Move a Camera in Four Axes with This Custom Motion Control Rig
See how one maker was able to construct a custom camera rig that can move in up to four axes for the smoothest shots.
In the field of cinematography, getting those crisp and smooth camera movements presents quite a challenge. Often, camera operators will wear large backpacks that attempt to remove some of the weight from the user's arms, or cameras are set onto rails. But these solutions still require a human operator or can move in a limited number of ways. The alternative is getting a large cinema robotic arm that costs upwards of 50 to 100 thousand dollars.
Andreas Epp has created a viable solutions to these problems that doesn't cost too much by building his own motion control rig to move around his DSLR for capturing smooth videos in up to four axes of motion.
The mechanics
Robots are complex, and constructing one that is able to hold and maneuver something as heavy as a DSLR presents an even greater challenge. To support this weight, the core of the rig is comprised of two rings, forming a gimbal. The one on the left rotates about the X axis, providing pitch, while the one above rotates around the Z axis for yaw control. The entire assembly is then mounted onto a rail that extends fairly far out for a linear panning motion. The final axis is actually an entirely separate turntable that just spins the object of focus. To prevent cables from getting tangled whilst the gimbals rotate, the rings have an inlaid slip-ring that houses a pair of concentric rings with 12 channels of conductors, which lets them rotate in a single direction indefinitely.
Circuit design
As one might imagine, a device with this kind of motion requires several motors to make that happen. Each axis is controlled with a single stepper motor that's attached to a GRBL shield on top of an Arduino Uno. Because steppers can only position themselves relatively, they need an external way to know what their home positions are. To do this task, Epp placed an opto-interrupting board on each axis that uses an emitter and detector to signal when the end stop piece is present.
Programming
The Uno runs a piece of firmware called GRBL that takes in GCODE commands from the serial port and translates them to stepper movements. A Raspberry Pi hosts the software for the camera controller rig. It uses NodeJS to run a simple Node-RED service that connects to the Arduino Uno and retrieves keyframe commands from files. The Pi is also connected to an LCD so users can always know what their device is doing.
How well does it work?
This project's video showcases just how powerful and versatile the camera rig is. You can see the camera move and whir into various positions for capturing incredible shots that would otherwise be very difficult to pull off.