Detection of the Bolt Loosening Angle through Semantic Key Point Extraction Detection by Using an Hourglass Network

Table 3

Absolute values and errors of the bolt loosening angles obtained using the proposed method and the method of Zhao [10] under the same rotation angle.

Test sample	Calculated value (°)	Actual value (°)	Difference value (°)	Error (%)
Zhao [10] a	6.33	10	3.67	36.7
Zhao [10] b	16.2	20	3.8	19
Zhao [10] c	23.05	30	6.95	23.2
a	9.54	10	0.46	4.6
b	19.72	20	0.28	1.4
c	29.9	30	0.1	0.33