Abstract
Keywords - Vehicle dynamics, Modelling and simulation, Real-time simulation, Tire property, Hardware-In-the-Loop Simulator
Abstract - Tire Hardware-In-the-Loop Simulator, abbreviated as Tire HILS in this paper, was developed on the concept of using real experiment tire as a part to generate forces and moment as inputs for a simulated vehicle model for study on handling and stability of vehicle based on a 2-DOF-vehicle model, so called a bicycle model. The key point of the tire HILS is that the computer simulation and experimental work is carried out together in the same time as a real time simulation technique. From our past works (1)-(2), it was found that the tire HILS has a great advantage when tire characteristics reach to a non-linear region. Even when considering tire characteristics only in lateral motion of vehicle, non-linear properties of tire can be reached at large tire sideslip angle, usually larger than 3 degrees based on racing kart tire. Moreover, in a real driving condition, non-linear properties of tire can be easily reached by applying a brake, which causes changing in slip ratio and load of tire. Therefore, to make the tire HILS to be more useful in study handling and stability, vehicle longitudinal motion by applying a brake is considered in this paper. Therefore, when consider longitudinal motion of vehicle, vehicle model will be 3-DOF model, which has three independent variables.
Tire characteristics, which related to friction coefficient versus slip ratio, can be studied by installing hardware brakes for small-sized car to each axle of the tire HILS. From this new feature of hardware brake, the experiment of vehicle longitudinal motion such as braking without cornering or braking during cornering can be carried out. To simulate longitudinal vehicle motion, the drum is considered as a road surface. Therefore, the longitudinal speed of vehicle can be simulated with the rotation of the drum. And by monitoring the rotating speed of drum and both front and rear tires, the real-time slip ratio of both tires can be investigated. Load transfer from the rear to front tires during braking is also considered in this paper.
Results from the tire HILS show that braking motion causes a significant change in properties of both front and rear tires especially during cornering which affects to lateral motion of vehicle. It was found that the dynamic response of the tire HILS during a braking maneuver at cornering, tack-in, is reasonable and well simulated comparing with off-line computer simulation. It is concluded that vehicle handling and stability during a braking maneuver can be analysed effectively by using the Tire HILS. That means Tire HILS has a possibility to be used as a tool to study vehicle dynamics considering both in lateral and longitudinal motion.