Antenna Pointing System With Parallel Actuators
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Solution Overview
Problem
Existing steerable antenna systems for spacecraft are hindered by high profile, heavy mass, structural inefficiency, high cost, low accuracy, low reliability, and reduced RF performance, particularly when requiring small scan angles.
Innovation Solution
The implementation of a flexible mounting structure using universal joints with bearings and flexures, combined with two rotary actuators positioned at 90 degrees relative to the rotation center, allows for improved angular displacement and eliminates the need for hold-down mechanisms and moving harnesses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If two rotary actuators are assembled in a sequential chain with hold-down and release mechanisms, then the antenna can be steered over a scan angle, but the system has high profile, heavy mass, and high device complexity
Solution Approach 1:
The patent removes the hold-down and release mechanisms (HRM) from the sequential chain actuator system. By extracting these complex components, the invention achieves a simpler structure that eliminates the need for fixed predetermined stowed positions while maintaining the ability to steer the antenna over required scan angles.
Solution Approach 2:
Instead of using a sequential chain where actuators are connected in series requiring HRM, the patent inverts the approach by using two rotary actuators connected in parallel to a common payload. This inversion eliminates the need for hold-down mechanisms and allows flexible stowed position selection.
2Stability of the object's composition
If sequential chain actuators with HRM are used, then the antenna can be held in fixed positions, but the system requires fixed predetermined stowed position for launch and has low reliability
Solution Approach 1:
The patent transitions from a static system requiring fixed predetermined stowed positions to a dynamic system where the payload can be stowed at any position. The two parallel rotary actuators can independently position the payload, providing flexibility and eliminating the reliability issues associated with HRM mechanisms.
3Adaptability or versatility
If sequential chain actuators are used, then the antenna can be steered, but the system has high mass and reduced RF performance
Solution Approach 1:
By removing the HRM components from the sequential chain design, the patent eliminates unnecessary mass. The parallel actuator configuration with direct mounting to the payload reduces the overall mass of the pointing device while maintaining full antenna steering capability.
4Ease of operation
If sequential chain actuators with HRM are used, then the antenna can be positioned accurately, but the system has low accuracy and low resolution
Solution Approach 1:
The patent inverts the actuator configuration from sequential chain to parallel connection. This inversion, combined with eliminating HRM, allows for more precise control of the payload position and orientation, improving pointing accuracy and resolution while maintaining ease of operation.
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 results in a lower profile, lower mass, higher accuracy, and improved RF performance, reducing costs and enhancing reliability while enabling last-minute stowed position selection and eliminating the need for RF rotary joints and electrical wiring.
Implementation Method 1
two rotary actuators (RA) with cranks (22) and connecting rods (24) to impart rotations to a payload structure (26), such as an antenna reflector assembly
Implementation Method 2
The flexible mounting structure is a universal joint, including bearings, flexures or the like, preferably located near a geometric center of the payload
Data Source
Figure 1a~1b
Figure 2
Figure 3
AI summary
An antenna pointing system (10) for selectively moving a payload (26) relative to a mounting surface (14) includes at least one rotary actuator (20) having a moving part (22) movable relative to a fixed part mounted on the surface (14). A connecting rod (24) movably connects to the moving part (22) and to the payload (26). A flexible mounting structure (28) movably attaches the payload (26) to the mounting surface (14).