crash1sttime said:
Not sure it's that simple, mine and most other Vision Plus users don't have a problem, but it is important to have it near perfectly level when you calibrate.
Might be the plus has a somehow more sensitive ...thingy.
Phantom is not stable after IMU calibration.
- Thread starter Cytranic
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Not sure it's that simple, mine and most other Vision Plus users don't have a problem, but it is important to have it near perfectly level when you calibrate.
Might be the plus has a somehow more sensitive ...thingy.
ELHEAPO said:
I've been doing advanced calibrations. Done 5 so far today with different paper shims. Getting closer.
Cytranic said:
Thanks for figuring this out!
I've got it working much better now. I think I did 21 total flights and calibrations. I would't say its perfect, but it stays within a 2 foot circle when yawing now and I don't think it was any better than that new. I've flown some low slow stuff around my yard and its much easier to control.
Pieces of paper:
FL: 18 FR: 4
RL: 12 RR: 0
Glad I could help! 2 foot of drift is very acceptable imo. I went from a 20 foot drift to about 2. I'm happy.
Cytranic said:
Cory: is it recommended to do a compass calibration after each advanced IMU calibration?
ELHEAPO said:
I used normal sheets of paper cut up into business card sized squares and then placed under each foot. It took me most of the morning just because of wait time to let IMU cool down after each flight. Worth the hassle though, it flys great now.
Wish I hadn't messed with IMU calibration in the first place. I really didn't have a reason to other than running through everything so I was familiar with the new toy and all its quirks. Now I know at least.
Let me think this through...
So the yaw drifts relate to the IMU..
When I do an IMU calibration, I only look at the roll (left right) and make sure its level by using a spirit/bubble level. When you guys use paper/cards to adjust heights, then I assume that the pitch (fwd backward) needs to be level also.
So assuming that the NAZA/IMU is installed perfectly on the main board then technically what we need to do is find a table that is perfectly levelled at all axis.
So the yaw drifts relate to the IMU..
When I do an IMU calibration, I only look at the roll (left right) and make sure its level by using a spirit/bubble level. When you guys use paper/cards to adjust heights, then I assume that the pitch (fwd backward) needs to be level also.
So assuming that the NAZA/IMU is installed perfectly on the main board then technically what we need to do is find a table that is perfectly levelled at all axis.
Mako that's the idea. But it seems like some of the IMUs aren't level in the body so have to shim it up to get the IMU level to run the calibration.
I am in the process of correcting mine. I've made about 8 to 10 advanced IMU calibrations adjusting the cards under the skids.
OBSERVATION: when in a hover and the back of the quad is pointing to my face, if I move the left stick left (causing it to yaw counter-clockwise) it drifts around to the left and back, sort of in a circle. When I push the stick to the right (causing it to yaw clockwise) it does the opposite, drifting to the right and circling right and back.
So, it definitely wants to drift to the rear a little and to right or left, depending which direction I'm yawing it.
CORRECTIONS SO FAR: I've been setting the quad on the table (where I did an initial Adv IMU Cali with no correction) and since been adding cards to the front left and right skids equally.
I got it to tighten up the turn, meaning that it drifts to the side and back in about a 3' circle, which coming from what was about a 6' circle. Always to the side I'm pushing the stick and to the rear, never front.
So, for fun I decided to go from about 10 cards under each left/right skid to 25 cards to see if if would cause it to yaw level or forward. All that did was stretch the side and rear yaw drift dramatically, about 10' circle.
After that I put it back on the table and did another adv IMU cali with no cards and tested. Back to a tighter, 2' side/rear circle yaw.
QUESTION: how come when I lifted the front of it much further (going from 10 cards to 25 cards under front skids) it didn't make it want to yaw level or push the yaw drift to circle forward? I thought you lift the side of the quad opposite of the direction its drifting?
Continuing the corrections and testing, but would like your input from those who are getting favorable results from their corrections.
OBSERVATION: when in a hover and the back of the quad is pointing to my face, if I move the left stick left (causing it to yaw counter-clockwise) it drifts around to the left and back, sort of in a circle. When I push the stick to the right (causing it to yaw clockwise) it does the opposite, drifting to the right and circling right and back.
So, it definitely wants to drift to the rear a little and to right or left, depending which direction I'm yawing it.
