GB2161262A - Digital instrumentation apparatus for the linear air-track - Google Patents

Digital instrumentation apparatus for the linear air-track Download PDF

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Publication number
GB2161262A
GB2161262A GB08417133A GB8417133A GB2161262A GB 2161262 A GB2161262 A GB 2161262A GB 08417133 A GB08417133 A GB 08417133A GB 8417133 A GB8417133 A GB 8417133A GB 2161262 A GB2161262 A GB 2161262A
Authority
GB
United Kingdom
Prior art keywords
digital
array
atv
track
detector
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB08417133A
Other versions
GB8417133D0 (en
Inventor
Dr D E Hookes
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
CO OPERATIVE TECHNOLOGY Ltd
HOOKES DAVID EDWARD
Original Assignee
CO OPERATIVE TECHNOLOGY Ltd
HOOKES DAVID EDWARD
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by CO OPERATIVE TECHNOLOGY Ltd, HOOKES DAVID EDWARD filed Critical CO OPERATIVE TECHNOLOGY Ltd
Priority to GB08417133A priority Critical patent/GB2161262A/en
Publication of GB8417133D0 publication Critical patent/GB8417133D0/en
Publication of GB2161262A publication Critical patent/GB2161262A/en
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/36—Forming the light into pulses
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
    • G01P3/42—Devices characterised by the use of electric or magnetic means
    • G01P3/50—Devices characterised by the use of electric or magnetic means for measuring linear speed
    • G01P3/54—Devices characterised by the use of electric or magnetic means for measuring linear speed by measuring frequency of generated current or voltage

Abstract

Digital instrumentation apparatus for a linear air-track, for measuring the position-time curves of several air-track vehicles (ATVS) simultaneously, comprises a transmission or reflection linear aperture array TA which can be rigidly attached to an ATV, a narrow beam source S of electromagnetic radiation, and a detector D for this beam. Digital pulse-timing circuitry and an interface for linking to a memory associated with a digital computer are also provided. The motion of the array across the beam causes the beam to fall intermittently on the detector which is, therefore, caused to emit voltage or current pulses. The digital circuitry measures the sequences of time interval between successive pulses and stores them in the digital memory. These intervals, together with the accurately known set of repeat spacings of the array, allows the position-time curves for an ATV to be deduced and displayed by a digital computer. Further processing of the data is also possible. <IMAGE>

