3
Dynamic Test Setup for GTI Test Using an Electric
Truck
To evaluate the positional accuracy of the GNSS receiv-
ers while in motion, NIOSH researchers conducted
dynamic tests using two reduced-scale vehicles. We used an
unmanned ground vehicle (UGV) and an electric pick-up
truck (e-truck) as reduced-scale vehicles. The UGV mea-
sured 0.99-m (39-in) long, 0.67-m (26.4-in) wide, and
0.39-m (14.6-in) high, and the e-truck measured about
4.52-m (178-in) long, 1.47-m (58-in) wide, and 1.84-m
(72.25-in) high. Using the manufacturer’s specifications,
each reduced-scale vehicle was equipped with GNSS To
measure the time at which the UGV or e-truck crossed the
reflector, NIOSH researchers used a remote optical laser
sensor (ROLS) pointed at the ground that is capable of
measuring rotation speed from 1–250,000 rpm or pulse per
minute from a reflective tape with an operating range of
0.9 m (36 in). Using the ground facing ROLS, we collected
time-stamped signals triggered by the vehicles crossing over
any of the ten reflectors. Aiming for the center, we drove
each vehicle over each reflector to enable the ROLS to trig-
ger a signal and use that time-stamped signal to select the
position (latitude and longitude) where the signal change
occurred. Because the ROLS and the receivers capable of
producing time-stamped positional data and speed. The
UGV had two pre-installed GNSS receivers located on
opposite corners, on top of the UGV, about 0.39-m (14.6-
in) high from the top surface of the UGV.
We installed one GNSS receiver on the top of the
e-truck about 1.85 m (73 in) from the bumper along its
length, 0.74 m from the driver side along its width, and
1.84-m (72.25- in) high. For the dynamic tests, we col-
lected data from the GNSS and from additional ground
truth devices, such as a wheel tachometer and a remote
optical laser sensor (ROLS), to one central data acquisition
system (DAS).
Dynamic Data Acquisition and Instrumentation
NIOSH researchers used a rugged data recorder or data
acquisition system (DAS), a universal amplifier, and a DAS
software to record and visualize data in real time. The DAS
was mounted on the e-truck or UGV during the test. The
DAQ was capable of recording data from 16 channels. We
used 11 channels. Nine channels were used to record data
for the GNSS receivers such as timestamp, latitude, longi-
tude, altitude, speed, satellite time, satellite date, satellite
status, true heading, etc. We used two channels to record
a voltage output from the wheel tachometer and a ground-
facing optical laser sensor. We set the sampling rate on the
DAQ at 200 Hz, although the sampling rate for the receiv-
ers was limited to 10 Hz.
To measure the speed of the rotating tire of the UGV
or e- truck, we used a laser tachometer. This wheel tachom-
eter could sense the speed of tire rotation up to 30,000 rpm
at a max range of 0.51 m (20 in). Using the wheel tachom-
eter, we collected time-stamped voltage output related
to tire rotations that were later processed into speed. For
that reason, we measured the average circumference of the
tires to extract the radius for both the UGV and e-truck—
prior to the installation of the wheel tachometer. On the
UGV, we installed the wheel tachometer about 50.8 mm
(2 in) from the outside left-front tire. On the UGV tire,
we placed four strips of reflective tape about 90° offset to
trigger a change in voltage output during motion. On the
rear driver side tire of the e-truck, we installed the wheel
tachometer and one strip of reflective tape to trigger the
signal during motion.
GNSS receivers were in different locations on each
vehicle, we measured their vertical and horizontal positions
relative to the 2D area of the vehicles. We designated the
vertical to be the axis along the length of the vehicle and
the horizontal axis along the width of the vehicle. Knowing
these measurements, we calculated the center location of
the ROLS from the center location of the GNSS receivers.
