Calibration system and method of using same

• US 4,263,803 A
• Filed: 05/04/1979
• Issued: 04/28/1981
• Est. Priority Date: 05/09/1978
• Status: Expired due to Term

• Current Assignee: Ex-Cell-O Corporation
• Original Assignee: Ex-Cell-O Corporation
• Inventors: Burkhardt, Allan D.
• Primary Examiner(s): Ruehl, Charles A.
• Application Number:
  US06/036,264
• Time in Patent Office: 725 Days
• Field of Search: 73/1 R, 73/1 J, 33/174 L, 33/174 PC, 209/601, 209/604, 209/605, 324/75, 324/130
• US Class Current: 73/1.81
• CPC Class Codes: G01D 18/008 with calibration coefficients stored in memory
• CPC Class Codes: G01D 3/028 mitigating undesired influences, e.g. temperature, pressure

Abstract

A calibration system for automatically and sequentially calibrating a plurality of electrical measuring systems of a gauging machine is provided. Each measuring system is of the type having a gain circuit, a zero circuit and a combination circuit connected to the preamplifier of a transducer and the zero circuit for combining the output signals of the preamplifier and zero circuits to obtain unamplified compensated electrical input signals which are amplified by the gain circuits and indicated on an indicator. Each of the measuring systems produces an electrical measurement in a predetermined range defined by upper and lower bounds equal in magnitude but opposite in polarity. The calibration system includes a plurality of negative voltage references and a plurality of positive voltage references corresponding to the lower and upper bounds, respectively. The transducers are first moved to the negative voltage references by a servo system to obtain a plurality of first input signals which are sequentially compared under control of a sequence controller and a multiplexer to a fixed reference signal corresponding to the lower bound by a window comparator. The transducers are then moved to the positive voltage references to obtain a plurality of second input signals. The second input signals are processed, the processed signals being sequentially compared to a fixed reference signal corresponding to the upper bound.

Claims

1. A calibration system for calibrating an electrical measuring system, of the type having a gain circuit, a zero circuit and a combination circuit to obtain compensated electrical input signals, the measuring system producing an electrical measurement in a predetermined range defined by upper and lower bounds of opposite polarity, said calibration system comprising:

first and second reference means for providing first and second references corresponding to the lower and upper bounds, respectively, of the predetermined range of the measuring system when calibrated, the uncalibrated measuring system providing first and second electrical input signals of opposite polarity upon measuring said first and second references, respectively,

third reference means for providing reference signals,

comparator means for comparing reference signals to corresponding compensated input signals, and outputting corresponding adjustment signals corresponding to the difference therebetween,

zero adjustment means for adjusting the zero circuit in response to a first adjustment signal, wherein the electrical measuring system outputs a compensated input signal corresponding to the lower bound, and

gain adjustment means for adjusting the gain circuit in response to a second adjustment signal wherein the electrical measuring system outputs a compensated input signal corresponding to the upper bound.

2. The calibration system as claimed in claim 1 wherein said calibration system includes a polarity detector means for detecting the polarity of said input signals to characterize said adjustment signals, said zero adjustment means being responsive to said polarity detector means.

3. A calibration system for automatically calibrating an electrical measuring system of a gauging machine, the measuring system of the type having a gain circuit, a zero circuit and a combination circuit to obtain compensated electrical input signals, the measuring system producing an electrical measurement in a predetermined range defined by upper and lower bounds, said calibration system comprising:

first and second reference means for providing first and second references corresponding to the lower and upper bounds, respectively, of the predetermined range of the measuring system when calibrated, the uncalibrated measuring system providing first and second electrical input signals upon measuring said first and second reference means, respectively, wherein the gauging machine includes drive means for positioning the measuring device and the first reference means in operative relationship to obtain the first input signal and for positioning the second reference means and the measuring device in operative relationship to obtain the second input signal,

control means for controlling the gauging machine, wherein said control means controls the drive means and is responsive to signals from the gauging machine indicating said operative relationship to control the calibration process,

third reference means for providing reference signals,

comparator means responsive to said control means for comparing reference signals to corresponding compensated input signals and outputting corresponding adjustment signals corresponding to the differences therebetween,

zero adjustment means responsive to said control means for adjusting the zero circuit in response to a first adjustment signal wherein the electrical measuring system outputs a compensated input signal corresponding to the lower bound, and

gain adjustment means responsive to said control means for adjusting the gain circuit in response to a second adjustment signal wherein the electrical measuring system outputs a compensated input signal corresponding to the upper bound.

4. The system as claimed in claim 3 wherein the upper and lower bounds are of opposite polarity and said corresponding input signals are of opposite polarity and wherein said calibration system includes a polarity detector means for detecting the polarity of said input signals to characterize said adjustment signals, said zero adjustment means being responsive to said polarity detector means.

