A novel calibration method and platform for automobile wheel alignment system based on spherical kinetic pair

The research of calibration model for the wheel alignment system is a crucial area for automobile safety. For the disability of calibrating measurement results of wheel alignment system, the theoretical errors based on the superposition principle are analyzed. Simulation results show that the errors are more than 0.4deg whereas the common precision of wheel alignment system is 0.02deg. Novel calibration model for caster and steering axle inclination (SAI) is presented according to independent generation principle in vertical plane and transverse plane of automobile. Method of calibration platform based on spherical kinetic pair is introduced, which achieves higher accuracy. The experimental results show that linear errors exist in the measurement of SAI and caster. The error of SAI is over 10´ when caster is over 15deg and system errors increase as the projective angles increase.