Missile Guidance Using Higher Order Sliding Mode Control
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Solution Overview
Problem
Current missile guidance and control systems face challenges in intercepting maneuvering targets due to assumptions like zero target acceleration and perfect interceptor dynamics, leading to inaccuracies and the need for complex modeling, especially in hypersonic conditions where aerodynamic interactions and unpredictable dynamics prevail.
Innovation Solution
The implementation of Higher Order Sliding Mode (HOSM) control techniques for missile guidance, allowing concurrent use of multiple divert mechanisms like thrust, aerodynamic lift, and thrusters, without relying on detailed dynamic models, and enabling robustness against disturbances and model uncertainties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional Proportional Navigation (PN) guidance is used, then the guidance system is simple to implement, but it assumes zero target acceleration and perfect interceptor dynamics which leads to inaccuracy against maneuvering targets
Solution Approach 1:
The patent transforms the guidance approach by changing from model-based parameter estimation to disturbance-based compensation. Instead of estimating target acceleration and interceptor dynamics parameters (which requires complex modeling), the system treats all modeling errors and external disturbances as a single bounded disturbance term that is compensated through sliding mode control. This parameter transformation resolves the contradiction by achieving high accuracy without requiring complex dynamic models.
Solution Approach 2:
The patent introduces a sliding mode observer as an intermediary element that estimates the total disturbance (including target maneuver and modeling errors) without requiring separate estimation of each component. This intermediary disturbance observer enables accurate guidance against maneuvering targets while avoiding the complexity of detailed dynamic modeling and multiple separate estimators.
2Reliability
If complex dynamic models and multiple estimators are used to account for hypersonic aerodynamic interactions, then guidance accuracy improves, but system complexity and computational burden increase significantly
Solution Approach 1:
The patent merges multiple separate estimation functions (target acceleration estimation, aerodynamic parameter estimation, disturbance estimation) into a single sliding mode observer that estimates the total equivalent disturbance. This consolidation achieves the same robustness against hypersonic aerodynamic interactions and target maneuvers while dramatically reducing modeling complexity and computational burden by treating all uncertainties as a unified bounded disturbance.
Solution Approach 2:
The patent extracts the complex dynamic modeling requirements by separating the known control inputs from the unknown disturbances. Instead of modeling every aspect of hypersonic aerodynamics and interceptor dynamics, the system extracts only the essential control command and treats all other effects (aerodynamic interactions, modeling errors, external disturbances) as a single disturbance term to be compensated, thereby reducing modeling complexity while maintaining reliability.
3Ease of manufacture
If conventional autopilot design based on internal mathematical models is used, then the control system is easier to design, but accuracy degrades when models become expensive and difficult to develop for larger domains
Solution Approach 1:
The patent enables the control system to self-adjust to unknown disturbances without relying on pre-developed complex mathematical models. The sliding mode observer continuously estimates the total disturbance in real-time, and the guidance law automatically compensates for it, allowing the system to maintain high accuracy across expanding operational domains without requiring increasingly complex and expensive model development and validation.
Data Source
AI summary
Higher Order Sliding Mode (HOSM) control techniques are applied to the Guidance Control (G&C) of interceptor missile in which velocity may be steered by combination of main thrust, aerodynamic lift and lateral on-off divert thrusters, and attitude may be steered by continuous or on-off actuators. Methods include the pointing of the seeker, its associated estimation processes, a guidance law that uses concurrent divert mechanisms, and an attitude autopilot. The insensitivity of the controller to matched disturbances allows the concurrent usage of the divert mechanisms without adverse effect on the accuracy. The controller also allows the de-coupling of the control of roll, pitch and yaw channels, and usage quaternions to represent body attitude and it provides control perfect robustness. While it conceivable to design separately the components of the G&C method, it is widely accepted that designing them in an integrated fashion usually produces a better result.