Motion Control System

I’m looking into building a table top 7-8 axis motion control rig to achieve some specific macro VFX shots I need for a project and I’m considering using TD to drive the stepper motors and servos since it will let me easily build a programming UI and integrated previz environment. Precision is going to be very important so I was wondering whether anyone has had success interfacing TD with any specific server or stepper motor driver/controller hardware? I’ve been looking at the Pololu units thus far.

Yeah! It’d probably be a good idea to have a separate system actually monitoring the axes, with TD either uploading a timeline to it, or jogging the external system which will then control the axes directly or run its own PID loop and give you measured position feedback for post.

You don’t really want to be directly running the PID loop or stepper control inside TD, which might only update at 30-100fps depending on your setup. And, even though they’re smallish motors, it’s wise to have a separate system monitoring itself to stop motion in case TD loses the connection, one of the motors fails, one of the motors runs away, or something gets in the way of a motor. For what you’re describing, an Arduino or two via serial would probably do a fine job. If you’re dealing with something more complex, maybe an industrial motion controller with an RS232/RS485/Ethernet interface. Definitely a physical button or switch to kill power in an emergency, even if its as simple as a beefy power strip with a switch in reach of the operator.

Thanks for the advice. I just ordered enough parts to build a 4-axis (pan, tilt, slider, focus) system as a proof of concept. I’m going to drive it off of a Pololu Maestro 18-channel USB servo controller which offers a Python library that offloads most of the control work the controller and should be easy enough to integrate with TD. I definitely, will have a hard-wired E-stop on the power to the system. If I end up stepping up to a physically larger system I’ll move over to an industrial grade motion controller/PLC which TD will drive over RS232.

Looks like a solid plan!

Hi Matthewh how are you?
I am working on a project which involves the same request you asked. I need to control a precised step motor for macroshots and vfx on one axis and need an UI to sychronisz shapes postions with the motor position.

Could you help me?