A Wideband Torque Control Method for Transmission System Based on Mixed Negative‐Imaginary and Finite‐Gain Method

Broadening the control bandwidth is essential for improving the performance of transmission systems, but this is often limited by mechanical vibrations in the system. A novel wideband torque control method with a dual‐loop structure is proposed for bandwidth expansion and vibration suppression by exploiting negative imaginary system theory. Due to out‐of‐phase distribution and partial negative imaginary properties of the resonant modes, a robust stability analysis framework for feedback interconnections of linear time‐invariant mixed negative imaginary and finite gain systems is developed. Positive position feedback controllers are then designed in the damping loop to perform a phase shaping on the nominal system leading to an outstanding improvement in damping. An integral tracking controller is incorporated to ensure steady‐state accuracy in the outer‐loop, which can be independently designed focusing solely on stability, control bandwidth and transient performance. Simulation comparisons are conducted to verify the effectiveness and superiority of the proposed method in terms of vibration suppression and tracking performance. The achieved bandwidth exceeds the primary resonant frequency, demonstrating a competitive result among existing damping control methods.