Gimbaled Electric Thrusters for Spacecraft Spin Axis Reorientation
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Solution Overview
Problem
Maintaining attitude control in spacecraft during transfer orbits is challenging due to high disturbance torques, especially when passing through low perigees, making it difficult to raise satellites to higher orbits efficiently.
Innovation Solution
Spinning the spacecraft in a transfer orbit using electric thrusters with two-axis gimbal assemblies to adjust the spin axis, allowing for controlled velocity changes and attitude stabilization, with the controller determining gimbal angles to align and realign the spin axis to maximize solar panel exposure and achieve orbital raises.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If three-axis attitude control is performed in transfer orbit, then the satellite can maintain precise orientation, but high disturbance torques make it difficult to maintain control when passing through low perigees
Solution Approach 1:
The patent inverts the conventional approach by spinning the spacecraft body to achieve gyroscopic stability, then using gimbaled thrusters to control the spin axis orientation rather than controlling individual axis attitudes. This reversal transforms the control problem from actively counteracting disturbances to passively maintaining stability through rotation.
Solution Approach 2:
The patent changes the operational parameters by introducing continuous rotation speed as a control parameter. By adjusting the spin rate and thruster firing sequences, the system achieves attitude control through parameter modulation rather than traditional torque application, improving reliability in high-disturbance environments.
2Loss of energy
If electric thrusters are used to raise the orbit, then fuel consumption is reduced, but the thrusters must also provide attitude control which complicates the system
Solution Approach 1:
The patent makes the electric thrusters universal by enabling them to perform both orbital raising and attitude control functions. The gimbaled thrusters can be oriented to produce torque for spin axis control while simultaneously providing the delta-V needed for orbit raising, eliminating the need for separate attitude control thrusters.
Solution Approach 2:
The patent merges the attitude control function with the orbital maneuvering function by integrating gimbal mechanisms into the electric thruster assemblies. This combination allows a single thruster system to handle both rotational and translational control requirements, reducing overall system complexity despite the added gimbal degrees of freedom.
3Device complexity
If the spacecraft spins to achieve gyroscopic rigidity, then attitude control is simplified, but the spin axis must be precisely controlled to maximize solar panel exposure
Solution Approach 1:
The patent implements feedback control by continuously monitoring the spin axis orientation relative to the Sun and adjusting thruster firing sequences accordingly. The controller processes sensor data about actual spin axis position and modifies gimbal angles and thruster timing to maximize solar panel exposure while maintaining gyroscopic stability.
Solution Approach 2:
The patent employs dynamic control strategies by adjusting thruster firing sequences and gimbal angles in real-time based on the spacecraft's rotational state. Rather than static positioning, the system dynamically adapts the spin axis orientation to optimize solar exposure while maintaining the benefits of gyroscopic rigidity.
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 spinning spacecraft achieves gyroscopic rigidity and stable attitude control, enabling efficient orbital raises and minimizing the complexity of three-axis attitude control, thereby facilitating the transition to higher orbits like geosynchronous orbits.
Implementation Method 1
low-thrust electric thrusters produce a velocity change (ΔV) in the spacecraft to raise the orbit of the spacecraft
Implementation Method 2
Spinning a spacecraft (e.g., a satellite) in a transfer orbit mitigates issues of attitude control by providing gyroscopic rigidity
Implementation Method 3
the at least one of the electric thrusters is directed at the determined gimbal angles to produce a torque that adjusts the actual spin axis toward the target spin axis
Data Source
AI summary
Apparatus and methods for controlling a spacecraft for a transfer orbit. The spacecraft includes a propulsion subsystem with electric thrusters that are installed with two-axis gimbal assemblies. The spacecraft also includes a controller that identifies a target spin axis for the spacecraft, determines an actual spin axis for the spacecraft during the transfer orbit, determines gimbal angles for the electric thruster(s) that adjust the actual spin axis toward the target spin axis, and initiates a burn of the electric thruster(s) at the gimbal angles.