6 — VEHICLE PERFORMANCE ADJUSTMENT
1212 & 1212P Manual - Sep 2019
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pg. 34
Step 7: Adjusting IR compensation
e IR Comp parameter is used to set the percentage of the maximum motor resistance that will be
applied, i.e., (IR Comp) × (System Resistance), to compensate for increased load caused by uneven
terrain.
e trade-o in setting this parameter is that as ability to overcome load disturbances increases,
operating smoothness decreases. A high IR Comp value will allow the vehicle to continue creeping at
a low speed, even though it has just contacted a bump in the threshold of a doorway. But if IR Comp
is set too high, it may make the vehicle “jumpy” during normal driving. Small throttle movements
in this case may no longer provide gentle linear acceleration, but instead initiate accelerations with a
sharp jerk. erefore, the tuning goal is a balance between adequate load disturbance response and
normal acceleration/deceleration response.
e normal range for IR Comp is approximately 50–80%. Larger numbers provide stier, stronger
response. If the value needs to be much larger or smaller than this range to achieve acceptable
performance, the System Resistance has probably not been set up correctly and should be checked.
Note: Largely dierent settings for IR Comp will aect the maximum speeds that were set in Step 5.
erefore, if you make large changes to IR Comp, you should repeat Step 5.
Just before stopping, when the throttle is in neutral, IR Comp is replaced by Anti-Rollback Comp.
Typically Anti-Rollback Comp is set about 20% higher than IR Comp.
Assuming that System Resistance is set correctly (within 10–20%), some general rules of thumb
apply:
a. If the vehicle is extremely “jumpy” (i.e., responds abruptly to small throttle changes, IR Comp
could be set too high.
b. If the vehicle speed varies dramatically when cresting a hill, IR Comp is most likely set too low.
c. If the vehicle rolls the other direction near the end of a stop on at ground, Anti-Rollback Comp
is set too high.
d. If the vehicle is still moving on a modest ramp when the brake gets set, Anti-Rollback Comp is
set too low.
e. If the vehicle seems to decelerate to a stop in a nonlinear fashion, Anti-Rollback Comp could
be set too high.
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