Computer vision control of an underwater manipulator

This paper describes the philosophy applied for the control of a five degree of freedom, electrically driven manipulator mounted on a six degree of freedom remotely operated vehicle (Aquasphere). Guidance commands for the manipulator could be provided either by the operator, using joysticks, or from a 3D vision system which could determine the full position and orientation of objects. The range information was generated by a dual spot laser triangulation system which was capable of providing range and location information to an accuracy of ±2 mm. An alternative range finder based upon the time of flight system (TOF) is also discussed. Transputers were used as the processing elements to solve the inverse kinematics required for the manipulator whilst a hybrid dedicated hardware-transputer system was used for the image processing. Once the vehicle was placed in the vicinity of the object the complete system was demonstrated by using the vision system to locate and then autonomously guide the manipulator to retrieve the object