Mechanical Engineer
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Walking Beast

ENGS 146: Computer Aided Mechanical Design

Design Objective: Design and fabricate a pedal-powered walking machine for class jousting tournament.

May 2017

Team of 5


The Competition.

In 10 weeks, each team of 5 had to design a machine capable of locomotion without the use of wheels from limited prefabricated parts and within a 5' x 4' x 3' size constraint. 

 

Each machine would compete in a round-robin style jousting competition. The object was to use a supplied 7ft lance to detach your opponent's magnetic ring from their machine. 

 

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The Final Design.

Awards and Recognition

Overall Competition Winner - "A Terror on the High Seas"

Fabrication Fit and Finish - "A Work of Art"

Our machine walked in Hanover's 4th of July Parade and Dartmouth's Homecoming Parade.

Now, it rests in Thayer's Atrium for visitors and students to ride.

 

The Process.

Concept Design: Machine Layout

During the initial phases of the project we focused intense effort on figuring out an optimal layout of our walking machine, given the shortcomings of using linkages for mobility instead of wheels. We quickly favored layouts that had three leg units because it was the minimum required for stability and additional leg units would increase manufacturing time. As shown in the sketches below, we considered a large variety of layouts - each featuring different ‘driven’ leg units, turning leg units, and chassis configurations.

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Boomerang Layout

The final layout of our machine featured 3 leg boxes arranged in an asymmetrical, reverse tricycle orientation. This configuration enabled the machine to turn without the use of a differential, placed the drivers weight over the driven leg box, and maximized the left turning capabilities for competition performance.

 

Detailed Design: Overview

With the overall layout decided, our next efforts focused on developing a high performance walking system for locomotion and the associated sub-component systems. For the walking system, we had to design a linkage, a novel crankshaft to support a set of linkages, and a leg box to surround and support the entire system. For the drivetrain, steering, and seat, we challenged ourselves to find the most creative, simple, and elegant possible solutions.

 
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Component Design: Seat

Our seat design prioritized rider pedaling ergonomics, quick adjustability, and simple fabrication techniques. After several iterations, the final seat featured custom upholstery for rider comfort, simple wing-nuts for quick fore-aft adjustability to accommodate the different sizes of our group members, and stable rider weight distribution.

 
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Fabrication and Assembly.

Our team's prioritization of design simplicity and manufacturability allowed us to complete the build process one week in advance of our deadline and perform many days of uneventful testing and small modifications. Each individual part was designed in its simplest, most manufacturable form while still maintaining functionality. Where possible, we used nominal sized stock and hardware. For more complex components requiring high precision and repeatability, such as the crank webs, we programmed each job in HSMworks and performed production in an assembly line fashion. 

 

Final Demonstration and Competition.

Despite the rain, four teams competed in the final jousting competition on the Dartmout Green. Our team received the overall competition winner and fabrication fit and finish awards. 

 

Walking Machine in Action

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