Smart airbag for vehicular applications

A smart airbag (14) is monitored by a vehicle restraint control module (24) and includes a state sensor (42) that generates an airbag state signal. A smart airbag fault circuit (40) is coupled to the state sensor (42) and includes multiple state devices (50). Each of the state devices (50) has a characteristic that is indicative of the state of the smart airbag (14). The state devices (50) are configured to be monitored by the vehicle restraint control module (24). A smart airbag state monitor (44) is separate from the vehicle restraint control module (24), is coupled to the state devices (50), and alters the state in response to the airbag state signal.

TECHNICAL FIELD

The present invention relates to vehicle safety restraint systems and more particularly, to a system and method of indicating diagnostic information related to a smart airbag.

BACKGROUND OF THE INVENTION

Restraints are utilized within automotive vehicles to prevent injury to vehicle occupants in the event of a collision. Various types of restraints are utilized, which may be active or passive in design. Some example active restraints are airbags, pretensioners, and load limiting seat belts. Some example passive restraints are seat belts, headrests, and energy absorbing material containing devices.

To satisfy various automobile safety requirements, such as the requirements under the Federal Motor Vehicle Safety Standard (FMVSS) 208, automobile manufacturers are required to include “Smart” airbag systems in their vehicles. Smart airbag systems refer to airbag systems that are capable of protecting occupants with different occupant characteristics, such as size, weight, and position within a vehicle seat. These requirements also require the prevention of airbag deployment when unwarranted. For example, it is undesirable to deploy an airbag into a rearward facing child seat or when a vehicle occupant is positioned too close to the airbag. To determine occupant characteristics, sensors, such as vehicle interior cameras and seat-based sensors, have been utilized. Such occupant characteristic sensors are considered impractical for certain applications and tend to complicate a restraint control circuit.

As an alternative to the use of occupant characteristic or classification sensors, airbag internal sensors are currently being introduced for determining the state of an airbag including the deployment characteristics thereof. Occupant characteristic information can be obtained or derived from the deployment characteristics. For example, by monitoring the deployed pressure of an airbag one can determine whether the airbag has collided with an object, such as a child seat. When the airbag collides with the child seat an uncharacteristical deployment pressure transient results as compared to a normal deployment defined as when the airbag is deployed without object intervention. A restraint controller may react in response to the uncharacteristical transient to prevent further expansion of the airbag.

Airbags with internal sensors are considered smart airbags. Smart airbags are distinguishable from smart airbag systems. Smart airbags are capable of determining a current state of an airbag whereas smart airbag systems are capable of altering the manner in which an airbag is deployed, depending on occupant determined characteristics.

There is a desire for traditional style airbags to be replaced with smart airbags and in addition that the introduction of the smart airbags not require changes to the traditional style restraint control systems or to the logic of any restraint controllers therein. It is also desired that upon the introduction of the smart airbags that existing restraint controllers be capable of determining when a fault exists with the smart airbag. A fault may include a static physical fault, such as one with a connector, a wire, and a trigger, as well as a dynamic physical fault, such as an uncharacteristical deployment condition.

Thus, there exists a need for a smart airbag that may be utilized in replacement of a traditional style airbag that does not require alteration to a corresponding restraint control system and that provides an indication to a restraint controller when a fault exists.

SUMMARY OF THE INVENTION

The present invention provides a smart airbag that is monitored by a vehicle restraint control module. The smart airbag includes a state sensor that generates an airbag state signal. A smart airbag fault circuit is coupled to the state sensor and includes multiple state devices. Each of the state devices has a characteristic that is indicative of the state of the smart airbag. The state devices are configured to be monitored by the vehicle restraint control module. A smart airbag state monitor is separate from the vehicle restraint control module, is coupled to the state devices, and alters the state in response to the airbag state signal.

The embodiments of the present invention provide several advantages. One such advantage is the provision of a smart airbag that is capable of within and of itself detecting a fault therein including an uncharacteristic deployment transient.

Another advantage provided by an embodiment of the present invention is the provision of a smart airbag that may be used in replacement of traditional airbags within traditional restraint control systems and smart airbag systems without the reconfiguring or reprogramming of the stated systems.

Yet another advantage provided by an embodiment of the present invention is the provision of allowing a restraint controller to detect a fault within the smart airbag without communication between the smart airbag and the restraint controller. In addition, the present invention prevents the deployment or further expansion of the airbag when a fault exists as appropriate.

The present invention itself, together with attendant advantages, will be best understood by reference to the following detailed description, taken in conjunction with the accompanying figures.

