Abstract : In the current scenario, weather monitoring is playing a very significant role. Every day around 800 satellites (Radiosonde) are being launched for weather sampling globally. The objective of this project is to design and develop ground station software system along with a cost effective small satellite. The software will be developed using JAVA as front end and SQL as backend; small satellite will be designed and developed from off shelf-materials and open source on board computer. The small satellite will be launched by a rocket which will carry sensor array to transmit information about the atmospheric pressure, temperature, humidity, altitude, Global Position System (GPS) and wind speed by means of small sensors, and Transistor-Transistor Logic (TTL) wireless data transmission.The collected data are preprocessed used data mining techniques using orange tool and results are displayed in a scatterplot .
Keywords ‘ GUI, Small Satellite, Ground Station, Sensors, GPS.
In the view of current technological developments Small Satellites are playing a very important role, they have been largely developed for education, earth observation and constellation operations. Over the last 50 years, more than 860 microsatellites (10’100 kg), 680 nanosatellites (1’10 kg), and 38 picosatellites (0.1’1 kg) have been launched worldwide. Small satellites have recorded data on the terrestrial and space environment near the moon and Earth, helped in the search for planets on other star systems, and demonstrated various telecommunications systems that we enjoy today. These satellites have served as test beds for the development of new space technologies, and as hands-on educational tools for countless students, scientists, and engineers. The architecture of small satellites being far simpler than large, long life spacecraft built by governmental space agencies provides room for commercial entities to pitch in for their construction. There is a large scope of using Commercial off the Shelf (COTS) components
within such a small spacecraft, given that their designed lifetime is low. They can also be used as excellent technology demonstrators for large missions.
The interest is not just for non-space countries but also has grown to attract universities,commercial entities to experiment in space. As we move ahead, the trend is moving towards making it much simpler for schools to gain access to space by simplified technology building. This change has the potential of transforming space technology within a very short period, considering the context of the history of satellite development. The research in small satellites has moved from using them in Low Earth Orbit (LEO) to extrapolating their uses in interplanetary travel. One of the key supporters for this movement within space is the United Nations Office for Outer Space Affairs (UNOOSA). UNOOSA conducts the Small Satellite Symposium every year since 2009. There has also been a substantial rise in the number of companies that are building small satellite for privately offered space based services including education, identification of ships, remote sensing, disaster management, etc.Small satellite has given an opportunity for non-space countries to gain access to space technology for the first time. The reason being their low cost, development time and mass, small satellites are particularly attractive since they are ‘affordable’. There shall be no surprises in the near future, if more and more developing countries, groups from the academic world, small teams of space enthusiasts develop their own space mission based on small satellites as an entrepreneur effort for space based services, which is otherwise provided by governmental agencies.
II. SYSTEM OVERVIEW
Mission definition is concluded as follows.
‘ Base Mission:The base missions are
listed as the following, with priority order;
(1) to read the values obtained via sensors,
(2) to design the interface of the ground station, (3) to transmit the data properly to the ground station,
(4) to record the data into memory unit.
(5)to process the data using data mining techniques.
‘ Side Missions: The following missions
are listed as Optional ;
(1) to record a video of descent moment using camera sensor,
(2) to designate the point of landing using a GPS module.
B. Small satellite and Subsytems
The subsystems of the Small satellite are developed under three separate topics.
Mechanical design’s main mission is
to provide a safe landing, protect the carrying all of the electrical and mechanical components safely and, be a safeguard against ‘g’ forces. In this regard our design is an innovative, robust, and functional solution. The mass is limited with ??500 gms.
Mechanical design consists of two parts as depicted in Fig.
The parachute is used for safe landing of the on-board computer. It is compulsory to construct a chasis that is capable of providing the protection of the components from the impact during landing. Inorder to provide protection a reliable material has to be choosen.
Acrylics material is choosen for building the chasis, since it has high resistance to impact and protect the on-board components.
Figure1.Design of a small satellite chasis
The container is made of aluminium foil to protect the internal components since the material is light and highly resistance to wear and tear.
Electrical architecture is summed up in two divisions as follows.
The CanSat needs electrical system for communication and the internal components . In choosing electrical system, we considered requirements of mission. The electrical architecture includes sensors, microcontroller, battery, memory card, and other circuitry. We need to power up enough power to other subsystems. We choose Li-Ion batteries. The batteries connect to the sensors and the microcontroller. So, we got 5 V voltage level and a 5000 mAh current capacitiy. The sensors, microcontroller, distance sensor, camera, GPS, and the memory card supplied by 5 V. All sensors and transmitter/receiver modules are supported by 3.3 V.
