RU145978U1 - SYSTEM OF ORIENTATION AND STABILIZATION OF THE TABLETSAT MICRO-SATELLITE PLATFORM - Google Patents

Abstract

Orientation and stabilization system of the microsatellite platform "Tabletsat" containing at least five solar sensors, at least one three-component magnetometer, three uniaxial angular velocity sensors, power flywheel control motors and an orientation system control unit, characterized in that as orientation detection sensors additionally use a three-component angular velocity sensor and a stand-alone star sensor; three power electromagnetic coils are used as an angular stabilization system and control disposed coaxial axes of the coordinate system associated with the microsatellite platform, at least three power control of the engine-flywheel rotation axes are not parallel at least three power gyrodyne whose axes are disposed in nonparallel planes.

Description

The utility model relates to spacecraft, namely to the systems of orientation and stabilization of microsatellites.

The orientation and stabilization system is used to determine the angular motion of the satellite around the center of mass, as well as to control the motion of the satellite around the center of mass. Depending on the tasks, some devices do not require orientation, others require the camera to be oriented to the Earth with high accuracy, the third must be twisted around one of the axes and rotated at a constant speed, etc. In this case, various requirements may arise for the accuracy of determining the orientation, the number of determined parameters, and so on. The proposed utility model is intended for triaxial stabilization of the satellite and determination of the angular position and angular velocity of rotation of the satellite with medium accuracy. Such orientation systems, as a rule, are installed on satellites of remote sensing of the Earth of medium accuracy.

The known system of orientation and stabilization of the microsatellite "Chibis-M", consisting of sensors for determining orientation, executive bodies and the control unit of the orientation system. As sensors for determining orientation in the composition of the microsatellite, a magnetometer, illuminated sensors and uniaxial angular velocity sensors are used.

Three current coils and six flywheel control motors are used as executive elements of the orientation control system in the microsatellite. Flywheel engines are based on a non-contact direct current motor with a controlled torque and are intended for use as an executive body in microsatellite orientation and stabilization systems. The electric motor provides rotation of the rotor-flywheel and its braking. The magnitude of the torque (control) created by it can smoothly change in a given range in accordance with the control signal supplied to the input of the flywheel engine.

The control unit for the orientation and stabilization system is the link between the sensors and controls, as well as between the orientation and stabilization system and external control devices.

A disadvantage of the known system is its limited use due to the fact that the flywheels, as well as the flywheel and coil control units are located inside the system. (Source: D. Ivanov et al. "Flight tests of the Chibis-M microsatellite orientation control algorithms, IPM Preprints named after MV Keldysh, 2012, No. 58, URL: http: //library/keldysh.ru /preprint.asp?id=2012-58).

The objective of this utility model is to create a flexible and flexible orientation and stabilization system that will expand the scope of the system for satellites from 10-50 kg to 100 kg satellites and provide a wide range of functions while increasing the accuracy of determining orientation and stabilization.

The technical result, objectively manifested when using a utility model, is to increase the manufacturability of the device.

The essence of the technical solution lies in the fact that the flywheels, the flywheel control unit, the coil control unit are placed in separate devices, and a single control unit has been created for their control, providing flexibility in the configuration of the necessary orientation system devices.

The technical result is achieved by the fact that in the known orientation and stabilization system containing less than five solar sensors, at least one three-component magnetometer, three uniaxial angular velocity sensors, power flywheel control motors and an orientation control unit are additionally used as detection sensors orientation three-component angular velocity sensor and a stand-alone star sensor; as a system of angular stabilization, three power electromagnetic control coils are used, located coaxially to the axes of the coordinate system associated with the microsatellite platform; at least three power control flywheel engines whose rotational axes are not parallel; at least three power gyrodines whose axes are located in non-parallel planes.

The essence of the utility model is explained in the following graphic materials.

