Proportional Derivative Matrix Control for Asymmetric Thrusters
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Solution Overview
Problem
Existing flight vehicle divert and attitude control systems face challenges in accurately and efficiently compensating for pitch, yaw, and roll moments created by thruster burning, leading to potential overshooting, undershooting, fuel wastage, and pointing errors, especially when using asymmetric thrusters that require complex control techniques.
Innovation Solution
A proportional derivative control system is implemented to generate thrust commands for flight vehicles, using feedback from attitude error quaternions and angular velocities to stabilize the vehicle's attitude, reduce fuel consumption, and compensate for moments caused by asymmetric thrusters, while also addressing center of gravity shifts and line-of-sight rate commands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional control systems are used with asymmetric thrusters, then attitude control is achieved, but the control techniques become computationally complex and fuel consumption increases
Solution Approach 1:
The patent transforms the complex nonlinear attitude control problem into a simpler linear control problem by changing the parameter representation from Euler angles to quaternions. This parameter transformation allows the use of linear proportional-derivative control techniques instead of complex nonlinear control algorithms, reducing computational complexity while maintaining control accuracy. The quaternion representation eliminates singularities and simplifies the mathematical model for asymmetric thruster configurations.
Solution Approach 2:
The patent replaces complex mechanical control reasoning with a mathematical substitution approach. By substituting the physical interpretation of asymmetric thruster moments with a mathematical transformation using quaternions and linear control equations, the system achieves the same control effect with simpler computation. The complex moment compensation requirements are substituted with straightforward linear feedback control calculations.
2Reliability
If conventional control systems are used with asymmetric thrusters, then attitude control is achieved, but fuel consumption increases
Solution Approach 1:
The patent implements a feedback mechanism using quaternions to represent attitude error and angular velocity. The proportional-derivative control law continuously feeds back the current attitude state and compares it with the desired attitude, generating thrust commands that minimize the error. This closed-loop feedback ensures accurate attitude control while optimizing fuel consumption by applying thrust only when and where needed, rather than using continuous or excessive thrust as in open-loop or poorly designed closed-loop systems.
Solution Approach 2:
By changing the control parameters from traditional Euler angle rates to quaternion-based attitude error and angular velocity, the system achieves more efficient fuel utilization. The quaternion representation provides a more direct and singularity-free path to the desired attitude, allowing the controller to compute optimal thrust commands that minimize fuel consumption while achieving the same attitude control accuracy.
3Ease of operation
If control accuracy is insufficient to compensate for thruster moments, then the system is easier to operate, but the flight vehicle overshoots or undershoots the desired path
Solution Approach 1:
The patent changes the control parameters to quaternions, which provide a more accurate and singularity-free representation of attitude. This parameter transformation enables the controller to accurately track the desired path without overshooting or undershooting, while the linear proportional-derivative control law keeps the system simple and easy to operate. The quaternion parameters directly relate to the thruster moments, enabling precise control with simple computation.
4Ease of manufacture
If marginal stability is used in the control system, then fuel consumption increases, but the system becomes easier to implement
Solution Approach 1:
By transforming the control parameters to quaternions and using linear proportional-derivative control, the patent achieves both easy implementation and fuel efficiency. The quaternion representation simplifies the mathematical model, making the system easy to implement, while the accurate attitude error calculation enables precise thrust commands that minimize fuel consumption. The linear control law is computationally simple yet highly effective at maintaining stable, fuel-efficient operation.
Data Source
AI summary
A system and method is provided for thruster control in a flight vehicle. The system and method uses a proportional derivative matrix control technique to determine thrust commands in a Divert and Attitude control (DAC) system. The proportional derivative matrix control system is configured to receive pitch, roll and yaw commands as inputs, and generate thrust commands as outputs. The performance of the proportional derivative matrix controller is such that the thrust commands can achieve the desired attitude angles quickly and with reduced fuel consumption. The matrix control system can efficiently control a variety of thrusters, including asymmetric thrusters having different moment arms. The matrix control system is particularly suitable to the control of DAC systems with asymmetric thrusters that are configured for attitude control.