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Technical Paper

Lap Time Simulation: Comparison of Steady State, Quasi- Static and Transient Racing Car Cornering Strategies

Considerable effort has gone into modelling the performance of the racing car by engineers in professional motorsport teams. The teams are using progressively more sophisticated quasi-static simulations to model vehicle performance. This allows optimisation of vehicle performance to be achieved in a more cost and time effective manner with a more efficient use of physical testing. Racing cars are driven at the limit of adhesion in the non-linear area of the vehicle's handling performance. Previous simulations have modelled the transient behaviour by approximating it with a quasi-static model which ignores dynamic effects, for example yaw damping. This paper describes a comparison between different cornering modelling strategies, including steady state, quasi-static and transient. The simulation results from the three strategies are compared and evaluated for their ability to model actual racing car behaviour.
Technical Paper

Integration of Active Suspension and Active Driveline to Improve Vehicle Dynamics

Many active control systems are developed as safety systems for passenger vehicles. These control systems usually focus on improving vehicle stability and safety while ignoring the effects on the vehicle driveability. In the motorsport environment, increased stability is desirable but not if the driveability of the vehicle is heavily compromised. In this work, active suspension and active drivelines are examined to improve vehicle dynamics and enhance driveability while maintaining stability. The active control systems are developed as separate driveability and stability controls and tested individually then integrated to create a multi-objective control system to improve both driveability and stability. The controllers are tested with standard vehicle manoeuvres.
Technical Paper

Integration of Active Suspension and Active Driveline to Ensure Stability While Improving Vehicle Dynamics

Most active control systems developed for passenger vehicles are developed as safety systems. These control systems usually focus on improving vehicle stability and safety while ignoring the effects on the vehicle driveability. While stability is the primary concern of these control systems the driveability of the vehicle is also an important consideration. An example of compromised driveability in a stability control system is brake based active yaw control. Brake based systems are very effective at stability control but can have a negative impact on the longitudinal dynamics of a vehicle. The objective of the vehicle control systems developed for the future will be to preserve vehicle driveability while ensuring the stability of the vehicle. In this work, active suspension and active drivelines are developed as stability control systems that have a minimal impact on the driveability of the vehicle.
Technical Paper

Improving Performance of a 6×6 Off-Road Vehicle Through Individual Wheel Control

This paper presents a method of control for a 6×6 series-configured Hybrid Electric Off-road Vehicle (HEOV). The vehicle concerned is an eight-tonne logistics support vehicle which utilizes Hub Mounted Electric Drives (HMED) at each of its six wheel stations. This set-up allows Individual Wheel Control (IWC) to be implemented to improve vehicle handling and mobility. Direct Yaw-moment Control (DYC) is a method of regulating individual wheel torque to control vehicle yaw motion, providing greater stability in cornering. When combined with both a Traction Control System (TCS) and an Anti-lock Braking System (ABS) the tire/road interaction is fully controlled, leading to improved control over vehicle dynamics, whilst also improving vehicle safety.
Technical Paper

Fundamental Parameter Design Issues Which Determine Race Car Performance

There are several fundamental design parameters that determine a race car's performance including mass, centre of gravity height, static load distribution, engine power and aerodynamic forces. A sensitivity analysis is performed on these and other parameters to determine their effect on vehicle performance. This is achieved by looking at specific manoeuvres such as straight line acceleration, braking and steady state cornering to determine the relative effect of the respective parameters. The results presented are determined for both the Leeds University Formula SAE car, figure 1, and a typical mid - late 1990's Formula One car. The results further provide an insight into the differences between high speed cars effected by aerodynamics and low speed cars where aerodynamics makes little or no difference to performance. Combining the performance for a set of manoeuvres provides an insight as to how to improve the overall vehicle lap time.
Technical Paper

Development of a Semi-Active Suspension for a 6×6 Combat Support Vehicle.

In this paper, the development of a full vehicle semi-active suspension controller for a 6×6 CSV (combat support vehicle) is described. The controller uses linear optimal control theory to generate the control gains with the overall aim of reducing ride acceleration and hence maximising cross country speed. A vehicle model is developed to predict ride comfort improvements and, in particular, determine the effect that a roll acceleration weighting factor has on the overall vehicle performance. Subsequently, limited state feedback strategies are evaluated to determine the most effective method of implementation on a real vehicle.