scholarly journals Attack behaviour in naïve Gyrfalcons is modelled by the same guidance law as in Peregrines, but at a lower guidance gain

2021 ◽  
pp. jeb.238493
Author(s):  
Caroline H. Brighton ◽  
Katherine E. Chapman ◽  
Nicholas C. Fox ◽  
Graham K. Taylor
Keyword(s):  
High Speed ◽  
Angular Rate ◽  
Species Level ◽  
Line Of Sight ◽  
Proportional Navigation ◽  
Evolutionary Origins ◽  
Guidance Law ◽  
Flight Morphology ◽  
Aerial Hunting ◽  
The Individual

The aerial hunting behaviours of birds are strongly influenced by flight morphology and ecology, but little is known of how this relates to the behavioural algorithms guiding flight. Here we use GPS loggers to record the attack trajectories of captive-bred Gyrfalcons (Falco rusticolus) during their maiden flights against robotic aerial targets, which we compare to existing flight data from Peregrines (Falco peregrinus). The attack trajectories of both species are well modelled by a proportional navigation (PN) guidance law, which commands turning in proportion to the angular rate of the line-of-sight to target, at a guidance gain. However, naïve Gyrfalcons operate at significantly lower values of N than Peregrines, producing slower turning and a longer path to intercept. Gyrfalcons are less manoeuvrable than Peregrines, but physical constraint is insufficient to explain the lower values of N we found, which may reflect either the inexperience of the individual birds or ecological adaptation at the species level. For example, low values of N promote the tail-chasing behaviour that is typical of wild Gyrfalcons and which apparently serves to tire their prey in a prolonged high-speed pursuit. Likewise, during close pursuit of typical fast evasive prey, PN will be less prone to being thrown off by erratic target manoeuvres at low guidance gain. The fact that low-gain PN successfully models the maiden attack flights of Gyrfalcons suggests that this behavioural algorithm is embedded in a guidance pathway ancestral to the clade containing Gyrfalcons and Peregrines, though perhaps with much deeper evolutionary origins.

scholarly journals Attack behaviour in naïve Gyrfalcons is modelled by the same guidance law as in Peregrines, but at a lower guidance gain

2020 ◽  
Author(s):  
Caroline H. Brighton ◽  
Katherine E. Chapman ◽  
Nicholas C. Fox ◽  
Graham K. Taylor
Keyword(s):  
High Speed ◽  
Angular Rate ◽  
Line Of Sight ◽  
Proportional Navigation ◽  
Flight Data ◽  
Guidance Law ◽  
Flight Morphology ◽  
Summary Statement ◽  
Aerial Hunting ◽  
Proportional Navigation Guidance

ABSTRACTThe aerial hunting behaviours of birds are strongly influenced by their flight morphology and ecology, but little is known of how this variation relates to the behavioural algorithms guiding flight. Here we use onboard GPS loggers to record the attack trajectories of captive-bred Gyrfalcons (Falco rusticolus) during their maiden flights against robotic aerial targets, which we compare to existing flight data from Peregrines (Falco peregrinus) The attack trajectories of both species are modelled most economically by a proportional navigation guidance law, which commands turning in proportion to the angular rate of the line-of-sight to target, at a guidance gain N. However, Gyrfalcons operate at significantly lower values of N than Peregrines, producing slower turning and a longer path to intercept. Gyrfalcons are less agile and less manoeuvrable than Peregrines, but this physical constraint is insufficient to explain their lower guidance gain. On the other hand, lower values of N promote the tail-chasing behaviour that is typical of wild Gyrfalcons, and which apparently serves to tire their prey in a prolonged high-speed pursuit. Moreover, during close pursuit of fast evasive prey such as Ptarmigan (Lagopus spp.), proportional navigation will be less prone to being thrown off by erratic target manoeuvres if N is low. The fact that low-gain proportional navigation successfully models the maiden attack flights of Gyrfalcons suggests that this behavioural algorithm is embedded in a hardwired guidance loop, which we hypothesise is ancestral to the clade containing Gyrfalcons and Peregrines.SUMMARY STATEMENTNaïve Gyrfalcons attacking aerial targets are modelled by the same proportional navigation guidance law as Peregrines, but with a lower navigation constant that promotes tail-chasing rather than efficient interception.