Figure2.Electrical architecture block diagram and ground station
The high-performance, low-power Atmel 8-bit AVR RISC-based microcontroller combines 32KB of programmable flash memory, 2KB SRAM, 1KB EEPROM, an 8-channel 10-bit A/D converter, and a JTAG interface for on-chip debugging. The device supports throughput of 16 MIPS at 16 MHz and operates between 4.5-5.5 volts. By executing instructions in a single clock cycle, the device achieves throughputs approaching 1 MIPS per MHz, balancing power consumption and processing speed. The sensor shield includes accelerometer,gyroscope,barometer,temperatue sensor ,ATMEGA32 microcontroller. The GPS and the memory card can be easily integrated with this configuration. For programming the microcontroller,Audrino IDE is used through which the program is compiled and uploaded to the microcontroller.The output of the microcontroller can be viewed throught the serial monitor of the IDE.
3. Telemetry and Ground Station:
Telecommunication part of the system consists of a TTL network, which is peer to peer model communication type. Network is set up with one communication module attached to the satellite and another module that is connected to the terminal in ground station. Module on satellite receives all the sampled data via serial interface from microcontroller, and send it to the module on ground station via radio waves. Both modules work on 2.4 GHz frequency. Data rate for communication is 250 kbps including headers and acknowledgement overhead. Communication module on ground station acts as a relay, and transmits all the received data from remote module to the terminal via serial USB interface. Serial data rate for both modules is 9600 bps without parity and handshaking. On ground station terminal, a JAVA application is written specifically for this system. All the received data is prompted to the user in a grid view. Specific data types of temperature, voltage, and altitude are plotted to charts, except GPS data. For GPS data, Google Earth’ is used for plotting the real-time coordination of the satellite. Ground station application also shows RSSI (Received Signal Strength Indicator)
information, which shows the quality of the received signal.
4. Datamining Using K-means Algorithm(Orange Tool)
K-means is a cluster based algorithm used for mining of the valid data from the data collected from the small satellite. It is a cluster based algorithm used for clustering of the respective data based on the value of the K given to the algorithm. The value of the K should be chosen in such a way so that it suits the amount of the data to be clustered. When the data is given to the algorithm random points are selected based on the k value given. The Euclidean distance between the nearby points calculated and the particular nearest centroid is taken as the master point of that cluster. The particular values that are needed to be clustered are then imported using the sql query option in the tool.
After the data is loaded the k-means algorithm is executed in order to find the master points(centroids) and plotted in scatterplot.
5. Google Earth used to locate the small satellite
The coordinates of the path of the small satellite stored in the database is retrieved using the java application . The retrieved coordinates are converted into a kml file format since the google earth is able to understand the kml format of the coordinates for plotting the particular location.
After the kml file is generated the file is given as input to the google earth using drag and drop option. The Google earth takes the kml file as input and plots the respective coordinates to be identified and the location of the last coordinate gives the exact location of the landing of the small satellite and the small satellite is retrieved and deploy for future experiments.
III. SYSTEM ANALYSIS
During the launching of the satellite all the components have to be protected. In order to ensure the required strength of the system, Structral analysis – for material to be withstand its weight in parachute have to be made.This structural testing and analysis is done using the Ansys software . A CAD model is developed for this purpose using the catia V5 software.
Figure4.Structural analysis using ansys
Figure5. MeshGeometry in Ansys Software
The ground station software system developed using java and the data stored in the oracle database.
IV.RESULTS AND DISCUSSION
The Graph of the atmospheric values that were plotted shows the change in the temperature , pressure and humidity.
Figure6.Graphical representation of Temperature Humidity and Pressure Values
Figure7.Serial Monitor Collecting Data
Figure 8 . java application collecting data and storing in the database
Figure 9 .The values stored in the database show in the GUI of the oracle database explorer
The Orange tool showing the way the data is get processd in the later steps and the final output is displayed in the scatterplot .
Figure10.Schematic view of the data loading and clustering and result status
Figure11.The diagram shows the data clustered and the along with their respective clusters
Figure12. The entire data and its respective cluster is shown in different color
Figure13.The respective data mined values are specifically shown in this figure
Figure14.The respective coordinates are plotted in the google earth
Figure15.The particular coordinate can be zoomed and the exact location of the satellite can be identified
The development of the Small Satellite involves steps such as designing a CAD model for the external body of the satellite, performing design iterations of the CAD model, Fabrication of sensors with the Arduino board and Development of sketch for the on-board computer. Developing an algorithm for the Graphical User Interface and interfacing the on-board computer with GUI. Initially, the CAD model of the body of the Satellite has been designed, stress analysis has been performed and the sketch for the Arduino Controller Board is developed. The fabrication of the electronic components is performed along with the Controller Board. The GUI based on java Platform and interfacing the On-Board Computer along with the GUI is developed. The exact value is then data mined and shown in scatterplot diagram and after the landing the exact location of the satellite can be identified using the coordinates plotted in google earth.
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Competition, Recent Advances in Space Technologies (RAST), 2013 6th International Conference
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