Auckland Bioengineering Institute


Wireless inertial measurements

bioinst-mark-finch
Mark Finch holds a wireless inertial measurement unit designed at the ABI.

We have developed our own inductively-rechargeable nine-axis wireless inertial measurement unit (IMU). Our device (named WIMOTIONZ) is capable of measuring linear accelerations in three axes, angular rates about three axes, and magnetic field strength in three axes. The controlling chipset uses a wireless transceiver that streams data wirelessly to a receiver connected to a host computer. The device has wireless power transfer capabilities, allowing the battery to be recharged by placing the chip onto a ‘charge pad’. The wireless power transfer enables the chipset to be hermetically sealed, thereby waterproofing the sensor. The IMU, shown in Figure 1, is 22 mm x 34 mm x 10 mm in size and has a mass of approximately 12 g, which is, to our knowledge, the smallest wireless IMU available in the world.

How is this applied to the real world? Well, using data collected from IMU’s we can essentially recreate the motion of that particular sensor. Furthermore, if you put multiple sensors on different limb segments, and create a smart model to define and constrain the system, you can get a very accurate representation of the body’s movement. For example, if we were interested in analysing a cyclist’s lower limbs; we would develop a kinematic model of the cyclist’s lower limbs, and use the measurements obtained from our inertial sensors, which are rigidly attached to limb segments (on the thigh and shank in this case), to drive the kinematic model in real-time.

Researchers and graduate students


Mark Finch

Mark Finch
Honorary ABI member
Email: mark.finch@imeasureu.com
Phone: +64 21 2415 736

Funding partners


  • Auckland UniServices Stage Gate Grant
  • Australian Institute of Sport, Australian Government/Australian Sports Commission, 'High Performance Sport Research Fund'

Publications


  1. Finch, M.C.; Lintern, T.O.; Taberner, A.J.; Nielsen, P.M.F.; , "Effectiveness of model-based motion estimation from an inertial measurement unit," Sensing Technology (ICST), 2011 Fifth International Conference on , vol., no., pp.607-611, Nov. 28 2011-Dec. 1 2011
  2. Lintern T, Finch MC, Balaraman A, Taberner AJ, Nielsen, PMF, Nash MP. Characterising joint properties of the neck for studying shaken baby syndrome. In ISB 2011 Congress XXIII. 2011. Brussels, Belgium.
  3. Lintern T, Finch MC, Taberner AJ, Nielsen, PMF, Nash MP. Comparison of System Identification Techniques in the Analysis of a Phantom for Studying Shaken-baby Syndrome. In 33rd Annual International Conference of the IEEE-Engineering-in-Medicine-and-Biology-Society. 2011. Boston, Ma: IEEE.