As more people begin taking the challenge of building their own 3 Axis Gimbal Stabilizer, there have been numerous questions with still little information. One popular question relates to calibrating the IMU sensor. In this video I attempt to show my method of performing the 6 Point Calibration of the IMU sensor and why I choose to do it this way.
Unlike using a cardboard box, this method using a Leveling Cube ensures you can visibly see how level you are before performing calibration. It also allows the sensor to remain completely flat across the cube.
If you look closely, you can see that laying the sensor down over the exposed solder pins may cause inaccurate results. Perform your calibration with the sensor level using only the flat area. Hopefully this bit of information has been helpful and may allow you to get slightly more accurate results from your 6 Point IMU Calibration.
At first I thought these cubes were merely a novelty item, but after working with these gimbals, I have found so many more uses for them. They are great for checking how level your gimbal is when placed on a stand while balancing your camera. They are also great for checking the level of your camera immediately after powering up your gimbal (make sure your horizon is level before shooting). Great little item to have around for just under $2.50 + Free Shipping, I suggest grabbing the cubes with 3 bubble levels built in (click here)
Hot Shoe Cube 3 Axis Bubble Level
tom
@matt The method for calibrating the IMU here I find a bit flawed.. in the GUI when doing the 6 point calibration, you can see any movement on a bar with green orange and red. The slightest movement affects the gyro, so by physically holding the imu level with your hands while calibrating is going to cause errors. When I calibrate the IMUs (cam and frame imu) I simply leave it on the gimbal and balance it on a blanket in all the orientations.I have found it more important to keep the IMUs COMPLETELY still (again, you can see the movement on that bar), and just using your eye to orientate the 6 points. The first point must always be Z+(whatever orientation the IMU is in when the camera and gimbal are level) so if you have the imu mounted sideways, you will start calibration with it that way. Also check that the yaw motor is not reversed, you can do an auto detect under motor configuration in the gui, but double check the motor poles as the gui never detects that correctly for some reason. Hope this helps
Matt
@Lee hey Lee, just wondering if you ended up having any luck figuring out your issue there? I've been having the exact same slipping issue, bit on all axis. Haven't been able to find out how to fix yet.
Emm
Post author@Sara - Here's some additional information. https://gimbal.cheesycam.com/downloading-installing-and-launching-simplebgc-software-mac-osx/
Sara
Is that a calibration software, if so whats its name and how to I get it?
Emm
Post author@Lee - You may want to try to recalibrate the frame IMU, but that would require you to remove it from the frame. Also just make sure you don't have any wires that could cause interference to the sensor. They can be sensitive to magnetic interference from other cables.
Lee
I'll play with the camera balance to see if that will help compensate, but it seems more fundamental than that. For example, even sitting perfectly still, no motors on, the yaw error shown in the monitoring tab just climbs steadily all the time, then drops and starts climbing again. Every other sensor is just solid as can be. Makes me wonder if I have a faulty frame IMU.
Lee
In any mode that operates the yaw motor I get that drift. Disabling the frame IMU sensor seems to get rid of it, but also gets rid of some of the stability. And when I'm in SimpleBGC (2.42.b6) the yaw error indicator just swings like mad. In my follow tab I only have one profile that enables "follow YAW", with a 0 offset and 15 speed.
Emm
Post author@Lee - This could be a few things.
First try to hit 'Calibrate Gyro' in the software. So while doing this have someone hold the frame and camera perfectly squared up. Then hit calibrate gyro and wait until it beeps several times and stops beeping.
It could also be the balance of your camera. If it's not perfectly balanced and naturally swings to one side, it will think you're performing a follow pan and wants to follow with you.
When follow mode is enabled, you set the amount degrees before it responds. Try cycling through the different profiles (push the joystick in) and let me know if it still drifts when your in Profile 1, Profile 2, Profile 3, etc. If it doesn't drift in one profile, then it could be a joystick setting.
Lee
Thanks for that insight. I've now calibrated both of my IMU's carefully, and yet I'm getting massive yaw errors that translate into a constant counterclockwise drift; the yaw will drift about 90 degrees in about 20 seconds if I'm not constantly correcting it on the fly. What the heck and I missing? I've searched forums for yaw drift correction and found nothing...
Emm
Post author@Lee - As far as I know, it should always be Z up first.
Lee
Maybe this is a dumb question, but haven't seen it answered anywhere. I've got my camera IMU working great, but my yaw IMU has lots of error. When calibrating that one, should I calibrate UP first (which on mine would be -Y), or Z, which is the IMU laying flat like on my camera IMU and like in your demo? I'm assuming UP, but maybe that's why I've got so much error...
Emm
Post author@Will - You calibrate both. You have to first select which sensor in the software, then go through the calibration. Then select the other sensor and do the same.
Will
Hi Emm,
The 32 bit version of the Came 7000 has 2 sensors on the same wire. Do you calibrate both or just the one on the end of the wire that sits above the camera?
William
IAP
Hi Emm,
I found the USB port on the unit board.
William
IAP
Hi Emm,
How do you plug the unit into the USB port of my computer?
I don't see a USB cable/connector as part of my kit. I see where the pins are on unit, but I have now way to connect them with my computer. Is this something extra I have to order or will a electronics store have one?
William
Emm
Post author@Akos - Not for the sensor calibration. You'll hear several beeps meaning the settings have been confirmed. If you change other PID settings you always need to hit write. I know this works because you'll get a red lettering message saying the IMU is not calibrated. After going through these steps without hitting write, you'll see the message go away. But if you think you need to hit write, I don't think it will do any harm.
Akos
No need for the write button?
Jason Ko
It's so hard to work with these setups... Would you be able to set PID settings? I've downloaded yours,but does not work with my setup (5d2 with tamron 24-70)
I do have came 7000 but I have one up for sale... If anyone interested, please contact me via [email protected]
Robert Shaver
Nice tip for caliberation.
It seems like that sensor board should be installed parallel to the flat bottom of an enclosure. If something shorts two of those bare leads together it could go up in a puff of smoke or the controller could be damaged also. A power to ground short can burn traces right off the circuit board. I know ... I've done it.