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Old 04-03-2016, 07:27 PM   #1
jamisonchang
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Default GPS misadventure

Hello,

I finally felt that my Trex 600 was tuned in with the SK720 BE and wanted to test out the altitude hold function. Well, let's just say I now have about a 1/2 of my helicopter left. When I hit the altitude hold switch, the heli oscillating violently in the y-axis and then plowed itself into the ground. I set gain at 25%. I am willing to take the blame for this crash though don't know what I did wrong-- heli was flying well otherwise and vibes < 5.

I can rebuild of course however-- it seems the universe wanted to punish me further . .. . now, the GPS does not seem to want to get a position fix. The unit was on the tailboom and it's connection to the SK720 was broken abruptly (cable connecting them came out without breaking etc). When I hook up the to software:

I get that is is manual mode
Status is OK

I get a magnetic field reading and a heading. It seems to be seeing 5 satellites ( I think it saw more than this previously in same location) and acquires 3-4. I don't get a lat/long or a barometer reading-- no matter how long I wait. Of course, It is not on the tailboom-- I just but it on the same side of the heli close to where it was.

Is there a way to tell if the unit was damaged? Any thoughts on troubleshooting?

I don't mind a $100 crash but if the GPS was damaged, I don't know if I can bring myself to buy another given what happened.

Thanks
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Old 04-03-2016, 09:42 PM   #2
Skookum
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Please email us the log. Also, if the gps has a damaged antenna we may be able to fix it.
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Old 04-04-2016, 03:05 AM   #3
GaryDT
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Post Skookum SK720BE GPS2 Heli Crash

Below is a report of my flying session yesterday.

The three incidents below were with the GPS2 hard deck set to 9 metres. After flipping to upright (if required) I wasn’t completely sure whether the heli should hold its current position and increase the altitude to 9 metres, or increase the altitude and fly to the home position, since most of my testing was very close to the home position anyway. However for all three incidents, it seems the system was not doing either, but it did take control away from me, until I flicked the rescue switch back to manual.

Just to be clear, apart from the following three incidents, the rescue system seemed to be working quite well overall (and this is my 2nd session with the setup), other than the occasional height discrepancy at which times the rescue activated higher or lower than the set height. Higher wasn’t too bad obviously, but sometimes it activated at approximately 5 to 6 metres (set to 9 don’t forget), and this was with the heli quite gently descending through the hard deck. The rescue was very fast, but from inverted this still meant dropping about another meter or two.

It was myself and one very experienced pilot at the field doing the testing, and we concluded that it would be tricky to successfully use the setup to save a pilot from a loss of control during practicing 3D manoeuvres, since one can never predict how badly a pilot might lose control causing the heli to potentially fall through the hard deck very fast, and considering the height variation above and below the hard deck rescue set height at which the rescue activated, the height set would have to be at a guess 15 metres plus, and even then we were not left feeling confident. Also, if the turbulence from the nature of 3D flying interferes in any way with how the system performs the rescue, then this alone seems to contradict the statement quoted below.

Also please note: I bought three Skookum SK720BE GPS2 double combos with the intention that pilots could be rescued from practicing to fly 3D manoeuvres. The GPS2 product description does state “It can be flown slow and smoothly, or at full smack 3D

1) The heli was about 15 metres high as I was flying a rolling circuit, and then the rescue kicked in, but seemed to make no attempt to hold position or adjust the height (to adjust the height correctly it would have had to descend), as it very slowly flew off in the direction of the cafe. Next I flicked the rescue switch to manual and regained control. Not really a problem since it was so high. Perhaps the barometer was confused by the turbulence of the rolling (but I thought the GPS had a say in this, and the led was blue), and sensed it was at 9 metres when in fact it was much higher, but this doesn’t explain why the rescue position and height control wasn’t working. This is my 2nd session flying/testing with the setup. My vibration reading was 0.7 during flight for the last flight of my 1st session some days ago (I’m using the super soft anti vibration kit), and I’ve also never lost the GPS lock (I don’t think so anyway, since the led was always blue).

2) Whilst doing knife edge drops from upright and gradually increasing the amount the heli was rotated towards being at a knife edge orientation, the final almost completely knife edge drop caused the rescue to kick in again, as it had been, at approximately 9 metres (maybe even 2 to 4 metres lower than 9), but this time it didn't seem to make any attempt to hold position or gain height. It flew off to the right at a slow to steady speed and descent for about 3 seconds before I then hit throttle hold thinking it was going in, but at the last second I managed to flick the rescue switch to manual and level it out, with the blades having almost stopped, so I just managed to get away with it.

3) I was gently rolling from left to right and the rescue activated at about 9 metres, but again it seemed to make no attempt to hold or adjust the position, as it gradually descended and flew into the fence. I tried to stop it happening, but accidentally flicked into normal (idle) mode instead of flicking the rescue switch to the manual position (both switches are on the left), and for the 2 to 3 seconds until the heli hit the fence I was wondering why it wasn't responding. I reckon I probably hit throttle hold (the big switch on the right) at about the instant it hit the fence.

