My research involves developing techniques to 3D print electric motors and electronics. This goes beyond the usual 3D printed structures - structures don’t do anything. To do things, we need motors and electronics to control those motors.

3D Printing of Motors and Electronics

Alex Ellery | Carleton University

Carleton University Prof. Alex Ellery has no problem dreaming that big. Ellery, an associate professor in the Department of Mechanical and Aerospace Engineering who is the Canada Research Chair in Space Robotics and Space Technology, is working on the evolution of 3D printers that could one day help tackle everything from global warming to the strain on our energy resources.

 

Explain how you think space technology can alleviate climate change on Earth?

The Earth has finite resources while outer space has effectively infinite resources of materials and energy. For example, solar energy on the Earth’s surface (as captured by your rooftop solar panel) is diminished by its passage through the Earth’s atmosphere. In space of course, it is not. If that solar energy could be captured in space and then transmitted to Earth without loss, this would be more efficient. In fact, it can, by transmitting solar energy as radio waves that can pass through the Earth’s atmosphere unabated to be captured by a series of metal tubes on the ground. This method of energy generation is clean and effectively removes the entire energy generation industry from the Earth’s biosphere into space.

 

 

Why are self-replicating machines necessary?

The biggest problem for any kind of space mission is the expense of getting out there from the Earth’s surface. Why not bypass that problem altogether? Self-replication is a powerful means for getting a big bang for your buck – imagine if you could launch one factory, like a FabLab, to the Moon or other location, and it could make copies of itself? If supplied with enough resources, it could breed like a rabbit population – 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8126, 16384, 32768, 65536, 131072, 262144, 524288, 1048576… So within just 20 doublings, we have over a million such factories. Once the required number of factories is constructed, they could be re-programmed to manufacture something more useful. Let’s say, each factory manufactures 1000 refractor lenses – a billion such lenses could be emplaced between the Earth and the sun to deflect a small proportion of solar radiation from Earth to offset global warming. Unlike terrestrial geoengineering proposals, such space-based geoengineering is completely reversible. This would be impossible without self-replication technology.

 

How feasible is it to use just Moon stuff to make useful stuff?

The Moon shares some of the geological characteristics of the Earth – indeed, it was formed by a Mars-sized asteroid impacting the early Earth billions of years ago. The Moon is quite rich in useful materials – it has soil which can be formed into glass, gases in that soil including water and carbon compounds that can be made into plastics and oils, ilmenite minerals from which iron can be extracted, and buried nickel-iron meteorites which are host to lots of useful stuff like iron, nickel, cobalt, tungsten and selenium. Using a restricted subset of such materials, we can construct structures of various shapes and sizes, electromagnetic devices, electrically conducting wires, electrical insulation, optical and photosensitive components, etc. There is one thing missing though – salt! Some of the manufacturing processes require recycled reagents based on sodium and chlorine which requires transport from Earth – a just little goes a long way. This apparent disadvantage can be turned to advantage however. It provides a means of controlling and terminating the replication process through the denial of salt – a “salt contingency”.  

 

Where does 3D printing come in?

Once we’ve extracted our desired materials from the Moon, we can use 3D printing to make them into useful structures and other devices. 3D printing covers a wide range of techniques – most people are familiar with 3D printers that extrude heated plastic onto a work platform layer by layer. However, metals can also be printed using lasers or electron beams to sinter or melt them to create the layering characteristic of 3D printing. Ceramic may be 3D printed using concentrated solar energy using lenses. Furthermore, 3D printing is very flexible in that it can manufacture shapes that cannot be manufactured in alternative ways. There are of course problems to deal with, especially when dealing with metals, such as surface finish but there are methods for coping with such problems.  

 

What exactly are you doing to try to achieve this?

My research involves developing techniques to 3D print electric motors and electronics. This goes beyond the usual 3D printed structures - structures don’t do anything. To do things, we need motors and electronics to control those motors. Rather than printing solid state electronics, we are investigating the printing of vacuum tube devices. We are also adopting a new approach to computers using neural networks built in hardware. If we can print these two devices (motors and vacuum tubes), we can 3D print almost anything. This includes mechanisms, robots and 3D printers – hence, self-replication.

 

Are other scientists or technology professionals on board with these ideas?

Self-replication technology has been an idea for several decades but only recently has it become potentially achievable. It is still considered to be a technology for the far future so its significance is widely under-appreciated. Nevertheless, there is a small cadre of visionary scientists and engineers who do understand its significance. One of my goals is to spread the notion that it is not a technology of the far future – it is a technology for today. The hobbyist RepRap 3D printer is a step in that direction – I am taking it several steps further.  

 

How did you think of this idea?

I came across the idea of self-replicating machines studying for my master’s degree in astronomy. There had been a heated scientific debate – the Sagan-Tipler debate - about whether extraterrestrial intelligence exists. The argument centred on the notion that if extraterrestrial intelligent beings existed, they could, for whatever reason, explore the Galaxy at low cost by employing self-replicating machines. So where are they? There is no evidence of such machines. I found this argument so compelling, I was converted from believer to skeptic, and decided to study for a PhD in space robotics to learn the skills to build such a machine. Now, 25 years later, with the advent of 3D printing, I am embarking on this goal.  

 

What’s the next step?

There are many steps! The first is to demonstrate that an electric motor can be printed. This prototype must then be developed and matured into a usable form. Then it must be integrated into a working 3D printer model. At the same time, we have been developing our neural network hardware. We must also demonstrate that electrical components can be 3D printed – resistors, capacitors, inductors, diodes and vacuum tubes – and assembled into neural network circuits.

 

About Alex Ellery

Prof Alex Ellery is a Canada Research Chair in Space Robotics and Space Technology at Carleton University. He conducts research into planetary rovers, satellite servicing robots, and robotic planetary exploration. Formerly at the world-famous Surrey Space Centre in the UK, Alex joined Carleton’s Department of Mechanical & Aerospace Engineering in 2007. He has a BSc (Hons) in Physics, MSc in Astronomy and PhD in Astronautics & Space Engineering, all from UK universities. He has been mulling about self-replicating machines for 25 years (he was introduced to the concept as an MSc astronomy student in the context of the Sagan-Tipler debate on extraterrestrial intelligence – this convinced him to do his PhD in space robotics) but only recently have a series of technological advances (including 3D printing) come together to make construction of such a machine possible.

 

 


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