## 3 Novel Rotating Motion Mechanism
### Linear Motion to a Rotational Motion Mechanism
#### 3.2.5 Screw Gear Ratchet Combination Mechanism  
[PERSON] et al. [119] proposed a bidirectional energy harvesting floor with a slow-release regulation mechanism. The working principle of this mechanism is shown in Figure 58 [119]. When pedestrians step on the floor, the torsion bar moves downward, driving the driven gear to rotate counterclockwise. Through the gear set, the speed increases, and the direction changes, causing the ratchet wheel I to drive the ratchet wheel to rotate counterclockwise. After the pedestrian leaves, the reset spring pushes the torsion bar to reset, driving the driven gear to rotate clockwise. The gear set accelerates again, causing the ratchet wheel II to drive the ratchet wheel counterclockwise. Ratchet discs I and II are driven unidirectionally by the pawl, ensuring that the ratchet constantly rotates at high speed in one direction regardless of whether it is stepped on or reset. Figure 57: Rack mechanism of serial coupling (Arrows indicate the direction of motion). Figure 56: WEC platform with MLS in PTO cylinder (Arrows indicate the direction of motion). Table 12 summarizes and compares the transmission performance of the above different mechanisms for converting linear motion into rotational motion. The research on linear to rotational motion transmission mechanisms presents a trend of coordinated development of multiple technological paths, achieving significant breakthroughs in precision, efficiency, and environmental adaptability. The traditional ball screw mechanism achieves a triple load increase through planetary structure innovation, while the static pressure screw achieves submicron precision through differential synchronous drive but is limited by high cost and low load characteristics; The EHSA system based on the slider-crank pawl mechanism improves the vibration energy conversion efficiency to 67.75% through a bidirectional rectification mechanism, but its material fatigue problem urgently needs to be solved by new composite materials. The new reverse magnetic pole maglev system adopts a polarised magnetic circuit design to achieve zero-friction transmission in wave energy conversion. Still, the dependence on low temperature superconductivity leads to a significant increase in system complexity. The series-coupled rack mechanism achieves displacement direction-independent continuous output through the innovation of one-way bearings, and its mechanical conversion efficiency of 64.31% shows potential in the field of track vibration recovery. However, the bottleneck of power density needs to be overcome through topology optimisation. The high-frequency energy harvesting \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Types** & **Advantages** & **Disadvantages** & **Applications** \\ \hline Planetary ball screw [114] & 3 times the load & High-cost & Stamping equipment \\ Static pressure screw [115] & High precision, up to sub-micron level & Low load & Heavy-duty precision \\  & The conversion efficiency & High cost & machinery \\ Slider crank ratchet & of vibration recycling & There is a material & Train shock absorption \\ mechanism [116] & Machinery can reach & fatigue issue & Train shock absorption \\  & 67.75\% & & \\ Magnetic guide screw [117] & zero friction & Difficult to Maintain & Wave Power \\ Coupling rack mechanism [118] & Flywheel stabilisation, the mechanical conversion & Difficulty in maintenance & Generation \\  & Efficiency can reach 64.31\% & and limited power & Track vibration \\ Screw gear ratchet & High-frequency & & Energy recovery in densely \\ combination mechanism & conversion, high energy & Easy to wear and tear & Depulated \\
[119] & harvesting efficiency & & areas \\ \hline \hline \end{tabular}
\end{table} 
Table 12: Comparison of linear motion conversion to rotary motion mechanisms. Figure 58: Working process of mechanical transmission (Arrows indicate the direction of motion). characteristics of the helical gear ratchet combination mechanism are outstanding in energy recovery in densely populated areas.