Spacecraft Relative Position Control Using Signal Power Comparison
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Solution Overview
Problem
Current methods for positioning spacecraft in formation, such as satellites, face challenges with accuracy and complexity due to the need for multiple antennas and ambiguity in signal path difference measurements, which complicates collision detection and reconfiguration.
Innovation Solution
A control device with at least three send/receive antennas on different faces of a spacecraft, using processor means to estimate signal directions and distances by comparing received signal powers to stored cartographic data, and incorporating features for signal-to-noise ratio measurements, time division schemes, and collision risk detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple antennas are installed on differently oriented faces of the spacecraft to enable control in all directions, then the ability to determine any relative positions is improved, but the device complexity and installation difficulty increase
Solution Approach 1:
The patent applies universality by making each antenna both a transmitter and a receiver, allowing it to perform multiple functions. The send/receive antennas are configured to transmit reference signals to other spacecraft and simultaneously receive signals from other spacecraft, eliminating the need for separate transmit and receive antenna systems for each direction.
Solution Approach 2:
The patent merges the transmit and receive functions into a single antenna system. Instead of having separate transmit and receive antennas, the invention combines these functions in unified send/receive antennas that operate in different time slots, reducing the total number of antennas required while maintaining full-directional capability.
2Measurement precision
If path difference measurements are used to determine send directions, then positioning accuracy can be achieved, but ambiguity in measurements complicates collision detection and reduces reaction time
Solution Approach 1:
The patent replaces the complex mechanical/computational process of resolving path difference ambiguities with a direct power comparison method. Instead of measuring path differences and performing complex calculations to resolve ambiguities, the invention directly compares signal powers from multiple antennas to determine send directions, significantly simplifying the computation and reducing reaction time.
Solution Approach 2:
The patent changes the measurement parameter from path difference to signal power. By measuring and comparing the power of received signals rather than calculating path differences, the system achieves accurate send direction determination without the ambiguity problems inherent in path difference measurements, enabling faster collision detection.
3Measurement precision
If robust methods are used to alleviate ambiguity in path difference measurements, then measurement accuracy is improved, but the complexity of the control device increases
Solution Approach 1:
The patent replaces complex ambiguity resolution algorithms with a straightforward power comparison approach. Instead of implementing sophisticated signal processing to resolve path difference ambiguities, the invention uses simple power measurements from multiple antennas to directly determine send directions, dramatically reducing computational complexity.
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 solution enhances the accuracy of relative position determination and collision risk assessment, simplifying the installation and operation of the control device while improving reaction time and reducing complexity.
Implementation Method 1
send/receive antennas, possibly complemented by receive antennas, installed on differently oriented faces of the spacecraft and responsible for sending/receiving radio-frequency (RF) signals
Implementation Method 2
first measuring means adapted to determine the power of the signals received by each of said antennas and to deliver sets of measurements of powers each associated with one of said other spacecraft of the group
Data Source
AI summary
A control device (D) for a spacecraft of a group of spacecraft intended to travel in a chosen formation comprises i) a set of at least three send/receive antennas (A1-A3) installed on at least three differently oriented faces of its spacecraft and adapted to send/receive radio-frequency signals, ii) first measuring means (M1) responsible for determining the power of the signals received by each of the antennas (A1-A3) and for delivering sets of powers each associated with one of the other spacecraft of the group, iii) storage means (BD) responsible for storing sets of cartographic data each representative of the normalized powers of the signals received by each of the antennas (A1-A3) as a function of chosen send directions, and iv) processor means (MT) responsible for comparing each set of powers delivered by the first measuring means (M1) to the stored sets of cartographic data in order to estimate each send direction of the signals sent by the other spacecraft of the group with respect to a system of axes fixed with respect to their spacecraft.