CORRECTIONS SO FAR: I've been setting the quad on the table (where I did an initial Adv IMU Cali with no correction) and since been adding cards to the front left and right skids equally.
I got it to tighten up the turn, meaning that it drifts to the side and back in about a 3' circle, which coming from what was about a 6' circle. Always to the side I'm pushing the stick and to the rear, never front.
So, for fun I decided to go from about 10 cards under each left/right skid to 25 cards to see if if would cause it to yaw level or forward. All that did was stretch the side and rear yaw drift dramatically, about 10' circle.
After that I put it back on the table and did another adv IMU cali with no cards and tested. Back to a tighter, 2' side/rear circle yaw.
QUESTION: how come when I lifted the front of it much further (going from 10 cards to 25 cards under front skids) it didn't make it want to yaw level or push the yaw drift to circle forward? I thought you lift the side of the quad opposite of the direction its drifting?
Continuing the corrections and testing, but would like your input from those who are getting favorable results from their corrections.
This has been an interesting post and decided to try my hand at the calibration process suggested. However, I came up with a simple tool to help me with the process that others may be interested in copying. A small piece of plywood with T-nuts in each corner; four 2 inch bolts are threaded into the T-nuts from the bottom; on the top there is a washer and a wing nut on each bolt end. I then put the platform on a somewhat level surface and threaded each of the corners in or out until I achieved a level surface front to back and side to side. I then tightened down the wing nuts which keeps the platform level. I then placed the Phantom on the platform and did my calibration. Weather prevents me from testing out the accuracy of the calibration but the intent is to then readjust the platform by raising or lowering the appropriate corners. I believe this achieves a more accurate way of adjusting the stance of the Phantom over the use of folded paper or business cards. Once a final calibration is achieved, I will lock my setting in. For future calibrations, I just need to place the platform on the same table that I did the initial setup and place the Phantom back in the same position. Also, its hard to see, but the head of each bolt has a mark on it that I will use to determine the number of turns I make as I adjust the platform. So if I find I over compensated, I can back off the appropriate number of turns. I attached some photos if anyone is interested.
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Mopar Bob said:This has been an interesting post and decided to try my hand at the calibration process suggested. However, I came up with a simple tool to help me with the process that others may be interested in copying. A small piece of plywood with T-nuts in each corner; four 2 inch bolts are threaded into the T-nuts from the bottom; on the top there is a washer and a wing nut on each bolt end. I then put the platform on a somewhat level surface and threaded each of the corners in or out until I achieved a level surface front to back and side to side. I then tightened down the wing nuts which keeps the platform level. I then placed the Phantom on the platform and did my calibration. Weather prevents me from testing out the accuracy of the calibration but the intent is to then readjust the platform by raising or lowering the appropriate corners. I believe this achieves a more accurate way of adjusting the stance of the Phantom over the use of folded paper or business cards. Once a final calibration is achieved, I will lock my setting in. For future calibrations, I just need to place the platform on the same table that I did the initial setup and place the Phantom back in the same position. Also, its hard to see, but the head of each bolt has a mark on it that I will use to determine the number of turns I make as I adjust the platform. So if I find I over compensated, I can back off the appropriate number of turns. I attached some photos if anyone is interested.
That's fkn ingenious!!! Gonna make one today!
Can you do me a fav. Can you use a bubble level and tell me in both axis whether it was dead centre when you found the phantom yaw's g-spot?
thanks
I will when I do. Right now its 5 degrees F in Connecticut so my testing and further calibration is on hold. Its suppose to warm up in the next few days and I am hoping to get back out there.
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Definitely an ingenious balancing board setup, Mopar Bob.
I've been following this thread as I too have discovered some instability when turning the quad on its axis.
I have two P2V+ models, one had not had any significant mods done to it, by that I mean I've basically placed a CF camera guard and inertia guard on it.
The other bird however has recently acquired a pair of Wi-Fi antenna's as well as a tracker transceiver (46 grams ) in addition to both camera guards.
Both quads have had advanced calibrations done to them within the last 9 months of ownership, however I have found that only the bird which has had additional weight added to the model is being affected.
