Apparatus and method for measuring distance from and speed components of an object traveling vertical to a reference line

• US 4,111,552 A
• Filed: 10/13/1976
• Issued: 09/05/1978
• Est. Priority Date: 10/17/1975
• Status: Expired due to Term

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Bodlaj, Viktor
• Primary Examiner(s): Buczinski, S. C.
• Application Number:
  US05/731,650
• Time in Patent Office: 692 Days
• Field of Search: 356/1, 356/28, 356/4, 356/5, 356/141, 356/152, 307/234, 328/109, 328/110, 328/111, 328/112, 328/130, 343/13 R
• US Class Current: 356/3.02
• CPC Class Codes: G01S 17/14 wherein a voltage or current pulse is initiated and terminated in accordance with the pulse transmission and echo reception respectively, e.g. using counters
• CPC Class Codes: G01S 17/50 Systems of measurement based on relative movement of target

Abstract

A method and apparatus for the rapid measurement of the distance of an object from a reference point and the speed component of an object traveling vertical to a reference plane is disclosed. A laser beam from a transmitter is periodically sent by a beam deflector through the space in which the object is situated. The laser beam is diffusely reflected from the object and is registered as a measurement pulse on a detector placed near the transmitter. The distance of the object is determined from the time difference between one starting point of a deflected beam segment selected for the measurement and the detector signal. A reference pulse is created in an additional reference detector at a reference time by positioning a swing mirror so that a portion of the laser beam is reflected on a transparent body situated on the reference plane, the reflection then impinging upon the reference detector. The time difference is measured from the reference time to the middle of the measurement pulse.

Claims

1. A method for the rapid measurement of the distance of an object from a reference point comprising the steps of:

a. periodically sending a laser beam from a transmitter through a space in which the object is situated by use of a beam deflector;

b. providing a detector means near the transmitter for picking up light from a given direction only;

c. diffusely reflecting the laser beam from the object and registering reflected light on the detector means to create a measurement pulse having start and finish times associated with a respective rise and fall of the measurement pulse;

d. providing a reference reflector means in the path of the transmitted laser beam so as to create a reference pulse when said laser beam is transmitted;

e. receiving the reference pulse with a reference detector to create a reference pulse at a reference time;

f. determining an exact middle of the measurement pulse by circuitry means utilizing the start and finish times of the measurement pulse and including measuring separately the time differences from the reference time to the respective start and finish times; and

g. calculating the distance from an average of the time differences.

2. A method according to claim 1, further including the steps of shaping the measurement pulse in a pulse former, feeding the shaped pulse in parallel to two differentiators for respectively creating first and second pulses representative of rising and falling edges of the shaped pulse and comparing in respective pulse discriminators the reference pulse with the first and second pulses respectively to create first and second timing pulses.

3. A method according to claim 2, including the further steps of converting the first and second timing pulses originating in the pulse discriminators to voltages which are summed, halved and displayed in analog form.

4. A method according to claim 2, including the further steps of digitalizing the first and second timing pulses originating in the pulse discriminators.

5. A method according to claim 4, including the further steps of summing, halving and digitally displaying the digitalized first and second timing pulses.

6. A method according to claim 4, including the further steps of converting the digitalized first and second timing pulses into analog pulses and summing, halving and displaying the analog pulses in analog form.

7. A method for the rapid measurement of the distance of an object from a reference point comprising the steps of:

a. periodically sending a laser beam from a transmitter through a space in which the object is situated by use of a beam deflector;

b. providing a detector means near the transmitter for picking up light from a given direction only;

c. diffusely reflecting the laser beam from the object and registering reflected light on the detector means to create a measurement pulse having start and finish times associated with a respective rise and fall of the measurement pulse;

d. providing a reference reflector means in the path of the transmitted laser beam so as to create a reference pulse when said laser beam is transmitted;

e. receiving the reference pulse with a reference detector to create a reference pulse at a reference time;

f. determining an exact middle of the measurement pulse by circuitry means utilizing the start and finish times of the measurement pulse and measuring the time difference from the reference time to the time corresponding to the exact middle of the measurement pulse;

g. calculating the distance from the time difference;

h. shaping the reference pulse in a pulse former, connecting the shaped reference pulse to a pulse discriminator for producing a control signal from the reference time to the point in time of a falling edge of the measurement pulse, and controlling said measuring step with said control signal of the pulse discriminator; and

i. digitalizing a voltage with a frequency f by use of an oscillator from the reference time until the time represented by a rising edge of the measurement pulse to create counting pulses, digitalizing the measurement pulse with a frequency f/2 to create counting pulses, and counting the digitalized voltage and digitalized measurement counting pulses during the period of the control signal.

8. A method for the rapid measurement of the distance of an object in a space from a reference point, comprising the steps of:

a. periodically sending a laser beam from a transmitter by a beam deflector through the space in which the object is situated, said beam diffusely reflecting from the object;

b. registering a measurement pulse of the diffusely reflected beam on a detector placed near the transmitter and which detector can only pick up light from a given direction, said measurement pulse having start and finish times associated with a respective rise and fall of the measurement pulse;

c. creating a reference pulse in a reference detector at a reference time using a swing mirror positioned such that the periodically sent laser beam is reflected on a transparent member situated on the reference line to hit the reference detector; and

d. determining a middle of the measurement pulse by circuitry means utilizing the start and finish times of the measurement pulse and which measures separately the time differences between the reference time and the respective start and finish times and averages the time differences so as to determine the distance of the object from a time difference between a starting point of the reference pulse and the middle of the measurement pulse.

9. An apparatus for the rapid measurement of the distance of an object from a reference point, comprising:

a. a laser beam transmitter;

b. beam deflector means for periodically sending a laser beam through space in which said object is situated;

c. detector means placed near the transmitter for registering a measurement pulse of a beam diffusely reflected from the object, said measurement pulse having start and finish times associated with a respective rise and fall of the measurement pulse;

d. a transparent member means for passing a portion of said laser beam and reflecting a portion of said laser beam;

e. a reference detector means for creating a reference pulse in a reference detector at a reference time when said portion reflected by the transparent member is received;

f. means for determining the distance of the object from a time difference between a start of the reference pulse and a middle of the measurement pulse, said means for determining the distance further including circuitry means for determining said middle of the measurement pulse by utilizing the start and finish times of the measurement pulse to measure separately the time differences between the reference time and the respective start and finish times and averaging the time differences.

10. The apparatus according to claim 9 in which first and second differentiator means are provided to determine the points in time of the rising and falling edge of the measurement pulse, and pulse discriminator means are provided for comparison of the reference time with each of said points in time and for creating output timing pulses in response thereto.

11. The apparatus according to claim 10 in which means for summing, halving and displaying said output timing pulses in analog form are provided.

12. Apparatus according to claim 10 in which means for digitalizing the pulses originating in the pulse discriminator means are provided.