DETAILED DESCRIPTION

In the following figures, the same reference numerals will be used to refer to the same components. While the present invention is described with respect to a system and method of indicating diagnostic information related to a smart airbag, the present invention may be adapted to be used in various applications and systems including: collision warning systems, collision avoidance systems, parking-aid systems, reversing-aid systems, passive countermeasure systems, adaptive cruise control systems, lane departure systems, lane-keeping systems, windshield clearing systems, or other systems known in the art. The present invention may be used to supplement a pre-collision sensing system.

In the following description, various operating parameters and components are described for multiple constructed embodiments. These specific parameters and components are included as examples and are not meant to be limiting.

Additionally, in the following description, the term “performing” may include activating, deploying, initiating, powering, and other terms known in the art that may describe the manner in which a countermeasure or a comfort and convenience feature may be operated.

As well, in the following description, various countermeasures are discussed. The countermeasures may be reversible or irreversible. Reversible countermeasures refer to countermeasures that may be reset to their original form or used repeatedly without a significant amount of functional deficiency, which may be determined by a system designer. Irreversible countermeasures refer to countermeasures such as airbags that, once deployed, are not reusable.

Furthermore, a countermeasure signal may include information pertaining to the above-stated reversible and irreversible countermeasures or may include other information, such as collision warning information, and parking-aid or reversing-aid countermeasure information. For example, the countermeasure signal may contain object detection information, which may be used to indicate to a vehicle operator the presence or close proximity of a detected object.

In addition, the term “object” may refer to any animate or inanimate object. An object may be a vehicle, a pedestrian, a lane marker, a road sign, a roadway lane designating line, a vehicle occupant, window moisture, or other object known in the art.

Referring now toFIG. 1, a block diagrammatic view of a collision warning and countermeasure system10for a vehicle12incorporating a smart airbag14in accordance with an embodiment of the present invention is shown. The countermeasure system10includes object detection sensors16, occupant classification sensors18, countermeasures20, and a smart airbag system22. The countermeasure system10detects objects within proximity of the vehicle12and any collision therewith via the object detection sensors16. The countermeasure system10detects occupant characteristics of occupants within the vehicle12via the occupant classification sensors18. The countermeasure system10in response to the threat of the detected objects and the occupant characteristics may perform one or more of the countermeasures20.

In performing the countermeasure20, the smart airbag system22may include (as shown inFIG. 2) and be utilized to activate the smart airbag14in response to a collision or potential collision with one or more of the detected objects. The smart airbag14includes circuitry, which allows a restraint control module24to detect when a fault exists with the smart airbag14. The circuitry is shown and described in detail with respect to the embodiment ofFIG. 2. The restraint control module24may indicate the fault via the indicator26. The restraint control module24may refrain from activating the smart airbag14depending upon any faults existing with the smart airbag14and the occupant characteristics.

The object detection sensors16monitor an environment exterior to the vehicle12and generate object detection signals upon detection of an object. The occupant classification sensors18monitor interior areas of the vehicle12and generate occupant classification signals in response to the presence and characteristics of occupants therein. The occupant characteristics may include occupant positioning within a seat, occupant size, shape, weight, whether a seat belt is utilized, or other known occupant characteristics. The occupant classification sensors18may also detect whether a child safety seat is located within a passenger seat of the vehicle12.

The object detection sensors16and the occupant classification sensors18may be infrared, vision, ultrasonic, radar, or lidar based or may be in the form of an accelerometer, a piezo electric sensor, a piezo resistive sensor, a charged-coupled device, a series of photodiodes, or in some other form known in the art. The object detection sensors may sense characteristics of an environment external to the vehicle or internal to the vehicle. For example radar sensors may be used to detect an external environment whereas accelerometers may be used to detect an internal environment. The object detection sensors16and the occupant classification sensors18may also be in the form of a pressure sensor or a strain gage. The object detection sensors16and the occupant classification sensors18may be in various locations on the vehicle.

The countermeasures20include passive countermeasures28and active countermeasures30. The passive countermeasures28may include internal air bag control, seatbelt control, knee bolster control, head restraint control, load limiting pedal control, load limiting steering control, pretensioner control, external air bag control, pedestrian protection control, and other passive countermeasures known in the art. The passive countermeasures28may also include position control of a steering wheel, seat assembly, seat back, seat cushion, head restraint, and other related components.

The active countermeasures30may include brake control, throttle control, steering control, suspension control, transmission control, and other vehicle control systems. The restraint control module24may signal the vehicle operator via the indicator of an impending potential collision so that the vehicle operator may actively perform a precautionary action, such as applying the brakes or steering to prevent a collision.

