Autopilot Track Following

[DotDun]

Originally Posted by RobbieW

The GP32 has variation built in and the inbound RMC messages captured by OCPN on Com1 have the same value in the appropriate message slot as the GP32.

WRT RMC, my experience with OpenCPN is that it can be a little finicky about putting the statement in the .ini file. OCPN reads the ini file on startup then writes it on shutdown. So if you edit the ini while OCPN is running, it won't work.

The sentence to add in the Settings section is:

[Settings]
AutoPilot NMEA Sentence Out=RMB;RMC

Since your GP32 is including magnetic variation in the RMC sentence, OCPN will pass that along to the AP.

[RobbieW]

Originally Posted by DotDun

...Since your GP32 is including magnetic variation in the RMC sentence, OCPN will pass that along to the AP.

Thanks, on rereading the thread I realised that I hadnt impemented the config file tweak when it was suggested earlier by tonyappuk. Got hung up on the sharing aspect of that append and didnt continue to the meat of it. With your help in pointing out the reason for adding RMC it makes more sense. It'll be tested later today when we leave Muros for wherever we decide to go (cruising is great isnt it)

[RobbieW]

Originally Posted by RobbieW

Thanks, on rereading the thread I realised that I hadnt impemented the config file tweak when it was suggested earlier by tonyappuk. Got hung up on the sharing aspect of that append and didnt continue to the meat of it. With your help in pointing out the reason for adding RMC it makes more sense. It'll be tested later today when we leave Muros for wherever we decide to go (cruising is great isnt it)

.. so results on the trip from Muros to Freixo are promising. On the first leg which we took slow the AP appeared to hunt as before, then we increased speed a bit, to about 4.5kts, and the AP settled down steering a straight line - more or less - on the second leg. Then the sea breeze kicked in and we started sailing so the AP came off.

[sgschwend]

So, speed is good.

Glad to hear it worked out.

My guess is that your AP assumes a higher boat speed and therefore uses a higher rate of compensation.

[Catlaf]

I have the same problem with unstable XTE. I found that the autopilot - Robertson AP11- is not receiving BWW (bearing waypoint to waypoint).
This means that the autopilot is just using the XTE for steering, and not the compass also as long as there is no bearing received.

I have had the same problem trying to control the autopilot direct from a Garmin GPS.

Is it possible to get Opencpn to send BWW to the autopilot?

Here is what the autopilot can receive -

Sentences: APB, APA, BWW, RMA, RMB,

RMC, VHW, VTG, VWR, XTE, XTR.

[DotDun]

Originally Posted by Catlaf

I have the same problem with unstable XTE. I found that the autopilot - Robertson AP11- is not receiving BWW (bearing waypoint to waypoint).
This means that the autopilot is just using the XTE for steering, and not the compass also as long as there is no bearing received.

I have had the same problem trying to control the autopilot direct from a Garmin GPS.

Is it possible to get Opencpn to send BWW to the autopilot?

Here is what the autopilot can receive -

Sentences: APB, APA, BWW, RMA, RMB,

RMC, VHW, VTG, VWR, XTE, XTR.

Your AP should be able to use APB and/or RMB for initial bearing to waypoint, and then use XTE to stay on the track.

[Catlaf]

Originally Posted by DotDun

Your AP should be able to use APB and/or RMB for initial bearing to waypoint, and then use XTE to stay on the track.

It is not possible to set up anything with regards to NMEA on the AP11 autopilot. There is a NMEA check menu, and it show that no bearing is received/understood.

So, I believe my question still is, can OpenCPN send BWW?
Are there any possibility to "configure" the NMEA output to the autopilot?

Thanks!

[tonyappuk]

I would have hoped that your A/P could derive all necessary info from RMB and RMC which can be made available from OpenCPN on the A/P output port. I can't find any specific reference to an NMEA sentence BWW but bearing to destination and course angle are both available using RMB and RMC.
Tony

[Catlaf]

I have been in contact with Pronav, and they say that the pilot should work fine if the unit receives APB and VTG...

(Must admit that I am on thin ice here, I am not very familiar with NMEA)

Thanks!

[DotDun]

Originally Posted by Catlaf

Here is what the autopilot can receive -

Sentences: APB, APA, BWW, RMA, RMB,

RMC, VHW, VTG, VWR, XTE, XTR.

The AP should engage/operate on RMB, RMC, and XTE.

You could have a magnetic deviation issue. Make sure that OCPN is passing RMC (I think that's optional) so that mag dev is getting to the AP.

