BaseCam Pro and Motor drive gear reduction accuracy?
  • Hi Everyone,

    I am looking for some advice from anyone who has used the new Pro controller with magnetic encoders setup with a gear reduction? I am wondering if the new controller and magnetic encoders make using drive gears with a 3:1 or 5:1 reduction better than running the 32 bit controller alone. I setup a gimbal a couple years ago before encoders were available. The gimbal would stabilise but the motors could not spin up fast enough to keep the camera locked on target during quick movements. If the gimbal was moved slowly the stabilisation effect was not to bad but no where near as accurate as a gimbal with direct drive motors.

    Some background on my build. I am designing a gimbal capable of stabilising the BlackMagic URSA Mini to be used handheld out the door of a helicopter. Looking to achieve good stabilisation at speeds up to 100kph or faster. I plan on selecting some of the largest encoded motors on the market or even custom building even larger motors up to 150mm diameter with 3:1 or 5:1 reduction.

    My questions:

    1. Are some of the large motors with encoders capable of spinning up to a faster RPM?
    2. Has anyone built a high torque gear reduction gimbal with encoded motors? Is there any test videos?
    3. Will encoders provide the accuracy required for a gear reduction gimbal?

    Any info or help would be greatly appreciated.

  • It is important that the gear system is low friction and no free play. You should use Pro Board and low resistance motor, I think running it 24V and around 3 to 5 ohm motor max 24 poles would be good, that will spin fast.

    However, big diameter motor has high inertia and it takes time to spin it to the required speed.

    A well made 150 mm 5 ohm motor (as many turns that you can fit to the stators 3 to 5 ohms) at 24 v is pretty strong alone. On such system I would test pitch and roll without gear. it is more important to minimize the size and think about aerodynamical forces and aerodynamic balancing.
  • Thanks for your thoughts Garug. I do agree with you using direct drive on roll and tilt. I feel I could probably get away with direct drive if using the 110mm motors. Maybe even use dual motors on the tilt axis. Its the yaw axis I require all the torque. I have come across some 150mm custom made motors that look to be verified around 97 N of torque. I think this would be strong enough direct drive.

    Has anyone verified the Nm torque of the Ipower 110 motor? I have seen some Chinese sites saying its around 13kg but really that means nothing.

    Also because my gimbal application will be used in high turbulent wind applications I am afraid no matter the torque I'm still going to get small jitters or vibrations from the wind. This is why I plan on building a very compact 2nd gimbal frame inside an aerodynamic capsule. This 2nd gimbal will stabilise an extra 15 degrees movement to deal with the wind destabilising the main gimbal frame.

    Any thoughts on this dual gimbal setup. I know there is not a controller made for this yet but I am in the process of design currently.
  • Only the inner gimbal will need stabilization. The outer gimbal is just pan/tilt control and can work with powerful reduction gear motors, but better have them good quality also to avoid any sudden movements.

    But I tought you said handheld?
  • Will, I am using the GBM110 motor + encoder in a similar situation (Extended board, not Pro board). Currently, with a Canon C100 and Sigma 18-35 I am only able to achieve about 55mph on an automotive application. Where did you find the custom motors? In order to pass more current through the GBM110, you need to rewind the motor to lower resistance (3 to 5 ohms like Garug said). I will be doing this soon and using the Pro Board to supply ~8a to the motor vs. the 1.3a limited by the 17.8ohm resistance and 24v.

    Again, where did you find the custom motors?