Development Of Motor Vehicles Testers For Steering Force And Steering Angle Based On ARM9

The car is the most important means of transportation. As the development of vehicleindustry, the vehicle population is increasing rapidly, which brings to two serious problems,more traffic accidents and worse environment pollution. To solve these two problems, wecan take measures from two aspects. Firstly, improve vehicles’ capacities when produced.On the other hand, the performances of vehicles should be detected comprehensively,timely and accurately to prevent and process faults which may cause the above two seriousproblems.The handling and stability influences vehicles’ performance deeply, and the steeringwheel is one of the most important parts of vehicles. The maximum steering force andfree steering angle of steering wheels should be checked regularly by the steering forceand steering angle testers to meet the national standards. However, the existing detectorsare inconvenient to install, complex to manipulate, and poor accurate.This paper aims to develop a kind of steering force and steering angle testers whichare installed conveniently, manipulated simply and high accurate. The main work of thispaper is divided into the following sections.1.Analyse the influence of encoder’s installing eccentricity on steering angle testaccuracy based on the established analysis model, and build theoretical basis of steeringangle test. Analyse the torque error quantitatively caused by force sensor’s installingposition based on established analysis model. Determine that the force sensors are installedon the circle which has a diameter of420mm.Adopt the installing design scheme namedthe double telescopic jibs, which could decrease the eccentricity as small as possible.Design the mechanical structure of the tester, and draw a three-dimensional model of thedesigned mechanical structure by Solidworks. Then simulate the moving states. Designlocking mechanisms to keep the structure firmly.2.Use double-hole-cantilever girder-pressure transducer to test steering force andCHA-200BM-G12E incremental encoder to test steering angle. And build steering forcesignal acquisition, amplification circuits, the encoder pulse signal acquisition circuit andother peripheral circuits, which is much smaller than the circuits in existing testers. AdoptARM structure S3C2440chip as the CPU which has high processing speed and complete functional modules. Make optimal design of the interface circuit between S3C2440andLCD with touch screen. With all the above modules, build a hardware system which hashigh processing speed, stable performance, complete functions and small size.3.Program the steering force signal acquisition and AD conversion processingprograms using C language, then use AXD software debugging these programs online toget the digital value of steering force. In the same way, program encoder pulse signalacquisition and processing programs to get the digital value of steering angle. Port U-bootLinux kernel and File system suitable for the designed tester. Write A/D conversion and I/Ocontrol drivers, then load them into the Linux kernel. By running the test, find that theLinux kernel has good stability and small size which are very suitable for portable devices.Develop the overall application software, including calibration program and test program,achieving steering force and steering angle multi-point sequential test and other innovationfunctions with good human machine interface.4.Calibrate the steering force and steering angle in sectional type which can increasethe accuracy of testers. Design experiments to verify accuracy and linearity of steeringforce and steering angle test, which proves the results meeting the national standards.