Figure 1 - arrangement of elements of the orientation and stabilization system in the body of the microsatellite;

Figure 2 - General view of the control unit of the orientation and stabilization system

In Fig 3 - schematically shows the maximum configuration of the control unit orientation and stabilization system;

figure 4 - Mode damping angular velocity;

figure 5 - Safe mode;

figure 6 - Rough uniaxial orientation mode;

Fig.7 - Orientation mode on the Sun;

on Fig - Rough triaxial orientation mode;

figure 9 - Mode of accurate triaxial orientation;

figure 10 - Mode retargeting;

figure 11 - mode of unloading flywheels

Figure 1 presents the orientation and stabilization system of the microsatellite platform "Tabletsat", where 1 - solar sensors, 2 - magnetometer, 3 - DOS, 4 - star sensor; 5 - EMU; 6 - flywheel; 7 - hydrodin; 8 - control unit of the orientation and stabilization system.

The orientation and stabilization system contains an orientation system that forms the orbital instrument coordinate system of the orbital coordinate system and measures the angles of the microsatellite platform relative to the constructed coordinate system, the associated coordinate system (SSC) and the angular stabilization system that holds the connected axes of the microsatellite platform relative to the constructed coordinate system.

When the microsatellite platform is oriented in the OXo Yo Zo orbital coordinate system, the vertical axis of the OZ microsatellite platform (MP) OZ is directed along the line of the center of mass of the Earth — the center of mass of the MP, the longitudinal axis of the OY MP is directed toward the flight and aligned with the orbit plane, the axis of the OX MP complements the coordinate system to the right.

The orientation and stabilization system includes orientation detection sensors, actuators and a control unit for the orientation system.

At least five solar sensors (DM) 1, at least one three-component magnetometer (MM) 2, three uniaxial angular velocity sensors ADIS 16130 and a three-component angular velocity sensor (DLS) 3, autonomous stellar are used as orientation sensors in the microsatellite composition; sensor - 4.

Unlike the closest analogue, the proposed solution uses an autonomous star sensor 4, which allows to increase the accuracy of determining the orientation and stabilization. In addition, using the star sensor 4, you can calibrate all other sensors. The accuracy of the used three-component magnetometer and three-component angular velocity sensor "Tabletsat" is higher. A three-component magnetometer HMR 2300R and three single-axis angular velocity sensors ADIS 16130 are used as spare.

As a system of angular stabilization using:

1) three power electromagnetic control coils (EMU) 5 located coaxially to the axes of the coordinate system associated with the microsatellite platform;

2) at least three power control flywheel engines (UDM). In this case, the axis of rotation of the flywheels 6 should not be mutually parallel.

3) at least three power gyrodines 7. The axes of gyrodines are located in non-parallel planes.

The advantages of this design are that if the control unit for the stabilization and orientation system (BUSOS) 8 fails, the satellite's viability is maintained by interconnecting the magnetometer 2 with the control unit EMU 5 and implementing the simplest stabilization algorithm. And it is also possible to configure the stabilization system from a different number of flywheel engines 6 and gyrodines 7, since they are included in a single control loop.

Flywheel engines 6 are made on the basis of a non-contact direct current motor with a controlled moment and are intended for use as an executive body in microsatellite orientation and stabilization systems. The electric motor provides rotation of the rotor-flywheel and its braking. The magnitude of the torque (control) created by it can smoothly change in a given range in accordance with the control signal supplied to the input of the flywheel engine. The mechanical moment from the flywheel control engines is created when their rotation speed changes and is in the range [-0.4, +0.4] mN · m in laboratory conditions. The speed of rotation of the flywheels in this case varies in the range [-20,000, +20000] rpm.

The control unit of the orientation and stabilization system 8 is a connecting link between the sensors and controls, as well as between the orientation and stabilization system and external control devices. The main functions of the unit are the collection and processing of sensor readings using orientation determination algorithms, the generation of commands for stabilization system elements using control algorithms, the reception of commands from an external onboard microsatellite control controller, and the transmission of data to satellite telemetry channels. The main component is an on-board computer, which is based on the LPCH2294 board containing a processor, an external RAM of 1 MB in size, and non-volatile flash memory with a capacity of 4 MB.

