Novel applications for miniature IMU s

Transcription

1 Novel applications for miniature IMU s WORKSHOP GEÏNTEGREERDE NAVIGATIE vrijdag 15 december 2006, NLR Xsens Technologies B.V. Per Slycke (CTO)

2 About Xsens Based in Enschede, The Netherlands Founded in 2000 (spin off University of Twente) Xsens develops and supplies products for measurement of motion, orientation and position, based upon miniature MEMS inertial sensor technology

3 What is a miniature IMU? Miniature about 30g Embedded lower power DSP 3D orientation estimate by EKF Output quaternion, DCM or Euler Digital output RS-232/422/485 or USB 3D Acceleration (m/s 2 ) Noise density 0.1mg/ Hz 3D Angular velocity (rad/s) Noise density deg/s/ Hz 3D Earth magnetic field (nt) ω a g m

4 IMU similarity to human vestibular system gyroscopes accelerometers

5 3D Orientation estimates Gravity and North referenced Attitude and Heading reference system (AHRS) Basic assumptions Average acceleration in local Earth fixed coordinates is zero The measured magnetic field is the Earth magnetic field (distortions are temporal) Implemented in an EKF

6 3D Orientation estimates Predict x t+1 = f(x t, w t ) ˆx t t Correct y t = h(x t, v t ) ˆx t t 1

7 3D Orientation estimates Predict ˆx t t Correct ˆx t t 1

8 Typical miniature IMU specs Orientation accuracy: 0.5 roll/pitch 1 heading Resolution ~ 0.05 Accuracy depends on validity of assumptions Inertial data: Orthogonality 0.1 3D Acceleration (m/s 2 ) Noise density 0.1mg/ Hz 3D Angular velocity (rad/s) Noise density deg/s/ Hz Bias stability after temperature model ~ 1-2 deg/s 3D Earth magnetic field (nt)

9 Example product: MTi The world s smallest Attitude and Heading Reference System Output: Pitch, roll, heading Acc, gyro, magn. field Stabilization of robots, vehicles and more Link to movie Small, low-cost and highly accurate

10 Application; marine RADIAN; miniature marine Attitude and Heading Reference Systems for ROV s and AUV s SCOUT; ultra-short base length underwater acoustic positioning

11 Application; miniature UAVs Unmanned miniature helicopter payloads cameras and other sensors for use in aerial filming aerial overview (e.g. fire, border control) routine tasks (e.g. traffic inspection) Input to control system for stabilization & control in miniature helicopter

12 Application; human motion Use of several inertial 3D orientation sensors on the body Xsens Xbus system + MTx IMU, synchronized low overhead communication (Bluetooth wireless) Learning humanoid robots complex motions and behavior EPFL- LASA Calinon, S. and Billard, A. (2006) Learning of Gestures by Imitation in a Humanoid Robot. Dautenhahn, K. and Nehaniv, C.L. (eds.). Imitation and Social Learning in Robots, Humans and Animals: Behavioural, Social and Communicative Dimensions. Cambridge University Press. in press

13 Aiding of miniature IMU s extending applications Until now 3DOF orientation tracking only By using a flexible framework of sensor fusion (EKF) complementary sensory inputs can be added relatively easy Complementary sensory inputs (a.k.a. aiding) enables Accurate 6DOF tracking Accurate 3DOF tracking in environments where inertial/magnetic only is not possible even more exciting applications!

14 Aiding of miniature IMU s some examples Examples of different aiding sources GNSS (Low-cost miniature = MTi-G) Biomechanical constraints (Moven) Local positioning Optokinetic tracking systems RF tracking systems Magnetic tracking system (FreeMotion) Computer vision (MATRIS)

15 GNSS aiding of IMU: MTi-G Integrated miniature GNSS and IMU 65g (excl. antenna) GPS receiver GPS L1, 16 ch, 4 Hz DGPS, WAAS, EGNOS & MSAS Active antenna, -158 db tracking sensitivity Embedded low-power DSP with loosely coupled GNSS-baro-inertial EKF Output (digital serial): Position (LLA) and velocity (NED) (inertial aided) Pitch, roll and heading (GNSS stabilized) acc, gyro, mag.field, baro Control and navigation of (Unmanned) Aerial and Land Vehicles Small, low-cost and highly accurate

