scholarly journals Gravity and active acceleration limit the ability of killer flies ( Coenosia attenuata ) to steer towards prey when attacking from above

2021 ◽  
Vol 18 (178) ◽  
pp. 20210058
Author(s):  
S. Rossoni ◽  
S. T. Fabian ◽  
G. P. Sutton ◽  
P. T. Gonzalez-Bellido
Keyword(s):  
Selective Pressure ◽  
Lateral Acceleration ◽  
Proportional Navigation ◽  
Flight Duration ◽  
Coenosia Attenuata ◽  
Initial Geometry

Insects that predate aerially usually contrast prey against the sky and attack upwards. However, killer flies ( Coenosia attenuata ) can attack prey flying below them, performing what we term ‘aerial dives'. During these dives, killer flies accelerate up to 36 m s −2 . Although the trajectories of the killer fly's dives appear highly variable, proportional navigation explains them, as long as the model has the lateral acceleration limit of a real killer fly. The trajectory's steepness is explained by the initial geometry of engagement; steep attacks result from the killer fly taking off when the target is approaching the predator. Under such circumstances, the killer fly dives almost vertically towards the target, and gravity significantly increases its acceleration. Although killer flies usually time their take-off to minimize flight duration, during aerial dives killer flies cannot reach the lateral accelerations necessary to match the increase in speed caused by gravity. Since a close miss still leads the predator closer to the target, and might even slow the prey down, there may not be a selective pressure for killer flies to account for gravity during aerial dives.

Minimizing manoeuvre advantage requirements for a hit-to-kill interceptor

2005 ◽  
Vol 219 (2) ◽  
pp. 113-129
Author(s):  
T L Vincent ◽  
R G Cottrell ◽  
R W Morgan
Keyword(s):  
Time Constant ◽  
Flight Control ◽  
Initial Conditions ◽  
Estimation Error ◽  
Two Dimensions ◽  
Lateral Acceleration ◽  
Proportional Navigation ◽  
Guidance Law ◽  
Optimal Guidance ◽  
Wide Range

Hit-to-kill requires extremely high intercept accuracies. Such performance places severe demands on interceptor manoeuvrability and flight control response time constant when engaging targets that are intentionally or unintentionally manoeuvring. A well-known guidance law for use against a manoeuvring target is augmented proportional navigation (APN). It is an optimal guidance law under various assumptions including a constant-lateral-acceleration target. It is also effective when used against other target manoeuvres provided that the lateral acceleration capabilities of the interceptor is significantly greater than the lateral acceleration capabilities of the target, and if the time constant of the interceptor flight control system is small. The advantage of using a new guidance algorithm for a hit-to-kill interceptor against a manoeuvring target in two dimensions is demonstrated in this paper. A large manoeuvre advantage is not required, and it is effective with time constants that would otherwise degrade the performance of APN. Results are based on a two-dimensional non-linear model with the target performing a weave manoeuvre. The new algorithm can achieve increased intercept accuracy under minimal manoeuvre advantage requirements over a wide range of initial conditions with reasonable levels of angle noise and target manoeuvre estimation error.

Estimation of target lateral acceleration for Augmented Proportional Navigation

1997 ◽  
Author(s):  
B. Boberg ◽  
J. Lundberg ◽  
J. Wiberg ◽  
S.-L. Wirkander ◽  
B. Boberg ◽  
...  
Keyword(s):  
Lateral Acceleration ◽  
Proportional Navigation

scholarly journals A New Optimal Guidance Law with Impact Time and Angle Constraints Based on Sequential Convex Programming

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Pei Pei ◽  
Jiang Wang
Keyword(s):  
Convex Programming ◽  
Optimization Problem ◽  
Impact Angle ◽  
Lateral Acceleration ◽  
Optimal Time ◽  
Proportional Navigation ◽  
Impact Time ◽  
Guidance Law ◽  
Sequential Convex Programming ◽  
Optimal Guidance

This paper proposed an optimal time-varying proportional navigation guidance law based on sequential convex programming. The guidance law can achieve the desired impact angle and impact time with look angle and lateral acceleration constraints. By treating the multiconstraints’ guidance problem as an optimization problem and changing the independent variable to linearize the problem and constraints, the original nonlinear and nonconvex problem is transformed into a series of convex optimization problem so that it can be quickly solved by sequential convex programming. Numerical simulations compared to nonlinear programming and traditional analytical guidance law demonstrate the effectiveness and efficiency of the proposed algorithm. Finally, the proposed guidance law is verified to satisfy different impact time periods and impact angle constraints.

scholarly journals Interception by two predatory fly species is explained by a proportional navigation feedback controller

2018 ◽  
Vol 15 (147) ◽  
pp. 20180466 ◽  
Author(s):  
Samuel T. Fabian ◽  
Mary E. Sumner ◽  
Trevor J. Wardill ◽  
Sergio Rossoni ◽  
Paloma T. Gonzalez-Bellido
Keyword(s):  
Time Delay ◽  
Feedback Controller ◽  
Three Dimensions ◽  
Proportional Navigation ◽  
Control Effort ◽  
Rotation Rates ◽  
Time Optimal ◽  
Pure Pursuit ◽  
Coenosia Attenuata ◽  
Simple Feedback

