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US 12,202,628 B2Granted
Attitude control system and method
AssigneeUrugus S.A.
InventorMariano Sternheim
Life of this patent
Estimating the term…
Abstract
Systems and method for controlling the attitude maneuvers of a spacecraft in space are provided. The method automatically generates optimal trajectories in real-time to guide a spacecraft, providing a much more robust and efficient method than predefined trajectories, to model errors or disturbances. These methods do not rely in predefined trajectories and their associated feed-forward term. The systems comprise sensors, attitude control mechanisms, and a control module to orient the spacecraft in real-time, such that the spacecraft reaches a desired target attitude following an optimal path in the state space and is locally and asymptotically stable.
Claims13
An on-board attitude control system for controlling attitude maneuvers of a vehicle, the system comprising:
- an attitude control mechanism operable to orient the vehicle;
- and
- a control module configured to, at each step of multiple steps of a path:
- determine, based at least in part on an attitude state estimated at each step of the multiple steps, and on a target attitude state, an attitude error;
- determine, based at least in part on the attitude error, weighting factors of a cost function;
- minimize the cost function to obtain a control action, wherein the cost function comprises a state error cost and a control effort cost;
- and
- direct the attitude control mechanism to perform the control action to orient the vehicle,
- wherein the weighting factors of the cost function are determined as a function of one or more zones of a state-space;
- wherein minimizing the cost function comprises solving an Algebraic Riccati Equation (ARE) using a Newton-Rapshon method with a predetermined maximum number of iterations, starting with an initial guess chosen to yield a globally stabilizing solution of a closed loop system, wherein if no optimal solution is found for minimizing the cost function after the predetermined maximum number of iterations, an intermediate result is used to determine the control action, and the intermediate result is used as a next iteration initial guess of a first iteration of a next step.
7 more elements
A satellite system comprising:
- at least one sensor configured to estimate attitude states of the satellite system;
- an on-board attitude control mechanism operable to orient the satellite system;
- and
- an attitude control module configured to, at each step of multiple steps of a path:
- determine, based at least in part on an attitude state estimated at each step of the multiple steps, and on a target attitude state, an attitude error, wherein the attitude state estimated at each step of the multiple steps is based at least in part on information from the at least one sensor;
- determine, based at least in part on the attitude error, weighting factors of a cost function;
- minimize the cost function to obtain a control action, wherein the cost function comprises a state error cost and a control effort cost;
- and
- direct the on-board attitude control mechanism to perform the control action to orient the satellite system;
- wherein the weighting factors of the cost function are determined as a function of one or more zones of a state-space;
- wherein minimizing the cost function comprises solving an Algebraic Riccati Equation (ARE) using a Newton-Rapshon method with a predetermined maximum number of iterations, starting with an initial guess chosen to yield a globally stabilizing solution of a closed loop system, wherein if no optimal solution is found for minimizing the cost function after the predetermined maximum number of iterations, an intermediate result is used to determine the control action, and the intermediate result is used as a next iteration initial guess of a first iteration of a next step.
8 more elements
A method for controlling attitude maneuvers of a vehicle, the method comprising, at each step of multiple steps of a path:
- determining, based at least in part on an attitude state estimated at each step of the multiple steps, and on a target attitude state, an attitude error;
- determining, based at least in part on the attitude error, weighting factors of a cost function;
- minimizing the cost function to obtain a control action, wherein the cost function comprises a state error cost and a control effort cost;
- and
- performing the control action to orient the vehicle;
- wherein the method further comprises determining the weighting factors of the cost function as a function of one or more zones of a state-space;
- wherein minimizing the cost function comprises solving an Algebraic Riccati Equation (ARE) using a Newton-Rapshon method with a predetermined maximum number of iterations, starting with an initial guess chosen to yield a globally stabilizing solution of a closed loop system, wherein if no optimal solution is found for minimizing the cost function after the predetermined maximum number of iterations, an intermediate result is used to determine the control action, and the intermediate result is used as a next iteration initial guess of a first iteration of a next step.
4 more elements
Dependencies are inferred from the claim text.