Description

SPECIFICATION Digital instrumentation apparatus for the linear air-track This invention relates to the digital instrumentation of the linear air-track, used mainly as a teaching tool. It is used both to demonstrate different types of linear motion as well as to test the laws of Dynamics and their consequences, such as the conservation of linear momentum and the conservation of energy. Various types of instrumentation are available to measure the position or the speed of the air-track vehicles, hereafter referred to as ATVs. Such methods include stroboscopic photography and timer-counters coupled to photocells. One approach even uses a microprocessor to calculate up to eight values of the speed of the ATVs.None to date give a measurement of the position of an ATV as a function of time with sufficient resolution to allow smooth curves of the same to be drawn during, for example, a soft collision between two ATVs.
According to the present invention apparatus is provided to measure the position of one or several moving ATVs as a function of time with a displacement resolution of a fraction of a millimetre, typically 0.5mm. The displacement-time data are logged into the memory associated with a digital computer. The position-time curves can subsequently be displayed, for example on a VDU, or obtained as hard-copy. The data can further be processed to demonstrate the properties of different types of motion and carry out tests of physical laws.
The present invention provides digital instrumentation apparatus for the linear air-track for measuring the position- time curves of an air-track vehicle (ATV). The instrumentation preferably comprises: 1. A Transmission or Reflection linear aperture array which can be rigidly attached to an ATV.
(Hereafter sometimes referred to simply as arrays).
2. A narrow beam source of electromagnetic radiation, typically an optical source.
3. A detector for this beam.
4. Digital pulse-timing circuitry, and an interface for linking to a memory associated with a digital computer.
A specific embodiment of the apparatus is shown by way of example with reference to the accompanying drawings.
Figure 1(a) shows, in plan view, the transmission array with alternate opaque and transparent regions, mounted on an ATV. Also shown is the narrow beam source of electromagnetic radiation, hereafter referred to as the beam, and its detector.
Figure 1(b) shows a reflection array mounted on an ATV with its narrow beam source and detector.
Figure 2 shows, in block diagram form, the digital pulse-timing circuitry and interface and their connections to the memory and the digital computer.
Referring to Figure 1, the motion of the transmission or reflection array attached to the moving ve hicle causes the beam to fall intermittently on its detector. This causes the output of the detector to be intermittent, that is, the motion of the vehicle produces a sequence of voltage or current pulses from the detector. The time between two consecutive pulses is therefore the time for the corresponding repeat spacing of the array to cross the beam.
Referring to Figure 2, the digital pulse-timing circuitry measures accurately the sequence of times between consecutive pulses, and the interface circuitry enables them to be logged into the memory associated with the computer, either under software control or by direct memory access (DMA).
The pulse count is maintained either by software or a hardware counter. The pulse count allows the total movement of an ATV to be determined from the set of repeat spacings of the array which are accurately known.
The form of the pulse-timing data allows a direct computation of the average speed of the ATV over a displacement interval equal to the particular repeat spacing of the array. Thus the speed-time curves can be readily obtained.
As is also shown in Figure 2 the circuitry has several input channels for data pulses, thus allowing the motion of several ATVs to be logged. It also posesses a real-time clock to enable a common time origin for the motion of several vehicles to be established.
Additional measurements, using, say, a metre rule, of the separation of the several narrow beams enables a common origin for the position of several vehicles to be established.
As can be inferred from Figure 1, this method in no way interfers with the motion of the vehicle so as to alter its dynamics, other than by increasing the mass of a ATV by that of the material making up the array and its holder.
1. Digital instrumentation apparatus for the linear air-track for measuring the position-time curves of an air-track vehicle (ATV) comprising a narrow beam source of electromagnetic radiation, a linear aperture array that can be rigidly attached to an air-track vehicle, said narrow beam being incident on said array, a detector for said narrow beam, and digital circuitry to process data from said de vector.
2. Digital intrumentation apparatus according to Claim 1, wherein the linear aperture array is either a transmission or reflection aperture array.
3. Digital instrumentation apparatus according to Claim 2 wherein the transmission aperture array comprises adjacent regions that respectively occlude and transmit the narrow beam, the set of spacings between adjacent equivalent regions being accurately known.
4. Digital instrumentation apparatus according to Claim 2 wherein the reflection aperture array consists of regions that respectively absorb and reflect the narrow beam, the set of spacings between adjacent equivalent regions being accurately
