Tape Spring Deployment Mechanism for Satellite Structures
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Solution Overview
Problem
Existing deployable structures in space, such as solar generators, face challenges with large surface mass and inertia, and instability during deployment due to the inherent properties of conventional tape measures, which can lead to uncontrolled unfolding and instability in the deployed state.
Innovation Solution
A device for deploying and retracting a flexible structure using a tape measure with a deployment and unfolding axis, where the tape measure is mounted folded in a U-shape with two branches, and a rotor allows autonomous unwinding, incorporating a regulating device for controlled deployment and refolding, and optional additional features like rollers and flexible membranes for enhanced stability and rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If conventional tape measures are used for deployment, then autonomous deployment is achieved, but uncontrolled unfolding and instability occur
Solution Approach 1:
The patent applies dynamics by making the tape measure's stiffness variable through curvature. The tape measure transitions from a flexible coiled state during storage to a rigid extended state during deployment, with the convex face providing increasing stiffness as it unrolls. This dynamic stiffness change enables controlled autonomous deployment without violent unrolling.
Solution Approach 2:
The patent changes the physical parameter of stiffness by utilizing the inherent curvature of the tape measure. The convex face of the tape measure has naturally higher stiffness due to its curved geometry, and this stiffness parameter increases as the tape unrolls from a coiled to an extended state, providing progressive control during deployment.
2Weight of moving object
If flexible structures are used to reduce storage volume, then mass and inertia are reduced, but stability in deployed state deteriorates
Solution Approach 1:
The patent applies local quality by making different faces of the tape measure have different stiffness properties. The convex face is inherently stiffer due to its curved geometry, while the concave face remains more flexible. This local differentiation in stiffness provides stability on the convex side while maintaining flexibility for rolling during deployment and retraction.
Solution Approach 2:
The patent utilizes curvature as a structural feature to provide stiffness. The tape measure has a convex curved face that naturally resists bending, providing stability when deployed. The curved geometry allows the tape to maintain its shape and resist orbital forces without requiring additional rigid support structures.
3Stability of the object's composition
If additional holding devices are used to maintain stability, then deployed state stability is improved, but device complexity increases
Solution Approach 1:
The patent applies self-service by designing the tape measure to provide its own stability through the inherent stiffness of its convex face. The structure serves itself by using the geometric properties of the curved tape to resist bending and maintain stability during deployment, eliminating the need for separate holding devices or stabilization mechanisms.
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
The solution provides a compact, stable, and controlled deployment mechanism that optimizes storage volume, ensures autonomous and progressive deployment, and maintains structural stability without the need for additional holding devices, addressing the issues of mass, inertia, and instability in existing systems.
Implementation Method 1
measuring tapes are known in the space field as being flexible tapes having an arcuate section whose radius of curvature is convex on a first side and concave on a second side, these tapes being able to pass from coiled state in the unrolled state essentially thanks to their own elastic energy
Data Source
Figure 1a~1d
Figure 2a~2c
Figure 3a~3f
AI summary
The device has a tape spring (10) including an axis of unfurling and refurling parallel to a device first axis and a rotor rotated about a second axis perpendicular to the former axis. The tape spring is autonomously passed from a state in which the spring is wound around the rotor to an unwound state. The spring is mounted bent in two in a shape of U with two branches (11, 12), and includes two ends (17) of the two branches fixed rigidly to respective anchor points (6), where one of the ends of respective branch of the spring is mounted between two jaws of the respective anchor point. The tape spring is made of a corrugated sheet. An independent claim is also included for a flexible unfurlable structure.