LabCar2-Based AT Hardware-in-loop Simulation System Development

As the development of automotive technology, people are having higher requirement of vehicle performance. Not only the vehicle should be powerful, but also the vehicle should be handled easily and comfortable. The application of automatic transmission can exactly meet above requirements, and it plays an important role in vehicle electronic development. The development of Automatic transmission control unit (TCU) should involve more technology, such as mechanical, electronic, hydraulic and computer hardware and software. In the TCU initial development phase, a lot of tests should be carried out to research the control logic, which will cost a lot of money and a long development cycle. In addition, the control algorithm is not perfect which may have some risks to the test people. So it is very necessary to introduce a development tool or technology to resolve above problems.Hardware in the loop simulation system is put forward in this article. With this technique the controller was integrated into the whole simulation system. Interconnection of input and output ports is to converse digital signals and analog signals. The simulation platform can emulate the real vehicle in various working condition and help the AT development in lab environment. The AT model consists of torque converter model, planetary gear transmission system model, hydraulic pressure model and vehicle dynamic model. Hydraulic can control the shifting process accurately, but the development of it is very complex and has a stringent requirement on working condition. In this article the hydraulic model was simplified by getting the relationship between hydraulic pressure and solenoid current and transforming the torque according to the clutch characteristic. The modeling of torque converter and planetary gears transmission system were described in details. Then the AT model was integrated into the whole vehicle model. The comparison between the result of simulation and real vehicle data showed that this simulation system can basically meet all the requirement of real system. By now this LabCar2-based simulation system was applied into the TCU development. The whole content can be divided into four parts, below were the details:Part 1, First, briefly enumerated the advantages and components of computer simulation, and based on above, hardware in the loop simulation system is introduced and placed an important role in electrical unit development; Second, the AT hardware in loop technique developed locally and abroad are summarized, based on which the LabCar2 based hardware in the loop simulation is introduced, which is the main research of the paper. Finally, this part gives a short description about the hardware, software and interfaces of LabCar2 and summarizes the main content of this article. Part 2, this portion is the key part of this article. The development of LabCar2-based AT models were described detailed .This part consists of two chapters. In chapter 2, toque converter modeling based on LabCar2 is performed. First, briefly analyzed components, working and lock methodology of toque converter. And then, the characteristic of torque converter output is got through experiment and applied in establishing the static mathematic model .the modeling is divided into two modes: push mode and pull mode. Finally, ASPIL language is used to change the mathematic model of toque converter into simulation model.In chapter 3, planetary gears transmission system model is built based on LabCar2. First, analyzed different components of planetary gears transmission system and different coupling mode of brake and clutch. Second, based on the analysis of modeling method of planetary gears local and abroad, the planetary gears mode is built with conventional math modeling method. The modeling consists of static model in which the gear is hold, and dynamic mode in which the gear is shifting. Three portions are implemented in the modeling, one is gear ratio calculation during gear shifting; the second is toque flow of transmission system, and the third is converting the toque flow to rotation speed information, which is used in other models. As mentioned above, the modeling of hydraulic is been simpled. Finally, ASPIL language is used to change the mathematic model of planetary gears transmission system into simulation model.Part 3, replacing the MT model in whole vehicle model with the AT model developed in part 2. First, the whole vehicle model was divided into several sub layers; the function and interface of each sub layer is described and .Later, this section analyzed the interface between AT model and other models and modified the AT model related sub models' parameters and procedures. Shifting decision model was added in the driver model. Finally the communication methods were defined and the hardware channels were assigned and modified.Part 4, this part is to validate the AT hardware in the loop simulation system. First, analyzed the component of HIL simulation system and the process of simultion,then defined the interface of hardware and software to structure of LabCar2-based AT hardware in the loop simulation system.Second,downloaded the AT model into the labCar2 simulation platform, then planed the method to validate the system. Finically, by comparison with real vehicle data, the accuracy and feasibility of the LabCar2-based AT hardware in loop simulation system is checked.The application of AT LabCar2-based hardware in the loop simulation proved it is possible that the development of TCU with less cost and short product cycle. The engineering of AT development will benefits from the research of this article.