RU193079U1 - Ultra Small Spacecraft Orientation Module - Google Patents

Abstract

The utility model relates to the field of space technology, in particular, to the orientation system of an ultra-small spacecraft (SMKA). An orientation module (MO) for an ultra-small spacecraft is proposed, comprising a digital triaxial angular velocity sensor, a digital triaxial accelerometer, a digital triaxial magnetometer, a digital temperature sensor, a solar sensor, a horizon sensor, read-only memory and a duplicated communication channel connected to the calculator, while the orientation module is made on one printed circuit board enclosed in a housing with a solar sensor optical system. The technical result consists in increasing the reliability of determination orientation, simplifying the calibration of MOs, increasing the informational autonomy of MOs, increasing the rigidity of mechanical communication of composite sensors of the orientation system, removing the computational load from the orientation control unit, improving manufacturability. The technical result is achieved by the fact that the above sensors are allocated in a separate physical and functional module, which allows to build a fault-tolerant system with increased reliability on the basis of this module. MO performs a specific final function and has duplicated communication channels. Depending on the field of view of the optical sensors and the features of the mission at the QMS, two MOs will be required. The orientation will be determined if at least one MO with at least one communication channel is intact.

Description

The utility model relates to the field of space technology, in particular, to the orientation system of a very small spacecraft (SMKA).

Many missions require QMS orientation functions. For this, at present, various sensors are used at the SMKA, such as: solar sensor, horizon sensor, accelerometer, angular velocity sensor, magnetometers. Since each sensor has its own installation requirements, they are usually installed in different places on the spacecraft. Optical sensors are located on external faces, and a magnetometer is located at a maximum distance from the magnetic field of the SMKA. All orientation sensors must have a rigid mechanical connection with the spacecraft body. Some sensors complement each other, for example, the readings of angular velocity sensors can be refined by the readings of solar sensors and magnetometers. Thus, all orientation sensors work together and the solution to the orientation problem is based on the totality of the readings of all sensors.

The prior art system for determining the spatial position and course of an aircraft, comprising a block of angular velocity sensors, a block of linear acceleration sensors, a three-component magnetometer connected via an analog-to-digital converter to a computer with a logical unit connected to it, characterized in that it is additionally introduced temperature sensors of an angular velocity sensor block, a linear acceleration sensor block, a three-component magnetometer connected via an analog-to-digital converter An index to the calculator, and a switching unit, a buffer stage, a pairing module, an interface node connected to the calculator connected in series. This system is described in patent RU 2505786 C2.

The prior art is known for the orientation and stabilization system of the microsatellite platform "Tabletsat", comprising 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 sensors for determining the orientation, a three-component angular velocity sensor and an autonomous star sensor are additionally used; three forces are used as an angular stabilization system s control electromagnetic coil disposed coaxially with the 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. This system is described in patent RU 145978 U1.

Closest to the technical nature of the proposed technical solution is a device protected by patent RU 2505786 C2. This is a system for determining the spatial position and course of an aircraft without executive bodies and with a set of sensors for inertial navigation.

These sensor systems have several disadvantages. Due to the large weight and size characteristics, they cannot be installed on the SMKA. For the same reason, duplication is not possible. On the other hand, not every mission requires orientation management, its definition is enough, therefore executive bodies are not always needed.

Disclosure of the claimed technical solution.

The objective of the claimed utility model is to create an orientation module for QMSA (MO), calibrated, capable of producing a calculated orientation vector, based on which a redundant orientation system can be built.

The technical result consists in creating a MO suitable for use on the QMSA, increasing the reliability of determining the orientation, simplifying the calibration of the MO, increasing the information autonomy of the MO, increasing the rigidity of the mechanical connection of the composite sensors of the orientation system, removing the computational load from the orientation control unit, and improving manufacturability.

The indicated technical result is achieved by the fact that the sensors listed above are allocated in a separate physical and functional module, which makes it possible to build a fault-tolerant system with increased reliability on the basis of this module. MO performs a specific final function and has duplicated communication channels. Depending on the field of view of the optical sensors and the features of the mission at the QMS, two MOs will be required. The orientation will be determined if at least one MO with at least one communication channel is intact.

MO, using a duplicated communication channel and being in the same communication network, can communicate with each other. Exchange optical landmark information and other data to improve orientation accuracy. For example, the Sun is in the field of view of only one MO. This MO based on the Sun determines the rotation speed of the MCA and reports this information to other MOs, which according to these data adjust the zeros of their angular velocity sensors.