After incident 1) I should have perhaps landed and investigated, but I had my spotter with me, and we only tested the rescue system when there were no people or obstacles within or close to the flying area, which left me feeling confident enough that further testing would be okay, since in general the rescue was working most of the time. Even so, at least other users can read about my experience and learn from my mistakes, and hopefully not have it happen to them.

I haven’t looked at the logs yet, but I’ll post them on here when I get a chance. The units look completely unmarked, so I’m hoping they’re still okay.

Another report of this flying session can be found here: http://rcheli.club/sessions/view?sessionid=7494

Last edited by GaryDT; 04-08-2016 at 03:26 AM.. Reason: Session link added at the bottom of the page
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Old 04-04-2016, 05:39 AM   #4
jamisonchang
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Default Log, Vib only

Hi

Please find the log attached. Unfortunately, I don't think it will be too helpful as it was set to vibration only ( my mistake).

I turned the logging back on just in case it gives the status of the GPS. The others are vibration only
Attached Files
File Type: skv LOG31.SKV (93.5 KB, 28 views)
File Type: skv LOG1.SKV (805.5 KB, 21 views)
File Type: skv LOG13.SKV (605.5 KB, 19 views)
File Type: skl LOG15.SKL (109.5 KB, 24 views)

Last edited by jamisonchang; 04-04-2016 at 07:21 AM..
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Old 04-04-2016, 07:17 AM   #5
CZorzella
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Quote:
Originally Posted by GaryDT View Post
Below is a report from my flying session yesterday.

The three incidents below were with the GPS2 hard deck set to 9 metres. After flipping to upright (if required) I wasnít completely sure whether the heli should hold its current position and increase the altitude to 9 metres, or increase the altitude and fly to the home position, since most of my testing was very close to the home position anyway. However for all three incidents, it seems the system was not doing either, but it did take control away from me, until I flicked the rescue switch back to manual.

Just to be clear, apart from the following three incidents, the rescue system seemed to be working quite well overall (and this is my second session with the setup), other than the occasional height discrepancy at which times the rescue activated higher or lower than the set height. Higher wasnít too bad obviously, but sometimes it activated at approximately 5 to 6 metres (set to 9 donít forget), and this was with the heli quite gently descending through the hard deck. The rescue was very fast, but from inverted this still meant dropping about another meter or two.

It was myself and one very experienced pilot at the field doing the testing, and we concluded that it would be tricky to successfully use the setup to save a pilot from a loss of control during practicing 3D manoeuvres, since one can never predict how badly a pilot might lose control causing the heli to potentially fall through the hard deck very fast, and considering the height variation above and below the hard deck rescue set height at which the rescue activated, the height set would have to be at a guess 15 metres plus, and even then we were not left feeling confident. Also, if the turbulence from the nature of 3D flying interferes in anyway with how the system performs the rescue, then this alone seems to contradict the statement quoted below.

Also please note: I bought the units for the intention of pilots being rescued from practicing to fly 3D manoeuvres. The GPS2 does state ďIt can be flown slow and smoothly, or at full smack 3DĒ

1) The heli was about 15 metres high as I was flying a rolling circuit, and then the rescue kicked in, but seemed to make no attempt to hold position or adjust the height (to adjust the height correctly it would have had to descend), as it very slowly flew off in the direction of the cafe. Next I flicked the rescue switch to manual and regained control. Not really a problem since it was so high. Perhaps the barometer was confused by the turbulence of the rolling (but I thought the GPS had a say in this, and the led was blue), and sensed it was at 9 metres when in fact it was much higher, but this doesnít explain why the rescue position and height control wasnít working. This is my second session flying/testing with the setup. My vibration reading was 0.7 during flight for the last flight of my first session some days ago (Iím using the super soft anti vibration kit), and Iíve also never lost the GPS lock (I donít think so anyway, since the led was always blue).

2) Whilst doing knife edge drops from upright and gradually increasing the amount the heli was rotated towards being at a knife edge orientation, the final almost completely knife edge drop caused the rescue to kick in again, as it had been, at approximately 9 metres (maybe even 2 to 4 metres lower than 9), but this time it didn't seem to make any attempt to hold position or gain height. It flew off to the right at a slow to steady speed and descent for about 3 seconds before I then hit throttle hold thinking it was going in, but at the last second I managed to flick the rescue switch to manual and level it out, with the blades having almost stopped, so I just managed to get away with it.

3) I was gently rolling from left to right and the rescue activated at about 9 metres, but again it seemed to make no attempt to hold or adjust the position, as it gradually descended and flew into the fence. I tried to stop it happening, but accidentally flicked into normal (idle) mode instead of flicking the rescue switch to the manual position (both switches are on the left), and for the 2 to 3 seconds until the heli hit the fence I was wondering why it wasn't responding. I reckon I probably hit throttle hold (the big switch on the right) at about the instant it hit the fence.

After incident 1) I should have landed and investigated, but I was feeling confident enough that further testing would be okay, since in general the rescue was working most of the time. Even so, at least other users can read about my experience and learn from my mistakes, and hopefully not have it happen to them.

