A mechanism based on a four-linkage mechanism and a hybrid-drive six-linkage mechanism is designed to imitate the function of the basilisk lizard running on water. The kinematics analysis of the water running mechanism is carried out by using the linkage mechanism kinematics and the D-H method. Then the stability analysis of the mechanism is carried out according to the critical conditions. At last the mechanism is simulated and optimized for getting the maximum momentum in the slap phase and the maximum force in the stroke phase. And the simulation result shows that the mechanism can satisfy the requirement of biped water running.

Null frequencies in the spectrum of a phase difference signal are used for intrusion localization since their values are associated with the position of intrusion in a Sagnac interferometer. However, searching the null frequencies individually is troublesome and unreliable for localization. In this paper, an algorithm which directly captures the interval of null frequencies is proposed to achieve a simpler and more robust intrusion localization. By applying the modified spectrum to a second fast Fourier transform, the interval responds as multiple peaks in the resulting location curve. After determining the values of the base peak and its harmonic peaks, the intrusion's distance can be localized. Intrusions are applied at a position of 130 km in a sensing fiber. Due to the resolution increase as peak order, localization performance of 2nd harmonic peak is 25 m, which is 34% better than the base peaks. By calculating the average of the localization results by all remarkable peaks, localization performance improves by 47% in laboratory experiments and by 24% in practical applications over the previous single-peak localization algorithm.

In the Sagnac fiber optic interferometer system, the phase difference signal can be illustrated as a convolution of the waveform of the invasion with its occurring-position-associated transfer function h(t); deconvolution is introduced to improve the spatial resolution of the localization. In general, to get a 26 m spatial resolution at a sampling rate of 4×10⁶ s^-1, the algorithm should mainly go through three steps after the preprocessing operations. First, the decimated phase difference signal is transformed from the time domain into the real cepstrum domain, where a probable region of invasion distance can be ascertained. Second, a narrower region of invasion distance is acquired by coarsely assuming and sweeping a transfer function h(t) within the probable region and examining where the restored invasion waveform x(t) gets its minimum standard deviation. Third, fine sweeping the narrow region point by point with the same criteria is used to get the final localization. Also, the original waveform of invasion can be restored for the first time as a by-product, which provides more accurate and pure characteristics for further processing, such as subsequent pattern recognition.

A mechanism based on a Grashof crank-link mechanism and a hybrid-drive six-linkage mechanism is designed to fit its ankle and sole trajectories and imitate the function of the basilisk lizard running on water. The linkage mechanism kinematics theory and the geometric identity condition are used to analyze the mechanism kinematics, and an instance simulation is carried out to prove that the mechanism can satisfy the kinematics requirements of water-running.

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