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Digital instrumentation apparatus for the linear air-track This invention relates to the digital instrumentation of the linear air-track, used mainly as a teaching tool. It is used both to demonstrate different types of linear motion as well as to test the laws of Dynamics and their consequences, such as the conservation of linear momentum and the conservation of energy. Various types of instrumentation are available to measure the position or the speed of the air-track vehicles, hereafter referred to as ATVs. Such methods include stroboscopic photography and timer-counters coupled to photocells. One approach even uses a microprocessor to calculate up to eight values of the speed of the ATVs.None to date give a measurement of the position of an ATV as a function of time with sufficient resolution to allow smooth curves of the same to be drawn during, for example, a soft collision between two ATVs. According to the present invention apparatus is provided to measure the position of one or several moving ATVs as a function of time with a displacement resolution of a fraction of a millimetre, typically 0.5mm. The displacement-time data are logged into the memory associated with a digital computer. The position-time curves can subsequently be displayed, for example on a VDU, or obtained as hard-copy. The data can further be processed to demonstrate the properties of different types of motion and carry out tests of physical laws. The present invention provides digital instrumentation apparatus for the linear air-track for measuring the position- time curves of an air-track vehicle (ATV). The instrumentation preferably comprises: 1. A Transmission or Reflection linear aperture array which can be rigidly attached to an ATV. (Hereafter sometimes referred to simply as arrays). 2. A narrow beam source of electromagnetic radiation, typically an optical source. 3. A detector for this beam. 4. Digital pulse-timing circuitry, and an interface for linking to a memory associated with a digital computer. A specific embodiment of the apparatus is shown by way of example with reference to the accompanying drawings. Figure 1(a) shows, in plan view, the transmission array with alternate opaque and transparent regions, mounted on an ATV. Also shown is the narrow beam source of electromagnetic radiation, hereafter referred to as the beam, and its detector. Figure 1(b) shows a reflection array mounted on an ATV with its narrow beam source and detector. Figure 2 shows, in block diagram form, the digital pulse-timing circuitry and interface and their connections to the memory and the digital computer. Referring to Figure 1, the motion of the transmission or reflection array attached to the moving ve hicle causes the beam to fall intermittently on its detector. This causes the output of the detector to be intermittent, that is, the motion of the vehicle produces a sequence of voltage or current pulses from the detector. The time between two consecutive pulses is therefore the time for the corresponding repeat spacing of the array to cross the beam. Referring to Figure 2, the digital pulse-timing circuitry measures accurately the sequence of times between consecutive pulses, and the interface circuitry enables them to be logged into the memory associated with the computer, either under software control or by direct memory access (DMA). The pulse count is maintained either by software or a hardware counter. The pulse count allows the total movement of an ATV to be determined from the set of repeat spacings of the array which are accurately known. The form of the pulse-timing data allows a direct computation of the average speed of the ATV over a displacement interval equal to the particular repeat spacing of the array. Thus the speed-time curves can be readily obtained. As is also shown in Figure 2 the circuitry has several input channels for data pulses, thus allowing the motion of several ATVs to be logged. It also posesses a real-time clock to enable a common time origin for the motion of several vehicles to be established. Additional measurements, using, say, a metre rule, of the separation of the several narrow beams enables a common origin for the position of several vehicles to be established. As can be inferred from Figure 1, this method in no way interfers with the motion of the vehicle so as to alter its dynamics, other than by increasing the mass of a ATV by that of the material making up the array and its holder. CLAIMS
1. Digital instrumentation apparatus for the linear air-track for measuring the position-time curves of an air-track vehicle (ATV) comprising a narrow beam source of electromagnetic radiation, a linear aperture array that can be rigidly attached to an air-track vehicle, said narrow beam being incident on said array, a detector for said narrow beam, and digital circuitry to process data from said de vector.
2. Digital intrumentation apparatus according to Claim 1, wherein the linear aperture array is either a transmission or reflection aperture array.
3. Digital instrumentation apparatus according to Claim 2 wherein the transmission aperture array comprises adjacent regions that respectively occlude and transmit the narrow beam, the set of spacings between adjacent equivalent regions being accurately known.
4. Digital instrumentation apparatus according to Claim 2 wherein the reflection aperture array consists of regions that respectively absorb and reflect the narrow beam, the set of spacings between adjacent equivalent regions being accurately known.
5. Digital instrumentation apparatus according to Claims 3 and 4 wherein the spacings are such as to allow a fine resolution of the vehicle displacements, typically better than 1 millimetre.
6. Digital instrumentation apparatus according to any preceding Claim wherein the motion of the array attached to the moving ATV causes the narrow beam to fall intermittently on the detector which causes it to give out pulses of voltage or current.
7. Digital instrumentation apparatus according to Claim 6 wherein the time intervals between successive pulses from the detector are measured by the digital circuitry and a means is provided to store them in a digital memory device.
8. Digital instrumentation apparatus according to any preceding Claim wherein the digital circuitry has several input channels thereby allowing the motion of a plurality of ATVs to be determined.
9. Digital instrumentation apparatus for the linear air-track substantially as herein described with reference to the accompanying drawings.
GB08417133A 1984-07-05 1984-07-05 Digital instrumentation apparatus for the linear air-track Withdrawn GB2161262A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB08417133A GB2161262A (en) 1984-07-05 1984-07-05 Digital instrumentation apparatus for the linear air-track