The placement of the control unit of the orientation and stabilization system, the angular velocity sensors, the magnetometer, the flywheel control engine, gyrodines, and the electromagnetic device is possible both on the external and internal panels of the leaky housing of the microsatellite platform; a solar sensor and a star sensor are located on the external panels of the microsatellite platform. Maximum length of connecting cables from BUSOS to EMU 2 m; from BUSOS to a solar sensor, a star sensor, a magnetometer, a flywheel control engine, 1 m gyrodynes. The magnetometer should be located farthest from sources of a disturbing magnetic field, for example, an electromagnetic device (electromagnetic control coil), a flywheel control engine. The angular accuracy of the installation of sensors and control elements relative to the seating surfaces is not worse than 6 angles. min

The control unit of the orientation and stabilization system 8 is capable of transmitting telemetry packets to the external systems about the functioning of the instruments in its composition; SOS operating modes; MP orientation parameters; acknowledgment of receipt of commands. To perform these tasks, the BUSOS must receive the following initial data from external systems: the exact time with a frequency of at least 600 seconds or, upon request, with an accuracy of time stamps of 1 millisecond; ballistic orbital parameters in TLE format with update intervals of at least 48 hours; duration of autonomous motion prediction with their use up to 7 days; commands for controlling the operating conditions of the SOS; SOS calibration parameters; fragments of executable code.

Unlike the analogue, where the exact orientation modes of the analogue are provided only near the orbital orientation, in the proposed solution, the precise orientation modes of the “Tabletsat” are provided regardless of orientation.

The exchange of information between the components of the nodes of the microsatellite platform is carried out using the CAN interface. The CAN network of the microsatellite uses an adapted high-level protocol; messages are exchanged between CAN network subscribers using messages of a fixed structure. A high-level protocol add-in structures the description of the CAN_ID header, highlighting the addresses of the receiver and sender, and the standard CAN message format is described in the CAN_ID protocol. All command messages contain bytes that describe the type of command and the virtual module of the device to which the command is sent. In messages consisting of several CAN packets, one packet is allocated under the header, which also describes the length and time of the formation of this message. Thanks to the introduction of this protocol, data exchange between physical devices is unified and software development is optimized, due to the possibility of code reuse, the ability to transmit messages of arbitrary length is achieved. It also becomes possible to create several virtual modules on one physical device, which in case of a lack of identifiers for all devices in the satellite network allows placing up to 256 devices on one CAN_ID and significantly expanding the capabilities of the 11-bit CAN protocol.

The proposed design of the orientation and stabilization system allows you to expand the scope of the system for satellites from 10-50 kg to 100 kg satellites and to provide a wide range of tasks. Figure 3 schematically shows the maximum configuration of the system, figure 4-11 lists the possible options for the algorithms and the necessary minimum configurations to ensure the operation of the algorithms and the accuracy characteristics resulting from the operation of the algorithms. Algorithms are divided into various goals and objectives of use.

The spacecraft’s orientation and stabilization system is one of the on-board systems and the full life cycle of the spacecraft operates, providing a certain position of the vehicle’s axes relative to some given directions (orientation), as well as maintaining the same direction of the vehicle’s axes when moving from one orbit to another, moving to the descent when the main propulsion system (stabilization) is working.

Based on the tasks to be solved, the proposed orientation and stabilization system ensures the operation of the microsatellite platform in the following modes:

1) Angular velocity damping mode;

2) Safe mode;

3) Rough uniaxial orientation mode;

4) Sun orientation mode;

5) Rough triaxial orientation mode;

6) Precise triaxial orientation mode;

7) Re-targeting mode;

8) Flywheel unloading mode

The safe mode and the orientation mode on the Sun contribute to the charging of solar panels. The coarse uniaxial orientation mode, the coarse triaxial orientation mode, the accurate triaxial orientation mode and the re-targeting mode are used to perform various targets (scientific experiments in space, navigation measurements, remote sensing of the Earth). The flywheel unloading mode extends the operating time of the Sun orientation modes, rough and accurate triaxial orientation. And the angular velocity damping mode prepares the apparatus for the operation of orientation modes on the Sun, rough triaxial orientation, accurate triaxial orientation and reorientation.

The following describes the operation of the system in different modes.

1) Angular velocity damping mode.

This mode is used in the case of rotation of a small spacecraft with a high angular velocity. Using the measurements of the magnetometer and the operation of the EMU, the angular velocity decreases, without providing any orientation (Figure 4).

Orientation of the coordinate system related to the microsatellite platform relative to the orbital SC:

- initial: arbitrary;

- final: arbitrary.

The angular velocity of rotation of the coordinate system associated with the microsatellite platform relative to the inertial SC:

- initial: up to 6 ° / s;

- final: no more: 0.5 ° / s.

