P18319: Lockheed ATLAS

Systems Design

Table of Contents

Team Vision for System-Level Design Phase (Kyle)

The goal of the System Level Design phase was to establish a functional decomposition which was used to generate different potential concepts. Using a Pugh Matrix, each concept will be compared using important criteria derived from the Engineering Requirements of the project.

The team was able to generate three different concepts and used generated criteria to make a final system selection. In this case, the 2 degree of freedom (DOF) robotic arm was chosen as the best concept to move forward with. Using this concept, a system architecture was made. Risks were updated with specific system design issues the team anticipates.

Motor and microcontroller benchmarking began, and high level software and electrical schematics were generated. Preliminary test plans, and a failure mode effect analysis were also created. Using the selected design and component benchmarking, a preliminary budget was made.

Updated Requirements

Following the onsite customer visit the following changes were made to the system requirements.

public/Systems Level Design Documents/Updated Customer Requirements.PNG

Functional Decomposition

Functional Decomposition Diagram
public/Systems Level Design Documents/ATLAS Functional Decomposition.png

Morphological Chart and Concept Selection

Morphological Chart (Mark)

Morphological Chart
public/Systems Level Design Documents/Morph Chart.JPG

Communication Options (Sarah)

Option 1 *Option 2* Option 3
Option 1 Option 2 Option 3

Concept Development (Kyle)

The following potential system designs were developed using a combination of benchmarking and engineering and customer requirements, as well as other tools developed during the first two phases.

Design Concepts
2 Degrees of Freedom Robotic Arm Rotating Rail Linear XYZ
public/Systems Level Design Documents/2-DOF Robotic Arm.png public/Systems Level Design Documents/ATLAS_Helicopter_concept.JPG public/Systems Level Design Documents/Helicopter_Concept_Explanation.png public/Systems Level Design Documents/3D Printer Concept GIF.gif public/Systems Level Design Documents/3D_Printer_Concept_Explanations.png

Feasibility: Prototyping, Analysis, Simulation

Material Selection for Weight (Harvick)

6 different materials were analyzed comparing the weight to strength ratio, as well as weight estimates of various other components such as a microcontroller and stepper motors. This will be used to determine the feasibility of the 10 lb customer requirement.

Weight Analysis
public/Systems Level Design Documents/Weight Table.PNG

As shown above, carbon fiber has the best weight to strength ratio, and its total material weight is about 3.5 lbs. 6063-T6 Al is the second choice of material. Cost will be the final step in determining material selection.

Feasibility of Polar Coordinates (Kyle)

Traditional cartesian coordinate systems dominate the 3D printer market. However, with weight considerations, a system that uses polar coordinates would be more likely to be under the 10 lb limit.

Assuming we can accurately use a rotary encoder as well as a linear transducer to measure distance, the following is how you convert cartesian coordinates on an MFD to polar coordinates:

Converting from the cartesian coordinates above, to polar coordinates, r and theta, is done using the following equations:

X = r*cos(theta)

Y = r*sin(theta)

Knowing desired X and Y location, and using the rotary encoder to measure theta, The use of polar coordinates is relatively easy, and could be implemented in the software.

TCP/IP Interface Microcontroller (Sarah)

Even though the Ethernet requirement (TCR/TER 4.1) was removed after the visit with the Lockheed Martin team, it still might be possible to have TCP/IP functionality to communicate with TWIN directly. Below are two options for implementing an Ethernet connection, an adapter and a microcontroller board which has Ethernet ability built in. Feasibility of either would be best tested using prototyping.

Selection criteria is as follows:

Ethernet Adapter (ENC28J60) with Teensy 3.6 FRDM-K64F
public/Systems Level Design Documents/ethernet_adapter.jpgpublic/Systems Level Design Documents/teensy.jpg public/Systems Level Design Documents/FRDM-K64F.jpg

Memory Considerations for Microcontroller

Confirmation that the microcontroller will be able to read in the entire configuration file and run in a loop for a consecutive 12 hours will be accomplished by prototyping on a Teensy 3.6.

