P15005: Standup Motorized Platform
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Detailed Design

Table of Contents

Subject Matter Expert Interview Notes

Dr. Mark Kempski

Dr. Wayne Walters

Ms. Mary D'Amico

Morphological Analysis

Morphological Analysis for Lifting Design

Morphological Analysis for Lifting Design

Prototyping, Engineering Analysis, Simulation

Original Concept Design Drawings

See drawings section for drawings of current model. For old drawings, see the Detailed Design Documents depository, and find the file needed.

Concept 1 includes two typical linear actuators that are positioned on the back of the chair.

Pros

Cons

The four bar design only needs one actuator, and uses a rectangular system to convert the linear force into rotational motion.

Pros

Cons

The scissor jack concept only requires one motor and uses a scissor like motion to extend in a linear motion.

Pros

Cons

The double actuator with mechanical advantage uses two actuators to lift the chair, and some lever arms to keep the chair rotating around the correct parts.

Pros

Cons

Lift Design Pugh Analysis

Lift Mechanism Pugh Analysis

Lift Mechanism Pugh Analysis

Before we could do a final pugh analysis, some stress, force, and center of gravity analysis needed to be done.

Stress Analysis

Stress Analysis

Force Analysis

Force Analysis

Force Analysis

Force Analysis

Force Analysis

Force Analysis

Force Analysis

Force Analysis

Center of Gravity Analysis

Center of Gravity Analysis

Tipping Angle Calculations

Tipping Angle Calculations

Along with these analyses, we need to have an idea of where the actuators will be placed.

Actuator Placement

Actuator Placement

FINAL PUGH ANALYSIS

After many changes on our design, we decided to determine if one single actuator in the center would be better than two actuators on the outsides. Our results are shown here.

Final Pugh Analysis

Final Pugh Analysis

Our results are as follows:

Selected Actuator

Selected Actuator

Harness Concepts

Top Harness Concepts

Top Harness Concepts

The concepts shown here for the top harness concepts are all existing harnesses on the market. The ideas are all pretty similar here, but the cross harness, and the body point chest harness seem to give the user the most mobility in the arms.

Bottom Harness Concepts

Bottom Harness Concepts

Like the top harnesses, all the bottom harnesses are all existing in the market. The Canyon harness, and windsurfing harness are all meant to take the force pulling outward from the front. This is not exactly what is needed in out application, so the bungee trampoline harness might be the best bet for our concept. With this, the forces are meant to be pulling from all different directions, which is ideal for this application.

After speaking with Matt McGarvey of Fonte Surgical, he suggested we come up with something simpler. Our harness would work, but it is unnecessary. Hence, we came up with a bar harness design.

Support Bar Concept Pugh

Support Bar Concept Pugh

Support Bar Legs Concept

Support Bar Legs Concept

Support Bar Chest Concept

Support Bar Chest Concept

Support Bars Stress Analysis

Support Bars Stress Analysis

Drawings, Schematics, Flow Charts, Simulations

Top Level Design

Top Level Design

Base Frame Design

Base Frame Design

The base frame could from the old chair could possibly be used in this application.

Lever Arm Design

Lever Arm Design

The Lever arm will be welded to existing base frame using perforated steel. Dimensions will be determined from stress calculations and actuator mount requirements.

Back Frame Design

Back Frame Design

The back frame will consist of round perforated steel tubing. The existing frame can be used with an additional welded bar for actuator mount.

Lift Mechanism Design

Lift Mechanism Design

The lifting mechanism will consist of a Transmotech actuator, and mounting hardware.

Box Frame Stress Simulation

Box Frame Stress Simulation

Box Frame With Cross Stress Simulation

Box Frame With Cross Stress Simulation

These stress simulations were simulated under a worst case scenario, where all of Megan's weight was on every point of the frame. As seen in the simulations, there is very little deformation in either model, and since just the box frame is cheaper to make, that's the idea that will likely be used in our design.


Electrical Design
Speed Control Concept

Speed Control Concept

The speed of the actuators will be controlled by potentiometers.

Limit Switch Mechanism

Limit Switch Mechanism

This limit switch mechanism shows where limit switches will be put so that the lift will not raise higher or drop lower than a certain point.

Electrical Schematic

Electrical Schematic

The electrical schematic shows how the power from the batteries will be distributed through switches to either the drive motor, or the linear actuators. The variable resistors are the potentiometers that will be used to control the linear actuator speeds. The limit switches will show how the lifting and lowering will be turned off when the limits are reached.

Limit switches are NOT included in the electrical schematic, because they are internal to the actuator.

Electrical Board Layout

Electrical Board Layout

This electrical board layout was done just for concept. It is not necessary, but will help keep wiring inside base neater.

Power Consumption

Power Consumption

It looks as if there is a concern with the battery life. However, the motors and actuators will not be fully loaded, and they will never draw 3Ah.

After each of the iterations of design, the final design with new support system was finally achieved.

Full Assembly

Full Assembly

A video of the chair moving from sitting to standing can be found here. This video was done without the support system for clarity.

Bill of Material (BOM)

View the current BOM here.

Project Schedule

Week 3-6 Schedule

Week 3-6 Schedule

Week 6-11 Schedule

Week 6-11 Schedule

The full MSD II schedule can be found here. Microsoft Project is needed to view this file.

Test Plans

View the up to date Test Plan here.

Risk Assessment

View the current FMEA here.

Design Reviews

View the Subsystem Design review presentation here.

View the Detailed Design wk 12 review presentation here.

View the Final week 15 review presentation here.


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