Figure 29 - Illustration of s-curve on torque demand
The controller provides an option to insert an s-curve to the torque demand as it approaches the value
requested by the throttle. This curve feature can serve two purposes:
The amount of curve applied can be configured in the object dictionary at index 2933
h
. Generally,
applying a greater curve range will result in smoother drive, but too much can lower vehicle response. S-
curve is applied according to this table:
Table 23 – Torque S-curve configurations
This table continues, with each increment in 2933
h
doubling the range over which the curve is applied.
Scenarios
For certain vehicle types, particularly on-highway vehicles or electric motorcycles, the possibility of
wheel locking during drive must be considered.
During braking, the controller will maintain a speed limit to ensure the vehicle does not over speed if
entering braking whilst travelling downhill. If proportional speed limit is set then the speed limit will
follow actual speed toward zero whenever actual speed is dropping rapidly, usually due to some external
influence such as application of mechanical brakes.
If the brakes are applied too harshly, then there is possibility to lock the drive wheels. In these
circumstances, the normal reaction of the driver is to release the brake to allow the wheels to rotate
again. The correct operation of the controller in this scenario is to allow the wheels to continue to rotate,
and not impose a speed limit.
The maximum rate at which the speed limit can increase or decrease is specified in object 291E
h
. By
limiting the rate at which the speed limit can decrease, we can ensure that if the brakes are released after
they had locked the drive wheels, the controller’s speed limit will allow them to rotate again. The
operation of this is shown in Figure 30 below.
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