A control algorithm for lateral semi-active suspension based on sliding mode observer is proposed to solve lateral vibration of high-speed trains caused by railway surface excitation. Firstly, the multi-degree-of-freedom vehicle dynamics model of high-speed train is revised on the basis of variation in spring coefficient caused by long-time vibration in practical engineering; Secondly, the observer based on sliding mode variable structure is designed to obtain real-time estimation of unknown interference terms using the equivalent control principle of sliding mode variable structure, which can be further used to calculate the observed values of unknown interference terms; Finally, a control algorithm based on sliding mode observer is proposed. The algorithm inputs complex unknown interference observed values into the sliding mode controller (SMC) as feedback, thereby allowing the observed values to accurately track nonlinear unknown disturbance and weaken the vibration. Stimulation and experimental verification have proven the effectiveness and feasibility of the proposed method.

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