The maximum duration of the transition to the specified mode should be no more than 1.5 hours.

2) Safe mode.

This mode is used to rotate the device with solar panels in the Sun with minimal energy consumption using a magnetometer and solar sensors to determine the orientation and the EMU for stabilization (Figure 5).

Orientation of the coordinate system associated with the microsatellite platform:

- initial: arbitrary;

- final: maintaining orientation to the Sun with an accuracy of at least ± 20 degrees with minimal energy consumption.

The angular velocity of rotation of the coordinate system associated with the microsatellite platform relative to the orbital SC:

- initial: up to 6 ° / s;

- final: not more than 1 ° / s.

The maximum duration of the transition to the specified mode should be no more than 1.5 hours.

3) Rough uniaxial orientation mode.

This mode supports coarse uniaxial orientation in the orbital coordinate system using a magnetometer, solar sensors to determine the orientation, and EMU for control (Fig.6).

Orientation of the coordinate system related to the microsatellite platform relative to the orbital SC:

- initial: arbitrary;

- final: maintaining uniaxial orbital orientation of an arbitrary axis with an accuracy of at least ± 20 °.

The angular velocity of rotation of the coordinate system associated with the microsatellite platform relative to the orbital SC:

- initial: up to 6 ° / s;

- final: no more than 0.5 ° / s.

The maximum duration of the transition to the specified mode is not more than 1.5 hours.

4) Sun orientation mode.

This mode ensures the rotation of the device by solar batteries in the sun with high accuracy. Solar sensors are used to determine orientation, and flywheels and / or gyrodynes are used as control bodies (Fig. 7)

Orientation of the coordinate system associated with the microsatellite platform:

- initial: arbitrary;

- final: Orientation by a given axis to the Sun with an accuracy of no more than 0.5 degrees.

The angular velocity of rotation of the coordinate system associated with the microsatellite platform relative to the orbital SC:

- initial: not more than 0.5 ° / s;

- final: not more than 0.005 ° / s.

The maximum duration of the transition to the specified mode should be no more than 600 seconds.

5) Rough triaxial orientation mode.

This mode provides the triaxial orientation of the device in the orbital coordinate system with low accuracy to perform the target task, for example, remote sensing of the Earth. A magnetometer, solar sensors, possibly an angular velocity sensor can be used to determine the orientation, and to control the flywheels and / or gyrodines (Fig. 8).

Orientation of the coordinate system associated with the microsatellite platform with respect to the orbital / inertial SC:

- initial: arbitrary;

- final: triaxial orientation of the SSC relative to the USC / SSC with an accuracy of at least 1 °. Error (σ) in determining the orientation: not more than 0.5 °.

The angular velocity of rotation of the coordinate system associated with the microsatellite platform relative to the orbital / inertial SC:

- initial: not more than 0.5 ° / s;

- final: angular stabilization with an error (σ) of not more than 0.05 ° / s.

The maximum duration of the transition to the specified mode should be no more than 600 seconds.

6) Precise triaxial orientation mode.

This mode provides the triaxial orientation of the device in the orbital coordinate system with high accuracy to perform the target task, for example, remote sensing of the Earth. A star sensor, a magnetometer, solar sensors, an angular velocity sensor can be used to determine the orientation, and flywheels and / or gyrodynes for control (Fig. 9).

Orientation of the coordinate system associated with the microsatellite platform with respect to the orbital / inertial SC:

- initial: triaxial orientation of the SSC relative to the USC / SSC with an accuracy of at least 1 °;

- final: triaxial orientation of the SSC relative to the USC / SSC with an accuracy of at least 0.003 ° (10.8 ″).

Orientation error (σ): not more than 0.001 ° (3.6 ″) °.

The angular velocity of rotation of the coordinate system associated with the microsatellite platform relative to the orbital / inertial SC:

- initial: not more than 0.05 ° / s;

- final: angular stabilization with an error (σ) of not more than 0.001 ° / s.

The maximum duration of the transition to the specified mode should be no more than 10 seconds.

7) Retargeting mode.

This mode provides the triaxial orientation of the device in an arbitrary direction to the orbital coordinate system with high accuracy to perform the target task, for example, remote sensing of the Earth. In this case, it is possible to perform constant turns according to a predetermined law. A star sensor, a magnetometer, solar sensors, an angular velocity sensor can be used to determine the orientation, and flywheels and / or gyrodynes for control (Figure 10).

