Work night 11.29.18

Work Night

Date: 11.29.18
Time: 4:30-7:00 PM
Location: Logan HS
Students: Thaying, Avery, Caitlin, Thomas, Seth, & Alex
Goal: Begin to wire electrical boxes on tester and calculate the heel spring depression rather than compression values.

Seth drilling holes in tester for motor mount.

Seth wiring in electrical boxes

Boxes and capacitor for motor mounted.

Thomas and Alex working on notes for some compression/depression spring testing.

Avery and Caitlin working on the MIT APP.

Thomas, Alex and Thaying connecting fuse to switch.

Video of Seth drilling in the motor mount for the tester.

Alex and Thomas talked about testing methods and values associated with the heel strike. Piezo largely capitalizes on the heel strike. Our idea will capitalize on the spring depression from the heel. The voltage potential difference are striking. On compression we can harvest 5 j on depression we can harvest 20 j.

Caitlin and Avery explored the MIT App maker and tested the Bluetooth. Austin is making nice progress on that interface and display. We will need to find a way to show a power/energy level in the app.

Thaying worked on the blog.

Seth worked on the tester drilling holes for electrical box mounts and then worked with Thomas and Alex to wire in the fuse (one really well done wire). More work will be done on this on Friday.


Notes from the Hardware Team submitted by Alex M.:

• All kinds of li-ion batteries, need different chips for different types of batteries
• Have range of typically 3.0-4.2 volts

What can we do with tester

• Do a straight heel march for first test
• Can see compression and release of heel
• Force = Spring Constant*Distance + Generator
• More force when heel springs back (depression) rather than the compression
• Our testing doesn’t give accurate representation of release force
• Slowly generate at higher volt or faster at lower voltage. Which is more effective?
• Figure out how to attach heel of  tester to gear box.
• Could have plate on heel > to connecting rod > Gearbox
• Tester will give more accurate representation of what our generation time is.

What are key questions

• Gross generation
• What size capacitor
• High cap, low impedance
• Low cap, high impedance
• Chip max voltage less important because we can change capacitor size
• Some chips have taps for processors
• How does generator results compare to theoretical results
• What are our loss factors?

Table = yellow for release

• 
  

Plan for Testing

• Representative step cycle vs chart
• Is it realistic/reasonable
• Is it feasible?
• Look at return cycle
• Combination of forces and generators
• Where do we go to get good numbers?
• Could test extremes if we feel safe and note the interesting data
• Does it look good? Are we looking in the right area?
• What could be wrong
• Is something broken?
• How to fix it?
• What to we attack to improve efficiency
• Going for simple step to start
• Walk on heels

• If things go well

• What do we test next
• Test then review (Review and critique)  
• Add more components to system (Caps, chips, power circuit)
• Prototype battery load (dummy load{power supply})

Work Day 11.21.18

Work Day-Student came in on a day off school
Date:11.21.18
Time: 4:30-7:00
Location: Logan HS
Students: Caitlin, Avery, Paige, Alex, Thaying, Thomas

We took two steps forward and one back. The software side of the project
showed some promise with Austin successfully using an Arduino Uno and
Bluetooth module to interface with his phone to turn on and off an LED. Next
step will be to change the interface on the phone to show additional inputs.


Avery and Caitlin work on the Kiva software with limited success. We have a
hardware issue where the software does not want to run on our laptops. We
decided to see if Kiva is a viable option by the end of next week. Python
does run on it. We also have to work on our energy budget for the software
end.

Alex and Thomas worked on the locating the “hip joint” hole where a ½” hole
will be drilled in our tester for that pivot point. Calculations will have
to be redone for the motor location. Once that is done, we can begin to
mount and wire the motor.

Paige is making progress on the presentation and social media. She is ready
to go live with the accounts and keeping them updated will be a challenge.

Thiyang put up our first blog post and will have the second by the end of
next week.

The ordering process for tax exempt can be a pain. The same vendor
(Grainger) charged tax twice on our tax exempt account. The first one took
1.5 hours to resolve. The second time they said all states are tax exempt
except Wisconsin (which is not true) and cannot be resolved until Monday, Nov. 26th.

