US Patent:
20020154948, Oct 24, 2002
Inventors:
Vernon Brabec - Livermore CA, US
Wai Chan - San Ramon CA, US
Raymond O'Connor - Danville CA, US
Assignee:
TOPCON LASER SYSTEMS, INC.
International Classification:
E01C007/06
Abstract:
A method is disclosed for a controller to automatically switch to an alternative control mode to control the height of a grading implement when the output of a positioning sensor is not available. According to the invention, the controller recognizes sensor unavailability and automatically switches to an alternative operating mode to maintain control. In one alternative operating mode, the controller recognizes sensor unavailability and automatically routes the control signal from the unaffected side to the control channel for the affected side. In another alternative operating mode, the controller monitors the current value of an additional sensor for an alternative mode of control until one of the primary sensors becomes unavailable, and then automatically switches to the alternative mode for the affected side, using the last known value for the alternative mode as the set point.