Control of Mobile Hydraulic Manipulators

The goal of the project is to develop a new valve based control scheme for mobile hydraulic manipulators, such as truck cranes or forest machines. This will comprise two parts, one will be the presentation of a new control strategy designed to increase the controllability of the manipulator, the other will be the presentation of a new type of Load Sensing system designed to increase the efficiency. The first part will present a new control strategy to improve the controllability of the manipulator, i.e. to make the job of the operator easier. This will be covered in four steps. The first step is the addition of pressure feedback to the flow controller to stabilize the system. The next step is the addition of an accelerometer to the manipulator to add damping and stiffness control. The third step is to develop a strategy to estimate parameters. The final step will be to put all the parts together on a multiple degree of freedom manipulator. The goal of the last step will be to implement end effect or velocity control. As an example a strategy to handle manipulator redundancy is developed. Results are reported through various papers and a PhD disserfation is expected 2003. The objective in developing a new Load Sensing (LS) system is to increase the efficiency of the hydraulic system. Often, LS systems measure pressure mechanically and adjust the power supply accordingly. However, with the emergence of new microcomputer controlled valves new opportunities arise. Since the valves are already microcomputer controlled, it is possible to make the LS system computer controlled. This opens possibilities for more efficient control schemes. Since sensors have been added to the valve it is now possible to measure pressure and calculate the flow through each valve. This information may be used to improve the LS system. The project is in cooperation with industry (Højbjerg Maskin Fabrik A/S, Hydrema A/S and Sauer-Danfoss A/S) giving an industrial focus and a theoretical focus. (Peder Pedersen; Marc Munzer; Sauer Danfoss A/S)