Update: Clark 2018-12-07

1. Updates Summary
  • Tested and confirmed that UAUV is being controlled underwater.
  • Estimated the tracking error and depth estimator error with experiment.
2. Detailed updates

Setup of Experiment:

UAUV was commanded to hover at underwater at different depth in a large plastic box. Videos of hovers were taken with GoPro to visually measure the hover height underwater. The result was then compared to vehicle’s depth estimator outputs to analyze the vehicle estimation/tracking error.

Experiment Result:

Scenario 1: Command Z = 0.15m

Figure 1. Estimator Output of UAUV Underwate Hover with Command Z = 0.15m

Figure 2. Enlarged Position Estimator Output with Command Z = 0.15m

Figure 3. GoPro Screen Shot of UAUV Underwate Hover with Command Z = 0.15m

Scenario 2: Command Z = 0.10m

Figure 4. Estimator Output of UAUV Underwate Hover with Command Z = 0.10m

Figure 5. Enlarged Position Estimator Output with Command Z = 0.10m

Figure 6. GoPro Screen Shot of UAUV Underwate Hover with Command Z = 0.10m

 

Scenario 3: Command Z =0.05m

Figure 7. Estimator Output of UAUV Underwate Hover with Command Z = 0.05m

Figure 8. Enlarged Position Estimator Output with Command Z = 0.05m

Figure 9. GoPro Screen Shot of UAUV Underwate Hover with Command Z = 0.05m

Scenario 4: Command Z =0.02m

Figure 10. Estimator Output of UAUV Underwate Hover with Command Z = 0.02m

Figure 11. Enlarged Position Estimator Output with Command Z = 0.02m

Figure 12. GoPro Screen Shot of UAUV Underwate Hover with Command Z = 0.02m

Analysis of the Result:

From the test, we observed that the vehicle hovered at different depth with different command input, confirming that the system is being controlled underwater.

Meanwhile, we observed that for the current control algorithm, the system has a 0.05m tracking error. During the hovers, estimator would give a height that is 0.05m higher than indicated.

We also found that the major error of the system stemmed from depth estimator. I believe the error was caused by an erroneous attenuation rate of the shell that is hard coded into the system. The value was obtained in an experiment a month ago and I didn’t count the temperature change factor during that experiment. I will do a new round of experiment and update the rate. Hopefully it will fix the error.

Link to Test Videos:

https://drive.google.com/file/d/1XMd_vfEg_-fw12EKhz1P5jNwdoTYLGDf/view?usp=sharing

3. Planned work for next week

As next week is the final exam week, I am writing down here my planned work for the next two weeks.

  • Fix the estimator error
  • Autonomous Water Breaching Test (Write a program that can detect the status of the drone and enables it to shift between underwater and in air mode.)
  • (Reach Goal) Study the wave breaching algorithm and recreate it in C++