Lap time simulation for racing car design

• Main Author: Siegler, Blake
• Other Authors: Crolla, D.
• Published: University of Leeds 2002
• Subjects: 629.228
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.443945

Racing teams use numerous computational tools (CAD, FEA, CFD) to aid in the design of racing cars and the development of their performance. Computer simulation of racing car handling through Lap Time Simulation (LTS) packages complements these tools. It also allows teams to examine the effect of different vehicle parameter setups to optimise vehicle performance. In similarity with the automotive industry, time is limited and rapid development of new ideas and technology is essential. Thus, the use of a more sophisticated computer simulation would allow a team to gain a significant advantage over their competitors. As LTS are computationally intensive,previous packages have simulateda full lap using a quasi-static method which splits the path of the vehicle into segments. An analysis is then made of the vehicle at each segment point using the external forces acting on the vehicle. Due to the constant acceleration(i.e. steady state) assumption across each segment, this method does not take into account the effect of roll, pitch and yaw inertia as well as damping and tyre lag effects. Another aspect that is not accounted for is the variation in the fastest effective vehicle path along the circuit (i.e.racing line) due to change in driver control inputs or vehicle parameters. The overall aim of this thesis is to develop a transient LTS methodology, which adopts a strategy to vary the racing line taken in order to address the problems found with the existing quasi-static LTS packages. In parallel an investigation of the accuracy of vehicle models in relationship to racing car performance has been developed. The thesis begins with a study of racing car modelling techniques and a review of current LTS packages. A description is then given of the collection of vehicle handlingd ataf rom an actualr acingc ar (alongw ith attaining a vehicle parametesr et) and the measured results displayed and discussed. The creation of two vehicle models, a simple and sophisticated version, is detailed and the measured results are compared to the simulated results of each vehicle model. It was found that the simple vehicle model does not fully represent the actual vehicle's lateral dynamic behaviour, although its steady state response was deemed to be accurate. The sophisticated vehicle model was seen to not only accurately predict the full range of lateral dynamic behaviour of the actual vehicle, but also the actual vehicle's longitudinal and combined lateral and longitudinal dynamic behaviour. To further investigate LTS techniques, a comparison study was made between various simulation approaches which indicated that the transient approach, although more complicated and time consuming, allows for more accurate tuning of a greater number of vehicle parameters. Finally, the creation of two simulation packages has been detailed and case studies are presented to provide further insight into the look and feel of the packages. The first package is a quasi-static approach based LTS package, where a case study is made into the sensitivity of overall lap time to a range of vehicle parameters. The second is a transient approach based simulation package which optimises the driver controls,varying the racing line taken by the vehicle and ensuring the manoeuvre is completed in the quickest time for that vehicle parameter set. This final Manoeuvre Time Minimisation package fulfils the overall aim of the thesis and a case study is made into the effect of front damping value on manoeuvre completion time.