scholarly journals Shape-induced obstacle attraction and repulsion during dynamic locomotion

2021 ◽  
pp. 027836492198937
Author(s):  
Yuanfeng Han ◽  
Ratan Othayoth ◽  
Yulong Wang ◽  
Chun-Cheng Hsu ◽  
Rafael de la Tijera Obert ◽  
...  
Keyword(s):  
Body Shape ◽  
Passive Control ◽  
Energy Landscape ◽  
Open Loop ◽  
Physical Interaction ◽  
Robot Locomotion ◽  
3D Terrain ◽  
Potential Energy Landscape ◽  
Body Shapes ◽  
Obstacle Geometry

Robots still struggle to dynamically traverse complex 3D terrain with many large obstacles, an ability required for many critical applications. Body–obstacle interaction is often inevitable and induces perturbation and uncertainty in motion that challenges closed-form dynamic modeling. Here, inspired by recent discovery of a terradynamic streamlined shape, we studied how two body shapes interacting with obstacles affect turning and pitching motions of an open-loop multi-legged robot and cockroaches during dynamic locomotion. With a common cuboidal body, the robot was attracted towards obstacles, resulting in pitching up and flipping-over. By contrast, with an elliptical body, the robot was repelled by obstacles and readily traversed. The animal displayed qualitatively similar turning and pitching motions induced by these two body shapes. However, unlike the cuboidal robot, the cuboidal animal was capable of escaping obstacle attraction and subsequent high pitching and flipping over, which inspired us to develop an empirical pitch-and-turn strategy for cuboidal robots. Considering the similarity of our self-propelled body–obstacle interaction with part–feeder interaction in robotic part manipulation, we developed a quasi-static potential energy landscape model to explain the dependence of dynamic locomotion on body shape. Our experimental and modeling results also demonstrated that obstacle attraction or repulsion is an inherent property of locomotor body shape and insensitive to obstacle geometry and size. Our study expands the concept and usefulness of terradynamic shapes for passive control of robot locomotion to traverse large obstacles using physical interaction. Our study is also a step in establishing an energy landscape approach to locomotor transitions.

scholarly journals An energy landscape approach to locomotor transitions in complex 3D terrain

2020 ◽  
Vol 117 (26) ◽  
pp. 14987-14995 ◽  
Author(s):  
Ratan Othayoth ◽  
George Thoms ◽  
Chen Li
Keyword(s):  
Potential Energy ◽  
Complex Terrain ◽  
Statistical Physics ◽  
Energy Landscape ◽  
Three Dimensional ◽  
Single Mode ◽  
Physical Interaction ◽  
Landscape Approach ◽  
3D Terrain ◽  
Potential Energy Landscape

Effective locomotion in nature happens by transitioning across multiple modes (e.g., walk, run, climb). Despite this, far more mechanistic understanding of terrestrial locomotion has been on how to generate and stabilize around near–steady-state movement in a single mode. We still know little about how locomotor transitions emerge from physical interaction with complex terrain. Consequently, robots largely rely on geometric maps to avoid obstacles, not traverse them. Recent studies revealed that locomotor transitions in complex three-dimensional (3D) terrain occur probabilistically via multiple pathways. Here, we show that an energy landscape approach elucidates the underlying physical principles. We discovered that locomotor transitions of animals and robots self-propelled through complex 3D terrain correspond to barrier-crossing transitions on a potential energy landscape. Locomotor modes are attracted to landscape basins separated by potential energy barriers. Kinetic energy fluctuation from oscillatory self-propulsion helps the system stochastically escape from one basin and reach another to make transitions. Escape is more likely toward lower barrier direction. These principles are surprisingly similar to those of near-equilibrium, microscopic systems. Analogous to free-energy landscapes for multipathway protein folding transitions, our energy landscape approach from first principles is the beginning of a statistical physics theory of multipathway locomotor transitions in complex terrain. This will not only help understand how the organization of animal behavior emerges from multiscale interactions between their neural and mechanical systems and the physical environment, but also guide robot design, control, and planning over the large, intractable locomotor-terrain parameter space to generate robust locomotor transitions through the real world.

scholarly journals Locomotor transitions in the potential energy landscape-dominated regime

2021 ◽  
Vol 288 (1949) ◽  
Author(s):  
Ratan Othayoth ◽  
Qihan Xuan ◽  
Yaqing Wang ◽  
Chen Li
Keyword(s):  
Potential Energy ◽  
Energy Landscape ◽  
Three Dimensional ◽  
Single Mode ◽  
Model Systems ◽  
Physical Interaction ◽  
Potential Energy Landscape ◽  
Potential Energy Landscapes ◽  
General Physical ◽  
Physical Principles

