An enhanced ultrasonic system for robot end effector tracking

There is widespread interest in the development of improved robot manipulator controllers, especially in the area of controlling the oscillatory modes associated with high speed manipulators. The common aim of such controllers is to steer the motion of the robot arm such that the end-effector adheres closely to some pre-specified trajectory. In order to verify the performance of any new controller when implemented on a real robot, the motion of the end-effector must be measured in real time. The use of end-effector position as an input parameter to the controller is also highly desirable. The typically fast movement of the end-effector imposes a requirement that the data rate of any end-effector position measurement system to be high. At a typical end-effector tip velocity of 1m/s, the end-effector moves 10 mm between samples if the data rate is 100 Hz. The solution proposed in the paper is the use of an ultrasonic position measurement and tracking system.