P18229: Robotic Otter
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Preliminary Detailed Design

Table of Contents

Team Vision for Preliminary Detailed Design Phase

Our team goal for this phase was to prototype and simulate subsystems and concepts that have a high risk. In this phase, we performed three main tasks.

Prototyping, Engineering Analysis, Simulation

Spine Prototyping

We prototyped the spine as it is the core system within our robot. We want this spine to be able to bend significantly; however, the math to determine the force required to do so is not well defined. To spec our motors, we needed to know how much torque they needed to provide. We took our prototype spine, attached a force gauge, and measured the force required to bend the spine 90°, the maximum bend desired for our robot. During the experiment, we noticed two important things; the natural bend in the tube is a significant factor in characterizing the tube's ability to bend, and the tube has the potential to buckle within the range we are considering.
Spine Prototype

Spine Prototype

Spine Simulation Test Setup

Spine Simulation Test Setup

Spine Simulation Test - click on the above image to view the test in action

Spine Simulation Test - click on the above image to view the test in action

Lessons Learned:

Silicone Part Casting

Silicone Spacers

Silicone Spacers

In order to prevent the spine tubing from kinking, we decided to prototype some silicone spacers to add additional structural support to the base spine. These prototypes were made in preexisting moulds for air muscles, and were to be sections cut out from these parts. This process produced the above part, which had large air bubbles in it, reducing the structural integrity of the part. The steps we believe are necessary to produce a more successful part are to use more silicone thinner, use a mould with a larger gap between the walls, and to stir the parts of the silicone mixture more carefully. For the spine prototype above, a similar air muscle which had already been manufactured, and which does not exhibit as many defects as our part, was cut into segments and used.

Drawings, Schematics, Flow Charts, Simulations

Otter Schematic

Otter Schematic

Otter Components:
 Small Vertebrae

Small Vertebrae

Large Vertebrae

Large Vertebrae

Spine Schematic

Spine Schematic

Fixing Vertebrae to Spine

Fixing Vertebrae to Spine

Otter Schematic

Otter Schematic

Spine Assembly Drawing in Isometric View

Spine Assembly Drawing in Isometric View

Spine Assembly Drawing Side View

Spine Assembly Drawing Side View

Large Vertebrae Drawing in Isometric View

Large Vertebrae Drawing in Isometric View

Small Vertebrae Drawing in Isometric View

Small Vertebrae Drawing in Isometric View

Bill of Material (BOM)

The current bill of materials for our robot can be seen below. Note that this is just a pure bill of materials; the budget is still not finalized, as the primary things we need to purchase, the motors, have not yet been specified. We are in the process of deciding the requirements for these items.
Current Bill of Materials

Current Bill of Materials

We have the items marked in yellow above available to us either through MSD or in Dr. Lamkin-Kenard's lab. The working bill of materials can be found here. The working budget can be found here.

Test Plans

As we move ahead in the detailed design, it is imperative that we proceed with certain goals in mind. The following preliminary test plans will allow us to stay focused and mold our design around the goals we must accomplish.

Preliminary Test Plans

Design and Flowcharts

Electrical Wiring Layout

Electrical Wiring Layout

Risk Assessment

Top 10 Risks

Top 10 Risks

A full list of our working risk assessment can be seen here: Risk Assessment

Parameters to calculate importance

Parameters to calculate importance

Plans for next phase

The primary goal for the next phase is to finish prototyping the crucial components so that we are prepared to start our build come the second semester. We also want to focus on ensuring that we have all of the documentation for our processes and simulations that we have done to date.
Plan Going into Phase IV

Plan Going into Phase IV

The working document can be found here.

Individual Three Week Plans

Team Member
Amanda
Corry
Curt
Ethan
Tiffany
Vaughn

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