Scruve logic in auto mission issue

Or_Shahar · January 17, 2025, 10:07am

Hello,
I’m looking for a workaround for the issue described here:

Copter/Rover: maintain speed even when waypoints are placed close together

opened 01:57AM - 27 Dec 24 UTC

Enhancement Copter Rover

Copter/Rover SCurves has a limitation where it only looks forward two waypoints …(e.g. the current waypoint and the next one) and for safety reasons it plans the maximum speed so that the vehicle can stop in time for the 2nd waypoint. This can lead to the vehicle unnecessarily slowing if the user places the waypoints close together. How "close" depends upon the WPNAV_ACCEL and WPNAV_JERK parameters. We could reduce the user experienced slowdowns by enhancing SCurves to look further ahead.

Is there a way to plan a route that combines spline waypoints with standard waypoints to avoid this issue?

Alternatively, are there specific parameters that need to be set in a particular mathematical relationship to mitigate the problem?

Even if it’s not possible to achieve a perfectly smooth route without stops, I’m seeking a workaround to enable autonomous missions similar to version 4.0.5 — without slowing down between points or stopping at sharp 90-degree turns.

Any advice or suggestions would be greatly appreciated!

amilcarlucas · January 17, 2025, 10:30am

WPNAV_ACCEL_C = 2 * WPNAV_ACCEL so that the cornering behaviour is mostly controlled by WPNAV_RADIUS AC_WPNav: ACCEL_C defaults to 2x ACCEL by rmackay9 · Pull Request #25928 · ArduPilot/ardupilot · GitHub

from file 47 on Correctly configure ArduPilot for your vehicles on your first attempt | MethodicConfigurator

amilcarlucas · January 17, 2025, 10:49am

Reading the stuff I posted would have helped a lot. And updating to 4.5.7 would help as well.

rfriedman · January 19, 2025, 9:44pm

He said in discord his org can’t update - The organization is on this version and it is difficult to make version updates.

4.3.7 was released 31st May, 2023. 1 year, 7 months ago. I don’t know if telling users to upgrade to the latest version is a reasonable approach when this really isn’t that far ago.

amilcarlucas · January 19, 2025, 9:59pm

So if a hotfix or backport is created, he can not update as well?

Software is not Port wine. It does not get better with age, and bugs do not disappear with age as well. Software is immutable, it remains the same!

He wants a different outcome, he needs a different firmware, or a different configuration. That is just logic. I told him what parameter to change.

rmackay9 · January 24, 2025, 7:40am

Hi @Or_Shahar,

Could you provide a log file showing the issue? I see in the Discord chat that you’ve mentioned that if the waypoints are any less than 200m apart that the vehicle slows down but this implies that the acceleration is set very very low so I’d like to check

rmackay9 · January 24, 2025, 12:47pm

Hi @Or_Shahar,

I’ve created a PR to update our Auto mode page with advice on “Common Problems” including not reaching the maximum speed and not cutting the corners enough. TBH, that’s all the advice I’ve got