VC4000DAQ Manual
71
To set Defaults:
1. Select
Set Defaults
from the Setup menu
2. Press
ENTER / YES
.
3. Press
ENTER / YES
again.
All VC4000’s have a date chip that maintains time and date even in
the absence of power. It contains a
lithium battery
supply, which
will last a minimum of 10 years. The time and date of each run is
stored in memory and then uploaded to Profile and stored in the
header of Profile for each run. This is useful if the file numbers do
not correlate to the test number because you have had to clear
memory after making some tests. At least you have the time of day
for a reference point.
1. Select
Date/Time
from the Setup menu
2. Set the time for your time zone by entering every number,
including zeros. To enter time of 9:00 enter 0, 9, 0, 0.
3. Enter 1 for am or 2 for pm after the digits are entered.
4. Enter the date including zeros. After the date is entered the
VC4000 sets the time and date in memory.
5. Alternatively use
Profile
to set the time and date to your
computers time and date.
CLEAR / NO
may be pressed anytime to abort setting the time and
date.
Enter the pitch and roll factors. The default is 1 for each. Pitch is the
front-to-back tilt, and roll is the side-to-side tilt. If G summation is
either 2D (XY) or 3D (XYZ) the VC4000 will use the Gx pitch factor
for the adjustment. Gy (roll) and Gz adjust will have no affect.
Pitch/Roll Factors
Date/Time
VC4000 Setup
VC4000DAQ Manual
72
Figure 27: Vehicle axes
The VC4000 is affected slightly by the tilt of the car caused by
suspension shifts under acceleration or deceleration. This effect is
slight and for the purposes of the VC4000 is considered to be similar
for all vehicles designed to be driven on the highways including
motorcycles, passenger cars, semi tractor trailers and most off road
vehicles. The VC4000 is set at a common pitch and roll factor (factor
1) for all vehicles with useful suspension systems.
The VC4000 is shipped with Pitch factor and Roll factor of 1, which is
an adjustment of 0.9700. The Pitch and Roll adjustment can be
finely adjusted using G adjust.
Using the VC4000’s built in rate gyro the pitch and roll can be
measured. To measure pitch first turn the rate gyro on, see page 79.
Next, mount the VC4000 so the left side of the unit is facing down
and the display is facing the back of the vehicle, as usual. Perform a
brake test. Import the data to Profile and look at the graph of the
rate gyro.
The curve should go down then come back to 0 when the car is fully
pitched down. If you add up all the samples from when the curve
went down to when it came back up and multiply by the time, you
should get the pitch in degrees. For example if you had 0.25
seconds of pitch and they added up to 9.2 deg/sec, then take 9.2 *
0.25 to get 2.3 degrees of pitch. Use a calculator to find the sine of
2.3, 0.040, then subtract that from 1.000 to get 0.960 and that is the
G-adjustment (Pitch Factor) for that particular vehicle.
Summary: 9.2deg/sec * 0.25sec = 2.3 degrees. Sine 2.3 = 0.040. 1
- 0.040 = 0.960 pitch factor.
