A Technical Research on Parameters Acquisition of Automotive Four-wheel Alignment

Four-wheel alignment parameters are important indexes to promise handling stability when automobile drives in straight line. Aiming at the problems of traditional four-wheel alignment measurement - kingpin inclination angle and kingpin caster angle are calculated indirectly and approximately by geometrical relationship, which cannot be measured directly or have large measurement error, etc. This paper proposes a new technique to obtain the four-wheel alignment parameters by means of installing an intelligent triple-axis acceleration sensor unit on the wheel to make inertia measurement on wheel alignment angle so as to establish a brand new four-wheel alignment attitude parameter calculation model to acquire four-wheel alignment parameters. The new technique proposed here can establish a four-wheel alignment parameters calculation model to acquire the parameters through installing an intelligent triple-axis acceleration sensor unit on the wheel. The experiment results indicate that under experimental conditions, the indication error of wheel alignment parameter (γwi, αwi, γki, θki) is (-0.01°, 0.00°, -0.65°, -0.31°), and the indication variance is (0.45°, 0.63°, 1.00°, 0.49°). This new technique is able to test the four-wheel alignment parameters quickly, dynamically and accurately, achieve a better measurement accuracy on performance index, and realize expected effect.