The restraint control module24may perform various sensing system and countermeasure operations in response to the object detection signals and occupant classification signals. The restraint control module24may enable various passive countermeasures and active countermeasures in response to the object detection signals. The restraint control module24as part of a countermeasure may generate a warning signal and communicate the warning signal to vehicle occupants via the indicator.

The restraint control module24may be microprocessor based such as a computer having a central processing unit, memory (RAM and/or ROM), and associated input and output buses. The restraint control module24may be an application-specific integrated circuit or be formed of other logic devices known in the art. The restraint control module24may be a portion of a central vehicle main control unit, an interactive vehicle dynamics module, a main safety controller, or may be a stand-alone controller as shown.

The restraint control module24may perform various different sensing system operations including adaptive cruise control, lane-keeping control, lane-departure control, window clearing control, collision avoidance control, countermeasure control, or other sensing system operations known in the art. The operations may be performed sequentially or simultaneously.

The restraint control module24determines which of the sensing system operations to perform. The restraint control module24while performing one or more of the sensing system operations may determine whether to perform one or more of the countermeasures20and indicate to the vehicle operator various object and vehicle status information. Depending upon relative positions, velocities, and accelerations of the detected objects, the restraint control module may also determine whether to indicate to the vehicle operator of a potential collision or may perform a countermeasure, as needed, so as to prevent a collision, mitigate a potential injury, or prevent the vehicle12from traveling outside a current lane of travel.

The indicator26is used to signal or indicate a safety system signal, which may include a calibration signal, an occupant classification sensor related signal, a warning signal, a collision-warning signal, a countermeasure signal, or an object identification signal in response to the object detection signals. The indicator26may include a video system, an audio system, an LED, a light, a global positioning system, a heads-up display, a headlight, a taillight, a display system, a telematic system, or other indicator known in the art. The indicator26may supply warning signals, collision-related information, lane departure and lane-keeping information, external-warning signals to objects or pedestrians located outside of the vehicle12, or other pre and post collision information. The warning signals may be radio frequency based or based on some other technique known in the art.

Referring now toFIG. 2, a block diagrammatic and schematic view of the smart airbag system22, which is in the form of a restraint control circuit, incorporating the smart airbag14in accordance with an embodiment of the present invention is shown. The smart airbag system22includes an airbag module internal state circuit40having the restraint control module24and the smart airbag14. The restraint control module24continuously monitors the state of the smart airbag14, indicates when a fault exists via the indicator26, and prevents deployment of or further expansion of the smart airbag14when appropriate.

The smart airbag14includes airbag state sensors42and an airbag state monitor44. The state sensors42determine the current state of the inflatable bag46and in response thereto the airbag state monitor44alters the monitored state of the smart airbag14as detected by the restraint control module24.

The airbag state monitor44alters monitored state of the inflatable bag46via a fault switch48, which is coupled to multiple state devices50. The state devices50include igniters or trigger devices52and a fault trigger substitute54. The trigger devices52are coupled to the restraint control module24and to inflators56for deployment of an inflatable bag46. The trigger devices52are used as state devices. The trigger devices52include a first trigger device58that is coupled to a first stage inflator60and a second trigger device62, which is coupled to a second stage inflator64. The second trigger device62is coupled in parallel with the fault trigger substitute54. The state devices50have a characteristic, such as resistance, that is monitored by the restraint control module. The trigger devices52, in the example embodiment shown, have a first corresponding resistance value, which is monitored by the restraints control module24. The fault trigger substitute54has a different resistance than the second trigger device62. This difference in resistance can be detected by the restraint control module24and from which the restraint control module24can determine that a fault exists with the smart airbag14. The airbag state monitor44selects either the second trigger device62or the fault trigger substitute54depending upon the state of the inflatable bag46.

The airbag sensors42generate airbag state signals in response to the expansion of the inflatable bag14and may indicate other airbag characteristics known in the art. The airbag sensors42may be of various types and styles known in the art. As an example, the airbag sensors42may include airbag internal pressure sensors (not shown) for monitoring the internal pressure of the inflatable bag46. As another example, the airbag sensors42may include a barcode type reader (not shown) for monitoring the payout of a tether (not shown), a ticker tape, or the like attached to the inflatable bag46, the amount of payout of the tether indicating the expansion of the inflatable bag46.

