Vehicle soft impact detection

• US 7,303,041 B2
• Filed: 08/22/2005
• Issued: 12/04/2007
• Est. Priority Date: 08/22/2005
• Status: Active Grant

• Current Assignee: Littelfuse Incorporated
• Original Assignee: Key Safety Systems, Inc. (Ningbo Junsheng Investment Group Co., Ltd.)
• Inventors: Stuve, Steven R.
• Primary Examiner(s): Culbreth; Eric
• Assistant Examiner(s): ROCCA, JOSEPH M
• Application Number:
  US11/207,963
• Publication Number:
  US 20070039772A1
• Time in Patent Office: 834 Days
• Field of Search: 180/271, 180/274, 280/735, 701/45, 340/436, 293/4
• US Class Current: 180/274
• 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: B60R 21/34 Protecting non-occupants of a vehicle, e.g. pedestrians B60R19/02 takes precedence

Abstract

A vehicle soft impact detection system uses a piezo film mounted to a front vehicle bumper. The piezo film is selected and mounted to have a greater sensitivity to low-frequency shock waves as compared to high-frequency shock waves, the frequency and amplitude is then compared to a selected range of frequencies and amplitudes that are indicative of a crash with a soft tissue body. In a further embodiment the output of the piezo film is compared with the output of a second sensor which is more sensitive to high-frequency shock waves than to low-frequency shock waves such as a Terfenol-D based sensor.

Claims

1. A vehicle soft impact detection system for differentiating between an automobile front bumper impact with a rigid object and a front bumper impact with a pedestrian or animal, the system comprising:

a piezoelectric film sensor mounted to a front bumper in shock receiving relation;

a giant magnetostrictive sensing element mounted to the front bumper in shock receiving relation; and

a safety system in signal receiving relation to the piezoelectric film sensor, and to the giant magnetostrictive sensing element, the safety system in controlling relation to at least one device.

2. A method of differentiating an automobile front bumper impact with a pedestrian or animal from other types of impacts, comprising the steps of:

upon impact with an object, receiving a first signal from a piezoelectric film sensor mounted to the front bumper in shock receiving relation;

substantially simultaneously with receiving the first signal from the piezoelectric film sensor, receiving a second signal from a giant magnetostrictive sensing element which is mounted to the front bumper in shock receiving relation; and

comparing the first signal with the second signal to determine if an impact with a pedestrian or animal has occurred.

3. The method of claim 2 wherein the step of comparing the first signal with the second signal to determine if an impact with a pedestrian or animal has occurred, comprises:

determining from the first signal, a first amplitude at a frequency or range of frequencies below 1,000_Hz;

determining from the second signal, a second amplitude at a frequency or range of frequencies above 10,000 Hz; and

comparing the first amplitude with the second amplitude and determining if an impact with a pedestrian or animal has occurred.

4. The method of claim 2 wherein the step of comparing the first signal with the second signal comprises determining a ratio of relative signal strength, and comparing the first signal with at least two amplitude standards, and comparing the second signal with at least two amplitude standards.

5. A method of differentiating an automobile front bumper impact with a pedestrian or animal from other types of impacts, comprising the steps of:

upon impact with an object, receiving a first signal from a piezoelectric film sensor mounted to the front bumper in shock receiving relation;

substantially simultaneously with receiving the first signal from the piezoelectric film sensor, receiving a second signal from a second different type of sensor which is more responsive to high-frequency stress waves, where the second type of sensor is mounted to the front bumper in shock receiving relation;

comparing the first signal with the second signal to determine if an impact with a pedestrian or animal or another type of impact has occurred.

6. The method of claim 5 wherein the second different type of sensor is a giant magnetostrictive sensing element which is mounted in shock receiving relation to the front bumper.

7. The method of claim 5 wherein the step of comparing the first signal with the second signal to determine if an impact with a pedestrian or animal has occurred, comprises:

determining from the first signal, a first amplitude at a frequency or range of frequencies below 1,000₁₃ Hz;

determining from the second signal, a second amplitude at a frequency or range of frequencies above 10,000 Hz; and

comparing the first amplitude with the second amplitude, and determining if an impact with a pedestrian or animal has occurred.

8. The method of claim 5 wherein the step of comparing the first signal with the second signal includes determining a ratio of relative signal strength, and comparing the first signal with at least two amplitude standards, and comparing the second signal with at least two amplitude standards.