MEASUREMENT OF VELOCITY OF A BODY

• US 3,804,517 A
• Filed: 05/01/1972
• Issued: 04/16/1974
• Est. Priority Date: 05/04/1971
• Status: Expired due to Term

• Current Assignee: Heini Meyr, Rudolf Kuhne
• Original Assignee: Heini Meyr, Rudolf Kuhne
• Inventors: Meyr, Heini, Kuhne, Rudolf
• Primary Examiner(s): Smith, Alfred E.
• Assistant Examiner(s): Hille, Rolf
• Application Number:
  US05/249,084
• Time in Patent Office: 715 Days
• Field of Search: 324/175,160 356/28 235/150.34
• US Class Current: 356/28
• CPC Class Codes: G01P 3/803 in devices of the type to be classified in G01P3/66
• CPC Class Codes: G01P 3/806 in devices of the type to be classified in G01P3/68

Abstract

An apparatus for a moving body and a method for measuring the velocity of that body over a surface arranged parallel thereto and which has local irregular features therein wherein two areas of the surface directly therebeneath are illuminated during movement of the body and optical reflection of the surface areas is received by two photo-electric converters, which are spaced from one another on the moving body and in the direction of motion of the moving body, and which produce two similar electrical signal sequences of the character of noise,but time delayed one with respect to the other. Both signals are sampled, the samples obtained from the leading surface area in the direction of motion is delayed by a controllable amount and thereafter multiplied by the samples obtained from the other surface area. A mean time value is produced from the result of this multiplication and the delay is regulated in such a manner that the delayed and the other signal coincide in time, and the velocity is ascertained as the quotient from the spacing of the two areas and the regulated delay.

Claims

1. A method for measuring the speed of a body moving parallel to a surface that has local irregularities, comprising scanning the surface at a first and second area thereof and thereby producing a first and a second signal corresponding to the local irregularities of said first and second area respectively, said first and second areas moving together with said body, and said first area preceding the second area by a predetermined distance in the direction of movement of said body;

periodically sampling said first and second signals, thereby oBtaining first and second samples respectively;

delaying said first samples by a constant whole number of sampling periods;

multiplying each delayed first sample by the simultaneously appearing second sample, thereby providing a sequence of sample products;

continuously deriving an average value of said sequence of sample products;

regulating the period of sampling so that said average value will become maximum; and

dividing said predetermined distance by the product of said constant whole number and the period of said periodic sampling to provide the speed of the body.

2. A method for measuring the speed of a body moving parallel to a surface that has local irregularities, comprising scanning the surface at a first and second area thereof and thereby producing a first and a second signal corresponding to the local irregularities of said first and second area respectively, said first and second areas moving together with said body, said first area preceding the second area by a predetermined distance in the direction of movement of said body;

periodically sampling said first and second signals, thereby obtaining first and second samples respectively;

delaying said first samples by a first constant whole number of sampling periods and by a second constant whole number of sampling periods, thereby obtaining first and second delayed samples, said second number being higher than said first number;

multiplying each of said first delayed samples and each of said second delayed samples with the simultaneously appearing second sample thereby providing a first and a second sequence of sample products respectively;

continuously deriving a first average value of said first sequence of sample products, and continuously deriving a second average value of said second sequence of sample products;

continuously deriving the difference between said first and second values;

regulating the period of sampling so that said difference will become zero; and

dividing said predetermined distance by the product of the mean value of said first and second constant whole numbers and the period of said periodical sampling to provide the speed of the body.

3. A device for measuring the speed of a body moving parallel to a surface that has local irregularities, comprising scanning means fixed to said body and having a first and a second output delivering a first and a second signal corresponding to the local irregularities of a first and second area respectively of said surface, the first area preceding the second area by a predetermined distance in the direction of movement of said body;

sampling means having a first and a second input connected to said first and second outputs of said scanning means respectively, and having a first and a second output delivering first and second samples derived by periodically sampling said first and second signals respectively;

a shift register having an input connected to the first output of said sampling means and having an output delivering signals derived from said first samples by delaying them by a constant whole number of sampling periods;

a multiplier having two inputs, one connected to the second output of said sampling means and the other connected to the output of said shift register, and having an output;

a low pass filter having an input connected to the output of said multiplier and having an output;

a control circuit having an input connected to the output of said low pass filter, said control circuit connected to deliver periodic control pulses to said sampling means, said shift register and said multiplier, the frequency of said control pulses being so regulated that the value of the output signal of the low pass filter becomes a maximum; and

indicating means connected to said control circuit to receive said control pulses and responsive to the frequency thereof and calibrated in units of speed.

