hexapod systems can be achieved via better actuator/sensor, cable outlet and joint design. For most applications the use of external 6 DOF sensor systems at the platform is not suitable due to the sensor performance, the size or the price of such sensor systems. Therefore, sensor systems inside the struts have to be used as a reference for each single axis of the hexapod. The platform position will be determined by the strut-sensor systems, the joints - and the mechanical tolerances (which can be calibrated). This paper describes different joints used in nanometer repeatable, parallel-kinematic systems. Such joint designs require large computing power of the controller.