FIELD

The invention relates to a crash sensor system that removes polarity (impact direction) dependence from calculations based on acceleration signals from front and side crash satellite sensors without any loss of crash discrimination performance.

BACKGROUND

The use of acceleration-based satellite sensors such as accelerometers to detect vehicle crashes is a common practice. Accelerometers are typically located at various points in the vehicle to provide the necessary information to an algorithm for making judgments about the predicted severity of on-going crash events.

Incorrect sensor polarity has been the topic for many safety related vehicle recalls over the years and continues to be a complex and difficult issue despite many best practices being put in place. Today's passive safety algorithms rely on inputs from the acceleration-based satellite sensors that are mounted in the vehicle's frontal crush zone. The front crash satellite sensors have a sensing axis and must be mounted such that the sensing axis is parallel to the crash direction that is being measured. The satellite sensors measure acceleration which inherently has a direction (i.e., polarity). Positive signals are experienced when an impact comes from one direction and negative signals are experienced when the impact comes from the opposite direction.

If the front satellite sensors are not properly configured or are mounted backwards and are providing incorrect signals to the front algorithm during a front crash, then the front algorithm will not perform as intended. This can lead to non-deployments, or late deployments in cases where an airbag deployment is desired.

If the side satellite sensors are not properly configured or are mounted backwards and are providing incorrect signals to the side algorithm during a side crash, then the side algorithm will not perform as intended. This can lead to restraint activations on the wrong side of the car. For example, a crash to the left side may result in the right side restraints being activated instead of the left side.

Thus, there is a need to provide a crash sensor system that removes polarity dependence from calculations based on acceleration signals from front and side crash satellite sensors without any loss of crash discrimination performance.

SUMMARY

An object of the invention is to fulfill the need referred to above. In accordance with the principles of the present invention, this objective is achieved by providing a crash sensor system for a vehicle, with the vehicle having a front, a rear, a left side and a right side. The system includes an electronic control unit (ECU) constructed and arranged to be disposed on the vehicle generally along a longitudinal axis of the vehicle. The ECU has a first accelerometer constructed and arranged to measure longitudinal acceleration of the vehicle during a crash event; a second accelerometer constructed and arranged to measure lateral acceleration of the vehicle during a crash event; and a processor circuit. At least a pair of front crash satellite sensors are electrically connected to the ECU and are constructed and arranged to be mounted at the front of the vehicle to detect a front or a rear crash event. Each of the front crash satellite sensors has a polarity defining a sensing direction. At least a pair of side crash satellite sensors are electrically connected to the ECU with one of the side crash satellite sensors being constructed and arranged to be mounted at the right side of the vehicle and the other side crash satellite sensor of the pair being constructed and arranged to be mounted to the left side of the vehicle to detect a side crash event. When a front or rear crash event occurs, the first accelerometer of the ECU is constructed and arranged to determine if the crash occurred at the front or at the rear of the vehicle, regardless of the polarity of the front crash satellite sensors. When a side crash event occurs, the processor circuit is constructed and arranged to determine a struck side of the vehicle independent of the second accelerometer of the ECU by summing an absolute value of all of the left side crash satellite sensors and comparing the sum to a summation of an absolute value from all of the right side crash satellite sensors, with the side with the largest summation being the struck side.

In accordance with another aspect of the invention, a method detects crash events of a vehicle, with the vehicle having a front, rear, left side and right side. The method mounts an electronic control unit (ECU) generally along a longitudinal axis of the vehicle. The ECU includes a first accelerometer constructed and arranged to measure longitudinal acceleration of the vehicle during a crash event; a second accelerometer constructed and arranged to measure lateral acceleration of the vehicle during a crash event; and a processor circuit. The method mounts at least a pair of front crash satellite sensors to the front of the vehicle to detect a front or a rear crash event, with each of the front crash satellite sensors being electrically connected to the ECU and having polarity defining a sensing direction. The method mounts at least a pair of side crash satellite sensors to the vehicle such that one of the side crash satellite sensors is mounted at the right side of the vehicle and the other side crash satellite sensor of the pair is mounted to the left side of the vehicle to detect a side crash event. Each side crash satellite sensor is connected to the ECU. When a front or rear crash event occurs, the method determines, by the first accelerometer of the ECU, whether the crash occurred at the front or at the rear of the vehicle, regardless of the polarity of the front crash satellite sensors.

Other objects, features and characteristics of the present invention, as well as the methods of operation and the functions of the related elements of the structure, the combination of parts and economics of manufacture will become more apparent upon consideration of the following detailed description and appended claims with reference to the accompanying drawings, all of which form a part of this specification.

