How Accurate Is Microstepping Really?

Stepper motors divide a full rotation into hundreds of discrete steps, which makes them ideal to precisely control movements, be it in cars, robots, 3D printers or CNC machines. Most stepper motors you’ll encounter in DIY projects, 3D printers, and small CNC machines are bi-polar, 2-phase hybrid stepper motors, either with 200 or — in the high-res variant — with 400 steps per revolution. This results in a step angle of 1.8 °, respectively 0.9 °.

Can you increase the resolution of this stepper motor?

In a way, steps are the pixels of motion, and oftentimes, the given, physical resolution isn’t enough. Hard-switching a stepper motor’s coils in full-step mode (wave-drive) causes the motor to jump from one step position to the next, resulting in overshoot, torque ripple, and vibrations. Also, we want to increase the resolution of a stepper motor for more accurate positioning. Modern stepper motor drivers feature microstepping, a driving technique that squeezes arbitrary numbers of microsteps into every single full-step of a stepper motor, which noticeably reduces vibrations and (supposedly) increases the stepper motor’s resolution and accuracy.

On the one hand, microsteps are really steps that a stepper motor can physically execute, even under load. On the other hand, they usually don’t add to the stepper motor’s positioning accuracy. Microstepping is bound to cause confusion. This article is dedicated to clearing that up a bit and — since it’s a very driver dependent matter — I’ll also compare the microstepping capabilities of the commonly used A4988, DRV8825 and TB6560AHQ motor drivers.

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A Recycled Robot Arm For All!

It’s mind boggling how much e-waste we throw out. Perfectly good components, mass produced for pennies. And at the end of their life, going straight to a landfill or some poor country to be melted down. Don’t you wish you could help?

Stepper motors are a dime a dozen when it comes to e-waste, and there’s tons of cool projects you can do with a stepper motor — [Madivak] is just starting on a robot arm design over at Hackaday.io that makes use of recycled components.

It’s fairly early in development, but that means it’s a great time to start following it on the project site. The robotic arm is being designed for his final year project in his undergrad degree. Besides the steppers, he’s using his school’s Utilimaker 3D printer to manufacture all of the other mechanical components with control coming from DRV8825 stepper drivers and the Freescale Freedom KL25Z dev kit. Check out the clips after the break to see current state of the build.

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