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String Theory

Alibre Design Puts Robotic Projects into Motion

Josh Sanderson is learning how to walk. More specifically, he's studying the nuances of walking, so he can program more refined robotic movements.

For the last five years, Sanderson has been using Alibre Design in his spare time for a variety of mechanical projects, including his recent robotic experiments using a simple biped walker, which he's named Stance. Stance moves through remote control and "sees" through a high-definition video camera.

"I'm fascinated with the problems around realistic motion," he says. "One of my motivations in this project is to see if we can get benefits out of putting robot movements on motion curves, so parts accelerate and decelerate more gradually." In common approaches to robotic control, Sanderson explains, programming causes the servo motors to operate at the full target speed of the desired motion. This accounts for the spasmodic and abrupt behavior of typical hobbyist robots. "Gradual acceleration, on the other hand, can help make the motion look more natural and improves the walker's stability," Sanderson says.

On the mechanical side, Sanderson found it is relatively easy to get started on building a customized robotic design in Alibre. Hobbyist dealers now sell many of the basic building units of a robotics project, including small motors, servos, and mounting brackets. Designers can choose to configure the components in different ways.

"Most of the parts that make up the bipedal are made by Lynxmotion and are from their Servo Erector Set product line. Lynxmotion provides 3D models of their parts in the Alibre format. As long as you are okay with using these pre-fabricated parts, it does not take much effort to download the part files, and then bring them into an assembly in Alibre Design," says Sanderson.

Once the basics of the platform are in 3D, Sanderson can tweak the design to suit his experiments, and add in custom parts, which he generally builds in his shop, based off of his Alibre plans.

Parametric controls in Alibre Design allow him to adjust sizes and positions to parts during iterative experimentation. "If I need to make custom parts, it's simpler to do the fitting on the 3D model. All the accurate measurements are right there,"

Sanderson explains. "I can adjust each of the parameters and have the models react immediately. Alibre Design is a high-level parametric modeler, which makes it ideal for prototypes." Currently a software developer in his own consultancy, JGS Technical LLC, Sanderson sees opportunity in the robotics field, and would like to move his programming and modeling skills into a new niche.

"What I do - business-level software - solves problems, but the solutions always remain in the abstract," says Sanderson. "Robotics brings software into some interaction with the physical world. Building and controlling the mechanics present a different set of challenges. That's what interests me most. "What I like about Alibre is that it is accessible to someone like me, who is self-taught and looking for business ideas. I didn't come up through the academic system, so I never had access to student versions of expensive engineering packages. Having the professional-level capabilities in Alibre has given me the chance to learn 3D modeling and access to new opportunities."

STANCE Technical Specifications

    Multi-part Walking Robot
    Volume = 1.139838668E1 in³
    Mass = 1.867860921E2 kg
    Surface Area = 4.276552646E2 in²

Design summary:

    Sheet Metal Frame
    Parts : 58
    Faces : 6166
    Edges : 16294
    Vertices : 10684
    Unique parts : 11

3D model and manufacturing drawings: Alibre Design Professional

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.