Apparatus and method for diagnostics of a capacitive sensor

• US 9,791,494 B2
• Filed: 01/08/2013
• Issued: 10/17/2017
• Est. Priority Date: 01/20/2012
• Status: Active Grant

• Current Assignee: Lear Corporation
• Original Assignee: Lear Corporation
• Inventors: Deumal Herraiz, Marc, Castillo-Vazquez, Laura, Ferre Fabregas, Antoni
• Primary Examiner(s): Hollington, Jermele M
• Assistant Examiner(s): RHODES-VIVOUR, TEMILADE S
• Application Number:
  US13/736,303
• Publication Number:
  US 20130187664A1
• Time in Patent Office: 1,743 Days
• Field of Search: 324548
• CPC Class Codes: G01D 1/00 Measuring arrangements giving results other than momentary value of variable, of general application G01D3/00 takes precedence; in tariff metering apparatus G01D4/00; transducers not specially adapted for a specific variable G01D5/00
• CPC Class Codes: G01D 18/00 Testing or calibrating apparatus or arrangements provided for in groups G01D1/00 - G01D15/00
• CPC Class Codes: G01D 2218/10 Testing of sensors or measuring arrangements
• CPC Class Codes: G01D 5/24 by varying capacitance
• CPC Class Codes: G01R 1/00 Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00 constructional details particular to electromechanical arrangements for measuring the electric consumption G01R11/02
• CPC Class Codes: G01R 31/2829 Testing of circuits in sensor or actuator systems testing of apparatus for measuring electric or magnetic variables G01R35/00; testing of indicating or recording apparatus G01D; in airbag systems B60R21/0173; checking gas analysers G01N33/007; monitoring or fail-safe circuits for electromagnets H01F7/1844
• CPC Class Codes: G01R 31/64 Testing of capacitors
• CPC Class Codes: G06F 2101/00 Indexing scheme relating to the type of digital function generated

Abstract

In at least one embodiment, an apparatus for diagnosing a state of a capacitive sensor is provided. The apparatus includes a control unit for being operably coupled to a decoupling device that exhibits a drift condition and to the capacitive sensor. The control unit being configured to determine an impedance of the capacitive sensor and to determine a characteristic of the capacitive sensor based on at least the impedance. The control unit being further configured to determine a characteristic of the decoupling device based on the characteristic of the capacitive sensor and to provide an estimated capacitance based on the characteristic of the decoupling device, the estimated capacitance being indicative of the state of the capacitive sensor.

Claims

1. An apparatus for diagnosing a state of a capacitive sensor, the apparatus comprising:

a control unit for being operably coupled to a capacitor that exhibits a drift condition and to the capacitive sensor, the control unit being configured to;

determine an impedance of the capacitive sensor;

determine a resistance of the capacitive sensor based on at least the impedance;

determine a characteristic of the capacitor based on the resistance of the capacitive sensor; and

provide an estimated capacitance based on the characteristic of the capacitor, the estimated capacitance being indicative of the capacitive sensor exhibiting a fault condition.

2. The apparatus of claim 1 wherein the resistance of the capacitive sensor corresponds to a minimum resistance value of the capacitive sensor.

3. The apparatus of claim 1 wherein the characteristic of the capacitor corresponds to a capacitance of the capacitor.

4. The apparatus of claim 1 wherein the characteristic of the capacitive sensor and the characteristic of the capacitor compensate for the drift condition exhibited at the capacitor.

5. The apparatus of claim 1 wherein the control unit is further configured to compare the estimated capacitance to a predetermined capacitance value to diagnose the capacitive sensor.

6. The apparatus of claim 5 wherein the control unit is further configured to determine that the capacitive sensor exhibits the fault condition in response to the estimated capacitive exceeding the predetermined capacitance value.

7. A method for diagnosing a state of a capacitive sensor, the method comprising:

determining an impedance of the capacitive sensor;

determining a resistance of the capacitive sensor based on at least the impedance;

determining a characteristic of a capacitor that exhibits a drift condition based on the resistance of the capacitive sensor; and

providing an estimated capacitance based on the characteristic of the capacitor, the estimated capacitance being of the capacitive sensor exhibiting a fault condition.

8. The method of claim 7 wherein the resistance of the capacitive sensor corresponds to a minimum resistance value of the capacitive sensor.

9. The method of claim 7 wherein the characteristic of the capacitor corresponds to a capacitance of the capacitor.

10. The method of claim 7 further comprising compensating for the drift condition exhibited at the capacitor with the resistance of the capacitive sensor and the characteristic of the capacitor.

11. The method of claim 7 further comprising comparing the estimated capacitance to a predetermined capacitance value to diagnose the capacitive sensor.

12. The method of claim 11 further comprising determining that the capacitive sensor exhibits the fault condition in response to the estimated capacitive exceeding the predetermined capacitance value.

13. An apparatus for diagnosing a state of a capacitive sensor, the apparatus comprising:

a control unit for being operably coupled to a capacitor and the capacitive sensor, the capacitor exhibiting a drift condition and being configured to prevent a transfer of energy to the capacitive sensor, the control unit being configured to;

determine an impedance of the capacitive sensor;

determine a resistance of the capacitive sensor based on at least the impedance;

determine a characteristic of the capacitor based on the resistance of the capacitive sensor; and

provide an estimated capacitance based on the characteristic of the capacitor, the estimated capacitance being indicative of the capacitive sensor exhibiting a fault condition.

14. The apparatus of claim 13 wherein the resistance of the capacitive sensor corresponds to a minimum resistance value of the capacitive sensor.

15. The apparatus of claim 13 wherein the characteristic of the capacitor corresponds to a capacitance of the capacitor.

16. The apparatus of claim 13 wherein the characteristic of the capacitive sensor and the characteristic of the capacitor compensate for the drift condition exhibited at the capacitor.

17. The apparatus of claim 13 wherein the control unit is further configured to compare the estimated capacitance to a predetermined capacitance value to diagnose the capacitive sensor.