Calibration system and method for work machines using electro hydraulic controls

• US 6,615,114 B1
• Filed: 12/15/1999
• Issued: 09/02/2003
• Est. Priority Date: 12/15/1999
• Status: Expired due to Term

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Stratton, Kenneth L., Clar, Jean-Jacques, Skiba, Richard J., Genseal, Steven R.
• Primary Examiner(s): Picard, Leo
• Assistant Examiner(s): RODRIGUEZ, PAUL L
• Application Number:
  US09/464,469
• Time in Patent Office: 1,357 Days
• Field of Search: 700/32, 700/33, 700/56, 700/57, 700/60-64, 700/85, 700/90, 700/250, 700/254, 700/275, 700/281, 700/282, 700/301, 700/302, 372/34, 379/02, 702/85, 702/105, 702/94, 701/50, 172/2, 172/3, 172/9, 172/10, 73/10.1
• US Class Current: 700/275
• CPC Class Codes: E02F 9/2025 Particular purposes of control systems not otherwise provided for E02F3/16, E02F3/26, sub-groups of E02F3/43, E02F3/651, sub-groups of E02F3/84, E02F3/907, E02F5/145 take precedence
• CPC Class Codes: F15B 13/0442 with proportional solenoid allowing stable intermediate positions
• CPC Class Codes: F15B 19/002 Calibrating
• CPC Class Codes: G01L 27/005 Apparatus for calibrating pressure sensors

Abstract

A calibration system for use on a work machine wherein electro hydraulic controls are utilized to control the operation of a particular work element, the present calibration system being operable in both a semi-automatic mode and an automatic mode. In the semi-automatic mode, operator interaction is required and the calibration process is preferably initialized and controlled via a service tool which is in communication with a work machine controller. A command signal having a command signal value indicative of a command state of the component being calibrated is generated by a command signal generator, and a detector in communication with the component receives the component signal and detects when the component has reached the command state, and generates a detector signal having a value representing a calibration factor to be used in correlating the component signal value with the actual state of the component. In the automatic mode, no operator interaction is required and the controller automatically and dynamically correlates and compares the current state of the particular component being calibrated with its last stored state and thereafter calibrates the component upon detecting a difference therebetween.

Claims

1. A calibration system for a work machine using an electro hydraulic valve to control the operation of a work element, the work machine for use in a location having an atmospheric pressure, the valve being connected to the work element via a hydraulic circuit which includes actuator means coupled to the work element for controlling the operation thereof, the calibration system comprising:

a pressure sensor positioned in communication with the valve and adapted to sense a pressure being exerted against the work element, the pressure sensor outputting a pressure sensor signal having a pressure sensor signal value indicative of the sensed pressure; and

a controller in communication with the pressure sensor and adapted to automatically and dynamically calibrate the pressure sensor signal value to the atmospheric pressure, the controller comprising;

storage means for storing the atmospheric pressure;

a comparator in communication with the pressure sensor and adapted to compare the stored atmospheric pressure to the pressure sensor signal value of the received pressure sensor signal at atmospheric pressure;

a detector in communication with the comparator and adapted to detect a difference between the stored atmospheric pressure and the compared pressure sensor signal value at atmospheric pressure; and

a calculator adapted to calculate an atmospheric pressure calibration factor representing the detected difference such that accurate control of the pressure sensor is achieved.

2. The calibration system as set forth in claim 1 wherein the controller includes pre-calibration verification means for verifying a plurality of pre-calibration conditions during calibration of the pressure sensor.

3. A method of calibrating a pressure sensor of a work machine using an electro hydraulic valve to control the operation of a work element, the work machine for use in a location having an atmosphere pressure, the valve being connected to the work element via a hydraulic circuit which includes actuator means coupled to the work element for controlling the operation thereof, the pressure sensor positioned in communication with the valve and adopted to sense a pressure being exerted against the work element, the pressure sensor outputting a pressure sensor signal valve indicative of the sensed pressure, the method comprising the steps of:

storing a value indicative of an atmospheric pressure;

comparing the stored value indicative of the atmospheric pressure to the pressure sensor signal value of the pressure sensor signal at atmospheric pressure;

detecting a difference between the stored value indicative of the atmospheric pressure and the compared pressure sensor signal value at atmospheric pressure; and

calculating an atmospheric pressure calibration factor representing the detected difference such that accurate control of the pressure sensor is achieved.

4. The method as set forth in claim 3, further comprising the step of verifying a plurality of the pre-calibration conditions.

5. A calibration system for a work machine using an electro hydraulic valve to control the operation of a work element, the work machine for use in a location having an atmospheric pressure, the valve being connected to the work element via a hydraulic circuit which includes actuator means coupled to the work element for controlling the operation thereof, the calibration system comprising:

a pressure sensor positioned in communication with the valve and adapted to sense a pressure being exerted against the work element, the pressure sensor outputting a pressure sensor signal having a pressure sensor signal value indicative of the sensed pressure; and

a controller in communication with the pressure sensor and adapted to automatically and dynamically calibrate the pressure sensor signal value to the atmospheric pressure, the controller comprising;

storage means for storing the atmospheric pressure;

a comparator in communication with the pressure sensor and adapted to compare the stored atmospheric pressure to the pressure sensor signal value of the received pressure sensor signal at atmospheric pressure; and

a calculator adapted to calculate an atmospheric pressure calibration factor in response to the stored atmospheric pressure and the received pressure sensor signal.

6. A method of calibrating a pressure sensor of a work machine using an electro hydraulic valve to control the operation of a work element, the work machine for use in a location having an atmosphere pressure, the valve being connected to the work element via a hydraulic circuit which includes actuator means coupled to the work element for controlling the operation thereof, the pressure sensor positioned in communication with the valve and adopted to sense a pressure being exerted against the work element, the pressure sensor outputting a pressure sensor signal valve indicative of the sensed pressure, the method comprising the steps of:

storing a value indicative of an atmospheric pressure;

comparing the stored value indicative of an atmospheric pressure to the pressure sensor signal value of the pressure sensor signal at atmospheric pressure; and

calculating an atmospheric pressure calibration factor in response to said atmospheric pressure and said pressure sensor signal value.