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MacGyvering with Madox

Mechatronic engineer John Chan shares his hacks from his iPhone-contolled mecanum rover

With a background in mechatronics, John Chan works as an ICT engineer in New South Wales, Australia, designing computer systems for trains. In his free time, Chan chronicles his diversions under the handle Madox on his blog,

These "engineering perversions" -- as he calls them -- are solutions to almost any "odd, weird, but cool and fun" engineering problem that pops into his head, like a motorized coin shooter, a new computerized speedometer for his Mazda, or a floating camera.

"The blog has been a means to share ideas and to teach others about engineering," Chan says. Particularly with his recent iPhone-controlled rover, Chan is trying to be more instructive in the details, so that his online followers can build their own versions. "That is the nice answer. A lot of the time the blog is just to document things I'll probably have to do over, but I'll forget how I did them the first time."

Smart phones and crabs

Madox's iPhone-controlled rover is almost exactly what the name implies. Except in his videos, Chan is using a look-alike Android phone. But the commands could come from an iPhone just as easily. "The remote controller was designed as a web interface over WiFi. This means that almost any modern 'gadget' with WiFi could control it, including Android phones, iPhones, iPads, iPods, Windows phones, and even your humble, old-fashioned laptop." Chan's rover robotic platform is a cheap, easily constructed, and has "interesting bits like Mecanum wheels that can move sideways like a crab."

YouTube video

Mecanum wheels are the spiral-shaped rollers Chan modeled in Alibre Design and fabbed on his low-cost FDM 3D printer called "Up!" This method of locomotion is the ideal compliment for an iPhone-type touchscreen that picks up fingertip strokes at any angle. The rover does not have a turning radius like a car. Instead, it moves in any 2D direction immediately.

"I was reading online how some people were stuck when drawing the profile for the rollers, so I decided to try figure it out for myself," recalls Chan. "The trick was quite simply that the wheel should be circular when viewed on the side with the rollers attached, and it was surprisingly easy to model with Alibre Design."

The Madox blog, as well as Chan's profile, give hints to other robot-builders how to adopt the Macanum wheels and WiFi interfaces for their own projects. The WiFi and USB components, for example, were Chan's hack of a Chumby alarm clock, which serves the purpose of a programmable onboard Linux PC.

Following your own perversions

As a primarily Linux user, Chan admits that Alibre Design is probably the only Windows-based software he has purchased in years. For the MacGyver-ing of hacked electronics into straightforward mechanical assemblies, Alibre Design is an easy and affordable solution.

"All non-electrical parts in the rover were modeled using Alibre, including the wheel assemblies and the frame components that hold the various pieces together," says Chan.

"The parametric nature of Alibre made it very easy to adjust the design, especially when it came to making holders for the controller PCB and batteries. Every engineer should love parametric design. Being able to simply double-click and edit a value to change the design is wonderful."

With today's low-cost parametric software in conjunction with other convenient 3D technologies, inexpensive outsourced fabrication, anybody can explore the full extent of their engineering perversion.

"Digital manufacturing, 3D printing, and laser cutting match well with a design package like Alibre's, which is able to export to useful formats like STL, DXF for prototyping and production," says Chan. "I've used consumer services like Shapeways and Ponoko with Alibre models in with great success. I really appreciate how these companies are bringing parametric modeling and digital manufacturing into the reach of students, hobbyists and artists."

About John Chan
John Chan writes the engineering blog You can also contact him through at his profile:

3D model and manufacturing drawings: Alibre Design 2011

About Alibre, Inc.
Alibre is the leading global provider of cost effective professional grade mechanical CAD, CAM, and PDM solutions. Founded in 1997, Richardson, Texas-based Alibre is led by Chairman and CEO J. Paul Grayson (previously CEO of Micrografx) and other graphics visionaries who are changing the landscape of 3D mechanical CAD/CAM software. Alibre develops Alibre Design™ and Alibre CAM™, the fastest growing parametric CAD/CAM solutions on the market. A small fraction of the cost of comparable software, Alibre Design offers the same core features as SolidWorks, Pro/E, Inventor, and other mid-range solid modeling packages at a cost that is affordable to any business or individual. Alibre CAM extends Alibre Design to provide integrated 2 1/2 to 5 axis CNC machining. Used by an immensely diverse user base, Alibre Design and Alibre CAM provide design and manufacturing solutions to Fortune 500 companies, small businesses, consulting firms, machine shops, start-ups, hobbyists, inventors, teachers and students. Alibre products are distributed in 50 countries and in 15 languages. For more information on Alibre, or for a free trial of Alibre Design and Alibre CAM, please visit All trademarks and registered trademarks are the property of their respective owners.