16 MTi-G navigation solution estimates Predict ˆx t t Correct ˆx t t 1

17 Example of novel applications MTi-G Head tracking in dynamic environments Artificial Horizon display in seethrough HMD (TNO) Pilot awareness using 3D audio cues (head tracking) (US AFIT) See also: US Wright Patterson Air Force Base (AFIT) Joffrion, J.M., Raquet, J.F., and Brungart, D.S. Sonic Boon: Head Tracking for 3D Audio Using a GPS-Aided MEMS IMU. Inside GNSS, 1(1), 32-41, 2006

18 Biomech aiding of IMUs: Moven 6DOF inertial human motion capturing system 16 inertial trackers 23-segment body model 100m wireless range No cameras, emitters or markers needed Motion capturing for animation (film/game), rehab and biomechanics, training & simulation Easy-to-use and low investment costs

19 Overview of Moven system µs synchronization! 16 IMU s x 120 Hz 100m wireless range

20 Moven 6DOF mocap estimates Predict ˆx t t Correct ˆx t t 1

21 Details 6DOF mocap estimates IMU Position = a(t) dt dt Joint constraint (articulate body) Limit drift a Sensor fusion small offset, noise Position v Other (e.g. markers) x t

22 Moven movies Link to Movie

23 Example application Moven Multi actor fully immersive virtual training environment e.g. 2 Moven systems + optokinetic wide area tracker or GPS Training and simulation Dismounted soldier training Special forces, firefighters, police Military training urban terrain (MOUT)

24 Local positioning aiding of IMU Very similar to GNSS aiding Completely other type of motions Much higher accuracy Between 1mm 1cm More symmetrical DOP Limited range Local infrastructure needed Examples Optokinetic: VICON, ART etc. RF: LPM, Ubisense Magnetic: FreeMotion Example: optokinetic aiding using VICON

25 Local positioning aiding of IMU Predict ˆx t t Correct ˆx t t 1

26 Optokinetic aided miniature IMU Benefits: Bridge data-gaps (e.g. few seconds) Higher update rate Smoother kinematics Less cameras or beacons needed Rauch-Tung- Striebel smoothing for offline applications Z-coordinate (m) error (cm) Vicon Spline Kalman Position estimates Missing optical data Forward Kalman Smoothed Kalman Position errors time (s)

27 Magnetic actuation aiding of IMU Use 3D magnetic field sensors in IMU Create 3D alternating magnetic field Deduce relative 3D position and orientation estimates from magnetic field transmission

28 6DOF estimates fusing IMU and magnetic arm ab/adduction actuator on pelvis sensor on upper arm + RMS errors combined inertial and magnetic: 5 mm Accepted for publication in IEEE Transactions on Biomedical Engineering PhD Thesis: Inertial and Magnetic Sensing of Human Motion, D. Roetenberg, May 2006, University of Twente

29 Computer vision aiding of IMU Track position and orientation (pose) of the camera Example application: Augmented Reality Enhance human vision: display virtual objects in real-time correctly aligned to the world seen through a moving camera Maintenance

30 6DOF estimates using computer vision aiding of IMU Predict ˆx t t Correct ˆx t t 1

31 Details computer vision warp scene model 2D/3D correspondences camera centre current image image object

32 Example video of real-time tracking with computer vision aided IMU Prototype of tightly coupled camera and IMU by Xsens Sensor Fusion for Augmented Reality, J. D. Hol, T. B. Schön, F. Gustafsson, P. J. Slycke, THE 9TH INTERNATIONAL CONFERENCE ON INFORMATION FUSION, FLORENCE (ITALY), JULY 2006.

33 Thank you! Come see us at USE Köln (GER) [08 May May 2007] AUVSI's Unmanned Systems Europe 2007 visit: Sensor+Test - Nürnberg (GER) [22 May May 2007] 14th International Trade Fair for Sensorics, Measuring and Testing Technologies visit: EWOMS Amsterdam (NL) [31 May June 2007] European Workshop On Movement Science visit: