This paper presents a novel redundantly piezo-actuated three-degree-of-freedom XYθ _z compliant mechanism for nano-positioning, driven by four mirror-symmetrically configured piezoelectric actuators (PEAs). By means of differential motion principle, linearized kinematics and physically bi-directional motions in all the three directions are achieved. Meanwhile, the decoupled delivering of three-directional independent motions at the output end is accessible, and the essential parallel and mirror symmetric configuration guarantees large output stiffness, high natural frequencies, high accuracy as well as high structural compactness of the mechanism. Accurate kinematics analysis with consideration of input coupling indicates that the proposed redundantly actuated compliant mechanism can generate three-dimensional (3D) symmetric polyhedral workspace envelope with enlarged reachable workspace, as compared with the most common parallel XYθ _z mechanism driven by three PEAs. Keeping a high consistence with both analytical and numerical models, the experimental results show the working ranges of ±6.21 μ m and ±12.41 μ m in X - and Y -directions, and that of ±873.2 μ rad in θ _z -direction with nano-positioning capability can be realized. The superior performances and easily achievable structure well facilitate practical applications of the proposed XYθ _z compliant mechanism in nano-positioning systems.

Taking the area CCD optical system as a whole, the analysis methods of the influence of vibrations on its imaging quality have been relatively mature. However, external vibrations will cause different vibrations of optical components inside the opto-mechanical structure. The existing methods are not suitable for analyzing optical components with different vibrations and TDICCD imaging. This paper studies the influence of vibrations on the imaging quality of the integrated TDICCD aerial camera. The relationship between the vibration responses of structures and the imaging quality is established by mathematical models. First, a vibration beam trajectory model of the integrated TDICCD aerial camera is established for the first time using geometric optics and ray tracing. The deviations of the optical axis caused by vibrations in the object plane can be obtained. Then, this paper establishes a TDICCD vibration modulation transfer function model based on statistical moments. The vibration MTF of pixels of each column in the complex two-dimensional moving image captured by the TDICCD can be obtained through this model. Furthermore, a simulation imaging model of the integrated TDICCD aerial camera is established. The influence of vibrations on the imaging quality can be directly obtained through images. Finally, the accuracy of the models established in this paper is verified by multiple tests. The results show that the imaging quality of the integrated TDICCD aerial camera decreases rapidly with the increase of the acceleration excitation.

The flapping wing micro air vehicle (FWMAV) has been attracting lots of interest since the 1990s and is one of the research hotspots in microminiaturization design. However, along with the miniaturization of FWMAV development, flight endurance becomes the bottleneck that significantly impedes the rapid development for these aircrafts because of the critical limit in energy supply due to the limited overall size and weight. In this paper, energy recovery technology was developed for FWMAV with the new type polyvinylidene fluoride (PVDF) piezoelectric wing which could generate the electric potential energy caused by the wing deformation due to the characteristics of the PVDF material. A single crank double rocker mechanism flapping platform was designed to test the deformation energy collection effect and aerodynamic lift. The PVDF wing surface was divided into 16 grid areas to be measured respectively. The lift, output voltage and output power variations for the different flapping frequency was successfully obtained in tests. By analyzing test data, if could be found that the output power could reflect the flutter condition without equipping other sensors and adding extra weight to the aircraft. Moreover, when the flapping frequency was accelerated to 12 Hz, the output power and root mean square (RMS) voltage could increase to 21 μW and 6 V respectively, which is enough to power micro electronic devices such as LED lights.

A multi-mode flapping wing micro air vehicle (FWMAV) that uses a figure eight wingtip motion trajectory with wing flapping, rotation, and swing motion is presented in this paper. The flapping wing vehicle achieves three active degrees of freedom (DOF) wing movements only with one driving micromotor which has a good balance in the mechanism design (that is inspired by natural fliers) and total weight. Owing to these characteristics being integrated into the simple mechanism design, the aerodynamic force is improved. The aerodynamic performance of the thrust force is improved by 64.3 % compared to one that could only flap up and down with one active DOF under the condition of routine flapping frequency.