Vehicle soft impact detection

• US 20070039772A1
• Filed: 08/22/2005
• Published: 02/22/2007
• 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
• Granted Patent: US 7,303,041 B2
• Time in Patent Office: Days
• 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 piezo film sensor mounted in shock receiving relation to a front bumper;

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

a safety system in signal receiving relation to the piezo 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 piezo film sensor mounted in shock receiving relation to the front bumper;

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

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 piezo film sensor mounted in shock receiving relation to the front bumper;

substantially simultaneously with receiving the first signal from the piezo 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 in shock receiving relation to the front bumper;

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 1,000 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.

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.

9. 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 signal from a piezo film sensor mounted in shock receiving relation to the front bumper;

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

determining the signal amplitude at a frequency or range of frequencies below 2,000 Hz;

comparing the amplitude of the signal at the frequency or range of frequencies below 2,000 Hz with the signal amplitude at a frequency or range of frequencies above 10,000 Hz to determine if an impact with a pedestrian or animal has occurred.

10. The method of claim 9 wherein the step of determining the signal amplitude at a frequency or range of frequencies below 2,000 Hz comprises determining the signal amplitude at a frequency or range of frequencies below 1,000 Hz, and the step of comparing the amplitude of the signal at the frequency or range of frequencies below 2,000 Hz with the signal amplitude at a frequency or range of frequencies above 10,000 Hz comprises comparing the amplitude of the signal at the frequency or range of frequencies below 1,000 Hz with the signal amplitude at a frequency or range of frequencies above 10,000 Hz.