Method and apparatus for measuring the velocity of moved objects or the like

• US 4,527,894 A
• Filed: 09/27/1982
• Issued: 07/09/1985
• Est. Priority Date: 12/17/1981
• Status: Expired due to Term

• Current Assignee: Multanova AG (Jenoptik AG)
• Original Assignee: Zellweger Uster Ltd.
• Inventors: Hauser, Peter, Mira, Silvio, Goede, Simon
• Primary Examiner(s): BUCZINSKI, STEPHEN C
• Application Number:
  US06/424,920
• Time in Patent Office: 1,016 Days
• Field of Search: 356/28, 356/5
• US Class Current: 356/28
• CPC Class Codes: G01S 17/58 Velocity or trajectory determination systems; Sense-of-movement determination systems

Abstract

The invention relates to a method and apparatus for measuring the velocity of a moving object. Measuring beams composed of sequences of optical pulses are directed towards the object which is to be measured and follow such object. Based upon transit time measurements of reflected pulses there are formed distance values and distance difference values. While taking into account the time interval of the pulse sequence there are computed velocity measuring values and velocity values computed from homogeneous groups of values are displayed as reliable velocity values. By means of a measuring beam deflection system there are directed measuring beams into defined solid angle sectors towards the object which is to be measured, and reliable velocity measuring values computed from homogeneous groups of measuring values from the measuring channels correlated to the individual solid angle sectors are displayed as binding or valid velocity measuring values if there is present a confirmation of the value from further solid angle sectors.

Claims

1. A method of measuring the velocity of a moving object by means of pulsed optical radiation, comprising the steps of:

forming at least one measuring beam from a sequence of optical pulses;

directing said at least one measuring beam towards the object whose velocity is to be measured;

determining the transit times of the at least one measuring beam to the object and its reflection at the object back to a site where the at least one measuring beam was transmitted;

forming distance values from the determined transit times and distance differences from the distance values;

dividing the distance differences by related time spans in order to form velocity values of the moving object to be measured;

selecting at least one of said time spans during which substantially constant values are formed of said velocity of the moving object and thus determining a reliable velocity value; and

displaying said reliable velocity value.

2. The method as defined in claim 1, wherein:

said step of forming said at least one measuring beam entails the step of forming said at least one measuring beam from a sequence of substantially uniformly spaced optical pulses;

selecting at least one sequence of consecutive ones of said distance values and/or said distance differences and/or said velocity values in respect of their homogeneity; and

computing reliable velocity values only upon fulfillment of predetermined homogeneity criteria.

3. The method as defined in claim 2, further including the steps of:

dividing the sum of said at least one sequence of homogeneous distance difference values by the sum of related time spans of relevant pulse sequences in order to compute said reliable velocity value.

4. The method as defined in claim 3, wherein:

said predetermined homogeneity criteria constitutes the fulfilled condition that all values of said at least one sequence of distance differences are located within a fixed absolute or relative tolerance range.

5. The method as defined in claim 2, further including the steps of:

selecting at least one sequence of a predetermined number of consecutive ones of said formed distance values which fall within a predetermined tolerance range and thus constitute homogeneous distance values;

forming from said selected at least one sequence of consecutive distance values at least one sequence of a predetermined number of consecutive distance differences which fall within a predetermined tolerance range and thus constitute homogeneous distance differences; and

dividing the sum of said at least one sequence of homogeneous distance differences by the sum of related time spans of relevant pulse sequences in order to determine said reliable velocity value.

8. The method as defined in claim 1, wherein:

said step of forming said at least one measuring beam entails the step of forming a predetermined number of spatially separate measuring beams each one of which is formed from said sequence of optical pulses;

the measuring beams formed from said sequence of optical pulses are produced by a single light source;

determining said reliable velocity value for different ones of said predetermined number of spatially separate measuring beams; and

comparing said reliable velocity values associated with said different predetermined number of spatially separate measuring beams in order to determine reliable velocity values which have a predetermined interrelationship, each of which is associated with a different one of said predetermined number of spatially separate measuring beams and which thus constitute binding velocity values.

6. A method of measuring the velocity of a movable object by means of pulsed optical radiation, comprising the steps of:

forming measuring beams from a sequence of optical pulses;

directing the measuring beams towards the object whose velocity is to be measured;

determining the transit times of the measuring beams to the object and their reflection at the object back to a site where the measuring beams were transmitted;

forming distance values from the determined transit times and distance differences from the distance values;

dividing the distance differences by related time spans in order to form velocity values for the object to be measured;

displaying the formed velocity values;

transmitting to the object to be measured measuring beams over at least two different paths;

separately detecting the transit times of the pulses of such measuring beams along the aforementioned paths;

forming from these transit times the distance measuring values and from these distance measuring values distance differences;

computing reliable velocity values from these distance differences; and

displaying the velocity values only then as binding velocity values when there have been fulfilled predetermined criteria by velocity values emanating from different directions.

