Update: Jason 2019-01-27

Short summary of this week

  • Verifying our flow torque disturbance data is reasonable by utilizing simulation

– Modified PC app simulation code, which enables .csv reading
– Torque input capability in the code so that I could use experimental torque data as an input in the simulation
– Confirmed that simulation matches well with the experiment

  • Checking a reliability of our current hot wire data

– Highly assumed that our current hot wire is broken. Not sure whether it was initiated from the broken electronics.
– Cheap  anemometer (fan-type) is not accurate compared to the teaching anemometer (hot-wire type) values;
fan-type: min: 1.5 [m/s], max: 6 [m/s]
hotwire-type (more accurate): min: 2 [m/s], max: 10 [m/s]

  • Building a  new miniquad with Karan

– Building it a first time took around 7 hours
– Currently it is not working and re-soldering is required (currently solder is almost impossible to use; currently waiting for new soldering tips)
– Took a time-lapse video; might be helpful for beginners

1. Torque disturbance verification

We are in the process of verifying that whether our estimated flow disturbance \hat{\tau}_{des} can be approximated to the true disturbance \tau_{dist}. Overall block diagram of given system is shown in Fig 1.

Fig 1. Block diagram of given system (true dynamics)

Problem is \tau_{dist} is unknown in the experiment. For this reason, I took disturbance estimate \hat{\tau}_{des} as an input in the simulation, and compared to resulting disturbance \hat{\tau}_{sim,des}. Detailed procedure is shown in Fig 2.

Fig 2. Purpose of using simulation

As it is given in Fig 3. the simulation result is very close to the experimental data. Especially, if you see the third plot, the only difference is experimental data shows more noise, which is expected.

 

Fig 3. Simulation results and comparison to experimental data (Fan is on after ~25 [s])

2. Hot wire reliability

Fig 4. Teaching anemometer

As I reported in previous posts, our hot-wire and/or electronics are mal-functioning. Currently, voltage reading of hot-wire has stopped working, so we need to find an alternative.

Although we purchased a new fan-type anemometer, reliability of the anemometer is unclear. A better candidate can be a teaching anemometer, since it is more accurate, well calibrated, more compact than hot-wire+electronics set-up.

From the result, I figured out that current hot-wire is not accurate;

Hot wire data : max: 17 [m/s], min: 6 [m/s]
fan-type: min: 1.5 [m/s], max: 6 [m/s]
Teaching anemometer (most accurate): min: 2 [m/s], max: 10 [m/s]

Therefore, we can conclude our nozzle cannot produce the flow speed of what we expected, and we need to increase [rpm] in future experiments.

Problem now is I cannot borrow it for a long term, since it must be used for classes. I want to discuss this further in our future meeting.

3. Building a miniquad

I built a new miniquad with Karan, since it is our first time to build a quadcopter. I am planning to build one by purely myself, once we  build one successfully. Although we were able to build a miniquad, it is not working now. We have checked ESCs, and they looked fine. We believe that soldering can be the issue, and planning to continue once the new solder tip is ready.

Meanwhile, we took a time-lapse video of building a miniquad, since video is more intuitive for beginners. A sample link is attached.