An operation of a spacecraft is controlled using an inner-loop control determining first control inputs for momentum exchange devices to control an orientation of the spacecraft and an outer-loop control determining second control inputs for thrusters of the spacecraft to concurrently control a pose of the spacecraft and a momentum stored by the momentum exchange devices of the spacecraft. The outer-loop control determines the second control inputs using a model of dynamics of the spacecraft including dynamics of the inner-loop control, such that the outer-loop control accounts for effects of actuation of the momentum exchange devices according to the first control inputs determined by the inner-loop control. The thrusters and the momentum exchange devices are controlled according to at least a portion of the first and the second control inputs.

Embodiments of a spherical momentum control device are provided. In one embodiment, the spherical momentum control device includes a housing assembly bounding a cavity, a rotor support axle disposed within the cavity, and a spherical bearing interface formed between the rotor support axle and the housing assembly. The spherical bearing interface facilitates rotation of the rotor support axle within the cavity about three orthogonal axes transecting substantially at the cavity center point. A rotor is mounted to the rotor support axle (e.g., through precision bearings) for rotation about a spin axis. The spherical bearing interface can assume any form for facilitating rotation of the rotor support axle about the orthogonal axes including, for example, a low friction plane bearing interface. In one embodiment, the spherical bearing interface includes rolling element bearings embedded in the cavity walls or embedded in enlarged end caps forming part of the rotor support axle.

Embodiments of a spherical momentum control device are provided. In one embodiment, the spherical momentum control device includes a housing assembly bounding a cavity, a rotor support axle disposed within the cavity, and a spherical bearing interface formed between the rotor support axle and the housing assembly. The spherical bearing interface facilitates rotation of the rotor support axle within the cavity about three orthogonal axes transecting substantially at the cavity center point. A rotor is mounted to the rotor support axle (e.g., through precision bearings) for rotation about a spin axis. The spherical bearing interface can assume any form for facilitating rotation of the rotor support axle about the orthogonal axes including, for example, a low friction plane bearing interface. In one embodiment, the spherical bearing interface includes rolling element bearings embedded in the cavity walls or embedded in enlarged end caps forming part of the rotor support axle.

A propulsion system for small artificial satellites comprises a plurality of engines (2) fixable to a frame (101) of a satellite (100); a control unit (3) connected functionally to the engines (2) for sending at least one activation signal (AS) for activating at least one engine (2); the system is selectively configurable at least between a first configuration in which at least one of the engines (2) is activated for correcting the orbit of the satellite (100) and a second configuration in which at least one of the engines (2) is activated for dispersing said satellite (100) relative to another adjacent satellite.

The present disclosure relates to an axial flux motor for a reaction wheel, and method of using and making the same. The motor includes a stator and a rotor. The stator comprises a printed circuit board (PCB) including a first motor coil. The rotor is coupled to a first ring-shaped magnet having an alternating pole arrangement. In a further embodiment, the rotor includes permanent magnets, and the stator PCB includes a first motor coil, and a first high thermal conductivity element.

The present disclosure relates to an axial flux motor for a reaction wheel, and method of using and making the same. The motor includes a stator and a rotor. The stator comprises a printed circuit board (PCB) including a first motor coil. The rotor is coupled to a first ring-shaped magnet having an alternating pole arrangement. In a further embodiment, the rotor includes permanent magnets, and the stator PCB includes a first motor coil, and a first high thermal conductivity element.

Disclosed are an attitude estimation method, a terminal, a system and a computer-readable storage medium. For the problem of attitude and sensor bias estimation, a cascade solution method is provided. The first part of the cascade is a Kalman filter applied to an LTV system, and the second part of the cascade is a nonlinear attitude observer built in SO(3). In the estimation process, only one constant inertial reference vector needs to be measured explicitly in body-fixed coordinates, and the complexity of the attitude estimation algorithm is greatly simplified by exploiting the geometric relationship between the inertial reference vector and the Earth angular velocity vector. At the same time, the time-varying characteristics of the implemented Kalman filter help to avoid the tedious empirical gain adjustment process that often relies on sets of piecewise constant gains, to improve the convergence speed of the algorithm.

A control system configured to execute a safing mode sequence for a spacecraft is disclosed. The control system includes one or more star trackers that each include a field of view to capture light from a plurality of space objects surrounding the celestial body. The control system also includes one or more actuators, one or more processors in electronic communication with the one or more actuators, and a memory coupled to the one or more processors. The memory stores data into a database and program code that, when executed by the one or more processors, causes the control system to determine a current attitude of the spacecraft, and re-orient the spacecraft from a current attitude into a momentum neutral attitude.

A spacecraft attitude control module (1) according to the invention is compact and easy to assemble with additional modules to form an operative attitude control system. The module comprises a robust rectangular, preferably cubic support frame with an attitude control assembly fitted within the confines of the support frame, the assembly including a reference structure comprising a platform, a flywheel support structure (15, 18, 19, 26) and a flywheel (25). The flywheel support structure may be fixed to the platform (10) or it may be a gimbal structure that is rotatable relative to the platform. In the first case the module is a reaction wheel module. In the second case the module is a single gimbal control moment gyroscope module. A preferred embodiment includes a slanted position of the platform (10) relative to the ground plane (100) of the support frame. Another preferred characteristic is the implementation of a flywheel provided with a hollow portion (25′) into which the motor (28) that is driving the flywheel rotation is fitted. The invention is also related to an attitude control system comprising multiple modules assembled together on a support plate (35). The modules may be provided with decking plates (39, 39′) to improve the mechanical robustness of the assembly and to realize fast electrical connections to the modules.

A spacecraft has a flat antenna array having an edge and a middle portion. A reconfigurable reaction-momentum wheel is coupled to the antenna array to roll and/or pitch the antenna array in small magnitudes. The reconfigurable reaction-momentum has a reaction operating state or mode (high-torque, low momentum) and a momentum operating state or mode (low-torque, high momentum). A thruster is coupled to the antenna array to move the antenna array.