Negative-stiffness vibration isolation
A new kind of vibration isolator, which is base on negative-stiffness theory, is made out for nano manufacture. In this paper, vibration isolation theory is mentioned to further explain negative-stiffness, and then Euler Columns and another negative-stiffness structure are introduced. Furthermore, the stiffness expression is figured out. Finally, a negative-stiffness vibration isolator is made to prove the theory and experiments also shows that its nature frequency is 0.45Hz and can isolate 79% of vibration at 1.9Hz and 97% at 4.9 Hz.
Design, Modeling, and Control of a Constant-Force Microgripper
This chapter proposes the design, modeling, and control of a compliant gripper with a passive-type constant-force mechanism. The constant force output is enabled by combining a positive-stiffness mechanism and a negative-stiffness mechanism. The negative stiffness is produced by a bistable fixed-guided beam with buckling behavior. The developed constant-force gripper allows the generation of constant force via its mechanical structure, which allows the elimination of force control. Analytical modeling and nonlinear finite element analysis (FEA) simulation study are carried out to evaluate the gripper performance. A prototype is developed for experimental study. To achieve a precise positioning of the gripper jaw, a discrete-time sliding mode control strategy is developed on the basis of a nonswitching-type reaching law. The effectiveness of the gripper system is validated by performing experimental studies on grasp-hold-release manipulation of micro-object.
Analysis of a coaxial-to-waveguide adaptor including a discended probe and a tuning post
A field matching analysis of a coaxial-to-waveguide adaptor incorporating a disc-ended probe and a tuning post is presented. In this analysis, the tuning post is considered as a short-circuited second probe. A computer algorithm for calculating the input impedance of this structure is developed. This algorithm is used to investigate and improve the operation of a commercially available coaxial-to-waveguide adaptor. >