LASER DIODE BASED MULTIPLE-BEAM LASER SPOT IMAGING SYSTEM FOR CHARACTERIZATION OF VEHICLE DYNAMICS

• US 20120044477A1
• Filed: 04/19/2010
• Published: 02/23/2012
• Est. Priority Date: 04/29/2009
• Status: Active Grant

• Current Assignee: TRUMPF Photonic Components GmbH (TRUMPF SE + Co. KG)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Han, Meng
• Granted Patent: US 9,869,689 B2
• Time in Patent Office: Days
• US Class Current: 356/28
• CPC Class Codes: B60T 2250/04 Vehicle reference speed; Vehicle body speed
• CPC Class Codes: B60T 8/172 Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters B60T8/17551 takes precedence
• CPC Class Codes: B60W 40/11 Pitch movement
• CPC Class Codes: B60W 40/112 Roll movement
• CPC Class Codes: B60W 40/114 Yaw movement
• CPC Class Codes: G01P 21/02 of speedometers
• CPC Class Codes: G01P 3/366 by using diffraction of light for measuring speed of fluids G01P5/26
• CPC Class Codes: G01S 17/06 Systems determining position data of a target
• CPC Class Codes: G01S 17/58 Velocity or trajectory determination systems; Sense-of-movement determination systems
• CPC Class Codes: G01S 7/48 of systems according to group G01S17/00

Abstract

The invention is related to a laser diode based multiple beam laser spot imaging system for characterization of vehicle dynamics. A laser diode based, preferably VCSEL based laser imaging system is utilized to characterize the vehicle dynamics. One or more laser beams are directed to the road surface. A compact imaging system including an imaging matrix sensor such as a CCD or CMOS camera measures locations or separations of individual laser spots. Loading status of vehicles and vehicles'"'"' pitch and roll angle can be characterized by analyzing the change of laser spot locations or separations.

Claims

1. An optical vehicle laser sensor system for detection of vehicle dynamics parameters, comprising

a laser device for generating at least one laser beam, so that said laser beam generates a laser spot on a reference surface placed opposite to the laser device,

an imaging device comprising at least one matrix sensor with a lens for imaging said laser spot onto said reference surface, said imaging device being arranged so that said laser spot onto said reference surface is visible within a field of view (40) of said imaging device, whereby the optical axis of said imaging device and the direction of said laser beam are non-coincident,

a detector for detecting a velocity of said optical vehicle laser sensor system relatively to said reference surface from the signal of said laser beam reflected or scattered back from said reference surface,

a data processing device for detecting the laser spot location within the image data retrieved from said imaging device, and calculating the orientation of said optical vehicle laser sensor system from the spot location.

2. The optical vehicle laser sensor system according to claim 1, wherein said laser device is configured to generate three spatially separated laser beams, so that the three laser beams generate three laser spots on the reference surface placed opposite to the laser device, wherein two pairs of the spots are separated along two different lateral directions along the reference surface.

3. The optical vehicle laser sensor system according to claim 2, wherein said data processing device is configured to determine lateral distances between the laser spots, and the orientation of said optical vehicle laser sensor system with respect to said reference surface based on said lateral distances.

4. The optical vehicle laser sensor system according to claim 3, wherein the data processing device calculates the distance of the laser device to the reference surface from the location of a laser spot or the mutual distance of the laser spots.

5. The optical vehicle laser sensor system according to claim 2, wherein at least two of the three laser beams are emitted under different angles.

6. The optical vehicle laser sensor system according to claim 1, wherein the detector for detecting a velocity of the optical vehicle laser sensor system relatively to the reference surface comprises a detector for detecting a self-mixing laser intensity oscillation and circuitry for determining the frequency or period of the oscillation.

7. The optical vehicle laser sensor system according to claim 2, wherein said laser device comprises three laser diodes, each generating one of said three laser beams.

8. The optical vehicle laser sensor system according to claim 1, wherein said laser device comprises three vertical cavity surface emitting laser diodes.

9. The optical vehicle laser sensor system according to claim 1, comprising a further laser device laterally offset to the laser device, wherein the laser devices are spaced apart both along a forward direction and transversally to said forward direction.

10. The optical vehicle laser sensor system according to claim 9, wherein said data processing device is configured to determine the distance of the laser device and the further laser device to said reference surface and calculates a roll angle and a pitch angle from said distances.

11. The optical vehicle laser sensor system according to claim 1, wherein said data processing device is set up to calculate at least one of a pitch angle and a roll angle of the vehicle and to correct a velocity measured by said detector based on said pitch angle and roll angle.

12. The optical vehicle laser sensor system according to claim 11, wherein said velocity is corrected by said data processing device by calculating V₀=M_R⁻

1V, wherein V₀=(V_x0, V_y0, V_z0) denotes the corrected velocity vector and V=(V_x, V_y, V_z) denotes the measured velocity vector, and wherein M_R<sup>−

1</sup> is the inverse of matrix;

14. The optical vehicle laser sensor system according to claim 1, further comprising a pulsed power supply for the laser device, wherein said imaging device is synchronized with said pulsed power supply so that images are acquired during a pulse and between two pulses, and wherein said data processing unit subtracts said images acquired during a pulse and between two pulses.

13. (canceled)

15. (canceled)