MEMS Digital Inclinometer System with Android
Instruction Manual
ICM0099A
4
D
UMMY
P
ROBE
Dummy inclinometer probes are available for purchase from RST for testing purposes in a
borehole. RST encourages customers to try the new digital dummy probe in existing holes
where the competitor’s probes do not work. If it is found that the dummy probe passes
through all areas of the casing, the RST MEMS Digital Inclinometer System will function.
Therefore, the existing hole will still be viable, and a new hole will not need to be drilled.
The RST dummy probe has the exact same weight and dimensions as the standard probe.
A ring is provided in place of the connector which allows the dummy probe to be lowered by
a rope. For further information on purchasing a RST Dummy Probe, please contact RST
Instruments Ltd.
S
IGN
C
ONVENTION AND
M
EASURED
D
EVIATION
The Digital Inclinometer Probe houses two MEMS accelerometers, which measure tilt in two
axes. Proper installation of the inclinometer casing attempts to align one set of grooves in
line with the axis of expected movement. This is called the
A axis
. The perpendicular set of
grooves is the
B axis
.
When an inclinometer casing is surveyed for the first time (i.e. baseline readings), it is
necessary to select a fixed direction reference for the probe so that each time a survey is
repeated, the probe will always have the same orientation in the casing.
For example, in an area suspected of landslide activity, the first set of readings would be
taken by placing the upper wheels of the probe in the casing groove closest aligned to the
downslope direction.
illustrates an inclinometer casing installed with a groove
orientation in the general downslope direction.
In practice, it is often difficult to achieve exact orientation of grooves relative to some
predetermined direction. The groove closest to the anticipated movement direction is usually
chosen as the main reference direction. It is recommended that this direction (A+) be
marked on the casing itself to ensure surveys are performed in the same manner each time.
The azimuth of this groove direction can be measured in a clockwise direction from the main
reference direction (A+). All subsequent measured inclinometer movements would be
referred to this direction.
Readings taken from the inclinometer probe (see Section 2.3) are actually deviations from
the vertical over the distance between the upper and lower wheels (see Figure 4), calculated
as:
D = L × sine(
α)
Where:
D = Deviation, e.g. lateral displacement in the direction of the axis of
measurement
L = inclinometer probe length (typically 0.5 m for a metric probe or 2 ft for an
imperial probe, as defined in Section 10).
α = inclination angle of probe from vertical axis
