Magnetic Control for Detumbling of Satellites: A Tutorial

The standard purely magnetic attitude control system utilizes three magnetic actuators to control the spacecraft attitude about three principal axes. Although these actuators are usually cheaper than momentum wheel actuators, they are still costly to develop. In addition, having more actuators increases the complexity of the control. This paper presents a controller that reduces the number of magnetorquers required for attitude control from the conventional 3-configuration to only two which reduces weight and volume requirements as well decreasing the complexity of the system. This encourages the use of a momentum wheel to ultimately create higher accuracy systems such as pitch bias momentum systems. The controller is demonstrated to be able to successfully damp the angular velocity of the spacecraft in two of the axes with a non-zero constant pitch rate which opens up the opportunity to use a pitch momentum wheel to stabilize the spacecraft and introduce gyroscopic stability.