Research On Control Software Of Automatic Mechanical Transmission

With the development of the theory and technology of the vehicle automatic transmission, automatic transmission vehicles will bring more and more convenience, comfort and safety to people’s lives and production. The technology of Automated Mechanical Transmission (AMT) has automatic transmission’s features, and it’s easy to operate and it can significantly reduce driver’s pilot work. Meanwhile due to using traditional manual transmission, AMT has characteristics such as easy to produce, low-cost to reform, high fuel efficiency and so on. AMT is ideal for China current conditions, and has broad market prospect.The thesis analyzes the shortcomings of the traditional AMT control software, and put forward AMT control software development based on the embedded real-time operating system FreeRTOS. Combining with school-enterprise project, and on purpose to practical application, the thesis analyses functions, plans the framework of the AMT control software, and improves control logic through the bench and road tests repeatedly. The work done in the thesis is as follows:(1) Functional analysis and framework plan for AMT control software.From the view of functional analysis, the thesis decomposes the final AMT system driving function into specific, relatively independent function modules, and explores the implementation of these functions and potential difficulties. This work basically determines software’s content and implementation steps.The thesis describes the hierarchical frameworks of the AMT control software, as well as the main function of each layer. Several tasks are divided based on operating system, and each task achieves certain functions. Monitor task is emphatically introduced because it plays the role of manage layer. The logic of manage layer divide vehicle state into five major categories. Then the thesis describes the conditions of each category and the control logic for each category.(2) Software development environment development and the PID control algorithm achievement.FreeRTOS is an open source, free, lightweight, real-time operating system, which provides a variety of functions such as task management, task scheduling, communication and resource sharing mechanisms; STM32F103VE is the major chip in TCU, which Cortex-M3core inside, and its resources and usage conditions can meet the requirements of the TCU; The thesis emphatically introduce how to transplant FreeRTOS into the STM32microprocessors.AMT system uses12V DC motors to drive the four actuating mechanism such as select gear, shift gear, clutch and throttle, and the PWM technology is used to control and drive DC motors; AMT control software adopts the PID control algorithm for the position control and motion control of actuating mechanism; The thesis explains P, I, D three parts function and introduces specific forms of PID control method in the AMT control software and its debugging process.(3) AMT control software function achievement and improvement.According to the idea of functional analysis, the thesis describes main functions and debugging process. This functions include:Digital, analog and frequency signals acquisition and processing; Gear judgment and the except gear handling mechanism; Gear switching process analysis, and selecting, shifting path planning; LED display function and Communication function between PC and TCU; Start-up and crawl functions, mainly about clutch and throttle control logic; Gear switching function on the road, selecting gear, shifting gear, clutch and throttle control logic, especially the coordination between clutch and throttle; Dynamic performance and fuel economy shift schedule, how to reflect the driver’s intention, and how to determine road conditions.(4) Bench and road tests.The bench tests are mainly used to debug the actuating mechanism PID control algorithm, and verify the feasibility of logic of gear switching, start-up and gear switching on the road the road. The road tests are mainly used to improve the control logic of the AMT control software, to improve the performance of the AMT system. By listing a large number of data curves, the thesis illustrates the practical effect of control logic in diesel vehicles and gasoline vehicles.