Sponsored by AFOSR and AFRL
Project Participants: Mark L. Psiaki (PI) and Moshe Guelman
A new generation of spacecraft attitude controllers is being designed and flight tested, controllers that use only magnetic torque rods for actuation and that are designed using techniques for periodically time-varying systems. This research is being conducted in order to develop more reliable, lower-weight, lower-cost attitude controllers for small spacecraft that are components of large constellations. A second goal is to gain practical experience with controllers for periodic time-varying systems and to advance the state of the art of control-law design for such systems. The attractiveness of using only magnetic actuation is that torque rods are light-weight and more reliable than wheels. The challenges of using only magnetic actuation are that the resulting system is periodically time-varying and that it is under-actuated. The latter challenge makes it difficult to achieve high levels of pointing accuracy with such a system. In order to meet these challenges, the investigators are using recently developed Linear Quadratic Regulator-based control techniques for periodic systems. These techniques are being used to overcome the challenges posed by under actuation and by the significant levels of uncertainty that are associated with models of the Earth's magnetic field.
An important feature of the research is that the new controllers are being flight tested. The Technion's TechSAT Spacecraft has all of the components that are necessary for trying out the new control laws. It is being used to test the new controllers' stabilization, disturbance rejection, maneuvering, and large-angle capture properties. Such tests aim to prove the new controllers' efficacy in a convincing way, so that future spacecraft project managers can confidently decide to use them. Also, successful application to a significant real-world problem will showcase the new theoretical capabilities to design controllers for general periodic systems.
A second application case for the project is to the TechSat 21 Program. This project is using the TechSat 21 attitude control problem as one of its primary application examples, and the results will be transmitted to the TechSat 21 program in support of that mission.
Last updated 9 Feb. 2001