To traverse complex three-dimensional terrain with large obstacles, animals and robots must transition across different modes. However, the most mechanistic understanding of terrestrial locomotion concerns how to generate and stabilize near-steady-state, single-mode locomotion (e.g. walk, run). We know little about how to use physical interaction to make robust locomotor transitions. Here, we review our progress towards filling this gap by discovering terradynamic principles of multi-legged locomotor transitions, using simplified model systems representing distinct challenges in complex three-dimensional terrain. Remarkably, general physical principles emerge across diverse model systems, by modelling locomotor–terrain interaction using a potential energy landscape approach. The animal and robots' stereotyped locomotor modes are constrained by physical interaction. Locomotor transitions are stochastic, destabilizing, barrier-crossing transitions on the landscape. They can be induced by feed-forward self-propulsion and are facilitated by feedback-controlled active adjustment. General physical principles and strategies from our systematic studies already advanced robot performance in simple model systems. Efforts remain to better understand the intelligence aspect of locomotor transitions and how to compose larger-scale potential energy landscapes of complex three-dimensional terrains from simple landscapes of abstracted challenges. This will elucidate how the neuromechanical control system mediates physical interaction to generate multi-pathway locomotor transitions and lead to advancements in biology, physics, robotics and dynamical systems theory.

scholarly journals Propelling and perturbing appendages together facilitate strenuous ground self-righting

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Ratan Othayoth ◽  
Chen Li
Keyword(s):  
Kinetic Energy ◽  
Potential Energy ◽  
Energy Landscape ◽  
The Body ◽  
Body Motion ◽  
Physical Interaction ◽  
Landscape Model ◽  
High Pitch ◽  
Potential Energy Landscape ◽  
Do So

Terrestrial animals must self-right when overturned on the ground, but this locomotor task is strenuous. To do so, the discoid cockroach often pushes its wings against the ground to begin a somersault which rarely succeeds. As it repeatedly attempts this, the animal probabilistically rolls to the side to self-right. During winged self-righting, the animal flails its legs vigorously. Here, we studied whether wing opening and leg flailing together facilitate strenuous ground self-righting. Adding mass to increase hind leg flailing kinetic energy increased the animal’s self-righting probability. We then developed a robot with similar strenuous self-righting behavior and used it as a physical model for systematic experiments. The robot’s self-righting probability increased with wing opening and leg flailing amplitudes. A potential energy landscape model revealed that, although wing opening did not generate sufficient kinetic energy to overcome the high pitch potential energy barrier to somersault, it reduced the barrier for rolling, facilitating the small kinetic energy from leg flailing to probabilistically overcome it to self-right. The model also revealed that the stereotyped body motion during self-righting emerged from physical interaction of the body and appendages with the ground. Our work demonstrated the usefulness of potential energy landscape for modeling self-righting transitions.

scholarly journals The intimate relationship between structural relaxation and the energy landscape of monatomic liquid metals

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Franz Demmel ◽  
Louis Hennet ◽  
Noel Jakse
Keyword(s):  
High Temperature ◽  
Velocity Field ◽  
Liquid State ◽  
Liquid Metals ◽  
Energy Landscape ◽  
Experimental Studies ◽  
Transport Parameter ◽  
Arrhenius Behavior ◽  
Liquid Aluminium ◽  
Potential Energy Landscape

AbstractThe characteristic property of a liquid, discriminating it from a solid, is its fluidity, which can be expressed by a velocity field. The reaction of the velocity field on forces is enshrined in the transport parameter viscosity. In contrast, a solid reacts to forces elastically through a displacement field, the particles are trapped in their potential minimum. The flow in a liquid needs enough thermal energy to overcome the changing potential barriers, which is supported through a continuous rearrangement of surrounding particles. Cooling a liquid will decrease the fluidity of a particle and the mobility of the neighbouring particles, resulting in an increase of the viscosity until the system comes to an arrest. This process with a concomitant slowing down of collective particle rearrangements might already start deep inside the liquid state. The idea of the potential energy landscape provides an attractive picture for these dramatic changes. However, despite the appealing idea there is a scarcity of quantitative assessments, in particular, when it comes to experimental studies. Here we present results on a monatomic liquid metal through a combination of ab initio molecular dynamics, neutron spectroscopy and inelastic x-ray scattering. We investigated the collective dynamics of liquid aluminium to reveal the changes in dynamics when the high temperature liquid is cooled towards solidification. The results demonstrate the main signatures of the energy landscape picture, a reduction in the internal atomic structural energy, a transition to a stretched relaxation process and a deviation from the high-temperature Arrhenius behavior of the relaxation time. All changes occur in the same temperature range at about $$1.4 \cdot T_{melting}$$ 1.4 · T melting , which can be regarded as the temperature when the liquid aluminium enters the landscape influenced phase and enters a more viscous liquid state towards solidification. The similarity in dynamics with other monatomic liquid metals suggests a universal dynamic crossover above the melting point.

