Pose tracking of magnetic objects

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1 Pose tracking of magnetic objects Niklas Wahlström Department of Information Technology, Uppsala University, Sweden February 2, 2018 VASCO workshop

2 Magnetometer measurement models 1. Common use: Magnetometer provides orientation information. Assume that the magnetometer (almost) only measures the local (earth) magnetic field. 1 / 17 niklas.wahlstrom@it.uu.se VASCO workshop

3 Magnetometer measurement models 1. Common use: Magnetometer provides orientation information. Assume that the magnetometer (almost) only measures the local (earth) magnetic field. 2. My use: Magnetometer(s) to provide position and orientation information. 1 / 17 niklas.wahlstrom@it.uu.se VASCO workshop

4 Magnetometer measurement models 1. Common use: Magnetometer provides orientation information. Assume that the magnetometer (almost) only measures the local (earth) magnetic field. 2. My use: Magnetometer(s) to provide position and orientation information. Magnetic mapping: Build a map of the (indoor) magnetic field. 1 / 17 niklas.wahlstrom@it.uu.se VASCO workshop

5 Magnetic mapping Build a map of the indoor magnetic field. This map can be used for localization. We have used Bayesian models (Gaussian processes) to model such fields with good results 2 / 17 niklas.wahlstrom@it.uu.se VASCO workshop

6 Magnetometer measurement models 1. Common use: Magnetometer provides orientation information. Assume that the magnetometer (almost) only measures the local (earth) magnetic field. 2. My use: Magnetometer(s) to provide position and orientation information. Magnetic mapping: Build a map of the (indoor) magnetic field. Magnetic tracking: Measure the position and orientation of a known magnetic source. 3 / 17 niklas.wahlstrom@it.uu.se VASCO workshop

7 Sensor setup We use a sensor network with four three-axis magnetometers to determine the position and orientation of a magnet. 4 / 17 niklas.wahlstrom@it.uu.se VASCO workshop

8 Magnetic tracking Advantages Cheap sensors 5 / 17 niklas.wahlstrom@it.uu.se VASCO workshop

9 Magnetic tracking Advantages Cheap sensors Small sensors 5 / 17 niklas.wahlstrom@it.uu.se VASCO workshop

10 Magnetic tracking Advantages Cheap sensors Small sensors Low energy consumption 5 / 17 niklas.wahlstrom@it.uu.se VASCO workshop

11 Magnetic tracking Advantages Cheap sensors Small sensors Low energy consumption No weather dependency 5 / 17 niklas.wahlstrom@it.uu.se VASCO workshop

12 Magnetic tracking Advantages Cheap sensors Small sensors Low energy consumption No weather dependency Passive unit, requires no batteries 5 / 17 niklas.wahlstrom@it.uu.se VASCO workshop

13 Mathematical model - dipole field The magnetic field can be described with a dipole field. B(r) r m J(r ) B(r) = µ ( ) 0 4π r 5 3r r T r 2 I 3 m }{{} =C(r) m 1 2 r J(r )d 3 r 6 / 17 niklas.wahlstrom@it.uu.se VASCO workshop

14 Sensor model - single dipole The measurements can be described with a state-space model x k+1 = F k x k + G k w k, w k N (0, Q), y k,j = h j (x k ) + e k, e k N (0, R) Point target sensor model (one dipole) h j (x k ) = C(r k θ j )m k, x k = [r T k v T k m T k ω T k ]T C(r) = µ 0 4π r 5 (3rrT r 2 I 3 ), Measurement from a sensor network of magnetometers positioned at {θ j } J j=1. Degrees of freedom 3D position 2D orientation 7 / 17 niklas.wahlstrom@it.uu.se VASCO workshop

15 z-coordinate [m] z-coordinate [m] Experiment 1 Trajectory 0.3 Trajectory y-coordinate [m] x-coordinate [m] y-coordinate [m] accuracy is 8 / 17 niklas.wahlstrom@it.uu.se VASCO workshop

16 Experiment 2 - setup 9 / 17 niklas.wahlstrom@it.uu.se VASCO workshop

17 Experiment 2 - results - position Position [m] Time [s] Black: Ground truth position. Color: Estimated position 10 / 17 niklas.wahlstrom@it.uu.se VASCO workshop

18 Experiment - results - orientation 100 Orientation [degree] Time [s] Black: Ground truth orientation. Color: Estimated orientation 11 / 17 niklas.wahlstrom@it.uu.se VASCO workshop

19 Application 1: 3D painting book 12 / 17 niklas.wahlstrom@it.uu.se VASCO workshop

20 Application 2: Digital water colors 13 / 17 niklas.wahlstrom@it.uu.se VASCO workshop

21 Application 3: Digital table hockey 14 / 17 niklas.wahlstrom@it.uu.se VASCO workshop

22 Application 4: Digital pathology 15 / 17 niklas.wahlstrom@it.uu.se VASCO workshop

23 Stylaero AB In February 2017 a company was started around this technology In total seven people are involved in the company on part-time. Collaborations with both gaming companies and industrial partners. 16 / 17 niklas.wahlstrom@it.uu.se VASCO workshop

24 Thank you! 17 / 17 niklas.wahlstrom@it.uu.se VASCO workshop

Pose tracking of magnetic objects

Pose tracking of magnetic objects Niklas Wahlström Department of Information Technology, Uppsala University, Sweden Novmber 13, 2017 niklas.wahlstrom@it.uu.se Seminar Vi2 Short about me 2005-2010: Applied