SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Nov 19, 2012, 12:44 PM
Product Manager at Hobbico
GWRIGHT's Avatar
United States
Joined May 2000
5,163 Posts
Interesting. I guess Colin Mill was wrong back in the early to mid 90's when he introduced us to the CSM540 and called it the first "heading hold" gyro, explaining how he had introduced the integral component in the PID loop as an adjustable parameter .

I'll butt out now.
GWRIGHT is offline Find More Posts by GWRIGHT
Reply With Quote
Sign up now
to remove ads between posts
Old Nov 19, 2012, 02:27 PM
CP heli ≠ 3D heli
Gedexas's Avatar
United States, NJ, Point Pleasant Beach
Joined Mar 2009
1,676 Posts
Quote:
Originally Posted by GWRIGHT View Post
Interesting. I guess Colin Mill was wrong back in the early to mid 90's when he introduced us to the CSM540 and called it the first "heading hold" gyro, explaining how he had introduced the integral component in the PID loop as an adjustable parameter .

I'll butt out now.
He was not wrong. The PID loop can coexist with a heading hold gyro and with a rate mode gyro. The PID loop is not responsible for holding a steady course, it is responsible for managing other factors inherent in gyroscopic stabilization (among many other uses), mainly to prevent overshooting.

Example of where a PID loop is used would be to control a hot/cold water faucet to maintain specific temperature. If there is a delay between opening hot water valve and the actual hot water coming out of the faucet (common thing in a shower), then simply having a thermostat opening the valve and wait for the hot water to arrive would result in burned skin. This is where a PID loop is used. It is not the PID loop that sets the temperature, it is the job of a thermostat. The PID loop would be responsible in preventing the water from getting too hot or too cold.

Same thing with a gyro, except a rate mode gyro equivalent of a thermostat does not try to maintain a specific water temperature, but only tries to prevent the temperature from changing too quickly (controls the rate of change).
Gedexas is offline Find More Posts by Gedexas
Reply With Quote
Old Nov 19, 2012, 03:11 PM
Product Manager at Hobbico
GWRIGHT's Avatar
United States
Joined May 2000
5,163 Posts
hmmmmmmm

"The contribution from the integral term is proportional to both the magnitude of the error and the duration of the error. The integral in a PID controller is the sum of the instantaneous error over time and gives the accumulated offset that should have been corrected previously. The accumulated error is then multiplied by the integral gain () and added to the controller output."
GWRIGHT is offline Find More Posts by GWRIGHT
Reply With Quote
Old Nov 19, 2012, 03:35 PM
CP heli ≠ 3D heli
Gedexas's Avatar
United States, NJ, Point Pleasant Beach
Joined Mar 2009
1,676 Posts
Quote:
Originally Posted by GWRIGHT View Post
hmmmmmmm

"The contribution from the integral term is proportional to both the magnitude of the error and the duration of the error. The integral in a PID controller is the sum of the instantaneous error over time and gives the accumulated offset that should have been corrected previously. The accumulated error is then multiplied by the integral gain () and added to the controller output."
And how does this apply to my problem?

See the black dotted line line?

Well, in my gyro (cx3x1000) that black dotted line is not straight over time (rate mode), the PID loop (red line) can chase that black dotted line all day long, but in the end, both of those lines will not be straight because my gyro operates in rate mode.
Gedexas is offline Find More Posts by Gedexas
Reply With Quote
Old Dec 03, 2012, 11:22 PM
CP heli ≠ 3D heli
Gedexas's Avatar
United States, NJ, Point Pleasant Beach
Joined Mar 2009
1,676 Posts
Ok, I received my Robird g31 today and I'm seeing somewhat similar behavior to the cx3x1000, that is, the swashplate slowly returns to center when sitting on the bench.

I have a question to BeastX owners. Does the BeastX let the swashplate stay tilted after an input from the transmitter? Like the mCPx?

I haven't flown the g31 yet, but from all the indications, this will perform the same way the cx3x1000 did, maybe worse, because I can't adjust anything meaningful in the setup software, not even PID settings.

I'll let you know if I like it after I have flown it.
Gedexas is offline Find More Posts by Gedexas
Reply With Quote
Old Dec 04, 2012, 12:00 AM
CP heli ≠ 3D heli
Gedexas's Avatar
United States, NJ, Point Pleasant Beach
Joined Mar 2009
1,676 Posts
I tried to hover the G31, with training gear, and good thing I had it on. I think this is the worst FBL unit ever and I recommend the $30 cx3x1000 over this thing, at least that one can be made to fly at all.
Gedexas is offline Find More Posts by Gedexas
Reply With Quote
Old Dec 04, 2012, 05:45 PM
CP heli ≠ 3D heli
Gedexas's Avatar
United States, NJ, Point Pleasant Beach
Joined Mar 2009
1,676 Posts
Got the G31 to fly by shortening the servo horns, still not digging it, can't get 12 degrees of collective with short servo horns.
Gedexas is offline Find More Posts by Gedexas
Reply With Quote
Old Dec 26, 2012, 04:51 AM
Suspended Account
Joined Oct 2012
151 Posts
cx3000 is probably,until now the cheapest one in the market and works also cheaply.
bigaoleamy is offline Find More Posts by bigaoleamy
Reply With Quote  (Disabled)
Old Dec 26, 2012, 06:14 PM
Registered User
Sunnyvale, CA, USA
Joined Apr 2000
1,847 Posts
For what it is worth, hiller dacay rate approximates to adjusting the flybar weight. (Slower = heavier) Think of how fast the flybar returns to its neutral plane of rotation after an input. It is not the value of the I term in PID (unless the designer was on something). It tells you how fast the value off the I term will "washout" with time.

