| Hydraulic actuator is key part of automobiles to realize driving,braking,and steering.Its structure and performance directly affect automobile performance With the growing requirements of automobile intelligence,electrification and integration,the shortcomings of traditional hydraulic actuators have become increasingly prominent.In terms of structure,due to the use of electronic valves to achieve pressure control,a valve body with heavier weight and bigger size is required;in terms of performance,larger energy loss occurs when liquid medium passes through electronic valves.At the same time,the cost of high-speed solenoid valves is also higher.Therefore,an advanced actuator is needed to meet the growing requirements in structure and performance.Aiming at multi-plate clutch in automatic transmission,this paper proposes a configuration and design scheme of electro-hydraulic actuator.Its significant advantages are simple structure,light weight,small size,and high efficiency.At the same time,taking this multi-disc clutch hydraulic actuator as research subject,through the research and analysis of existing nonlinear control methods,a model-based nonlinear triple-step controller is designed to achieve precise pressure tracking control.And then realize the engagement and disengagement of the multi-plate clutch.This paper verifies the advantages of this nonlinear control method compared to PID controllers through structure design,modeling and simulation,bench design,and rapid prototype verification analysis.Specific research contents of this article are as follows:1.A hydraulic actuator is designed according to the design requirements of multi-plate clutch actuator.The hydraulic actuator adopts a pump control method.The main components include an electric-direct-drive brush motor,a constant volume external gear pump,a highly integrated valve body,a hydraulic release bearing,and a multi-disc clutch.Firstly,select components with appropriate parameters through comparison and analysis.Secondly,design the valve body structure,internal oil circuit,and other connecting components of the actuator,and finally select the hydraulic sensor and displacement sensor with appropriate measurement range and high accuracy.2.For each components of the actuator,mathematical model is obtained.And the actuator mathematical model is derived.Through the dimensional analysis and physical meaning analysis of each item,the rationality of the established model is verified.Then use AMESim to build the physical model of the system in order to analyze the influence of different parameters in the mathematical model on system pressure.Then the mathematical model is simplified through reasonable assumptions.3.Based on the analysis and comparison of existing nonlinear control methods,a model-based nonlinear triple-step controller is designed.And Lyapunov second stability law proves that the control algorithm has certain robustness.The controller is modeled and simulated in Matlab/Simulink.Through typical test signal input,the nonlinear triple-step controller is compared with PID controller.Simulation results show that the model-based nonlinear triple-step controller has higher control accuracy and faster response speed.4.Test bench for this actuator is established,and open-loop and closed-loop experiments based on Xpc Target are conducted.Through diffident pressure signal input,pressure control results of the non-linear triple-step controller and the PID controller are compared.Experimental results show that the model-based nonlinear triple-step controller not only inherits the advantages of PID controller,but also reduces the workload of system calibration.And the model-based nonlinear triple-step controller can reflect the dynamic characteristics of the system with faster response,less volatility,smaller steady-state error. |
PDF Full Text Request