4. TEST ROAD PROFILES 4.1 Discrete Obstacles The discrete obstacles are representative of defects such as potholes, bumps and stones. The trapezoidal bump is considered due to its popularity in vehicle model validation tests (Letherwood and Gunter, [12]). Two different trapezoidal bumps are placed along the tracks in two different configurations to construct two different test road surfaces having discrete obstacles. Fig. 2 shows a picture of the trapezoidal bump in frame (a) [5] with diagrams of the two different bumps in frames (b) and (c) at the bottom. Fig. 2 Trapezoidal bumps as discrete obstacles (a) in picture (b) larger 150 mm hump (c) smaller 100 mm hump. The two trapezoidal bumps are arranged on the road in two different layouts as shown in Fig. 3. The layout in (a) comprise the larger and smaller bumps symmetrically placed 10.4 m away from each other on either side of the track. Thus both tires on the front axle are expected to climb over the bump at the same time assuming that no wheel steered off ahead of another, as is normally done by drivers, to minimize the effects of severe pitching. In so doing roll effects are kept to a minimum while maximizing pitching effects on the vehicle body due to superposition of resultant vibrations on the vehicle body. The 349
RkJQdWJsaXNoZXIy MTMzNzEzMQ==