Today I spend the most part of the time out flying the Skywalker. I am almost certain I have found the cause of the problem of my Fy-31AP with its RTH and ACM mode. A summary:

Today I flew with 4 batteries. The conditions today were windy with quite strong gusts. I have all my PID settings set to default. The pots for the aileron gain set quite high. I reset the travel of my ailerons to their maximum. On the first flight the RTH and ACM functions worked every time. The plane came home and was not blown down wind. I tested it upwind, downwind, and making it have to fly across wind to home. Every time it worked very well, especially considering the conditions, it was fairly gusty at times.

Then for the second, third and fourth flights, RTH and ACM didn't really work. It entered its tight circling and never came home. Always getting further away and requiring me to take over. However, on the last battery of the day I noticed something important. I am using the hornet OSD. I notice the number of satellites would fluctuate quite a lot during the tight turns. It went from 11 down to 8 then when really bad 6 and even 5. Not sure if this was because of the tight banking. I then continued to watch. The information being displayed was inaccurate. It was like it had a significant delay. I flew the plane home and then flew it low and fast around me so I could monitor the information. I found the GPS to have a significant delay in its data. I would head north for about 100 to 150m and it would still say I was still heading south. The distance from home was wrong, it was also suffering from the same delay. Here is a link to this video (it even has a crash at the very end when another plane clipped the skywalker and knocked off the HD camera.)

A video showing a problem with the auto pilot with GPS lag. (12 min 26 sec)

Now at home I have reviewed the videos. The recording from the first flight differs from all the other flights. The GPS data is correct. When I head south, it reports I am going south. The distance is also correct. It also seems the update speed is much faster. This is the video of every time I try RTH or ACM it works.

So it seems there is a problem somewhere with my GPS. It gets a lot of satellites but the update speed to the OSD and I assume the FY-31AP is very slow. Perhaps there is some noise due to the wiring? So I know the system does work and very well. My problems don’t seem to be control system related after all.

Also when reviewing the videos of when the GPS data is incorrect I see the update speed is too slow for the plane to make a decision to come home. It’s already turned away before it realises it’s coming closer due to the GPS lag.

One thing to note is I did not change any settings on the FY-31AP today. Only thing that changed between the working and non-working times was the battery and a possible disruption to the wiring as a result of the two battery change outs.

Any Ideas? Seems I might not be far from solving my problems.

Integr to solve this problem we need to control NAV gains settings like in Ardupilot(diydrones), because default settings is to low. Hey feiyutech can you hear us? can you add Navigation gains in GSC? Please.

flew my bixler2 today in high winds for the first time. It has been working fine in calm conditions but this time when I use stabilization or rtl it banks left and does a dive . What is quite interesting though is when its on the ground before a flight and I turn on stabilization its fine but then after landing it and turning on stabilization the ailerons bank hard left and gradually after about 10 secs the ailerons come back to level. Any ideas?

Spent another few hours trying to solve my RTU and ACM problems. Watched a few older videos and found also when the tight circling was happening the GPS didn't really know where it was. The compass was pointing in the same direction while it was doing the circles.

Yesterday I played with the GPS and found that even if you have a lot of satellites that doesn't mean you have accurate data. I found I could put the GPS in the middle of my skywalker and it would get 11 satellites. But there was a significant lag of a few hundred meters before the GPS updated the compass etc. I moved it around until I put it on top of my main battery far away from all the other electronics. I found there was no GPS lag. A sharp fast turn and the compass would update instantly and correctly. I then proceeded to keep moving the GPS around. Same number of satellites but the lag returned. Placing it back on top of the battery and the lag problem would disappear. I tested this a number of times over and over to make sure.

With the lag RTH would not work, rather doing the tight circles. Without the GPS lag, RTH worked every time even in the strong wind. It was very good, doing tight 180 turns to point home and immediately correcting if blown off course.

Saabguyspg, where do you place your GPS in your skywalker? I am thinking to make an extension cable for it and place it to the rear of the plane.

my gps is always placed far away from all other noise (power lines, data modem and video TX)

my GPS is usually out on the tail boom of the skywalker, video TX up on the tail for my Panda

For my 31AP it's under the wing in that compartment with the 31AP itself, video TX up on the tail.

I have read some people having issues with the stock etention cable for the gps.. so maybe best to make your own and solder it (don't use the plugs for an extension)

good job in finding your problem!!! and great info for others if it works!

Steve

Yak13.... can you tell us which firmware you were using?

Perhaps the problem was due to another issue... radio glitch???

Can you describe the rest of the system, ESC, BEC, Rx.....

Who did you say you worked for?

Originally Posted by Integratedneck

Spent another few hours trying to solve my RTU and ACM problems. Watched a few older videos and found also when the tight circling was happening the GPS didn't really know where it was. The compass was pointing in the same direction while it was doing the circles.

Yesterday I played with the GPS and found that even if you have a lot of satellites that doesn't mean you have accurate data. I found I could put the GPS in the middle of my skywalker and it would get 11 satellites. But there was a significant lag of a few hundred meters before the GPS updated the compass etc. I moved it around until I put it on top of my main battery far away from all the other electronics. I found there was no GPS lag. A sharp fast turn and the compass would update instantly and correctly. I then proceeded to keep moving the GPS around. Same number of satellites but the lag returned. Placing it back on top of the battery and the lag problem would disappear. I tested this a number of times over and over to make sure. BTW I used the extension cable that came with the FY31AP to relocate the GPS.

