Design and Optimization of Hardware-Efficient Filters for Active Safety Algorithms

In this paper we present an example design process of filters used in automotive industry. Signal preprocessing is very important operation in active safety algorithms. Such algorithms usually take into account the vehicle state that includes position, velocities and accelerations of the car. On the basis of these data, as well as the parameters and trajectories of external objects "observed" by the car, the algorithms make decisions about various safety actions. Designer of such algorithms must assure an appropriate quality of such signals, which usually means a proper filtering. In this paper we focus on selected important aspects of the filter design process. The main objectives of the presented investigations is to obtain such filters that ensure a sufficient rejection of undesired components from the signal and at the same time that do not introduce too high delay to the processed signals. In our work we consider linear filters such as finite impulse response (FIR) and infinite impulse response (IIR) filters of different types and lengths, as well as nonlinear filters - in this case median filters. Selection of these filters results from the parameters of the signal. Since the filters have to be finally implemented in low cost and low power devices, in the paper we focus also on hardware implementation issues. Selected filters have been implemented in Field Programmable Gate Array to verify the concept.