Astro- und Feinwerktechnik Adlershof GmbHACS

Test Stand

Testing the attitude control system (ACS) for a micro satellite is one of the most complex steps in the verification process. Software-in-the-loop simulations (SILS) and hard-ware-in the-loop simulations (HILS) have long been the established test methods, but the ideal solution is a genuine end-to-end test on a test stand designed for that purpose. Based on the experience gained from various satellite projects, Astro- und Feinwerktechnik Adlershof GmbH has developed such a facility.

ACS Test Stand

Key features: • Free rotation about the vertical axis,

20° rotation about the two horizontal axes

• Air bearing gap of a few µm for very low disturbance torques

• Safety mechanism for test stand pressure loss or power failure

• Moment of inertia from 3 kgm² to 20 kgm²

• Test object weight up to 100 kg (depends on the moment of inertia)

• Integrated electronic Center-of-Gravity calibration (via WLAN)

• Power source and distribution (600 Wh minimum, typical voltage available at various DC/DC outputs)

• Magnetic field simulation up to 210,000 nT in all three axes

• Sun simulation with 50,000 lux • Software to control the test bed com-

ponents and the simulation, e.g. for the orbit simulation a SGP4 model is used

With this test stand a complete end-to-end verification of ACS systems for mini and micro satellites can be carried out with great pointing accuracy, including long duration testing. This test stand is an ideal extension of software-in-the-loop and hardware-in-the-loop tests with regard to the special design and test requirements that mini and micro satel-lites inherit.

1 Helmholtz coil system for magnetic field simulation 2 Sun simulation with adjustment and positioning mechanism

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Magnetic field simulation The simulation of the Earth’s magnetic field generates a maximum field of 210,000 nT with a accuracy of 1%. The magnetic field simulation bases on an IGRF model and uses the satellite posi-tion to generate the magnetic vector for any orbit position. Sun simulation Solar simulation with 50,000 lux from any position in upper sphere of test stand. Air Bearing Table By using a high-precision air bearing and contact-free calibration of the air gap, the disturbance forces along all three axes are low and comparable to in-orbit dis-turbance torques- of lower earth orbits. Additionally, the air bearing table is equipped with a safety mechanism to protect the air bearing itself.

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Electric power supply on the adapter plate, including DC/DC converter box 1 rechargeable batteries | 2 DC/DC converter box | 3 WLAN command interface 4 air-gap monitor and safety-mechanism control

Platform The platform comprises a mounting plate with a mechanical interface for the test object, a CoG calibration system, the power supply and different support equipments. Reference system The external reference system based on 3D motion tracking can be used to mea-sure the attitude of the platform and the unit under test independently from the simulation. The attitude of the platform will be visualized in the test bed control software and generates inputs for the optional Star Simulation. Additionally, the attitude can be logged together with the simulation data.

GNSS Simulation The GNSS simulation consists of hard-ware and a software component as well as the remote connection to the test bed control software. The GNSS simulator can supports all current GNSS signals, including GPS, GLONASS, Galileo, Bei-Dou-2, WAAS, EGNOS, MSAS, GAGAN, SDCM, QZSS and IRNSS. Star Simulation This extension to the ACS Test Bed allows the simulation of sensor inputs for a star tracker and the integration of a star tracker into the ACS hardware-in-the-loop testing environment. The Star Simulator can provide signals for up to 4 optical heads in the same time. The system simulates stars, plan-ets, sun, stray light and protons. Nano satellite Test Bed The Nano Satellite Test Bed is an exten-sion of the testable satellite range to smaller satellites up to 10 kg. The Nano Satellite Test Bed is equipped with a manual COG calibration.

Astro- und Feinwerktechnik Adlershof GmbH

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Albert-Einstein-Str.12; 12489 Berlin; Germany phone: +49-30-6392-1000 fax: +49-30-6392-1002 www.astrofein.com

The Berliner Ring Autobahn (A10) Proceed to the Schönefelder Kreuz interchange, then take the A113 leading north towards Schönefeld Airport. Take the Treptow exit and follow the B 96a towards Zentrum (the city center). At the Adlershof S-Bahn station (inner-city train lines), turn left on Rudower Chaussee. The City Freeway (Stadtauto-bahn) Follow the Schönefeld Airport signs to the Adlershof exit. Alexanderplatz (in the middle of town) Take B 96a in the direction of Schönefeld Airport. At the Adlers-hof S-Bahn station (inner-city train lines) turn left on Rudower Chaussee.D

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