scholarly journals Novel adaptive sliding mode guidance law against arbitrarily maneuvering target

2019 ◽  
Vol 11 (11) ◽  
pp. 168781401988639
Author(s):  
Xuan-Ping Liao ◽  
Jing Zhang ◽  
Ke-Bo Li ◽  
Lei Chen
Keyword(s):  
Upper Bound ◽  
Sliding Mode ◽  
Angular Rate ◽  
Convergence Time ◽  
Line Of Sight ◽  
Proportional Navigation ◽  
Adaptive Estimator ◽  
Adaptive Sliding Mode ◽  
Guidance Law ◽  
Target Acceleration

A novel adaptive sliding mode guidance law is proposed in this article. The target is assumed to have an arbitrarily but upper bounded maneuvering acceleration which is considered as the system disturbances and uncertainties. The guidance law is consisted of three terms. The first one is a proportional navigation–type term. The second one is a term used for compensating the target maneuvering acceleration. And the last one is a term for controlling the convergence time of the line-of-sight angular rate. In this guidance law, the upper bound of the target acceleration is estimated by an adaptive estimator with a tunable updating law. Hence, the prior knowledge of the upper bound of the target acceleration is not essential for this guidance law. The novel adaptive sliding mode guidance law can guarantee the asymptotical convergence of the line-of-sight rate to zero or its neighborhood, or even the finite time convergence of the line-of-sight rate conditionally. Finally, the new theoretical findings are demonstrated by numerical simulations.

Improved sliding mode guidance law based on fuzzy variable coefficients strategy

2014 ◽  
Vol 118 (1202) ◽  
pp. 435-451 ◽  
Author(s):  
J.H. Xiong ◽  
S.J. Tang ◽  
J. Guo ◽  
T.N. Wang
Keyword(s):  
Sliding Mode ◽  
Angular Rate ◽  
Fuzzy Variable ◽  
Fuzzy Rule ◽  
Variable Coefficients ◽  
Line Of Sight ◽  
Proportional Navigation ◽  
Adaptive Sliding Mode ◽  
Guidance Law ◽  
Proportional Navigation Law

AbstractAn adaptive sliding mode guidance law guiding the line-of-sight angular rate to converge to zero was highly appraised. However, compared with the conventional proportional navigation law, adaptive sliding mode guidance law leads to large acceleration demand of the interceptor before the line-of-sight angular rate converging to zero, especially in a situation where the target has strong manoeuvrability as well as high velocity. In this paper, a strategy making the coefficients of the guidance law vary according to a fuzzy rule is proposed. Smaller guidance coefficients are selected at the beginning of the terminal guidance. Therefore, the guidance command is reduced and a smaller acceleration of the interceptor is incurred. As the coefficients grow to the fixed and desired values, the line-of-sight angular rate converges to zero rapidly, so that the convergence to the sliding surface is guaranteed. It is concluded that the fuzzy variable coefficients strategy is highly effective for tail-chase, head-on interception and head pursuit engagements as shown in the simulations.