There is no equivalent on the tail since most modelers want "heading hold" on the tail.

The hiller decay (more properly termed the washout rate) adjustment makes a lot of difference to how the heli "feels" and should be adjustable. Not all designers understand this and fix it. If their choice suits your style OK, if not.......

Small print: Since the various designers like to add "features" that may or may not have benefit - to improve sales, they tend to hide behind non engineering terms like "agility", "flybar emulation" and other BS so your mileage may vary

Signed: Cynical retired aerospace engineer.
teamdavey is online now Find More Posts by teamdavey
Last edited by teamdavey; Dec 26, 2012 at 06:40 PM. Reason: Clarification and added value
Reply With Quote
Old Jan 03, 2013, 04:17 AM
Suspended Account
Joined Oct 2012
151 Posts
another new FBL unit is being designed now

http://www.bglmodel.com/news_read.asp?id=157
bigaoleamy is offline Find More Posts by bigaoleamy
Reply With Quote  (Disabled)
Old Jan 03, 2013, 09:57 AM
CP heli ≠ 3D heli
Gedexas's Avatar
United States, NJ, Point Pleasant Beach
Joined Mar 2009
1,676 Posts
Quote:
Originally Posted by bigaoleamy View Post
another new FBL unit is being designed now

http://www.bglmodel.com/news_read.asp?id=157
Just a wild shot in the dark: If the software is not finished yet, and if you can influence it's development, please try to implement a setting similar to "trim lock" in the CY Total-G FBL, otherwise you new FBL controller will be just another average FBL controller.
Gedexas is offline Find More Posts by Gedexas
Reply With Quote
Old Jan 03, 2013, 07:30 PM
Suspended Account
Joined Oct 2012
151 Posts
Hello Gedexas which one do you think is the best in the market for the moment? CX3000?
bigaoleamy is offline Find More Posts by bigaoleamy
Reply With Quote  (Disabled)
Old Jan 03, 2013, 10:26 PM
CP heli ≠ 3D heli
Gedexas's Avatar
United States, NJ, Point Pleasant Beach
Joined Mar 2009
1,676 Posts
Quote:
Originally Posted by bigaoleamy View Post
Hello Gedexas which one do you think is the best in the market for the moment? CX3000?
Anything I write is, of course, only my opinion. My experience with flybarless systems and programming in general is very limited, but if you ask, here it is.

The CopterX is not the best, but the price tag is so attractive, that it really does not matter if it's not the best. The best units cost a lot, like ten times the cost of the CopterX unit. People call it diminishing returns.

That being said, I believe that the cheap FBL controller *can* perform as good as the expensive units, provided that the software is flexible enough. So, for example, if the CopterX unit allows me to change one more variable, it will blow any high dollar unit out of the water. That's all it takes, just one more variable, but for some reason the designers of that controller locked that away.

Of course, all of my "problems" are not really a big deal, my idea of perfection is different form the rest of the normal people. Therefore, technically, it's not the FBL unit that has the problem, it's me.
Gedexas is offline Find More Posts by Gedexas
Reply With Quote
Old Jan 04, 2013, 04:04 AM
Suspended Account
Joined Oct 2012
151 Posts
Personally also tried CX2000,for the price,I thought it's ok,afterall,it's just 30 dollars.but for 3D flight,not a good bargain.You can try bgl new FBL unit,the performance is same as BeastX on Electric heli and even super on nitro heli.
bigaoleamy is offline Find More Posts by bigaoleamy
Reply With Quote  (Disabled)
Old Jan 11, 2013, 09:17 AM
Registered User
China, Jiangsu, Wuxi
Joined Apr 2012
55 Posts
Quote:
Originally Posted by bigaoleamy View Post
Personally also tried CX2000,for the price,I thought it's ok,afterall,it's just 30 dollars.but for 3D flight,not a good bargain.You can try bgl new FBL unit,the performance is same as BeastX on Electric heli and even super on nitro heli.
We will carry all new BGL gyros on our sale web. Hot sale FBL 007.
Superior Hobby is offline Find More Posts by Superior Hobby
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Help! Flybar or flybarless? Which one do your prefer? super2012 Electric Heli Talk 55 Aug 07, 2012 11:41 PM
Question cheap flybarless system Hellysmack Mini Helis 1 Jun 23, 2012 03:37 PM
Discussion Long Range System, Which one?! MtnSnowFlyer FPV Talk 2 Jun 16, 2012 06:13 AM
Question Which Flybarless System Greg_E Electric Heli Talk 8 Feb 12, 2011 06:17 AM
Discussion Cheap, good quality nitro's. Any good sites? Faithflyer Fuel Warbirds 1 Jan 30, 2008 10:57 PM