AC_WPNav: protect from divide by zero especially when using CH6 tuning of WP speed #18560
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We should take this opportunity to change the defines for stztic const. That is far better on debugging |
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On Fri, 3 Sep 2021, Pierre Kancir wrote:
We should take this opportunity to change the defines for stztic const. That is far better on debugging
I was going to mention that. Then I thought, "if they're used in one
place, just use them in one place". Then I thought, "this is better" and
approved it.
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Thanks for the review and comments. Let's merge this after Leonard's PR #18531 goes in. |
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Leonard's PR is in so merging this one too. |
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This PR includes a few cosmetic fixes to AC_WPNav:
.. and one real fix to avoid a divide-by-zero if ch6 tuning is being used to change the WP speed inflight. The reason the divide-by-zero could happen was that channel 6 tuning would call AC_WPNav::set_speed_xy() before AC_WPNav::wp_and_spline_init() was called. This means that _wp_desired_speed_xy_cms was still zero and led to the divide-by-zero.
This has been tested in SITL both before and after this change. Below is a screenshot of the ch6 tuning knob being used to set the WPNAV_SPEED value. Before this fix the simulator would crash and report the divide-by-zero.
This issue was discovered as part of the Copter-4.1.0-beta report, "Ch6 tuning of WP speed broken" on the 4.1 issues list and was reported here on the forums.