Monday, July 28, 2008

Walking Vehicles, Part 1

Vehicles that move across the ground usually have either wheels, tracks, or legs. A walking vehicle has the advantage on uneven terrain. You can base a design concept on many living analogs, for nature has no use for the wheel.

Above is a scratch-built arthropod-based vehicle from Dinotopia: The World Beneath. The small maquette helped to visualize it in three dimensions and from various angles. The design is based on an extinct shrimplike invertebrate.

In the story, the vehicle, or “strutter” as it is called in Dinotopia, gets out of control and fights another strutter, while Arthur Denison and his friends watch in horror.

One reason wheels never arose in nature is the difficulty of designing a circulatory system that could work across a turning axle. Birds, humans, and a few mammals use two legs, but four, six or more legs are more common. Below is a full-size working model of a Japanese armored tech.



Engineers who design the drive mechanisms for walking vehicles usually have to solve three problems: how to translate the energy of the motor to the back and forth movement of the leg, how to achieve balance, and how to steer and change direction.

Tomorrow: part two, including Arthur Denison's strutter.
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Addendum: Blog reader Scibotic has suggested these awesome YouTube videos. Thanks, Ben:

Mondo Spider, homemade walking vehicle with driver: link
Walking Sculptures, passive wind-powered beach walker with many legs: link
Big Dog, a four-legged autonomous vehicle that recovers balance on ice and uneven terrain: link

7 comments:

SCIBOTIC said...

There's a good number of videos of interesting videos on youtube.

Eg.

Mondo Spider: http://www.youtube.com/watch?v=8hfljB2wQD8
Walking Sculptures: http://www.youtube.com/watch?v=7tp182UdSYw
Big Dog: http://www.youtube.com/watch?v=W1czBcnX1Ww

innisart said...

In the series "His Dark Materials" (The Golden Compass, The Subtle Knife, and The Amber Spyglass), Philip Pullman creates a species which gets around on wheels. Their body shape when on all fours, rather than being rectangular with limbs at the corners, is diamond shaped, with legs fore and aft and and then laterally as well. They have sharp claws on the front and back legs, and during the species evolution, they found these hard seed pods that when they inserted their claws into them, created a wheel. They would travel around like scooters, pushing with their side limbs. The relationship was symbiotic, because the traveling on these seed wheels (after many miles) was the only way to crack the hard shells so that they could ripen and grow into new trees. I thought this was such a wild idea, and I enjoyed trying to visualize these creatures riding about like a motorcycle gang.

James Gurney said...

Thanks, Ben--I've added those links on the post.

Innisart: thanks for describing the Pullman vehicles. Everyone should check out Matthew's blog Underpaintings, which has some great material on DuMond's palette.

mordicai said...

I was going to mention big dog...if you found that interesting, this big dog parody is compelling in a weird way:

http://www.youtube.com/watch?v=VXJZVZFRFJc

Erik Bongers said...

Big Dog is impressive.
The first time I guess a robot has such fast reflexes.

Apparently funded by military.
Let's hope it's final purpose will be humanitarian.

gvdub said...

You should also check out the guys at Mechanical Propulsion Systems, aka Mechaps. They've been working on a mecha in the Mojave Desert for several years.

Justin said...

I saw a video where a one-legged robot, basically a pogo-stick, was kicked repeatedly by the researchers, who were trying to knock it down. For a one-legged creature, they'd solved the balance issue--short of a blow that would destroy the robot, they couldn't knock it over. Likewise, they'd made a four-legged robot work the same.

Apparently two legs is the real hard one.