Model 5200 High-Level Orderpicker
Section 8. Theory of Operation Wire Guidance System
When the Filter Card receives these signals, it filters unwanted frequencies, then processes these signals for the Guidance Manager card to use.
limited. The factory default setting for DFW stop is 3 in. (76 mm). If the distance is greater than 3 in. (76 mm), the travel comes to a controlled stop.
The Guidance Manager card compares the strength of four guidance signals (TL, TR, LL, LR) and determines the lift truck’s distance from wire (DFW) and heading angle (HA). The Guidance Manager card uses the DFW and HA to correct the steering via the STM.
The HA and DFW settings may be changed in the lift truck Configure Menu using FlashWare software. See “Wire Guidance” on page 3-8.
Heading Angle Settings Minimum
Maximum
Default
HA Slow
0.6°
2°
1.6°
HA Stop
2°
4°
1.6°
The heading angle is the angle between the direction the lift truck is pointed and the guide wire. The Guidance Manager card calculates the angle by comparing the TL, TR, LL and LR signals. For example, if the TL and LR signals are stronger than the TR and LL signals, the lift truck is pointed to the right of the guide wire. This calculation is compared to the configured settings of HA slow and HA stop. If HA slow is 1.6° and if the heading angle is greater than 1.6°, travel speed is limited. If HA stop is 3° and the heading angle is greater than 3°, travel comes to a controlled stop. Distance From Wire Settings Minimum
Maximum
Default
DFW Slow
0.6 in. (15 mm)
1.6 in. (41 mm)
1.6 in. (41 mm)
DFW Stop
1.2 in. (30 mm)
3 in. (76 mm)
3 in. (76 mm)
Distance from wire (DFW) is the distance the centerline of the lift truck is from the guide wire. The Guidance Manager card calculates this distance by comparing the TL, TR, LL and LR. For example, if the TL and LL are stronger than the TR and LR signals, the left guidance coils are closer to the guide wire than the right guidance coils. The factory default settings for DFW slow is 1.6 in. (41 mm). If this distance is greater than 1.6 in. (41 mm), travel speed is
When the Guidance Manager card calculates the HA and DFW, it sends a steering correction request to the Steer/Tractor Manager via the CAN bus (BUS+, BUS-). The Steer/Tractor Manager then tells the steer power head what direction to steer. This command causes the drive unit to turn. For example, if the Guidance Manager card calculates that the lift truck is 1 in. (25.4 mm) to the right of the wire, it tells the Steer/Tractor Manager to turn the drive unit and move the lift truck toward the left until all 4 guidance signals (TL, TR, LL, LR) are equal distance from the wire. While the drive unit is turning, the steer feedback encoder reports the amount the drive unit is turning. This encoder is mounted directly on the steer motor’s armature shaft and rotates with the steer motor. As the encoder turns, it sends two voltages, CHA and CHB, to the Steer/Tractor Manager. The Steer/Tractor Manager uses these voltages to track the drive unit position, then sends the information to the Guidance Manager card via the CAN bus. CHA and CHB change state from approximately 5 volts to 0 volts and back as the encoder rotates. The resulting number of times the 2 channels change state indicates how far the drive unit has turned. When the required amount of turning is sensed, the steer command is removed. Since the lift truck travels in relationship to the wire, when a steer request is carried out and the lift truck moves forward, the sensors’ relationship to the wire changes; therefore, the steer request changes. The change in request turns the drive unit the other way, monitored by the steer feedback encoder, until the lift truck is both parallel to and directly over the wire.
Publication Number: 1043922B, Revised: 2 Sept 2015
8-15
