## 3 Novel Rotating Motion Mechanism
### Rotary Actuator
#### 3.6.5 Rotary Piezoelectric Stick-Slip Actuators
At the same time, the piezoelectric stick-slip rotary actuator (Table 17) represents progress in the field of precision micro drives, which achieves stepwise rotation through the inverse piezoelectric effect of piezoelectric elements. The ultra compact and high speed piezoelectric tube spiral electrode type is suitable for micro optical focusing; The double piezoelectric tube inertia type with large step size and fast response is ideal \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Types** & **Advantages** & **Disadvantages** & **Applications** \\ \hline Piezoelectric tube & Ultra compact, high angular & High driving voltage (high & Micro-optical \\ spiral electrode type & velocity, silicon carbide-coated steel & dielectric loss of PZT-5A), poor & focusing system \\  & shaft reduces wear rate. & low temperature performance & \\  & Large step angle (reduced adhesion & Large volume (up 120\% & \\ Double piezoelectric & of alumina ceramic shaft), fast & compared to traditional design), & Precision rotating \\ tube inertia type & response (0.1 ms), low threshold & weak axial load (\(<\)10 N, limited & \\  & voltage (less than 50 V) & preload force of beryllium & platform \\  & Inhibit rollback (stable friction with & bronze spring) & \\  & silicon carbide coating), high speed & Complex structure (requiring & \\ Dual-mode & (elastic amplification strain of & dual PZT-4 stack), humidity & \\ incentive type & titanium alloy hinge 1.8 times), & sensitive (fluctuation of silicon & \\  & high temperature resistance & carbide friction coefficient greater & \\  & & thin 20\% when greater than 80\%) & \\  & Anti-impact (hard alloy driven & Low rotational speed (0.85 rad/s, \\  & foot), low power consumption (less & insufficient damping of & \\  & than 5 W, beryllium bronze hinge & aluminium alloy substrate), & Field robot joints \\ flexible hinge type & with low hysteresis loss), & demanding machining accuracy & \\  & bidirectional consistency greater & (\(\pm\)1 \(\mu\)m) & \\  & High torque (12 mN \(\cdot\) m), smooth & Extremely high cost, high & \\  & motion (microstructured copper & humidity failure (copper alloy & \\  & rotating type & alloy oil storage reduces viscosity & \\  & and slip mutation), & texture blockage above & \\  & radiation resistance & 80\% humidity) & \\ \hline \hline \end{tabular}
\end{table} 
Table 17: Comparison table of classification of rotary piezoelectric visco sliding actuators [141]. for precision turntables; Dual mode incentive type anti rollback and high temperature resistance meet the requirements of aerospace orientation; Umbrella shaped flexible hinge type for impact resistance and low power adaptation of field robot joints; The high torque and radiation resistance characteristics of the biomimetic snake-like rotating type are aimed at special biomimetic applications. However, piezoelectric stick-slip actuators face high driving voltage, humidity sensitivity, extreme machining accuracy requirements, or high cost. Overall, these actuators have made breakthroughs in high-efficiency compact driving, low power precise positioning, biomimetic safe interaction, efficient adjustable stiffness, and precision micro-nano driving, jointly promoting the development of rotary actuation technology towards high performance, intelligence, and scene adaptability.