Real time full circuit driving simulation system

[摘要] ENGLISH ABSTRACT: The requirements regarding the quality of engines and vehicles have increasedconstantly, requiring more and more sophisticated engine testing. At the same time,there is a strong demand to reduce lead time and cost of development. For many yearssteady state engine testing was the norm using standard principles of powerabsorption. Since the mid 1980's increasing importance has been attached to theoptimisation of transient engine characteristics and the simulation of dynamic realworld driving situations on engine test stands. This has led to the use of bi-directionalDC or AC regenerative dynamometers a practice now known as dynamic enginetesting.Interfacing a computer with vehicle simulation software to an engine on a dynamictest stand and using hardware in the loop techniques, enables the simulation of realworld driving situations in a test facility. In dynamic engine testing a distinction canbe made between simulation testing and transient testing. In simulation testing the setpoint values are predetermined whereas in transient testing a model generates setpoint values in real time. Speeds and loads are calculated in real time on the basis ofreal time measurements. The model can be in the form of a human or driversimulation.This project involved the application of dynamic engine testing to simulating a racingapplication. It is termed Real Time Full Circuit Driving Simulation System due to thesimulation of a race car circling a race track, controlled by a driver model and runningthe engine on a dynamic test bench in real time using hardware in the looptechniques. By measuring the simulated lap times for a certain engine configurationon the test bench in real time, it is possible to select the optimal engine set-up forevery circuit. The real time nature of the simulation subjects the engine on the testbench to similar load and speed conditions as experienced by its racing counterpart inthe race car yielding relevant results. The racing simulation was achieved by finding asuitable dynamic vehicle model and a three dimensional race track model, developinga control strategy, programming the software and testing the complete system on adynamic test stand.In order to verify the simulation results it was necessary to conduct actual tracktesting on a representative vehicle. A professional racing driver completed threeflying laps of the Killarney racing circuit in a vehicle fitted with various sensorsincluding three axis orientation and acceleration sensors, a GPS and an engine controlunit emulator for capturing engine data. This included lap time, vehicle accelerations,engine speed and manifold pressure, an indicator of driver input. The results obtainedfrom the real time circuit simulation were compared to actual track data and theresults showed good correlation.By changing the physical engine configuration in the hardware and gear ratios in thesoftware, comparative capabilities of the system were evaluated. Again satisfactoryresults were obtained with the system clearly showing which configuration was bestsuited for a certain race track. This satisfies the modem trend of minimizing costs anddevelopment time and proved the value of the system as a suitable engineering toolfor racing engine and drive train optimisation. The Real Time Full Circuit Driving Simulation System opened the door to furtherdevelopment in other areas of simulation. One such area is the driveability of avehicle. By expanding the model it would be possible to evaluate previouslysubjective characteristics of a vehicle in a more objective manner.

[发布机构] Stellenbosch University