7
inspection for the UGV and the e-truck in combination
with other variables. Independent of speed, the estimated
distance errors for the UGV moving forward were 1.25 m
(4.10 ft) using RTK and 1.71 m (5.61 ft) using SBAS.
Moving in return travel, NIOSH researchers measured a
distance error of 1.11 m (3.64 ft) using RTK and 1.49 m
(4.89 ft) using SBAS. Independent of speed, the estimated
distance errors for the e-truck moving forward were 0.83 m
(2.72 ft) using RTK or SBAS. Moving in reverse travel, we
measured a distance error of 2.08 m (6.82 ft) using RTK
and 2.03 m (6.66 ft) using SBAS. It seemed that these
results followed the same trend as the results where all vari-
ables are combined. For the UGV, the range in distance
errors were 1.23–1.81 m (4.03– 5.94 ft) moving forward
and 1.06–1.51 m (3.48–4.95 ft) moving in reverse travel.
For the e-truck, the distance error estimates were 0.66–
0.99 m (2.17–3.25 ft) moving forward and 1.92–2.14 m
(6.30–7.02 ft) moving in return travel.
CONCLUSIONS
NIOSH researchers conducted static and dynamic tests to
describe the positional accuracy of GNSS receivers that we
later used as GTIs to assess the detection of CXS intended
for surface mining haul trucks. For static tests, we collected
data from 20 points. We used RTS-based survey equip-
ment to collect data from those same 20 points for com-
parison. We calculated the Euclidian errors for both the
static and dynamic tests. Results of the static tests showed
that positions measured by GNSS receivers match well to
the positions measured by the RTS-based surveying equip-
ment. After conducting the static tests, we conducted the
dynamic tests using a combination of the variables such as
GNSS status, direction of travel, and speed. Among all the
variables, the dynamic test results show that only the GNSS
status and speed affected the estimated errors. Note that we
did not evaluate any CXS.
LIMITATIONS
NIOSH researchers evaluated the accuracy of three GNSS
receivers under a specific set of conditions. We selected the
receiver mounted on the e-truck and the one for the static
tests based on the same brand and model as the ones inte-
grated in the UGV that we used to collect CXS detection
performance data. The performance of the receivers tested
may not be representative of the performance of all GNSS
receivers. In addition, we conducted these tests at a single
location under relatively consistent conditions in which
satellite visibility remained high which is not a typical
Table 3. 95% confidence interval (CI) test results for e-truck
GNSS Status F or R Speed Estimate (m) Lower 95 CI (m) Upper 95 CI (m)
RTK 1.45 1.18 1.73
SBAS 1.43 1.15 1.70
RTK F 0.83 0.55 1.10
RTK R 2.08 1.80 2.35
SBAS F 0.83 0.55 1.10
SBAS R 2.03 1.75 2.30
RTK 10 mph 1.43 1.15 1.71
RTK 15 mph 1.54 1.26 1.81
RTK 5 mph 1.39 1.12 1.67
SBAS 10 mph 1.43 1.16 1.71
SBAS 15 mph 1.56 1.29 1.84
SBAS 5 mph 1.29 1.01 1.56
RTK F 10 mph 0.81 0.53 1.09
RTK F 15 mph 0.97 0.69 1.25
RTK F 5 mph 0.70 0.42 0.97
RTK R 10 mph 2.05 1.77 2.33
RTK R 15 mph 2.1 1.82 2.38
RTK R 5 mph 2.09 1.81 2.37
SBAS F 10 mph 0.83 0.55 1.11
SBAS F 15 mph 0.99 0.71 1.27
SBAS F 5 mph 0.66 0.38 0.94
SBAS R 10 mph 2.03 1.75 2.31
SBAS R 15 mph 2.14 1.86 2.42
SBAS R 5 mph 1.92 1.64 2.2
inspection for the UGV and the e-truck in combination
with other variables. Independent of speed, the estimated
distance errors for the UGV moving forward were 1.25 m
(4.10 ft) using RTK and 1.71 m (5.61 ft) using SBAS.
Moving in return travel, NIOSH researchers measured a
distance error of 1.11 m (3.64 ft) using RTK and 1.49 m
(4.89 ft) using SBAS. Independent of speed, the estimated
distance errors for the e-truck moving forward were 0.83 m
(2.72 ft) using RTK or SBAS. Moving in reverse travel, we
measured a distance error of 2.08 m (6.82 ft) using RTK
and 2.03 m (6.66 ft) using SBAS. It seemed that these
results followed the same trend as the results where all vari-
ables are combined. For the UGV, the range in distance
errors were 1.23–1.81 m (4.03– 5.94 ft) moving forward
and 1.06–1.51 m (3.48–4.95 ft) moving in reverse travel.
For the e-truck, the distance error estimates were 0.66–
0.99 m (2.17–3.25 ft) moving forward and 1.92–2.14 m
(6.30–7.02 ft) moving in return travel.
CONCLUSIONS
NIOSH researchers conducted static and dynamic tests to
describe the positional accuracy of GNSS receivers that we
later used as GTIs to assess the detection of CXS intended
for surface mining haul trucks. For static tests, we collected
data from 20 points. We used RTS-based survey equip-
ment to collect data from those same 20 points for com-
parison. We calculated the Euclidian errors for both the
static and dynamic tests. Results of the static tests showed
that positions measured by GNSS receivers match well to
the positions measured by the RTS-based surveying equip-
ment. After conducting the static tests, we conducted the
dynamic tests using a combination of the variables such as
GNSS status, direction of travel, and speed. Among all the
variables, the dynamic test results show that only the GNSS
status and speed affected the estimated errors. Note that we
did not evaluate any CXS.
LIMITATIONS
NIOSH researchers evaluated the accuracy of three GNSS
receivers under a specific set of conditions. We selected the
receiver mounted on the e-truck and the one for the static
tests based on the same brand and model as the ones inte-
grated in the UGV that we used to collect CXS detection
performance data. The performance of the receivers tested
may not be representative of the performance of all GNSS
receivers. In addition, we conducted these tests at a single
location under relatively consistent conditions in which
satellite visibility remained high which is not a typical
Table 3. 95% confidence interval (CI) test results for e-truck
GNSS Status F or R Speed Estimate (m) Lower 95 CI (m) Upper 95 CI (m)
RTK 1.45 1.18 1.73
SBAS 1.43 1.15 1.70
RTK F 0.83 0.55 1.10
RTK R 2.08 1.80 2.35
SBAS F 0.83 0.55 1.10
SBAS R 2.03 1.75 2.30
RTK 10 mph 1.43 1.15 1.71
RTK 15 mph 1.54 1.26 1.81
RTK 5 mph 1.39 1.12 1.67
SBAS 10 mph 1.43 1.16 1.71
SBAS 15 mph 1.56 1.29 1.84
SBAS 5 mph 1.29 1.01 1.56
RTK F 10 mph 0.81 0.53 1.09
RTK F 15 mph 0.97 0.69 1.25
RTK F 5 mph 0.70 0.42 0.97
RTK R 10 mph 2.05 1.77 2.33
RTK R 15 mph 2.1 1.82 2.38
RTK R 5 mph 2.09 1.81 2.37
SBAS F 10 mph 0.83 0.55 1.11
SBAS F 15 mph 0.99 0.71 1.27
SBAS F 5 mph 0.66 0.38 0.94
SBAS R 10 mph 2.03 1.75 2.31
SBAS R 15 mph 2.14 1.86 2.42
SBAS R 5 mph 1.92 1.64 2.2