Feed Forward Command Aiding Architecture for Beam Steering

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Solution Overview

Problem

Current stabilization systems for optical and beam director systems face challenges in maintaining a stable optical axis, particularly at high magnification, leading to image degradation and beam motion, which are not adequately addressed by existing two-axis gimbal designs with limited frequency response in coarse stabilization.

Innovation Solution

A feed forward command aiding architecture is implemented, using a nested position and rate loop control system with frequency domain shaping, where angle and rate commands are generated from inertial data to stabilize the beam steering element, effectively reducing residual inertial pointing errors and enhancing disturbance rejection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a two-axis gimbal with beam steering element is used for stabilization, then device complexity and weight are reduced, but disturbance rejection performance is limited to a narrow frequency region

Engineering Contradiction:
Improvegimbal design complexityVSAvoiddisturbance rejection performance
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The control system is segmented into two independent but coordinated loops: an outer position loop and an inner rate loop. Each loop handles specific aspects of stabilization, with the position loop managing overall positioning and the rate loop handling velocity compensation. This segmentation allows the simplified two-axis gimbal to achieve performance comparable to complex multi-axis systems by dividing the control function across specialized sub-systems.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The feedforward command aiding architecture pre-computes and applies compensation commands based on anticipated disturbances before they fully affect the system. By using inertial rate feedback to generate coarse stabilization commands in advance, the system proactively counteracts disturbances rather than merely reacting to them, extending the effective frequency range of the simplified gimbal design.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If higher magnification is used to meet design requirements, then imaging resolution is improved, but optical axis stabilization performance requirements increase proportionally

Engineering Contradiction:
Improveimaging resolutionVSAvoidoptical axis stabilization
Core Design Contradiction:
Measurement precisionVSStability of the object's composition

Solution Approach 1:

The system employs dual feedback mechanisms: inertial rate feedback provides coarse stabilization by measuring and compensating for angular velocity changes, while electro-optic sensor feedback provides fine stabilization by measuring actual line-of-sight deviations. This layered feedback approach enables high magnification imaging by maintaining optical axis stability through multiple correction stages, allowing the system to achieve both high resolution and stable imaging.

Inventive Principle:
Principle #23Feedback

3Ease of manufacture

If conventional beam steering control methodology is used, then system implementation is straightforward, but stabilization error is reduced by only one order of magnitude over a limited frequency region

Engineering Contradiction:
Improvecontrol system implementationVSAvoidstabilization accuracy
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent transitions from conventional single-loop position control to a two-dimensional control space by adding the rate loop dimension. The nested rate loop operates independently within the position loop framework, creating a hierarchical control structure that addresses both position and velocity domains. This dimensional expansion enables the system to achieve an order of magnitude improvement in stabilization accuracy while maintaining implementation feasibility through modular control architecture.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 achieves significant improvement in disturbance rejection, reducing image imperfections and enabling the use of electro-optic sensors on vehicles with excessive base motion disturbance, providing clearer and steadier images by minimizing position loop errors and increasing the tolerance to base motion levels.

Implementation Method 1

a beam steering element of reflective design including a two-axis fast steering mirror

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP2826235B1Beam steering element feed forward command aiding architecture
Publication Date: 2019.04.24 RAYTHEON CO
  • EP2826235B1 patent drawingFigure 1
  • EP2826235B1 patent drawingFigure 2~3
  • EP2826235B1 patent drawingFigure 4~5

AI summary

A feed forward command aiding architecture with corresponding method, system, and computer product are provided. The feed forward command aiding architecture includes generating angle and rate commands from a received inertial data input. The angle command is feed into a proper order position loop producing an intermediate result. An angle feedback is differentiated producing a rate loop feedback. The intermediate result, rate command, and rate loop feedback are then feed into a proper order rate loop producing a torque command. The proper order rate loop is nested inside of the proper order position loop. The torque command being generated moves a beam steering element of an electro-optic sensor to deflect a line of sight of the electro-optic sensor by an angle approximating the received inertial angular input.