Session
Technical Session XI: Mission Enabling Technologies 2
Abstract
Control Moment Gyroscopes (CMGs) are not often considered for use on small satellites and, as a result few small satellite missions have implemented CMGs as on-board actuators. There are many reasons for this, but mainly this is due the complexity of the mechanical and control system needed to implement an effective CMG, and also because off-the-shelf CMG systems are generally made for the larger satellite market. .CMGs offer many advantages over reaction wheel systems. When used on a small satellite, a CMG based control system can provide the ability to perform very fast slew maneuvers, making CMGs very attractive to high resolution small satellite imaging missions. The CMG described in this paper incorporates two motors; a Brushless DC Motor (BLDC) and a Stepper Motor. The BLDC provides an efficient means of driving the inertia disk to store the angular momentum, whilst the stepper motor provides precision gimbal control. In order to keep mass and power consumption low, both motors are controlled from a single FPGA. The FPGA runs all associated commutation, speed and position control for both motors and also provides the command and telemetry interface to the rest of the spacecraft. The resulting system is a compact, power efficient design that is ideal for small satellites.
Presentation Slides
A Control Moment Gyro for Dynamic Attitude Control of Small Satellites
Control Moment Gyroscopes (CMGs) are not often considered for use on small satellites and, as a result few small satellite missions have implemented CMGs as on-board actuators. There are many reasons for this, but mainly this is due the complexity of the mechanical and control system needed to implement an effective CMG, and also because off-the-shelf CMG systems are generally made for the larger satellite market. .CMGs offer many advantages over reaction wheel systems. When used on a small satellite, a CMG based control system can provide the ability to perform very fast slew maneuvers, making CMGs very attractive to high resolution small satellite imaging missions. The CMG described in this paper incorporates two motors; a Brushless DC Motor (BLDC) and a Stepper Motor. The BLDC provides an efficient means of driving the inertia disk to store the angular momentum, whilst the stepper motor provides precision gimbal control. In order to keep mass and power consumption low, both motors are controlled from a single FPGA. The FPGA runs all associated commutation, speed and position control for both motors and also provides the command and telemetry interface to the rest of the spacecraft. The resulting system is a compact, power efficient design that is ideal for small satellites.