An important part of the orientation module is the mutual calibration of all sensors. In case of disparate placement of sensors, such calibration should be carried out after assembly of the entire QMSA, with all systems, and this complicates the calibration and increases the availability requirements of all systems. On the other hand, the MO is calibrated after the MO assembly. Calibration tables are stored in the memory of the MO itself, which also indicates its autonomy.

The sensors were initially logically connected: based on the totality of the readings of all the sensors that make up the MO, the position of the QMS in various coordinate systems is calculated. Since the sensors are located on one board and are processed by one controller located on the same board, it becomes possible for one MO to determine the orientation of the QMSA. If the Sun and the Earth fall into the field of view of this sensor, then the problem is solved completely in the Sun-Earth coordinate system, if these optical data are not available, then in the inertial coordinate system.

Since the sensors are located on one board, their mechanical connection is as rigid as possible compared to if they were on different boards in the SMKA connected by a chain of various structural elements.

Since orientation is calculated in the sensor itself, most of the computational load is removed from the orientation control unit. Consequently, the spacecraft’s orientation control unit (CUI) is simplified, or other QMS systems can take over its functions, for example, an onboard central computer module. In the case of using the BWO, its duplication is simplified.

Technological effectiveness consists in minimizing the processes of placing one MO in the QMSA, in comparison with the placement of six heterogeneous sensors that are part of the MO. While the weight and size characteristics of MO and SD are comparable.

Thanks to the use of a modern element base, the geometric dimensions of the sensor do not exceed 11 × 18 × 43 mm, and the mass does not exceed 10 g. Power consumption within 0.5 W with a frequency of orientation vector output of 10 Hz and the operation of all sensors at once.

A description of the device is illustrated in FIG. 1, 2, 3, 4.

The figure 1 shows a structural diagram of the proposed MO.

The figure 2 shows the PP module orientation from the side of the optical sensors.

The figure 3 shows the orientation module assembly from the side of the optical sensors.

Figure 4 shows the orientation module assembly from the side of WMO.

In the figures indicated:

1. Digital triaxial MEMS accelerometer.

2. The horizon sensor.

3. Digital triaxial magnetometer.

4. Digital triaxial MEMS angular velocity sensor.

5. The calculator MO.

6. Digital temperature sensor.

7. Solar sensor.

8. Duplicated communication channel.

9. Permanent storage device.

10. External duplicated communication bus.

11. The printed circuit board of the orientation module.

12. CMOS sensor array.

13. The housing of the orientation module.

14. The optical system of the solar sensor.

15. A connector for connecting to an external redundant communication bus.

Description of the device in statics.

MO consists of one printed circuit board (PCB) with soldered electronic components and a housing with an optical system necessary for optical sensors. PP and MO case are connected by screws. The MO calculator is a microcontroller or FPGA with the necessary components for their operation. The solar sensor (LED) is an optical sensor that can be based both on a CMOS sensor (see US Pat. No. 7,552,026 B2) and on photodiodes. A necessary quality of LEDs is a flat optical system such that MO can be installed on the outer edge of the SMKA. SD defines two angles of direction to the sun. Horizon Sensor (DG) - an optical sensor, is an infrared matrix with an optical system and detects two angles of the Earth's horizon. The angular velocity sensor (DLS) is a microelectromechanical system (MEMS) and determines the angular velocity of rotation of the SMKA along three axes. The accelerometer is a MEMS chip and detects linear accelerations of the QMS in three axes. The magnetometer is a chip with integrated or external probes, can be based on various principles of operation and determines the magnetic field strength along three axes. The temperature sensor can be, as part of one of the listed blocks, or a separate device, determines the temperature of the MO. The duplicated communication channel is network and half duplex.

Description of the device in dynamics.

After assembling the MO, the MO is calibrated. The mutual positions of all MO sensors are determined, zeros and absolute readings of the sensors are calibrated over the entire operating temperature range. The received calibration information is stored in read-only memory (ROM).

The digital computer calculator receives digital data from the sensors about three angular velocities, about three linear accelerations, about three components of the magnetic field, about two angles of direction to the Sun, about two angles of direction to the horizon, and about the temperature of the sensors. Using the readings of all sensors and calibration tables stored in the ROM, it calculates the orientation of the QMSA according to a certain algorithm and transfers it to the consumer via a duplicated communication channel.

Claims (1)

An orientation module for an ultra-small spacecraft containing a digital triaxial angular velocity sensor, a digital triaxial accelerometer, a digital triaxial magnetometer, a digital temperature sensor, a solar sensor, a horizon sensor, read-only memory and a duplicated communication channel connected to the computer, while the orientation module is designed for one printed circuit board enclosed in a housing with an optical system of the solar sensor.

Images