Real-time Wireless Sensing with Spatiotemporal Tracking

This study proposes the use of an innovative array of accelerometers for inertial tracking that is enabled through the use of a non-Cartesian hyper-coordinate frame. Traditional inertial tracking technologies employ an array of accelerometers and gyroscopes oriented in the orthogonal axes of the Cartesian coordinate system. The gyroscope sensors are responsible for deducing the relative orientation of the instrumented object, while the accelerometer measurements are double integrated to approximate the change in linear position relative to the local coordinate frame. Since the position determination is dependent on the orientation derivation, the accuracy and stability of the gyroscope sensors to a large extent determines the overall system performance. Consequently, high-performance gyroscopes are generally used in inertial tracking systems, thereby driving the system cost significantly higher. The proposed approach exclusively utilizes accelerometers in an innovative six axis orientation that, through linear algebra, resolves linear and angular accelerations. The functional layout is processed in the context of hyperdimensional coordinates which ultimately produce an inherent vector redundancy when resolved in the Cartesian coordinate frame. This revised architecture is anticipated to alleviate many of the issues plaguing traditional inertial tracking that stem from the stability of derived orientation from gyroscope readings. In addition, the exclusion of gyroscopes from the design significantly reduces the unit cost of the system. This paper additionally presents the development of a wireless system that incorporates the above described, unique array of dedicated sensors for inertial tracking to provide accurate determination of position and orientation of the sensor over time. The system permits access for additional channels of sensors for application specific monitoring tasks. This allows sensing on objects in motion and in regions or flow patterns that cannot be easily instrumented with traditional wired systems while maintaining knowledge of instantaneous position relative to the initial location. To date, the majority of wireless sensor network deployments have enabled instrumentation of widespread sites, such as civil structures, to alleviate the expense associated with the lengths of cable necessary to connect the sensors to a central acquisition station. The alternative approach sought utilizes the unrestrained nature of the wireless sensor to extend the use of this technology beyond static monitoring into applications in which the sensor node travels across an area without a priori knowledge of the sensor motion. Documentation of the hardware development of the proposed wireless sensing node as well as assessment of the system performance will be provided.