SWISS CUBE

Le projet SWISSCUBE du Space center de l'EPFL a pour objectif de construire un satellite qui sera mis en orbite en 2008. Différents sous projets sont proposés depuis 2006 aux étudiants de l'EPFL comme projets de semestre et de master. De plus amples informations sont disponibles sur le site du projet

Les Sous projets disponibles pour le 6ème semestre 2007

1. Simulation of the dynamic response of the SwissCube structure

The structural frame of SwissCube must be lightweight, yet robust enough to keep the satellite (including the electronics inside and the solar cells outside) intact during the vibrations and shocks of launch, and must survive repeated thermal shocks as the satellite goes from direct sunlight to being in the shadow of the earth. A structural model of the frame and attachment has already been designed and simulated by finite elements, but it needs to be updated. The purpose of this semester project is to update the structural design of the SwissCube satellite and to model the new structure by finite element in order to predict its the modal and transient dynamic response. This task includes updating the CAD & FE models of the satellite, taking into account the already designed structural attachments and adding the remaining unsolved interfaces. The main objective of this sub-project will be to compare and validate the finite element model of SwissCube with the modal & dynamic measurements performed on prototypes. The students working on this sub-project will need to collaborate closely with the group responsible for the "Vibration tests of the satellite main structural elements" task. A cooperative and coordinated work of these two groups of students is expected.

Number of students: 2

2. Vibration tests of the satellite main structural elements

Preliminary vibration tests have been performed on the main structural elements of the SwissCube satellite. However, these tests were not complete as they did not cover the full range of the required tests because of limited facility capibilities. The purpose of this project is to perform more detailed test and a modal analysis on the actual satellite prototype. Some tests will be performed at EPFL (modal analysis, sine & random vibration tests) and some tests might be performed at RUAG-Aerospace (impulse tests). The first objective of this sub-project is to carry out a detailed experimental modal & sine/random vibration analysis of the SwissCube prototype in order to provide reference values for the validation of the SwissCube design and for the calibration of the finite element model of the structure. Another aspect of this project will be to visit the potential testing facilities and determine their applicability to the project and the missing ground support equipment. The students will also write the test definition and procedure according to the imposed design, quality and safety standards. The students working on this sub-project will need to collaborate closely with the group responsible for the "Simulation of the dynamic response of the SwissCube structure" task. A cooperative and coordinated work of these two groups of students is expected.

Contact:  J. Cugnoni, LMAF
Number of students: 2

3. Design of the Thermal Subsystem

The EPFL-LTCM is responsible for developing the Thermal Subsystem on the SwissCube satellite. The thermal subsystem contributes to the satellite design in terms of geometry, implementation of insulating materials, implementation of batteries and electronic components, implementation of the science instruments, and includes passive and if necessary active thermal devices to control the satellite's thermal states. The purpose of this project is to perform numerical analysis of the Printed Circuit Boards (PCBs) and determine if the actual design is acceptable from a thermal standpoint. By numerical simulations, the student will predict the temperature distribution in the PCB. He/she will determine the thermal constraints inside the structure (location of hot spots) and the temperature fluctuations of the elements (compared to the limits). By experimental measurements, he/she will validate the numerical results.

Contact:  Thierry Ursenbacher, LTCM
Number of students: 3

4. Assembly procedure and cabling plan of the satellite

One of the challenges of SwissCube is its size: 10x10x10 cm3. Although the design of the configuration inside the satellite was thought of from the beginning, some issues remain to be solved. This project will consist of thinking through and finding solutions for the overall assembly process. This will require that the student understand the subsystems, their functionalities and the test flow. That also include coming up with a smart solution for routing all the cables inside the satellite and making sure all connections can efficiently be done before the satellite is completely integrated. The final steps in this project will be to implement the procedure and test it on the second prototype of the satellite.

Number of students: 2

5. SwissCube Magneto-torquers implementation and test

During last semester project, the hardware (sensors, actuators and controller) for the SwissCube attitude determination and control system (ADCS) has been selected, and preliminary tests have been made. The goal of this project is to finalize and test the ADCS actuators, namely the magneto-torquers: test driver stage and the coils themselves, develop a 3D simulation model, build the test bench and implement the final design.

Number of students:    2

6. Sun Sensor characterization and calibration

The attitude determination of the SwissCube satellite relies in part on sun sensors on each face to determine the angle to the sun. The Danish Technical University has fabricated micro-machined sun sensors, and has provided us with samples. A printed circuit board has been fabricated to operate the sun sensors. The student will build an automated test stand to simulate sunlight impinging the sun sensor wit ha variable angle, and then use this test stand to characterize the performance of the DTU sun sensors in view of integrating them into SwissCube.

Number of students:    2

7. Antenna Deployment System for the SwissCube Satellite

The data exchanged between the SwissCube and the earth stations are transmitted on amateur radio frequencies. The antenna on board will have a length up to 1 m. The final size will be chosen accordingly to the used radio frequency. The satellite must carry a fail-proof, small and lightweight antenna deployment mechanism which will be activated once the system is in orbit. At the same time, aerospace compatibility must be ensured. This work is the result of a preceding semester project that showed that the best and easiest solution is to use a flexible antenna, rolled up during the whole launch phase, which deploys using its own spring effect. A first prototype has already been built, which permitted to show the feasibility but also some weaknesses of this solution. This project consists of three different phases. In the first part of the work, the student will have to gain the basic knowledge about the SwissCube technical details and study the preceding semester project. After this study, materials and dimensions of the different parts of the system must be chosen according to detailed mechanical, dynamical and electromagnetic analysis and a prototype will be built and tested to validate proper behavior. Third, a dynamics analysis shall be performed to characterize the deployment behavior. Tests are also possible in this third phase.
This project requires the cooperation with the students working on other aspects of the SwissCube, such as the communication subsystem or the satellite structural design. This collaboration will be achieved by regular meetings.

Point of Contact: Tomasz Jodlowski,LCSM
Number of students: 2

8. Mechanical characterization and finite element simulation of electronic packages

Electronic packages (CPUs & IC chips mounted on PCBs) are complex multimaterial structural systems operating under dynamic thermal and mechanical loading conditions. For space applications, they must survive the launch environment and harsh thermal cycling. The solder joints may not only be electrical inter-connections but may also play a significant role in the mechanical stability of the PCBs. Due to possible scale effects, the mechanical properties of the constituents should be determined at the same characteristic size as the real components or even preferably directly in-situ in a real product. The aim of this project is to further develop an inverse identification method based on both finite element modeling and optical strain & temperature measurements to determine in-situ the properties of the soldering alloys. The student will participate in the design of the specimens, the development of the experimental procedure for testing selected joint designs subjected to thermal and mechanical solicitations and correlate the results with adequate finite element models.

Contact: Joël Cugnoni, Matteo Galli, LMAF