In order to find a feasible way to control excavator’s arm and realize autonomous excavation, the dynamic model for the boom of excavator’s arm which was regarded as a planar manipulator with three degrees of freedo...In order to find a feasible way to control excavator’s arm and realize autonomous excavation, the dynamic model for the boom of excavator’s arm which was regarded as a planar manipulator with three degrees of freedom was constructed with Lagrange equation. The excavator was retrofitted with electrohydraulic proportional valves, associated sensors (three inclinometers) and a computer control system (the motion controller of EPEC). The full nonlinear mathematic model of electrohydraulic proportional system was achieved. A discontinuous projection based on an adaptive robust controller to approximate the nonlinear gain coefficient of the valve was presented to deal with the nonlinearity of the whole system, the error was dealt with by robust feedback and an adaptive robust controller was designed. The experiment results of the boom motion control show that, using the controller, good performance for tracking can be achieved, and the peak tracking error of boom angles is less than 4°.展开更多
The synchronous tracking control problem of a hydraulic parallel manipulator with six degrees of freedom (DOF) is complicated since the inclusion of hydraulic elements increases the order of the system.To solve this p...The synchronous tracking control problem of a hydraulic parallel manipulator with six degrees of freedom (DOF) is complicated since the inclusion of hydraulic elements increases the order of the system.To solve this problem,cascade control method with an inner/outer-loop control structure is used,which masks the hydraulic dynamics with the inner-loop so that the designed controller takes into account of both the mechanical dynamics and the hydraulic dynamics of the manipulator.Furthermore,a cross-coupling control approach is introduced to the synchronous tracking control of the manipulator.The position synchronization error is developed by considering motion synchronization between each actuator joint and its adjacent ones based on the synchronous goal.Then,with the feedback of both position error and synchronization error,the tracking is proven to guarantee that both the position errors and synchronization errors asymptotically converge to zero.Moreover,the effectiveness of the proposed approach is verified by the experimental results performed with a 6-DOF hydraulic parallel manipulator.展开更多
Existing hydraulic braking systems in the vehicle is composed of the brake pedal, the hydraulic booster and the hydraulic caliper. The driver transmits one＇s breaking intent through the brake pedal stroke and force. ...Existing hydraulic braking systems in the vehicle is composed of the brake pedal, the hydraulic booster and the hydraulic caliper. The driver transmits one＇s breaking intent through the brake pedal stroke and force. The hydraulic booster can amplify the pedal force, only when the engine operates. The hydraulic caliper is composed of cylinders, pistons. There are also hydraulic pipes from the booster to the caliper. Currently, X-By-Wire technology is researched actively due to the exhaustion of fuel and the regulation of CO2. As a chain of this trend, the e-pedal and an electric mechanical brake （EMB） also are highlighted. At the beginning of EMB development, high-torque and high-power motors are required in order to implement the existing hydraulic calipers＇ clamping force. This has some limits as the need of big spaces and high costs. Then the electro wedge brake （EWB） is launching with self-reinforcement features of the wedge structure. EWB can generate big clamping forces with small size and low-torque motors with good braking-efficiency. In recent, the disc＇s circumferential face clamping one has been researched, for better heat-emission ability and better braking-efficiency compared to the existing disc＇s lateral face clamping method. But, this circumferential face clamping method can have worse unbalance-wear features compared to lateral face clamping one. In this study, the authors describe their circumferential EWB concepts, the method for reducing unbalance-wear feature of circumferential EWB, and the cost-effective implementation of circumferential EWB, in particular focused on nonlinear counter-wedge profile which is appropriate to reduce unbalance-wear.展开更多
基金Project(2003AA430200) supported by the National Hi-Tech Research and Development Program(863) of China
文摘In order to find a feasible way to control excavator’s arm and realize autonomous excavation, the dynamic model for the boom of excavator’s arm which was regarded as a planar manipulator with three degrees of freedom was constructed with Lagrange equation. The excavator was retrofitted with electrohydraulic proportional valves, associated sensors (three inclinometers) and a computer control system (the motion controller of EPEC). The full nonlinear mathematic model of electrohydraulic proportional system was achieved. A discontinuous projection based on an adaptive robust controller to approximate the nonlinear gain coefficient of the valve was presented to deal with the nonlinearity of the whole system, the error was dealt with by robust feedback and an adaptive robust controller was designed. The experiment results of the boom motion control show that, using the controller, good performance for tracking can be achieved, and the peak tracking error of boom angles is less than 4°.
基金Project(50375139) supported by the National Natural Science Foundation of ChinaProject(NCET-04-0545) supported by the New Century Excellent Talent Plan of the Ministry of Education of China
文摘The synchronous tracking control problem of a hydraulic parallel manipulator with six degrees of freedom (DOF) is complicated since the inclusion of hydraulic elements increases the order of the system.To solve this problem,cascade control method with an inner/outer-loop control structure is used,which masks the hydraulic dynamics with the inner-loop so that the designed controller takes into account of both the mechanical dynamics and the hydraulic dynamics of the manipulator.Furthermore,a cross-coupling control approach is introduced to the synchronous tracking control of the manipulator.The position synchronization error is developed by considering motion synchronization between each actuator joint and its adjacent ones based on the synchronous goal.Then,with the feedback of both position error and synchronization error,the tracking is proven to guarantee that both the position errors and synchronization errors asymptotically converge to zero.Moreover,the effectiveness of the proposed approach is verified by the experimental results performed with a 6-DOF hydraulic parallel manipulator.
文摘Existing hydraulic braking systems in the vehicle is composed of the brake pedal, the hydraulic booster and the hydraulic caliper. The driver transmits one＇s breaking intent through the brake pedal stroke and force. The hydraulic booster can amplify the pedal force, only when the engine operates. The hydraulic caliper is composed of cylinders, pistons. There are also hydraulic pipes from the booster to the caliper. Currently, X-By-Wire technology is researched actively due to the exhaustion of fuel and the regulation of CO2. As a chain of this trend, the e-pedal and an electric mechanical brake （EMB） also are highlighted. At the beginning of EMB development, high-torque and high-power motors are required in order to implement the existing hydraulic calipers＇ clamping force. This has some limits as the need of big spaces and high costs. Then the electro wedge brake （EWB） is launching with self-reinforcement features of the wedge structure. EWB can generate big clamping forces with small size and low-torque motors with good braking-efficiency. In recent, the disc＇s circumferential face clamping one has been researched, for better heat-emission ability and better braking-efficiency compared to the existing disc＇s lateral face clamping method. But, this circumferential face clamping method can have worse unbalance-wear features compared to lateral face clamping one. In this study, the authors describe their circumferential EWB concepts, the method for reducing unbalance-wear feature of circumferential EWB, and the cost-effective implementation of circumferential EWB, in particular focused on nonlinear counter-wedge profile which is appropriate to reduce unbalance-wear.
