Reactionless Two-Axis Gimbal Scanning System
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Solution Overview
Problem
Existing suspension systems for optical scanning mirrors struggle to provide precise control over multiple axes while minimizing translational movement and maintaining reactionless operation, which is essential for applications like spacecraft scanning systems, where complexity and power requirements are a concern.
Innovation Solution
A two-axis suspension system with a mirror gimbal and a reaction mass gimbal, connected by a drive assembly with flexures that allow equal and opposite movements between the mirror and reaction mass, enabling rotation about two perpendicular axes without requiring additional actuators, thus minimizing mass and power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single degree of freedom reactionless system is used, then reactionless operation is achieved, but scanning capability is limited to one axis
Solution Approach 1:
The system divides the scanning function into two independent degrees of freedom, each handled by separate gimbal mechanisms (mirror gimbal and reaction mass gimbal) that can operate independently along different axes, enabling multi-axis scanning while maintaining reactionless operation
Solution Approach 2:
The reaction mass serves multiple functions: it provides reactionless operation through its equal and opposite movement, enables scanning about two perpendicular axes, and works with the flexure drive assembly to control the mirror's orientation without requiring separate actuators for each function
2Measurement precision
If actuators are added for both mirror and reaction mass, then control precision is improved, but mass and power requirements increase
Solution Approach 1:
The reaction mass system is self-actuating through the flexure drive assembly, which uses the reaction mass's own movement to generate equal and opposite motion of the mirror. The coils and magnets interact to produce the necessary rotational force without requiring external actuators on either the mirror or reaction mass, achieving precise control while minimizing mass
Solution Approach 2:
The drive assembly merges the control functions for both the mirror and reaction mass into a single integrated mechanism. The flexures connect the mirror and reaction mass such that their movements are coupled, allowing one actuator system to control both components simultaneously, reducing the total number of actuators needed
3Measurement precision
If multiple actuators are used for multi-axis control, then scanning accuracy is improved, but power requirements increase
Solution Approach 1:
The system uses the reaction mass's inertia and the flexure's elastic properties to store and transfer energy, reducing the continuous power requirement. The coils only need to provide transient electromagnetic forces to initiate movement, after which the system's mechanical energy carries the scanning operation, significantly reducing average power consumption
Solution Approach 2:
The scanning operation utilizes periodic oscillation of the reaction mass about its center of gravity, where the flexure assembly stores energy during part of the cycle and releases it during other parts, reducing the continuous power input needed compared to direct actuation of both axes independently
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 configuration allows for high scanning accuracy and rapid scan rates about multiple axes while maintaining reactionless operation, reducing complexity and power requirements, and is suitable for applications where minimal perturbation is necessary, such as in spacecraft.
Implementation Method 1
A set of coils mounted to a base interact with a number of magnets that are fixed to the reaction mass, enabling an angle of the reaction mass about one or both of the X'' and Y'' axes to be selectively changed
Implementation Method 2
The drive assembly includes a first flexure or set of flexures that transfers a rotation of the reaction mass about the X'' axis to an equal but opposite rotation of the mirror about the X' axis
Data Source
AI summary
Suspension system structures and methods are provided. A system as disclosed includes a supported object that is mounted to a post by a first two axis gimbal. The system also includes a reaction mass that is mounted to the post by a second two axis gimbal. The supported object and the reaction mass are connected to one another by a drive assembly. The drive assembly transfers a rotation of the reaction mass about either of the two axes in a first direction to a rotation of the supported object about a parallel axis in an opposite direction.