TURN ANGLE POTENTIOMETER INSTALLATION
SX TRANSISTOR CONTROL Page 55
July 1999
Section 7.0 TURN ANGLE POTENTIOMETER INSTALLATION
Section 7.1 General
The potentiometer used for the turn angle must be a 270 degree rotation device that is attached to the steer wheel in a manner to
cause a 1:1 rotation ratio between the two devices. Any ohm value potentiometer can be used, but it is suggested that it be at
least 2KW or above, to keep the wattage of the potentiometer to a minimum. The turn angle potentiometer provides a voltage
divider circuit that allows the left and right motor controller to determine the turn angle of the rear steer wheel of the vehicle.
The potentiometer is connected to the two controls as show in Figure 1. After the potentiometer is installed on the vehicle, it will
need to be adjusted to insure proper operation of the vehicle.
OPERATION:
To insure proper operation, the input voltage at P12 on both the left and right
controls must coincide with the turn angle of the steer wheel. When the steer
wheel is straight ahead ( Zero Degree Turn Angle), the input voltage at each
control should be 2.15 volts. As the vehicle turns left, this input voltage will
decrease, as the vehicle turns right, the input voltage will increase. The graph
in Figure 2 outlines the input voltages, the actions of the controls and the
corresponding turn angles of the steer wheel. A complete listing of input
voltages, steer angles and control actions can be found in Section 7.2 - 270
Degree Potentiometer Input. As an example of control operation as
compared to the input voltage, the following series of events takes place in a
left turn from the zero to 90 degree steer wheel position. In the first 16
o
of
travel ( 2.15 to 1.90 volts), there is no change to inside wheel speed. Between 16
o
(1.90V) and 78
o
(0.91V), the inside motor will
reduce its speed linearly from 100% on-time to the value set by Function 11. The inside wheel will reduce its speed
proportionally to the outside wheel speed, between 16
o
(1.90V) to 66
o
(1.10V). At an angle greater than 71
o
, the inside wheel
reverses and operates at the speed indicated by the setting of Function 11.
SETUP:
Before any adjustments are done. Jack up the drive wheels.
Install the potentiometer on the vehicle steer wheel in such a way to allow adjustment of the shaft with the potentiometer and
connected to both the left and right controls. Setup of the turn angle pot can be done in several ways, detailed below.
Volt Meter Method
Attach a volt meter, positive lead to P12 and negative lead to P20 of the control. Insure that the vehicle steering wheel is turned
so that the wheels are pointed straight ahead (and the steer angle pot is at the zero degree angle). Connect the battery and
adjust the potentiometer until the voltage between P12 and P20 is 2.15 volts. Complete the auto calibration routine for the steer
angle potentiometer as outlined in Section 8 of this manual.
P20
Section of Left Motor Control
(Master)
Section of Right Motor Control
(Slave)
P12P19 P12
4.3V Supply
Turn Angle Input
Supply Neg
Turn Angle Input
270 Degree
Potentiometer
Figure 1
To Next Page
Loading...
