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Feet Part 1:  The Critical Role of Feet

2/5/2017

4 Comments

 
​Have you ever walked in ski boots that limited your ankle's movement?  Or in a lower leg cast?  Without being able to strike heel first and then roll onto our toes we're forced to walk peg-leg style, revealing how large of a role active feet play in walking.

Mechanical walkers can similarly benefit from active, articulated feet. We began exploring adding some sort of active heels and toes after the first walking tests of our SUV-scale TrotBot revealed we had insufficient foot-contact with the ground.  
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​The first result of that effort was TrotBot's heel linkage.  As you can see in the diagram below, TrotBot's heel strikes before the main foot, taking the weight while pushing backward to continue driving the robot forward.  The resulting smoother gait reduces both torque and power requirements (for an analogy of why bumpy gaits require more power, think how much harder it is to do lunges than it is to simply walk).  
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​
Another benefit of TrotBot's heel is it steps higher on the backside of the foot-path, allowing TrotBot's rear legs to step about as high as the front legs to avoid getting stuck astride obstacles, as can be seen in this heel-path simulation:
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​​​Without its heel, TrotBot's rear legs probably would have gotten stuck on some of these 2x4s:
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We've also played around with a few ideas for active toes that push down on the ground as the foot begins to lift:   
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Mindstorms TrotBot with Active Toes
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Using shaped feet to smooth gaits is explored next in Feet Part 2, and the impact of TrotBot's active toes are explored in Feet Part 3.
4 Comments

Professional TrotBot LEGO Instructions from Catweazel

2/5/2017

1 Comment

 

Catweazel, AKA Michael Leefers, was kind enough to create computer-rendered instructions for building TrotBot in LEGO, and share them with us!  Instead of using 3/16" aluminum rods to prevent TrotBot's inner frame from sagging, Catweazel cleverly added a Technic beam to connect the inner frame to the outer frame, which helps to prevent the plastic support axles from bowing.  This is the same solution I was planning on using for the support rods of my large bamboo TrotBot - great stuff!
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You can access or download Catweazel's instructions and efficiently purchase parts via his Rebrickable page.  Thank you Mr. Leefers!
​Ben
1 Comment

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  • Home
  • Walker ABC's
  • Build Instructions
    • TrotBot Builds >
      • TrotBot Linkage Plans
      • TrotBot's Legs Simplified
      • Quadruped TrotBot
      • Hexapod TrotBot
      • TrotBot
      • TrotBot, Ver 3
      • Mindstorms TrotBot, Ver 3
      • Wooden TrotBots by Automata Korea Design
      • 3D Printed TrotBot by Scott Anderson
      • Mindstorms TrotBot, Ver 2
      • Mindstorms TrotBot
      • Large-Scale TrotBot
    • Strider Builds >
      • Strider Linkage Plans
      • Strider Ver 3's Legs
      • Strider Ver 3's Frame
      • Mindstorms Strider Ver 3 Mod
      • Strider
      • Strider's Legs Simplified (ver 2's)
      • RC Strider
    • Mechanical Spider >
      • Klann Mechanical Spider - Climbing Mod
      • Klann's Spider, EV3 Long Legs
      • Klann High-Step Mod
      • Klann's Spider, Ver 2
      • Mindstorms Klann
      • Klann's Spider, Ver 1
      • Klann's Linkage Plans
    • Strandbeest
    • LEGO Spot Micro
    • Linkage Warm Ups >
      • Lever Paradox
      • LEGO Biters
      • LEGO Punchers (4 bar linkage warm-up)
      • LEGO Hopping Robot
    • Hiro Labo
    • Whegs (wheel-legs)
  • Customize
    • Strider Linkage Optimizer
    • Klann Linkage Optimizer
    • Strandbeest Optimizer for LEGO
    • TrotBot Optimizer
    • 4 Bar Linkage Optimizer
    • 4 Bar Walking Linkage
    • 6 Bar Walking Linkage
  • Linkage Simulation
    • Python Linkage Simulator
    • Scratch Linkage Simulator
  • Blog