Wings and halteres act as coupled dual-oscillators in flies

The mechanics of Dipteran thorax is dictated by a network of exoskeletal linkages which, when deformed by the flight muscles, generate coordinated wing movements. In Diptera, the forewings power flight, whereas the hindwings have evolved into specialized structures called halteres which provide rapid mechanosensory feedback for flight stabilization. Although actuated by independent muscles, wing and haltere motion is precisely phase-coordinated at high frequencies. Because wingbeat frequency is a product of wing-thorax resonance, any wear-and-tear of wings or thorax should impair flight ability. How robust is the Dipteran flight system against such perturbations? Here, we show that wings and halteres are independently-driven, coupled oscillators. We systematically reduced the wing length in flies and observed how wing-haltere synchronization was affected. The wing-wing system is a strongly-coupled oscillator, whereas the wing-haltere system is weakly-coupled through mechanical linkages which synchronize phase and frequency. Wing-haltere link acts in a unidirectional manner; altering wingbeat frequency affects haltere frequency, but not vice-versa. Exoskeletal linkages are thus key morphological features of the Dipteran thorax which ensure wing-haltere synchrony, despite severe wing damage.

Stabilizing responses to sideslip disturbances in Drosophila melanogaster are modulated by the density of moving elements on the ground

Stabilizing responses to sideslip disturbances are a critical part of the flight control system in flies. While strongly mediated by mechanoreception, much of the final response results from the wide-field motion detection system associated with vision. In order to be effective, these responses must match the disturbance they are aimed to correct. To do this, flies must estimate the velocity of the disturbance, although it is not known how they accomplish this task when presented with natural images or dot fields. The recent finding, that motion parallax in dot fields can modulate stabilizing responses only if perceived below the fly, raises the question of whether other image statistics are also processed differently between eye regions. One such parameter is the density of elements moving in translational optic flow. Depending on the habitat, there might be strong differences in the density of elements providing information about self-motion above and below the fly, which in turn could act as selective pressures tuning the visual system to process this parameter on a regional basis. By presenting laterally moving dot fields of different densities we found that, in Drosophila melanogaster , the amplitude of the stabilizing response is significantly affected by the number of elements in the field of view. Flies countersteer strongly within a relatively low and narrow range of element densities. But this effect is exclusive to the ventral region of the eye, and dorsal stimuli elicit an unaltered and stereotypical response regardless of the density of elements in the flow. This highlights local specialization of the eye and suggests the lower region may play a more critical role in translational flight stabilization.

The Design and Implementation of a Custom Platform for the Experimental Tuning of a Quadcopter Controller

This paper describes the development process of the quadcopter-based unmanned flying platform, designed for testing and experimentation purposes. The project features custom-made hardware, which includes the prototype quadcopter frame and the flight controller, and software solutions, such as control loop setup. The article specifies the controller tuning used for the initialization of the flight stabilization system and presents the final results of the quadcopter performance evaluation.

The coupled dual-oscillator model of wing and haltere motion in flies

The mechanics of Dipteran thorax is dictated by a network of exoskeletal linkages which, when deformed by flight muscles, generate coordinated wing movements. In Diptera, forewings power flight, whereas hindwings have evolved into specialized halteres which provide rapid mechanosensory feedback for flight stabilization. Although actuated by independent muscles, wing-haltere motion is precisely phase-coordinated at high frequencies. Because wingbeat frequency is a product of wing-thorax resonance, wear-and-tear of wings or thorax should impair flight ability. Here, we show that wings and halteres are independently-driven, linked, coupled oscillators. We systematically reduced wing length in flies and observed how wing-haltere synchronization was affected. The wing-wing system is a strongly-coupled oscillator, whereas wing-haltere system is weakly-coupled through mechanical linkages which synchronize phase and frequency. Wing-haltere link is unidirectional; altering wingbeat frequency affects haltere frequency, but not vice-versa. Exoskeletal linkages are thus key morphological features of Dipteran thorax, ensuring robust wing-haltere synchrony despite wing damage.

Spatial orientation based on multiple visual cues in monarch butterflies

Monarch butterflies (Danaus plexippus) are prominent for their annual long-distance migration from North America to its overwintering area in Central Mexico. To find their way on this long journey, they use a sun compass as their main orientation reference but will also adjust their migratory direction with respect to mountain ranges. This indicates that the migratory butterflies also attend to the panorama to guide their travels. Here we studied if non-migrating butterflies - that stay in a more restricted area to feed and breed - also use a similar compass system to guide their flights. Performing behavioral experiments on tethered flying butterflies in an indoor LED flight simulator, we found that the monarchs fly along straight tracks with respect to a simulated sun. When a panoramic skyline was presented as the only orientation cue, the butterflies maintained their flight direction only during short sequences suggesting that they potentially use it for flight stabilization. We further found that when we presented the two cues together, the butterflies register both cues in their compass. Taken together, we here show that non-migrating monarch butterflies can combine multiple visual cues for robust orientation, an ability that may also aid them during their migration.SummaryNon-migrating butterflies keep directed courses when viewing a simulated sun or panoramic scene. This suggest that they orient based on multiple visual cues independent of their migratory context.

Pomiary wysokości i prędkości lotu małego samolotu bezzałogowego z wykorzystaniem rurek Prandtla

Reliable measurements of the air velocity flowing around the wings of the aircraft and the altitude at which the aircraft is located are necessary for controlling the unmanned aircraft. Due to the need to use automatic flight stabilization processes, unmanned aircraft require a minimal delay in the measuring path. For correct measurement of these quantities, a system based on two measuring lines using backflow tubes was built. This article describes the effects of a research project carried out by the Student Scientific Group of Electronics at the Rzeszów University of Technology, who were seeking a reliable and quick solution with increased accuracy.

Neuronal ON/OFF Motion Detection Circuits Underlying Looming-Evoked Escape Behavior in Drosophila

In Drosophila, early visual processing of motion information segregates in separate ON and OFF pathways. These pathways have been studied in the context of local directional motion detection leading to the encoding of optic flow that provides visual information for flight stabilization. Less is known about their role in detecting impending collision and generating escape behaviors. ‘Looming’, the simulated approach of an object at constant speed towards an animal, provides a powerful stimulus eliciting jump escape behaviors in stationary flies. We presented looming stimuli mimicking the approach of either a dark object on a bright background or a light object on a dark background, while inactivating neurons belonging either to the ON- or the OFF-motion detection pathways by expressing the dominant Drosophila temperature-sensitive mutant shibirets in different cells of the ON/OFF pathway. Inactivation of ON, respectively OFF, neurons led to selective decreases in escape behavior to light, resp. dark, looming stimuli. Quantitative analysis showed a nearly perfect splitting of these effects according to the ON/OFF type of the targeted neural populations. Our results suggest that Drosophila ON/OFF motion detection pathways play an important role in controlling jump escape responses according to looming stimulus polarity. They further imply that the biophysical circuits triggering Drosophila jump escape behaviors likely differ substantially from those characterized in other arthropods.SummaryInactivating fly neurons of the ON or OFF directional motion detection pathways during escape behavior selectively reduced jump responses to light and dark looming stimuli, respectively.