three degrees of freedom
three degrees of freedom
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GlideX By AutoMotion
General Design Project by
Blake Fuller
Brianna Christiansen
Cody Frost
Chawni Read
Justin Lavigueure
Re-imagining the Power Chair
This project came together in my junior year design project at Seattle Pacific University with a team of my peers. Our goal was to utilize "swerve drive modulus," currently available only through DIY creation or cottage industry FRC robotic team specialists, as the basis for a power chair which could navigate the built environment more closely to how bipedal people do.
What is swerve drive?
What is swerve drive?
"In FRC (First Robotics Competition) circles, swerve drive can be used for any drive train in which all drive wheels are steered. For this forum, the definition will be restricted to drive trains where all drive wheels are independently driven and steered. It is a holonomic drive train in which the robot can move in any direction and independently translate its chassis orientation.
From: https://team1640.com/wiki/index.php/Swerve_Central
Several of our team members, myself included, had past experience designing robotics as part of FRC teams and felt that drawing on the swerve drive technology developed there could serve as an interesting axis to design a wheel chair around as it enables the driver to move in three degrees of freedom, allowing driving to occur along all horizontal degrees of freedom simultaneously.
While the other two thirds of the team got to figuring out how to control it, the myself and the other mechanical engineer, Justin, got to making a strategy for the frame design. We decided on using 80/20 style aluminium extrusion in the frame as it would let us iterate on designs throughout the 10 weeks we had to build it without having to wait for final designs or redoing huge amounts of work re-cutting and milling changes. Changes were driven by the need to mount components and hand calculations to ensure physical structural viability.
Frame V1
First thing we decided is to make the frame 30 by 30 inches so as to be able to go through doors standard doors.
Frame V2
This design was tinkered with a lot, but the key change was the human and component driven rail spacing.
Frame V2 with components
This shows a rough mock up of where the seat and wheels would go on the frame.
Frame V3
The changes here were made to ensure structural stability and keep the design stable in motion.
Final Render
Final Render
Some key design elements here include the double layering of 80/20 bars on the bottom to spread out the rider weight, adjustable armrests utilizing the inherent structure of the aluminum extrusion to allow for adjustment according to rider height, and a sliding footrest which stows away under neigh the seat when not in use.
STATS
Top Speed: 1.8 MPH
Max Weight: 300 lbs
Degrees of Freedom: Three
Tippable?: NO
Distance on a Charge: 1 Mile Tested
Here is a demonstration of the final creation in use by yours truly.
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