Bioinspired 3D-Printed Snakeskins Enable Effective Serpentine Locomotion of a Soft Robotic Snake.

We present a multi-material three-dimensional-printed snakeskin with orthotropic friction anisotropy, which permits undulatory slithering of a soft snake robot on rough surfaces. Such a snakeskin is composed of a soft skin base and embedded rigid scales attached to the robot's ventral surface. The bioinspired designs of scale shapes and arrangements lead effectively to various types of anisotropic friction, and provide means of switching robot's locomotion direction to be either the same as or opposite to the propagation direction of the traveling-wave undulation. Furthermore, steering of locomotion can be achieved by applying additional pressure bias in one air path to break symmetry of body deformation. We also successfully demonstrate the snake robot's mobility on various outdoor rough substrates, including concrete surfaces and a grass lawn, as well as pipes of different dimensions and materials, for potential field applications.

A Novel Well Drill Assisted with High-Frequency Vibration Using the Bending Mode.

It is important for companies to increase the efficiency of drilling as well as prolong the lifetime of the drilling tool. Since some previous investigations indicated that a superposition of well drilling with an additional vibration increases the drilling efficiency, this paper introduces a novel well drill which is assisted with additional vibrations by means of piezoelectric sandwich bending vibration transducer. The proposed drill uses bending vibrations in two different directions to from an elliptical trajectory movement, which can help the drill to break the surface of hard material more efficiently and clean away the lithic fragments more easily. The proposed well drill with bending vibration transducer is designed to have a resonance frequency of the first bending vibration mode of about 1779 Hz. The motion equation of the particle on the edge of the drill bit is developed and analyzed. The vibration trajectory of the particle on the edge of the drill bit is calculated by using finite element method. A prototype of the proposed drill using bending vibrations is fabricated and tested to verify the aim of drilling efficiency increase. The feed speed of the vibration assisted drilling is tested to be about 0.296 mm/s when the excitation voltage of the transducer is 300 V, while this speed decreases to about 0.195 mm/s when no vibration is added. This comparison shows that the feed speed of the vibration assisted drilling is about 52% higher than that of the normal drilling, which means the proposed drill has a better efficiency and it is important to consider vibration superimposition in well drilling. In addition, the surface of the drill hole gained by the vibration assisted drilling is smoother than that of the normal drilling, which makes the clearance easier.

Fast auto-focusing search algorithm for a high-speed and high-resolution camera based on the image histogram feature function.

In this paper, we developed an auto-focus image quality evaluation function from the histogram feature function (HFF) of a high-speed camera. Based on this function, we then proposed a fast auto-focus search algorithm. We further demonstrated that the auto-focus image quality evaluation function we proposed requires fewer computational resources, while providing a more effective focusing area and more moderate sensitivity, compared to the traditional evaluation function. In contrast to the traditional climbing method, our proposed fast auto-focusing search algorithm also can spot the focus point in a shorter time, effectively reducing the round trips of the focusing motor and improving the focusing accuracy.