4 — PROGRAMMABLE PARAMETERS
pg. 53
Return to TOC Curtis AC F2-A, F4-A, F6-A Motor Controllers – FOS 4.5 – April 2022
SPEED MODE/SPEED CONTROLLER — ACC FEEDFORWARD MENU
PARAMETER ALLOWABLE RANGE DEFAULT DESCRIPTION
Kaff
Kaff_SpdM
0x3828 0x00
0 – 500A
0 – 5000
0 Amp The design of the acceleration feedforward term is to improve
throttle responsiveness and speed controller performance at
all speeds.
As a quick start function, it enhances the responsiveness at all
speeds. This acceleration feedforward is a constant value applied in
the direction of travel during acceleration.
Set this parameter while using the application’s present Accel and
Decel rates by observing the average current while running full
throttle at low speeds, accelerating without a load on at ground.
Set Kaff to 50–70% of that value.
Note: If any Accel rate parameters change, this parameter will
also need to be changed (updated).
Kbff
Kbff_SpdM
0x3829 0x00
0 – 500A
0 – 5000
0 Amp The design of the braking feedforward term is to improve braking
responsiveness at all speeds. This braking feedforward is a
constant value applied opposite the direction of travel during
braking or deceleration.
Using the application’s present decel rates, observe the average
current at full throttle braking and set Kbff to that value.
Build Rate
Acc_FF_Build_Rate_SpdM
0x3808 0x00
0.1 – 5.0 s
100 – 5000
1.0 sec Determines how fast the Kaff and Kbff terms build up.
For traction systems, if the mechanical lash (slop) picks up
abruptly when moving the throttle from neutral to a very small
value, slowing the build rate (i.e. setting it to a higher value) will
soften the feel.
For a pump system, start with this parameter at the minimum
setting. Slowing it down (i.e. setting it to a higher value) will
reduce speed over-shoot if too much feedforward has
been commanded.
Release Rate
Acc_FF_Release_Rate_SpdM
0x3809 0x00
0.1 – 5.0 s
100 – 5000
0.4 sec Determines how fast the Kaff and Kbff terms release. It should be
set fast enough (i.e. at a low enough value) to prevent the vehicle
from running on after throttle release.
SPEED MODE/SPEED CONTROLLER — VEL FEEDFORWARD MENU
PARAMETER ALLOWABLE RANGE DEFAULT DESCRIPTION
Kvff
Kvff_SpdM
0x3832 0x00
0 – 500A
0 – 5000
0 Amp The design of the velocity feedforward term is to improve throttle
responsiveness and speed controller performance, especially at
low speeds. This velocity feedforward is a constant value in the
direction of the velocity trajectory.
For traction systems set it to 50–70% of the current needed to
maintain a very low speed unloaded on at ground.
For a pump system set it to the lowest load current (i.e. the current
running at the minimum load). Alternatively, the responsiveness of
a pump speed-control-loop is typically enhanced by using a VCL
program to continuously update this parameter to the appropriate
value as each pump load is requested.
Build Rate
Vel_FF_Build_Rate_SpdM
0x385F 0x00
0.1 – 5.0 s
100 – 5000
1.0 sec Determines how fast the Kvff term builds up.
For traction systems if you feel or hear the mechanical lash
(backlash) pick up abruptly when you move the throttle from
neutral to a very small value, slowing the build rate (i.e. setting it
to a higher value) will soften the feel.
For a pump system start with this parameter at the minimum
setting. Slowing it down (i.e. setting it to a higher value) will reduce
speed over-shoot if too much feedforward has been commanded.
Release Rate
Vel_FF_Release_Rate_SpdM
0x3860 0x00
0.1 – 5.0 s
100 – 5000
0.4 sec Determines how fast the Kvff term releases.
If the release seems too abrupt, slowing the release rate (i.e.
setting it to a higher value) will soften the feel. It should be set
fast enough (i.e. at a low enough value) to prevent the vehicle
from running on after throttle release.
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