7. The method as defined in claim 6, further including the steps of:

comparing with one another the velocity values emanating from different directions; and

only then performing and displaying a binding measuring value when the difference of the velocity values emanating from different directions does not exceed a predetermined tolerance range.

9. A method of measuring the velocity of a moving object by means of pulsed optical radiation, comprising the steps of:

generating from a single light source a plurality of discretely directed light pulses defining a plurality of measuring beams which are targeted towards a predetermined object whose velocity is to be measured;

forming from transit times of such pulses to the object and reflection thereof at the object back to a site where the measuring beams were transmitted distance values and from said distance values forming distance differences;

dividing the distance differences by related time spans in order to form velocity values for the object whose velocity is to be measured; and

selecting at least one time span during which substantially constant values are formed of said velocity of said moving object.

10. An apparatus for measuring the velocity of a moving object by means of pulsed optical radiation, comprising:

a pulsed light source for furnishing pulsed optical radiation;

a transmitter optical system for transmitting the pulsed optical radiation towards the object to be measured;

said transmitter optical system having an optical axis;

a transparent disk rotatably arranged with respect to said optical axis between the pulsed light source and the transmitter optical system;

said transparent disk being inclined with respect to said optical axis;

said rotatably arranged transparent disk deflecting said measuring beams emanating from the light source into a predetermined number of different solid angle sectors each of which generates a differently located light spot at said moving object; and

circuit means controlling said pulsed light source and evaluating pulsed radiation reflected from said moving opbject as well as determining and storing velocity values of said moving object for each one of said predetermined number of different solid angle sectors.

11. The apparatus as defined in claim 10, wherein:

said circuit means include a transmitter trigger and drive regulation circuit for the synchronization of transmitter trigger pulse sequences and for the rotation of the transparent disk; and

said transmitter trigger and drive regulation circuit outputting transmitter trigger signals at a transmitter trigger frequency which is in a defined relationship to the rotational speed of the rotatable transparent disk.

12. An apparatus for measuring the velocity of a moving object by means of pulsed optical radiation, comprising:

a pulsed light source for furnishing pulsed optical radiation;

a transmitter optical system for transmitting the pulsed optical radiation towards the object to be measured;

said transmitter optical system having an optical axis;

a transparent disk rotatably arranged with respect to said optical axis between the pulsed light source and the transmitter optical system;

said transparent disk being inclined with respect to said optical axis;

said rotatably arranged transparent disk deflecting measuring beams emanating from the light source into different solid angle sectors;

a transmitter trigger and drive regulation circuit for the synchronization of transmitter trigger pulse sequences and for the rotation of the transparent disk;

said transmitter trigger and drive regulation circuit outputting transmitter trigger signals at a transmitter trigger frequency which is in a defined relationship to the rotational speed of the rotatable transparent disk;

said transmitter trigger and drive regulation circuit comprising;

a frequency-stable generator;

a frequency divider and frequency counter arranged in circuit after said frequency-stable generator;

said frequency counter serving to produce pulse sequences for a time grid;

drive means for rotating said transparent disk;

a light barrier for monitoring the rotation of the transparent disk;

said transmitter trigger and drive regulation circuit further comprising;

a phase comparator for comparing pulses of the light barrier monitoring the rotation of the transparent disk with pulses of the time grid;

said phase comparator having a regulation output and a control output;

a power amplifier;

said regulation output of said phase comparator being connected by means of said power amplifier with said drive means for said transparent disk;

said frequency counter having outputs;

two flip-flops each provided with inputs and outputs;

the control output of the phase comparator and the outputs of the frequency counter being connected with the inputs of said two flip-flops;

a first AND-gate and second AND-gate;

said second AND-gate having first and second inputs;

the outputs of the two flip-flops being connected by said first AND-gate with said first input of said second AND-gate;

the second input of said second AND-gate having inputted thereto a transmitter trigger pulse sequence from the frequency counter;

said second AND-gate being rendered conductive owing to logical linking of its inputted signals only upon synchronization of the rotation of the transparent disk with the time grid;

said transmitter trigger and drive regulation circuit having an output; and

the output of the transmitter trigger and drive regulation circuit being connected with the light source.

13. A method of measuring the velocity of a moving object by means of pulsed optical radiation, comprising the steps of:

forming at least one measuring beam from a sequence of optical pulses;

directing said at least one measuring beam from a transmission site to the moving object whose velocity is to be measured;

receiving and evaluating said at least one measuring beam reflected by the moving object in order to determine transit times of the optical pulses forming said at least one measuring beam from said site of transmission to the moving object and back from the moving object to said site of transmission;

forming distance values from the determined transit times and distance differences from the distance values;

determining values of said velocity of said moving object by dividing the formed distance differences by related time spans of relevant pulse sequences;

said step of determining said velocity values including the steps of;

selecting sequences of successive distance values and successive distance differences, each of which successive distance values and successive distance differences falls within a related predetermined tolerance range and is measured at a substantially constant velocity of said moving object; and

determining a reliable velocity value by dividing the sum of at least one such sequence of successive distance differences by the sum of related ones of said time spans.

