Wireguide driving actuator using resonant-type smooth impact drive mechanism

• A wireguide was attached at the tip of Langevin type transducer.
• Remote actuation at the tip of wireguide using R-SIDM is proposed.
• A quasi-saw-shaped displacement is excited by combining two sinusoidal waves.
• The resonance frequency ratio of transducer and wireguide were designed to be 1:2.
• A driving speed (176 mm/s) and a maximum thrust (0.47 N) were measured.

This paper proposes a wireguide-driving piezoelectric actuator for narrow space driving such as in endoscopic devices. Conventional wireguide-driving actuators use torsional or bending vibration. We examined a resonant-type smooth impact drive mechanism (R-SIDM) utilizing longitudinal vibration as the driving principle. The longitudinal vibration is resistant to outside disturbances. Different to conventional smooth impact drive mechanism (SIDM) actuators, R-SIDM actuators use the resonant effect. The quasi-saw-shaped displacement is excited by combining two resonant vibrations with a frequency ratio of 1:2. This driving principle allows lower input voltage compared to that of the conventional SIDM. As the driving source, a step-shaped Langevin transducer was fabricated. With this step-shaped design, the longitudinal resonant frequency ratio f3/f1 could be adjusted to 2. At the tip of this transducer, an aluminum wireguide was attached to excite a quasi-saw-shaped vibration at the end tip. The length of the wireguide was designed to match the resonant frequencies of the transducer. It was confirmed that a bearing rotor (diameter: 10 mm) could be rotated. As we expected, a quasi-saw-shaped vibration was excited, and we could measure a non-loaded driving speed of 176 mm/s and a maximum load of 0.47 N for a 100 Vp–p input voltage and a 6.0 N preload.