Tome of Finite Knowledge

MAVExplorer Log Analysis

2 min read

MAVExplorer, part of the MAVProxy package, is a very capable dataflash log analysis utility for advanced users.

Launch via MAVExplorer.py once the MAVProxy package is installed. It should be available on the system PATH. The primary means of interaction is via a command-line console, prompting as MAV> .

See also

Graphing data

Graphs can be arbitrary Python expressions, using not only log data entries but also functions from the math module and some MAVProxy functions as well (like what??). Separate multiple expressions by a space character to plot multiple at once.

  • graph RATE.Y RATE.YDes: Plot the desired rate and actual rate of the yaw axis.
  • graph PIQY.FF+PIQY.P+PIQY.D: Plotting a given expression.
  • graph PIQY.FF+PIQY.P+PIQY.D 0.2*PIQY.Act: Plotting multiple expressions.

Checking parameters

You can check parameters with the param command and a regex-ish syntax. The docs say “regex”, but it acts like more of a glob.

  • param: List all parameters and their values.
  • param Q_A_RAT_YAW_*: List all the parameters starting with Q_A_RAT_YAW_.

MagFit Compass Calibration

MAVExplorer is home to the best (in my experience) compass calibration calculator and compass-motor offset calculator, especially if you have a current monitor on the vehicle. It analyzes a log (the more “yaw-y” the log, the better) and produces a set of compass parameters for you to use on the vehicle.

Ensure you have the scipy Python module installed!

  1. Launch MAVExplorer
  2. From the GUI, select Tools ⇒ MagFit
  3. Enter the options as desired
  4. Click “Run”

The graph will indicate how effectively the MagFit algorithm was able to determine correction values, and the parameters to set will be printed to the console.

Graph View

Backlinks