Anti-interference speed detection methods and detectors thereof

• US 20060132756A1
• Filed: 03/22/2005
• Published: 06/22/2006
• Est. Priority Date: 12/16/2004
• Status: Active Grant

• Current Assignee: Asia Optical Company Incorporated
• Original Assignee: Asia Optical Company Incorporated
• Inventors: Huang, Dong
• Granted Patent: US 7,199,867 B2
• Time in Patent Office: Days
• US Class Current: 356/28
• CPC Class Codes: G01S 17/50 Systems of measurement based on relative movement of target

Abstract

A speed detection method is implemented in a speed detector comprising a range finder. First, a specific number of distance measurement samples of an object are acquired during a period of time utilizing the range finder. The distance measurement samples are converted to M versions of the distance measurement samples respectively based on M velocities, wherein M is a positive integer. Each version of the distance measurement samples comprises reflected distance measurement laser pulses. Each reflected pulse corresponds to a measured distance and a received pulse order. A version of the distance measurement samples is determined, which comprises a distance range to which the highest number of reflected pulses corresponds. A speed of the object is calculated based on an assumed velocity to which the determined version corresponds.

Claims

1. A speed detection method, implemented in a speed detector comprising a range finder, comprising:

acquiring a specific number of distance measurement samples of an object during a period of time utilizing the range finder;

converting the distance measurement samples based on velocities of M assumed observers to generate M versions of the distance measurement samples respectively corresponding to the velocities of M assume observers, wherein M is a positive integer, each version of the distance measurement samples comprises reflected distance measurement laser pulses, and each reflected pulse corresponds to a measured distance and a received pulse order;

determining a version of the distance measurement samples comprising a distance range to which the highest number of reflected pulses corresponds; and

calculating a speed of the object based on an assumed velocity to which the determined version corresponds.

2. The method as claimed in claim 1, wherein calculation of a speed of the object comprises adopting the assumed velocity as the speed of the object.

3. The method as claimed in claim 1, wherein the distance range comprises an interval between two adjacent scales measured with an original unit of measurement of the speed detector.

4. The method as claimed in claim 1, wherein after the distance measurement samples are converted to a second version of the distance measurement samples based on an velocity Vn of an assumed observer, a first reflected signal in the distance measurement samples corresponding to received pulse order Tx and measured distance Dx is converted to a second reflected pulse in the second version corresponding to received pulse order Tx and measured distance (Dx−

Vn×

Δ

T×

Tx), wherein Δ

T is an interval between two adjacent received pulse orders.

5. The method as claimed in claim 1, further comprising:

acquiring a new unit of measurement exceeding movement distances of the object in a first period;

calculating a rough measured distance D1 corresponding to the locations of the object in the first period by comparing portions of the distance measurement samples corresponding to the first period utilizing the new unit of measurement; and

determining the distance range based on the rough measured distance D1.

6. The method as claimed in claim 5, wherein the rough measured distance D1 is represented by a scale measured with the new unit of measurement, to which the highest number of reflected pulses in the distance measurement samples within the first period corresponds.

7. The method as claimed in claim 1, further comprising determining the M assumed velocities of the assumed observers based on a maximum velocity, a minimum velocity, and a unit of speed measurement.

8. A speed detector, comprising:

a range finder acquiring a specific number of distance measurement samples of an object during a period of time;

a processor coupled to the range finder, converting the distance measurement samples based on velocities of M assumed observers to generate M versions of the distance measurement samples respectively corresponding to the velocities of M assumed observers, wherein M is a positive integer, each version of the distance measurement samples comprises reflected distance measurement laser pulses, each reflected pulse corresponds to a measured distance and a received pulse order, an the processor determines a version of the distance measurement samples comprising a distance range to which the highest number of reflected pulses corresponds and calculates a speed of the object based on an velocity of assumed observer to which the determined version corresponds.

9. The speed detector as claimed in claim 8, wherein the processor adopts the velocity of assumed observer as the speed of the object.

10. The speed detector as claimed in claim 8, wherein the distance range comprises an interval between two adjacent scales measured with an original unit of measurement of the speed detector.

11. The speed detector as claimed in claim 8, wherein after the distance measurement samples are converted to a second version of the distance measurement samples based on an velocity Vn of an assumed observer, a first reflected signal in the distance measurement samples corresponding to received pulse order Tx and measured distance Dx is converted to a second reflected pulse in the second version corresponding to received pulse order Tx and measured distance (Dx−

Vn×

Δ

T×

Tx), wherein Δ

T is an interval between two adjacent received pulse orders.

12. The speed detector as claimed in claim 8, wherein the processor acquires a new unit of measurement larger than movement distances of the object in a first period, calculates a rough measured distance D1 corresponding to the locations of the object in the first period by comparing portions of the distance measurement samples corresponding to the first period utilizing the new unit of measurement, and determines the distance range based on the rough measured distance D1.

13. The speed detector as claimed in claim 12, wherein the rough measured distance D1 is represented by a scale measured with the new unit of measurement, to which the highest number of reflected pulses in the distance measurement samples within the first period corresponds.

14. The speed detector as claimed in claim 8, wherein the processor determines the M assumed velocities of the assumed observers based on a maximum velocity, a minimum velocity, and a unit of speed measurement.