Method and device for association of anonymous reflectors to detected angle positions

• US 6,259,979 B1
• Filed: 04/13/2000
• Issued: 07/10/2001
• Est. Priority Date: 10/17/1997
• Status: Expired due to Term

• Current Assignee: Kollmorgen Automation AB (Altra Industrial Motion Corp.)
• Original Assignee: Apogeum AB
• Inventors: Holmquist, Fredrik
• Primary Examiner(s): NGUYEN, TAN QUANG
• Time in patent office: 453 Days
• Field of Search: 701/23, 701/24, 701/25, 701/26, 701/28, 342/126, 342/154, 340/903, 340/435
• US Class Current: 701/23
• CPC Class Codes: B66F 9/063 Automatically guided
• CPC Class Codes: G01S 17/74 Systems using reradiation of electromagnetic waves other than radio waves, e.g. IFF, i.e. identification of friend or foe
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 5/16 using electromagnetic waves other than radio waves
• CPC Class Codes: G05D 1/0236 in combination with a laser lasers per se H01S
• CPC Class Codes: G05D 1/0272 comprising means for registering the travel distance, e.g. revolutions of wheels measuring distance traversed on the ground by vehicles, e.g. using odometers G01C22/00
• CPC Class Codes: G05D 2201/0216 Vehicle for transporting goods in a warehouse, factory or similar

Abstract

A method for association of anonymous reflectors (R₁-R₁₁) to detected angle positions, whereby a) the anonymous reflectors are arranged in positions in a transport area; b) positions of the reflectors (R1-R11) are stored in first memory means (20); c) a beam (B) is emitted from an emission source (13) of a vehicle (10) over a search sector; d) reflected signals from reflecting objects are received on board the vehicle (10); e) an angle position towards reflecting objects in relation to a reference direction (D) of the vehicle (10) is continuously detected by detector means (18) during the sweep of the beam over the search sector, and corresponding angle values are determined; f) at least one angle value determined over the search sector is stored in a second memory means (21). The distances between reflectors (R₁-R₁₁) are a reference point on the vehicle (10) is determined continuously by a control means (19). A relation between the distance values and the corresponding distances between stored reflector positions and a position assumed for the vehicle is determined by control means (19), the association being allowed if the relation is within an expected interval.

Claims

1. A method for association of anonymous reflectors (R₁-R₁₁) to detected angle positions, whereby

a) the anonymous reflectors are arranged in positions in a transport area,

b) positions of the reflectors (R₁-R₁₁) are stored in memory,

c) a beam (B) is emitted from a vehicle (10) over a search sector,

d) reflected signals from reflecting objects are received on board the vehicle (10),

e) an angle position towards reflecting objects in relation to a reference direction (D) of the vehicle (10) is detected over the search sector and corresponding angle values are determined,

f) at least one angle value determined over the search sector is stored,

characterized by

continuously measuring a distance between a reflector (R₁-R₁₁) and a reference point on the vehicle (10) to obtain a distance value,

determining a relation between the distance value and corresponding distance between a stored reflector positions and a position assumed for the vehicle, and

allowing the association if the relation is within an expected interval.

2. A method according to claim 1, characterized in

that the duration of the reflected signals are continuously detected during the sweep of the beam over the search sector, and the value of the duration is determined,

that a relation between the value of the duration and an expected value is determined, and

that the association is allowed, if the relation is within an expected interval.

3. A method according to claim 2, characterized in

that the reflectors (R₁-R₁₁) are made plane,

that the expected intensity of a signal reflected from a reflector (R₁-R₁₁) at different distances is established in the form of intensity reference values,

that the expected duration of a signal reflected from a reflector (R₁-R₁₁) at different distances is established in the form of duration reference values,

that the expected intensity of a signal reflected from a reflector (R₁-R₁₁) with respect to the angle position of reflector (R₁-R₁₁) in relation to a normal direction is established in the form of an angle factor,

that an angle position of the reflectors (R₁-R₁₁) in relation to the angle of line-of-sight to the vehicle (10) is determined on the basis of the relation between the detected duration and the duration reference values,

that the expected intensity value from a reflector (R₁-R₁₁) at the distance measured from the reference point is adjusted with regard to the intensity reference value and the angle factor, and

that the association is allowed, if the intensity of the reflected signal is within a predetermined interval around the adjusted intensity value.