The airbag state monitor44is located within the smart airbag14and is separate from the restraints control module24. The airbag state monitor44, like the restraints control module24, may be microprocessor based such as a computer having a central processing unit, memory (RAM and/or ROM), and associated input and output buses. The airbag state monitor44may be an application-specific integrated circuit or be formed of other logic devices known in the art.

The state devices50may be in the form of resistors. In one embodiment of the present invention, each of the first trigger device58and the second trigger device62have a resistance of approximately 2 Ohms, whereas the fault trigger substitute54has a resistance value that is less than or greater than 2 Ohms. The resistance value of the fault trigger substitute54is such that the restraints control module24can detect that the fault trigger substitute54is selected and not the second trigger device62.

The inflators56and the inflatable bag46may be of various types and styles known in the art. The inflators56are used to inflate the inflatable bag46at different rates, to different expanded volumes, and at different forces, depending upon the occupant characteristics. The inflators56may be used sequentially, synchronously, or simultaneously.

Although the airbag state monitor44is shown as being coupled to and monitoring the second trigger device62, the airbag state monitor44may be similarly coupled to the first trigger device58. Also, although two stages are shown, any number of airbag stages may be utilized. The smart airbag14may be easily modified to accommodate for additional stages and the internal monitoring of each additional stage.

The smart airbag also includes an air bypass70that is coupled to the inflatable bag46. The air bypass70allows the restraints control module24and/or the airbag state monitor44to release air within or prevent air from entering the inflatable bag46when further inflation of the inflatable bag46is undesired or deflation is desired.

Referring now toFIG. 3, a logic flow diagram illustrating a method of indicating a state of an airbag in accordance with an embodiment of the present invention is shown.

In step100, the collision detection sensors16generate multiple object detection signals corresponding to the detection of objects within areas external to the vehicle12. In step102, the occupant classification sensors18generate occupant classification signals that include occupant characteristic related information.

In step104, the restraint control module24may determine occupant characteristics, such as size, weight, height, occupant position, and seat position, as well as whether a seat belt is utilized or whether a child safety seat is located in front or within range of an airbag. The occupant characteristics are determined in response to the occupant classification signals.

In step106, the restraint control module24monitors the state of the smart airbag14. Although associated with a particular step the restraint control module24continuously monitors that state of the smart airbag14. In one embodiment, the restraints control module24monitors the resistance of the state devices50that are coupled to the restraints control module24.

In step108, the airbag state sensors42generate airbag state signals. The airbag state signals include state related information as described above.

In step110, the airbag state monitor44determines whether a fault exists within the smart airbag14in response to the airbag state signals. When the resistance of the state devices50changes or becomes different than associated predetermined values the restraint control module24determines that a fault exists with the smart airbag14. For example, when the restraint control module24measures the resistance of the second state device62and the resistance is less than or greater than approximately 2 Ohms a fault is indicated via the indicator26. A fault may include a static physical fault, which may be mechanical or electrical, such as a short to ground within a connector or wire. A fault may also include a dynamic physical fault, such as the inflatable bag46colliding with a child safety seat or other object, before the inflatable bag46is fully inflated.

In step112, when a fault does exist the airbag state monitor44alters the indicative state of the smart airbag14to the restraint control module24by selecting or switching the coupling of the restraint control module14from the second trigger device62to the fault trigger substitute54. In step114, the restraints control module24detects the coupling and the resistance of the fault trigger substitute54, generates an airbag fault signal, and indicates the fault via the indicator26. In step116, the restraint control module24and/or the airbag state monitor44prevent the deployment of or further expansion of the inflatable bag46. When a fault is detected, during the deployment of the inflatable bag46, the restraints control module24and/or the airbag state monitor44activate the air bypass70to allow air within the inflatable bag46to escape or be released therefrom.

In step118, when a fault does not exist the airbag state monitor44maintains the selection of the second trigger device62.

In step120, the restraint control module24generates multiple safety system signals in response to the object detection signals and the occupant classification signals. The safety system signals may include countermeasures related signals and other sensing system control signals.

In step122, the restraints control module24may perform multiple sensing system operations in response to the safety system signals. As an example, the occupant classification sensors16may detect an occupant that is small in size or a child safety seat within a seat system and decelerate or prevent the activation of an inflatable bag46near the occupant or safety seat.

The above-described steps are meant to be illustrative examples; the steps may be performed sequentially, synchronously, simultaneously, or in a different order depending upon the application.

The present invention provides a smart airbag that may be used in replacement of traditional style airbags without need for the altering of a restraint control circuit. The smart airbag is capable of altering monitored state of the airbag with respect to a restraint control module such that the restraint control module can then determine that a fault exists and perform appropriate tasks as a result.