**Table 2.**

*FTA event definition of worm vibration.*

Taking the worm rotation meta-action (shown in **Figure 10**) and the end-toothed disc indexing table (shown in **Figure 11**) as examples, the MU-FTA and MU-FMEA are shown below [24]. Therefore, MU-FTA and MU-FMEA are shown in **Figure 12** and **Table 3**, and the specific contents of the fault tree are shown in **Table 2**.