When aiming to capture a fast-moving target, animals can follow it until they catch up, or try to intercept it. In principle, interception is the more complicated strategy, but also more energy efficient. To study whether simple feedback controllers can explain interception behaviours by animals with miniature brains, we have reconstructed and studied the predatory flights of the robber fly Holcocephala fusca and killer fly Coenosia attenuata . Although both species catch other aerial arthropods out of the air, Holcocephala contrasts prey against the open sky, while Coenosia hunts against clutter and at much closer range. Thus, their solutions to this target catching task may differ significantly. We reconstructed in three dimensions the flight trajectories of these two species and those of the presented targets they were attempting to intercept. We then tested their recorded performances against simulations. We found that both species intercept targets on near time-optimal courses. To investigate the guidance laws that could underlie this behaviour, we tested three alternative control systems (pure pursuit, deviated pursuit and proportional navigation). Only proportional navigation explains the timing and magnitude of fly steering responses, but with differing gain constants and delays for each fly species. Holcocephala uses a dimensionless navigational constant of N ≈ 3 with a time delay of ≈28 ms to intercept targets over a comparatively long range. This constant is optimal, as it minimizes the control effort required to hit the target. In contrast, Coenosia uses a constant of N ≈ 1.5 with a time delay of ≈18 ms, this setting may allow Coenosia to cope with the extremely high line-of-sight rotation rates, which are due to close target proximity, and thus prevent overcompensation of steering. This is the first clear evidence of interception supported by proportional navigation in insects. This work also demonstrates how by setting different gains and delays, the same simple feedback controller can yield the necessary performance in two different environments.

A Note on Maximum Flight Range and Maximum Flight Duration of Airplanes

2020 ◽  
Vol 68 (3) ◽  
pp. 123-127
Author(s):  
Shigeru Sunada ◽  
Ryoji Katayanagi ◽  
Kohei Yamaguchi
Keyword(s):  
Flight Duration ◽  
Flight Range

The Driving Severity Number (DSN) — A Step Toward Quantifying Treadwear Test Conditions

1986 ◽  
Vol 14 (3) ◽  
pp. 139-159 ◽  
Author(s):  
A. G. Veith
Keyword(s):  
Signal Processing ◽  
Ambient Temperature ◽  
Lateral Acceleration ◽  
Force Distribution ◽  
Single Index ◽  
Tire Force ◽  
Test Conditions ◽  
Wheel Revolution ◽  
High Degree ◽  
Revolution Counter

Abstract A system, called the “Driving Severity Monitor” (DSM), has been developed for characterizing tire force distribution as related to treadwear in either normal tire use or in tire fleet testing in a convoy. The system consists of an accelerometer for monitoring lateral accelerations, a wheel revolution counter, and a module for signal processing and read-out. The output of the DSM is reduced to a single index, the Driving Severity Number (DSN), which characterizes a vehicle journey. The DSN is equal to the sum of squares of lateral acceleration measured once per tire revolution during a trip, divided by the number of wheel revolutions. The DSN had a high degree of correlation (R ≧ 0.95) with treadwear in two wear programs when pavement abrasiveness was held constant. This supports the concept that the three basic treadwear components: tire force distribution, pavement abrasiveness, and ambient temperature, can be separated for better understanding of tire treadwear.

Study of Alnus incana L. Moench fruit extract biologically active substances influence on resistance development in mls-resistant staphylococci skin isolates

2018 ◽  
Vol 22 (2) ◽  
pp. 263-266
Author(s):  
R.V. Kutsyk ◽  
O.I. Yurchyshyn
Keyword(s):  
Selective Pressure ◽  
Biological Response ◽  
Biologically Active Substances ◽  
Biologically Active ◽  
Alnus Incana ◽  
Fruit Extract ◽  
Antimicrobial Drugs ◽  
Resistance Development ◽  
Subinhibitory Concentrations ◽  
Active Substances

The emergence of microorganisms resistant strains is a natural biological response to the use of antimicrobial drugs that creates selective pressure, contributing to pathogens selection, survival and reproduction. The purpose of the investigation was to study the resistance development of staphylococci skin isolates to erythromycin and influence on it Alnus incana L. fruit extract subinhibitory concentrations. Development of resistance to erythromycin and influence on it Alnus incana L. fruit extract (extraction by 90% ethanol) subinhibitory concentrations were conducted with S epidermidis strains: sensitive and resistant to 14 and 15-membered macrolides. The study was carried out within 30 days by multiple consecutive passages of staphylococci test strains (concentration 1×107 CFU/ml) into test tubes containing broth and erythromycin ranging from 3 doubling dilutions above to doubling dilutions below the minimum inhibitory concentration. Statistical analysis of the results was carried out by one-and two-factor analysis of variance (ANOVA) and Microsoft Office Excel 2011. Rapid increase of resistance from 32 to 1024 μg/ml (F=34.2804; F> Fstand. max = 5.9874; p=0.0011) for S.epidermidis with a low level of resistance to 14 and 15-membered macrolides resistance to the erythromycine was observed. In the presence of Alnus incana L. fruit extract subinhibitory concentrations (¼ MIC), the initial MIC of erythromycin was decreased by 32 times to 1 μg/ml (F = 9.7497; F> Fstand. max = 5.9874; p = 0.0205). The sensitive strain after 30 passages did not develop resistance to erythromycin. Under the influence of erythromycin selective pressure, S.epidermidis strain with low initial level of MLS-resistance rapidly reaches a high-level resistance. Biologically active substances of the Alnus incana L. fruit extract significantly inhibit the resistance development in S. epidermidis to macrolides and eliminate it phenotypic features.

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