Logan Ranger Energy Management System for a Prosthetic Limb: Work Night 1.10.19

Work Night

Date: 1.10.19
Location: Logan HS
Time: 4:30-7:30
Students: Paige, Alex, Thomas, Seth, Austin and Tanner.
Goal: Wire in the generation system to the buck boost system and rectifier to see what we get for electrical output.

This was a great work night! For the first time we were able to bench test our charging systems with only one motor/generator on the limb.

We need to get a new "Buck Boost" chip as the one we had a missing pin and we could not solder it in properly. We are checking the electrical schematic to see if the missing pin will matter. It could be just an input or output we do not need. A new chip has been ordered, but it is back ordered until the end of January. For testing purposes we are using a Buck Boost Board which is a larger version of the Buck Boost surface mount chip and is easier to mount and test for the students. When we create our final prototype, this board will not be used, just the chip.

Seth is updating the generator mount and has already printed another Heel Linkage Adapter for the heel that is curved to better fit the heel. We want to finish the new motor mount with the housing to protect the gears and then print it out to see how it specs out when mounted on the limb.

The software team has been making some strides moving from the hardware to the App we have created for phones. Still have some control issues and have to better define what we want the user to see and control on the phone. Austin is making an executive decision and moving to a different software to design the App.

We are still experimenting with turning motors into generators and changing the winding. Basically current increases with thicker wire and voltage increases with more turns in the winding. The limiting factor is the volume you have to places turns on the windings. As you increase the gauge of the winding wire, you can fit in more turns and you'll get more voltage but this comes at the cost of higher impedance and lower current capacity. A low gauge winding can support a higher current but at a lower voltage. This is really a balancing act.

Paige and Tanner worked on the Mid Term Grant Review presentation and time frame. Invitations will need to be sent out for this Feb 7th night.

This is a flow chart for our charging and energy management system.

This video shows a monumental step in our forward progress. It shows our conversion system (a Buck Boost board hooked up to a PS. If you look toward the bottom of the scope screen you will see a blue wave form suddenly spike up into the 5 volt range. This shows that it is taking a lower input voltage and through the use of inductors, increasing the voltage to a constant 5 V that we need to charge the battery. We later hooked this up to our energy storage system and within 5 steps on our tester we charged the capacitors to 50 V.