Blast Direction Detection Using an OBA Sensor

A method of determining the source direction of a blast wave was developed by utilizing a wearable 3D air blast sensor—the OmniBlast® Air. The uniqueness of the OmniBlast® Air is that only one wearable sensor is used to determine the source direction of a blast. The OmniBlast® Air sensor has five pressure-sensing elements that are located in mutually perpendicular planes. All sensing elements are housed in a single casing with a volume of less than 2 cubic inches. The wearable blast wave sensor was tested in different orientations with respect to the blast source.

The OmniBlast® Air (OBA) sensor, shown in Figure 1, was used for the blast direction study. The defined sensing element positions and orientations are shown in Figure 1, where the geometric center of the OBA is defined as [0,0,0]. The defined positive x, y, and z axes, and defined positive azimuth, α, and elevation, ε, angles are shown in Figure 2. An experimental setup was developed that allows rotation of the OBA about the z-axis in precise increments to change the sensor’s azimuth angle with respect to the fixed blast source position. To verify the methodology, tests at five azimuth angles of 0°, 30°, 45°, 60°, and 90° were performed.

Figure 1. OBA Sensor

Figure 2. The defined positive sensor coordinates and translational and rotational axes for an OBA sensor.

The temporal indices distinctly change as the sensor is rotated, enabling the determination of the blast source direction. With this development, the wearable OmniBlast® Air will provide the capability to estimate an equivalent incident pressure with accurate blast direction detection. Stay tuned for more updates as we continue to innovate and push the boundaries of what is possible in the realm of blast safety.