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Old 05-25-2012, 01:54 AM   #1
jmanphotos
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Default 3X Photoship one gimbal, Futaba 401's and Spektrum DX6i

Hi Peeps,

I am trying to setup my Photoshipone 3Xpro gimbal and the Futaba 401 gyros for stabilisation. Am having a spot of trouble configuring them with my Spektrum DX6i so that A. they stay in one spot when stationary and B. work properly as a stabiliser.

Currently fine tuning the trim on the tilt axis doesn't get it to stay put 100% .. it will slightly move up or down depending on which way I trim it.
Also when I test the levelling of the gimbal, it doesn't really work very well. Its rather slow and doesnt move too much.

Anyone done these settings before and can help me out ? The spektrum DX6i is a real pain, as it doesn't have many features for the Gyro ... and its got me stumped, cos ive tried a whole bunch of different combinations.

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Old 05-25-2012, 06:38 AM   #2
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Quote:
Originally Posted by jmanphotos View Post
Hi Peeps,

I am trying to setup my Photoshipone 3Xpro gimbal and the Futaba 401 gyros for stabilisation. Am having a spot of trouble configuring them with my Spektrum DX6i so that A. they stay in one spot when stationary and B. work properly as a stabiliser.

Currently fine tuning the trim on the tilt axis doesn't get it to stay put 100% .. it will slightly move up or down depending on which way I trim it.
Also when I test the levelling of the gimbal, it doesn't really work very well. Its rather slow and doesnt move too much.

Anyone done these settings before and can help me out ? The spektrum DX6i is a real pain, as it doesn't have many features for the Gyro ... and its got me stumped, cos ive tried a whole bunch of different combinations.

I've been setting mine up gradually and am yet to install any gyros. I will be operating my system alone for now, and only use a multi-turn servo for adjusting the camera tilt angle so far, without gyro.

So, a question, what servos are you using and are they continuous rotation? I would assume they are.
If so, as they don't have potentiometres in them, there is no reference for where centre is. I have read several times that gyros generally do creep and it is up to the camera operator to manually correct this during flight. Especially the cheaper ones.
Using gyro rate mode is better than hh for this application. The servo should only rotate when there is an input from the rxr/txr. (ignoring the creep). The servo continues to rotate while the radio stick is held away from centre, and the further it is moved from centre the faster the servo rotates. Returning the stick to centre stops the servo, and the servo doesn't auto return to centre.
As you can see, these setups are two person operation.

Hope that helps you get further along.
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Old 05-25-2012, 12:26 PM   #3
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I'm not 100% clear on your issue, but do you have it set up in such a way so that you can control each of the gains on the 401s from the Tx? Also, what do you mean by "staying put"? Does it drift after awhile when actively stabilizing? Because this is the nature of the beast and is difficult to account for in what is essentially an open loop control system (i.e. it doesnt know where it should go back to, it can only compensate for detected angular accelerations) If you want it to stop stabilizing i.e., turn of the stabiliztion temporarily from the control, you can set the gain to around 50% on the dx6i.
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Old 05-27-2012, 06:04 PM   #4
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Crayon box, I am using SAVOX high speed servos that were supplied as an upgrade from PhotoshipOne, also using Futaba 401 gyros, also recommended by PhotoshipOne.
They are continuous rotation servos.

S_linste, my issue is the the servos creep. I try and use the trims to stop that, however it doesn't ever stop 100%. This what I mean by "staying put". The TX is setup for Rate mode, and the sensitivity is set to around 40%. However I can't seem to control each individual Gyro on the spektrum as the Gyros sensitivity wire has to be plugged into the Gyro channel on the RX no ?
I am aware that the gyro don't return to exactly the same position as it stabilized from, however the creeping part and setup of the DX6i is my issue.
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Old 05-28-2012, 07:52 AM   #5
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I thought i read somewhere that the best result is using a seperate gain from individual channels for the gyros.
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Old 05-29-2012, 09:32 AM   #6
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Quote:
Originally Posted by jmanphotos View Post

