Diagnostics for vehicle deformation sensor system

• US 6,204,756 B1
• Filed: 10/23/1998
• Issued: 03/20/2001
• Est. Priority Date: 10/23/1998
• Status: Expired due to Fees

• Current Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Original Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Inventors: Zoratti, Paul, Senyk, Myron Ihor
• Primary Examiner(s): Lefkowitz, Edward
• Assistant Examiner(s): GOINS, DAVETTA WOODS
• Application Number:
  US09/178,108
• Time in Patent Office: 879 Days
• Field of Search: 340/438, 340/436, 340/435, 340/596, 340/437, 340/665, 702/141, 702/145, 280/735, 280/734, 200/DIG.10, 180/274, 701/45, 310/311, 310/314
• US Class Current: 340/438
• CPC Class Codes: B60R 2021/01027 Safing sensors
• CPC Class Codes: B60R 21/0136 responsive to actual contact with an obstacle , e.g. to vehicle deformation, bumper displacement or bumper velocity relative to the vehicle monitoring crash strength in combination with passenger seat detection B60R21/01558
• CPC Class Codes: G01P 15/0891 with indication of predetermined acceleration values G01P15/135 takes precedence
• CPC Class Codes: G01P 15/0907 of the compression mode type

Abstract

A sensor system for detecting impacts to a vehicle, including diagnostics for monitoring the sensor system. The sensor system includes one or more piezoelectric sensor assemblies (42), each including a coaxial piezoelectric cable (44) contained within a tube housing (54), which is mounted to a structural member of the vehicle. The sensor system may also include accelerometers (36, 38) that are also in communication with the restraints control module (40) and employed in combination with one or more piezoelectric sensor assemblies (42). Further, the sensor system includes diagnostics for monitoring one or more of the sensor assemblies (42) in order to detect a sensor failure, while not interfering with the impact signals from the sensor assemblies (42).

Claims

1. A method of diagnosing a malfunction in an impact sensor including a multilayer piezoelectric cable mounted along a component in a vehicle, the method comprising the steps of:

generating a first diagnostic signal having a predetermined voltage and frequency;

transmitting the first signal to a first location of the piezoelectric cable;

capacitively receiving a second diagnostic signal at a second location on the piezoelectric cable, spaced from the first location;

transmitting the second diagnostic signal to a controller; and

analyzing the second diagnostic signal in the controller.

2. The method of claim 1 wherein the piezoelectric cable is a coaxial piezoelectric cable and the first location is a copper shield of the sensor cable.

3. The method of claim 2 wherein the piezoelectric cable is a coaxial piezoelectric cable and the second location is a center conductor of the piezoelectric cable.

4. The method of claim 3 further including the steps of:

generating an impact signal in the piezoelectric cable;

communicating the impact signal simultaneously with the second diagnostic signal to the controller; and

from the impact signal in the controller.

5. The method of claim 1 further including the steps of:

generating an impact signal in the piezoelectric cable;

communicating the impact signal simultaneously with the second diagnostic signal to the controller; and

monitoring the second diagnostic signal apart from the impact signal in the controller.

6. The method of claim 1 wherein the first diagnostic signal is produced at a predetermined voltage between about three to eight volts, at a predetermined frequency less than about twenty hertz.

7. The method of claim 6 wherein the second diagnostic signal, when operating without malfunction, is a predetermined voltage between about 100 to 300 millivolts, at a predetermined frequency less than about twenty hertz.

8. A method of diagnosing a malfunction in an impact sensor including a coaxial piezoelectric cable mounted along a component in a vehicle, the method comprising the steps of:

generating a first diagnostic signal having a predetermined voltage and frequency;

transmitting the first signal to a first location of the piezoelectric cable;

capacitively receiving a second diagnostic signal at a second location on the coaxial cable, spaced from the first location;

transmitting the second diagnostic signal to a controller;

analyzing the second diagnostic signal in the controller;

generating an impact signal in the piezoelectric cable;

communicating the impact signal simultaneously with the second diagnostic signal to the controller; and

monitoring the second diagnostic signal apart from the impact signal in the controller.

9. A diagnostics system for diagnosing a malfunction in an impact sensor mounted in a vehicle comprising:

a coaxial piezoelectric cable mounted along a component in a vehicle;

means for generating a first diagnostic signal having a predetermined voltage and frequency;

means for transmitting the first signal to a first location of the piezoelectric cable;

means for capacitively receiving a second diagnostic signal at a second location on the coaxial cable, spaced from the first location;

a controller for receiving the second diagnostic signal; and

means for analyzing the second diagnostic signal.

10. The diagnostic system of claim 9 further comprising:

means for generating an impact signal in the piezoelectric cable;

means for communicating the impact signal simultaneously with the second diagnostic signal to the controller; and

means for monitoring the second diagnostic signal apart from the impact signal.