Analysis of an controller design for an electro-hydraulic servo pressure regulator

Mobile hydraulics is in a transition phase, where electronic sensors and digital signal processors are starting to become standard on a high number of machines, hereby replacing hydraulic pilot lines and oering new possibilities with regard to both control and feasibility. For controlling some of the existing hydraulic components there are, however, still a need for being able to generate a hydraulic pilot pressure, as e.g. almost all open-circuit pumps are hydraulically controlled. The focus of the current paper is therefore on the analysis and controller design an electro-hydraulic servo pressure regulator, which generates a hydraulic LS-pressure based on an electrical reference, hereby synergistically integrating knowledge from all parts of the mechatronics area.

The servo pressure regulator is used to generate the LS-signal for a variable displacement pump, and the paper rst presents the considered system and an experimentally veried model of this. A linearized model is then presented, which comprise the basis for a stability and sensitivity analysis of the system. Based on the results of the analysis, a control strategy is designed in combination with optimisation of the mechanical design to generate a controlled leakage  ow that aids in stabilising the system. The robustness of the system is then discussed in relation to dierent pilot line volumes and pump dynamics. Finally experimental results are presented, where the performance is compared to that of a similar hydraulic reference system, which has been the basis for the specification of performance requirements.