Crumpling and Unfolding of Montmorillonite Hybrid Nanocoatings as Stretchable Flame‐Retardant Skin

Abstract

Flame‐retardant coatings are widely used in a variety of personnel or product protection, and many applications would benefit from film stretchability if suitable materials are available. It is challenging to develop flame‐retardant coatings that are stretchable, eco‐friendly, and capable of being integrated on mechanically dynamic devices. Here, a concept is reported that uses pretextured montmorillonite (MMT) hybrid nanocoatings that can undergo programed unfolding to mimic the stretchability of elastomeric materials. These textured MMT coatings can be transferred onto an elastomeric substrate to achieve an MMT/elastomer bilayer device with high stretchability (225% areal strain) and effective flame retardancy. The bilayer composite is utilized as flame‐retardant skin for a soft robotic gripper, and it is demonstrated that the actuated response can manipulate and rescue irregularly shaped objects from a fire scene. Furthermore, by depositing the conformal MMT nanocoatings on nitrile gloves, the firefree gloves can endure direct flame contact without ignition. Montmorillonite–elastomer bilayer architectures with high stretchability and effective flame retardancy can be applied as flame‐retardant protective skins for soft robotic grippers and nitrile gloves. With the stretchable and flame‐retardant barriers, the soft pneumatic actuator is capable of continuous inflation/deflation within flames and can act as a compliant gripper for manipulating and rescuing irregular objects from a fire scene.

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An Efficient Gyro-Aided Optical Flow Estimation in Fast Rotations With Auto-Calibration

Abstract

Optical Flow (OF) measures the displacement of the projections of visual landmarks on the image plane and is widely used for motion and structure estimations. Fast rotational motion results in large image motion and poses a major challenge to many OF algorithms. To improve the performance of OF estimations, gyroscopes can be adopted to predict the image motion between adjacent frames when the camera motion is dominated by rotation. This paper first proposes an offline method for calibrating the camera focal length, gyroscope bias, the relative orientation and time offset between the camera and gyroscopes without using a man-made target. Then a simple and efficient method is proposed to aid the OF computation with the gyroscope readings. Our approach is evaluated using a low-cost endoscope-gyroscope system and shows improved visual tracking performance as compared to the standalone OF algorithm. The method is suited for use on lightweight platforms equipped with gyroscopes and an endoscopic camera, which potentially can provide efficient image guidance in endoscopic procedures.

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Preliminary development of a skull-mounted lightweight parallel robot toward minimally invasive neurosurgery (PDF Free Download). Available from: [accessed May 30 2018].