Curtis 1239E - Page 45

Return to TOC Curtis 1239E-1269E Manual, os 37.0 RevA – May 2021
4 — PROGRAMMABLE PARAMETERS
pg. 41
1 - SPEED MODE — POSITION HOLD MENU
PARAMETER ALLOWABLE
RANGE
DESCRIPTION
Position Hold Enable
|Position_Hold_Enable
|Position_Hold_Enable_Bit0 [Bit 0]
On / Off
On / Off
[PCF]
Allows the Position Hold mode to be entered at zero throttle when the vehicle comes to
a stop.
NOTE: EM Brake Type = 2 also enables the Position Hold function.
Position Hold Timeout Time
Position_Hold_Timeout_Time
0.0 – 20.0 s
0 – 625
This parameter plus the Position Hold Settling Time parameter sets the maximum time
the vehicle will stay in Position Hold before releasing the hold and going into Restraint
mode. Setting the parameter to zero disables this timeout function, which means the
Position Hold will be held. Activating the interlock resets the timer.
Kp
Kp_Position_Hold
2 – 100%
82 – 2048
Determines the stiffness with which position is regulated when in Position Hold mode.
High Kp will produce less rollback on a ramp, but more bouncing; see Kd below. Too
much Kp will cause instability.
Kd
Kd_Position_Hold
0 – 100%
0 – 8192
Determines the damping in Position Hold mode. Some damping must be present in the
control system to keep the vehicle from oscillating slowly (“bouncing”). High Kd will
improve the dynamic response of the Position Hold controller, but too much Kd will cause
fast instability.
Zero Speed Threshold
Zero_Speed_Threshold
5 – 100 rpm
5 – 100
Determines the speed below which the EM brake will be commanded to set. Setting this
speed too high may cause a jerky stop when the EM brake sets and stops the motor.
This parameter appears twice in the menu structure. Changing the value of this parameter
affects this (same) parameter in the EM Brake Control menu.
Zero Speed Threshold Time
Zero_Speed_Threshold_Time
0 – 480 ms
0 – 60
Determines how long motor speed must be below Zero_Speed_Threshold to declare
zero speed.
This parameter appears twice in the menu structure. Changing the value of this parameter
affects this (same) parameter in the EM Brake Control menu.
Position Hold Settling Time
Position_Hold_Settling_Time
0 – 5000 ms
0 – 156
Determines how long the position hold function is allowed to operate before the EM brake is
set. This time should be set long enough for the position hold to settle.
This parameter appears twice in the menu structure. Changing the value of this parameter
affects this (same) parameter in the EM Brake Control menu.
Entry Rate
Entry_Rate_Position_Hold
5 – 100%
50 – 1000
When the vehicle transitions from forward speed to reverse speed or from reverse speed
to forward speed (for example when coming to a stop going up a steep ramp) Position
Hold is automatically entered immediately at zero speed regardless of this parameter.
This parameter applies when the vehicle needs to be brought to a stop without the
assistance of gravity (for example when moving forward down a ramp). This rate
determines how quickly zero speed is attained after the ramped speed request reaches
zero. Setting this parameter too high will make the stop seem very abrupt and may even
cause the vehicle to roll back slightly. When the parameter is set lower the vehicle take
longer to come to a stop and enter Position Hold mode.
Exit Rollback Reduction
Exit_Rollback_Reduction
0 – 100%
0 – 2048
This function is applicable when the Torque Preload Enable function has been Disabled
(Off) or the Torque Preload Cancel Delay timer has expired (see EM Brake menu). Exit
Rollback Reduction is only intended for use with EM Brake Type = 2, for EM Brake Type =
1 (or 0) set Exit Rollback Reduction = 0.
Exit Rollback Reduction introduces an additional control function for the speed controller to
reduce rollback on a ramp after a throttle command is applied from a stop. For example,
suppose the vehicle is on a ramp facing upwards and, after a forward throttle request, the
vehicle rolls back slightly before climbing the ramp (again, assuming the torque preload
function is inactive). As the vehicle rolls back, this additional term will be added to the torque
request until forward speed is sensed, to attempt to minimize rollback. The effect increases
with percentage, and is disabled when = 0%. Setting the value too high may introduce
temporary oscillations.
If the Torque Preload Cancel Delay expires before the throttle is re-engaged, the torque
preload [Position Hold] memory will be cleared. In such a case, setting Exit Rollback
Reduction to > 0% will reduce unintended roll.
Quick Links:
EM Brake Type p.52
Torque Preload Enable p.53
Torque Preload Cancel
Delay p.53