Sinusoidal Drive

Axially Driven Biomimetic Motion

Overview

The purpose of this project is to mimic the movement of sea snakes and other animals capable of locomotion in multiple environments. There are different ways to do so, including by using nitinol wire and arrays of servos. However, without essentially building a snake from scratch we will be unable to replicate its performance without leveraging mechanisms that nature cannot use.

Approach

To successfully emulate the performance of these animals, we must leverage an anchient mechanism, the Archimedes screw. The reason behind this is simple - When these screws are hollow, they can flex and move. This is a common technique used in auger conveyors to move grain. Since Archimedes screws are ready to move all-terrain vehicles everywhere, from the arctic to swamps, the question is can we make a driven helix flexible?

Current Progress

The initial version of the sinusoidal drive proves that a flexible driven helix is possible, the helices can drive the robot forward on grass, while exhibiting the desired flexibility, as seen in a variety of tests. However, that isn't to say that there aren't issues, the main problem with using an entirely flexible helix is that the robot can "droop" dragging itself along the ground and not having enough power to push itself forward on solid ground.

Next Steps and Potential Future Research

To fix this, we needed to give the robot a "skeleton" with rigid helices forming the bones holding the heavier parts up to ensure that the robot will never "droop", these rigid sections will be connected by flexible helices enabling the same desired flexibility without any of the drawbacks similar to the biology of actual snakes. If these helices can be used to drive an exterior skin on the robot, carrying the movement with them while maintaining flexibility it can open a wide variety of possibilities from robots that can go on land as easily as underwater, to more odd configurations such as flexible thrusters.

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