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Wind mode display + tack function
#1
I could test pypilot and so far it is working very well. I am still struggling with fine tuning of the gains.
In wind mode I do not like the 0 to 360° display. Wind mode I usually use when going upwind. I think it would be nicer to have 0 - 180° positive to stb and negative to port to avoid calculating the angle when wind is from port after a tack. Also the course setting should be according the direction the boat shall move.
One feature I am missing is a tack function. As I am sailing single handed very often I liked the tack button with adjustable delay of my old autopilot. Just push the button and time for handling the jib sheet.

Regards,

Kalle
  Reply
#2
(09-11-2018, 11:13 AM)kalle Wrote: I could test pypilot and so far it is working very well. I am still struggling with fine tuning of the gains.
In wind mode I do not like the 0 to 360° display. Wind mode I usually use when going upwind. I think it would be nicer to have 0 - 180° positive to stb and negative to port to avoid calculating the angle when wind is from port after a tack. Also the course setting should be according the direction the boat shall move.

Are you using the opencpn plugin? I agree that 0-360 is confusing for wind. I should as you say, change it for 0-180, but what is the best way to show which tack? Different color? Text? Dial?

As for the course settings. Are you referring to the direction reversing in wind mode? I corrected this in the latest pypilot plugin in git.
Quote:One feature I am missing is a tack function. As I am sailing single handed very often I liked the tack button with adjustable delay of my old autopilot. Just push the button and time for handling the jib sheet.

Regards,

Kalle

I am already automatically tacking. From the config you can add buttons for any degree you want. I put 110 degree buttons and it works for tacking if the feed forward gain is correct, the PR gain high, and small amount of P gain.

Now, I agree that some specialized tacking logic would be nice. Tacking on autopilot is limited by the rate the driver can move the rudder, so it won't tack as quickly as a human or always prevent overshooting as well, and with enough waves it can get confused. Some boats cannot tack properly with the limited rudder range of the autopilot, and you need to backwind the headsail to tack under autopilot. This results in a tack which nearly stops the boat.

For different conditions, tacking can be really different, so it is difficult to get the autopilot to tack well. I would like to add specialized logic to improve this, but then it becomes like the gains... difficult for users to tune.

How did the adjustable delay work? Did it go hard-over, wait a certain time, then move back? This may work, but again it will likely overshoot, and is not going to always make perfect tacks.
  Reply
#3
(09-13-2018, 10:59 AM)seandepagnier Wrote:
(09-11-2018, 11:13 AM)kalle Wrote: I could test pypilot and so far it is working very well. I am still struggling with fine tuning of the gains.
In wind mode I do not like the 0 to 360° display. Wind mode I usually use when going upwind. I think it would be nicer to have 0 - 180° positive to stb and negative to port to avoid calculating the angle when wind is from port after a tack. Also the course setting should be according the direction the boat shall move.

Are you using the opencpn plugin?   I agree that 0-360 is confusing for wind.   I should as you say, change it for 0-180, but what is the best way to show which tack?  Different color?  Text? Dial?

As for the course settings.   Are you referring to the direction reversing in wind mode?   I corrected this in the latest pypilot plugin in git.
Quote:One feature I am missing is a tack function. As I am sailing single handed very often I liked the tack button with adjustable delay of my old autopilot. Just push the button and time for handling the jib sheet.

Regards,

Kalle

I am already automatically tacking.   From the config you can add buttons for any degree you want.  I put 110 degree buttons and it works for tacking if the feed forward gain is correct, the PR gain high, and small amount of P gain.

Now, I agree that some specialized tacking logic would be nice.   Tacking on autopilot is limited by the rate the driver can move the rudder, so it won't tack as quickly as a human or always prevent overshooting as well, and with enough waves it can get confused.    Some boats cannot tack properly with the limited rudder range of the autopilot, and you need to backwind the headsail to tack under autopilot.  This results in a tack which nearly stops the boat.

For different conditions, tacking can be really different, so it is difficult to get the autopilot to tack well.   I would like to add specialized logic to improve this, but then it becomes like the gains... difficult for users to tune.

How did the adjustable delay work?   Did it go hard-over, wait a certain time, then move back?   This may work, but again it will likely overshoot, and is not going to always make perfect tacks.