With the lag RTH would not work, rather doing the tight circles. Without the GPS lag, RTH worked every time even in the strong wind. It was very good, doing tight 180 turns to point home and immediately correcting if blown off course.

Saabguyspg, where do you place your GPS in your skywalker? I am thinking to make an extension cable for it and place it to the rear of the plane.

I had the EXACT same problem. I relocated my GPS on top of the wing at the front and it has worked fine. Before that I had it below the wing in the upper compartment. I think the carbon fiber wing spars interfere with the GPS signal.

Has anyone had problems during firmware updating??? I am trying to update the firmware to the latest version... but I cannot get "connection success"

I understand that if the updating goes bad, the fy-31 can be internally damaged...

For me, I install the updater downloaded from Feiyu, install it to the desktop, insert the USB cable and connect to the correct port (after verifying the port address)

Then nothing. The fy-31 is lit up, but the software does not "see" the device, or give me "connection success" so I can't update the device, or even check the version installed.

Put the unit back in the plane, seems to work fine, no changes. I have had the same problems with my fY-30A... so it is likely something I am doing wrong....

any suggestions??

Originally Posted by simplyfly

Has anyone had problems during firmware updating??? I am trying to update the firmware to the latest version... but I cannot get "connection success"

I understand that if the updating goes bad, the fy-31 can be internally damaged...

For me, I install the updater downloaded from Feiyu, install it to the desktop, insert the USB cable and connect to the correct port (after verifying the port address)

Then nothing. The fy-31 is lit up, but the software does not "see" the device, or give me "connection success" so I can't update the device, or even check the version installed.

Put the unit back in the plane, seems to work fine, no changes. I have had the same problems with my fY-30A... so it is likely something I am doing wrong....

any suggestions??

Which version are you trying to update to? 1.2? Those cables are famous for going bad. I had to resolder all the joints on mine to get the computer to recognize it again.

Originally Posted by simplyfly

Has anyone had problems during firmware updating??? I am trying to update the firmware to the latest version... but I cannot get "connection success"

I understand that if the updating goes bad, the fy-31 can be internally damaged...

For me, I install the updater downloaded from Feiyu, install it to the desktop, insert the USB cable and connect to the correct port (after verifying the port address)

Then nothing. The fy-31 is lit up, but the software does not "see" the device, or give me "connection success" so I can't update the device, or even check the version installed.

Put the unit back in the plane, seems to work fine, no changes. I have had the same problems with my fY-30A... so it is likely something I am doing wrong....

any suggestions??

How many comm ports do you have displayed on your computer?

I have about nine and I just tried each one on the list, I think number eight done it for me. The first couple connected but didn't bring up the "success" message.

But if it's working fine, don't bother changing it for sake of change.

Originally Posted by simplyfly

Has anyone had problems during firmware updating??? I am trying to update the firmware to the latest version... but I cannot get "connection success"

I understand that if the updating goes bad, the fy-31 can be internally damaged...

any suggestions??

I had this problem. It was a bad USB-TTL cable. I think it's pretty common. Had mine replaced and it has worked fine since.

Originally Posted by daronj

I had this problem. It was a bad USB-TTL cable. I think it's pretty common. Had mine replaced and it has worked fine since.

likely the cable... I'll replace it and try again... Now I have a new problem

The Hornet OSD shows the data from the current sensor, but no attitude, compass or GPS data

Everything is static, when I move the plane, no adjustment of my compass.. nothing. The unit also shows that I am in RTH, when I am not. I can still switch the modes with my Tx. Just doesn't show it on the OSD.

everything seems to be good with the 31, I can see and hear the mode switch from RC to ABM... and read the blue light... works perfect. Must be the OSD... bummer.

I'll have to go over all the wires.... also can't get my data modem to connect with the GCS... but that isn't anything new

Is it possible to change the Hornet OSD from displaying metric and show imperial measurement instead?

Originally Posted by saabguyspg

my gps is always placed far away from all other noise (power lines, data modem and video TX)

my GPS is usually out on the tail boom of the skywalker, video TX up on the tail for my Panda

For my 31AP it's under the wing in that compartment with the 31AP itself, video TX up on the tail.

I have read some people having issues with the stock etention cable for the gps.. so maybe best to make your own and solder it (don't use the plugs for an extension)

good job in finding your problem!!! and great info for others if it works!

Steve

I thought my problem of elevons going full deflection when engaging RTH or ACM was solved, but I'm pretty sure I had about 11 satellites at the time. Now I can only get 6 maximum and my troubles have returned. I haven't changed anything on my wing and I'm keen to see if lack of satellites is my problem.

My question is what type of wire do you use to extend the GPS? Is servo wire ok to use?

When mounting the GPS location is important. It is probably best to locate it on the top of the aircraft. The wire between the GPS and any other device should NOT be ribbon cable. The wires should be carefully twisted or braided to reduce inductive pickup from other RF devices. If you can make a ground plane under the device it MAY help. A ground plane could be made of PCB blank from an electronics store. or a cut up old PCB that has a large blank area.

Also other devices on the aircraft may have to be shielded by an RF shield between the device and the GPS. RF shields can take many forms. Start with aluminum foil as a cheap test. Copper screen can be used and is easy to solder. An alternative is copper foil on leads, or copper foil coated card stock, which you can cut with scissors and make into a box around devices. You may have to put RF chokes on various leads on devices. These look like black dough nuts or cylinders.

I suspect if you place the GPS as far from the other devices as the included cable permits, that you will have better results. Test all of these options on the ground.