A method to control a sunlight acquisition phase of a spacecraft with a nonzero angular momentum of an axis D.sub.H. The spacecraft includes a solar generator configured to rotate about an axis Y. The spacecraft actuators are controlled to place the spacecraft in an intermediate orientation in which the axis Y is substantially orthogonal to the axis D.sub.H. The solar generator is controlled to orientate the solar generator towards the sun. The spacecraft actuators are controlled to reduce the angular momentum of the spacecraft. The actuators of the spacecraft engine are controlled to place the spacecraft in an acquisition orientation in which the axis Y is substantially orthogonal to the direction of the sun with respect to the spacecraft.

The disclosure provides a method and apparatus for determination of a control policy for a rigid body system, where the rigid body system comprises a sensor and a plurality of actuators designed to maneuver the rigid body system and orient the sensor toward a plurality of defined vertices, such as geographic points on the earth surface. A processor receives input data describing an initial state of the rigid body system and further receives a plurality of candidate vertices for potential targeting by the sensor. The processor additionally receives an intrinsic value for each vertex, reflecting the relative desirability of respective vertices in the plurality of vertices. The processor determines an appropriate control policy based on the vertices, the intrinsic values, and the rigid body system through a formulation of the determination process as an optimization problem which actively considers various constraints during the optimization, such as maneuvering and observation constraints.

Apparatus and methods for controlling a spacecraft for a transfer orbit. The spacecraft includes a momentum subsystem that stores angular momentum relative to a center of mass of the spacecraft, and a propulsion subsystem that includes electric thrusters. A controller identifies a target spin axis for the spacecraft, determines gimbal angles for electric thruster(s) that so that thrust forces from the electric thrusters are parallel to the target spin axis, and initiates a burn of the electric thruster(s) at the gimbal angles. The controller controls the momentum subsystem to compensate for a thruster torque produced by the burn of the electric thrusters. The momentum subsystem is able to produce a target angular momentum about the center of mass, where a coupling between the target angular momentum and an angular velocity of the spacecraft creates an offset torque to counteract the thruster torque.

Described herein are systems and methods for attitude determination using infrared Earth horizon sensors (EHSs) with Gaussian response characteristics. Attitude information is acquired by detecting Earth's infrared electromagnetic radiation and, subsequently, determining the region obscured by Earth in the sensors' fields of view to compute a nadir vector estimation in the spacecraft's body frame. The method can be applied when two sensors, each with known and distinct pointing directions, detect the horizon, which is defined as having their fields of view partially obscured by Earth. The method can be implemented compactly to provide high-accuracy attitude within small spacecraft, such as CubeSat-based satellites.

A method of controlling the attitude of a spacecraft in spinning around itself with a non-zero total angular momentum H.sub.TOT. The spacecraft includes a set of inertia flywheels configured to form an internal angular momentum H.sub.ACT. The axis of the total angular momentum H.sub.TOT is aligned with a principal axis of inertia of the spacecraft, in the course of which the inertia flywheels are controlled to form an internal angular momentum H.sub.ACT. The following expression, in which J is the inertia matrix of the spacecraft:

H.sub.actJ.sup.1(H.sub.totJ.sup.1H.sub.tot)

is negative if the principal axis of inertia targeted is the axis of maximum inertia of the spacecraft and is positive if the principal axis inertia targeted is the axis of minimum inertia of the spacecraft.

A method controls an operation of a spacecraft according to a model of the spacecraft. The method determines control inputs for controlling concurrently thrusters of the spacecraft and momentum exchange devices of the spacecraft using an optimization of a cost function over a receding horizon subject to constraints on a pose of the spacecraft and constraints on inputs to the thrusters. The cost function includes components for controlling the pose of the spacecraft and a momentum stored by the momentum exchange devices. The method generates a command to control concurrently the thrusters and the momentum exchange devices according to at least a portion of the control inputs.

A multi-degree-of-freedom electromagnetic machine includes a first structure, a second structure, and a control. The first structure is configured to rotate about a spin axis and about a tilt axis that is perpendicular to the spin axis, and includes a first spin conductor, a second spin conductor, and a tilt conductor, which together form a general shape of a surface. The second structure is disposed adjacent to the first structure and includes a plurality of magnets. The control is configured to controllably supply alternating current (AC) to the first and second spin conductors and direct current (DC) to the tilt conductor, wherein the first structure continuously rotates about the spin axis in response to the AC being supplied to the first and second spin conductors, and rotates about the tilt axis to a tilt position in response to the DC being supplied to the tilt conductor.

A method controls an operation of a spacecraft according to a model of the spacecraft. The method determines control inputs for controlling concurrently thrusters of the spacecraft and momentum exchange devices of the spacecraft using an optimization of a cost function over a receding horizon subject to constraints on a pose of the spacecraft and constraints on inputs to the thrusters. The cost function includes components for controlling the pose of the spacecraft and a momentum stored by the momentum exchange devices. The method generates a command to control concurrently the thrusters and the momentum exchange devices according to at least a portion of the control inputs.

A method to control a sunlight acquisition phase of a spacecraft with a nonzero angular momentum of an axis D.sub.H. The spacecraft includes a solar generator configured to rotate about an axis Y. The spacecraft actuators are controlled to place the spacecraft in an intermediate orientation in which the axis Y is substantially orthogonal to the axis D.sub.H. The solar generator is controlled to orientate the solar generator towards the sun. The spacecraft actuators are controlled to reduce the angular momentum of the spacecraft. The actuators of the spacecraft engine are controlled to place the spacecraft in an acquisition orientation in which the axis Y is substantially orthogonal to the direction of the sun with respect to the spacecraft.

A method controls an operation of a spacecraft according to a model of the spacecraft. The method determines control inputs for controlling concurrently thrusters of the spacecraft and momentum exchange devices of the spacecraft using an optimization of a cost function over a receding horizon subject to constraints on a pose of the spacecraft and constraints on inputs to the thrusters. The cost function includes components for controlling the pose of the spacecraft and a momentum stored by the momentum exchange devices. The method generates a command to control concurrently the thrusters and the momentum exchange devices according to at least a portion of the control inputs.