Stair Climbing Control for 4-DOF Tracked Vehicle Based on Internal Sensors

Table 2

Relationship between motion phases and failure modes.

Motion phases (MP)		Failure modes (FM)
		I slipping	II falling backward	III direction error	IV excessive shock
Ascend	(i) Entering	Easy to occur and critical	Hard to occur		Does not happen if the slipping is prevented
	(ii) Normal climbing	(i) Hard to occur; (ii) Not critical; because of grousers (=Assumption)	Easy to occur and critical		(i) Hard to occur; (ii) Not critical
	(iii) Leaving		Hard to occur if it was prevented in normal climbing		Easy to occur and critical
Descend	(i) Ready	Hard to occur
	(ii) Entering	Hard to occur	Easy to occur and critical	Hard to occur	Easy to occur and critical
	(iii) Normal climbing	(i) Hard to occur; (ii) Not critical; because of grousers	Easy to occur and critical		(i) Hard to occur; (ii) Not critical
	(iv) Leaving	(i) Easy to occur; (ii) Not critical; except for excessive shock	Hard to occur if it was prevented in normal climbing		Easy to occur and critical