Apparatus and method for measuring the relative velocity and true distance between two objects

• US 6,104,671 A
• Filed: 03/28/1996
• Issued: 08/15/2000
• Est. Priority Date: 03/28/1996
• Status: Expired due to Fees

• Current Assignee: John F. Lanza, Reed W. Hoyt
• Original Assignee: John F. Lanza, Reed W. Hoyt
• Inventors: Lanza, John F., Hoyt, Reed W.
• Primary Examiner(s): Lobo, Ian J.
• Application Number:
  US08/623,600
• Time in Patent Office: 1,601 Days
• Field of Search: 367/99, 367/908, 367/118, 367/120, 367/124, 367/127, 367/89, 367/105, 342/106, 342/109, 342/125
• US Class Current: 367/99
• CPC Class Codes: G01S 15/10 using transmission of interrupted, pulse-modulated waves determination of distance by phase measurement G01S15/32
• CPC Class Codes: G01S 15/58 Velocity or trajectory determination systems; Sense-of-movement determination systems velocity measurement in imaging systems G01S15/8979

Abstract

An apparatus and method for measuring the true distance and relative velocity between first and second objects. The apparatus comprises a transceiver located at the first object which measures a first transit time for the transmission of a first signal from a first object to a second object and for the reflection of the first signal from the second object back to the first object. The transceiver further measures a second transit time for the transmission and reflection of a second signal, the second signal being transmitted immediately upon the reflection of the first signal back to the first object. First and second transit times can be used to calculate first and second apparent distances between the first and second objects, respectively. The apparatus also includes calculating means for determining the relative velocity between the first and second objects using the first transit time and the second transit time. The calculating means calculates the true distance between the first and second objects at the time of reflection of the second signal by modifying the second apparent distance in accordance with the relative velocity between the first and second objects during the time of transmission and reflection of the second signal.

Claims

1. A method for measuring the true distance and relative velocity between first and second objects, said method comprising the steps of:

a. measuring a first transit time for the transmission and reflection of a first signal from the first object to the second object and then back to the first object using a transceiver located at the first object, said first transit time being used to determine a first apparent distance between the first and second objects;

b. measuring a second transit time for the transmission and reflection of a second signal from the first object to the second object and then back to the first object using the transceiver located at the first object, said second transit time being used to determine a second apparent distance between the first and second objects, wherein the second signal is transmitted immediately upon the reflection of the first signal back to the first object;

c. calculating the relative velocity between the first and second objects using said first and second transit times; and

d. calculating the true distance between the first and second objects at the time of reflection of the second signal back to the first object by modifying the second apparent distance in accordance with the relative velocity between the first and second objects during the time of transmission and reflection of the second signal.

2. The method of claim 1 wherein the relative velocity between the first and second objects is calculated using a ratio of said first transit time and said second transit time.

3. The method of claim 1 wherein the first and second signals are acoustic signals.

4. The method of claim 1 wherein the first and second signals are ultrasonic signals.

5. An apparatus for measuring the true distance and relative velocity between first and second objects, comprising:

a. a transceiver located at the first object, said transceiver measuring a first transit time for the transmission and reflection of a first signal from the first object to the second object and then back to the first object, said first transit time being used to determine a first apparent distance between the first and second objects;

b. wherein said transceiver measures a second transit time for the transmission and reflection of a second signal from the first object to the second object and then back to the first object, said second transit time being used to determine a second apparent distance between the first and second objects, wherein the second signal is transmitted immediately upon the reflection of the first signal back to the first object; and

c. calculating means for determining the relative velocity between the first and second objects using said first transit time and said second transit time;

d. wherein said calculating means calculates the true distance between the first and second objects at the time of reflection of the second signal back to the first object by modifying the second apparent distance in accordance with the relative velocity between the first and second objects during the time of transmission and reflection of the second signal.

6. The apparatus of claim 5 wherein the first and second signals are acoustic signals.

7. The apparatus of claim 5 wherein the first and second signals are ultrasonic signals.

8. The apparatus of claim 5 wherein said calculating means comprises a microprocessor.

9. The apparatus of claim 8 wherein the microprocessor of said calculating means comprises a digital-to-analog convertor, a counter, a random access memory, and an arithmetic logic unit.

10. The apparatus of claim 5 wherein said transceiver is a piezo transducer.