4. A method according to claim 3, characterized in

that the intensity reference values at different distances are stored as values in a table,

that duration reference values at different distances are stored in a table, and

that angle factors at different angles are stored in a table, the table values being used when assessing whether to allow association.

5. A method according to claim 1, characterized in

that the expected duration of a reflected signal at different distances between the reflector and the reference point on board the vehicle is established in the form of duration reference values,

that the duration of the reflected signals are continuously detected during the sweep of a beam moving over the search sector, and the value of the duration is determined,

that a relation between the duration reference value and measured duration value is determined, and

that the association is allowed, if the relation is within an expected interval.

6. A method according to claim 1, characterized in

that the expected intensity of a reflected signal at different distances between the reflector and the reference point on board the vehicle is established in the form of intensity reference values,

that an intensity value of reflections from reflective objects is determined,

that the relation is established between the determined intensity value and an expected intensity value of a reflected signal at the measured distance, and

that the association is allowed, if the relation is within an expected interval.

7. A method according to claim 1, characterized in

that the emitted beam (B) is modulated,

that the reflection received from objects in the transport area is compared with the emitted beam with regard to time delay, and

that the distance between the vehicle (10) and the object is determined on the basis of the time delay between a certain phase position of the emitted beam and the corresponding phase position of the received beam.

8. A method according to claim 7, characterized in that the emitted signal is modulated with a square wave with a frequency of approximately 2 MHz.

9. A method according to claim 1, characterized in that the emitted beam (B) is a laser beam.

10. A method according to claim 1, characterized in that the emitted beam (B) is constituted of microwave radiation.

11. A device for association of multiple anonymous reflectors (R₁-R₁₁) present in a transport area, to detected angle positions, comprising:

a) a vehicle (10) with a drive and steering unit (14),

b) a first memory (20) for storing the positions of the reflectors (R₁-R₁₁),

c) an emission source (13) for emitting a beam (B), and a controller (19) for moving the beam (B) from the vehicle (10) over a search sector,

d) a detector (18) for continuous angle position detection of a reflected signal in relation to a reference direction (D) of the vehicle (10) during the sweep of the beam over the search sector, and for determination of the corresponding angle value,

e) a second memory (21) for storing multiple angle values determined over the search sector,

characterized in

that the controller (19) is provided to continuously measure the distances between the reflectors (R₁-R₁₁) and a reference point on board vehicle (10) using the reflected signal and to store the corresponding distance values in memory (20), and

that the controller (19) is provided to continuously determine a relation between the distance values and the corresponding distances between stored reflector positions and a position assumed for the vehicle, the association being allowed if the relation is within an expected interval.

12. A device according to claim 11, characterized in that the controller (19) is provided to continuously detect the duration of reflected signals during the sweep of the beam over the search sector and determine a value of the duration.

13. A device according to claim 11, characterized in that the controller (19) is provided to continuously detect the intensity of reflected signals during the sweep of the beam over the search sector and determine a value of the intensity.

14. A device according to claim 13, characterized in that the first memory (20) is provided to store, as intensity reference values, an expected intensity value of a signal reflected from a reflector (R₁-R₁₁) depending on the distance between reflector (R₁-R₁₁) and the detector (18).

15. A device according to claim 11, characterized in that the first memory (20) is provided to store, as duration reference values, the expected duration of a signal reflected at different distances between the reflector and the reference point on board the vehicle.

16. A device according to claim 15, characterized in

that the reflectors (R₁-R₁₁) are made plane,

that the controller (19) is provided to continuously determine an angle factor from a relation between the determined value of the duration and a duration reference value, and

that the controller (19) is provided to continuously adjust the expected intensity value with regard to the angle factor and the intensity reference value, the association being allowed if the relation between the adjusted intensity value and the determined intensity value is within an expected interval.

17. A device according to claim 11, characterized in

that drive and steering unit (14) is provided to modulate beam (B), and

that drive and steering unit (14) is provided to determine the distance between the vehicle and reflector (R₁-R₁₁) depending on the time offset between the phase position of the emitted beam (B) and the corresponding phase position of the received beam.