Hello! I am planning to build a robotic arm (5 or 6 dof) with stepper motors (probably NEMA 17) which I want to be closed loop.
The budget is up to 30$ per closed loop stepper motor (motor + driver + encoder). In addition I will need a motherboard to control them. What option are there?

As you understand, at this budget I am looking for Chinese products and not the more expensive options like (original) Mechaduino, ustepper etc.
From what I have found so far (if there any mistakes please correct me):

1. MKS Servo42B (cpu: STM32 F103 C8T6, driver: A4954 , encoder: A1333LLETR-T) + MKS Gen 1.4 (~ $20 + $18)
2. BIGTREETECH S42B (cpu: STM32 F030 C8T6, driver: 2xA4950T, encoder: TLE5012B ) + SKR V1.4 (~ $24 + $21)

(I couldn't find any info on the steppers motors they use, torque etc., besides that they are nema17).

There is also the clone of Mechaduino 0.2 (with AS5047D encoder), but the board alone costs $24 and with a cheap nema17 I probably could make it below $35. But still it is a more expensive option and I am not sure if it is worth it.

Instead of using their motherboards I could (and would prefer to) use Arduino Mega 2560 + RAMPS 1.4/1.5/1.6 + Servo42B or S42B (is it even possible)?

Another option is to build it from scratch myself, e.g. Arduino Mega 2560 + RAMPS 1.4/1.5/1.6 + stepper motors + drivers (e.g. A4988, DRV8825) + encoders (e.g. AS5047P, AS5047D, AS5048A, TLE5012B ) + microcontrollers (e.g. STM32), but this is much more difficult to do for a beginner like me.

Any suggestions are welcome.

Edited 22 time(s). Last edit at 02/27/2020 03:07AM by kuan.

So there are two versions of Servo42, A and B. Here is the comparison of the two:



Is the version B closed source as it says? Does it have usb? And what is the role of the serial port? From this comparison (if it's correct) it seems that I will prefer the A.

Edited 3 time(s). Last edit at 02/27/2020 03:24AM by kuan.

You haven't said what you are going to do with your creation. To make design decisions you have to start by defining what the end result needs to do.
"ready! Fire! Aim!" is going to lead to disappointment.
We cant help you until you have made those decisions.

DLC

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Quote
dlc60
You haven't said what you are going to do with your creation. To make design decisions you have to start by defining what the end result needs to do.
DLC

You are right! I am a beginner in robotics and want to build a robotic arm without a specific application in mind. The main goal is to learn by building it and then play by programming it to do fun stuff like playing chess, picking objects (1-2 kg).

It would be great to build a closed-loop stepper motor from scratch, i.e. stepper-motor + drivers (e.g. A4988, DRV8825) + encoders (e.g. AS5047P, AS5047D, AS5048A, TLE5012B ) + microcontrollers (e.g. STM32). But that seems like a very difficult task to do and requires a lot of programming as well. Are you aware of any such diy projects that I could follow?

Edited 1 time(s). Last edit at 02/28/2020 07:39AM by kuan.

I m currently experimenting with s42b v2.0 and arduino mega+ ramps on a 6dof robotic arm on ros... if you need only to take correct / expected steps by a closed loop system, than just installl the s42b pcb , the closed loop routine is fully standalone. If you need to get current position or different data from closed loop system... than you ll need to start programming (v2.0 have canbus option to send and receive all data from/to closed loop stepper motor). take a look to niryo_one - learning mode and how this function work manually moving the arm by hands than save the currentposition to allow him to learn and than execute itself...

Edited 1 time(s). Last edit at 04/03/2021 10:14AM by nasoftz.