The AP has a magnetic compass. IIRC, OCPN puts a 'true' bearing in RMB. Hence you have to give the AP the mag dev in RMC. Mag dev most likely will come from the GPS and be passed thru OCPN via RMC.

[tonyappuk]

In my researches (in trying to build my own A/P) I use this link for NMEA sentence definitions. NMEA data You may find it interesting but probably not very helpful. If your A/P is programmed to look for APB and VTG to find it's information to steer the boat, you are probably out of luck to use OpenCPN. Dave did provide a configure change to output RMC as well as RMB for another poster whose A/P was just using XTE, but I expect he would resist further configurations. APB and VTG seem to be rather Loran oriented and as such are probably not much used now. Is it possible that you can configure your A/P to use RMB and RMC? I see in an earlier posting you said it can receive those sentences and since RMB and RMC seem to give all necessary info why not use them? Hope this gabble helps a bit!
Tony

[Catlaf]

The sentences I described earlier was a copy and paste from the manual, but it does not say how it is interpreted by the ap.
There is unfortunately no way to "setup" the NMEA input on the ap.

[spiv]

Hello everyone,

I have used OpenCPN for a year to make routes and navigating with a USB GPS.

All my instruments (wind, depth, radar, AIS and AP) are Furuno, connected to a Navnet disply, but no charts.
The AIS and Radar are connected via a router and I should be able to connect the laptop to the same router, but I cannot.

So far, I have been steering the AP manually checking my route on the laptop with OCPN, not the best set up....

I have read this thread, but I understood about 1/2 of what has been said .

What I would like to achieve is:

1. feed into my laptop and OCPN: GPS position from the AIS GPS
2. AIS information
3. Radar (I believe a plugin will be developed in time)
4. Wind & depth; is that possible yet ???
5. Feed the AP route information so it will follow the route.

Would someone be so kind as to tell me what is possible at the moment and where I can find some step-by-step instruction on how to achieve it?


Acer laptop running Win7 64 Pro (3 USB ports)
Furuno instruments:
- Navpilot 711
- FI-50 series Wind, Depth etc.
- F50 class B AIS
- DRS4D Radar


Many thanks for reading so far....

[DotDun]

Originally Posted by Catlaf

The sentences I described earlier was a copy and paste from the manual, but it does not say how it is interpreted by the ap.
There is unfortunately no way to "setup" the NMEA input on the ap.

APB or RMB are the normal sentences to communicate BTW to the AP. Your AP lists support for these sentences. This implies it will work if either of these are sent by the CP.

Again, I believe you have a mag variation issue. If you send the AP a BTW in 'true' you must also tell it the mag deviation for the current location to it can calculate what magnetic bearing to steer to. Since mag dev most generally comes from the GPS, OCPN will repeat what the GPS sends in the RMC sentence to the AP. But, you have to tell OCPN to send RMC, it doesn't send it by default. There are threads that tell how to do this.

[DotDun]

Originally Posted by spiv

Hello everyone,

I have used OpenCPN for a year to make routes and navigating with a USB GPS.

All my instruments (wind, depth, radar, AIS and AP) are Furuno, connected to a Navnet disply, but no charts.
The AIS and Radar are connected via a router and I should be able to connect the laptop to the same router, but I cannot.

So far, I have been steering the AP manually checking my route on the laptop with OCPN, not the best set up....

I have read this thread, but I understood about 1/2 of what has been said .

What I would like to achieve is:

1. feed into my laptop and OCPN: GPS position from the AIS GPS
2. AIS information
3. Radar (I believe a plugin will be developed in time)
4. Wind & depth; is that possible yet ???
5. Feed the AP route information so it will follow the route.

Would someone be so kind as to tell me what is possible at the moment and where I can find some step-by-step instruction on how to achieve it?


Acer laptop running Win7 64 Pro (3 USB ports)
Furuno instruments:
- Navpilot 711
- FI-50 series Wind, Depth etc.
- F50 class B AIS
- DRS4D Radar


Many thanks for reading so far....

It would be much easier to buy charts for your NavNet MFD.

1) Furuno data on Ethernet is proprietary. Only Furuno products talk that language (or the Maxsea software).

2) You need NMEA 0183 to communicate with OCPN.

3) The Furuno MFD will output sensor data (except radar) via a NMEA 0183 port and OCPN can use this.

4) I'm not familiar with the Furuno AP, but I would guess it has a NMEA 0183 port that is capable of taking 0183 BTW/XTE from OCPN.

5) Obtain a NMEA 0183 decoder (Actisense NMEA Reader?) and USB/RS232 adapter and start learning about your system.