Patent ID: 6152238
Filing Date: 2000-11-28
Classification: E02F,G01S

Abstract:
A construction tool grade and elevation establishing control for maintaining the vertical position of the construction tool relative to a reference, said construction tool being carried by a tool frame of a construction apparatus, the tool frame being supported for horizontal motion and being adjustably positioned by a hydraulic-tool-positioning device, the hydraulic-tool-positioning device having at least one solenoid operated hydraulic valve and being responsive to signals of a particular configuration from said construction tool grade and elevation establishing control to adjust the position of the construction tool, said construction tool grade and elevation establishing control comprising:at least one sensor configured to be carried by a construction tool, said sensor generating wave signals and sensor signals, said sensor detecting reflections of said wave signals from a reference, and said sensor signals being generated by said sensor in response to said sensor detecting said reflections and being a function of said reflections and the distance of said sensor to the reference; anda sensor control coupled to said at least one sensor, said sensor control being in communication with and driving said sensor to generate said wave signals and determining the position of the construction tool relative to the reference based on said sensor signals, said sensor control evaluating each of said sensor signals and determining whether said sensor signals represent valid or invalid sensor signals, said sensor control producing an enable signal in response to detecting a valid sensor signal and transmitting said enable signal to solenoid operated hydraulic valve to adjust the position of the construction tool to maintain a desired position of the construction tool with respect to said reference and generating a disable signal in response to detecting an invalid sensor signal and transmitting said disable signal to said solenoid operated hydraulic valve whereby the position of the tool remains substantially unchanged, and said sensor control being adapted to detect a particular configuration of the at least one solenoid operated hydraulic valve, and said sensor control producing said drive signal based on the configuration of the at least one solenoid operated hydraulic valve.