This is a step-by-step, 4 axis, velocity controlled robot arm controller using the Arduino IDE and an M5Stack M5StickC Plus.
It plays back a sequence of arm positions in a loop, smoothly accelerating and decelerating to prevent the robot arm jerking.
YouTube video : https://www.youtube.com/watch?v=A6L-htjksoE
Hardware:
A 3D printer. (You can find people who print the models online if you don't have one)
Shop bought arm: https://www.banggood.com/Small-Hammer-3D-Print-DIY-4DOF-RC-Robot-Arm-Kit-With-SG90-Servos-p-1451689.html
3D printer files for robot arm: https://www.thingiverse.com/thing:65081
M5StickC Plus: https://shop.m5stack.com/products/m5stickc-plus-esp32-pico-mini-iot-development-kit
I2C C-Back driver board: https://shop.m5stack.com/products/c-back-hat-with-servo-driver-stm32f0
For the power supply (4 servos flatten the M5Stick battery quite fast!):
Rounded vero-board: https://www.amazon.co.uk/gp/product/B07G5CP6G2/
Micro USB breakout: https://www.amazon.co.uk/WayinTop-Pinboard-Breakout-Converter-Breadboard/dp/B07W13X3TD/
Wire up the servo power pins to the USB +5/GND volts as well as the ground of the C-Back driver. Wire up the signal pins from the M5Stick through the board to the servos.
Software:
Servo velocity control (already included): https://wired.chillibasket.com/2020/05/servo-trajectory/
This project.