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})