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In this paper, we propose Lyapunov theory-based nonlinear guidance scheme to achieve an angle-constrained interception of a high-speed target (targets with speed advantage). An impact angle based classification between head-on and head-pursuit interception geometries is first proposed to uniquely match a desired impact angle to a corresponding desired line-of-sight (LOS) angle for successful target interception. The proposed guidance scheme comprises two phases, namely orientation and LOS tracking phases. The orientation phase corrects the interceptor's lead angle based on the desired interception geometry whenever required. The LOS tracking phase then enables the tracking of desired LOS angle by enforcing the error is LOS angle to converge onto a manifold with finite-time convergent properties. The applicability of the proposed guidance strategy is validated using numerical simulations for various engagement geometries, in the presence of autopilot, for constant speed as well as time-varying speed interceptors. The performance of the proposed guidance scheme is also compared with existing ones against high-speed targets, and is found to be superior. [ABSTRACT FROM AUTHOR]

We propose predefined-time consensus-based cooperative guidance laws for a swarm of interceptors to simultaneously capture a target capable of executing various kinds of motions. Unlike leader-follower cooperative guidance techniques, the swarm of interceptors has no leader and each interceptor executes its own guidance command in a distributive fashion, thus obviating the residency of the mission over a single interceptor. We first design cooperative guidance commands subject to target's mobility, followed by the same when the target is stationary, and also account for interceptors' changing topologies. We further show through rigorous analysis that the proposed cooperative guidance laws guarantee consensus in the interceptors' time-to-go values within a predefined-time. The proposed design allows a feasible time of consensus in time-to-go to be set arbitrarily at will during the design regardless of the interceptors' initial time-to-go values, thereby ensuring a simultaneous target interception. We also demonstrate the efficacy of the proposed design via simulations for interceptors connected over static and dynamic networks. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of controlling impact time against various types of target – stationary, constant velocity, or maneuvering. Analytical expression of time-to-go, that is exact for non-maneuvering target but approximate for maneuvering ones, is first presented based on true-proportional-navigation guidance concepts. Guidance strategies are then derived, using Lyapunov theory, to meet impact time constraints, without linearizing the engagement dynamics. Hence, the proposed strategies remain effective even for large initial heading errors. Further, a cooperative guidance strategy to achieve simultaneous target interception by multiple interceptors is also proposed. Guidance commands that ensure consensus among the time-to-go values of the interceptors are utilized for this purpose. Using judicious choices of gains, the common time of target interception may be either pre-fixed, or the same may be decided cooperatively during the engagement. Stability analysis of the possible equilibria in heading angle dynamics, for different choices of parameters, is also performed. For both one-to-one and cooperative homing, simulation results are presented for various engagement scenarios to demonstrate the effectiveness of the proposed strategies. [ABSTRACT FROM AUTHOR]

This work proposes two different cooperative integrated guidance and control schemes for a group of interceptors, each steered by combined effects of canard and tail aerodynamic surfaces, aiming a simultaneous interception of a non-maneuvering target. The first approach is based on a leader-follower framework, in which the time of interception can be prescribed before homing, while the second approach is of a leaderless framework, in which the time of interception is decided during engagement. The proposed integrated guidance and control design for multi-body engagement is carried out under nonlinear settings, with time-to-go formulations that relax the restrictive assumption of interceptors' small heading angles. This facilitates wide applicability of the proposed design in scenarios necessitating large terminal time requirements. In addition to the nonlinearity in kinematics of engagement and interceptors' dynamics, effect of actuators are also considered, making the design suitable for practical implementation. Since canard and tail aerodynamic surfaces have different capabilities, a weighted effort allocation scheme is devised to apportion the total effort in both control surfaces in a suitable manner. Finally, various engagement scenarios have been considered in simulations to substantiate the efficacy of the proposed schemes. [ABSTRACT FROM AUTHOR]

In this paper, a nonlinear suboptimal three-dimensional guidance strategy based on a finite-time state-dependent Riccati equation technique is proposed to achieve interception of a non-maneuvering target at a desired impact time. To design the proposed guidance, range error for a spatial engagement between an interceptor and non-maneuvering target is introduced as the difference between the desired range-to-go and range-to-go of the predicted interception point. It is shown that forcing the range error and its rate to the origin are sufficient to achieve impact time constrained interception. Several existing impact time guidance strategies require a time-to-go estimate, to implement their guidance command, which may become erroneous in the presence of measurement noise and affect their performance. However, the proposed guidance does not require any such time-to-go estimate in its design process. Furthermore, guidance for the case of planar engagements is shown to be a special case of the proposed guidance scheme. Finally, numerical simulation studies for multiple engagement geometries, along with a comparison study with an existing strategy, are provided to demonstrate the efficacy of the proposed technique. [ABSTRACT FROM AUTHOR]

This paper proposes integrated guidance and control design to intercept a target, which may execute various motions, at a pre-specified time of interception. The problem is addressed considering nonlinear engagement kinematics and the interceptor is steered using the combined effects of canard as well as tail configurations (dual-controlled interceptors). Different formulations of time-to-go, without the restrictive assumption of interceptor's small heading angle, have been used in deriving the guidance commands, allowing the proposed strategy to remain effective over a wide range of impact time values. A weighted effort allocation scheme, in canard and tail deflections, has been proposed to generate the required lateral acceleration. The overall design uses sliding mode control owing to its simplicity of design, while a nonlinear finite-time disturbance observer is used to estimate the target's maneuver. Finally, simulations are presented for various target motions, and time-constrained interception with an impaired actuator is also shown, vindicating the efficacy of the proposed technique. [ABSTRACT FROM AUTHOR]