I had wondered if some of these issues mentioned in the OP as it relates to being unstable in flight particularly after an IMU calibration were in some way related to the distribution of added weight to a model. This may make it a bit more difficult for the control module to react to various maneuvers, and maintain a level attitude, causing some drifting or unsteady behavior as it steady's itself within the GPS parimeters. This is not to say that obtaining max stationary level positioning prior to calibration is not important, and I wouldn't be surprised if I'm way be way off base here. It was just a thought!
Oh! btw, my quad appears to hover, and fly level, as best as I can determine by eye balling it in flight.
It may be good to get some comparison stats going, as to how many are experiencing the issue with a modified quad carrying additional equipment, as opposed to a stock out of the box unit, or one with minimal payload added.
I've been following this thread as I too have discovered some instability when turning the quad on its axis.
I have two P2V+ models, one had not had any significant mods done to it, by that I mean I've basically placed a CF camera guard and inertia guard on it.
The other bird however has recently acquired a pair of Wi-Fi antenna's as well as a tracker transceiver (46 grams ) in addition to both camera guards.
Both quads have had advanced calibrations done to them within the last 9 months of ownership, however I have found that only the bird which has had additional weight added to the model is being affected.
I had wondered if some of these issues mentioned in the OP as it relates to being unstable in flight particularly after an IMU calibration were in some way related to the distribution of added weight to a model. This may make it a bit more difficult for the control module to react to various maneuvers, and maintain a level attitude, causing some drifting or unsteady behavior as it steady's itself within the GPS parimeters. This is not to say that obtaining max stationary level positioning prior to calibration is not important, and I wouldn't be surprised if I'm way be way off base here. It was just a thought!
Oh! btw, my quad appears to hover, and fly level, as best as I can determine by eye balling it in flight.
It may be good to get some comparison stats going, as to how many are experiencing the issue with a modified quad carrying additional equipment, as opposed to a stock out of the box unit, or one with minimal payload added.
That is awesome Bob! I'm going to have to build one of those. My Vision+ is stock and I had the drifting issues after running the first IMU calibration.
So, after all the back and forth trying to get the paper pieces just right under my Plus V3's skids to fix the yaw drift, which I probably did about 8 to 10 calibrations, I decided to be smart and do a cali on a level surface first!
My Plus is only a month old and last week or so I noticed it drifted about 3 feet or more to the rear and left when I yawed. So, I immediately started raising the skids on the opposite side and trying to counter the drift, assuming my IMU wasn't level inside the quad.
Today, I got my bubble level and discovered that my kitchen granite counter tops are dead on level, so I just did a calibration there, flew it and now it is dead on when it yaws. It's like it is mounted on the end of a pose when it yaws! It's fantastic!
If only I'd thought to do a calibration on a level surface FIRST ;-)
My Plus is only a month old and last week or so I noticed it drifted about 3 feet or more to the rear and left when I yawed. So, I immediately started raising the skids on the opposite side and trying to counter the drift, assuming my IMU wasn't level inside the quad.
Today, I got my bubble level and discovered that my kitchen granite counter tops are dead on level, so I just did a calibration there, flew it and now it is dead on when it yaws. It's like it is mounted on the end of a pose when it yaws! It's fantastic!
If only I'd thought to do a calibration on a level surface FIRST ;-)
Pmcdn said:
Congrats but why wouldnt you do it on a level surface in the first place? That is one of the criteria of an IMU calibration.
I've been wondering... Would the drift be noticed with GPS turned off, in ATTI mode? While flying indoors or outdoors when there really is no wind?
Also I don't think it is important how the NAZA main controller is installed inside. With the IMU calibration you are basically telling it to take the current level as zero. I would be more suspicious if the phantom shell is made perfectly level. Or more specifically that motor mounts are perfectly parallel to the legs. I guess NAZA expects that when you calibrate that your motors are perfectly level to the ground.
Maybe with propellers off it could be posible to put a small bubble level on each motor, one by one, and check the level there.
Also I don't think it is important how the NAZA main controller is installed inside. With the IMU calibration you are basically telling it to take the current level as zero. I would be more suspicious if the phantom shell is made perfectly level. Or more specifically that motor mounts are perfectly parallel to the legs. I guess NAZA expects that when you calibrate that your motors are perfectly level to the ground.
Maybe with propellers off it could be posible to put a small bubble level on each motor, one by one, and check the level there.
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