On the UGV, we installed the ROLS with an offset from
the GNSS receivers of 0.7 m (27.44 in) on the vertical axis,
0.27 m (10.69 in) on the horizontal axis, and 0.18 m
(7.25 in) high. On the e-truck, we installed the ROLS
Survey Pole
Reflector
Point 1
Point 2
Middle Point
Figure 2. An illustration of the points on one of the surveyed
reflectors
Dynamic Test Setup for GTI Test Using an Electric
Truck
To evaluate the positional accuracy of the GNSS receiv-
ers while in motion, NIOSH researchers conducted
dynamic tests using two reduced-scale vehicles. We used an
unmanned ground vehicle (UGV) and an electric pick-up
truck (e-truck) as reduced-scale vehicles. The UGV mea-
sured 0.99-m (39-in) long, 0.67-m (26.4-in) wide, and
0.39-m (14.6-in) high, and the e-truck measured about
4.52-m (178-in) long, 1.47-m (58-in) wide, and 1.84-m
(72.25-in) high. Using the manufacturer’s specifications,
each reduced-scale vehicle was equipped with GNSS To
measure the time at which the UGV or e-truck crossed the
reflector, NIOSH researchers used a remote optical laser
sensor (ROLS) pointed at the ground that is capable of
measuring rotation speed from 1–250,000 rpm or pulse per
minute from a reflective tape with an operating range of
0.9 m (36 in). Using the ground facing ROLS, we collected
time-stamped signals triggered by the vehicles crossing over
any of the ten reflectors. Aiming for the center, we drove
each vehicle over each reflector to enable the ROLS to trig-
ger a signal and use that time-stamped signal to select the
position (latitude and longitude) where the signal change
occurred. Because the ROLS and the receivers capable of
producing time-stamped positional data and speed. The
UGV had two pre-installed GNSS receivers located on
opposite corners, on top of the UGV, about 0.39-m (14.6-
in) high from the top surface of the UGV.
We installed one GNSS receiver on the top of the
e-truck about 1.85 m (73 in) from the bumper along its
length, 0.74 m from the driver side along its width, and
1.84-m (72.25- in) high. For the dynamic tests, we col-
lected data from the GNSS and from additional ground
truth devices, such as a wheel tachometer and a remote
optical laser sensor (ROLS), to one central data acquisition
system (DAS).
Dynamic Data Acquisition and Instrumentation
NIOSH researchers used a rugged data recorder or data
acquisition system (DAS), a universal amplifier, and a DAS
software to record and visualize data in real time. The DAS
was mounted on the e-truck or UGV during the test. The
DAQ was capable of recording data from 16 channels. We
used 11 channels. Nine channels were used to record data
for the GNSS receivers such as timestamp, latitude, longi-
tude, altitude, speed, satellite time, satellite date, satellite
status, true heading, etc. We used two channels to record
a voltage output from the wheel tachometer and a ground-
facing optical laser sensor. We set the sampling rate on the
DAQ at 200 Hz, although the sampling rate for the receiv-
ers was limited to 10 Hz.
To measure the speed of the rotating tire of the UGV
or e- truck, we used a laser tachometer. This wheel tachom-
eter could sense the speed of tire rotation up to 30,000 rpm
at a max range of 0.51 m (20 in). Using the wheel tachom-
eter, we collected time-stamped voltage output related
to tire rotations that were later processed into speed. For
that reason, we measured the average circumference of the
tires to extract the radius for both the UGV and e-truck—
prior to the installation of the wheel tachometer. On the
UGV, we installed the wheel tachometer about 50.8 mm
(2 in) from the outside left-front tire. On the UGV tire,
we placed four strips of reflective tape about 90° offset to
trigger a change in voltage output during motion. On the
rear driver side tire of the e-truck, we installed the wheel
tachometer and one strip of reflective tape to trigger the
signal during motion.
GNSS receivers were in different locations on each
vehicle, we measured their vertical and horizontal positions
relative to the 2D area of the vehicles. We designated the
vertical to be the axis along the length of the vehicle and
the horizontal axis along the width of the vehicle. Knowing
these measurements, we calculated the center location of
the ROLS from the center location of the GNSS receivers.
On the UGV, we installed the ROLS with an offset from
the GNSS receivers of 0.7 m (27.44 in) on the vertical axis,
0.27 m (10.69 in) on the horizontal axis, and 0.18 m
(7.25 in) high. On the e-truck, we installed the ROLS
Survey Pole
Reflector
Point 1
Point 2
Middle Point
Figure 2. An illustration of the points on one of the surveyed
reflectors