Other things we looked at:

Prosthetic Test System Alternatives
Basis for Force Generation
Direct mechanical thrust
Direct Weight
High mechanical advantage(scissors jack, etc.)
Discussed Alternatives; progress with conversion testing, idea conversion
model, electronics

Conclusions:
 With reasonable equipment, direct energy recovery mechanisms can be tested
With high mechanical advantage fixtures, with limited movement, full force
testing can be achieved. To achieve higher forces, knee joint must be used
in "scissors jack" configuration. Ref:
https://www.engineersedge.com/mechanics_machines/scissor-lift.htm

A variety of test conditions can be created with controlled, limited equipment

Prosthetic Test System Alternatives
Use of Gearmotor and mechanical linkages to control movement and test area
forces
Nominal speed: 1 cycle per second
Forces applied to test area: 20-50 lbs est.

Configuration 1: Direct "Scissors jack" application to maximize force with
minimal UUT travel
Configuration 2: Nominal force for testing energy features, foot rolling to
exercise different conversion modes using simulated artificial foot carrier
Configuration 3: Larger force capability for testing with combined
application samples including current sample of carbon fiber foot element
Configuration 4: Variable speed application to illustrate special cases
application (running?) Possible use of direct drive motor

Scissors Jack sequences:
Lifted leg element has no contact with floor
Initial contact of foot to floor is made, knee joint is bent reducing floor
thrust movement by 0.5 inch
Force is applied to knee joint to create foot thrust force, foot movement is
up to 0.5 inch OR foot element bending takes place
Full foot thrust force is developed
Conclusion: fixture must be adjustable in thrust distance and thrust attack
angle to develop forces required in the foot element under test(suggestion-
use human model in simulation poses) Restricting rollers can be used with
test samples in fixtures!

Austin working on the App that will monitor our device. Notice the LED is turning on and off through a Bluetooth connection he programmed.

Starting fabrication of our tester.

Electrical schematic of the motor wiring.

Thaying making a blog post.

Work Night 11.15.18

Work Night

DATE: November 8th 2018
TIME: 4:45 - 7:00 (2.25 hours)
People Who Attended:
Alex, Seth, Tanner, Avery, Paige, Thomas, Austin

Research Meeting for Prosthetic Limb - Lemelson MIT InvenTeam
Notes submitted by: Alex Magnuson


Today we discussed  a potential part-time software monitor system. The system would only be able to turn on in times when there are enough volts to sufficiently charge the smart puck battery and there are extra volts to turn the software monitoring chip on. When using capacitors it's worth noting that a larger cap will draw more current which in turn decreases the voltage. There is a happy medium between capacity and voltage. We learned about a circuit that will make our generators generate positive voltage in both directions.
We worked with a motor with a geared head that Seth and I did some testing with. We hooked it up to the oscope and with only about a half turn of rotation we could jump up to 10 volts and with a more aggressive spin we could get it up to 60 volts.
Seth and I finished our spring scale testing and have the data logged on a process documentation sheet. We tested the negative to positive voltage converter circuit and had good results with it.
As a team we also decided on what some of our main goals are. They include: when should the computer be turned on? Find out how many volts do we need to trickle charge the battery. When should the computer turn on, read, and then relay information? And most basic goal of getting enough power to battery.

Seth, Thomas and Alex gathering data from gearboxes.

Using an oscope to monitor voltage outputs.

Thomas working on a "puppet" to simulate the motion of the prosthetic limb.

More gearbox testing.

Paige working on public relations.

Taking in a lecture on systems integration.

The team working on fundraising opportunity and software/hardware interface.

Testing gearboxes.

Thomas cutting out the "Puppet" to simulate foot motion.

More testing on gearboxes.

Force Testing the Prosthetic Foot 11.13.18

Force Testing Result 11.13.18

Setting up the force testing system using wood clamps.

Aligning the force plate and calibrating software to conduct the test.

