For the purpose of positioning in various scenes, including indoors, on open road, and side street buildings, a low-cost personal navigation unit is put forward. The unit consists of a low-cost MEMS (micro-electro-mechanical system) accelerometer, a gyroscope, a magnetometer and a GPS (global positioning system) chip, and it is capable of switching modes between indoor and outdoor situations seamlessly. The outdoor mode is MIMU (MEMS-inertial measurement unit) /GPS/magnetometer integrated mode and the indoor mode is MIMU/magnetometer integrated mode. The outdoor algorithm uses the extended Kalman filter to fuse data and provide optimum parameters. The indoor algorithm is dead reckoning, which uses vertical and forward accelerations to judge steps and uses a magnetometer to define heading. The two-axis acceleration data is used to calculate the adaptive threshold and estimate the confidence value of the steps, and when the confidence of both two axes data meet the conditions, the steps can be detected in the adaptive time windows. The detection precision is more than 95％. An experiment was conducted in complex situations. The experiment participant wearing the unit walked about 1 600 m in the experiment. The results show that the positioning error is less than 0.2％ of the total route distance.%为了能够在室内、空旷的道路上和高楼林立的城市街道上定位定向,提出一种适用于室内外无缝导航的低成本个人导航仪.该导航仪由低成本的微机械加速度计、陀螺仪、磁传感器和GPS芯片组成,具有室内外无缝导航功能,在室外采用MIMU/GPS/磁传感器组合工作模式,用扩展卡尔曼滤波技术融合各种数据,给出最优导航参数;在室内采用MIMU/磁传感器组合工作模式,采用航位推算技术,用垂向加速度计和前向加速度计数据检测步伐并使用磁传感器判断航向.使用垂向和前向加速度计数据来计算动态阈值和估计步伐可信度,然后在两向加速度计数据可信度同时满足条件的动态时间窗内检测步伐,计步精度可达95％以上.在室外内不同场景下进行了无缝导航试验,结果表明,携带个人导航仪行走1 600 m,其定位误差小于行程的0.2％.
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