scholarly journals Co-opting propelling and perturbing appendages facilitates strenuous ground self-righting

2021 ◽  
Author(s):  
Ratan Othayoth ◽  
Qihan Xuan ◽  
Chen Li
Keyword(s):  
Kinetic Energy ◽  
Potential Energy ◽  
Energy Barrier ◽  
Energy Landscape ◽  
Landscape Model ◽  
High Pitch ◽  
Energy Fluctuation ◽  
Potential Energy Barrier ◽  
Potential Energy Landscape ◽  
Do So

AbstractTerrestrial animals must self-right when overturned on the ground. To do so, the discoid cockroach often pushes its wings against the ground to begin a somersault but rarely succeeds in completing it. As it repeatedly attempts this, it probabilistically rolls to the side to self-right. Here, we studied whether seemingly wasteful leg flailing in this process helps. Adding mass to increase hind leg flailing kinetic energy fluctuation 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. As legs flailed more vigorously and wings opened more, self-righting became more probable. A potential energy landscape model revealed that, although wing opening did not generate sufficient kinetic energy to overcome the high pitch potential energy barrier, it reduced barriers for rolling, facilitating the small kinetic energy fluctuation from leg flailing to probabilistically overcome roll barriers to self-right.Impact statementWhen overturned terrestrial animals self-right on the ground, their seemingly wasteful yet ubiquitous flailing of appendages is crucial in providing kinetic energy fluctuation to probabilistically overcome potential energy barriers.

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.

Field Emission Basics: The Water Bucket Analogy

1995 ◽  
Vol 3 (10) ◽  
pp. 20-21
Author(s):  
Doug Rathkey
Keyword(s):  
Kinetic Energy ◽  
Energy Level ◽  
Potential Energy ◽  
Electric Field ◽  
Cathode Material ◽  
Fermi Level ◽  
Field Emission ◽  
Energy Barrier ◽  
Thermionic Emission ◽  
Potential Energy Barrier

In the water bucket analogy (Figure 1), the water level in a bucket represents the Fermi level - the highest occupied energy level in the cathode material. The work function is the energy required to get the “water droplets” (electrons) from the top of the liquid out of the bucket and ever the side (i.e., the distance equivalent to the potential energy barrier).In photoemission, the energy of a photon can remove an electron at the Fermi level from the cathode material and can impart enough kinetic energy of travel to allow it to escape from the bucket (Figure 1a). In thermionic emission, heat provides the energy to boil the electrons off and out of the bucket (Figure 1b). Finally, in field emission, a high electric field can thin the side of the bucket enough so that the electrons can tunnel right through it (Figure 1c). There are two types of field emission: cold field emission (CFE) and Schottky emission (SE).

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.

Hybrid-Bistable Vibration Energy Harvester With Adaptive Potential Well

2018 ◽  
Author(s):  
Jinki Kim ◽  
Patrick Dorin ◽  
K. W. Wang
Keyword(s):  
Energy Harvesting ◽  
Potential Energy ◽  
Cantilever Beam ◽  
Potential Barrier ◽  
Energy Barrier ◽  
Electrical Power ◽  
Vibration Energy ◽  
Frequency Spectra ◽  
Potential Energy Barrier ◽  
Piezoelectric Energy

Many common environmental vibration sources exhibit low and broad frequency spectra. In order to exploit such excitations, energy harvesting architectures utilizing nonlinearity, especially bistability, have been widely studied since the energetic interwell oscillations between their stable equilibria can provide enhanced power harvesting capability over a wider bandwidth compared to the linear counterpart. However, one of the limitations of these nonlinear architectures is that the interwell oscillation regime may not be activated for a low excitation level that is not strong enough to overcome the potential energy barrier, thus resulting in low amplitude intrawell response which provides poor energy harvesting performance. While the strategic integration of bistability and additional dynamic elements has shown potential to improve broadband energy harvesting performance by lowering the potential barrier, there is a clear opportunity to further improve the energy harvesting performance by extracting electrical power from the kinetic energy in the additional element that is induced when the potential barrier is lowered. To explore this opportunity and advance the state of the art, this research develops a novel hybrid bistable vibration energy harvesting system with a passive mechanism that not only adaptively lowers the potential energy barrier level to improve broadband performance but also exploits additional means to capture more usable electrical power. The proposed harvester is comprised of a cantilever beam with repulsive magnets, one attached at the free end and the other attached to a linear spring that is axially aligned with the cantilever (a spring-loaded magnet oscillator). This new approach capitalizes on the adaptive bistable potential that is passively realized by the spring-loaded magnet oscillator, which lowers the double-well potential energy barrier thereby facilitating the interwell oscillations of the cantilever across a broad range of excitation conditions, especially for low excitation amplitudes and frequencies. The interwell oscillation of the cantilever beam enhances not only the piezoelectric energy harvesting from the beam but also the electromagnetic energy harvesting from the spring-loaded magnet oscillator by inducing large amplitude vibrations of the magnet oscillator. Numerical investigations found that the proposed architecture yields significantly enhanced energy harvesting performance compared to the conventional bistable harvester with fixed magnet.

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