But the internal wiring of the 28BYJ-48 stepper motors isn’t compatible with the A4988.
#Robot stepper motor driver
The A4988 stepper motor driver works really nicely with grbl. The next problem had to do with the stepper motor & stepper driver-IC combination. Luckily, there’s a 4-axis fork of grbl here. The grbl, as awesome as it is, doesn’t support more than 3-axis out of the box. But – as so often when tinkering with stuff -yet another problem materialized. Because grbl will produce an accelerating series of pulses for you. To accomplish this, I decided to use the grbl. The problem now is to send steps in such a way that the stepper motor will be starting/stopping smoothly. Stepper motors are great because you can tell them how far to turn in “steps” (strictly speaking it’s the stepper’s driver-IC you tell how many steps to move). Speed isn’t important.Īnd here’s where the next hurdle came into view. We want the robot arm to be moving in an elegant fashion. But the speed loss isn’t even a downside since we don’t really care about it in this project. The only downside is the loss in speed (and maybe the mechanical play induced by the gear). It improves not only the precision (degrees/step getting smaller) but also increases the output torque. The fact that there’s a 1:64 gear built into housing is huge. Then I stumbled upon this extremely cheap gear-headed stepper motor which goes by the name “28BYJ-48”.
I wasn’t able to get satisfactory results, and as so often, I started doing other things and forgot about this project.
I tried an approach to re-implement the servo’s controller by getting rid of the microcontroller in the servo and just using the driver-IC and potentiometer output in combination with an Arduino Nano. The problem with servos is, that it is very hard to get them to move slowly/smoothly. Having seen this video, I tried for a while to do build a similar robot arm with the same servos. It is quite a masterpiece in both video editing and electronics craftsmanship. Some years ago I watched a YouTube video about a micro servo robot arm.
0 kommentar(er)