Concept Selection (Matt)

To evaluate system and subsystem concepts, Pugh matrices were generated using important criteria from the systems requirements.

Pugh Matrix
public/Systems Level Design Documents/Pugh_Final_Concept_Selection.JPG

As shown in the Pugh matrix above (detailed chart in the link), the robotic 2-DOF robotic arm was chosen as the best concept based on the criteria laid out above. Ten criteria were developed and weighted based on importance. Scalability, weight, and software complexity were weighted most heavily.

Scalability and weight were the most critical customer requirements, so they were given the most consideration. Software complexity was also extremely important to the group because we have only one team member fluent in software development. Other team members will gain needed knowledge to support system development, but only one member with extensive prior knowledge.

Considering all the criteria, the 2-DOF robotic arm, relative to the traditional Cartesian design baseline, had a net score of one. The Helo concept had a net score of negative eight. Therefore, the robotic arm is the best design to fulfill most of the weighted criteria derived from the engineering and customer requirements.

Final Design Concept (Matt)

Following the decision to move forward with the robotic arm concept, a model of the MFD provided my Lockheed Martin was created in SolidWorks. A final model of the robotic arm was also created in SolidWorks.

2-DOF Robotic Arm
Animated GIF Expanded Analysis
public/Systems Level Design Documents/Robotic Arm SolidWorks/Robot_Arm_GIF.gif public/Systems Level Design Documents/Robotic Arm SolidWorks/Overall Explanation.PNG public/Systems Level Design Documents/Robotic Arm SolidWorks/Close Up Explanation.PNG
Test MFD
public/Systems Level Design Documents/MFD SolidWorks/MFD Assembly Picture.PNG

Benchmarking (Matt)

The following motors and micro-controllers are under consideration leading into a detailed design analysis.
Component Benchmarking
Motors Micro-Controllers
public/Systems Level Design Documents/Motor Benchmarking.PNG public/Systems Level Design Documents/micro_selection.PNG

Systems Architecture (Sarah)

public/Systems Level Design Documents/ATLAS System Architecture.png

Designs and Flowcharts

Top Level Software Flowchart (Sarah)

public/Systems Level Design Documents/top_level_flowchart_rev1.jpg

System Schematics (Mark)

See the Schematics Package for ATLAS.

ATLAS System Schematic Microcontroller Schematic
public/Systems Level Design Documents/System Schematic.JPG public/Systems Level Design Documents/SchematicMicrocontroller.JPG

Risk Assessment & Test Plans

Risk Management (Mike)

public/Systems Level Design Documents/Risk Management.png

Failure Mode Effect Analysis (FMEA) (Mark)

public/Systems Level Design Documents/MSD1 ATLAS fmea-1.png

Test Plan (Mike)

A preliminary Test Plan was developed to test system requirements.

Budget Breakdown (Mike)

Budget Breakdown

Plans for Next Phase

The action plan for Preliminary Design Phase is outlined on the Gantt Chart below.

Preliminary Design Phase Action Plan
public/Systems Level Design Documents/Ultimate ATLAS Gantt Chart.png

Lessons Learned (Kyle)

Peer Review Feedback from Problem Definition Phase (All)

Team Member Peer Review Action Feedback
Harvick Tang Generate meeting agendas to keep the team on task prior to meetings Consistently made agendas prior to all group meetings
Sarah Bentzley Ask for help when needed, and don’t take on too much work comparatively to the team. Ask for help and delegated tasks to the team when needed
Matt Craven Speak up more during meetings Consistently spoke up with opinions during meetings
Mark Min Arrive earlier to meetings Arrived on time, and in some cases early to group meetings
Mike Kelly Don’t stress yourself out so much Controlled stress level during concept development, which resulted in a better final product
Kyle McAlinn Resist being pessimistic coming into systems design Was more open to ideas and thinking outside the box

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