5. The system as claimed in claim 3 or claim 4 wherein said control means includes a resetable timer means for initiating said calibrating process at predetermined timed intervals, said timer means being reset when said calibrating process is completed.

6. A calibration system for automatically calibrating a plurality of electrical measuring systems of a gauging machine in sequence, each measuring system of the type having a gain circuit, a zero circuit and a combination circuit to obtain compensated electrical input signals, each of the measuring systems producing an electrical measurement in a predetermined range defined by upper and lower bounds, said calibration system comprising:

first and second reference means for providing first and second references corresponding to the lower and upper bounds, respectively, of the predetermined range of the measuring systems when calibrated, the uncalibrated measuring systems providing a plurality of first and second electrical input signals upon measuring said first and second reference means, respectively, the gauging machine including a drive means for positioning the measuring devices and the first reference means in operative relationship to obtain the first input signals and for positioning the second reference means and the measuring devices in operative relationship to obtain the second input signals,

control means for controlling the gauging machine, wherein said control means controls the drive means and is responsive to signals from the gauging machine indicating said operative relationships to control the calibrating process,

scanning means responsive to said control means for scanning the measuring systems to allow said control means to sequentially control the calibration process of each electrical measuring system, and

calibrating means responsive to said controller, said first and second input signals and said scanning means for sequentially adjusting said zero circuits and said gain circuits wherein the electrical measuring systems output compensated input signals corresponding to the lower bound and the upper bound in response to said first and second input signals, respectively.

7. The system as claimed in claim 6 wherein said calibrating means includes comparator means for comparing reference signals to corresponding compensated input signals and outputting corresponding adjustment signals corresponding to their respective difference therebetween.

8. The system as claimed in claim 7 wherein said calibrating means includes adjusting means for adjusting the zero and gain circuits in response to corresponding adjustment signals.

9. The system as claimed in claim 8 wherein said adjusting means includes zero adjusting means for adjusting the zero circuits in response to a plurality of first adjustment signals wherein the electrical measuring systems output compensated input signals corresponding to the lower bound.

10. The system as claimed in claim 9 wherein said adjusting means includes gain adjusting means for adjusting the gain of the gain circuits in response to a plurality of second adjustment signals wherein the electrical measuring systems output a corresponding plurality of compensated input signals corresponding to the upper bound.

11. The system as claimed in claim 10 wherein the upper and lower bounds and said corresponding input signals are of opposite polarity and wherein said calibration system includes a polarity detector means for detecting the polarity of said input signals to characterize said adjustment signals, said zero adjustment means being responsive to said polarity detector means.

12. The system as claimed in claim 11 wherein said control means includes a resettable timer means for initiating said calibrating process at predetermined timed intervals, said timer means being reset when said calibrating process is completed.

13. A calibration system for automatically calibrating a plurality of electrical measuring systems of a gauging machine in sequence, each measuring system of the type having a gain circuit, a zero circuit and a combination circuit to obtain compensated electrical input signals, each of the measuring systems producing an electrical measurement in a predetermined range defined by upper and lower bounds, said calibration system comprising:

first and second reference means for providing first and second references corresponding to the lower and upper bounds, respectively, of the predetermined range of the measuring system when calibrated, the uncalibrated measuring systems providing a plurality of first and second electrical input signals upon measuring said first and second reference means, respectively, the gauging machine including a drive means for positioning the measuring devices and the first reference means in operative relationship to obtain the first input signals and for positioning the second reference means and the measuring devices in operative relationship to obtain the second input signals,

third reference means for providing fixed and variable reference signals,

comparator means for comparing reference signals to corresponding compensated input signals and outputting corresponding adjustment signals corresponding to the differences therebetween,

zero adjustment means for adjusting the zero circuits in response to a plurality of first adjustment signals wherein the electrical measuring systems output a corresponding plurality of compensated input signals corresponding to the lower bound;

control means for controlling the gauging machine, wherein said control means controls the drive means and is responsive to signals from the gauging machine indicating said operative relationships to control the calibration process;

scanning means responsive to said control means for scanning the measuring systems to allow said control means to sequentially control the calibration process of each measuring system;

gain adjustment means for adjusting the gain of the gain circuits in response to a plurality of second adjustment signals wherein the electrical measuring systems output a corresponding plurality of compensated input signals corresponding to the upper bound.

14. The system as claimed in claim 13 wherein said control means includes a resettable timer means for initiating said calibration process at predetermined timed intervals, said timer means being reset when said calibrating process is completed.

15. The system as claimed in claim 13 or claim 14 wherein the upper and lower bounds are of opposite polarity and said corresponding input signals are of opposite polarity and wherein said calibration system includes a polarity detector means for detecting the polarity of said input signals to characterize said adjustment signals, said zero adjustment means being responsive to said polarity detector means.

