P17044: Human Tremor Mitigation
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Preliminary Detailed Design

Table of Contents

Team Vision for Preliminary Detailed Design Phase

Key Questions for This Phase

How is the tremor force distributed along the hand?

  1. What is the force along each point along the hand?
  2. What is the ideal point to add regulative forces to compensate tremor forces?

What type of elastic material will be able to house all of the necessary components without hindering actuator or sensor function?

  1. Where does our glove need to be elastic?
  2. Where does our glove need to rigid?
  3. How elastic?
  4. How rigid?

Is the Magnetic Braking idea feasible?

  1. Will be proved out with a test fixture.
  2. What friction force will the Magnetic Braking create?
  3. Is the friction force from the Magnetic Braking enough to mitigate our ideal tremor?

Is our designed electric system feasible?

  1. Electrical prototype will be built to prove out or electrical design.
  2. Components for electrical prototype will be purchased.

Are flex sensors feasible for our application?

  1. Will purchase a few stretch sensors for testing.
  2. What is the acquisition time for stretch sensors?
  3. Is the stretch sensor acquisition time fast enough to detect desired movements?
  4. What are the desired movements we want to use the stretch sensors for?

Engineering Theoretical Analysis

Force Detailed Analysis in the system

By obtaining a mass distribution curve, the relevant mass contributing to force at each point can be related to a point mass.

Mass Distribution in Hand at each point relative to hand full length

Mass Distribution in Hand at each point relative to hand full length

Therefore, Using the maximum length of the hand at full extension and maximum tremor amplitude at maximum length a relation of tremor amplitude propagation can be obtained at each point using similarity.

 Movement Relation

Movement Relation

When plotting the findings using Matlab, the below plot can be obtained
 Force Distribution for one cycle

Force Distribution for one cycle

However, due to the nature of the tremor, the largest contributors to the force are located in the palm while the fingers could be a propagation of resonance.
 Relevant area of application

Relevant area of application

Link to the live document here

Forces Reponses due to actuators

Considering a force diagram of parameters on system and their orientation. The force components caused by the actuators perpendicular on the hand can be disregarded since the system is an active damping system rather than active actuator though application of force.

System Analysis for forces

System Analysis for forces

The couples caused by the wrapping of the wires around the fixtures of the system from the side will also cause the system to be able to resist pronation and supination.

 System couple analysis

System couple analysis

Link to document here

Strength Analysis Based on Material choice

The design of the glove will include 2 plates to distribute forces around the plate.
Top View of the Glove

Top View of the Glove

Bottom View of the Glove

Bottom View of the Glove

Based on the force targets claimed, the displacement in the acrylic material is maximized at around 0.00136 mm which is negligible and wont be a major contributor to pinching or bruises.

Plates Deformation

Plates Deformation

looking at the stress and strain distributions, it can be deduced that the force is well distributed from the stress and strain numbers observed

Stress Distribution in plates

Stress Distribution in plates

Strain Distribution in plates

Strain Distribution in plates

Therefore, the material decision thus far is transparent Acrylic Plastic

Material Considered

Material Considered

Link to the live document here

This model was created in Solidworks and will be used to plan the layout of our prototype as well as testing the stresses and strains exerted on the glove when the forces generated from the tremor are applied.

Top View of the Glove

Top View of the Glove

Bottom View of the Glove

Bottom View of the Glove

The base material will be made of neoprene which is a Class 1 medical grade, breathable material. This will provide the barrier between the components and the patients arm to prevent pinching and thermal issues.

Neoprene glove

Neoprene glove

Feasibility Test/ Prototyping

3D model of pulley for fixture

3D model of pulley for fixture

3D model of magnet holder

3D model of magnet holder

Magnet test fixture

Magnet test fixture

3D printed pulley

3D printed pulley

Two ceramic magnets held by 3D printed spacer

Two ceramic magnets held by 3D printed spacer

Electro magnet test

Electro magnet test

Hanging magnetic force test

Hanging magnetic force test

Link to the Preliminary Fixture Results here

Link to the Fixture Test Protocol here

Link to the Magnet Rating Protocol here

Electrical Designs

Schematic and Bread-Boarding

An electrical schematic and bread board representation were generated using Fritzing, a software that allows you to mock up bread board designs with common components. These

Bread-Board Layout

Bread-Board Layout

Bread-Board Layout

Bread-Board Layout

Additional Feasibility

Full details on the stretch testing are available in the following link. Stretch Sensor Feasibility

Bread-Board Layout

Bread-Board Layout

The blocks shown above were the first test fixture for the stretch sensor. with this system the cable was stretched at different distances and the resistance relationship is shown in the photo below.

Stretch vs Resistance

Stretch vs Resistance

After proving out the stretch / resistance relationship a custom sensor was made

Custom Sensor

Custom Sensor

Stretch Sensor Test

Stretch Sensor Test

Using this sensor the relationship between resistance and flexion of a joint was shown.

Flexion Notes

Flexion Notes

Resistance vs Flexion

Resistance vs Flexion

Bill of Material (BOM)

Bill of Material (BOM)

Bill of Material (BOM)

Link to document here

Test Plans

Engineering Requirements with Test Plans

Engineering Requirements with Test Plans

Link to the live document here

Link to Preliminary Test Plans here

Risk Assessment

Logistical Risks

Logistical Risks

Technical Risks

Technical Risks

Link to Risk Document here

Plans for next phase

Key Questions for Next Phase

Will the Electrical System work with Actuators

  1. How are we going to attach magnets to electrical system?
  2. How does the magnet function on the test fixture while attached to the electrical system?

Can we attach the prototype electrical system to Fabric?

  1. How will electronics fasten to fabric?
  2. What elasticity fabric do we need?
  3. How rigid do we need the ribbing along device to be?

How will the magnetic brake attach to electrical system?

How will different materials perform as brakes?

  1. Test different materials in braking fixture.
  2. How hard is it to fabricate each material?
  3. How does the Fixture results map to our actual system?

How will external forces effect the system?

Link to Gantt Chart here


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