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB08417133A GB2161262A (en) 1984-07-05 1984-07-05 Digital instrumentation apparatus for the linear air-track

Publications (2)

Publication Number Publication Date
GB8417133D0 GB8417133D0 (en) 1984-08-08
GB2161262A true GB2161262A (en) 1986-01-08

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3601939A1 (en) * 1986-01-23 1987-07-30 Licentia Gmbh Method for measuring a delay line for radio-frequency waves
GB2340320A (en) * 1998-07-29 2000-02-16 Ball Racing Developments Limit Movement measuring device; indicating the degree of vehicle braking

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB946140A (en) * 1961-05-04 1964-01-08 Ford Motor Co Improvements in or relating to torquemeters
GB971504A (en) * 1960-02-05 1964-09-30 Emi Ltd Improvements relating to displacement measuring apparatus employing diffraction gratings
GB1228277A (en) * 1968-04-26 1971-04-15
GB1294841A (en) * 1969-01-21 1972-11-01 Information Storage Systems
GB1353470A (en) * 1970-10-19 1974-05-15 Post D Position measuring apparatus utilizing moire fringe multiplication
GB2046896A (en) * 1979-04-11 1980-11-19 Marconi Co Ltd Apparatus for testing the braking efficiency of industrial machines
GB2067283A (en) * 1980-01-10 1981-07-22 Gamon Eng Co Ltd V C Determining relative movement
GB1602178A (en) * 1977-04-20 1981-11-11 Marconi Co Ltd Apparatus for testing the braking of a moving machine part
GB2093180A (en) * 1981-02-17 1982-08-25 Pradhan Sharad Ganesh System for Determining Distance Velocity and Acceleration
GB2095399A (en) * 1981-03-24 1982-09-29 Mitutoyo Mfg Co Ltd Photoelectrical displacement-measuring device

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB971504A (en) * 1960-02-05 1964-09-30 Emi Ltd Improvements relating to displacement measuring apparatus employing diffraction gratings
GB946140A (en) * 1961-05-04 1964-01-08 Ford Motor Co Improvements in or relating to torquemeters
GB1228277A (en) * 1968-04-26 1971-04-15
GB1294841A (en) * 1969-01-21 1972-11-01 Information Storage Systems
GB1353470A (en) * 1970-10-19 1974-05-15 Post D Position measuring apparatus utilizing moire fringe multiplication
GB1602178A (en) * 1977-04-20 1981-11-11 Marconi Co Ltd Apparatus for testing the braking of a moving machine part
GB2046896A (en) * 1979-04-11 1980-11-19 Marconi Co Ltd Apparatus for testing the braking efficiency of industrial machines
GB2067283A (en) * 1980-01-10 1981-07-22 Gamon Eng Co Ltd V C Determining relative movement
GB2093180A (en) * 1981-02-17 1982-08-25 Pradhan Sharad Ganesh System for Determining Distance Velocity and Acceleration
GB2095399A (en) * 1981-03-24 1982-09-29 Mitutoyo Mfg Co Ltd Photoelectrical displacement-measuring device

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3601939A1 (en) * 1986-01-23 1987-07-30 Licentia Gmbh Method for measuring a delay line for radio-frequency waves
GB2340320A (en) * 1998-07-29 2000-02-16 Ball Racing Developments Limit Movement measuring device; indicating the degree of vehicle braking
GB2340320B (en) * 1998-07-29 2003-04-30 Ball Racing Developments Ltd Indicating means

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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)