Orientation of the coordinate system associated with the microsatellite platform with respect to the orbital / inertial SC:

- initial: triaxial orientation of the CCK relative to the USC / ISK, with an accuracy of at least 0.003 ° (10.8 ″);

- final: triaxial orientation of the SSC relative to the USC / SSC, different from the initial one. Orientation accuracy of at least 0.003 ° (10.8 ″);

- The maximum output frequency of the new desired orientation is 5 Hz.

Orientation error (σ): not more than 0.001 ° (3.6 ″) °.

The angular velocity of rotation of the coordinate system associated with the microsatellite platform relative to the orbital SC:

- initial: no more than 0.001 ° / s, if the MP is in the exact triaxial orientation mode, or no more than 2 °, if the MP is in the redirection mode;

- final: no more than 2 ° / s.

The maximum duration of work in a given mode is at least 1.5 hours.

8) Flywheel unloading mode.

In the case of long-term operation of any of the modes using flywheels and / or gyrodynes, the unloading mode of the flywheels allows using the EMU to reduce the speed of rotation of the flywheels and to reduce the measure of the singularity of the gyrodynamic system without losing orientation (Fig. 11).

Orientation of the coordinate system associated with the microsatellite platform with respect to the orbital / inertial coordinate system (OSK / ISK):

- initial: triaxial orientation of the associated coordinate system relative to the orbital / inertial coordinate system (OSK / ISK), with an accuracy of at least 0.003 ° (10.8 ″);

- during the unloading period and final: triaxial orientation of the SSC relative to the USC / SSC, not different from the initial. Orientation accuracy of at least 0.003 ° (10.8 ″).

Orientation error (σ): not more than 0.001 ° (3.6 ″) °.

The angular velocity of rotation of the coordinate system associated with the microsatellite platform relative to the orbital SC:

- initial: not more than 0.001 ° / s;

- during the unloading period and final: not more than 0.001 ° / s.

Flywheel angular rotation speed:

- initial: more than nominal;

- final: less than nominal.

The maximum duration of work in a given mode is at least 1.5 hours.

Features of the electrical interface

- range of external supply voltage: 5 or 12B ± 10%;

- maximum consumption: no more than 60 W for up to 1 min;

- average consumption: no more than 20 watts;

- consumption in damping mode: no more than 8 W for up to 2 hours

- consumption in the mode of triaxial orientation, orientation to the Sun: no more than 16 watts.

- consumption in retargeting mode: not more than 35 W for up to 30 minutes.

- the uncompensated magnetic moment of the magnetic field on each axis should be no more than 0.05 A · m2 (50 units of CGSM).

The power supply to the SOS devices is turned on and off by the power supply system, which is external to the BUSOS system. Measures are also provided to protect the SOS equipment from static electricity.

Thus, the claimed orientation and stabilization system meets various requirements for the orientation of a microsatellite weighing from 10-50 kg to 100 kg, due to the proposed design of the device, operational qualities are improved and maintainability is increased. At the same time, the task of increasing the accuracy of determining orientation and stabilization is being solved.

The list of accepted abbreviations.

BOO - Control block BUSOS - control unit for orientation and stabilization system DUS - angular velocity sensor ZD - star sensor SUIT - inertial coordinate system MP - microsatellite platform MM - magnetometer USC - orbital coordinate system SC - coordinate system SOS - orientation and stabilization system SSK - linked coordinate system BOT - power supply system UDM - flywheel control engine CM - center of mass EMU - electromagnetic device Tle - two line elements

Claims (1)

Orientation and stabilization system of the microsatellite platform "Tabletsat", containing at least five solar sensors, at least one three-component magnetometer, three uniaxial angular velocity sensors, power flywheel control motors and an orientation control unit, characterized in that as orientation detection sensors additionally use a three-component angular velocity sensor and a stand-alone star sensor; three power electromagnetic coils are used as an angular stabilization system and control disposed coaxial axes of the coordinate system associated with the microsatellite platform, at least three power control of the engine-flywheel rotation axes are not parallel at least three power gyrodyne whose axes are disposed in nonparallel planes.