Active Suspension Modelling and LQR Controller Design for a High-Speed Train Under Continuous Road Disturbance and Parameter Uncertainty

Mehmet KARAHAN

Abstract

High-speed trains provide a faster and much cheaper transport in comparison with air transport for distances shorter than 640 km. Also, in contrast with road transport, they feature a much lower accident rate and a higher passenger and freight capacity, they are more durable, take up less space, and produce fewer carbon emissions. Therefore, high-speed trains are an attractive transportation option. However, as high-speed trains travel at speeds of at least 200 km/h, even a small bump on the railway track can cause significant vibrations which can lead to wheel slippage, jeopardizing the passenger comfort and safety. Therefore, high-speed trains require an advanced suspension system. This paper proposes an active suspension system with an LQR controller for a high-speed train. The designed suspension system was tested under continuous road disturbance and parameter uncertainty and a comparative robustness analysis was conducted involving a conventional passive suspension system. Simulations related to the actuator force, sprung mass acceleration, suspension travel, wheel deflection, and body displacements were performed for both suspension systems. In this context, the time responses for both suspension systems were obtained and compared. The analysis revealed that the LQR-controlled active suspension achieved a shorter rise time and settling time and featured lower oscillations. This demonstrates that the proposed system provides passengers with a more comfortable and safer journey.

Keywords

Active suspension, Passive suspension, LQR control, Full-state feedback, High-speed train, Disturbance, Robustness, Ride comfort.

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