4. A device as set forth in claim 3, wherein said lOw pass filter is a pulsed filter for discrete samples and is connected for control by said control pulses.

5. A device as set forth in claim 3, wherein said sampling means at its first and second outputs are adapted to deliver coded samples derived by periodically sampling and coding said first and second signals respectively, and said shift register, multiplier and low pass filter are adapted to shift, multiply and filter coded signals.

6. A device as set forth in claim 3 wherein light pulse generating means for illuminating the first and second areas of the surface are included in said scanning means, said light pulse generating means being connected to said control circuit for control by said control pulses.

7. A device for measuring the speed of a body moving parallel to a surface that has local irregularities, comprising scanning means fixed to said body and having a first and a second output delivering a first and a second signal corresponding to the local irregularities of a first and a second area respectively of the surface, the first area preceding the second area by a predetermined distance in the direction of movement of said body;

sampling means having a first and a second input connected to said first and second output of said scanning means respectively, and having a first and a second output delivering first and second samples derived by periodically scanning said first and second signals respectively;

a shift register having a plurality of stages and having an input connected to the first output of said sampling means and having a first output at its penultimate stage and a second output at its last stage;

a first multiplier having a first input connected to the first output of said shift register, a second input connected to the second output of said sampling means and an output;

a second multiplier having a first input connected to the second output of said sampling means, a second input connected to the second output of said shift register and an output;

two low pass filters each having an input connected to the output of one of said first and second multipliers respectively and each having an output;

a subtraction circuit having two inputs each connected to the output of one of said two low pass filters and an output;

a control circuit having an output connected to the output of said substaction circuit, said control circuit connected to deliver periodic control pulses to said first and second sampling means, said shift register, and said first and second multipliers, the frequency of said control pulses being so regulated that the output signal of said substaction circuit becomes zero; and

indicating means connected to said control circuit to receive said control pulses and responsive to the frequency thereof and calibrated in units of speed.

8. A device as set forth in claim 7, wherein each of said low pass filters is a pulsed filter for discrete samples and is connected for control by said control pulses.

9. A device as set forth in claim 7, wherein said sampling means at its first and second outputs are adapted to deliver coded samples derived by periodically sampling and coding said first and second signals respectively, and said shift register, multipliers and low pass filter are adapted to shift, multiply and filter coded signals.

10. A device as set forth in claim 7, wherein light pulse generating means for illuminating the first and second areas of the surface are included in said scanning means, said light pulse generating means being connected to said control circuit for control by said control pulses.

11. A device for measuring the speed of a body moving parallel to a surface that has local irregularities, comprising scanning means fixed to said body and having a first and a second output delivering a first and a second signal corresponding to the local irregularities of a first and second area respectively of the surface, the first area preceding the second area by a predetermined dIstance in the direction of movement of said body;

sampling means having a first and a second input connected to said first and second output of said scanning means respectively and having a first and a second output delivering first and second samples derived by periodically sampling said first and second signals respectively;

a shift register having an input connected to the first output of said sampling means and having an output connectable to one of a plurality of consecutive register stages which is selected by a control signal;

a multiplier having two inputs, one connected to the second output of said sampling means and the other connected to the output of the shift register and having an output;

a low pass filter having an input connected to the output of the multiplier and having an output;

control means having an input connected to the output of said low pass filter, said control means connected to deliver periodic control pulses to said sampling means, said shift register and said multiplier and connected to deliver said control signal to select said one of said plurality of register stages, said control signal being so regulated that the value of the output signal of the low pass filter becomes a maximum; and

indicating means connected to said control circuit and responsive to said control signal and calibrated in units of speed.