Busch, Stephan

Ruf, Oliver

Schilling, Klaus

English

DigitalCommons@USU

IV. AutomationThe automation of test procedures can contribute significantly to meet the needs of testing an increasing quantity of small satellites. Automation leads to time optimization and cost efficiency while enabling better utilization of test equipment and higher reliability. Standardization and unified interfaces to the test hardware are required to enable automation. Especially the automation of time-consuming repetitive tasks, such as inertial sensor tests and calibration, can lead to cost reduction by a factor of 9 [4]. The table on the left classifies which tests offer potential for automation. In addition to automation of the test procedures itself, the evaluation of test results as well as the generation of test reports and documentation can easily be automated by appropriate software.Where previously only one big satellite was integrated, verified and operated as a single unit, hundreds of small satellites require the same tasks to be performed in the future with regard to planned mega constellations and formations – while being even more cost effective. The verification process of these satellites is affected by this trend in particular and faces certain challenges:• Conventional test facilities are incapapble of efficient and economical testing of a high quantity of small satellites in a short period of time • Increasing test effort due to increasing mission requirements and miniaturization• Difficult test sensor placement due to highly integrated systems• New test equipment and methods are required to qualify distributed, cooperating systems for new applications such as autonomous feature tracking with cooperating satellites in a formation• Conventional test equipment does not provide a sufficient measuring resolution for small forces such as those occurring in attitude and orbit control actuators of small satellitesBig Data – Big Testing?Challenges and Novel Approaches for Testing Large Numbers of Small SatellitesO. Ruf, S. Busch, K. Schilling  –  Zentrum für Telematik  –  Würzburg, Germany  –  o.ruf@telematik-zentrum.de  –  SSC17-P1-36NOVEL APPROACHESReferences1. Busch, S. Robust, Flexible and Efficient Design for Miniature Satellite Systems, Uni Wuerzburg Research Notes in Robotics and Telematics, 2016, ISSN 1868-74742. Schilling K., Bangert, P., Busch S., Dombrovski, V., Haber, R., Kramer, A., Ris, D., Scharnagl, J., Tzschichholz, T., Konzeptanalyse: Testzentrum vernetzte Satelliten, 20163. Busch, S., Schilling, K., Standardization Approaches for Efficient Electrical Interfaces of CubeSats, Proceedings 4S-Conference, 20164. Curiel, Alex da Silva, et al., Production engineering a low cost video imaging constellation. 10th IAA Symposium on Small Satellites for Earth Observation, 2015AcknowledgementThis work is partially supported by the European Research Council (ERC) Advanced Grant "NetSat" under the Grant Agreement No. 320377.This contribution addresses challenges for the verification process of a large number of small satellites introduced by big data applications in the global Earth observation and communication domain. The efficient and economical verification of a high quantity of small satellites in a short period of time is not possible with conventional test facilities. Furthermore, the measuring resolution of conventional test equipment is often not sufficient for the small forces occurring on these systems. With the evaluation of test procedures, various benefits and challenges introduced by small satellites were found. The need for advanced test methods and equipment was illustrated. Several approaches to enable efficient verification have been presented and briefly discussed. The design for testability and the standardization of the electrical bus and protocols, enable the implementation of an integrated simulation, development and verification environment which offers rapid development and testing. Automation finally leads to time optimization and cost reduction and allows the economical usage of a large number of small satellites to enable big data applications.I. Design for testabilityThe challenge of time and cost efficient verification of a high quantity of small satellites in a short period of time represents a further requirement to system design.  Enabling easy access to  each subsystem for programming, testing and debugging even in a completely integrated satellite is a key-factor to achieve robustness [3]. Therefore, the testability of the satellite must be considered as a key-requirement already in the design phase in order to enable easy and effective verification.The evaluation of the testing demand indicates numerous advantages small satellites offer to test equipment. The table shows in which way small satellites facilitate different test procedures due to their low mass, small size and low power consumption. However, the low actuator forces and the highly compact integration pose challenges to conventional test facilities and create the necessity for advanced test equipment.INTRODUCTIONCHALLENGESCONCLUSIONSREFERENCES & ACKNOWLEDGEMENTNew applications in the global Earth observation and communication domain require more and more data in order to constantly improve the understanding and interconnection of our world. The data needs to be collected, processed and transmitted in high-volume at high velocity and in high variety to enable these new services.Distributed cooperating small satellites in constellations and formations offer an effective way of collecting this so-called big data. These systems promise increased temporal and spatial resolutions at significantly reduced costs and development time compared to traditional single satellites and represent a rapidly emerging market. Already the scheduled and performed launches of 474 Nano Satellites in 2017 constitute approximately 32% of all 1459 operational satellites (end of 2016).The increasing number of small satellites involved in a single mission, such as Planet, OneWeb and NetSat, offers numerous opportunities while introducing new challenges to spacecraft design, integration, verification and operations.NetSatII. Advanced test methods and equipmentBesides the need to measure smaller torques and forces, new applications require advanced verification processes and facilities to ensure reliability and robustness. With the paradigm shift towards small cooperating systems, the demand for functional testing of distributed, autonomous systems is rising. Test facilities for applications such as cooperative feature tracking barely exist and require simultaneous testing of multiple satellites. An integrated test environment for cooperative attitude control is currently being developed at ZfT.III. StandardizationStandardization is the key to economical use of small satellites in large numbers. It enables fast and reliable development, integration and verification. A standardized interface facilitates access to the system and therefore increases testability. The UNISEC electrical bus specification represents such a standardized interface that allows efficient and compact integration of the entire satellite in a plug-and-play manner while offering access to each subsystem, even when the satellite is completely integrated.The standardization of protocolls combined with the interconnection of simulation, development and verification equipment leads to a powerful environment that enables rapid development and testing of small satellites.Satellite Bus Connector• compact and robust backplane• redundant power, high-speed and low-speed digital buses• dedicated signals for reset, time sync,  deployment logic• internal debug interface (communication, programming, and debugging after integration and in-orbit)External Debug Interface• easy stand-alone operation of subsystem• debug communication (UART via USB bridge)• microcontroller programming and in-system-debugging (JTAG, SBW, SWD)• supply by USB power (5V, 3.3V, unregulated bus)Interface Control Circuit• selective bus isolation• prevents current leakage for partial power down• allows bus routing, redundancy selection controlled by OBCPower Control Circuit• controlled by OBC via redundant I²C bus• power switch• power monitoring (voltage, current)• power protection optimized for specific subsystem (over-voltage, under-voltage, over-current, i.e. latchup)Advantages due to Potential for optimization Particular challenges for testing small satellitesMeasurementsmass characteristics    geometry, dimensions and orientation  force and motion, inertia tensor    low torquethrust (electr. thrusters)   low forces, test in vacuumantenna characteristics     Functional and Performance Testsattitude and position control simulation     low forcespower generation and distribution   electromagnetic compatibility highly compact integrationEnvironmental Testsvibration      sensor placement in highly compact integrated systemstatic acceleration     shock   thermal-vacuum      sensor placement in highly compact integrated systemcommunication link    test of multiple intersatellite links (attitude)radiation low massOpportunities and challenges for test equipment [2]standard interfacesmall sizelow powertest standardsautomationRobot-assisted manufacturing and inspectionTestbed for cooperating satellites at ZfT

Big Data - Big Testing - Challenges and Novel Approaches for Testing Large Numbers of Small Satellites

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Big Data - Big Testing - Challenges and Novel Approaches for Testing Large Numbers of Small Satellites

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