Non-contact obstacle detection system utilizing ultra sensitive capacitive sensing

• US 20030071727A1
• Filed: 05/10/2002
• Published: 04/17/2003
• Est. Priority Date: 10/17/2001
• Status: Active Grant

• Current Assignee: Strattec Power Access LLC (Strattec Security Corporation)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Deplae, Brian, Pasiecznik, John Jr., Haag, Ronald Helmut, Husic, Jeremy M.
• Granted Patent: US 6,750,624 B2
• Time in Patent Office: Days
• US Class Current: 340/562
• CPC Class Codes: E05F 15/46 responsive to changes in electrical capacitance
• CPC Class Codes: E05Y 2400/452 for saving energy
• CPC Class Codes: E05Y 2600/40 Mounting location; Visibility of the elements
• CPC Class Codes: E05Y 2900/548 Trunk lids
• CPC Class Codes: H03K 17/955 using a capacitive detector
• CPC Class Codes: H03K 2017/9602 characterised by the type or shape of the sensing electrodes
• CPC Class Codes: H03K 2217/96078 Sensor being a wire or a strip, e.g. used in automobile door handles or bumpers

Abstract

A non-contact obstacle detection system utilizing ultra sensitive capacitive techniques. In an exemplary embodiment, the system includes a sensing element disposed in proximity to a moveable panel and a proximity detection circuit in communication with the sensing element. The proximity detection circuit generates a differential output signal reflective of whether a foreign object is in proximity to the sensing element. In addition, a central control module is in communication with the sensing element. The central control module determines whether the differential output signal is reflective of a foreign object in proximity to the sensing element. If the central control module determines that the differential output signal is reflective of a foreign object in proximity to the sensing element, and the moveable panel is moving toward a closed position, then the central control module generates a control output signal to stop the moveable panel from moving toward the closed position.

Claims

1. An obstacle detection system, comprising:

a sensing element disposed in proximity to a moveable panel;

a proximity detection circuit in communication with said sensing element, said proximity detection circuit generating a differential output signal reflective of whether a foreign object is in proximity to said sensing element; and

a central control module in communication with said sensing element, said central control module determining whether said differential output signal is reflective of a foreign object in proximity to said sensing element;

wherein, if said central control module determines that said differential output signal is reflective of a foreign object in proximity to said sensing element, and said moveable panel is moving toward a closed position, then said central control module generates a control output signal to stop said moveable panel from moving toward said closed position.

2. The obstacle detection system of claim 1, wherein said sensing element further comprises a capacitive sensing element having a nominal capacitance.

3. The obstacle detection system of claim 2, wherein said proximity detection circuit detects a change in said nominal capacitance as a result of a foreign object in proximity to said sensing element.

4. The obstacle detection system of claim 3, wherein said proximity detection circuit is integrated within said sensing element.

5. The obstacle detection system of claim 2, wherein said proximity detection circuit further comprises:

a first oscillator which generates a first frequency signal, said first frequency signal dependent upon the capacitance of said sensing element; and

a second oscillator which generates a reference frequency signal;

wherein said differential output signal is determined from a comparison between said first frequency signal and said reference frequency signal.

6. The obstacle detection system of claim 1, further comprising:

a coaxial cable coupling said proximity detection circuit and said central control module, said coaxial cable transmitting both a DC power signal and said differential output signal.

7. The obstacle detection system of claim 6, wherein both said proximity detection circuit and said central control module further comprise a bias “

T”

apparatus included therewith.

8. The obstacle detection system of claim 6, wherein said differential output signal has a frequency range of about 0 Hz to about 15 MHz.

9. The obstacle detection system of claim 6, wherein said first frequency signal and said reference frequency signal are generated at a frequency of at least 900 MHz.

10. The obstacle detection system of claim 5, wherein said central control module further comprises:

a microprocessor; and

software for comparing said differential output signal to a nominal value, said nominal value depending upon a specific position of said moveable panel.

11. An obstacle detection system, comprising:

at least one sensing element disposed in proximity to a moveable panel;

a proximity detection circuit in communication with each said at least one sensing element, each said proximity detection circuit generating a differential output signal reflective of whether a foreign object is in proximity to said at least one sensing element corresponding thereto;

a central control module in communication with each said sensing element, said central control module determining whether each said differential output signal is reflective of a foreign object in proximity to said at least one sensing element;

wherein, if said central control module determines that said differential output signal is reflective of a foreign object in proximity to said at least one sensing element, and said moveable panel is moving toward a closed position, then said central control module generates a control output signal to stop said moveable panel from moving toward said closed position.