Video of students testing the force it takes the deflect the heel of the prosthetic foot 0-1/2"

Work Night 11.8.18

Work Night
DATE: November 8th 2018
TIME: 4:45 - 7:00 (2.25 hours)
People Who Attended:
Alex, Seth, Tanner, Avery, Paige, Thomas


Research Meeting for Prosthetic Limb - Lemelson MIT InvenTeam
-Discussed a testing device using gears and a self made treadmill to simulate walking
-It was undecided whether our previous design or the new design would work better
-Discussed how to measure energy when running tests
-Could use force plates, piezo or anything that generates feedback when stepped on
-Mr. Foye demonstrated the use of different gear boxes and a very cheap motor attached to a lever to generate power from about a half inch of motion at the axle
-One of the gear boxes was just direct to the motor and still generated about 5 volts with practically no resistance.
-The other was more resistive but still within reason but generated upward of 80 volts
-The use of an expensive motor and gear box could result in very substantial gains in power.
-We also made a small task list to complete

Submitted by: Alex Magnuson
Today Mr. Foye shared his idea on a new testing machine using gears to create a consistent step. In addition, the machine would also use a treadmill to help simulate the motion of walking. It is disputed whether we want to pursue our previous testing idea or the new one. We learned about ways to test our devices and methods to calculate power. We can use force plates or piezo or other measurements methods and use the feedback from those devices to calculate the power that a step makes. In testing the energy production device we can use the resistance of the motor and voltage created by using the formulas and steps below to figure out power produced. The use of two gear boxes with a motor at the output and a lever at the input. The first one had very low lever resistance but a lower output at around 5 volts. The second gearbox was more resistive than the first but generated substantially more voltage at around 80 volts. A google sheet table was made to show how load effected power output based on these demonstrations (Shared with Paige and Mr. J). It was mentioned that the tools used in the demonstration were very cheap and with higher end components we could get much better numbers. We also came up a small task list for us to complete (Below).

How to test for load on lever and generator
-measure terminal to terminal resistance
-Voltage divided by internal resistance + load resistance = current total
  -V/IR (Internal Resistance) +LR (Load Resistance) = I (Current Total)
-Power in watts = Current^2 * Load resistance I^2 * LR (Load Resistance)
-power*time = j
operating capacity = 13.5 Kj
Task List
1) Force deflections in various places on foot
1a) what tests
-single operation
-continual operation
1b) more ideas
-angle adjustments for ankle
Measurements
-force(piezo or force plate)
-deflection
-electrical (Voltage, Current, Power, Efficiency, Etc.)
2)Gear Motor requirements for testing machine
3) Detailing Design
4) Build Tester
5) Measurements

Mr. Foye going through some engineering calculations for testing device.

Thomas, Alex and Seth watching as Mr. Foye illustrates the testing device options.

Tanner uploading waiver forms on the Lemelson-MIT site.

Tanner, Paige and Avery working on the PR Powerpoint.

Students measuring electrical output from gearboxes with an O-scope. Notice how the voltage generated spikes on the scope into the 5 V range with this basic system. The other gear box was much higher into the 30-40 volt range.  

Alex and Thomas working on a lever and generator spreadsheet (and eating pizza).

Notes from our engineering consultant, Mr. Foye:

Session number one introduced the idea of a small DC machine as a generator

this session will present two examples of gear trains connected to small DC machines to allow basic testing

the goal of the idea is to develop basic feasibility of a battery charger for the vacuum pump puck, not necessarily a production design.

One principle of feasibility development is to attempt demonstration using a configuration which suggests a direction for the production design. To aid in this the technology available to be used should be readily available, to allow a basic size and cost assessment

with a demonstrated design configuration, observations may be made about possible refinements in an optimized design. The development of the feasibility model enables the development of basic design parameters, and the demonstration and testing to validate those design parameters as practical.