This paper deals with nonsingular guidance and control design for an interceptor, using a decoupled approach, steered by the combined effects of both canard and tail, to intercept a moving but non-maneuvering target at a time specified a priori. First, interceptor's desired lateral acceleration, consisting of nominal and corrective components, is derived using deviated pursuit guidance. While the nominal component is the pursuit guidance law, the corrective component drives the time-to-go error to zero within a finite-time in an optimal manner. Using a desired error dynamics and a meaningful performance index, the lateral acceleration demand is minimized during the transient phase. With exact knowledge of time-to-go and the consideration of nonlinear kinematic model, the proposed design circumvents the errors arising out of any approximations. Interceptor's canard and tail deflection commands are derived using predefined-time convergent sliding mode control, which allows the autopilot to precisely track the commanded lateral acceleration within a time specified during design. Finally, simulations are presented for various cases to demonstrate the efficacy of the proposed design. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of maximizing the warhead effectiveness, by achieving impact at the structurally vulnerable points of the targets. The impact direction is first defined using target frame, and then a unique relation between the desired impact angles and the desired line-of-sight angles is derived. Using this relation, two nonlinear guidance strategies, based on finite-time sliding mode and optimal control methods, are proposed to achieve interception of maneuvering targets at a pre-specified desired impact orientation. Unlike most of the existing three-dimensional guidance strategies, the proposed guidance strategies are derived without decoupling nonlinear coupled engagement kinematics into two mutually orthogonal planes and performing linearization, thereby avoiding possible performance deterioration for engagement with large heading errors. The performances of proposed guidance strategies are evaluated for various engagement geometries as well as constant speed and different realistic time-varying speed pursuer models subjected to aerodynamics parameter variations, and found to be satisfactory. [ABSTRACT FROM AUTHOR]

This paper presents a novel nonlinear guidance law for an autonomous unmanned aerial vehicle (UAV) that enables it to track any predefined path while taking into account wind effects. The approach involves treating the desired path as the trajectory of the virtual target, which the UAV tracks without relying on knowledge of the path's curvature. This makes the design applicable to paths with varying levels of complexity and smooth curvatures. Additionally, the proposed method draws inspiration from pursuit guidance, known for its simplicity and ease of implementation. Theoretical analysis ensures that the UAV will converge to the intended path within a fixed time, irrespective of its initial configuration relative to the path. Simulations demonstrate the effectiveness of the proposed method, showcasing the UAV's ability to accurately follow diverse curvilinear paths. [ABSTRACT FROM AUTHOR]

This paper proposes a polynomial-based three-dimensional (3D) impact angle-constrained guidance law considering the seeker's field-of-view (FOV) bound. The guidance laws are derived using nonlinear coupled dynamics of the interceptor-target engagement against stationary as well as constant velocity targets. Line-of-sight (LOS) orientations between the interceptor and the target in both pitch and yaw planes are shaped as two cubic polynomial functions of relative range. An explicit expression for the look angle of the interceptor is acquired in terms of the LOS polynomials. This expression facilitates the embodiment of the FOV constraint in the boundary conditions inflicted on the polynomials. A system of equations with the eight unknown coefficients is obtained by employing the appropriate launch and terminal conditions of the interceptor-target engagement. Reference LOS angle and lead angle profiles are generated using the calculated coefficients, complying to which the interceptor achieves a zero miss distance with desired impact angle and FOV constraints. A tracking controller is then designed using a nonlinear control technique that enables the interceptor to follow reference lead angle profiles in mutually orthogonal planes. Unlike the already existing guidance strategies for 3D impact angle and FOV-constrained target interception, the proposed nonlinear guidance strategy is designed without the use of linearization or decoupling. Moreover, no switching logic or multi-phase guidance structures are employed in the proposed guidance strategy, which eliminates possible jumps in the guidance command. The effectiveness of the proposed guidance law is validated using numerical simulations, along with a comparison study with the existing strategy. [ABSTRACT FROM AUTHOR]

In this paper, proportional derivative control has been explored further to devise dynamic velocity error-based controller for trajectory tracking of space robotic manipulator. The dynamic velocity error is defined using the difference between current velocity and dynamic desired velocity, which is calculated based on the current position and successive desired position. The dynamic velocity error-based controller consists only of the derivative term, unlike conventional proportional derivative control which consists of both proportional as well as derivative terms. Although proposed dynamic velocity error-based controller is simple and robust, the modified versions of direct and indirect adaptive controllers are also presented utilizing dynamic velocity error to handle external disturbances and internal uncertainties in non linear dynamics. Lyapunov theory is employed to prove the stability of the closed-loop system. The main advantage of the dynamic velocity error based controller is that it is as simple as a proportional derivative controller and as robust as adaptive controllers. Finally, the effectiveness of the proposed control designs is validated using numerical simulations, and a comparative study of various control designs has also been provided to substantiate the claims further. [ABSTRACT FROM AUTHOR]