Analysis of Reaction Force and Locomotor Behavior on Geckos in Time- and Frequency-domain during Climbing on Vertical Substrates

Since the commencement of climbing robots, the moving ability of climbing robots has continuously lagged far behind that of climbing animal. A primary cause is the insufficient understanding of how animals govern their climbing locomotion. To reveal the mechanism of vertical locomotion and enhance the performance of climbing robots, we have measured the reaction forces acting on climbing geckos and recorded the locomotor behaviors synchronously. The coordinates of reference points were regressed to analyze kinematic feature factors. Meanwhile, the data of reaction forces were further processed by fast Fourier transform and wavelet transform to acquire time-frequency domain characteristics. The results show a good agreement between the reaction forces and the locomotor behaviors in time-frequency domain; the main locomotor frequency of trunk in fore-aft direction is twice that in lateral direction; the excellent adhesion system of geckos enables them to climbing up vertical substrate with not only a very tiny impact in time scale but also not easily identifiable characteristics in frequency-domain. Above research will help deepen our understanding of the climbing locomotion, and provide a more precise prototype for the design of gecko-like robot.