Calibration & Tuning

A project log for Handheld Camera Gimbal

For Mirrorless and Mid-Size DSLRs.

matt-barrMatt Barr 07/23/2017 at 00:540 Comments

Before calibration, the gimbal should be reasonably well balanced so the motors don’t have to work as hard. I used 1 Oz fishing sinkers for counterweights. To calibrate, I used a simple photography light stand to brace the gimbal for tuning. Having the assembly well balanced is absolutely necessary for the initial accelerometer and gyro calibration.

Calibration and tuning requires adjusting the power and PID settings. A good rule of thumb is to set the power as high as possible without overheating the motor. Power, in gimbal terminology, is essentially the torque applied to the motor. More power makes it harder to move when bumped, which is a good thing, but too much will cause the motor to overheat.

The PID settings more or less control the motor’s behavior.  PID is shorthand for Proportional, Integral, and Derivative control.  A good way to calibrate the PIDs is to set them all to zero, and work on them one motor at a time.  I found that it’s best to start with the pitch motor, then roll, and finally yaw.  The SimpleBGC software has an auto mode that is useless.  Don’t use it.  Instead, tune the PIDs manually.  Start with (D) and add until it starts to whine, then back off until it stops.  Then, add (P) until the motor has enough torque.  If it overshoots, back off a little.  It should return to level smoothly.  Finally, add (I) to adjust drop time on each axis.  Too much (I) will cause vibrations.  A well-tuned gimbal will be responsive, but should stay stable with small bumps.  The result is smooth footage.

My Initial PID Settings:
Roll: P-40, I-0.1, D-120
Pitch: P-20, I-0.1. D-30
Yaw: P-35, I-0.1, D-100

Final PID Settings:
Roll: P-18, I-0.57, D-78
Pitch: P-24, I-0.49. D-13
Yaw: P-22, I-0.20, D-56