Zapi EPS-AC0, User Manual, Page: 9 / 95

AEMZP0BA - EPS-AC0 - User Manual Page - 9/95
3 FUNCTIONS OF THE EPS-AC0
The eps-ac0 controls a steer system for warehouse trucks. It executes the following
functions:
1) Manual mode steering
2) Automatic
Centering.
3.1 Manual Mode Steering
Manual mode steering requires a command sensor in the hand wheel. The hand
wheel may be of two types:
1) Multiturn steering wheel without end-strokes.
2) Handlebar, tiller or joy-stick with end-strokes to limit the angle.
With a Multiturn steering wheel, the sensor in the hand-wheel shall be a stepper
motor used as a tacho-generator (see Figure 3-1). Then the control will turn the
steering motor moving at a speed proportional to the stepper motor speed (Open
loop Mode).
Stepper Motor
Figure 3-1
With a Handlebar (tiller or joy-stick), the sensor in the hand-wheel will be a twin pot
(see Figure 3-2 below). Then the system works as a position control loop with a rigid
correspondence between the angle of the handlebar and the angle of the steered
wheel (Closed Loop Mode). In this case a feedback sensor on the steered wheel is
mandatory.