Table 2.

The features used for the detection of collisions.

Features	Function Equation
Geometric Appearance	$q_{M2},q_{M3}$
vibration Frequencies	${\widehat{\omega }}_{Di}(i=1,2,\cdots ,m)$
vibration modal	${\widehat{\varphi }}_{kji}(k=1,2,\cdots ,l;j=1,2,\cdots ,n;i=1,2,\cdots ,m)$