초록 ▼

A method and apparatus for automatically controlling the depth of earth grading for utilization with a grader or paver is disclosed. The method includes determination of time taken for an acoustic pulse to travel from a transducer to a reference surface and back, with this value being used to calibr

A method and apparatus for automatically controlling the depth of earth grading for utilization with a grader or paver is disclosed. The method includes determination of time taken for an acoustic pulse to travel from a transducer to a reference surface and back, with this value being used to calibrate a microprocessor-controlled distance-measuring device. As the grader moves over a surface to be graded, the distance to the reference surface is constantly detected by a repeated emission and detection of such acoustic pulses. The timing of the echoed pulses is converted to addresses in a look-up table which contains control words symbolizing commands to be given to hydraulic rams carried by the grader. By implementing these commands, the depth of the blade relative to the reference surface is constantly updated, compensating for variations with the height of the reference surface. A thermistor is provided to automatically compensate for temperature variations as the grading takes place. Displays are provided for the operator of the vehicle to show what type of adjustments are being made to the blade, and whether the height of the reference surface is outside the range of sensitivity of the follower. The follower is automatically calibrated for a given blade depth by repeated incrementation of a delay time variable until a zero adjustment command is generated for the blade control.

대표청구항 ▼

A method of controlling a hydraulic system for grading a first surface at a chosen depth relative to a reference surface by means of an earth grader carrying a vertically adjustable blade at the chosen depth relative to the reference surface by action of the hydraulic system on the blade, including

A method of controlling a hydraulic system for grading a first surface at a chosen depth relative to a reference surface by means of an earth grader carrying a vertically adjustable blade at the chosen depth relative to the reference surface by action of the hydraulic system on the blade, including the steps of: implementing a calibration procedure, including determining a reference time interval relating to a travel time of an acoustic pulse from a transducer to the reference surface and back to the transducer, so that the reference time interval corresponds to the chosen depth of the blade as determined by an operator of the earth grader; emitting a ranging pulse from the transducer toward the reference surface and starting a counter at a first time, the transducer being mounted in a fixed position relative to the blade, such that the ranging pulse reflects from the reference surface back toward the transducer; stopping the counter when the reflected ranging pulse reaches the transducer, thereby generating a count corresponding to the length of time taken by the ranging pulse to reflect from the reference surface back to the transducer and further corresponding to an actual blade depth; vertically adjusting the blade by a distance relating to the count such that the actual blade depth corresponds to the chosen blade depth; repeating the steps of emitting the ranging pulse, starting and stopping the counter, and vertically adjusting the blade, whereby variations in the height of the reference surface are automatically compensated by the adjustments of the blade as the grader moves along the reference surface; and compensating the adjustments of the blade for temperature variations after the reference time interval has been determined, and before each time the ranging pulse is emitted.