Research On Control Strategy Of Clamping And Lifting Mechanism Of Towbarless Aircraft Tractor

Aircraft tractors are very important ground handling equipment in airports.Towbarless aircraft tractor is the new type of aircraft tractor.The aircraft and tractor are fixed together by a clamping and lifting mechanism for towing movement,which is also the current development trend of tractors.The clamping and lifting mechanism is the actuator of the towbarless aircraft tractor.The tractor can tow through the clamping and lifting mechanism.Research on the control strategy of the clamping and lifting mechanism can ensure that the tractor can tow better.This article mainly starts the research from the force control strategy of the clamping hydraulic cylinder group and the position control strategy of the lifting hydraulic cylinder group。In order to design the clamping lifting mechanism,I have studied different configurations,analyzed the advantages and disadvantages of different configurations,evaluated the movement space,design difficulty,the number of required hydraulic cylinders and other indicators and selected the appropriate configuration.In view of the active compensation motion of the lifting hydraulic cylinder,the tilt of the nose landing gear in the turning process of the tractor pulling the aircraft is analyzed.The reason of the tilt of the landing gear is analyzed by using the load transfer theory,and the tilt Angle of the landing gear in the turning process of the aircraft is calculated.The stroke required for the active compensation of the lifting hydraulic cylinder is calculated.The hydraulic power mechanism is the most basic driving unit.Through the analysis of the functional requirements of the clamping hydraulic cylinder and the lifting hydraulic cylinder,the lifting hydraulic cylinder needs position control,and the clamping hydraulic cylinder needs force control.Therefore,the position control modeling of the lifting hydraulic cylinder and the force control modeling of the clamping hydraulic cylinder are carried out respectively.Considering the nonlinear nature of hydraulic power mechanism,the linear modeling and nonlinear modeling are carried out respectively,and the reasonable simplification is carried out for the convenience of analysis.The lifting hydraulic cylinder position controller design and clamping hydraulic cylinder force controller design and simulation analysis.The PID controller,fuzzy PID controller and sliding mode controller were designed respectively for the clamping hydraulic cylinder,and the control effects of the controllers were compared.In the process of designing the sliding mode controller,nonlinear algorithm was used to linearize the dynamic equation of the valve controlled cylinder.The PI force controller and the speed feedback regulation method of the clamping hydraulic cylinder are designed and compared.The co-simulation was conducted based on ADAMS model to verify the control effect of the controller.Establish the 3D model of tractor and aircraft,and assemble the model of traction system.Calculate the minimum turning radius and select the typical traction motion condition.The three-dimensional model of the traction system was imported into ADAMS,and the traction motion simulation was carried out using ADAMS to verify the analysis of load transfer theory on landing gear tilt in the turning process of the aircraft.The interface between MATLAB and ADAMS is set,and the controller simulation is carried out with ADAMS and Simulink to verify the control effect of the designed position controller and force controller.