Using OrthoSLAM and Aiding Techniques for Precise Pedestrian Indoor Navigation

An Integrated Pedestrian Navigation System (IPNS) for precise indoor localization is presented in this paper. A laser scanner enables mapping and long-term stability of the navigation solution. Reliable information about personnel positions and escape routes is a crucial factor in many security or first responder missions. Especially in indoor scenarios in previously unknown environments, precise localization within the explored surroundings is essential for effective coordination. Therefore, a robust and accurate indoor IPNS with mapping capabilities enables fast and successful missions and reduces risk for the deployed personnel. However, the mentioned applications make high demands on navigational hard-and software. Tracking highly dynamic motions is required as well as providing a long-term accurate navigation estimation, even without reliable satellite navigation signals. The pedestrian navigation system has to be portable, light and small, which leads to limited computational power being available. Deployment in unknown environments requires use of exteroceptive sensors and mapping techniques. Our proposal is an Integrated Pedestrian Navigation System comprising two inertial measurements units (IMUs), mounted at the foot and the torso, a magnetometer and a barometer, aided by a two-dimensional laser scanner. The navigation solution is obtained by a Strapdown approach, with Zero Velocity Updates used as aiding technique. The laser scanner enables mapping of the surrounding structure and guarantees long-term accuracy of the position and attitude estimation. The scan data is processed using an Orthogonal Simultaneous Localization and Mapping (OrthoSLAM) technique. In this approach, a reduction of required computational power is reached by considering only straight and perpendicular structures. OrthoSLAM exploits the fact that man-made buildings consist of orthogonal structures to a large extent and provides long-term stable navigation aiding at low computational cost. Therefore, this method is targeted to the special conditions of indoor navigation. First results indicate that the combined Dual-IMU/magnetometer/laser system can meet the challenging requirements of pedestrian indoor navigation. The capabilities of our approach will be demonstrated using post-processed data obtained in real-world test scenarios.