Modern Midcourse Guidance Laws in the Endoatmosphere

Jalali-Naini, Seyed Hamid; Pourtakdoust, Seid H.

doi:10.2514/6.2005-6291

Cited by 4 publications

(6 citation statements)

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“…Th e interceptor desired velocity v * is the velocity that makes ZEM equal to zero. Th is desired velocity is referred to as generalized required velocity (Jalali-Naini and Pourtakdoust 2005). Th e interceptor dynamics is, here, assumed to be perfect, the interceptor moves in the exoatmosphere, and a moving target is considered.…”

Section: Generalized Required Velocitymentioning

confidence: 99%

“…At a fi rst glance, the concepts of the 2 guidance categories seem to be diff erent. Th e concepts of required velocity and velocity-to-be-gained can also be utilized or generalized for interception of moving targets (Jalali-Naini and Pourtakdoust 2005;Chen et al 2010). Th e velocity-to-be-gained vector becomes proportional to ZEM when the gravitational acceleration is assumed to be constant.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of Conceptual Midcourse Guidance Laws for Long-Range Exoatmospheric Interceptors

Mohammad-abadi

Jalali-Naini

2017

J.Aerosp. Technol. Manag.

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This paper presents a comprehensive study on the performance analysis of 8 conceptual guidance laws for exoatmospheric interception of ballistic missiles. The problem is to find the effective thrust direction of interceptor for interception of short-to-super range ballistic missiles. The zero-effort miss and the generalized required velocity concept are utilized for interception of moving targets. By comparison of the 8 conceptual guidance laws, the thrust direction is suggested to be in the direction of generalized velocity-to-begained, or constant velocity-to-be-gained direction, rather than to be in the direction along zero-effort miss, or that of linear optimal solution for long-to-super range interception. Even for short coasting ranges, the generalized velocity-to-be-gained may be utilized because of reasonable computational burden for required velocity rather than the numerical computation for zero-effort miss or linear optimal solution with the same miss distance error. In addition, the fuel consumption of the suggested direction has less sensitivity due to estimation error in intercept time. The guidance law based on constant velocity-to-be-gained direction and the optimal solution are suitable for satellites launch vehicles and space missions.

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Section: Generalized Required Velocitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Evaluation of Conceptual Midcourse Guidance Laws for Long-Range Exoatmospheric Interceptors

Mohammad-abadi

Jalali-Naini

2017

J.Aerosp. Technol. Manag.

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“…By the definition: Equation 66 the terminal commanded acceleration is obtained as ( t 0 =0): Equation 67 The commanded acceleration is usually expressed in the form of u =( N ′/ t go 2 ) ZEM where N ′ is the effective navigation ratio in comparison with True PN. Therefore: Equation 68 The effective navigation ratio can be roughly approximated by N ′= m +2+0.75 ct go for m p =0,0≤ m ≤3, c <0.1(1/ s ), and t go <30 s (Jalali‐Naini and Pourtakdoust, 2005b). It implies that the effective navigation ratio increases with increasing the drag deceleration and time‐to‐go.…”

Section: Prediction Of Velocity Profile and Effective Navigation Ratiomentioning

confidence: 99%

“…The effective navigation ratio for zero‐lag EGL when f ( t ) is proportional to t go m is given by ( m p =0, t c = t f ): Equation 96 where v p = v ( t p ). For m =1 and t < t p we obtain (Jalali‐Naini and Pourtakdoust, 2005c): Equation 97 where: Equation 98 and η = a x t pg / v .…”

Section: Prediction Of Velocity Profile and Effective Navigation Ratiomentioning

confidence: 99%

On the predicted errors of atmospheric guidance laws

Jalali-Naini

Pourtakdoust

2008

Aircraft Engineering and Aerospace Technology

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PurposeThe purpose of this paper is to develop a novel solution for the predicted error and introduces a systematic method to develop optimal and explicit guidance strategies for different missions.Design/methodology/approachThe predicted error is derived from its basic definition through analytical dynamics. The relations are developed for two classes of systems. First, for systems in which the acceleration commands are truncated at a specified time. Second, for systems in which the corrective maneuvers are cut off at a specified time. The predicted error differential equation is obtained in a way that allows for derivation of several optimal and explicit guidance schemes.FindingsThe effect of tangential acceleration in conjunction with autopilot dynamics can be realized in guidance gain and the predicted error. The differential equation of velocity‐to‐be‐gained is obtained assuming the gravitational acceleration to be given as a vectorial function of time. The relations for different velocity profiles are obtained and discussed including the effective navigation ratio.Research limitations/implicationsThe guidance/control system is modeled as a linear time‐varying dynamic and of arbitrary‐order. The gravitational acceleration is assumed as a given vectorial function of time.Practical implicationsThe presented schemes are applicable to both midcourse and terminal guidance laws with/without velocity constraints.Originality/valueProviding a new analytical solution of predicted errors with final position and velocity constraints and their differential equations considering the thrust/drag acceleration and autopilot dynamics in the presence of gravity.

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“…To the best of author's knowledge, an algorithm taking all of the above requirements into account is hardly found in the open literature. The guidance laws based on zero-effort-miss formulation and optimal control such as those presented in [3], [4], [8], [12]- [15] provide analytical expression for the lateral acceleration command which is desirable for implementation and verification. However, most of the midcourse guidance methods introduced above rely on an externally supplied PIP for their operation.…”

Section: Introductionmentioning

confidence: 99%