I havenít looked at the logs yet, but Iíll post them on here when I get a chance. The units look completely unmarked, so Iím hoping theyíre still okay.
Gary, the incident you reported could have been avoided if SK had given the control back to you right after the rescue was performed.

I'm always very hesitant to use the SK's hard deck feature because it overrides pilot input until the pilot disables the HD by means of having to manually rock a switch.

I wish the rescue could have a preset duration of 2 seconds maximum for ER just like other rescue systems does.

I understand that in normal operation, the SK rescue is capable of leveling an aircraft from any attitude in less than one second, depending on gain settings, so it makes no sense the system to continue overriding the pilot inputs when the rescue process has been completed after 2 seconds.

Carlos
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Old 04-04-2016, 10:51 AM   #6
GaryDT
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Post SK720 GPS2 - Hard Deck 2 Second Preset Duration

Very good point Carlos.

Yes a 2 second preset would have saved it, since it was about 3 to 4 seconds from the instant the rescue kicked in that the heli hit the fence, and it wasn't really travelling very fast either, but the damage was quite bad. My friend took photos of it before we moved it away from the fence, some friend he is lol

Cheers,

Gary.

Edit: Okay I've just read Xrayted's concerns about the 2 second preset on the other thread. So then perhaps we could have this preset as an adjustable 2 to 4 second option which can also be set to on or off in the setup. The point is though I suppose, the system was failing about 10% of the time, and if it hadn't failed, this potential preset wouldn't have been needed. It's very dangerous for a setup like this to lockout control when it's possible that the position and height control might not work.

Edit 2: I've now read the other points that Xrayted raised (sorry for any confusion caused by these threads interlinking).

1) Yes the system was very carefully set up and tested in 4 different GPS modes during my 1st session with the setup: http://rcheli.club/sessions/view?sessionid=7323

2) We also tested position hold, return to home, and rescue now several times during this 2nd session, and they all worked very well.

3) Yes I should have stopped after the first incident (which I stated before), but what can I say, I was pushing to obtain more inflight behaviour, naughty yes, but that's the chance I took, and I pushed it too far (well not really, I just flicked the wrong switch). Even so, why can the GPS lockout user control when position and height control is not available. Very dangerous.

Last edited by GaryDT; 04-04-2016 at 12:21 PM.. Reason: Edit Added
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Old 04-04-2016, 11:41 AM   #7
jamisonchang
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Default My questions?

I am pleased that others could share their experiences and solutions.... but my original intent in starting the thread was to ask about my GPS after the crash--- the fact that it cannot get a position or barometer reading.


Any thoughts are appreciated
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Old 04-04-2016, 12:41 PM   #8
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=] can you hear anything loose inside the gps, it uses a small memory battery....
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Old 04-04-2016, 12:44 PM   #9
jamisonchang
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thanks as always Georgi. No, I don't hear anything loose though there may be a tiny piece of black plastic in the case. the unit flashes blue (slow) when plugged into the sk 720. does that help at all?
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Old 04-04-2016, 12:45 PM   #10
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Quote:
Originally Posted by jamisonchang View Post
I am pleased that others could share their experiences and solutions.... but my original intent in starting the thread was to ask about my GPS after the crash--- the fact that it cannot get a position or barometer reading.


Any thoughts are appreciated
This may be a dumb question, so please forgive me if so, but are you outside in the open area where you fly when you are trying to get a lock?

Just making sure you are not in the house, on the back porch near the house or other large objects, cars etc, even if outside.

I can sit my heli outside on my building's balcony with a full view of the open sky and will never get a lock. It must be out in the open away from things

You also will not get lock if the system thinks that you need to do the compass swing, but your original post says that the status is showing as OK
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Old 04-04-2016, 12:55 PM   #11
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never a dumb question for someone new like me. am in house but was able to get lock in same place before. tried outside too and same issue.
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Old 04-04-2016, 01:01 PM   #12
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=] are you able to talk to the gps via the software?
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Old 04-04-2016, 01:04 PM   #13
jamisonchang
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yes, it connects and the mode switches with the assigned switches on the tx. it shows compass heading,n
magnetic field strength but will not show lat/long or baro. super bright led used to go solid blue within 20 s now stays green suggesting something awry with gps.thanks
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Old 04-04-2016, 01:28 PM   #14
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=] looks like it's going back to HQ?....
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Old 04-04-2016, 01:30 PM   #15
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that was my suspicion. Does skookum need to give me some sort of return/repair or do I just send it? thanks Georgi
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Old 04-04-2016, 02:53 PM   #16
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that was my suspicion. Does skookum need to give me some sort of return/repair or do I just send it? thanks Georgi
Go to their web site and open a ticket. My old gps 1 had the same issue and it turned out to be a broken antenna issue inside the unit. They soldered it up and it got a lock.
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Old 04-04-2016, 03:02 PM   #17
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Thanks Luvmyhelis.
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Old 04-04-2016, 05:18 PM   #18
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=] as LMH says and clearly mark it as a warranty return to avoid customs delay....
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