The use of computer assisted systems is a major step towards improving the safety and performance of vehicles. This paper investigates one aspect of system design, the braking system. The design exercise is based upon a simulation of a cars braking system enables several alternative control strategies to be assessed. The findings illustrate the problems involved and the opportunities available for the application of an ‘intelligent’ control strategy.
The recent developments in the new generation of sensor rich, distributed autonomous control technology has had a profound effect on the design of modern automotive vehicles. In particular, the intelligence afforded by robust embedded microelectronics throughout the vehicle together with the communications network typologies have resulted in control systems which greatly enhance the vehicle performance covering aspects such as safety, passenger comfort and environmental impact, to name but a few. In addition, an improved understanding of vehicle performance can be gained from the development of software simulation techniques which employ a range of system dynamic models, with the aim of achieving improved vehicle control strategies.
The following paper, investigates the performance of existing and potential strategies applicable to vehicle automatic braking system’s, known as ABS. A system model developed using the MATLAB simulation environment is described, which is then implemented with a 'Bang-Bang' controller strategy to provide a benchmark for the evaluation of alternative control strategies. The main alternatives investigated were centred around PI and Fuzzy Logic based systems which take advantage of information received from the distributed sensors. One of the main aims was to improve the driver comfort when the ABS is activated whilst maintaining optimal system performance in terms of minimising the vehicle stopping distance under emergency conditions. It is well known that the existing Bang-Bang control implementation is very severe in terms of the physical shock the driver experiences through brake pedal pulsations, when the system is activated.
The following sections evaluate possible alternatives and provide an indication of the level of system performance which could be achieved. The advantages of such intelligent control are that they can take full advantage of developments in Smart Tyre technology together with the increasing integrity of micro technology.
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