P19229: Robotter
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Detailed Design

Table of Contents

Team Vision for Detailed Design Phase

Our team goal for this phase was to finish detailed design before the end of the semester. We focused primarily on the leg and tail subsystems with a secondary focus on waterproofing, intermediate structures (spine, hips, shoulders), and RC.

We have mostly settled on a final design and all critical components have been selected. We have begun a bill of materials which we will flesh out as we continue to finalize component specifications. A few things are still in flux though, like the final torso dimensions.

Feasibility: Prototyping, Analysis, Simulation

Leg Motor Selection

We had a hard time finding motors that met all of our specifications, but we did find a continuous rotation servo motor that meets all of our design specifications besides being waterproof. We will order one to start and verify that it works and that we are able to successfully waterproof it before ordering the rest. The specs for the motor can be found here

Leg Design

In order to save money on servos we looked into different mechanical designs to have a leg with a joint be moved by one servo. We found the Theo Jansen walking machine and used it as a basis for a new leg design.

Theo Jansen leg design

Theo Jansen leg design

It was then 3D printed and tested to make sure it would work in real life. The only issue is that the design requires a 360-degree servo in order to work and after exhaustive research, there are none available with the torque we need that are also waterproof. This meant that the only option was to manually waterproof the servo so we tried it out with some cheap servos we already had. We tried different sealants but overall the waterproofing was a success so we are moving forward with this design. The continuous servo was ordered and will be waterproofed and tested upon arrival and in the meantime the CAD is done.

Theo Jansen leg design prototype

Theo Jansen leg design prototype

Prototype of Tail Assembly

Prototype of Tail Assembly

The above picture shows our first 3-D printed prototype of one tail section.

Drawings, Schematics, Flow Charts, Simulations

CAD Model of Tail Assembly

CAD Model of Tail Assembly

A waterproof servo will be placed inside the rear housing and will provide the torque needed to move the tail from side to side. This side to side motion will generate thrust allowing the Robotter to swim.
Full CAD Model of Tail Assembly

Full CAD Model of Tail Assembly

The above shows the full tail assembly. This will be connected to the body via the shaft that will couple to a servo that will be mounted on the rear of the body.
Full CAD Model of Body

Full CAD Model of Body

This shows the CAD assembly of the ribs and spine. Eventually the tail and legs will be attached to it via 'hip' and 'shoulder' pieces (still being designed).
Tail Attachment

Tail Attachment

This is the CAD model of the attachment that will be screwed to the ribs that holds the tail.
Leg Attachment

Leg Attachment

This is the CAD model of the attachment that holds the legs that will be screwed to the ribs.
Total Hip Assembly

Total Hip Assembly

This is the full hip design assembly that will hold both the tail and the legs.

Bill of Materials (BOM)

Currently these are the required materials for purchasing. A budget increase request form will be eventually presented to the client, if necessary.

Full Current Bill of Materials

Full Current Bill of Materials

Test Plans

Tail Testing

Design and Flowcharts

Control Design - Continuous Leg Motor

Control Design - Continuous Leg Motor

RC Transmit and Receive Design

To implement an RC Controller for our Robotter, we need to understand how the controllers communicate with an Arduino. RC Controllers typically communicate on various channels, at 2.4GHz. Each channel corresponds to a different operation on the physical controller. For example channel 1 may be a joystick and channel 2 may be a button. That signal is transmitted from the controller to a receiver, with a matching number of channels. Many controllers fortunately come with a matching receiver. The receiver will take the signal, at 2.4GHz, and then output a converted digital signal to the Arduino. The Arduino can then map the receiver's signal to values that correspond to something the servos understand. The figure below outlines how the RC Transmit and Receive would work in the system.

RC Trasmit and Receive

RC Trasmit and Receive

Risk Assessment

No changes were made to our risk assessment during this phase.
Current Risk Assessment

Current Risk Assessment

A working copy of our risk assessment can be found here.

Design Review Materials

Our Design Review Slides can be found here

Plans for next phase

A working copy of our project plan can be found here.
Individual Plans
Jacob Huppe
Ian Kay
Jonathan Travers
Drew Meunier
Chris Ugras
Mia Garbaccio

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