Power and Control Autonomy for High-Speed Locomotion With an Insect-Scale Legged Robot

2018 ◽  
Vol 3 (2) ◽  
pp. 987-993 ◽  
Author(s):  
Benjamin Goldberg ◽  
Raphael Zufferey ◽  
Neel Doshi ◽  
Elizabeth Farrell Helbling ◽  
Griffin Whittredge ◽  
...  
2020 ◽  
Author(s):  
Jeff Gau ◽  
Ryan Gemilere ◽  
James Lynch ◽  
Nick Gravish ◽  
Simon Sponberg ◽  
...  

AbstractCentimeter-scale fliers that combine wings with springy elements must contend with the high power requirements and mechanical constraints of flapping wing flight. Insects utilize elastic energy exchange to reduce the inertial costs of flapping wing flight and potentially match wingbeat frequencies to a mechanical resonance. Flying at resonance may be energetically favorable under steady conditions, but it is difficult to modulate the frequency of a resonant system. Evidence suggests that insects utilize frequency modulation over long time scales to adjust aerodynamic forces, but it remains an open question the extent to which insects can modulate frequency on the wingstroke-to-wingstroke timescale. If wingbeat frequencies deviate from resonance, the musculature must work against the elastic flight system, thereby potentially increasing energetic costs. To assess how insects address the simultaneous needs for power and control, we tested the capacity for wingstroke-to-wingstroke wingbeat frequency modulation by perturbing free hovering Manduca sexta with vortex rings while recording high-speed video at 2000 fps. Because hawkmoth flight muscles are synchronous, there is at least the potential for the nervous system to modulate frequency on each wingstroke. We observed ± 16% wingbeat frequency modulation in just a few wing strokes. Via instantaneous phase analysis of wing kinematics, we found that over 85% of perturbation responses required active changes in motor input frequency. Unlike their robotic counterparts that explicitly abdicate frequency modulation in favor of energy efficiency, we find that wingstroke-to-wingstroke frequency modulation is an underappreciated control strategies that complements other strategies for maneuverability and stability in insect flight.


1968 ◽  
Vol 170 (1021) ◽  
pp. 435-456 ◽  

This paper reports a behavioural analysis of the movements and righting responses of the abdominal pleopods (swimmerets) and uropods (tail fans) of the lobster Homarus americanus . The movements of individual swimmerets, studied from high-speed motion pictures, consist of a basic power stroke–return stroke cycle, upon which other cyclic power and control movements are superimposed. Tilting a lobster around the long axis of its body initiates bilaterally asymmetrical swimmeret beating. The swimmerets on the side tilted upward beat out toward the side, while those on the side tilted downward beat either straight to the rear, or not at all. These bilaterally asymmetrical swimmeret movements produce a cyclic righting torque around the long axis of the lobster’s body. The peak-to-peak amplitude of this torque is directly proportional to the frequency of swimmeret beating. The characteristics of the righting torque were related to the movements of individual swimmerets. Tilting a lobster around its long axis also evokes bilaterally asymmetrical uropod movements. The uropod on the side tilted downward is spread open, while the uropod on the side tilted upward is closed. It is argued that these movements also contribute to the production of righting torque. The righting responses of both the swimmerets and the uropods are controlled exclusively by the statocyst receptors. The position and acceleration receptors of the statocysts probably both participate in the control of the responses. Destroying one statocyst shifts the position of symmetry for the swimmerets and uropods from upright to 20° toward the injured side. Either the right or left statocyst can alone control the righting responses of the uropod and swimmerets of either side, however, even though the afferent responses of the two statocysts to roll in one direction are opposite. Neural models based on the bilaterally reciprocal organization of statocyst influences are proposed to explain these findings.


2005 ◽  
pp. 29-30
Author(s):  
Naveen Sharma ◽  
William Stanley

Author(s):  
Phillip Drew

The years since the beginning of the twenty-first century have seen a significant incursion of international human rights law into the domain that had previously been the within the exclusive purview of international humanitarian law. The expansion of extraterritorial jurisdiction, particularly by the European Court of Human Rights, means that for many states, the exercise of physical power and control over an individual outside their territory may engage the jurisdiction of human rights obligations. Understanding the expansive tendencies of certain human rights tribunals, and the apparent disdain they have for any ambiguity respecting human rights, it is offered that the uncertain nature of the law surrounding humanitarian relief during blockades could leave blockading forces vulnerable to legal challenge under human rights legislation, particularly in cases in which starvation occurs as a result of a blockade.


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