Satellite Attitude Control Using Burst Torque Electric Motors
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Solution Overview
Problem
Current satellite attitude control systems face challenges in executing agile attitude change maneuvers due to high torque requirements, which can lead to vibrations and energy inefficiencies, especially when using tethered gyroscopes or engines, affecting the quality of high-resolution optical data and satellite orientation stability.
Innovation Solution
An attitude control apparatus comprising at least three electric motors, with a controller that operates them only when acceleration and braking torques are required, generating torques for any orientation and minimizing continuous operation to prevent vibrations and conserve energy, while also allowing for redundancy and energy recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If tethered gyroscopes (CMG) are used to generate high torque for agile attitude change maneuvers, then the torque capability is improved, but vibrations are generated and motion blurring occurs in sensor data
Solution Approach 1:
The patent extracts the harmful vibrations from the system by using reaction wheels instead of CMGs. The reaction wheels generate torque through controlled acceleration and deceleration without the continuous high-speed rotation that causes vibrations in CMGs, thereby eliminating the source of motion blurring in sensor data while maintaining the required torque capability for agile maneuvers.
Solution Approach 2:
The patent employs electric motors with finite energy storage that are operated in short bursts for acceleration and braking torques. Instead of continuously operating CMGs that generate constant vibrations, the system uses temporarily energized motors that deliver high torque only when needed, then return to a non-operational state, effectively using short-lived torque bursts to achieve maneuvering goals without sustained harmful vibrations.
2Force
If tethered gyroscopes (CMG) are used to execute agile attitude change maneuvers, then the torque capability is improved, but energy losses due to friction must be continuously compensated
Solution Approach 1:
The patent implements periodic action by operating electric motors only during specific phases of the maneuver (acceleration and braking torques) rather than continuous operation. The motors are energized in controlled pulses to achieve the required torque changes, then deactivated. This periodic operation eliminates continuous friction losses associated with CMGs while still achieving the necessary attitude changes through strategically timed torque applications.
3Force
If engines are used to generate torque for attitude change maneuvers, then the torque capability is improved, but the satellite center of gravity and moments of inertia change due to fuel consumption
Solution Approach 1:
The patent replaces the chemical propulsion system (engines consuming fuel) with an electrical propulsion system (reaction wheels using stored energy). This substitution eliminates the mass loss associated with fuel consumption, thereby maintaining constant center of gravity and moments of inertia throughout the maneuver. The electric motors provide the necessary torque through electromagnetic forces without the harmful side effect of changing the satellite's mass distribution.
4Stability of the object's composition
If electric motors are operated continuously to maintain satellite orientation, then the orientation stability is improved, but energy consumption increases
Solution Approach 1:
The patent applies periodic action by operating electric motors only during specific maneuver phases (acceleration and braking) rather than continuous operation. The motors are activated temporarily to change the satellite's orientation, then deactivated to maintain the new orientation passively. This approach achieves orientation stability through strategic intermittent control rather than continuous energy consumption, significantly reducing overall power usage while maintaining maneuvering capability.
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 enables efficient and vibration-free agile attitude changes, reduces energy consumption, and enhances satellite resilience by using electric motors strategically, allowing for precise control and flexible adaptation to different satellite configurations.
Implementation Method 1
The satellite comprises an attitude control apparatus with at least three electric motors... generating torques for any orientation
Implementation Method 2
calculating an acceleration torque and a braking torque based on a comparison between the received target orientation and an actual orientation of the satellite... generating the calculated acceleration torque and the calculated braking torque
Data Source
AI summary
An attitude control apparatus for a satellite includes: at least three electric motors, wherein the at least three electric motors are arranged in such a way that a torque may be generated with any orientation of an associated torque vector, and a controller, wherein the controller is configured to drive the at least three electric motors based on a torque controller. The torque controller is adapted to operate the at least three electric motors outside a rest state only when an acceleration torque and a braking torque are required to execute an agile attitude change maneuver. There is also described an associated method.