A novel ring-beam traveling-wave piezoelectric actuator for joint drive systems: development, vibration analysis, and experimental characterization

Joint piezoelectric actuators are widely used in joint drive systems such as robots due to their high precision, self-locking upon power loss, and compact structure. However, conventional standing-wave joint piezoelectric actuators often suffer from unstable driving performance and an inability to achieve bidirectional motion. Traveling-wave types, meanwhile, typically rely on auxiliary components that hinder miniaturization and system integration. To address these challenges, a novel ring-beam structure traveling-wave driven joint piezoelectric actuator is proposed. Firstly, the operating principle was revealed through theoretical modeling and validated using finite element analysis, which also facilitated the determination of optimal stator dimensions. Subsequently, the vibration characteristics of the stator are tested to identify its optimal operating frequency. Finally, the performance of the actuator is evaluated. Performance tests demonstrated that, under an excitation voltage of 300 Vp-p at 33.75 kHz, the actuator achieved a maximum rotational speed of 117 rpm and a stall torque of 7.15 mN m with a resolution of 28.89″ in the forward direction; the corresponding values in reverse were 104 rpm, 7.13 mN m, and 16.39″. These results confirm the correctness of the proposed design and its driving principle, providing a new approach for the miniaturization and integration of joint piezoelectric actuators.