Guided Munition Roll Orientation from Lateral Turn Estimation
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Solution Overview
Problem
Existing methods for determining the roll orientation of a rocket or guided munition during flight are hindered by the need for the rocket to remain stationary, preventing it from engaging targets at short and intermediate ranges due to the unknown initial roll orientation and spinning rate.
Innovation Solution
A processor-implemented method that calculates a ratio of lateral acceleration to velocity to generate an estimated lateral turn rate vector, integrating it over time to predict attitude changes, while also measuring and integrating lateral turn rate vectors to determine a gravity direction vector, allowing continuous orientation estimation and maneuverability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing methods are used to estimate rocket roll orientation, then orientation estimation can be performed, but the rocket cannot perform maneuvers during data collection
Solution Approach 1:
The patent transforms the static measurement process into a dynamic one by incorporating rocket maneuvers into the orientation estimation algorithm. The system continuously updates roll orientation estimates while the rocket performs maneuvers, using accelerometer and GPS data captured during these dynamic conditions. This resolves the contradiction by making the measurement process adaptive to rather than restrictive of rocket maneuvers.
Solution Approach 2:
The patent changes the parameters used for orientation estimation from static, maneuver-free conditions to dynamic conditions that include maneuvers. By incorporating maneuver detection and compensation into the estimation algorithm, the system can accurately determine roll orientation even when the rocket is actively maneuvering, thus eliminating the restriction on ease of operation.
2Measurement precision
If the rocket remains stationary for orientation estimation, then accurate roll orientation can be determined, but target engagement at short and intermediate ranges is prevented
Solution Approach 1:
The patent enables continuous orientation estimation throughout the entire flight profile, including during target engagement maneuvers. Rather than requiring a separate, stationary estimation phase that delays target engagement, the system continuously updates roll orientation using data from accelerometers and GPS receivers throughout flight, maintaining measurement precision while enabling uninterrupted productivity.
Solution Approach 2:
The patent performs preliminary calibration and algorithm setup during manufacturing or pre-flight, so that during actual flight the system can immediately begin continuous orientation estimation without requiring stationary periods. This preliminary preparation enables the rocket to engage targets at any range without delay while maintaining accurate roll orientation determination.
3Measurement precision
If traditional orientation estimation methods are used, then roll orientation can be estimated, but the process takes 5 to 10 seconds which delays target engagement
Solution Approach 1:
The patent implements periodic updates of roll orientation estimates using continuously collected accelerometer and GPS data throughout flight. Rather than requiring a single, lengthy 5-10 second stationary measurement period, the system performs rapid, periodic estimation updates at multiple time points during flight, reducing the effective time to obtain accurate orientation data and enabling faster target engagement.
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
Enables continuous and accurate determination of rocket orientation during flight, allowing engagement of targets without restrictions on maneuverability, using low-cost components like accelerometers and turn rate sensors, and providing updated estimates for improved guidance and control.
Implementation Method 1
an accelerometer configured to measure a lateral acceleration vector of the guided munition
Implementation Method 2
a lateral turn rate sensor configured to measure a lateral turn rate vector of the guided munition
Implementation Method 3
calculating a ratio of a lateral acceleration vector measurement of the guided munition to a velocity of the guided munition, to generate an estimated lateral turn rate vector
Implementation Method 4
integrating the estimated lateral turn rate vector, over a period of time associated with flight of the guided munition, to generate a first type of predicted attitude change
Implementation Method 5
calculating a gravity direction vector based on a difference between the first type of predicted attitude change and the second type of predicted attitude change
Data Source
AI summary
Techniques are provided for determination of a guided-munition orientation during flight based on lateral acceleration, velocity, and turn rate of the guided-munition. A methodology implementing the techniques, according to an embodiment, includes obtaining a lateral acceleration vector measurement and a velocity of the guided-munition, and calculating a ratio of the two, to generate an estimated lateral turn vector of the guided-munition. The method also includes integrating the estimated lateral turn vector, over a period of time associated with flight of the guided-munition, to generate a first type of predicted attitude change. The method further includes obtaining and integrating a lateral turn rate vector measurement of the guided-munition, over the period of time associated with flight of the guided-munition, to generate a second type of predicted attitude change. The method further includes calculating a gravity direction vector based on a difference between the first and second types of predicted attitude change.