Transition Between Environments

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Purpose

With other functions that allow for terrestrial and submersible travel, a subsystem that allows for the dynamic transition between environments is essential to providing rapid support to users in the field.

Design Objective

The goal of this subsystem is to enable the robot to seamlessly transition between aqueous to terrestrial environments as an amphibious robot. This system will likely be integral to the climbing and scaling systems when encountering rocky shores, swampy areas, and other transition areas with unusual features. In the complex amphibious environment, the robots should possess multi-capabilities to walk on rough ground, maneuver underwater, and pass through transitional zones such as sandy and muddy terrain. These capabilities require a high-performance propulsion mechanism for the robots. Ultimately, amphibious robots have the main advantage in this entire stance.

Various mechanisms have already been designed that incorporate amphibious technologies, including:

RSTAR (Rising Sprawl-Tuned Autonomous Robot)

This traditional wheeled robot kept the round wheels on one side but replaced the propellers with spoked rimless wheels on the other. It moved across flat terrain using the round wheels, but then actually flipped itself over to use the spoked wheels for going over rough, uneven ground (Coxworth).

Pilant Model

This model uses mechanics similar to a grain auger or a screw conveyor; the robot is able to glide through tough terrains and then uses the same “fins” to help glide through water using large surface areas that make it more efficient than a traditional propeller. See it in action. They also provide a great way to gauge the success of the robot using its endurance in both environments and its agility in both as well (Aouf).

Eel Model

This type of robot uses central pattern generators (CPGs), which are sequences of neural circuits (the biological kind) that generate the sort of rhythms that you see in eel-like animals that rely on oscillations to move (Ackerman).

Original Concepts

Metrics

  • Transition time between environments (ideally in 20 seconds)
  • Able to transition unusual terrain without flipping over
  • Types of terrain and “landing zones” able to be traversed

Constraints

  • Waterproof
  • Must be small enough to test full functionality in a standard pool
  • Neutrally buoyant

Relevant Codes and Standards

  • Will meet the codes and standards addressed in both the land movement sub-function and the swim sub-function simultaneously at all times in case of hazardous and unpredictable environmental conditions

Next Steps

  • Understanding of what it will take for the robot to survive in the water and on land 
  • Propeller knowledge and understanding of the necessary propulsion to balance and keep upright as the robot proceeds deeper in water from land transition
  • The physics of how both motion will occur on land and in water 
  • Buoyancy to be submerged but not sink and stay submerged as we enter the water 
  • Fluid mechanics in the air and water

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Citations

  1. Ackerman, Evan. “Robot Shows How Simple Swimming Can Be.” IEEE Spectrum, IEEE Spectrum, 12 Aug. 2021, https://spectrum.ieee.org/swimming-robot-eel-epfl.
  2. Coxworth, Ben. “Sprawling, Crawling Robot May Someday Save Lives.” New Atlas, 18 July 2018, https://newatlas.com/rstar-sprawling-crawling-robot/55516/?itm_source=newatlas&itm_medium=article-body.
  3. Rima Sabina Aouf. “Amphibious Velox Robot Uses Undulating Fins to Swim and Crawl.” Dezeen, 10 July 2019, https://www.dezeen.com/2019/02/07/amphibious-velox-robot-technology/.