Design and Structural Analysis of a Control Moment Gyroscope (CMG) Actuator for CubeSats

Abstract

Following a global trend towards miniaturization, the population of nano- and micro-satellite continues to increase. CubeSats are standardized small size satellites based on 10 × 10 × 10 cm cube modules (1U) and are becoming sophisticated platforms despite their very small size. This paper details the design and the structural analysis of a Control Moment Gyroscope (CMG) actuator for agile CubeSats with a physical size up to 12U, which require high torque actuators. CMGs have inherited torque amplification capabilities and the recent advances in motor miniaturization make them ideal candidates for small satellite missions with slew rate requirements. The system’s requirements are derived based on conceptual agility requirements for an agile (highly maneuverable) CubeSat which needs to achieve a 90° maneuver in 90 s. With specific cost, mass and volume requirements, the proposed CMG design is based on some of the smallest available off-the-shelf electric motors and uses a light aluminum casing design. The proposed design uses stepper motors for the gimbal mechanism as a low cost, compact and low power solution, contributing to an overall low mass of the full CMG cluster. Static and dynamic analyses were performed to assess the mechanical integrity of the system for launch loads. Apart from a necessary custom control electronic board, the complete mechanical assembly has been designed including electrical hardware. Analyses demonstrate that the overall stress levels acting on the system are manageable by the CMG design. Bolted joints are critical and should be studied independently as the chosen model created singularities around these areas. Each individual CMG of the designed pyramidal cluster is shown to weigh about 35 g. Using the proposed CMG design with a customized avionics board, the complete CMG system is shown to weigh 250 g and occupies slightly more than ½U volume for a CubeSat, indicating the feasibility of CMGs for agile CubeSats.

Investigating the use of 3D printed soft magnetic PEEK‐based composite for space compliant electrical motors

“…The electromagnetic FE simulations (Table 10), in fact, reported output torques in line with some low power aerospace applications, such as micro-actuators, pointing devices for small antennas, and mini control moment gyroscope (mini CMGs). 66,67 The transversal configuration for the electric coils (Figure 14) results in an output torque three times higher than that of the planar configuration (Figure 13). This effect is directly related to the larger number of conductors per sector in the transversal configuration that optimizes the use of the available volume.…”

Event-Triggered Attitude-Tracking Control for a Cableless Non-Contact Close-Proximity Formation Satellite

“…Special attention was paid to the fact that there were no cables between the two modules, avoiding the non-contact interface coupling effects on the attitude control performance of the PM. In addition, the NCLA adopted in this architecture was a linear actuator with direct current drive, which had a higher control accuracy than the control moment gyro (CMG) [30,31].…”

Design of quaternion-based synergetic attitude control for microsatellite using control moment gyros

“…To be able to generate torque in any direction, CMGs are used as a group which is formed in a specific configuration. A pyramidal configuration is commonly selected for many large and small satellite applications [2]. Since a group of CMGs can generate a larger output torque compared to other kinds of actuators, it is considered a suitable actuator for the microsatellite which has a large body and mostly for missions that require a rapid response.…”