Analysis of the control strategy for double-skyhook semi-active suspension based on fractional-order calculus

As a classical control model, the double-skyhook control algorithm that combines a skyhook inerter and a skyhook damper can adapt to changes in both road and load conditions. However, it regulates the control force only by adjusting the damping and inertance coefficients, without involving phase adjustment, which limits its control effectiveness. To address this limitation, fractional-order calculus is introduced into the double-skyhook control algorithm. By replacing the integer-order displacement differential terms in the original control law with fractional-order differentiation, the proposed fractional-order double-skyhook control algorithm enables continuous adjustment of both the magnitude and phase of the control force. A fractional-order double-skyhook semi-active suspension system is then constructed to achieve precise regulation of the actuator output force. The fractional-order parameters, including both coefficients and orders, are optimized via a genetic algorithm under varying loads and road conditions to ensure optimal control performance. Simulation results and Hardware-in-the-loop (HiL) simulation results demonstrate that the introduction of fractional-order calculus effectively enhances the control performance of double-skyhook semi-active suspensions.