Design And Realization Of A Pedestrian Navigation Device With MEMS Inertial Sensors

With the rapid development of mobile equipment technology, many kinds of mobile equipmentbecome indispensable parts of daily life. As a new generation of satellites navigation and positioningsystem developed by American army, GPS has been commonly used in the Personal Navigation System(PNS). With the well satellites signal, GPS has omnidirectional and real-time functions for location, andcan provide high accuracy service for personal navigation. However, when in thick forest or urban areaswith tall buildings or indoor environments, GPS receiver can not normally receive satellites signal, andsatellite positioning accuracy is degraded. To overcome this shortcoming of GPS and achieve the aim ofcontinuity and dependability for personal navigation, many kinds of sensors, such as inertia sensors,ultrasonic sensors, and infrared sensors etc, have been used in the navigation system.The purpose of this paper is to explore a pedestrian navigation device made up of directionallocalizer, pedometer device and hand LCD device. Using miniature, inexpensive MEMS inertia sensorsit is possible to create self-contained systems using sensor-only navigation techniques optimized forpedestrian motion.The directional localizer attached to the wais applies MEMS IMU and magneto-resistive sensors tomeasure the direction, and realize dead-reckoning combining with the information provided bypedometer device. The pedometer device fixed on the shoe measures the foot’ acceleration, estimate stepcounting and stride length, and allows the precise identification of separate stride segments consociatedof the stance phase and the swing phase. In the stance phase, zero velocity update (ZUPT) and zeroangular rate update (ZARU) are introduced to reduce the errors of the PNS system. A Kalman Filter forclosed loop integration between the MEMS IMU measurements, the pedometer device is derived. Thefilter propagates and estimates the errors which are fed back to the DR system for correction of theinternal navigation states improving the accuracy of pedestrian navigation system. The hand LCDdevice displays navigation data and communicates with directional localizer device by CAN bus.The directional localizer also includes SD card circuit, audio input/output circuit, keyboard circuitetc. The SD card is used to store the navigation data which the user used to make the trajectory recur onthe computer; the audio input/output circuit is used to improve the efficiency of operation and increasethe man-machine interfaces of the pedestrian navigation; the keyboard is used to control the pedometerdevice and play the audio.Proof of concept tests were performed in the laboratory, stride length estimation and heading withrespect to a high accuracy reference trajectory, the performance metrics accuracy of step detection andprecision of pedestrian location.