Sailing upwind I have an apparent wind angle of about 36°. After the tack I want to have the same angle on the other bow. On my simple arduino autopilot I just changed from stb (+36°) to port (-36°). It was working but I only tried it on flat water and my boat is very heavy. On ther boats and condition this can of course be different. On my Navman autopilot you could preset a Tack angle for example 100°. Doing it like that you will have more rudder reaction. After reaching the new desired angle the autopilot should start steering to that angle. The boat will overshoot a little bit but good for taking up speed. That could be a simple solution.
The tack delay on the Navman was simply the time between pushing the button and starting the tack, time to go to the winch.
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#4
Quote:Sailing upwind I have an apparent wind angle of about 36°. After the tack I want to have the same angle on the other bow. On my simple arduino autopilot I just changed from stb (+36°) to port (-36°). It was working but I only tried it on
Do you suggest it display wind angles as + and - for starboard and port then?

Quote:flat water and my boat is very heavy. On ther boats and condition this can of course be different. On my
 It is not hard in flat water with a heavy boat in steady winds.

tacking in all cases the best way possible is difficult.  

For this reason, I think there need to be parameters specifically for tacking that are tuned otherwise the autopilot needs to learn from its mistakes, and this is even harder.

Quote:Navman autopilot you could preset a Tack angle for example 100°. Doing it like that you will have more rudder reaction. After reaching the new desired angle the autopilot should start steering to that angle. The boat will overshoot a little bit but good for taking up speed. That could be a simple solution.
As I said before, it already supports this.   You can add angles like 100 (I use 110 in stronger wind) to the button angles in the plugin.   The autopilot itself doesn't have a concept of tacking, only course changes, but it probably should understand tacking specifically.
Quote:The tack delay on the Navman was simply the time between pushing the button and starting the tack, time to go to the winch.
Nice idea.  Could also have a max turn rate for tacking.

so settings:
1) tack angle.   In wind mode it is automatically determined from current course
2) tack delay.  how long to wait to tack after hitting button
3) tack speed  how quickly to tack
4) tack complete... when to revert back to normal filter.  Typically half the tack angle but adjusting this would be useful to prevent overshoot.

 basic idea when you hit tack:


1) wait tack delay (setting #2)
2) change course to tack angle (setting #1) or opposite wind angle
3) move rudder at tack speed (setting #3) until it hits end of travel, or boat is through the wind (setting #4)

Once the boat is through the wind it would revert back to the normal filter which will move the rudder back toward the center from the gyro gain.

Not sure if this is the best way to do it, but it's an idea, I should try it out next week.   What do you think?
  Reply
#5
(09-14-2018, 04:20 PM)seandepagnier Wrote:
Quote:Sailing upwind I have an apparent wind angle of about 36°. After the tack I want to have the same angle on the other bow. On my simple arduino autopilot I just changed from stb (+36°) to port (-36°). It was working but I only tried it on
Do you suggest it display wind angles as + and - for starboard and port then?

Quote:flat water and my boat is very heavy. On ther boats and condition this can of course be different. On my
 It is not hard in flat water with a heavy boat in steady winds.

tacking in all cases the best way possible is difficult.  

For this reason, I think there need to be parameters specifically for tacking that are tuned otherwise the autopilot needs to learn from its mistakes, and this is even harder.

Quote:Navman autopilot you could preset a Tack angle for example 100°. Doing it like that you will have more rudder reaction. After reaching the new desired angle the autopilot should start steering to that angle. The boat will overshoot a little bit but good for taking up speed. That could be a simple solution.
As I said before, it already supports this.   You can add angles like 100 (I use 110 in stronger wind) to the button angles in the plugin.   The autopilot itself doesn't have a concept of tacking, only course changes, but it probably should understand tacking specifically.
Quote:The tack delay on the Navman was simply the time between pushing the button and starting the tack, time to go to the winch.
Nice idea.  Could also have a max turn rate for tacking.

so settings:
1) tack angle.   In wind mode it is automatically determined from current course
2) tack delay.  how long to wait to tack after hitting button
3) tack speed  how quickly to tack
4) tack complete... when to revert back to normal filter.  Typically half the tack angle but adjusting this would be useful to prevent overshoot.

 basic idea when you hit tack:


1) wait tack delay (setting #2)
2) change course to tack angle (setting #1) or opposite wind angle
3) move rudder at tack speed (setting #3) until it hits end of travel, or boat is through the wind (setting #4)

Once the boat is through the wind it would revert back to the normal filter which will move the rudder back toward the center from the gyro gain.

Not sure if this is the best way to do it, but it's an idea, I should try it out next week.   What do you think?
I agree it should work this way. Good idea, with settings #3 and #4 it can be adjusted to every kind of boat. Remember when tacking by hand we first give full rudder and turn it back when boat is through the wind at an definite angle.
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