Data_Sheet_1_Robust and reusable self-organized locomotion of legged robots under adaptive physical and neural communications.pdf

IntroductionAnimals such as cattle can achieve versatile and elegant behaviors through automatic sensorimotor coordination. Their self-organized movements convey an impression of adaptability, robustness, and motor memory. However, the adaptive mechanisms underlying such natural abilities of these animals have not been completely realized in artificial legged systems.MethodsHence, we propose adaptive neural control that can mimic these abilities through adaptive physical and neural communications. The control algorithm consists of distributed local central pattern generator (CPG)-based neural circuits for generating basic leg movements, an adaptive sensory feedback mechanism for generating self-organized phase relationships among the local CPG circuits, and an adaptive neural coupling mechanism for transferring and storing the formed phase relationships (a gait pattern) into the neural structure. The adaptive neural control was evaluated in experiments using a quadruped robot.ResultsThe adaptive neural control enabled the robot to 1) rapidly and automatically form its gait (i.e., self-organized locomotion) within a few seconds, 2) memorize the gait for later recovery, and 3) robustly walk, even when a sensory feedback malfunction occurs. It also enabled maneuverability, with the robot being able to change its walking speed and direction. Moreover, implementing adaptive physical and neural communications provided an opportunity for understanding the mechanism of motor memory formation.DiscussionOverall, this study demonstrates that the integration of the two forms of communications through adaptive neural control is a powerful way to achieve robust and reusable self-organized locomotion in legged robots.</p

Centrifugation-Assisted Fog-Collecting Abilities of Metal-Foam Structures with Different Surface Wettabilities

The collection of water from fog is a simple and sustainable means of obtaining freshwater for human and animal consumption. Herein, we address the use of metal foam in fog collection and present a novel fog-collecting device fabricated from copper foam. This device, which can also be used in other liquid–gas separation applications, is a 3D extension of biologically inspired 1D and 2D materials. The network structure of the 3D material effectively increased the contact area and interaction time of the skeleton structure and fog compared to those of traditional 2D fog-collecting materials. The main aspects investigated in this study were the influences of the inertial centrifugal force generated by rotating the metal-foam samples and the use of samples with different surface wettabilities on the fog-collecting performance. Superhydrophilic and superhydrophobic samples were found to have higher collection efficiencies at low and high rotational speeds, respectively, and a maximum efficiency of 86% was achieved for superhydrophobic copper foam (20 pores per inch) rotated at 1500 rpm

Presentation_1_Grade-control outdoor turning flight of robo-pigeon with quantitative stimulus parameters.pdf

IntroductionThe robo-pigeon using homing pigeons as a motion carrier has great potential in search and rescue operations due to its superior weight-bearing capacity and sustained flight capabilities. However, before deploying such robo-pigeons, it is necessary to establish a safe, stable, and long-term effective neuro-electrical stimulation interface and quantify the motion responses to various stimuli.MethodsIn this study, we investigated the effects of stimulation variables such as stimulation frequency (SF), stimulation duration (SD), and inter-stimulus interval (ISI) on the turning flight control of robo-pigeons outdoors, and evaluated the efficiency and accuracy of turning flight behavior accordingly.ResultsThe results showed that the turning angle can be significantly controlled by appropriately increasing SF and SD. Increasing ISI can significantly control the turning radius of robotic pigeons. The success rate of turning flight control decreases significantly when the stimulation parameters exceed SF > 100 Hz or SD > 5 s. Thus, the robo-pigeon's turning angle from 15 to 55° and turning radius from 25 to 135 m could be controlled in a graded manner by selecting varying stimulus variables.DiscussionThese findings can be used to optimize the stimulation strategy of robo-pigeons to achieve precise control of their turning flight behavior outdoors. The results also suggest that robo-pigeons have potential for use in search and rescue operations where precise control of flight behavior is required.</p

Supplementary Material from Inversion of friction anisotropy in a bio-inspired asymmetrically structured surface

Friction anisotropy is an important property of many surfaces that usually facilitate the generation of motion in a preferred direction. Such surfaces are very common in biological systems and have been the templates for various bio-inspired materials with similar tribological properties. So far friction anisotropy is considered to be the result of an asymmetric arrangement of surface nano- and microstructures. However, here we show by using bio-inspired sawtooth-structured surfaces that the anisotropic friction properties are not only controlled by an asymmetric surface topography, but also by the ratio of the sample–substrate stiffness, the aspect ratio of surface structures, and by the substrate roughness. Systematically modifying these parameters, we were able to demonstrate a broad range of friction anisotropies, and for specific sample–substrate combinations even an inversion of the anisotropy. This result highlights the complex interrelation between the different material and topographical parameters on friction properties and sheds new light on the conventional design paradigm of tribological systems. Finally, this result is also of great importance for understanding functional principles of biological materials and surfaces, as such inversion of friction anisotropy may correlate with gait pattern and walking behaviour in climbing animals, which in turn may be used in robotic applications

Endlein_etal_2016_data

Data for figures 2-4

S_Tab_1-4 from The use of clamping grips and friction pads by tree frogs for climbing curved surfaces

Table 1: Mass, snout-vent length (SVL) and fore limb span for the six Chinese gliding frogs (Rhacophorus dennysi); Table 2–4: Statistical result

S_Video_1 from The use of clamping grips and friction pads by tree frogs for climbing curved surfaces

Ground reaction forces of a downwards climbing tree frog (Rhacophorus dennysi). 24 3D force transducers (white ‘tiles’ of approx. 30x30mm) were arranged around the front half of an octagon, in order to measure the clamping forces between opposite feet. The in-plane forces (Fx and Fy) are shown in blue, the normal forces (Fz) in red. Compressive normal forces are indicated as downward pointing arrows whereas adhesive normal forces as upward pointing arrows. Note that a normal force component also occurs when a frog pulled at a transducer in an oblique way (for explanation see inset of Fig.1. The frog's mass was 156