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DeepDirtDiving Owltomobile

Animal Burrow Exploration Vehicle

Testing whether the Tamiya tank with no weight added could pull a 28 gauge power cable through the realistic burrow simulation testing site.

Spring 2020 MAE 156B Sponsored Project

University of California, San Diego

The full report including the executive summary can be found here. 

Sponsors:

This project is sponsored by the San Diego Zoo's Institute for Conservation Research in collaboration with UCSD's Engineers for Exploration. Our contacts from each sponsor are Ian Ingram and Eric Lo, respectively.

Motivation:

This projected is motivated by the need for more research on burrowing animals; specifically the western burrowing owl. Current technology used to investigate burrows is expensive and often ineffective. Better technology will help researchers understand the topography of burrows, their microclimates, the animal population, and the growth behavior of burrowing animals among other valuable collectable data. Our goal is to aid in the advancement of such technology through building a small vehicle that can traverse complex owl burrows.

“Owl.” San Diego Zoo Global Animals and Plants, animals.sandiegozoo.org/animals/owl

Schematic of the artificial burrow used by the Institute of Conservation Research to act as homes for the Burrowing Owls. These

burrows have a nominal diameter of 4 inches, similar to the natural burrows used by the Owls.

Taken from Burrowing Owl Artificial Burrow Assembly and Installation Guide, Institute of Conservation Research at San Diego Zoo

Background:

Many animals make their homes underground in burrows. The burrows afford those species all sorts of advantages, but present a real disadvantage to researchers, particularly conservation ecologists, who could use more data about the structure of the burrows and the activities of the animals living within them. Our sponsors aim to develop a vehicle that is generally capable of successfully navigating complex burrow systems that are comprised of tunnels and cavities that range in diameter, cross-sectional shape, inclination, wall characteristics (e.g. texture, softness, crumbliness), and other attributes that would likely factor into a vehicle's ability to get from the entrance of the burrow to every part of the burrow system. A main restriction in our vehicle is size; the diameter of natural burrows has been reported to be as small as 11 cm. Thus, maintaining a small size is critical for the success of this project.

The key components that an ideal burrow navigating vehicle would feature are as follows. Due to COVID-19, only the mechanical components that were known to cause failure were investigated. These are in bold:

Vehicle Key Components: 

• • Chassis 

  • Treads

  • Wheels 

  • Tether (with Spool) 

  • Power supply 

    • Either through tether or onboard

  • Microcontroller 

  • Camera 

  • Additional sensors

    • Temperature

    • Humidity

Objectives:

Originally, the team's objective were as follows:

1. Primary Objective: build and test a vehicle capable of transversing entire lengths of artificial and natural burrows

2. Secondary Objective: Improve the vehicle's resistance to the elements by making it water and dust proof

3. Wow Factor: Incorporate complex sensors (temperature, humidity, geopositioning) as well as the ability to drop off and retrieve data sensors

However, due to COVID19 disruptions, access to the machine shop, 3D printers, and other campus facilities was no longer an options. This required a change in our objectives focusing on theoretical analysis and component testing in order to report recommendations to the sponsor if building a finished product wasn't possible. The new objectives could be summarized as follows:

1. Primary Objective: Perform literature review on existing solutions, test high risk components, and finalize a recommended vehicle design

2. Secondary Objective: Improve the PVC piping for artificial burrows as a rapid test rig for any developed prototypes

3. Wow Factor: Build the vehicle – or modify an existing tank – that is able to navigate complex tunnels

Final Design:

CAD of the prototype design

In order to reliably navigate rough terrain, provide adequate soil thrust, and distribute the vehicle's weight more efficiently, a tracked vehicle design was chosen for this project. The limitations to the ability to manufacture or assemble  a prototype due to COVID19 disruptions restricted our team to theoretical analysis, and isolated component testing. Thus, we purchased a test tank (Tamiya tank) and performed tests to quantify its performance in soil conditions. As going inside a burrow necessitates a safety tether that may double as a communication line, we carefully analyzed the tension that may arise in a tether inside the burrow and evaluated the Tamiya tank's ability to pull the tether. We also researched and tested ways to improve traction of the tank treads with soil to increase its ability to pull the tether.

Another component we analyzed is an on-board spool. By having it on the tank, we theorized the ability to bring down the tether's pull on the tank to zero. Thus, negating the risk of the tether and allowing for improved locomotion inside the burrow. 

Project Summary Presentation: