Background
Heterotopic Ossification (HO) is a common condition referring to ectopic bone formation in soft tissues. It has two major etiologies, acquired (more common) and genetic. The acquired form is closely related to tissue trauma. The exact pathogenesis of this disease remains unclear; however, there is ongoing research in prophylactic and therapeutic treatments that is promising.
Conclusions
Due to HO potential to cause disability, it is so important to differentiate it from other causes in order to establish the best possible management.
In the last decade, the Land-Vehicle Navigation (LVN) market has grown rapidly. For most LVN systems, GPS is used for positioning. However, GPS has poor accuracy in urban areas due to signal blockages. Therefore, the LVN market has targeted the integration of other sensors with GPS. In this case, sensors' cost and size are major issues. Recent advances in MEMS inertial sensors made it possible to develop low-cost and compact IMUs. However, MEMS provide poor accuracy when used without updates (e.g., during GPS outages). In such periods, other updates are required for better performance. Vehicle full-stops, i.e., Zero-Velocity-Updates (ZUPTs), are usually applied for this purpose. However, this is not practical especially when GPS blockages are frequent. In this paper, 3D Auxiliary Velocity Updates (AVUs) are used, namely, non-holonomic constraints and odometer-derived velocity. Using kinematic MEMS/GPS data with several GPS signal blockages, the results showed a significant accuracy improvement after applying AVUs.
The integration of the Global Positioning System (DGPS) with an Inertial Navigation System (INS) has been implemented for several years. In an integrated INS/DGPS system, the DGPS provides positions while the INS provides attitudes. In case of DGPS outages (signal blockages), the INS is used for positioning until the DGPS signals are available again. One of the major issues that limit the INS accuracy, as a stand-alone navigation system, is the level of sensor noise. The problem with inertial data is that the required signal is buried into a large window of high frequency noise. If such noise component could be removed, the overall inertial navigation accuracy is expected to improve considerably. The INS sensor outputs contain actual vehicle motion and sensor noise. Therefore, the resulting position errors are proportional to the existing sensor noise and vehicle vibrations. In this paper, wavelet techniques are applied for de-noising the inertial measurements to minimize the undesirable effects of sensor noise and other disturbances. To test the efficiency of inertial data de-noising, two road vehicle INS/DGPS data sets are utilized. Compared to the obtained position errors using the original inertial measurements, the results showed that the positioning performance using de-noised data improves by 34%-63%. K E Y W O R D S 1. DGPS. 2. INS. 3. Inertial Sensor Noise. 4. Wavelets. 1. I N T R O D U C T I O N. The last two decades have shown an increasing trend in using integrated INS/DGPS systems in many applications requiring position and attitude information. For example in mobile mapping systems, the INS/DGPS navigation information (position and attitude) is used to georeference an imaging sensor mounted on the same carrier of the integrated INS/DGPS system. Another application of INS/DGPS that has received the attention of geodesists in the last decade is airborne gravimetry. Using the INS/DGPS navigation solution and subtracting the aircraft acceleration (obtained by twice differentiating DGPS positions) and the total sensed acceleration (obtained by INS accelerometer specific force measurements), the gravity field can be determined with high accuracy. In general, GPS provides highly accurate position and velocity and can provide attitude information when a multi-antenna system is used. However, GPS is not suitable enough for many mapping and navigation applications that require continuous navigation information (Schwarz and Wei, 1995). Cycle slips caused by loss of lock between the receiver and a satellite are one of the limitations of GPS. In addition, some
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