Calculation Method; Testing Method - Curtis 1222 Manual

5 — COMMISSIONING
86
2 9 J A N U A R Y 2 0 1 3 D R A F T
d. The correct settings for
be either calculated or determined by testing.

Calculation method:

Encoder Counts/Degree = Gear Ratio * Encoder PPR * 4/360
Note: The factor of 4 in the equation accounts for the number
of edges in one encoder pulse (rising phase A, falling phase A,
rising phase B, falling phase B).
Example: Steer motor gearbox ratio = 45:1
Big gear around steer motor = 80 teeth
Small gear around steer motor shaft = 20 teeth
Encoder 3 steps (pulses per revolution) = 32.
The overall Gear Ratio = 45 * 80/20 = 180:1.
Encoder3 Counts/Degree = Gear Ratio * Encoder PPR * 4/360
= 180 * 32 * 4/360 = 64.

Testing method:

Use the steer command input to move the wheel position to a known
angle. For best accuracy, choose a known angle as far as possible
from the Home switch; this will usually be either the Left stop or
the Right stop. If you cannot reach the "known angle," most likely
the present setting of
check whether Monitor» Position Feedback»
Right Stop Reached
will move the Left and Right stops out, allowing more movement
of the steered wheel.
When the wheel position reaches the "known angle" (usually either
the Left or Right stop), observe the two variables Monitor» Position
Feedback» Encoder Input»
Counts from Home
between the known angle and the Home switch to get the Encoder
Counts/Degree for both encoders.
Example: Home Switch is at -4°
Left Stop (deg)
Right Stop (deg)
Use the steer command input to steer the wheel to a 90° position.
(This is the confirmed physical steer angle and may not agree
with the monitored wheel position variable.) Observe the variables
Monitor» Position Feedback» Encoder Input»
Home and Encoder4 Counts from Home
Encoder3 Counts from Home
Encoder4 Counts from Home
6016/90 - (-4) = 6016/94 = 64
So set
Encoder3 Counts/Degree
3008/90 - (-4) = 3008/94 = 32
So set
Encoder4 Counts/Degree
and
Encoder3 Counts/Degree
Encoder# Counts/Degree
= On. Decreasing the
Encoder# Counts/Degree
Encoder3 Counts from Home
. Divide these values by the number of degrees
set to 90°
set to 90°.
.
= 6016
= 3008.
= 64.
= 32.
can
Encoder4 Counts/Degree
is too high; you can
Left Stop Reached or
values
and Encoder4
Encoder3 Counts from
Curtis 1222 Manual,
os 15