The Design and Development
of an ADCS OBC for a CubeSat
By
Pieter Johannes Botma
Thesis presented in partial fulfilment of the requirements for the degree Master of Science in Engineering
at the Faculty of Engineering, Stellenbosch University
Supervisor: Prof. W.H. Steyn
Department of Electrical and Electronic Engineering
BACKGROUND 2
ADCS unit takes that same trend one step further by grouping all ADCS-related expansion boards (sensors and actuators) and having them controlled by a separate OBC. This unit can then be added easily to any CubeSat for which an ADCS is required.
Stellenbosch University’s Electronic Systems Laboratory (ESL) has already designed a horizon and sun sensor, called CubeSense, which is used in the STRaND CubeSat from
Surrey Satellite Technology Limited (SSTL) [4] and can be seen in Figure 1.1. The actuators,
OBC and ADCS algorithms are still in development.
This thesis will document the design and development of the OBC required for the ADCS unit on the 3U CubeSat. The ADCS OBC will act as the interface between the main OBC and the orientation control of the satellite. The desired attitude controller and determination estimator of the satellite can be sent to the ADCS OBC via a telecommand. This will then be interpreted and the control algorithms together with sensor data will then compute the necessary output/commands for the actuators to achieve the desired attitude. The lack of space and power on a CubeSat impose strict limits on its design, which will be discussed later in Section 2.1.
Figure 1.1: SSTL STRaND CubeSat. [4]
