Headlamp alignment detection using a network of independent sensor units

• US 7,876,427 B1
• Filed: 01/17/2009
• Issued: 01/25/2011
• Est. Priority Date: 01/17/2009
• Status: Active Grant

• Current Assignee: Stephen Waller Melvin
• Original Assignee: Stephen Waller Melvin
• Inventors: Melvin, Stephen Waller
• Primary Examiner(s): Toatley; Gregory J
• Assistant Examiner(s): Underwood; Jarreas C
• Application Number:
  US12/355,779
• Time in Patent Office: 738 Days
• Field of Search: 356121-137
• US Class Current: 356/121
• CPC Class Codes: G01M 11/064 by using camera or other imaging system for the light analysis

Abstract

Headlamp alignment is detected using a collection of intelligent, independent sensor units, each of which incorporates a vertical array of sensing elements capable of detecting headlamp illumination. The sensor units are networked together and can be coupled to a host controller. The host controller can provide a user interface via a touch screen and a Web server, and can further communicate with a plant network for interfacing with manufacturing databases. The network of sensor units can accommodate four or more sensors, which allows multiple vehicles and multiple headlamp types to be audited without physical movement of the sensor units. The sensor units are low in power consumption and can receive power over the same cable providing network communication. Incorporation of non-volatile memory within the sensor units allows factory data to be recorded within each sensor unit and permits convenient replacement of units in the field.

Claims

1. A system for detecting the aim of vehicle headlamps comprising:

a plurality of sensor units, each sensor unit comprising;

a microcontroller;

a plurality of photosensors arranged in a substantially linear array;

a memory storing program code, wherein execution of said program code by said microcontroller provides for the processing of data representing illumination of said plurality of photosensors;

a network interface, wherein each of said plurality of sensor units are coupled to a network through said network interface; and

wherein, each of said sensor units operate substantially independently from each other in said processing of said data.

2. The system of claim 1 wherein each sensor unit further comprises:

a plurality of operational amplifiers coupled to said plurality of photosensors;

an analog multiplexer;

an analog to digital converter;

wherein execution of said program code by said microcontroller further provides for the operation of said analog to digital converter to sample illumination levels at each of said plurality of said photosensors.

3. The system of claim 2 wherein execution of said program code by said microcontroller further provides for a time-domain smoothing of said illumination levels.

4. The system of claim 3 wherein said time-domain smoothing comprises an exponential decay algorithm.

5. The system of claim 2 wherein execution of said program code by said microcontroller further provides for spatial filtering of illumination data.

6. The system of claim 5 wherein said spatial filtering comprises a sliding window with multipliers for adjacent illumination values.

7. The system of claim 2 wherein execution of said program code by said microcontroller further provides for applying equalization correction to illumination data.

8. The system of claim 7 wherein each sensor unit further comprises:

an electrically erasable programmable read only memory (EEPROM) storing equalization information.

9. The system of claim 2 wherein each said sensor unit receives power over a network cable coupled to said network.

10. The system of claim 1 comprising four sensor units positioned at predetermined locations relative to a vehicle being audited and wherein said network comprises a broadcast serial bus.

11. The system of claim 10 wherein said broadcast serial bus is a Controller Area Network (CAN).

12. The system of claim 1 further comprising a host control unit coupled to said network configured to receive illumination data from said sensor units.

13. The system of claim 12 wherein said host controller is configured to poll each said sensor unit to request illumination data from each of said sensors.

14. The system of claim 13 wherein said host controller is configured to enable a freeze mode of a sensor unit to prevent updating of illumination data during polling.

15. The system of claim 12 where said host controller is configured to compute the location of a predetermined illumination threshold and display a result to a user.

16. A method for detecting the aim of vehicle headlamps comprising the steps of:

providing a plurality of sensor units, each sensor unit comprising;

a microcontroller;

a plurality of photosensors arranged in a substantially linear array;

a memory storing program code, wherein execution of said program code by said microcontroller provides for the processing of data representing illumination of said plurality of photosensors;

a network interface, wherein each of said plurality of sensor units are coupled to a network through said network interface; and

wherein, each of said sensor units operate substantially independently from each other in said processing of said data;

positioning a vehicle a predetermined distance from said plurality of sensor units;

energizing a headlamp of said vehicle such that at least one of said plurality of sensor units is illuminated by said headlamp;

measuring an illumination level at each of said photosensors on said at least one of said sensor units.

17. The method of claim 16 wherein each sensor unit further comprises:

a plurality of operational amplifiers coupled to said plurality of photosensors;

an analog multiplexer;

an analog to digital converter;

wherein execution of said program code by said microcontroller further provides for the operation of said analog to digital converter to sample illumination levels at each of said plurality of said photosensors.

18. The method of claim 17 wherein execution of said program code by said microcontroller further provides for a time-domain smoothing of said illumination levels.

19. The method of claim 18 wherein said time-domain smoothing comprises an exponential decay algorithm.

20. The method of claim 17 wherein execution of said program code by said microcontroller further provides for spatial filtering of illumination data.

21. The method of claim 20 wherein said spatial filtering comprises a sliding window with multipliers for adjacent illumination values.

22. The method of claim 17 wherein execution of said program code by said microcontroller further provides for applying equalization correction to illumination data.

23. The method of claim 22 wherein each sensor unit further comprises:

an electrically erasable programmable read only memory (EEPROM) storing equalization information.

24. The method of claim 16 wherein each said sensor unit receives power over a network cable coupled to said network.

25. The method of claim 16 wherein said step of providing comprises providing four sensor units positioned at predetermined locations relative to said vehicle and wherein said network comprises a broadcast serial bus.

26. The method of claim 25 wherein said broadcast serial bus is a Controller Area Network (CAN).

27. The method of claim 16 wherein said step of providing further comprises providing a host control unit coupled to said network configured to receive illumination data from said sensor units.

28. The method of claim 27 wherein said host controller is configured to poll each said sensor unit to request illumination data from each of said sensors.

29. The method of claim 28 wherein said host controller is configured to enable a freeze mode of a sensor unit to prevent updating of illumination data during polling.

30. The method of claim 27 where said host controller is configured to compute the location of a predetermined illumination threshold and display a result to a user.