12. The obstacle detection system of claim 11, wherein each said at least one sensing element further comprises a capacitive sensing element having a nominal capacitance.

13. The obstacle detection system of claim 12, wherein each said proximity detection circuit detects a change in said nominal capacitance as a result of a foreign object in proximity to said at least one sensing element corresponding thereto.

14. The obstacle detection system of claim 13, wherein each said proximity detection circuit is integrated within said at least one sensing element corresponding thereto.

15. The obstacle detection system of claim 12, wherein each said proximity detection circuit further comprises:

a first oscillator which generates a first frequency signal, said first frequency signal dependent upon the capacitance of said at least one sensing element corresponding thereto; and

a second oscillator which generates a reference frequency signal;

wherein said differential output signal is determined from a comparison between said first frequency signal and said reference frequency signal.

16. The obstacle detection system of claim 11, further comprising:

a coaxial cable coupling each said proximity detection circuit with said central control module, each said coaxial cable transmitting both a DC power signal and said differential output signal.

17. The obstacle detection system of claim 16, wherein each said proximity detection circuit and said central control module further comprise a bias “

T”

apparatus included therewith.

18. The obstacle detection system of claim 16, wherein:

said differential output signal has a frequency range of about 0 Hz to about 15 MHz; and

said first frequency signal and said reference frequency signal are generated at a frequency of at least 900 MHz.

19. The obstacle detection system of claim 15, wherein said central control module further comprises:

a microprocessor;

a multiplexer for selectively passing a selected differential output signal from each differential output signal inputted to said multiplexer; and

software for comparing said selected differential output signal to a nominal value, said nominal value depending upon a specific position of said moveable panel.

20. The obstacle detection system of claim 11, further comprising:

a power door control module in communication with said central control module, said power door control module controlling the movement of said moveable panel.

21. An obstacle detection system for a vehicle, comprising:

a moveable panel;

a sensing element disposed in proximity to said moveable panel;

a proximity detection circuit in communication with said sensing element, said proximity detection circuit generating a differential output signal reflective of whether a foreign object is in proximity to said sensing element; and

a central control module in communication with said sensing element, said central control module determining whether said differential output signal is reflective of a foreign object in proximity to said sensing element;

wherein, if said central control module determines that said differential output signal is reflective of a foreign object in proximity to said sensing element, and said moveable panel is moving toward a closed position, then said central control module generates a control output signal to stop said moveable panel from moving toward said closed position.

22. The obstacle detection system of claim 21, wherein said sensing element further comprises a capacitive sensing element having a nominal capacitance.

23. The obstacle detection system of claim 22, wherein said proximity detection circuit detects a change in said nominal capacitance as a result of a foreign object in proximity to said sensing element.

24. The obstacle detection system of claim 23, wherein said proximity detection circuit is integrated within said sensing element.

25. The obstacle detection system of claim 22, wherein said proximity detection circuit further comprises:

a first oscillator which generates a first frequency signal, said first frequency signal dependent upon the capacitance of said sensing element; and

a second oscillator which generates a reference frequency signal;

wherein said differential output signal is determined from a comparison between said first frequency signal and said reference frequency signal.

26. The obstacle detection system of claim 21, further comprising:

a coaxial cable coupling said proximity detection circuit and said central control module, said coaxial cable transmitting both a DC power signal and said differential output signal.

27. The obstacle detection system of claim 26, wherein both said proximity detection circuit and said central control module further comprise a bias “

T”

apparatus included therewith.

28. The obstacle detection system of claim 26, wherein said differential output signal has a frequency range of about 0 Hz to about 15 MHz.

29. The obstacle detection system of claim 26, wherein said first frequency signal and said reference frequency signal are generated at a frequency of at least 900 MHz.

30. The obstacle detection system of claim 25, wherein said central control module further comprises:

a microprocessor; and

software for comparing said differential output signal to a nominal value, said nominal value depending upon a specific position of said moveable panel.

31. The obstacle detection system of claim 30, wherein said software further includes a floating variable routine for compensating for environmental changes and structural changes proximate said moveable panel.

32. The obstacle detection system of claim 31, wherein said floating variable routine further comprises a global float routine and a position float routine, said global float routine being responsive to environmental changes and said position float routine being responsive to positional changes of said moveable panel.

33. The obstacle detection system of claim 32, wherein said global float routine further includes a global float counter, said global float counter preventing a change in a given global float value until such time as said global float counter has reached a determined value.