| The swash-plate type hydrostatic axial-piston pump is broadly used as a power supply for hydrostatic systems. Since very large forces and moments are acting on the swash-plate to dislocate its position, a large and massive control actuator is required for adequate control. In light of these inherent disadvantages of the conventional control mechanism, it is desirable to replace this design altogether with another device that is smaller, less costly, more efficient, and more dynamically preferred. This research deals with a new control mechanism to replace the conventional control mechanism, and a variable indexed valve plate is considered to modify pressure translations within the pump. The torque acting on the swash-plate is modified by the indexing valve plate; this torque is obtained through a single piston chamber. A reduced order model is obtained to decrease the complexities of the pump dynamics, using the pressure carry-over concept, based on approximated pressure distribution along the valve plate. Both open-loop and parametric studies provide insights which are useful for system identification and control.; The observations and insights about the dynamics of the swash-plate are used to develop preliminary control strategies. The preliminary control consists of the regulator design and the estimator design. The regulator design is based on the pole placement technique. Average gain and the gain scheduling techniques are discussed for a feedback control. The full nonlinear and the reduced order models are compared. Noise is considered in the estimator design, and the level of acceptable noise is determined using simulations. Accuracy and performance of the control design are also evaluated using simulations, emphasizing their limitations. |
