Satellite Attitude Determination Using Reaction Wheel Angular Sensors
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Solution Overview
Problem
Current satellite attitude determination systems relying on stellar sensors and gyrometers are costly and suffer from measurement noise, making it challenging to accurately determine satellite attitude and attitude variations without gyrometers.
Innovation Solution
A device and method using angular sensors to measure the rotation of inertial actuators, such as reaction wheels, to determine satellite attitude and attitude variations, combined with digital estimation filters like Kalman filters, to enhance accuracy and reduce noise, potentially eliminating the need for gyrometers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gyrometers are used to determine satellite attitude variations, then measurement accuracy is improved, but device cost and complexity increase
Solution Approach 1:
The patent combines stellar sensor measurements with reaction wheel angle measurements into a unified attitude determination system. The computation means processes both data sources together, using the reaction wheel angles to constrain and filter the stellar sensor measurements, thereby achieving gyrometer-level accuracy without requiring separate gyrometers.
Solution Approach 2:
The reaction wheels serve dual functions: they act as attitude control actuators to adjust satellite orientation, and simultaneously serve as attitude sensors through their angle measurement devices. This eliminates the need for dedicated gyrometers, reducing system complexity while maintaining measurement capability.
2Device complexity
If stellar sensors are used to determine satellite attitude, then device cost is reduced, but measurement noise increases
Solution Approach 1:
The computation means implements a feedback mechanism where reaction wheel angle measurements continuously constrain and filter stellar sensor measurements. The reaction wheel data provides a reference that corrects stellar sensor noise, ensuring accurate attitude determination while maintaining cost-effectiveness.
Solution Approach 2:
The reaction wheel angle measurements act as an intermediary that mediates between the noisy stellar sensor data and the final attitude determination. By processing both data sources through the computation means, the system filters stellar sensor noise without requiring expensive gyrometers.
3Device complexity
If reaction wheel angle measurements are used to determine satellite attitude, then gyrometers can be eliminated, but measurement noise from angular sensors increases
Solution Approach 1:
The patent merges reaction wheel angle measurements with stellar sensor measurements in the computation means. This combination allows the system to eliminate gyrometers while compensating for angular sensor noise through the complementary stellar sensor data, maintaining accurate attitude determination.
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 approach improves the accuracy of satellite attitude determination by using direct angle measurements from angular sensors, reducing noise and costs, while maintaining or improving performance compared to systems relying solely on stellar sensors or gyrometers.
Implementation Method 1
an angular sensor intended to equip the at least one inertial actuator, suitable for measuring the angle of rotation of the rotary element about its axis of rotation
Implementation Method 2
By virtue of the principle of conservation of the kinetic moment, the variations of the speed of rotation of the satellite and of the speed of rotation of the rotary element of the inertial actuator are linked.
Implementation Method 3
the computation means comprise at least one digital estimation filter, preferably a Kalman filter
Data Source
AI summary
A device for determining the attitude or variation in attitude of a satellite fitted with an attitude control system comprising at least one inertial actuator. The inertial actuator comprises a rotary element mounted to rotate about an axis of rotation. The rotation of the rotary element is controlled to generate a torque to control controlling the attitude of the satellite. The angular sensor of the device measures the angular rotation of the rotary element about its axis of rotation. The computation unit determines the attitude or variation in attitude of the satellite induced by the rotation of the rotary element as a function of the measurements of angular rotation of the rotary element by the angular sensor. A satellite carrying such a device and a method for determining the attitude or variation in attitude.