14. The method as defined in claim 13, wherein:

said step of directing said at least one measuring beam from the transmission site to the moving object whose velocity is to be measured entails directing at least two spatially separate measuring beams towards said moving object;

said step of receiving and evaluating said at least one measuring beam reflected by said moving object entails the step of separately receiving and evaluating each one of said at least two spatially separate measuring beams in order to separately determine for each such measuring beam the related transit times;

said step of forming distance values from the determined transit times and forming distance differences from such distance values entails the step of separately forming distance values and distance differences for each one of said at least two spatially separate measuring beams;

said step of determining values of said velocity of said moving object entails the step of separately determining said reliable velocity for each one of said at least two spatially separate measuring beams; and

determining as binding velocity values a predetermined number of reliable velocity values which originate from different ones of said at least two spatially separate measuring beams and which fall within a predetermined range of tolerance.

15. The method as defined in claim 14, wherein:

the step of directing said at least two spatially separate measuring beams towards said moving object encompasses directing in the range of 4 to 6 spatially separate measuring beams to the moving object whose velocity is to be measured.

16. The method as defined in claim 14, further including the step of:

automatically interrupting the velocity measurement when there are not obtained, after a predetermined duration of such measurement, at least two reliable velocity values which originate from different ones of said spatially separate measuring beams and which fall within said predetermined range of tolerance.

17. The method as defined in claim 14, wherein:

said step of determining said binding velocity value entails the steps of averaging the velocity values obtained from the different spatially separate measuring beams and falling within said predetermined range of tolerance; and

considering the average velocity value thus obtained as said binding velocity value.

18. The method as defined in claim 13, wherein:

said step of forming said at least one measuring beam entails the step of forming said at least one measuring beam from a sequence of essentially uniformly spaced optical pulses.

19. An apparatus for measuring the velocity of a moving object by means of pulsed optical radiation, comprising:

a pulsed light source generating pulsed optical radiation;

a transmitter optical system transmitting said pulsed optical radiation towards the moving object whose velocity is to be measured;

said transmitter optical system having an optical axis;

a receiver optical system receiving reflected pulsed optical radiation from said moving object;

a receiver upon which said reflected pulsed optical radiation is directed by means of said receiver optical system;

said receiver receiving said reflected pulsed optical radiation after a transit time which depends upon the distance of said moving object from the velocity measuring apparatus;

circuit means operatively connected with said receiver in order to determine distance values of the moving object from said transit times, distance differences from such distance values, and velocity values of said moving object from the determined distance differences and transit times;

said circuit means temporarily storing a plurality of determined distance differences; and

said circuit means further comprising means for comparing each new determined distance difference with said stored determined distance differences in order to obtain at least one sequence of consecutive such distance differences which fall within a predetermined range of tolerance and which are homogeneous with respect to the velocity of the moving object.

20. The apparatus as defined in claim 19, further including:

a transparent disk arranged for rotation with respect to said optical axis of said transmitter optical system and between said pulsed light source and said transmitter optical system;

said transparent disk being inclined with respect to said optical axis;

said transparent disk deflecting said pulsed optical radiation generated by said pulsed light source into a predetermined number of different solid angle sectors; and

said circuit means storing said determined velocity values determined for each one of said predetermined number of different solid angle sectors and comparing said stored determined velocity values associated with different ones of said solid angle sectors.

21. The apparatus as defined in claim 20, further including:

a transmitter trigger and drive regulation circuit synchronizing said rotation of said transparent disk with a transmitter trigger pulse sequence which is in a defined relationship with the speed of said rotation of said transparent disk, and comprising;

a frequency-stable generator;

a frequency divider and frequency counter arranged in circuit after said frequency-stable generator;

said frequency counter serving to produce pulse sequences for a time grid;

drive means for rotating said transparent disk;

a light barrier for monitoring the rotation of the transparent disk;

a phase comparator for comparing pulses generated by means of the light barrier which monitors the rotation of the transparent disk, with pulses of the time grid;

said phase comparator having a regulation output and a control output;

a power amplifier;

said regulation output of said phase comparator being connected by means of said power amplifier with said drive means for said transparent disk;

said frequency counter having outputs;

two flip-flops each provided with inputs and outputs;

the control output of the phase comparator and the outputs of the frequency counter being connected with the inputs of said two flip-flops;

a first AND-gate and second AND-gate;

said second AND-gate having first and second inputs;

the outputs of the two flip-flops being connected by means of said first AND-gate with said first input of said second AND-gate;

the second input of said second AND-gate having inputted thereto a transmitter trigger pulse sequence from the frequency counter;

said second AND-gate being rendered conductive owing to logical linking of its inputted signals only upon synchronization of the rotation of the transparent disk with the time grid;

said transmitter trigger and drive regulation circuit having an output; and

the output of the transmitter trigger and drive regulation circuit being connected with the light source.

22. The apparatus as defined in claim 19, wherein:

said pulsed light source generates a sequence of essentially uniformly spaced pulses of said optical radiation.