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| VIT Personal Navigation System (VITPN) is a low size, low weight and ultra-low power consumption system capable of solving personal navigation and urban positioning task. The system continuously and uninterruptedly outputs the coourdinates of the user necessary to determine the full set of navigation data and attitude parameters as well as motion parameters.
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| VITPN: Personal Navigator |
Currently none of navigation equipment vendors offers a “personal navigation tool”, a portable navigating device, operating in all conditions. At the same time, authoritative market research shows a growing demand for portable fully autonomous positioning system for pedestrians. Such systems are indispensable for emergency services, when uninterrupted position determination is critical. Such a task cannot be achieved by GPS alone, because indoor, in forest area, in the mines satellite signal is weak or not available at all.
 About
| V.I.T.-Engineering has developed the prototype of the personal navigation system (VITPN) based on the low-size inertial/GPS integrated system. VITPN software uses sophisticated originally designed inertial navigation and GPS integration algorithm based on new approach to the problem of pedestrian navigation solution. VITPN is a fully autonomous system intended for determination of absolute or relative 3D coordinates (in horizontal plane and elevation). The system continuously and uninterruptedly outputs the coordinates of a user, which then can be transmitted over the selected communication channel. |
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VITPN architecture
The personal navigation system prototype includes the following hardware:
- The inertial measuring unit (the block of autonomous sensors), which includes the three-axial blocks of accelerometers, gyroscopes, and magnetometers, and a tiny bar altimeter.
- GPS receiver, built on a technology of high sensitivity satellite signals processing (SiRF).
- The device for data recording, displaying and combined data processing (the handheld computer like notebook).
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The attitude position of the unit relative to the human body is arbitrary, but it shall not change in time of walking, i.e. the unit is rigid on a strap or in the pocket.
VITPN architecture
The VITPN software algorithm block-diagram consists of three main blocks: classic strap-down algorithm, distance computation and block of correction. The first block implements the classic strap-down INS algorithm, this algorithm implements the local-level navigation frame, it provides with the attitude information of the mounted inertial measurement unit. The known altitude of the block allows computing the projections of the vector of Earth magnetic field to the axes of the navigation frame, and, hence, determining the magnetic heading.
The second block implements the alternative distance computation technique. This block fulfills step-detecting function and the step length is calculated. The third block is step length correction block. If GPS data is available, it is possible to calibrate the step length calculation procedure. For this purpose the traveled distances, calculated by measurement unit indications and by GPS indications, are compared, and coefficient is calibrated. |
The block-diagram of the algorithm |
The third block also implements the heading correction procedure. While GPS data is available, it is possible to calibrate long-term gyroscopic drift, using the heading information, obtained from GPS. In this case the influence of the magnetic disturbances, caused by the operational environment, is minimized, and, hence, do not lead to the errors in positioning determination. After the two preliminary calibration procedures are done, the positions are calculated. In order to minimize the positioning error, caused by integrating of the northern and eastern increments of position, the final correction procedure is used. If GPS data is available, the GPS coordinate indications can be used for correction of the coordinates, provided by the navigation system.
Indoor and outdoor test results
Autonomous urban positioning |
Stairs motion |
| The VITPN prototype indoor and outdoor tests showed that system demonstrates the good autonomous accuracy. The hardware-software combination implemented in VITPN takes the advantage of the complete strapdown INS architecture to provide the right attitude compensation. However, the external magnetic disturbance provided by building construction may cause the significant position error. Such an error may be reduced by means of more advanced magnetic compass installation or different positioning technique implementation (map matching, for instance). |
Autonomous indoor navigation |
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