Compound Steering Law for Low Thrust Orbit Transfer

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Solution Overview

Problem

Existing low-thrust transfer orbit mission strategies require multiple phases and frequent switching between steering laws to achieve both orbit eccentricity and semi-major axis targets, leading to long mission durations and operational complexities due to discontinuous thruster firing and abrupt spacecraft orientation changes.

Innovation Solution

A compound steering law that calculates and applies a vector sum of velocity changes to simultaneously adjust orbit eccentricity and semi-major axis, allowing continuous thruster firing and smooth orientation transitions, thereby reducing total transfer orbit mission duration and increasing payload capacity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If multiple phases and frequent switching between steering laws are used to achieve orbit eccentricity and semi-major axis targets, then the spacecraft can reach the desired orbit parameters, but the mission duration increases and operational complexity increases due to discontinuous thruster firing and abrupt orientation changes

Engineering Contradiction:

Improveorbit parameter accuracyVSAvoidmission duration

Core Design Contradiction:

Manufacturing precisionVSDuration of action of moving object

Solution Approach 1:

The patent combines multiple steering laws (Hohmann transfer steering law for semi-major axis and bi-elliptic transfer steering law for eccentricity) into a single compound steering law. This allows simultaneous achievement of both orbit parameters in one continuous maneuver rather than requiring separate phases, thereby reducing mission duration while maintaining accuracy

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The compound steering law enables continuous thruster firing throughout the entire transfer orbit mission. By calculating the vector sum of velocity changes continuously and applying thrust in the resulting direction, the system eliminates discontinuous firing patterns and abrupt orientation changes, reducing operational complexity and mission duration

Inventive Principle:

Principle #20Continuity of useful action

2Manufacturing precision

If multiple phases and frequent switching between steering laws are used to achieve orbit eccentricity and semi-major axis targets, then the spacecraft can reach the desired orbit parameters, but operational complexity increases due to discontinuous thruster firing and abrupt spacecraft orientation changes

Engineering Contradiction:

Improveorbit parameter accuracyVSAvoidoperational complexity

Core Design Contradiction:

Manufacturing precisionVSEase of operation

Solution Approach 1:

The patent merges multiple discrete steering law phases into a single unified compound steering law. This consolidation eliminates the need for frequent switching between different steering laws, reducing operational complexity while maintaining the ability to achieve precise orbit parameters

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The compound steering law provides continuous guidance throughout the transfer mission, eliminating discontinuous thruster firing and abrupt orientation changes. The continuous calculation and application of the vector sum of velocity changes simplifies operational procedures and reduces complexity

Inventive Principle:

Principle #20Continuity of useful action

3Adaptability or versatility

If traditional separate-phase approach is used to adjust orbit parameters, then each parameter can be controlled independently, but the total mission duration increases and payload capacity decreases

Engineering Contradiction:

Improveparameter control independenceVSAvoidpayload capacity

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The patent combines the control of orbit eccentricity and semi-major axis into a single compound steering maneuver. By calculating the vector sum of velocity changes for both parameters simultaneously and applying thrust in the resulting direction, the system achieves both parameter adjustments in one continuous phase, reducing total mission duration and increasing payload capacity while maintaining adaptability

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS8457810B1Compound steering law for efficient low thrust transfer orbit trajectory

Publication Date: 2013.06.04 THE BOEING CO

AI summary

A method and system for application of a compound steering law for efficient low thrust transfer orbit trajectory for a spacecraft are disclosed. The method involves calculating, with at least one processor, a desired orbit for the spacecraft. The method further involves calculating a velocity change required to achieve an orbit eccentricity and a velocity change required to achieve a semi-major axis, both of which correspond to the desired orbit for the spacecraft. Also, the method involves calculating the direction of the vector sum of the velocity change required to achieve the orbit eccentricity and the velocity change required to achieve the semi-major axis. Further, the method involves firing at least one thruster of the spacecraft in the direction of the vector sum in order to change the current orbit of the spacecraft to the desired orbit for the spacecraft, thereby changing the orbit eccentricity and the semi-major axis simultaneously.