Most 3D printers, laser cutters, and inexpensive desktop CNC mills operate completely without feedback. The controller simply tells the stepper motors how far they should move, and hopes that they do. That’s fine as long as nothing goes wrong, but as soon as they miss a step or two your part is ruined. uStepper’s new S line of products fixes that by building an encoder directly into the stepper driver.
With the encoder integrated into the stepper driver, uStepper knows both the position the motor’s rotor should be in and where it actually is. If the stepper motor misses a step, uStepper will automatically compensate. Essentially, it’s a stepper motor driver that converts any open-loop system, like a 3D printer, into a closed-loop system. That’s possible because of the on-board encoder, and an Arduino-compatibleATmega328P microcontroller that constantly monitors it.
A closed-loop feedback system is only as good as the resolution of the encoder, and the speed at which it can be sampled. The most basic uStepper, the S-lite, has an encoder with a resolution of 0.088 degrees. The heavy duty S and S10 models have a resolution of 0.0055, which should exceed the microstepping capabilities of most stepper motors. Both can sample the encoder at 200kHz, and because that’s built into the driver it can scale to as many stepper motors as you need.
The uStepper S line Kickstarter campaign is running until September 13th. The S-lite without a stepper motor is about $40, the S is $51, and the S10 will become available if the stretch goal is reached. Delivery is expected in November.