Impact-angle-constrained reentry guidance law guaranteeing convergence before attainment of desired line-of-sight range

2018 ◽  
Vol 233 (8) ◽  
pp. 2783-2791
Author(s):  
Chunwang Jiang ◽  
Guofeng Zhou ◽  
Rui Lv ◽  
Haifeng Tu ◽  
Fengjun Yang ◽  
...  
Keyword(s):  
Angular Rate ◽  
Impact Angle ◽  
Line Of Sight ◽  
The Novel ◽  
Proportional Navigation ◽  
Stationary Target ◽  
Guidance Law ◽  
Ground Impact ◽  
Impact Angle Constraint ◽  
Guidance Model

For reentry vehicle attacking a stationary target on the ground, impact-angle-constrained guidance law guaranteeing convergence before attainment of desired line-of-sight range is studied in this paper. Initially, a novel guidance model is established, in which line-of-sight range is treated as an independent variable, describing the relative motion between the vehicle and the target. Subsequently, a guidance law with impact angle constraint is designed based on the guidance model, which is presented in the form of normal overload. Compared with traditional guidance laws, the proposed one guarantees line-of-sight angular rate converges to zero and line-of-sight angle converges to the commanding impact angle before line-of-sight range decreases to the desired value. Finally, comparisons among proportional navigation guidance, optimal navigation guidance, and the proposed guidance are carried out by numerical simulation, which demonstrate the correctness and advantage of the novel guidance model and guidance law. The guidance model and guidance law proposed in this paper provide a new way for the design of fast convergent guidance law with impact angle constraint.

Performance analysis of differential geometric guidance law against high-speed target with arbitrarily maneuvering acceleration

2018 ◽  
Vol 233 (10) ◽  
pp. 3547-3563 ◽  
Author(s):  
Ke-Bo Li ◽  
Wen-Shan Su ◽  
Lei Chen
Keyword(s):  
High Speed ◽  
Control System Design ◽  
Proportional Navigation ◽  
Full Account ◽  
Guidance And Control ◽  
Maneuvering Target ◽  
Guidance Law ◽  
Classical Differential Geometry ◽  
Relative Dynamics ◽  
And Control

The interception of high-speed target with an arbitrary maneuvering acceleration causes serious troubles to the guidance and control system design of airborne missile. A novel guidance law based on the classical differential geometry curve theory was proposed not long ago. Although it is believed and numerically demonstrated that this differential geometric guidance law (DGGL) is superior to the classical pure proportional navigation (PPN) in intercepting high-speed targets, its performance has not been thoroughly analyzed. In this paper, using the Lyapunov-like approach, the performance of DGGL against the high-speed target with an arbitrary but upper-bounded maneuvering acceleration is well studied. The upper bounds of the LOS rate and commanded acceleration of DGGL are obtained, and conditions that guarantee the capture of this type of maneuvering target are also presented. The nonlinear relative dynamics between the missile and target is taken into full account. Finally, the proposed theoretical findings are demonstrated by numerical simulation examples.

scholarly journals Controllers to Chase a High-Speed Evader Using a Pursuer with Variable Speed

2018 ◽  
Vol 8 (10) ◽  
pp. 1976 ◽  
Author(s):  
Jonghoek Kim
Keyword(s):  
Optical Flow ◽  
High Speed ◽  
Angular Rate ◽  
Relative Distance ◽  
Line Of Sight ◽  
Terminal Phase ◽  
Relative Speed ◽  
Variable Speed

This paper proposes a chasing controller to enable a pursuer to chase a high-speed evader such that the relative distance between the evader and the pursuer monotonically decreases as time passes. Our controller is designed to assure that the angular rate of Line-of-Sight joining the pair (the pursuer and the evader) is exactly zero at all time indexes. Assuming that the pursuee can readily observe optical flow, but only poorly detect looming, this pursuer’s movement is hardly detected by the pursuee. Consider the terminal phase when the pursuer is sufficiently close to the evader. As we slow down the relative speed of the pursuer with respect to the evader, we can reduce the probability of missing the high-speed evader. Thus, our strategy is to make the pursuer decrease its speed in the terminal phase, while ensuring that the distance between the evader and the pursuer monotonically decreases as time passes. The performance of our controller is verified utilizing MATLAB simulations.

