Thanks!  I am working on a stepper motor version of the gearbox as another option.  I posted a comment/question in the Stepper servo Skill post but have not been provided an answer yet.  If you have used that skill maybe you could help answer the question @EzAng.

A great site to understand steppers is https://dronebotworkshop.com/stepper-motors-with-arduino/

you said:

Quote:

My goal is to develop a generic gearbox with a ARDUINO, Stepper Driver and Hall Effect sensor in one package that can be set to find home and then use the skill to set the range of motion the stepper motor can move.

https://dronebotworkshop.com/stepper-motor-hall-effect/

there is other stepper motors info there on the site

The step sequences were my problems, but I resolved it

I did get them moving forward and reverse

both the Bipolar Stepper, NEMA 17 with L298N H-Bridge and the 28BYJ-48 Unipolar Stepper with ULN2003 motor driver

the wiring - "step sequence" in the code was the problem at first

My 28BYJ-48 Unipolar stepper motor has a "step sequence" as: 1-3-2-4 or In the code I used 2-4-3-5

in the code it was #define STEPPER1_WIRE1 2 #define STEPPER1_WIRE2 4 #define STEPPER1_WIRE3 3 #define STEPPER1_WIRE4 5 AccelStepper stepper1(AccelStepper::FULL4WIRE, STEPPER1_WIRE1, STEPPER1_WIRE2, STEPPER1_WIRE3, STEPPER1_WIRE4);

Here is my connection, it works both directions

I n1 = 2 pin I n2 = 3 pin I n3 = 4 pin I n4 = 5 pin

*Note: The step sequence for a Bipolar Stepper, NEMA 17 with L298N H-Bridge is 1-2-3-4, a step instance with this in mind.

I have completed the modified V2 hand new wrist and lower forearm of the new arm and it works great using the JX PDI-1109MG micro servos in the lower section of the forearm I am very happy with it. You can view the video here https://youtube.com/shorts/vA_lxd-Cfow

Congrats! Creepy cool! Nice design.

It does look great. I always had problems with my inmoov hands. I would fine tune everything so the fingers would work perfectly then I would rotate the wrist a couple of times and it would be a mess afterwards. Have you actuated the wrist yet to see how that works? I recall you saying you were going to try to put the servos directly in the hand. Still considering that?

Perry,  I did work with Gael on adding the servos in the hand and after a change to his adapter to support the JX PDI-1109MG servos I did confirm that they do work and you get a full range of motion with them.  But with feedback from you and others putting the added weight in the hands was not a good idea.  So with that in mind I wanted to move them as far up the arm as I could.   To answer your question yes I can work the wrist and the hand works ok afterward.  But keep in mind my wrist does not rotate it bends up and down in my new arm the forearm rotates.  I have looked at another wrist that would require two servo's and more strings but it would provide up and down and side to side movement which would cover all the movement of a human forearm and wrist.  I just did not know if I could get everything in the lower arm.

Who knows I may come back and do that at some point.   My real goal is to make sure I come up with a stronger and faster shoulder.

I have been working on the shoulder 30:1 gearbox using a nema 17 the below is a picture of the planed design.  It will be using: 1-DRV8825/A4988 Stable 42 Stepper Motor Driver Expansion Board.  1-DRV8825 driver. 1-Seeed Studio XIAO SAMD21The Smallest Arduino Microcontroller Based on SAMD21,with Rich Interfaces, 100% Arduino IDE Compatible. 1-Mini MP1584EN DC-DC Buck Converter 1-Nema 17 Stepper Motor 1PC/3PCS/5PCS, 2 Phase Step Motor Bipolar 1.5A 59.5oz.in(42Ncm) 42x42x38mm 4-Wire 1-Hall Effect Magnetic Sensor Module 3144E A3144 Hall Effect Sensor DC 5V for Arduino. 1-3x1.5mm disk Magnet

The goal will be to provide 12V DC and USB connection from my LattePanda for to the first gear box on the BUS. Then for all other gearbox's the connection will be 12V sharing the same GND for motors on the serial BUS and the serial BUS wire from the TX on motor #1 to the RX on all other steppers on the BUS.

here is a picture of it mounted on the stepper motor.

Great job so far,

question, what string or cord did you use on the fingers?

EzAng