A smart micro-cantilever in a creative gas sensor with high sensitivity is presented. The resonance frequency shifting of
the cantilever is monitored to detect its mass change caused by adsorption of certain gas molecules. The cantilever has a
more compact MEMS structure and the smart functions because of the sensor with a self-actuating and detecting (SAD)
vibration system, which is integration of a vibration actuating system and a detecting system. The model of the smart
beam is analyzed by computer simulation. Design rules of the beam are obtained according to related discuss with
function goal of extremely rare gas detection. After fabrication and test of the smart cantilever, an improved solution of
the smart cantilever is introduced by comparison study of the computer simulation and experiment results of the
Relative state estimation is a key technology in the spacecraft formation flying area. Since there exists nonlinear perturbation and uncertainties in the dynamic model, it is necessary to use a robust filter to estimate the relative state. A robust Kalman filter is presented in this paper for discrete time-varying systems with uncertain nonlinear perturbation and uncertainties in the state, output and input matrices, and this filter is applied to solve the relative state estimation problem of spacecraft-formation maintenance. Simulation results show the high performance of the filter.
Resonating cantilever-based microbiochemical sensors usually consist of a vibration actuating system and a vibration detecting system, which complicates the sensor design and fabrication. We present a new idea for testing the cantilever's vibration without an exclusive detector. The amplitude of vibration can be detected by measuring the third harmonic of the actuating current, and the cantilever's resonance frequency can be consequently obtained. The change of the resonance frequency provides information about the biochemical reaction, which alters the mass of the cantilever and its natural frequency. A system model based on the idea is established and an approximate solution is given. The relation between the vibration state and the third harmonic is discussed, and a corresponding simulation is performed. The system sensitivity is evaluated. Both theoretical and simulation results show that the amplitude of the third harmonic of the actuating current can be used as a criterion to determine the cantilever's vibration state. The idea promises a simpler mechanical structure, thus a cheaper sensor. Sensors based on this idea would also be robust to atrocious environments because the material of the cantilever can be chosen from a wide range.