The majority of the work and then becomes team development of basic ideas using readily available technology, with follow-up testing and evaluation of demonstration prototypes. This avoids some of the problems with the requirement to do a fundamental design, not taking advantage of available technology, and then requiring the fabrication of new or novel components. Using available technology, the only barrier to a testable prototype is the fabrication of the application system, rather than the basic components themselves. Using engineering principles, some extrapolation in performance of the use of optimized components can be projected.

Exploration of geartrain drive with a DC machine

in exploring the operation of a geartrain driven generator, rapid construction of test prototypes which are expected to operate near the projected required performance can be done to explore the trade-offs inherent in those system approaches. A longer geartrain with more gear elements is capable of more variation in speed and torque output, which then can be applied to a broader range of generators that may be available. It may be more feasible to generate higher voltage and lower currents, if that is desired.

On the other hand a smaller geartrain will have a much narrower range of speed and torque, restricting available machines to limited output, which then requires more extrapolation of the generator design to obtain the desired output usable by the electronics.

Using this approach they system demonstration starts to take the shape of working backwards from the load requirement to determine power electronic conversion stages. The next step is extrapolation to the generator and mechanical links to determine the generator stage required performance.

The process then becomes:

0) identify the basic range of system operating parameters that may be acceptable

1) establish basic operating characteristics of the generator

2) establish basic operating characteristics of the geartrain

3) build demonstration generator and geartrain prototypes to explore operating characteristics using data from zero, one, two

4) system and storage suggested by the data from step three

5) evaluate the results of steps three and four; iterate on steps three, four, and five is necessary to arrive at a successful result or meet a deadline

6) adapt a prototype to a demonstration tester for display of the feasible result

Logan InvenTeam Work Night 11.1.18

Logan InvenTeam Work Night

Date: 11.1.18

Location: Logan HS

Time: 4:45-7:00 PM

DATE: November 1^st, 2018

TIME: 4:45 - 7:00 (2.25 hours) Tony Perry Meeting 9:00-10:30 AM (1.5 hours)

People Who Attended:

Alex Magnuson, Seth Peterson, Dale Lawrence . Caitlin Coffey, Austin Sather, Tanner Boge, Joel Stevens. Thaying Vang, Avery Schams , Thomas Kujak

Tony Perry Meeting in AM:

Tony Perry brought up good point today in asking if it were possible to create a management device that would control the amount of energy the Bluetooth module uses.

Perhaps we could investigate devices similar to an accelerometer that would put our management interface to "sleep" when the person was sitting down and not moving. This would save a great deal of energy.

I think this is something we could build in on the hardware and software side. See link below:

https://learn.sparkfun.com/tutorials/accelerometer-basics/all

Research Meeting for Prosthetic Limb - Lemelson MIT InvenTeam submitted by: Austin Sather

Today the software team worked on figuring out our bigger picture. Mr. Foye gave us some good ideas on what to look at for the software end of the project. After that, Joel and I(Austin) worked on getting the Pi zeros working. I was able to get the UI onto the monitor. Next time, I will have to learn more about the Pi and the different components that it provides. I want to see how the GPIO pins work and a get a good idea on how the programming language(Python) works with said pins. Catlin researched programming languages for the app. She also looked at the feasibility of using Apple versus Google Play. She found that we are leaning more toward Google Play for the app. It is a one time fee of $25 and the acceptance is very quick and easy to do.

Hardware Journal Submitted by: Alex Magnuson

Today the hardware team learned about conservation and loss of energy, gears and energy conversions. There is a “budget” in energy production within our system because too much resistance would result in a change in the way of walking. The key forces include movement, force, velocity and feel. We should look into specific motors/generators and begin to get some numbers of how much power is produced at how many RPMs of the shaft. RPM can be calculated with a technique of painting half of the shaft one color and using a tachometer or other methods. In any process there is always energy lost normally in the form of heat so the more processes we have the more energy will be lost (gears, levers, generator, storage, conversion, battery). It was also learned that the more load there is on a generator the more energy is required to start the movement of the generator.

Tony Perry meeting with the team to answer questions.

Students working on the problem at a work night.

Hard at work?? :-)