Research On Computer Test And Control System Of Automobile Chassis Dynamometer

The structure of auto is consummated gradually and performance of auto isenhanced gradually along with technology development. That is to say, Today theperformance of auto is to meet users' increasingly elevated require. It also ismended to gets to be perfect gradually. The main object about auto which ispursued by people is the security , stability, comfort and high-power. ABS, fourcycle turning, MCPU are adopted in auto. In a word, the development trend aboutauto is that pollution to environmental is less and less;fuel is consumed moreeconomical;security is better and better. On the one hand ,the require to auto whichis enhanced gradually promotes traditional auto technique to integrate modernelectron technique. And the economy-technique-standard about auto has beenimproved greatly in the last several decade. On the other hand, it promotes modernsynthesis performance testing technique to develop and apply abroad. So exploiturespeed about new auto is faster and control ability about new auto is advanced.Testing technique is the important part of modern manufacture technique. Itbases on traditional testing methods and develops to modern auto diagnosis andtesting technique along with electron technique and machining techniquedevelopment. Auto testing is to test auto status using modern testing technique andequipment and combining computer, autocontrol technique. It's a synthesisapplication science based on engineering math, fault physics, dependability theory ,electron and information control theory ,etc. Auto testing technique has animportant meaning to traffic security, protecting environment, advancing transportability and reducing production cost. So there is a realistic meaning to select autoperformance testing as research task.Auto drive capability is that auto overcomes all kinds of resistance to goforward. It includes most output wrest force, chassis output power, the highestspeed, speedup capability and climbing slope capability. These capabilities arecontrolled by engine power and transmission system, and also affected by airresistance. Auto drive capability is one of the main capabilities. It is directlyrelative to auto security , stability and comfort capability. So it is very important totest auto drive capability.The paper mainly research chassis-dynamometer power-measured machinesystem of auto testing line. Auto drive capability is the first main performance toassess, which is put forward in GB7258—1997 <>. It also puts forward the main technology condition and prescribestesting items and relative standard about auto drive capability. This paper designswhole scheme based on request and designs detailed system hardware and softwarebased on testing actual condition and technology request. It also expatiates on roadsimulation theory about power-measured machine and the control system adopted.The filter circuit and FIR filter are designed in order to remove and restraindisturbing signal. At last this paper data fitting and deals with the gathered data.This paper is divided to three parts.The first part introduces automobilechassis-dynamometer road simulation theory. Firstly, this part introduces the basistheory of automobile chassis-dynamometer road simulation.Driving resistanceexists when auto is running on the road. The problem of auto driving resistancesimulation must be solved in order to simulate auto running road situation.Secondly, this part expatiates detailedly the resistance simulation theory and givesthe formulas at the time of accelerating testing , oil-consuming testing and slidetesting. At the same time the basic parameters to be tested about automobilechassis-dynamometer are given and the testing theory of the parameters is given inthis part. Automobile chassis-dynamometer is controlled in three ways, whichincludes constant speed control, constant wrest control and constant current control.The last of this part introduces the control system named double closed loopcontrol system of the whole system, which the inner is current loop and outer isspeed loop or wrest loop. The PI modulation is adopted in order to advance thetracked speed and real time. Simulation is done using Simulink in order to explainthe superiority and feasibility of the double closed loop system.The second part introduces the hardware and software of this system. Thehardware includes mainly PC machine, on-off I/O clip, A/D D/A interface board,F/V switch, low-pass confusion-resist filter, magnifying and shaping. In this systemPC machine takes charge to manage data, control instructions and run software. Sothe system hardware can be predigested to get to high effect. The hardwarefunction is to emit instructions via judging the current state of automobilechassis-dynamometer based on current testing require. In this way the automobilechassis-dynamometer can work under current state. When auto gets to the rightplace , PC machine emits instructions to start to gather the data and deal with them.At last the result data will be printed.The software of the system adopts blocking design on the basis of systemdesign request. That is to say, if any one logic part of the software was changed, itwill not affect other parts. And any module can be transferred by other modules.The software of whole automatism testing system includes data-gathered module,most power-measured module, testing input power at constant speed module,accelerating testing module, slide distance and time module, oil-fed test module,speedometer testing module and engine exhaust emissions module, etc.The third part is about data management. The signals used in computer testingoften contain error signals. It are the main problems of data management to how towipe off the errors from the signals and how to reduce errors contained by testingresult. This part introduce mainly least square method among curve fitting,whichcan be used to revise system errors. This part also introduces FIR filter. A low-passfilter is designed using Hamming windows function to filter the errors. Simulationis done using Matlab in order to prove the feasibility of the low-pass filter. And theresult shows that the low-pass filter designed in the system can be satisfied.The research is on the basis of theory and completed via locale debugging andexperiments on the lab. The automobile chassis-dynamometer designed in thispaper has the merit of high precision, dependability and real time and gets bettereffect. It also has important meaning to test auto drive capability and testingequipment development...