For the mechanisation or automation of mining, recognition of the shape of mined cavities is basic information. A three dimensional shape measuring system, developed and tested, includes an ultrasonic range finder which is attached to the tip of a serial link manipulator. The range finder can be moved to any position and direction in the operational space of the manipulator. The position of a point on the surface of the object is obtained from the position of the range finder, the direction of the beam of the ultrasonic waves and the measuring distance of the range finder._x000D_
To avoid collision between the sensor and the object, the manipulator is controlled to trace the surface of the object For the tracing control, another ultrasonic range finder is employed._x000D_
The test results show that the developed system has high performance.