An integrated solution to learn about control algorithms and how to design them!

Initially the first design phase for my robot arm project, I needed a way to test some generic motors and rotary encoders and ensure my control algorithms worked well with them. This has proven to be a very helpful tool to dive deeper into the engineering/physics/mathematical world of control. I thought I'd share this to be used as a learning aid for this topic.

Over the coming weeks I intend to update this and share some of the code I have been working on in terms of PID control and full state feedback control. Stay posted!

Why bother learning about control when you can just use a stepper motor or servo?

Control is a massive part of any industrial system from robot arms to conveyer belts to electric vehicles. Understanding how to use control algorithms well and the math behind them allows you to unlock DC motors for projects requiring precise movement and higher torque applications. You can tune your motor too prioritise accuracy and speed and minimise power consumption. Experiment with different arm weights and creating mathematical models for them, and tuning your control design.

These parts are readily available if you live in Australia, but may have to dig a little deeper elsewhere but they are pretty standard:

DC Motor: [https://core-electronics.com.au/metal-dc-geared-motor-12v-100rpm-42kg-cm.html](https://core-electronics.com.au/metal-dc-geared-motor-12v-100rpm-42kg-cm.html)

Rotary Encoder: [https://core-electronics.com.au/360-ppr-encoder.html](https://core-electronics.com.au/360-ppr-encoder.html)

You may also need a motor driver similar to this:

[https://core-electronics.com.au/2a-dual-motor-controller.html](https://core-electronics.com.au/2a-dual-motor-controller.html)

The electronics are relatively straight forward, please leave a message if you would like a detailed schematic but I'll write some basic instructions here:

1. Connect the 4 pins of your rotary encoder to 5V, GND, and any two GPIO. The two pins connected to GPIO will need a 1k pull-up resistor to 5V. These will also need to be level-shifted using a voltage divider or your preferred method if using a 3.3V computer or microcontroller like a Raspberry Pi or ESP32. Arduino UNO is fine :)
2. Connector two GPIO to the motor direction and motor enable pins on your driver. Use a PWM pin for the enable as this will control motor voltage.
3. Connect motor power (12V) to your driver, and your two motor wires to the driver. Your ready to go!

In terms of hardware, it all slots together pretty nicely, and is assembled using M3 and M5 screws:

• 6x M5 16mm
• 8x M5 12mm
• 14 x M5 Nut
• 9 x M3 6mm
• 4 x M3 20mm
• 4 x M3 Nut

The lengths are not too important, but be prepared to use some washers if they are too long.

Reach out with any questions or problems and I'd be more then happy to help!