scholarly journals SmartFit: Smartphone Application for Garment Fit Detection

Electronics ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 97
Author(s):  
Kamrul H. Foysal ◽  
Hyo Jung Chang ◽  
Francine Bruess ◽  
Jo Woon Chong
Keyword(s):  
Body Shape ◽  
Online Shopping ◽  
Smartphone Application ◽  
Shape Detection ◽  
Time Saving ◽  
Apparel Shopping ◽  
Promising Solution ◽  
Clothing Fit ◽  
Body Shapes ◽  
Garment Fit

The apparel e-commerce industry is growing day by day. In recent times, consumers are particularly interested in an easy and time-saving way of online apparel shopping. In addition, the COVID-19 pandemic has generated more need for an effective and convenient online shopping solution for consumers. However, online shopping, particularly online apparel shopping, has several challenges for consumers. These issues include sizing, fit, return, and cost concerns. Especially, the fit issue is one of the cardinal factors causing hesitance and drawback in online apparel purchases. The conventional method of clothing fit detection based on body shapes relies upon manual body measurements. Since no convenient and easy-to-use method has been proposed for body shape detection, we propose an interactive smartphone application, “SmartFit”, that will provide the optimal fitting clothing recommendation to the consumer by detecting their body shape. This optimal recommendation is provided by using image processing and machine learning that are solely dependent on smartphone images. Our preliminary assessment of the developed model shows an accuracy of 87.50% for body shape detection, producing a promising solution to the fit detection problem persisting in the digital apparel market.

scholarly journals Enhancing ductility in bulk metallic glasses by straining during cooling

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Rodrigo Miguel Ojeda Mota ◽  
Ethen Thomas Lund ◽  
Sungwoo Sohn ◽  
David John Browne ◽  
Douglas Clayton Hofmann ◽  
...  
Keyword(s):  
Metallic Glasses ◽  
Energy Landscape ◽  
Bulk Metallic Glasses ◽  
Bulk Glass ◽  
Liquid Cooling ◽  
Fictive Temperature ◽  
Cooling Method ◽  
Potential Energy Landscape ◽  
Major Shortcoming ◽  
Processing Techniques

AbstractMost of the known bulk metallic glasses lack sufficient ductility or toughness when fabricated under conditions resulting in bulk glass formation. To address this major shortcoming, processing techniques to improve ductility that mechanically affect the glass have been developed, however it remains unclear for which metallic glass formers they work and by how much. Instead of manipulating the glass state, we show here that an applied strain rate can excite the liquid, and simultaneous cooling results in freezing of the excited liquid into a glass with a higher fictive temperature. Microscopically, straining causes the structure to dilate, hence “pulls” the structure energetically up the potential energy landscape. Upon further cooling, the resulting excited liquid freezes into an excited glass that exhibits enhanced ductility. We use Zr44Ti11Cu10Ni10Be25 as an example alloy to pull bulk metallic glasses through this excited liquid cooling method, which can lead to tripling of the bending ductility.

scholarly journals Effects Of Combinations Of Patternmaking Methods And Dress Forms On Garment Appearance

2017 ◽  
Vol 17 (3) ◽  
pp. 277-286 ◽  
Author(s):  
Chinami Fujii ◽  
Masayuki Takatera ◽  
KyoungOk Kim
Keyword(s):  
Sensory Evaluation ◽  
Body Shape ◽  
Front Side ◽  
Calculation Methods ◽  
Ideal Body ◽  
Sensory Evaluations ◽  
Body Shapes ◽  
Made In ◽  
The Ideal

AbstractWe investigated the effects of the combinations of patternmaking methods and dress forms on the appearance of a garment. Six upper garments were made using three patternmaking methods used in France, Italy, and Japan, and two dress forms made in Japan and France. The patterns and the appearances of the garments were compared using geometrical measurements. Sensory evaluations of the differences in garment appearance and fit on each dress form were also carried out. In the patterns, the positions of bust and waist darts were different. The waist dart length, bust dart length, and positions of the bust top were different depending on the patternmaking method, even when the same dress form was used. This was a result of differences in the measurements used and the calculation methods employed for other dimensions. This was because the ideal body shape was different for each patternmaking method. Even for garments produced for the same dress form, the appearances of the shoulder, bust, and waist from the front, side, and back views were different depending on the patternmaking method. As a result of the sensory evaluation, it was also found that the bust and waist shapes of the garments were different depending on the combination of patternmaking method and dress form. Therefore, to obtain a garment with better appearance, it is necessary to understand the effects of the combinations of patternmaking methods and body shapes.

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