Normalized Coupling Method for Speed Synchronization of Multi-Axis Driving Vehicles

Abstract

A new normalized coupling synchronization (NCS) method is proposed to solve the problem of synchronizing the speeds of all wheels in a multi-axis independent driving system without mechanical transmission connection. The NCS method integrates normalizing and coupling techniques by emulating mechanical line shaft. All wheelsʹ speeds are normalized, and thus can be synchronized whether the wheelʹs revolution speeds are the same or different. Then, all of the normalized wheel speeds are coupled in order to eliminate speed synchronization errors between any pair of axes. Therefore, the new algorithm is able to achieve global speed synchronization. It is applicable to multiaxis driving vehicles either driving in straight line or making a turn. The conducted computational simulation shows that the proposed method gets better result in reducing speed synchronization errors in both cases of same and different wheel speeds compared to some classic speed sync methods in the literature. To further validate the effectiveness and applicability of the NCS method, it is also applied to a four-wheel-driving and four-wheel-steering vehicle for comparison tests. The onboard tests indicate that the proposed method achieves a fast convergence of speed error.