Autc At Key-On; Autc On-Demand; Operational Features - Zapi EPS-AC0 SWs&ENC User Manual

3.2.1 AUTC at key-on

When AUTOCENTERING is ON, the AUTC at key-on is always performed.
When AUTOCENTERING is OFF, the AUTC at key-on is always performed but in
case of open loop system without electrical steered wheel angle limitation (i.e. no
AUTC at key-on when the stepper motor is used and 1
are both set to level 9).
The AUTC at key-on is used to initialize the encoder counting. When it is not
performed, the truck travels slow speed only, until the driver moves the steering
wheel and an edge is detected on the straight ahead sensor getting possible the
initialization of the encoder counting .
When closed loop (twin pot at the handle bar) the AUTC at key-on is always
performed.

3.2.2 AUTC on-demand

When option AUTOCENTERING is ON, function AUTC on-demand is available.
When option AUTOCENTERING is OFF, centering on-demand is available but it is
not automatic.
In both cases the centering on-demand needs a centering request to be performed.
The centering request can be provided via CAN Bus. As alternative, it is possible to
use wired request. For example it is possible to use the general purpose analog
input CNB#6. In case of a single (not redundant) centering request, the centering
will be performed only when the truck is at rest. To know when the truck is at rest
input CNA#1 is available for receiving a travel demand or a dead man switch
request.
To perform a centering on-demand when the truck is moving, redundancy is
recommended in the wired request (i.e. a second request on a remote module is
recommended).
AUTC on-demand is not handled in the standard eps_ac0. Software modification are
required on customer specification.
Anyway, the handling will be:
1) When AUTOCENTERING is ON and the centering request turns on, the steered
wheel rotates by itself to the closest straight ahead position. For application without
electrical steered wheel angle limitation, the closest straight ahead position may be
either the WHEEL ANGLE to 0 degrees or the WHEEL ANGLE to 180 degrees. For
applications with electrical steered wheel angle limitation, the AUTC on-demand is
always performed on the WHEEL ANGLE to 0 degrees position.
2) When AUTOCENTERING is OFF and the centering request turns on, only
manually centering is possible. In fact the steered wheel position will be captured
inside a very narrow window around the closest straight ahead position: the driver
takes in charge for moving the steered wheel inside the narrow window by turning
the steering wheel.

3.3 Operational features

A list of eps-ac0 operational features follows below:
1) Static sensitivity boost in open loop (steering sensitivity increases for a slow
moving steering wheel).
2) Static numbness in closed loop (steering sensitivity decreases for handle steer
close to the straight-ahead direction).
3) Dynamic Numbness in open loop (steering sensitivity reduces when the truck
speed increases).
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