Modeling and Controlling for Hydraulic Excavator's Arm

Abstract

Abstract-Controlling of excavator's arm is an important and basic task in autonomous research of hydraulic excavator at present, but the behavior of the excavator's arm is dominated by the nonlinear dynamics of the hydraulic actuators. To find a feasible way to control excavator's arm and realize autonomous excavation, firstly, Full kinematic and dynamic models of the excavator arm, regarded as a planar manipulator with three degrees (boom, dipper and bucket) of freedom, were derived, the exponential product formula based on screw theory was used in kinematic model, by which objective angular series of the working mechanism was connected with the desired trajectory of the bucket, and the Lagrange equation was used in dynamic model. secondly, because the experimental excavator's LUDV hydraulic system was not fit for computer control, so the excavator was retrofitted with electrohydraulic proportional valves, associated sensors (three inclinometers), and a computer control system(the motion controller of EPEC), the retrofitted excavator could allow experimental evaluation and refinement of the developed controllers, then ,the full nonlinear math model of electrohydraulic proportional system was achieved; These models included detailed representation of the electrohydraulic actuation system to obtain structural insight into the dynamic behavior of the system; thirdly, According to the highly system dynamic, and parameters uncertainties, external disturbance, the dead region and nonlinear gain coefficient of the proportional direction valve, this paper presents a discontinuous projection based on an adaptive robust controller to approximate the nonlinear gain coefficient of the valve and the nonlinear of the whole system, the error is deal with robust feedback and an adaptive robust controller was designed. Finally, the experiment of the boom motion control is presented to illustrate the feasibility. The thesis covered some phases from modeling to theoretical analysis of controller designs, and to implementation and experimental validation of the new control schemes. These efforts had resulted in new control design methodologies that were applicable to several hydraulic proportional systems when high control performance is required in the presence of severe nonlinearity and uncertainty.