16. The system as claimed in claim 15 wherein said third reference means includes switching means for switching one of a fixed reference signal and a variable reference signal to said comparator means.

17. A calibration system for calibrating an electrical measuring system, of the type having a gain circuit, a zero circuit and a combination circuit to obtain compensated electrical input signals, the measuring system producing an electrical measurement in a predetermined range defined by upper and lower bounds, said calibration system comprising:

first and second reference means for providing first and second references corresponding to the lower and upper bounds, respectively, of the predetermined range of the measuring system when calibrated, the uncalibrated measuring system providing first and second electrical input signals upon measuring said first and second references, respectively,

third reference means for providing fixed and variable reference signals,

comparator means for comparing reference signals to corresponding compensated input signals, and outputting corresponding adjustment signals corresponding to the difference therebetween, the comparator means comparing a fixed reference signal corresponding to said lower bound with the first input signal and outputting a first adjustment signal corresponding to the difference therebetween,

zero adjustment means for adjusting the zero circuit in response to selected adjustment signals including said first adjustment signal wherein the electrical measuring system outputs a second compensated input signal corresponding to the lower bound, said third reference signal corresponding to a third compensated input signal defined by the combined second input signal and a signal from the adjusted zero circuit, said comparator means comparing said variable reference signal with the third compensated input signal and outputting a second adjustment signal corresponding to the difference therebetween, said zero adjustment means readjusting the zero circuit in response to said second adjustment signal wherein the electrical measuring system outputs a fourth compensated input signal;

said comparator means comparing said fourth compensated input signal with a fixed reference signal corresponding to said upper bound and outputting a third adjustment signal corresponding to the difference therebetween, and

gain adjustment means for adjusting the gain circuit in response to said third adjustment signal wherein the electrical measuring system outputs a fifth compensated input signal corresponding to the upper bound.

18. The system as claimed in claim 17 wherein the upper and lower bounds are of opposite polarity and said corresponding input signals are of opposite polarity and wherein said calibration system includes a polarity detector means for detecting the polarity of said input signals to characterize said adjustment signals, said zero adjustment means being responsive to said polarity detector means.

19. The system as claimed in claim 17 or claim 18 wherein said third reference means includes a variable reference means for providing the variable reference signal, said variable reference signal corresponding to one-half the algebraic sum of said fixed reference signal corresponding to the upper bound and said third compensated input signal and wherein both of said fixed reference signals are equal in magnitude, said upper and lower bounds being equal in magnitude and opposite in polarity.

20. A method for calibrating an electrical measuring system of the type having a gain circuit for amplifying electrical input signals, a zero circuit and a combination circuit to obtain compensated electrical input signals, the measuring system producing an electrical measurement in a predetermined range defined by upper and lower bounds of opposite polarity, said method comprising the steps of:

sensing first and second references corresponding to the upper and lower bounds, respectively, to provide first and second electrical input signals, respectively, of opposite polarity to the electrical measuring system,

comparing reference signals corresponding to the lower and upper bounds with the corresponding compensated electrical input signals corresponding to the first and second references, respectively, to generate corresponding first and second adjusted signals corresponding to the differences therebetween, and

adjusting the zero and gain circuits in response to the first and second adjusted signals, respectively, wherein the electrical measuring system outputs compensated input signals corresponding to the lower and upper bounds, respectively.

21. Method as claimed in claim 20 wherein the sensing step includes the step of positioning a measuring device in operative relationship with the first and second references.

22. A method for calibrating a plurality of electrical measuring systems, each measuring system of the type having a gain circuit for amplifying electrical input signals, a zero circuit and a combination circuit to obtain compensated electrical input signals, each of the measuring systems producing an electrical measurement in a predetermined range defined by upper and lower bounds, said method comprising the steps of:

positioning the measuring devices in operative relationship with a first reference means corresponding to the lower bound,

sensing the first reference means to provide a plurality of first electrical input signals to the electrical measuring systems,

comparing a first reference signal corresponding to the lower bound with a first plurality of compensated electrical input signals to generate a corresponding plurality of first adjusted signals, corresponding to the differences therebetween,

adjusting the corresponding zero circuits in response to the first plurality of adjusted signals wherein the electrical measuring systems output a second plurality of compensated input signals corresponding to the lower bound,

positioning the measuring devices in operative relationship with a second reference means corresponding to the upper bound,

sensing the second reference means to provide a second plurality of electrical input signals to the electrical measuring systems,

comparing a second reference signal corresponding to the upper bound with compensated electrical input signals corresponding to the second reference means to generate a corresponding plurality of second adjusted signals corresponding to the differences therebetween, and

adjusting the gain circuits in response to the second plurality of adjusted signals wherein the electrical measuring systems output compensated input signals corresponding to the upper bound.