3
battery. Although the battery is warranted for one year, the expected battery life
should be several years. Replacement batteries are available from Vernier (order
code: GDX-BAT-300).
Storage and Maintenance
To store Go Direct Acceleration for extended periods of time, put the device in
sleep mode by holding the button down for at least three seconds. The red LED
will stop flashing to show that the unit is in sleep mode. Over several months,
the battery will discharge but will not be damaged. After such storage, charge
the device for a few hours, and the unit will be ready to go.
Exposing the battery to temperatures over 35°C (95°F) will reduce its lifespan. If
possible, store the device in an area that is not exposed to temperature extremes.
Water Resistance
Go Direct Acceleration is not water resistant and should never be immersed in
water.
If water gets into the device, immediately power the unit down (press and hold
the power button for more than three seconds). Disconnect the sensor and
charging cable, and remove the battery. Allow the device to dry thoroughly
before attempting to use the device again. Do not attempt to dry using an
external heat source.
How the Sensor Works
Accelerometer
The accelerometers are microelectromechanical devices (MEMS devices) each
consisting of a cantilever and a test mass. As the mass is accelerated, the
cantilever bends, generating a signal proportional to the acceleration. Three
orthogonal axes provide three channels of acceleration information for most
experiments and an additional three channels of acceleration for high-
g
situations are also available. Acceleration measurements are used for the angle
measurement.
Gyroscope
The gyroscope is a microelectromechanical device that uses a vibrating structure
to determine rate of rotation using the Coriolis force on the structure. Three
orthogonal axes provide three different channels of rotation information.
Altitude
The altimeter is a temperature-compensated, absolute air pressure sensor that can
measure from 260 mBar up to 1260 mBar. We use the following equation to
convert to altitude in meters:
assuming that
p
0
, the pressure at sea level, is 1013.25 mBar. The resulting
altitude range is from about –1800 m to 10000 m.
experiment is created in the software. Calibration writes an offset value to the
sensor, as opposed to setting a zero temporarily for the duration of an
experiment. The offset value will then be applied each subsequent time the
sensor is used. To calibrate the sensor, click or tap the meter for the axis you
wish to offset and choose Calibrate. Orient your sensor as for measurement and
enter 0 m/s
2
(or whatever offset you choose, for example –19.6 m/s
2
if you
orient an axis vertically downward instead of upward). Click or tap Keep, then
Apply the calibration.
Gyroscope
This sensor is factory calibrated.
Altitude
This sensor is factory calibrated, but you can choose to offset the value based on
your physical location using the calibrate option.
Angle
This sensor is factory calibrated.
Specifications
Maximum data-collection rate
1000 sample/second (gyro and
accelerometer)
2 sample/second (altimeter)
Acceleration range
±156.8 m/s
2
High acceleration range
±1960 m/s
2
(± 200 g)
Gyroscope range
±34.9 rad/s
Altitude range
–1800 m to 10,000 m
Angle range
±180°
USB specification
USB 2.0 full speed
Wireless specification
Bluetooth v4.2
Maximum wireless range
30 m (unobstructed)
Dimensions
68 mm × 27 mm × 17 mm
Least cross section
28.6 mm
Battery
300 mA Li-Poly
Battery life (single full charge)
~24 hours continuous data collection
Battery life (long term)
Several years depending on usage
Care and Maintenance
Battery Information
Go Direct Acceleration contains a small lithium-ion battery. The system is
designed to consume very little power and not put heavy demands on the