S_linste, my issue is the the servos creep. I try and use the trims to stop that, however it doesn't ever stop 100%. This what I mean by "staying put". The TX is setup for Rate mode, and the sensitivity is set to around 40%. However I can't seem to control each individual Gyro on the spektrum as the Gyros sensitivity wire has to be plugged into the Gyro channel on the RX no ?
I am aware that the gyro don't return to exactly the same position as it stabilized from, however the creeping part and setup of the DX6i is my issue.
Yes, the creeping is a necessary evil for this relatively primitive arrangement. You basically have to trim out your axis each flight to correspond even to different outdoor temperature. And still, it will creep. I guess the management of these shortcomings needs to be left to your camera operator. I use the dx6i as well and I use the collective channel with a flat pitch curve for on of the gains. Then, I have another pitch curve around 50% flat so i can toggle between normal and stunt to achieve an active gain and a "stay still and do nothing" gain. Then, for the other gyro, I use the gyro switch through the aux channel. The gyro switch allows for two gains. But I only have a two axis gimbal.

Unless you can find two of your three gyros that can run with the same gain (so you can split one of the channels) I think you are going to need a Tx/Rx with an 7th channel.
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Old 05-29-2012, 06:53 PM   #7
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Gyros exhibit bias drift. It's a nature of their design and a limitation that can not be corrected for without accelerometers.

Don't expect solid stabilization with RC helicopter tail gyros. They will stabilize but only marginally well. A better solution is an IMU or AHRS sensor package. The good news is we hope to be testing one within a month.

In the mean time, be sure you have your trim step value on your TX set all the way down to '1'. This will offer finer resolution of trim adjustment.
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Old 05-29-2012, 06:53 PM   #8
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s_linste that was actually my next question ... where does one put the extra two little gain wires if the one gyro port is being taken up by the third gyro. You've answered this.
So, you just use other free channels on the TX and then set a flat pitch curve. When you say flat, do you mean horizontal ?
I have already doubled up two of the gyros to go into the gyro channel .. however not sure if its working properly.
Anyway, i wasn't sure if one could use other channels. So will now try a bunch of different things.
I do find that there is not much leeway between the actual doing something gain and the point where the whole things starts to wig out. I have to keep my gain around 40% before it starts having a fit ... and then anything less than 40% ... it doesn't really do anything.
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Old 05-29-2012, 07:10 PM   #9
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Quote:
I have to keep my gain around 40% before it starts having a fit ... and then anything less than 40% ... it doesn't really do anything.
Hmm.... I suspect you may not have the gyros installed properly. Can you post a few photos?
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Old 06-01-2012, 04:30 AM   #10
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Hi DJ,
Yeh not sure if its setup correctly at all. I will attach some images for you to check out.
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Old 06-01-2012, 04:36 AM   #11
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images of Gyros and control on TX
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Old 06-01-2012, 05:37 PM   #12
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Let's say you want to use the aileron (left right on the right stick of your Dx6i) for the pan axis, the AILE channel out on the Rx takes the male Black-Red-Green wires from the gyro. But the yellow wire grouped with those three needs it's own channel -- GEAR in my case -- for the gain. The Black-Red-Green female from the gyro accepts the servo wire for that axis.
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Old 06-02-2012, 03:01 AM   #13
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setting up the channels for the control of the head is no problem. I have pan, tilt and roll all in their prospective channels on both sticks. However its the gain wires that Im confused as to where they go. You are saying gear channel, however I am running the TX in helicopter mode, as to get the Gyro control option. Does the gear replace the gyro channel if in Aeroplane mode ?
It would be great if someone could post some diagrams or pics of their setup of where they exactly have their 3 gyro gain wires and where on the TX they control them from .
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Old 06-02-2012, 03:44 PM   #14
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My Dx6i is set up in heli mode as well. I just read what was on the Rx (i.e. gear) but i really mean gyro. I had to disassemble part of my 2-axis so it wouldn't make useful pics. But the channel you use to control your gain can be any one. The gyro doesn't know or care which channel you use as all the channels have the same output. It's back on the Tx where you can have a good or bad channel choice. Channels with two banks intended for dual gyro rates are ideal. Pitch or throttle channels are useful as they can be set as flat curves and effectively behave exactly like the gyro channel. This, of course, presumes those channels are not busy controlling other things.
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Old 06-02-2012, 05:47 PM   #15
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I looked at the pics and it seems you do have them installed properly (one axis removed).

