Zapi EPS-AC0, User Manual, Page: 82 / 95

Page - 82/95 AEMZP0BA - EPS-AC0 - User Manual
13 OTHER FUNCTIONS
Here is a list of special functions hand set assisted, that are not documented yet.
13.1 Acquiring the Motor resistance
When it is possible, the steering motor is controlled sensorless. To get the best
performance in terms of the max torque generated, it is necessary to compensate
for the drop in the motor resistance. So the correct value of the motor resistance
must be known.
Eps-ac0 provides a self-acquisition procedure to acquire the motor resistance.
It is just enough to connect the eps-ac0 to the battery, to the motor and to the wiring
in order no alarm occurs. Then:
1) Enter the ADJUSTMENTS menu searching for ADJUSTMENT #01 setting.
2) Turn ADJUSTMENT #01 to Level 1. (A DATA ACQUISITION alarm occurs and
a half Imax DC current is automatically injected in the motor).
3) Wait about 2 secs.
4) Roll ADJUSTMENT #01 back to Level 0.
5) Save the new setting.
With this procedure the resistance between two motor terminals is automatically
measured and recorded (in milliohms) on the ADJUSTMENT #02 (see 12.4.2.3).
It is also possible to adjust the motor resistance value without self-acquisition by
rolling the ADJUSTMENT #02.
The acquisition of the motor resistance should be performed to find the correct value
when developing a new truck prototype; the correct value will be the default setting
for the mass production of that truck.
13.2 Alignment at the rest position
In the open loop applications (i.e. when the stepper motor is used in the steering
wheel or the steer command is a speed information coming via CAN bus) an
alignment at the rest position is automatically performed when the steered wheel
has a drift with a released steering wheel. This alignment at the rest position is
handled closed loop and so a feedback sensor is required. So this function is
performed only either with SYSTEM CONFIG to level 0 or with SYSTEM CONFIG to
level 4. When the feedback sensor uses a feedback potentiometer, the alignment at
rest position is performed for both cases (SYSTEM CONFIG to level 0 and 4)
provided that option LIMIT DEVICE is ON. When the feedback sensor uses toggle
switches, the alignment at the rest position is performed only when SYSTEM
CONFIG is level 0.
13.3 Straight ahead steering numbness
It is possible to reduce the steering sensitivity while the steered wheel is close to be
straight ahead by using the NUMBNESS setting in the PARAMETERS CHANGE
menu. Increasing the NUMBNESS parameter gets the steering less responsive
when the truck is driving next to the straight ahead direction (i.e. a certain increment
of the steering wheel angle gets a smaller increment of the steered wheel angle
when the truck is driving straight ahead than when it is angled).