A generalized design method for three-dimensional guidance laws

2016 ◽  
Vol 231 (1) ◽  
pp. 47-60 ◽  
Author(s):  
Sheng Sun ◽  
Di Zhou ◽  
Jingyang Zhou ◽  
Kok Lay Teo
Keyword(s):  
Lyapunov Function ◽  
Sliding Mode ◽  
Three Dimensional ◽  
Line Of Sight ◽  
Generalized Function ◽  
Proportional Navigation ◽  
Guidance Law ◽  
Target Acceleration ◽  
Guidance Laws ◽  
Proportional Navigation Guidance

The true proportional navigation guidance law, the augmented proportional navigation guidance law, or the adaptive sliding-mode guidance law, is designed based on the planar target-to-missile relative motion dynamics. By a proper construction of a nonlinear Lyapunov function for the line-of-sight angular rates in the three-dimensional guidance dynamics, it is shown that the three guidance laws mentioned above are able to ensure the asymptotic convergence of the angular rates as they are directly applied to the three-dimensional guidance environment. Furthermore, considering the missile autopilot dynamics as a first-order lag, we design three-dimensional nonlinear guidance laws by using the backstepping technique for three cases: (1) the target does not maneuver; (2) the information of target acceleration can be acquired; and (3) the target acceleration is not available but its bound is known a priori. In the first step of the backstepping design of the control law, there is no need to cancel the nonlinear coupling terms in the three-dimensional guidance dynamics in such way that the final expressions of the proposed guidance laws are significantly simplified. Thus, the proposed nonlinear Lyapunov function for the line-of-sight angular rates is a generalized function for designing three-dimensional guidance laws. Simulation results of a missile interception mission show that the proposed guidance laws are highly effective.

Non-linear missile guidance synthesis using control Lyapunov functions

2005 ◽  
Vol 219 (2) ◽  
pp. 77-87 ◽  
Author(s):  
P Gurfil
Keyword(s):  
Lyapunov Functions ◽  
Three Dimensional ◽  
Performance Measure ◽  
Line Of Sight ◽  
Missile Guidance ◽  
Proportional Navigation ◽  
Guidance Law ◽  
Non Linear ◽  
Non Linear Systems ◽  
Fixed Line

This paper derives a new non-linear guidance law aimed at interception of highly manoeuvring targets. The guidance law is developed based on the theory of control Lyapunov functions (CLFs), a methodology for universal stabilization of non-linear systems which is also inverse optimal with respect to some performance measure. The three-dimensional guidance dynamics are formulated in a fixed-line-of-sight coordinate system, yielding matching between the target and missile accelerations. Closed-form expressions for the CLF guidance commands are given. Simulation shows that the new guidance scheme significantly outperforms augmented proportional navigation in short-range engagements.

A finite-time-convergent composite guidance law with strong fault-tolerant performance

2018 ◽  
Vol 233 (9) ◽  
pp. 3120-3130 ◽  
Author(s):  
Feng Chen ◽  
Guangjun He ◽  
Qifang He
Keyword(s):  
Finite Time ◽  
Fault Tolerant ◽  
Sliding Mode ◽  
Angular Rate ◽  
Gain Coefficient ◽  
High Gain ◽  
Line Of Sight ◽  
Practical Implementation ◽  
Integral Sliding Mode ◽  
Guidance Law

To improve the performance of tracking and intercepting the low-altitude target, a nonlinear integral sliding mode guidance law is designed firstly, which can guarantee that the line-of-sight angle converges to a desired tracking angle and the line-of-sight angular rate converges to zero in finite time. Meanwhile, to solve the chattering problem caused by the high gain coefficient of the sign function in the guidance law, a sliding mode disturbance observer is designed to estimate the maneuvering acceleration of the target. Moreover, a composite nonlinear integral sliding mode guidance law is designed by introducing the estimated value of the acceleration, which can weaken the chattering phenomenon effectively. Finally, considering the magnitude loss fault of the guidance command that may occur in the practical implementation, a composite guidance law with strong fault-tolerant performance is designed by introducing a fault compensation command, which can effectively improve the reliability of the system.

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