Quote:
I am running the TX in helicopter mode, as to get the Gyro control option.
it does not matter if you are in heli mode or not. The gyro will work with any channel even in airplane mode. There is nothing different about the 'gyro' channel in heli mode or any other channel except for the 'name' of the channel. The output is the same for all channels, 900us - 2100us pulse width.

Are you positive the 401 is in rate (normal) mode and not AVCS?
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Old 06-02-2012, 08:08 PM   #16
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Im pretty sure the gyro's are in Rate mode.... as when I increase the gain above 50% they switch over and start wigging out (shaking around).
They do work in terms of trying to stabilise the gimbal, however they don't seem to actually compensate very much. So for example, when I tilt the chopper to the left or right, the gimbal does compensate a little bit, but not very much.
To sum up, I think i may have it all setup correctly, however my concern is that they don't compensate enough. I will try and take a video so that you can see exactly how much they do compensate and then let me know if this is normal or not.
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Old 06-03-2012, 10:04 AM   #17
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I can tell you that in my case, adjusting the gain closer to zero (on the Tx) will cause the gyro to compensate increasingly so until begins to overcompensate (move farther in the compensation direction than necessary relative to the disturbance direction)
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Old 06-03-2012, 02:50 PM   #18
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The gyro's gain channel is simply monitoring the signal wire from your Rx just like a servo, in both cases the device is simply looking for the pulse width of the signal wire on any given channel you choose (roughly a 1 to 2ms range in pulse width, where 1.5ms is servo center or 0% gain on gyro. Read more here: http://en.wikipedia.org/wiki/Servo_control).

The confusing part about programing some gyros in rate mode actually has more to do with how your radio's programming is setup for gyro gains.

When your radio gives you available values of 0-100, it's important to understand the basic concept that this represents the full 1 to 2ms range of pulse width, with 50 being 1.5ms, or 0% gyro gain. That means as you decrease the value from 50 to 0, you are increasing the gyros gain value in Rate mode from 0 to 100%. As you increase the radio's value from 50 to 100, you are increasing the gyros gain in HH mode from 0 to 100% (useless for gimbal gyros).



Understanding this will make setting up gimbal gains on various channels much easier, but the advantage to fully understanding this stuff is not only limited to setting up gyros. Most IMU's, FBL stabilization, and other types of controllers use radio endpoint type programming to set modes and gain values.
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Old 06-04-2012, 06:21 AM   #19
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So I went back to the drawing board and tried a whole lot of different configurations. I tried plugging the second Gyro into the throttle channel and set a straight line at 50% ... it didn't really work that well.
The tilt axis plugged into the gear channel and set to around 45% it worked better than the other axis, however not really that much. Then I tried putting bot axis into the one gear channel via a Y lead, and this didn't work as well either.
I have attached a video .. however just realised that maybe it would have been better to put my camera on the gimbal. Lol.

Can anyone get an idea of how little it moves ? Is that normal .... ??


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Old 06-04-2012, 11:16 AM   #20
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The camera tray should move the same amount you deviate the helicopter. If it does not you have too little gain. Increase your gain.

If you still are having troubles we'd be happy to look at it if you want to send it to us. I just configured a 3X Pro with a gyro last night to confirm operation and it works great.
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