Mobile hydraulic equipment are today operated manually to a very large extent. There are, however, some applications where substantial benefits would be obtaind if some kind of feedback and more sophisticated control was used. One such application is the control of a crane. Usually the operator controlls the flow to each of the pistons so that the crane tip is moved in the desired direction (Fig. 1). Since many mobile hydraulic valves packages have electronic input and there exists built in position transducers for the pistons, it seems to be rather straightforward to introduce vector control of the crane tip directly. That is, the operator commands controlls the direction and speed of the crane tip. Here, a control algorithm is described that allows the use of mobile electrohydraulic proportional valves while still having accurate vector control of the crane tip.
