A new fail-safe active seat suspension system using magnetorheological technology for enhanced comfort and safety

• A new fail-safe active seat suspension to improve safety is proposed. • Using magnetorheological fluid to improve the frequency of active force commutation. • Different control modes between bevel gears change the seat control mode. • The fail-safe mechanism is activated when the seat suspension active system fails. • A larger current enables the actuator to generate greater control force. Active seat suspensions have emerged as a widely adopted solution to address the growing demand for enhanced ride safety and comfort. However, current active seat suspension systems are significantly hindered by their inability to guarantee driver safety in the event of system failures, as well as delays in the change of active force direction, which ultimately compromise the vibration reduction performance. To address these challenges, this paper develops an innovative active seat suspension system based on magnetorheological (MR) technology. The core component of this new system is an MR joint which enables the new active seat suspension to possess fail-safe characteristic that ensures driver safety in the event of an active system failure, and facilitates the system with high-frequency active force commutation without altering the rotation direction of the motor, allowing the MR joint to more quickly follow the controller’s output and thereby enhancing vibration reduction performance. The performance of the novel seat suspension was evaluated experimentally in both fail-safe mode and active vibration reduction mode, focusing on vibration attenuation and suspension travel reduction. The test results indicate that the proposed active seat suspension achieves a 36.9% vibration reduction under fail-safe mode with a sky-hook controller and 52.9% vibration reduction with an H ∞ controller when comparing to the uncontrolled suspension. Even comparing to some reported active seat suspension, these experimental data still demonstrate obvious superiority in vibration reduction. Therefore, this innovative active seat suspension with MR joint has been verified that it cannot only guarantee driver safety but also significantly enhance driver comfort, overcoming the key shortcomings faced by the existing active seat suspension systems.