Digital image correlation techniques for measuring tyre-road interface parameters : Part 1 - Side-slip angle measurement on rough terrain

摘要

This paper presents inexpensive methods whereby the vehicle side-slip angle can be measured accurately at low speeds on any terrainusing cameras. Most commercial side-slip angle sensor systems and estimation techniques rely on smooth terrain and high vehicle speeds,typically above 20 km/h, to provide accurate measurements. However, during certain in-situ tyre and vehicle testing on off-road conditions,the vehicle may be travelling at speeds slower than required for current sensors and estimation techniques to provide sufficientlyaccurate results. Terramechanics tests are typical case in point. Three algorithms capable of determining the side-slip angle from overlappingimages are presented. The first is a simple fast planar method. The second is a more complex algorithm which can extract notonly the side-slip angle but also its rotational velocities and scaled translational velocities. The last uses a calibrated stereo-rig to obtainall rotations and translational movement in world coordinates. The last two methods are aimed more at rough terrain applications,where the terrain induces motion components other than typical predominant yaw-plane motion. The study however found no discernibledifference in measured side-slip angle of the methods. The system allows for accurate measurement at low and higher speedsdepending on camera speed and lighting.