In-plane prestressed hair clip mechanism for the fastest untethered compliant fish robot

A trend has emerged over the past decades pointing to the harnessing of structural instability in movable, programmable, and transformable mechanisms. Inspired by a steel hair clip, we combine the in-plane assembly with a bistable structure and build a compliant flapping mechanism using semi-rigid plastic sheets and installed it on both a tethered pneumatic soft robotic fish and an untethered motor-driven one to demonstrate its unprecedented advantages. Designing rules are proposed following the theories and verification. A two-fold increase in the swimming speed of the pneumatic fish compared to the reference is observed and the further study of the untether fish demonstrates a record-breaking velocity of 2.03 BL/s (43.6 cm/s) for the untethered compliant swimmer, outperforming the previously report fastest one with a significant margin of 194%. This work probably heralds a structural revolution for next-generation compliant robotics.

Road-network-based Rapid Geolocalization

It has always been a research hotspot to use geographic information to assist the navigation of unmanned aerial vehicles. In this paper, a road-network-based localization method is proposed. We match roads in the measurement images to the reference road vector map, and realize successful localization on areas as large as a whole city. The road network matching problem is treated as a point cloud registration problem under two-dimensional projective transformation, and solved under a hypothesise-and-test framework. To deal with the projective point cloud registration problem, a global projective invariant feature is proposed, which consists of two road intersections augmented with the information of their tangents. We call it two road intersections tuple. We deduce the closed-form solution for determining the alignment transformation from a pair of matching two road intersections tuples. In addition, we propose the necessary conditions for the tuples to match. This can reduce the candidate matching tuples, thus accelerating the search to a great extent. We test all the candidate matching tuples under a hypothesise-and-test framework to search for the best match. The experiments show that our method can localize the target area over an area of 400 within 1 second on a single cpu.