| Popis: |
One of the most important concepts in motorsport is vehicle dynamics. Being able to predict the manoeuvre behaviour of a racing vehicle, not only reduces test time but also optimizes the development process. Once it is possible to isolate external factors, one can study a particular group of variables and anticipate their consequence on the overall vehicle performance. This work is focused on two different approaches to the problem of predicting vehicle behaviour. The first procedure consisted in the development of a simulation tool, more precisely, a Lap Time Simulator using Simulink. Given the specific requirements of the team, the simulator was built without the use of any predefined vehicle dynamics block sets, this means, the algorithm is fully customizable. The developed simulator uses a single point mass approach, so the vehicle body was converted to a single point neglecting the effects of body roll and load transfer. Nevertheless, the algorithm can predict the effects of different vehicle systems on lap time. The calculations include, for example, a powertrain model defined by engine torque, gear ratios, rotational inertia and fuel consumption. The aerodynamic module controls the negative lift and drag force present at each step. The tyre behaviour was defined by a basic tyre model, which predicts longitudinal, lateral and rolling resistance forces. The second method utilizes a commercially available solution using a quasi-steadystate approach with optional transient properties. Instead of a single point mass, the vehicle body model uses a four-track model with the motion of each wheel/suspension to formulate the vehicle manoeuvre. The tyre model was extended to include slip angle, slip ratio and combined slip. For that purpose, the software utilizes the Pacejka magic formula with formula student tyre data. One of the most important factors of simulation tools is the validation of the results. For that reason, the thesis also includes an experimental procedure regarding the behaviour of a formula student on a controlled environment track. The obtained data were used to compare the simulation results with the real logged data provided by a vehicle instrumentation apparatus. |
