Week 2

      This week was the first time we had a Monday class meeting for capstone. We confirmed our budget with Dr. Gordon (it is $600) and updated him on the progress of our project. Max Murphy worked on Arduino code for the motor while the rest of the team went to Josh Park's office and created a 3D scan of the foot. This will be used to 3D print a foot/ankle "brace" that fits onto Isaac's leg.

Josh Park holding the 3D scanner to scan Isaac's foot.

It was found that wearing a sock made it difficult to complete and align the different scans, so the process was redone. The colored dots helped with alignment. 

An example of the 3D scan rendering.

This was the completed scan, which Josh sent us later in the week as an .STL file.

    Later in the week, we went to the shop again and constructed a new bracket for testing the motor. We also constructed a "shield" that will help stop anything that flies off during testing (if something should fly off). The force transducer is able to screw onto the side of the bracket, which will hopefully allow us to accurately measure the forces generated.

A sheet of metal was bent to fit over a 2x4 piece of wood. The motor will be mounted to the sheet metal.

Another view of the set-up. The motor is now mounted so that it will spin horizontally, rather than vertically.

The force transducer can be attached directly to the test bracket.

This is an example of how the set-up would be used during testing. The "shield" is open at the top as the weight would be unlikely to fly out of the top if the screw were to break. This also allows us to use the tachometer while the motor is running.

     We attempted to test out the motor; however, the screw we were using hit the side of the shield and broke. We placed an order with Dr. Gordon for a brass plate from McMaster-Carr. Once the brass arrives, we would like to go to the shop and mill out the following object.

The object we plan to mill out of the stock brass piece.

This object combines both the "arm" and the "weight" portion, so that we will no longer have to use a small M3 screw and mass. This should make the system much stronger and less prone to breaking/shearing off. The round end with holes in it is where the system will mount to the motor. Brass was chosen because it has a high density and is also able to be machined with our equipment. We are hoping to receive the brass early on during Week 4 and be able to mill out our shape, as most of our testing is at a stand-still until this step occurs.
     We also continued to work on the Arduino code that controls the motor, and also started discussing how we plan to attach the elastic bands to the harness. As of right now, we are planning on sewing the elastic bands; we will fold the elastic band over itself to create a loop. This loop would then allow the ban to be taken off the harness if need be. This will likely be delayed until further in the semester, however, as testing the motor is our number one priority for the time being.

Week 1(?); First Post of Second Semester

     This is the first week of class since Christmas break. Over break, we ordered parts for our project, which were waiting when school resumed. Below is a picture of the items we ordered.

The items ordered over Christmas break.

     We double checked that we received all of the items, and then started constructing the base plate in order to test the motor. We went to Wes' shop and got his help to do this. We bent a sheet of aluminum to create a 90-degree bend, and also punched holes into the metal in order to anchor the motor to the plate.

The above pictures show our team fabricating the test bracket in the lab.

     Once the test bracket was constructed, we began our motor testing. We started out by using a 50 mm screw and spinning it by itself at different speeds (increased incrementally). We then added a small mass and repeated the process, and slowly worked up to larger masses. The mass sets were threaded onto the screw via the hole in their centers. We used the tachometer to measure the RPM of each different combination. The motor was spun via an Arduino and motor controller (as shown on the order form), with much of the code being found/written by Max.

This shows the set-up with one of the smaller masses being attached to the motor.

The motor test bracket as shown from the back (held down by a clamp).

Using the tachometer to measure the RPM of the spinning mass. 

Max used Arduino code and a motor controller to control the motor's speed. 

The results from the testing can be seen in the picture below:

The "scary" sections were when the motor hit a harmonic and vibrated in a scary-fashion, which didn't allow for proper readings.

     We also met up to discuss our options for mounting the mass to the motor, as well as the motor system to the ankle. During our testing, we had found that the head of the 50 mm screw sheared off, launching the mass into the air. Obviously we do not want this, so we explored several alternative options for attaching the weights to the motor safely. Some ideas were using a bigger screw, welding a screw/rod to the motor, redoing the bracket to change the resonant frequencies, using a bike cable rather than screw, and machining out a solid piece that would serve as both the mass and the "arm." We felt that the last two ideas were the best, but we think that there will be difficulties with both options. Therefore, we are hoping to discuss them with our tech adviser and/or Wes before purchasing anything.

Ideas of how to attach the mass and motor configuration together. 

     For attaching the motor to the ankle/leg, we want something that is cost-effective (re: not expensive), but that also provides stability. Our current ankle brace would not be sufficient on its own as it would allow a lot of room for movement once the motor started spinning. Ideas we contemplated were 3D printing "shin guards" and then Velcro cinching them down, buying a sturdy boot (such as a ski boot or work boot), or purchasing a sturdier ankle brace. We believe we will try to 3D print material, as this would not count against our budget. However, we would again like to consult with both the tech adviser and Josh Park before making a decision.

Ideas of how to attach the motor configuration to the ankle.