Ballistic Guidance System Using Dynamic Canard Steering
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Solution Overview
Problem
Ballistic projectiles face limitations in maneuverability due to size restrictions of control surfaces, leading to reduced range and accuracy, with complex relationships between impact location changes and control actions, exacerbated by Magnus forces and spin effects.
Innovation Solution
A guidance control system that adjusts roll and lift canards based on predicted impact error estimates and remaining maneuverability, using steering maps to generate roll and lift commands, allowing for periodic updates during flight to correct the projectile's path and increase operational range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If control surfaces are increased in size to improve maneuverability, then the projectile can achieve greater maneuverability, but the projectile size and weight increase, reducing range
Solution Approach 1:
The patent employs dynamic control surfaces (canards) that can actively adjust their deflection angles during flight to optimize maneuverability. The control surfaces are sized appropriately for stability, yet through dynamic deflection control, they achieve the necessary maneuver envelope without requiring oversized static surfaces.
Solution Approach 2:
The guidance system changes flight parameters (angle of attack, roll rate, canard deflection) to achieve maneuverability within the constraints of fixed control surface sizes. By dynamically adjusting these parameters, the system maximizes the effective maneuver envelope without increasing physical dimensions.
2Adaptability or versatility
If control surfaces are deflected to increase maneuverability, then steering capability improves, but aerodynamic drag increases, reducing range
Solution Approach 1:
The guidance system applies partial canard deflections rather than maximum deflections, using only the amount of steering input necessary to correct trajectory errors. This minimizes drag penalties while achieving the required steering capability to reach the target.
Solution Approach 2:
The system continuously monitors actual trajectory versus desired trajectory and adjusts canard deflections in real-time based on feedback from impact point predictions. This ensures that control surfaces are deflected only as much as necessary to correct errors, minimizing energy loss to drag.
3Manufacturing precision
If complex control actions are taken to adjust impact location, then targeting accuracy improves, but the complexity of the control process increases
Solution Approach 1:
The system performs preliminary calculations of impact point predictions and required control actions during flight. By pre-computing the necessary canard deflections based on current trajectory and remaining flight time, the system simplifies the real-time control decision-making process while maintaining high targeting accuracy.
Solution Approach 2:
The guidance system uses feedback from impact point predictions to continuously adjust control actions. This closed-loop approach breaks down the complex control problem into manageable iterative corrections, where each control action is based on the latest trajectory assessment, simplifying the overall control process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances targeting accuracy, increases the effective maneuver envelope, and conserves energy by optimizing steering commands, thereby improving the projectile's ability to correct for miss errors and environmental disturbances.
Implementation Method 1
The control process is challenging, as there is a complex relationship between any changes in impact location and the control actions that must be taken to determine the optimal steering commands. This complexity arises mainly from ballistic geometry, Magnus forces and moments, and drag caused by the canard deflections.
Implementation Method 2
Ballistic projectiles are typically limited in their maneuverability as they lack self-propulsion and rely on adjustments to flight control surfaces that provide a limited maneuver at the expense of reduced range. This limit is due, at least in part, to a size restriction of the control surfaces imposed by fight stability, a loss of range caused by steering, and the effects of projectile spin and Magnus force.
Data Source
AI summary
Techniques are provided for guiding a projectile. A methodology implementing the techniques according to an embodiment includes generating a roll command based on a roll angle obtained from a steering map that causes a change in range and cross range of the projectile that results in a ground motion closest to a desired ground motion. The method also includes calculating a remaining maximum maneuver distance for the projectile, over a time period extending from the current time of flight to the end of flight. The calculation is based on integration a series of maximum maneuvers, obtained from the steering map, at time intervals within the time period. The method further includes generating a lift command for the projectile based on: distance between the target location and an impact point prediction (IPP) calculated at the current time of flight; an error estimate of the IPP; and the remaining maximum maneuver distance.