VEHICLE DYNAMICS STUDY BASED ON GPS DEVICES Ion PREDA*, Dinu COVACIU†, Gheorghe CIOLAN‡ Abstract: The GPS technology is more and more widespread between common users, mainly for navigation applications, but to date the GPS devices performances become good enough to be used as tools in research activities. The price and easiness of use make this type of devices extremely interesting for the experimental study of any vehicle type dynamics. This paper shows some possibilities to process GPS data, allowing obtaining useful information about the vehicle dynamics behaviour. Also are presented and compared the data obtained from various GPS devices. The authors realised a computer program that run in AutoCAD environment, taking benefits from its graphical and list processing features. The data can be imported from different GPS devices using standard or proprietary file formats. Based on position and time information, it can be ascertained the speed, acceleration or slope and can be estimated the moving resistance forces and the power delivered by the engine. These results were represented as plots in different ways, for easy interpretation. Keywords: vehicle dynamics, GPS, data acquisition and processing, CAD programming 1. INTRODUCTION In the last years, the GPS technology became common and popular. On the market are offered various applications, especially for navigation and for recording of the route travelled by different vehicles (aircraft, ships, cars) or pedestrians (on city or on mountain trails). Combining position information obtained from GPS with detailed digital maps, it can find the desired destinations and the optimum routes to follow. The diminishment of electronic-devices price and the precision offered by the GPS, even for commercial applications, encourage the apparition of more and more new applications. This paper presents possibilities to use GPS devices, designed and experinced by the authors to assess, by measuring and estimating, the dynamic behaviour of vehicles. Some results of the performed tests are also presented. 2. GPS DEVICES USED FOR THE STUDY For the vehicle dynamics study were used four different GPS devices with tracking possibilities, presented in figure 1: