Research on rotary magnetorheological damper with dual-mode for hydraulic robotic legs

• A rotary MR damper combining squeeze and valve modes was developed for heavy-duty robots • A damping force model was established to characterize the dual-mode operation • The damper achieves a maximum output torque of 314.02 N·m in experiments • Equipped with the damper, a hydraulic robotic leg reduces vibration amplitude by 84.9% • The damper also cuts vibration settling time by 69.2%, improving robotic leg performance Magnetorheological (MR) dampers often face challenges with large structures and insufficient damping, limiting their applicability in hydraulic robots with high force-to-weight ratios. To address these limitations, this research introduces a novel dual-mode rotary MR damper, combining a compact structure with enhanced damping performance. A comprehensive mechanical model is developed to describe the torque response of the damper under rotational excitation, providing a foundation for dynamic analysis and control integration in robotic applications. Additionally, a detailed magnetic field simulation is conducted to examine the spatial magnetic flux distribution within the dual-mode structure. The results demonstrate that the magnetic flux path is well-defined, and the magnetic flux density in key regions meets design requirements. Experimental validation is carried out to assess the damper's performance, showing that under 2.5 A current, the damper generates a maximum torque of 314.02 N·m, significantly exceeding the design requirement of 252 N·m. Furthermore, vibration attenuation experiments reveal a substantial improvement in performance, with a reduction in amplitude by 84.9% and settling time by 69.2%, indicating excellent damping effectiveness. This work offers a comprehensive solution to vibration control in hydraulic robots, particularly those requiring high force-to-weight ratios, and demonstrates the potential of the proposed dual-mode rotary MR damper.