Parallel robot design incorporating a direct end effector sensing system

Abstract

For many parallel robots, the exact position in space of the end effector or tool head cannot be sensed directly. They operate under overall 'open loop' control as the software controlling the machine makes a calculated estimate of where the tool head should be. This is done by monitoring sensors on axes that track linear translation and rotations of shafts/gears. For low precision applications, this system is appropriate. However, positional errors can occur and accumulate. There exists a need for a sensor system that is capable of acquiring the exact spatial coordinates of the tool point or end effector directly.