This week, I focused on three different things
- Analyzing experimental torque disturbance data and its comparison to simulation
- Preparation and presentation for a meeting with a potential sponsor
- Preliminary velocity data analysis using CTA (constant temperature anemometer)
1. Torque disturbance data analysis
I started analysis on torque disturbance data. I had fixed a bug in my python script, which caused a huge order of magnitude for the disturbance torque. Although the order of magnitude became more plausible, still we have an issue with the result.
Fig. 1. 1. X-direction torque 2. Y-direction torque 3. Z-direction torque (with fan on)
Problem is that there is a very small lag between the disturbance torque and the motor torque. Since the command torque is proportional to the error of angular velocity (), we would expect some lags. However, the level of lag is very small, as it is shown in the graph. I looked at Karan’s data, and similar level of small lag was observed.
In order to figure out the reason, I ran a simulation with a torque input (10 [mNm], x-direction only) from 27-31 [s], and results are shown.
Fig 2. Simulation results with a torque input (Position, velocity, angular velocity, and motor forces)
Fig 3. Torque results, x-direction (enlarged)
Fig 4. Torque results, overall
However, as one can see from the position plot, I was adding too much torque input, which resulted in very high magnitude of the torque.
I will try to make a similar simulation of our experiment, to properly compare the results with our experimental data next week.
2. CTA preliminary test
I also started collecting velocity data of the jet utilizing CTA. As an initial stage, I manually hold the sensor and measured center-line velocity.
Fig 5. Flow velocity measurement description
Results are as follows;
Fig 6. Jet velocity w.r.t time.
- While I will need further analysis of the experimental data, for example, I have noticed that the voltage of hot-wire circuit is not consistent. I will need to conduct further experiment to figure out the consistency of our sensor.
- Also, I will compare the experimental jet velocity with theoretical values, and see whether there is a self-similarity as well.
This week, I have learned that
- Thorough, logical way of analyzing/reasoning the given data
- Utilizing/connecting the knowledge that I have learned from the class
Next week (Specifically, before the general progress meeting Dec/19, considering my hectic schedule on finals/project) I am planning to finish the tasks that I stated Section 1 and 2.
In a month, I will finish the flow characterization on drone so that I can aim the results to upcoming conferences.