Design of quasi-zero stiffness joint actuator and research on vibration isolation performance

This paper proposes a new QZS joint actuator, which uses a torsion electromagnetic spring (TES) that can generate negative stiffness in parallel with a flexible rod with positive stiffness to obtain QZS characteristics with high static and low motion. In this paper, the expression of TES magnetic moment and stiffness is obtained by static analysis, the simulation is carried out by ANSYS Maxwell finite element software and the effect of TES structure parameters and current on its negative stiffness characteristics is analyzed. Then the dynamic model of QZS joint actuator is established, and the amplitude-frequency response function and torque transmissibility analytical expression are obtained by harmonic balance method, the good vibration isolation performance of QZS joint actuator is revealed. Finally, the stiffness and vibration isolation performance experiments are carried out with the QZS joint actuator to verify the correctness of the theoretical analysis, which indicates that it has a wide range of application background and research significance. •A quasi-zero stiffness joint actuator is proposed toisolate the low frequency torsional vibration.•A torsion electromagnetic spring with an electromagnetic-permanent magnet hybrid structure is proposed.•The negative stiffness characteristic of the torsion electromagnetic spring can be changed by adjusting the coil current.