Satellite positioning using miniature dc motors
04 April 2013
Scottish based business Clyde Space, is exploring new and exciting opportunities using Nano-satellites controlled by brushless dc motors. The company's UKube-1 is the UK’s first CubeSat mission and Scotland’s first satellite. It was launched via a Russian Soyuz-2 rocket last month from the Baikonur Cosmodrone in Kazakhstan.
Payloads for the UKube-1 include the first GPS device aimed at measuring plasmaspheric space weather; a camera to take images of the Earth and test the effect of radiation on space hardware using a new generation of imaging sensor; an experiment to demonstrate the feasibility of using cosmic radiation to improve the security of communications satellites, and to flight test lower cost electronic systems. It will also carry five experiments that UK students and the public can interact with and an outreach programme that also allows schoolchildren to interact with the spacecraft.
Nano-satellites, or CubeSat’s, are miniaturised satellites used for space research and exploration and are generally 100mm cubes with a mass of less than 1kg. The design was conceived to enable the construction of low-cost, workable satellites for research purposes.
Clyde Space has been working with maxon motor to improve the future CubeSat attitude control. Such improvements would extend the use of these vehicles to applications such as earth observation with high resolution cameras, the transmission of high bandwidth data, space science, astronomy and verification of new technologies in orbit.
Clyde Space has been working alongside maxon motor’s UK operation to develop a full three-axis attitude control system based on ‘torque reaction positioning’. This system uses a reaction/momentum flywheel, driven by a maxon brushless dc motor.
By changing the speed of the flywheel a reactionary torque is applied to rotate the CubeSat around an axis and by maintaining the rotation, the CubeSat is stablised. Several reaction/momentum wheels are used to provide the full three-axis attitude control and stability.
Clyde needed to keep the costs in check and so it chose a standard off-the-shelf, 20mm-diameter brushless dc motor. maxon modified the product to meet the application environment, supplied and fitted the flywheel, and dynamically balanced the complete assembly. Clyde Space‘s CEO Craig Clark takes up the story:
“The involvement of maxon motor in this project has been fundamental in developing the torque reaction drive. We have worked with the company to ensure the brushless dc motors survive the high vibration and shock load challenges of rocket launches and the high thermal cycling and radiation levels experienced in orbit. It is refreshing to see a customised off the shelf product meet this demanding environment rather than having to use a bespoke designed motor with all its attendant cost implications.”
maxon engineer, Paul Williams says that by starting with a standard product and then customising it, Clyde Space has achieved the most cost effective solution to its satellite attitude control problem.
“Understanding the application is paramount to finding the right solution,” he says. “We have a lot of experience in space, having already been a part of the Mars missions, and it is exciting to see the use of our products in this pioneering arena.”
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