News from R&D: Pedestrian Dead Reckoning

Florian Freitag, 

As our team is growing and becoming more and more experienced we introduce a “column” to share insights from our experts. So, today’s contribution comes from R&D, sharing some insights on Pedestrian Dead Reckoning (PDR) for improved indoor positioning and as a pre-stage for SLAM.

PDR is the determination of the relative position of a walking user, by considering smartphone sensor data. PDR is a staged process in which we determine step length and walking direction, once the accelerometer of a smartphone detects a walking movement. The actual position can then be determined by adding this relative position to a known absolute reference position which has to be determined by other ways, e.g. Wi-Fi or Bluetooth Triangulation.

All that’s needed for PDR is an average smartphone which is equipped with the sensors accelerometer and magnetometer. Gyroscopes are not required but desirable for increased accuracy since the heading angle can be corrected for changes in phone orientation. For example, the holding direction of the smartphone is usually somewhat different to the walking direction.



So, what is all this maths good for? In a nutshell, PDR makes for more accurate, stable, and smoother indoor positioning. Between absolute positions determined by radio signals, the position is estimated using a smartphone’s in-built sensors. Thus, realtive positioning reduces the jumping of a displayed position on the map.