A data efficient method for characterization of chameleon tongue motion using Doppler radar - PubMed (original) (raw)

A data efficient method for characterization of chameleon tongue motion using Doppler radar

Aditya Singh et al. Annu Int Conf IEEE Eng Med Biol Soc. 2012.

Abstract

A new technique is described for study of the study of high velocity animal movements using a continuous wave Doppler radar operating at 24 GHz. The movement studied was tongue projection kinematics during prey capture by the lizard Chamaeleo Jacksonii. The measurements were verified with a high speed video reference, recorded at 1000 frames per second. The limitations and advantages of both the methodologies are compared and tongue speeds of 3:65 m/s were observed. These results show a useful application of radar to augment visual sensing of biological motion and enable the use of monitoring in a wider range of situations.

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Figures

Fig. 1

Fig. 1

Chameleon poised to strike a cricket clipped in place above the radar (with a flat-head alligator clip). Note the ruler below the perch for length reference.

Fig. 2

Fig. 2

Sketch of test setup seen from above. The cricket is located just above the radar antennas and the perch (wooden branch) is situated to locate the chameleon's head at the level of the radar antennas. The camera is about 1 m away from the radar antenna and perch.

Fig. 3

Fig. 3

Plots of tongue speed for the second experiment as determined from (a) radar and (b) video data. The tongue motion appears as a short spike of motion in the radar data and not like the step seen in the video data because the radar monitored the chameleon for a much longer time than the high speed video camera. Even at this higher sample rate and longer duration of observation the data from the radar system is much more manageable. The reported maximum speed for both the radar and video measurements (with equivalent sample times) showed excellent agreement at 3.64 m/s and 3.65 m/s, respectively.

Fig. 4

Fig. 4

Radar output of chameleon striking bait with indications of automatically determined strike time(s). This information can be used to quickly focus attention on times for analysis and saving video. Though the data was analyzed after the experiment, the strike indication could be generated in real time using a similar algorithm.

Fig. 5

Fig. 5

Radar baseband output signals I and Q plotted for 300 ms (top) and 100 ms (bottom) showing the speed difference between tongue protrusion and tongue projection during the strike.

Fig. 6

Fig. 6

Chameleon shortly after striking cricket, in the process of drawing its tongue (and the now attached cricket) back to its mouth. Visible in this still frame are parts of its tongue moving in different ways: what little motion the base has is generally vertical (waving it up and down) while the thinner middle portion is behaving more like a cable or rope and the thicker part at the end with the cricket is swinging back like a weight. Unlike the earlier tongue projection, this set of motions do not appear independently in the radar output and measuring this interplay during tongue retraction would be very difficult if not impossible with a single radar system.

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References

    1. Wainwright P, Kraklau D, Bennett A. Kinematics of tongue projection in Chamaeleo oustaleti. Journal of experimental biology. 1991;159(1):109.
    1. Flanders M. Visually guided head movement in the African chameleon. Vision Research. 1985;25(7):935–942. [Online]. Available: http://www.sciencedirect.com/science/article/pii/0042698985902044. - PubMed
    1. Lin J. Noninvasive microwave measurement of respiration. Proceedings of the IEEE. 1975;63(10):1530–1530.
    1. Nanzer J, Anderson M, Josserand T, et al. Detection of moving intruders from a moving platform using a Ka-band continuous-wave doppler radar. Antennas and Propagation Society International Symposium, 2009 APSURSI '09 IEEE. 2009 Jun;:1–4.
    1. Park BK, Boric-Lubecke O, Lubecke VM. Arctangent demodulation with dc offset compensation in quadrature Doppler radar receiver systems. Microwave Theory and Techniques, IEEE Transactions on. 2007 May;55(5):1073–1079. - PubMed

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