Design of a control moment gyroscope for small satellites

Abstract

The primary aim of this project is to design a Control Moment Gyroscope (CMG) prototype for single axis control of an agile small satellite. The design should be small, compact and lightweight. Miniature motors and aluminum material were used to reduce the size and weight of the prototype. The overall prototype has a dimension of 12.5 x 12.5 x 12.5 cm and weighs 1.6 kg, which is significantly smaller and lighter than conventional CMG.

Testing of the prototype design was conducted to fine-tune the controller gain values in order to achieve optimal motor responses. Furthermore, gimbal rate testing was conducted to validate the frictional losses within the gearing system. The results indicated that frictional losses were minimal. The controller was also capable of executing gimbal angle command sequence specified by the user.

Simulation results were obtained based on a small satellite mathematical model that used CMG actuation. Simulation results indicated that the satellite was capable of high slew rate (3o/s) using CMG actuators. Experimentation using ECP model 750 CMG was conducted to validate the mathematical model. Prior to experimentation, the setup was integrated to SIMULINK environment to enhance the usability of the data collected. Experimental results obtained were unable to fully validate the model due to the effect of friction.

Future testing of the prototype design on an air-bearing table will be conducted to validate the mathematical model as well as the feasibility of the CMG design.