Nanosatellites

4 I-2cAttitude Control and Determination

Willem H. Steyn¹, and Vaios J. Lappas²

¹Department of Electrical & Electronic Engineering, University of Stellenbosch, South Africa

²Applied Mechanics Lab, Department of Mechanical Engineering and Aeronautics, University of Patras, Greece

4.1 Introduction

The use of active attitude control and determination on nanosatellites is growing, but still less than 25% of all orbiting nanosatellites are three-axis stabilized. In a CubeSat Attitude Determination and Control System (ADCS) survey in 2006 by École Polytechnique Fédérale de Lausanne (EPFL) Space Center, out of 18 CubeSats only nine (50%) used active magnetic control, seven used passive magnetic control, and two had no control. Only four CubeSats could be stabilized to a pointing attitude: one using a momentum wheel, one was spin-stabilized, and two used a gravity-gradient boom. In a more recent 2014 review [1] of 42 small satellites (excluding CubeSats) from 6.5 to 94 kg launch mass over the past 25 years, 5% had no control, 19% had only passive control, and 76% had some form of active control. The list of ADCS sensors comprised of: magnetometers (90%), sun sensors (80%), earth sensors (10%), Global Positioning System (GPS) (33%), rate sensors (40%), and star trackers (35%). The list of ADCS actuators comprised of: permanent magnets (20%), magnetic torques (80%), momentum wheels (8%), reaction wheels (40%), propulsion systems (18%), gravity-gradient booms (15%), and control moment ...