Research On The Key Technologies Of Towbarless Tractor Based On The Hydrostatic Constant Pressure Network

Aircraft tractors, as important airport pavement support and guarantee vehicles, play an irreplaceable role in both the civil fields/area and the military fields/area. With the continuous development of air transportation, the demands/requirements of aircraft tractors'performance become higher and higher. Hydraulic transmission with the advantages of power density, wide range of continuously variable transmission, good performance in power braking, super capability for overload protection, convenient for power output shuttle, and so on, has become the mainstream transmission style."Paying equal attention to energy-saving and good performance"has become the important development direction of future automobile. Using the technology based on secondary regulation of hydraulic hybrid vehicles (HHV) in towbarless tractors is reasonable and feasible solution, which can regenerate the energy, reduce fuel consumption by adjusting the engine working points, and decrease harmful gas emissions. Based on the hydraulic hybrid concept, this vehicle utilizes the Wheel Driving/Braking technology. It runs in the hydraulic constant pressure network to parallel control each wheel independent driving/braking, which has accurate control property and sensitive control response; this point accords well with these characteristics where towbarless tractors need stable speed without shock, accurate and convenient control, good performance of power system and high control precision. Taking the hydraulic drive towbarless tractor which is based on the constant pressure network as the objective of this study, this dissertation makes a in-depth studies on about drive and brake control technology, assembly and parts key technology according to the theory of vehicle engineering.After consulting a lot of related literatures and reference materials at home and abroad, this paper summarized the development of aircraft tractor haulage pattern, linking device and transmission system, as well as the current research situation of configuration style in hydraulic hybrid technology both at home and abroad. This paper also analyzed the characteristics and the development of hydraulic constant pressure network technology and wheel driving technology comprehensively. On this basis, I proposed the technical formula for the towbarless tractors.This paper elaborated the operating principle of wheel drive hydraulic system based on constant pressure network; after analyzing the working condition characteristic of towbarless tractors, constraints of practical engineering, designation index of vehicle performance and the internal relations of power system components, according to the global optimization. The matching optimizations of main parameters were researched by adaptive simulated annealing genetic algorithm; according to the forward/backward modeling ideology, the rationality of optimization result verified by means of modular simulation software.According to the construction and the working condition characteristic of towbarless tractors, this paper analyzed the kinematics of steering and established the models of precision moment of resistance (regular resistance and additional resistance) in different working conditions. The mathematical model of vehicle control system was set up; under the constraint of vehicle parameter, taking the speed-steer wheel as input, setting the control target and coordination strategy of each wheel speed. The speed control of each wheel was researched by using radial basis function neural network sliding mode control (RBFNN). According to the braking requirements of power system, the coordination strategy of hydraulic regenerative braking was formulated. The friction braking allocated braking force reasonably according to the braking requirements of different wheels. In order to fully exert the utilization rate regenerative braking and component performance, different programs of braking system were analyzed and selected. According to the aim of braking speed of each wheel, braking control algorithm based on adaptive neural-fuzzy inference system (ANFIS) was conducted.In order to put scientific and technological achievements into practice, the general arrangement and relative technologies of towbarless tractors was researched. A constant pressure oil source was built, so as to reduce the load flow influence to the system pressure. The hydraulic subsystem principle design was made, including appropriate integration; to optimize and analyze the design of the clamp-lifting mechanism and the hydraulic system. The vehicle modular framework was established by making use of bus technology, and researched, so as to make engineering design about bus technology; model of the whole vehicle is also constructed and complete the design of the general arrangement.I researched on the simulation experimentation platform which is applied to hydraulic drive hybrid vehicles. Using the ideology of system parameter identification and parameter estimation algorithm based on improvement of particle swarm multivariate linear regression model, Research was carried out on part of parameters and characteristics of the experimentation platform. Meanwhile,another research on the platform was carried out in order to investigate the behavior of friction and damping coefficient under a method combining testing and data analysis. On this basis, relevant simulation and experimentation was conducted to verify the effectiveness of vehicle driving and braking control algorithm.