PROGRAMMABLE DISTANCE MEASURING INSTRUMENT

• US 3,865,305 A
• Filed: 12/27/1973
• Issued: 02/11/1975
• Est. Priority Date: 11/01/1971
• Status: Expired due to Term

• Current Assignee: Nu-Metrics Incorporated Longdale Industrial Park
• Original Assignee: Harry R. Sampey
• Inventors: Sampey, Harry R.
• Primary Examiner(s): Shaw, Gareth D.
• Assistant Examiner(s): Thesz, Jr., Joseph M.
• Application Number:
  US05/428,700
• Time in Patent Office: 411 Days
• Field of Search: 235/92DM,92DN,92PE,92V,92CC,92T 33/141E,141R,125M 324/171
• US Class Current: 377/24
• CPC Class Codes: G01C 22/02 by conversion into electric waveforms and subsequent integration, e.g. using tachometer generator G01C22/002, G01C22/004, G01C22/006 take precedence
• CPC Class Codes: H03M 1/00 Analogue/digital conversion; Digital/analogue conversion conversion of analogue values to or from differential modulation H03M3/00
• CPC Class Codes: H03M 1/48 Servo-type converters

Abstract

An instrument and method for digitally measuring distances or lengths in terms of any desired basic unit of distance measurement which is easily calibrated thereto by programmable switches and which is also capable of providing virtually unlimited measurement accuracy. Apparatus is disclosed for producing electrical '"'"''"'"''"'"''"'"'distance'"'"''"'"''"'"''"'"' pulses which each represent some arbitrary but approximately fixed increment of distance or length for which a totalized measurement is desired. These distance pulses are input to a programmable control circuit which produces a preselectable number N of clock pulses in response to each distance pulse. The preselectable number N of clock pulses is chosen to represent the magnitude of the arbitrary increment of distance or length in accordance with any desired basic unit of measurement. The gated N clock pulses, are then counted and accumulated to provide a digital data output representing the total measured distance or length which may include any desired number of the arbitrary increments. The instantaneous contents of the accumulator may be displayed for a direct readout of the measured distance in terms of the desired basic units of measurement and/or a digital output may be provided for conventional printing apparatus. The exemplary embodiment also includes circuits for temporarily holding the contents of the accumulator, circuits for resetting the counter circuits to a beginning zero contents and circuits for operating the instrument in a calibration mode wherein the number of distance pulses occurring during a premeasured distance interval can be obtained to facilitate calculation of the required preselectable program number N.

Claims

1. A variably programmable electronic distance measuring instrument for accumulating arbitrary distance increments in terms of any desired unit of distance measurement comprising:

a rotatable wheel having an unknown circumference dimension adapted for traversing distances, input means adapted to cooperate with said rotatable wheel for repetitively producing electrical distance pulses, each of said distance pulses representing an arbitrary unknown but relatively fixed increment of distance or length traversed by said wheel under constant measurement conditions such as wheel speed, variably adjustable programmable control means connected to said input means for producing a variable preselectable number of electrical clock pulses in response to each occurrence of one of said distance pulses, said preselectable number being variably selectable to represent the magnitude of said increment of arbitrary unknown distance or length in accordance with any desired arbitrary basic unit of distance measurement, and accumulator and display means connected to receive and accumulate said clock pulses from said programmable control means whereby digital data is provided and visibly displayed which data represents a total measured distance or length traversed by said wheel comprising a plurality of said arbitrary unknown increments which is directly displayed in terms of said desired basic unit of distance measurement, said variably adjustable programmable control means comprising;

clock means for producing clock pulses at a repetition rate that is high compared to the maximum expected rePetition rate of said distance pulses, digital counter means connected to count said clock pulses, variably adjustable program means for presetting digital data therein representing said variably preselectable number, start/stop control means connected for enabling said digital counter means in response to each received distance pulse and for resetting and disabling said digital counter means in response to detected coincidence between the preset data in said program means and the instantaneous contents of said digital counter means, and clock means connected to said clock means and to said start/stop control means for passing clock pulses therethrough only while said digital counter means is enabled thereby passing said preselectable number of clock pulses.

2. A programmable electronic distance measuring instrument as in claim 1 wherein said input means comprises:

a plurality of sensible index marks disposed at angular intervals about said wheel, which wheel is adapted for travel over a distance or length to be measured, sensor means mounted near said wheel for sensing the passage of said index marks thereby during the travel of said wheel and for producing said distance pulses in response thereto.

3. A programmable electronic distance measuring instrument as in claim 2 further comprising:

signal processing means connected to an output of said sensor for amplifying, noise filterning and pulse shaping said distance pulses to provide a relatively uniformly dimensioned distance pulses for utilization by said programmable control means.

