Patent Application
20080046147
The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
Referring to
A vehicle rollover event, as explained herein in connection with the present invention, may include side-to-side rotation of the vehicle 10 about the longitudinal axis, shown as the X-axis, of the vehicle 10, commonly referred to as “vehicle rollover,” or back-to-front rotation of the vehicle 10 about the vehicle lateral axis, shown as the Y-axis, commonly referred to as a “vehicle pitchover,” or a combination of rollover and pitchover. For purposes of describing the rollover event sensing of the present invention, the term “rollover” is generally used to refer to either a rollover event or a pitchover event. Additionally, an impact crash event may include a side impact crash event of the vehicle 10 along the lateral Y-axis, a frontal or rear impact crash event along the X-axis, or other impact crash events occurring along other sensing axes.
The vehicle crash sensing system 20 is designed to be located on the vehicle 10 to sense vehicle dynamics, particularly linear acceleration in a direction along a first sensing axis, and an angular rate (velocity) of the vehicle 10 about a second sensing axis. In the embodiments shown and described herein, the first sensing axis (e.g., Y-axis) is orthogonal to the second sensing axis (e.g., X-axis). However, linear acceleration and angular rate may be sensed in other first and second sensing axes according to other embodiments.
Included in the vehicle crash sensing system 20, according to the first embodiment, is a linear accelerometer 22, shown oriented on the vehicle 10 to sense linear acceleration AY along the lateral Y-axis. One example of a suitable linear accelerometer is Model No. ADXL78 commercially available from Analog Devices, Inc., rated at 50 g. Also included in vehicle crash sensing system 20 is an angular roll rate sensor 32 arranged, according to the first embodiment, on the vehicle 10 to sense angular roll rate about the longitudinal X-axis of the vehicle 10. One example of a suitable angular rate sensor is Model No. EWTZGC250, commercially available from Panasonic. The linear accelerometer 22 and angular roll rate sensor 32 may be located at any of a number of locations on the vehicle 10 to sense linear acceleration along the lateral Y-axis and angular rate about the longitudinal X-axis, respectively. According to some examples, the linear accelerometer 22 may be mounted in the vehicle passenger compartment, in a vehicle door or on a structural support of the vehicle 10, such as the A-pillar, B-pillar or C-pillar. The angular roll rate sensor 32 may be mounted in the vehicle passenger compartment near the center, according to one example, or elsewhere onboard the vehicle 10.
The liner accelerometer 22 and angular roll rate sensor 32 are integrated into a single vehicle crash sensing system 20 to sense either or both of a side impact crash event and a rollover event according to the embodiment shown and described herein. The vehicle crash sensing system 20 employs the linear accelerometer 22 to generate a linear acceleration AY that is employed both by a side crash event algorithm 50 and a rollover crash event algorithm 70. The vehicle crash sensing system 20 therefore employs the linear accelerometer 20 in a manner that allows for sensing multiple crash events, thereby eliminating the need for separate and distinct acceleration sensors.
The vehicle crash sensing system 20 has a controller, shown as a microprocessor control unit (MCU) 25, having a microprocessor 24 and memory 34. Stored within memory 34 are the side crash event algorithm 50 and rollover crash event algorithm 70. The microprocessor 24 may include any known analog and/or digital processing circuitry capable of executing the side crash event algorithm 50 and rollover crash event algorithm 70. Memory 34 may include conventional memory storage medium such as electrically erasable programmable read-only memory (EEPROM) or random access memory (RAM) that may store various program calibrations and routines for performing the crash sensing detection. The MCU 25 may be a dedicated crash sensing controller or may be implemented on a shared controller.
The vehicle crash sensing system 20 senses a linear impact crash event, such as a side crash event, by processing the linear acceleration signal AY output from the linear accelerometer 22. For a side impact event, the linear accelerometer 22 is oriented along the lateral Y-axis of the vehicle 10. The output of the linear accelerometer 22 is shown input to the side crash event algorithm 50. Any of a number of side crash event algorithms 50 may be employed to sense the presence of a side impact crash event. One example of a side crash event algorithm 50 is shown in
The crash sensing system 20 employs signal conditioning circuitry 26 for processing the sensed acceleration signal AY output from the linear accelerometer 22 and outputs a processed linear acceleration signal to the rollover crash event algorithm 70. The signal conditioning circuitry 26 enables the use of a single accelerometer 22 that is generally configured for use to detect a side impact crash event to also be employed to detect a vehicle rollover crash event, according to one embodiment of the present invention. The signal conditioning circuitry 26 processes the linear acceleration signal output to alter the range, resolution and/or bandwidth of the inertial linear acceleration sensor 22 used for the side impact crash event in order to provide linear acceleration data that meets the requirements for sensing a second crash-type event, namely a vehicle rollover event. The signal conditioning circuitry 26 therefore allows for elimination of duplicative sensors by generating the appropriately processed linear acceleration signal.
The signal conditioning circuitry 26 is shown including an amplifier 28 coupled to the output of linear accelerometer 22, and a band-pass filter 26 coupled to the output of the amplifier 28. The amplifier 28 amplifies the sensed linear acceleration signal AY by an amplification gain, such as 10× according to one example. The band-pass filter 30 has a pass band, such as a frequency range of 0.1 Hz to 50 Hz, according to one embodiment. According to another embodiment, the band-pass filter 30 may have the low frequency portion of the signal removed by the subtraction of the output of a linear integration function tracking the low band portion of the signal. The band-pass filter 30 therefore filters low frequencies below 0.1 Hz and high frequencies above 50 Hz, according to this embodiment, to reduce or eliminate noise. The amplified and filtered linear acceleration signal is then input to the rollover crash event algorithm 70.
