Session
Technical Session XII: Software
Abstract
One of the challenges to date for operational spacecrafts is to satisfy high attitude pointing accuracy missions using picosatellites. This is due to the limitations of putting a capable spacecraft attitude control subsystem into an extremely small volume. To overcome this design constraint, Micro Electrical Mechanical subsystem (MEMS) for attitude sensors and actuators are used. However MEMS are still limited in accuracy and performance compared to conventional sensors and actuators. Given these hardware limitations, the trade off is to increase the software capabilities of the Flight Control Software (FCS) without compromising on a simple architecture concept. Astronautic Technology Sdn. Bhd. (ATSB)™ is currently developing a 10x10x30cm3 CubeSat capable of meeting missions requiring spinning or full three axis stabilization. The Attitude Determination and Control (ADCS) suite consist of a MEMS 3-axis magnetometer, three 1-axis gyroscopes, coarse sun sensing capabilities, magnetic torque coils, a pitch actuator and the well known 8051 microprocessor housing the FCS. The 8051 communicates with the master MSP430 onboard computer via a Serial Peripheral Interface (SPI). An alpha version of the FCS was developed and tested on an 8051 board. The FCS was compiled using a commercial Integrated Development Environment (IDE) and loaded directly onto the 64KB on-chip flash. The software consist of a single axis Spin control law for regulating the spin rate on any predefined axis using only magnetic torque coils. A single axis Proportional Derivative (PD) control law was also developed to manage 3-axis slew maneuvers using a mini reaction wheel and magnetic torque coils. The 8051 board was linked via RS232 to a test PC running the full spacecraft orbit and attitude simulation in real-time, i.e. Hardware-in-the-Loop (HIL). The FCS was able to detumble the CubeSat, bring it to the designed pitch spin axis, achieve 3-axis stabilization and perform 3-axis maneuvers. This simple setup allows the FCS to be designed, debugged and performance tested quickly. The FCS has been validated to meet CubeSat’s current spinning and limited 3-axis pointing mission requirements.
Presentation Slides
A Simple Multi-Mission Flight Control Software for CubeSAT
One of the challenges to date for operational spacecrafts is to satisfy high attitude pointing accuracy missions using picosatellites. This is due to the limitations of putting a capable spacecraft attitude control subsystem into an extremely small volume. To overcome this design constraint, Micro Electrical Mechanical subsystem (MEMS) for attitude sensors and actuators are used. However MEMS are still limited in accuracy and performance compared to conventional sensors and actuators. Given these hardware limitations, the trade off is to increase the software capabilities of the Flight Control Software (FCS) without compromising on a simple architecture concept. Astronautic Technology Sdn. Bhd. (ATSB)™ is currently developing a 10x10x30cm3 CubeSat capable of meeting missions requiring spinning or full three axis stabilization. The Attitude Determination and Control (ADCS) suite consist of a MEMS 3-axis magnetometer, three 1-axis gyroscopes, coarse sun sensing capabilities, magnetic torque coils, a pitch actuator and the well known 8051 microprocessor housing the FCS. The 8051 communicates with the master MSP430 onboard computer via a Serial Peripheral Interface (SPI). An alpha version of the FCS was developed and tested on an 8051 board. The FCS was compiled using a commercial Integrated Development Environment (IDE) and loaded directly onto the 64KB on-chip flash. The software consist of a single axis Spin control law for regulating the spin rate on any predefined axis using only magnetic torque coils. A single axis Proportional Derivative (PD) control law was also developed to manage 3-axis slew maneuvers using a mini reaction wheel and magnetic torque coils. The 8051 board was linked via RS232 to a test PC running the full spacecraft orbit and attitude simulation in real-time, i.e. Hardware-in-the-Loop (HIL). The FCS was able to detumble the CubeSat, bring it to the designed pitch spin axis, achieve 3-axis stabilization and perform 3-axis maneuvers. This simple setup allows the FCS to be designed, debugged and performance tested quickly. The FCS has been validated to meet CubeSat’s current spinning and limited 3-axis pointing mission requirements.
