Method and apparatus for measuring position of object for vehicle

• US 6,433,856 B1
• Filed: 09/14/2000
• Issued: 08/13/2002
• Est. Priority Date: 11/10/1999
• Status: Expired due to Fees

• Current Assignee: Tae-Oog Yoo
• Original Assignee: Tae-Oog Yoo
• Inventors: Yoo, Tae-Oog
• Primary Examiner(s): Buczinski, Stephen C.
• Application Number:
  US09/662,147
• Time in Patent Office: 698 Days
• Field of Search: 180/169, 356/3.01, 356/3.09, 356/3.1, 356/3.11
• US Class Current: 356/3.01
• CPC Class Codes: B60T 7/22 initiated by contact of vehicle, e.g. bumper, with an external object, e.g. another vehicle , or by means of contactless obstacle detectors mounted on the vehicle
• CPC Class Codes: G01S 17/003 Bistatic lidar systems; Multistatic lidar systems
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/87 Combinations of systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 7/486 Receivers
• CPC Class Codes: G01S 7/487 Extracting wanted echo signals , e.g. pulse detection

Abstract

In a method, the light beams of two separated optical radar units (each of which are capable of emitting light pulses in a direction and receiving light pulses from the same direction) are directed to a point. The first optical radar unit emits a light pulse to the point and the second optical radar unit detects the light pulse reflected from the object at the point. After a time interval, the second optical radar unit emits a light pulse to the point and the first optical radar unit detects the light pulse reflected from the object at the point. If there is an object at the point, the time difference of the two detected signals from the two optical radar units is the switching time interval. By comparing the two detected signals from the two optical radar units, one can determine whether an object is at the point.

Claims

1. A method for measuring a position of an object employing at least two separate optical radar units separated by a distance, wherein each optical radar unit can emit light pulses in a direction and receive light pulses coming from the same direction as the emitted light beam, comprising:

setting the two separate optical radar units such that the two separate optical radar units are directed to a point;

emitting a light pulse to the point at time t by one of the two optical radar units, which is called the first optical radar unit and detecting the light pulse reflected from the point by the other optical radar unit, which is called the second optical radar unit;

switching the functions of the two optical radar units after a switching time interval dt such that the second optical radar unit emits a light pulse to the point at time t+dt and the first optical radar unit detects the light pulse reflected from the point;

comparing the two signals detected by the first and the second optical radar units to determine whether the time difference of the two detected signals is the switching time interval dt;

determining the position of the point on the basis of the two directions and the separation of the two optical radar units;

displaying the result of the comparison of the two detected signals at the position of the point to determine whether an object is at the point and to measure the position of the object if the object is at the point; and

scanning a predetermined area by changing the two directions of the two optical radar units.

2. The method of claim 1, further comprising:

storing at least one predetermined sequence of the two directions of the two optical radar units; and

scanning a predetermined area.

3. An apparatus for measuring a position of an object comprising:

at least two optical radar units separated by a distance, each of which can emit light pulses in a direction and receive light pulses coming from the same direction;

a direction changing means for changing the directions of the two optical radar units such that the two optical radar units are directed to a point;

a signal processor that processes signals detected by the optical radar units;

a switch controller and switch that switch the functions of the two optical radar units after a switching time interval dt;

a signal comparing means for comparing the detected signals;

a position determining means for calculating the position of the point using the directions of the two optical units and the distance;

a display means for displaying the output of the signal comparing means at the position of the point to determine whether an object is at the point and to measure the position of the object if the object is at the point;

a memory that stores at least one predetermined sequence of two directions of the two optical radar units; and

a microprocessor that executes the sequence stored in the memory.

4. The apparatus of claim 3, wherein the signal comparing means comprises a time delay circuit and a multiplier circuit.

5. A method for measuring a position of an object employing an optical radar unit and a light detecting means separated by a distance, wherein the optical radar unit can emit light pulses in a first direction and receive light pulses coming from the same direction as the emitted light beam, and wherein the light detecting means can detect light pulses coming from a second direction, comprising:

setting directions of the optical radar unit and the light detecting means such that the optical radar unit and the light detecting means are directed to a point;

emitting a light pulse to the point by the optical radar unit;

detecting the light pulse reflected from the point by the optical radar unit and the light detecting means at the same time;

comparing the two signals detected by the optical radar unit and the light detecting means to determine whether the optical radar unit and the light detecting means detected the reflected light pulse at the same time;

determining the position of the point on the basis of the two directions and the distance;

displaying the position of the point from the signal comparing means to determine whether an object is at the point and to measure the position of the object if the object is at the point; and

scanning a predetermined area by changing the directions of the optical radar unit and the light detecting means.

6. The method of claim 5, further comprising:

storing at least one predetermined sequence of the two directions of the optical radar unit and the light detecting means;

scanning the predetermined area;

executing the at least one predetermined sequence.