4. A programmable electronic distance measuring instrument as in claim 1 wherein:

said program means comprises a plurality of presettable switches individually connected to predetermined outputs of said digital counter means, and said start/stop control means comprises;

bistable means connected to be triggered to a first state by said distance pulses and to simultaneously enable said digital counter means and said clock gate means while in said first state, and coincidence gate means connected to said presettable switches for producing a reset output when said coincidence occurs and for triggering said bistable means to its second state in response thereto whereby both said digital counter means and said clock gate means are disabled.

5. A programmable electronic distance measuring instrument as in claim 1 further including:

hold switch means for temporarily preventing further change in the contents of said accumulator means by preventing further input thereto.

6. A programmable electronic distance measuring instrument as in claim 1 wherein said accumulator means comprises:

first digital counting means for counting a predetermined number of said clock pulses corresponding to one of said desired basic units of measurement and for producing an output pulse in response thereto, second counting means connected to receive said output pulses corresponding to said desired basic unit of measurement for counting and storing an accumulated number of such pulses, and display means connected to display the contents of said second counting means.

7. A programmable electronic distance measuring instrument as in claim 6 wherein said first digital counting means comprises a plurality of cascaded stages connected to cyclically count X pulses and provide one carryout pulse for each X pulses counted as said output pulse whereby each clock pulse is representative of 1/X of said desired basic unit of measurement.

8. A programmable electronic distance measuring instrument as in claim 6 wherein said second counting means comprises:

a units counter stage for directly counting and accumulating said output pulses whereby the contents of the units counter stage directly represents the currently measured number of said basic units of measurement, carryover gate detectors connected to detect a predetermined contents of said basic counteR stage representing a predetermined multiple number of said basic units of measurement and for producing a carry pulse in response thereto, and a further counter stage for counting and accumulating said carry pulses whereby the further counter stage contents directly represents the measured number of said predetermined multiples.

9. A variably programmable electronic distance measuring instrument for accumulating arbitrary distance increments in terms of any desired unit of distance measurement comprising:

a rotatable wheel having an unknown circumference dimension adapted for traversing distances, input means adapted to cooperate with said rotatable wheel for reptitively producing electrical distance pulses, each of said distance pulses representing an arbitrary unknown but relatively fixed increment of distance or length traversed by said wheel under constant measurement conditions such as wheel speed, variably adjustable programmable control means connected to said input means for producing a variable preselectable number of electrical clock pulses in response to each occurrence of one of said distance pulses, said preselectable number being variably selectable to represent the magnitude of said increment of arbitrary unknown distance or length in accordance with any desired arbitrary basic unit of distance measurement, accumulator and display means connected to receive and accumulate said clock pulses from said programmable control means whereby digital data is provided and visibly displayed which data represents a total measured distance or length traversed by said wheel comprising a plurality of said arbitrary unknown increments which is directly displayed in terms of said desired basic unit of distance measurement, and calibrate switch means for effectively bypassing said programmable control means and for effectively passing said distance pulses directly to said accumulator means in a calibrate mode whereby the number of distance pulses occurring over a known distance may be directly obtained for use in determining the preselectable number necessary to result in distance measurement calibrated for any desired basic measurement unit.

10. A method for digitally measuring and displaying distances traversed by a wheeled vehicle in a desired unit of measure which may be adjustably altered to work with arbitrary vehicle wheel sizes and other desired units of measure, said method comprising:

generating electrical distance pulses as a function of distance actually traversed by said vehicle, each of said distance pulses representing substantially equal increments of traversed distance, the actual value of said increments being arbitrary to the extent it depends upon particular vehicle parameters such as wheel sizes, electrically multiplying the number of said distance pulses by a factor N which is adjustable in arbitrary small digital increments over a broad range, adjusting the factor N beforehand to produce output pulses which are each representative of a predetermined fraction of the desired unit of measure as a function of the magnitude of said arbitrary but substantially equal increments of traversed distance represented by each of said distance pulses, electrically dividing the number of said output pulses by said predetermined fraction to produce further pulses representative of distance traversed by said vehicle according to said desired unit of measure, automatically counting the number of said further pulses, and displaying the accumulated result of said counting step as the distance traversed by said vehicle in terms of said desired unit of measure, said adjusting step comprising;

counting the number of distance pulses produced by the vehicle'"'"''"'"'s traverse of a distance X known in terms of said desired unit of measure, determining the average number of said predetermined fractions of the desired unit of measure per distance pulse, and adjusting N to substantially equal saiD average number.

11. A method as in claim 10 wherein said generating step comprises:

applying machine-sensible index marks at regular intervals about a non-driven wheel of said vehicle, sensing the passage of said index marks past a sensor fixedly mounted with respect to said non-driven wheel and producing an electrical distance pulse in response to each such sensed passage of an index mark.

12. A method as in claim 10 wherein said electrically multiplying step comprises gating N clock pulses in response to each distance pulse, said clock pulses occurring at a rate in excess of N times the highest expected rate of said distance pulses.

13. A method as in claim 10 wherein said last-mentioned counting step is performed while said vehicle is traveling at approximately the same speed that is to be utilized during an actual measurement.