M. Yu. Ovchinnikov

Passive Magnetic Attitude Control System for the Munin Nanosatellite

The instrumental and applied problems related to the design of a passive magnetic attitude control system for the Munin nanosatellite are considered. The system is constructed from a strong permanent magnet and a set of hysteresis rods. These rods are made of magnetically soft material using a special technology, and they allow us to support the satellite orientation with respect to the local magnetic field vector with a given accuracy and time response. By using asymptotic and numerical methods, we investigate the satellite dynamics for different models of hysteresis. The issues concerning the arrangement of the rods and their interaction with the fields of permanent magnets mounted onboard the satellite are discussed.

Investigation of the effectiveness of an algorithm of active magnetic damping

We consider the rapid rotation of a satellite equipped with an active magnetic attitude control system with the -Bdot algorithm designed to damp the initial angular velocity. The time-response of the algorithm is analytically studied as a function of orbit inclination.

Testing of attitude control algorithms for microsatellite Chibis-M at laboratory facility

A laboratory facility developed at the Engineering Technological Center “Scan Ex” for testing algorithms for determination of attitude and stabilization of the attitude system of the satellite “Chibis-M” is described. The results of experiments on damping initial angular rotation, using magnetorquers, stabilization of the mock-up using flywheels, and flywheel unloading are analyzed. The operation of the algorithm for determination of the mock-up attitude is studied; the main characteristics of this algorithm are the accuracy of the state vector estimation and the time of convergence.

Laboratory study of magnetic properties of hysteresis rods for attitude control systems of minisatellites

Results of the experimental determination of the parameters of hysteresis rods made of soft magnetic materials used in passive attitude control systems to damp the perturbed motion of satellites relative to their center of mass are described. Based on the classical solution of the linear magnetization problem and an approximate solution of the problem of nonlinear magnetization in a variable magnetic field, it is shown that the considerable distortion in the experimental determination of the parameters is explained by eddy currents induced in the rods. To mitigate the effect of those currents, it is shown that the measurements must be performed when the frequency of the magnetic fields variation is not higher than 0.1–0.2 Hz. Using nonlinear magnetization theory, a procedure for the experimental determination of the parameters of hysteresis rods is developed. This procedure is augmented by the corresponding computer processing of weak valid signals. The procedure can be used for the choice of the parameters of damping devices included in satellite passive attitude control systems.

A laboratory facility for verification of control algorithms for a group of satellites

A laboratory facility LuVeX consisting of a smooth horizontal table and models moving on its surface was developed at ZARM for adjustment of control algorithms for group motion of satellites. This paper describes the facility and implemented control algorithms for air-breathing pulsed jet engines mounted on moving models to provide their translational and rotational motion. The facility performance is proved by the results of numerical simulation of the control algorithm for the motion of a group of models along a given trajectory.

A study of angular motion of the Chibis-M microsatellite with three-axis flywheel control

We study the controlled angular motion of the Chibis-M microsatellite. Executive elements are three pairs of flywheels, whose axes are mutually perpendicular. The task of the control system is realization of a required program motion and support of its asymptotic stability. In this paper, we synthesize a control algorithm and study the evolution of the angular momentum of flywheels on long time intervals. The attitude accuracy is estimated for the case when disturbances act upon the spacecraft.

Attitude control of a rigid body suspended by string with the use of ventilator engines

Axial motion of a balloon payload with respect to the center of mass under action of ventilator engines is studied. An implementation of a control algorithm is suggested. The possibility of using ventilator engines for trajectory tracking is examined. A technique for determining engine parameters and results of laboratory tests of a system mock-up are presented.

Attitude control system of the first Russian nanosatellite TNS-0 no. 1

The results of designing the attitude control system of the first Russian nanosatellite TNS-0 no. 1 providing orientation of its longitudinal axis along the local geomagnetic field induction vector are presented. The system consists of a permanent magnet and two sets of hysteresis rods. The magnetic and geometric parameters of the magnet and rods are calculated. The influence of the permanent magnet field on the hysteresis rods and mutual influence of the rods in the case of compact satellite packaging are analyzed. Examples of calculations of transient processes and steady-state angular satellite motion are presented.

Elimination of relative secular drift of orbits of two satellites caused by polar oblateness of the Earth

A method of elimination of relative secular drifts in satellite formations is suggested for the case of influence of a perturbation due to polar oblateness of the Earth. The method is applied to eliminate relative secular drifts in the case when a satellite is controlled using an engine mounted along its orientation axis (the satellite is supplied with a passive magnetic attitude control system) and with the help of a solar sail installed on one of the satellites. Analytical results are confirmed by numerical simulation.

Nanosatellite REFLECTOR: Choice of parameters of the attitude control system

We consider methodological and applied problems of choosing parameters and developing a passive gravity-gradient attitude control system for the REFLECTOR nanosatellite. The attitude control system consists of appropriately distributed satellite mass and additional masses forming the required tensor of inertia, as well as of a set of hysteresis rods manufactured from a magnetically soft material. The combination of these elements allows one, independent of the satellite’s initial angular motion, to maintain its three-axial orientation in the orbital coordinate system with preset performance in precision and fast response. The satellite’s dynamics is investigated using asymptotic and numerical methods. The problems of arrangement of the additional masses and hysteresis rods are discussed, as well as their interaction with magnetizable elements.