Machine Vision Based Automatic Detection Method of Indicating Values of a Pointer Gauge

Table 4

Comparisons between manual reading and visual detection.

The pressure output of the checkpoint (MPa)	The indicating value of visual detection				The indicating value of manual reading				Comparison (error 1 − error 2)
	Positive stroke		Error 1: (MPa)	Relative error 1: (%)	Positive stroke		Error 2: (MPa)	Relative error 2: (%)
	Standard gauge: (MPa)	Tested gauge: (MPa)			Standard gauge: (MPa)	Tested gauge: (MPa)
0	0	0	0	0	0	0	0	0	0
0.025	0.024343	0.025650	0.001310	5.37000	0.024	0.026	0.002	8.333	0.08202
0.050	0.048727	0.050200	0.001473	3.02296	0.049	0.051	0.002	4.082	0.03533
0.075	0.074387	0.075470	0.001080	1.45644	0.075	0.076	0.001	1.333	0.01225
0.100	0.100408	0.100100	0.000308	0.30675	0.099	0.101	0.002	2.02	0.02051
0.125	0.125060	0.126000	0.000940	0.75164	0.125	0.126	0.001	0.8	0.00706
0.150	0.149762	0.150900	0.001140	0.75987	0.15	0.152	0.002	1.333	0.01219
0.175	0.174613	0.177626	0.003010	1.72553	0.175	0.173	0.002	1.1429	0.01440
0.200	0.198316	0.202263	0.003950	1.99026	0.2	0.203	0.003	1.5	0.01105
0.225	0.225053	0.226146	0.001090	0.48566	0.224	0.227	0.003	1.339	0.01230
0.250	0.249344	0.249057	0.000287	0.11510	0.249	0.252	0.003	1.205	0.01233