The digital signal conditioning circuitry 26 may be implemented in analog circuitry, according to one embodiment. According to another embodiment, the signal conditioning circuitry 26 may be implemented in digital circuitry. According to other embodiments, a combination of analog and digital circuitry may be employed in the signal conditioning circuitry 26 to process the sensed linear acceleration signal AY and make the processed linear acceleration signal available as an input to the rollover crash event algorithm 70.
The vehicle crash sensing system 20 further includes an angular roll rate sensor 32 for sensing angular rate (velocity) {dot over (φ)}X of the vehicle 10 about a second sensing axis. In the embodiment shown, the angular roll rate sensor 32 is oriented to sense angular rate about the longitudinal X-axis of the vehicle 10, and generates a sensed angular rate signal {dot over (φ)}X indicative thereof. Any of a number of angular rate sensors 32 may be employed to sense the vehicle angular roll rate {dot over (φ)}X. Angular roll rate sensor 32 may be oriented about another sensing axis, such as the lateral Y-axis to determine a pitch rate of the vehicle 10.
The rollover crash event algorithm 34 therefore receives as inputs the processed linear acceleration signal and the sensed angular roll rate signal. The rollover crash event algorithm 70 processes the linear acceleration and angular rate signals and determines an anticipated or actual rollover of the vehicle 10 about the longitudinal X-axis. According to other embodiments, the rollover crash event algorithm 70 may determine a rollover event of the vehicle 10 about other axes, such as the lateral Y-axis, also referred to as a pitchover event. Any of a number of rollover crash event algorithms may be employed. One example of a rollover crash event algorithm 70 is shown in
Referring to
It should be appreciated that the first and second linear accelerometers 40 and 42 in the system 20 according to the second embodiment advantageously sense linear accelerations A1 and A2 about the two separate axes. By orienting the first and second linear accelerometers 40 and 42 at angles θ=−45° and θ=+45°, respectively, such that the corresponding sensing axes are offset from both the longitudinal X-axis and lateral Y-axis of the vehicle 10, each of the linear accelerometer sensors 40 and 42 provide a longitudinal X-axis acceleration component AX and a lateral Y-axis acceleration component AY. According to one example, the accelerometers 40 and 42 may include an integrated dual axis accelerometer, such as Model No. ADXL278, commercially available from Analog Devices, Inc.
The vehicle crash sensing system 20 according to the second embodiment employs signal processing circuitry 26 that includes an arithmetic logic device 44, such as a summer or a subtractor for either summing or subtracting the sensed linear acceleration signals A1 and A2 output from the first and second linear accelerometers 40 and 42. According to the embodiment shown, the sensed linear acceleration signals from each of the first and second linear accelerometers 40 and 42 are subtracted such that the difference provides a signal indicative of the lateral acceleration in the Y-axis. The arithmetically summed output of the sensed acceleration signals A1 and A2 provides the lateral Y-axis linear acceleration component that is input to a side crash event algorithm 50 for processing as discussed above.
The signal processing circuitry 26 in the vehicle crash sensing system 10 according to the second embodiment further employs an amplifier 28 for amplifying arithmetic summed linear acceleration signal, and a band-pass filter 30 for filtering amplified linear acceleration signals. The amplified and filtered linear acceleration signal is then input to a rollover crash event algorithm 70. Additionally, an angular roll rate signal {dot over (φ)}X sensed by angular roll rate sensor 32 oriented to sense angular acceleration about the longitudinal X-axis is also input to the rollover crash events algorithm 70 and is processed as discussed above in connection with the first embodiment.
The vehicle crash sensing system 20 according to the second embodiment is shown employing two linear accelerometers 40 and 42 each rated as 50 g acceleration sensors that produce the equivalent of a single axis 5 g acceleration sensor, according to one example. The amplification gain provided by the amplifier 28 is of a different magnitude (e.g., 7×) from that of the first embodiment, due to the magnitude of the summing vector acceleration components AX and AY from the two contributing linear accelerometers 40 and 42. The band-pass filter 30 may have a pass band frequency range from 0.1 Hz to 50 Hz, according to one embodiment.
It should be appreciated that the two linear accelerometers 40 and 42 also provide the linear acceleration AX along the longitudinal X-axis, which may be processed by the MCU 25 for additional crash event detection or other purposes. The vehicle crash sensing system 20 may employ additional sensors that may be processed by the same or different crash algorithms that detect any of a number of crash events of the vehicle 10.
Referring to
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It should be appreciated that the side crash event algorithm 50 and rollover crash event algorithm 70 may be processed by the same or different MCU 25 or other analog and/or digital circuitry by executing software code as should be evident to those skilled in the art. The MCU 25 may be part of a dedicated controller or may be a shared controller within the vehicle 10. Additionally, one or more outputs of the MCU 25 generally provides output signal(s) that may be made available to various restraint devices and other devices that may utilize a crash event indicative signal.
The vehicle crash sensing system 20 according to the present invention advantageously integrates the use of a linear accelerometer signal in a crash sensing system 20 to enable sensing of multiple crash events. In particular, a linear accelerometer is employed to sense a crash event and a rollover event of a vehicle by employing signal processing circuitry so as to eliminate the need for separate and distinct acceleration sensors, thereby eliminating duplication and reducing the cost of the overall crash sensing system 20.
It will be understood by those who practice the invention and those skilled in the art, that various modifications and improvements may be made to the invention without departing from the spirit of the disclosed concept. The scope of protection afforded is to be determined by the claims and by the breadth of interpretation allowed by law.
