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ArduPilot / MissionPlanner

Mission Planner Ground Control Station for ArduPilot (c# .net)
http://ardupilot.org/planner/
GNU General Public License v3.0
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Feature request - sum of segment lengths #1134

Open charleslinquist opened 8 years ago

charleslinquist commented 8 years ago

I fly mostly autonomously. And although Mission Planner gives me the length of the segments between each waypoint, it doesn't sum them. It would be nice if the total length of all segments was shown at the bottom of the list of waypoints. That way, I would be less likely to send the craft further than it could safely go.

Better yet would be a warning when the total length of the segments exceeded a user-set value, and even better would be a rough approximation of how much battery life would be consumed by the time it reached each waypoint. Climbing and descending battery usage could be estimated to come up with a more accurate figure.

meee1 commented 8 years ago

in flightplanner in the top left there is a total of the planned mission, is that not what you are looking for?

also in flight data the bar at the top of the map with the yellow dots?

charleslinquist commented 8 years ago

I apologize! I didn't see that there.

But I do have what I think is a legitimate request:

Filter the current reading through an averager or smoother. The current readings bounce around so much they are difficult to interpret. You could give the user a choice as to the degree of smoothing, so they could still see narrow spikes if they want to.

Also, the DROOP parameter is not well documented. I don't know what it is supposed to be, but if it is supposed to be an indicator of the
battery ESR, I don't know how it is used. And if it really isn't used, it could be changed into a "corrected" battery voltage.

Most LiPos have an ESR of around 6 milliohms per cell. Using that figure, a four cell battery loses 24mV per Amp in that ESR, so the actual cell voltage is higher than the terminal voltage by that much. The curves I find on line that show discharge voltage vs. current would indicate that the lower voltage at higher current draw is nearly 100% explained by simply considering the ESR of the battery.

At 30A, the voltage reading of a 4 cell battery is 0.72V low (terminal vs cell), so the voltage could be adjusted upward by the smoothed current, thereby giving a more accurate indicator of battery condition. My readings show that a figure of 6 milliohms per cell is close to what the average new battery has. As the battery ages, the ESR goes up and the error increases. Defaulting to 6 milliohms/cell is a good starting point, and if the user wanted to change that, they could.

I realize that the right place for this adjustment is in the controller, but nonetheless, providing this "corrected" reading as well as the value provided directly by the controller is just one more data point. To me, battery condition is probably the most important factor in flying. The program could even dynamically calculate battery ESR by looking at voltage at two closely spaced intervals while at the same time watching the current. If the current changed by 10A or more within a few seconds, the voltage before and after the change could be noted and the ESR calculated.

Charles Linquist

Check out my multirotor blog at http://calmultirotor.com

On 2/13/2016 12:14 AM, Michael Oborne wrote:

in flightplanner in the top left there is a total of the planned mission, is that not what you are looking for?

also in flight data the bar at the top of the map with the yellow dots?

— Reply to this email directly or view it on GitHub https://github.com/diydrones/MissionPlanner/issues/1134#issuecomment-183624353.