The goal of this project was to model, simulate and derive a control system for the position of a ball on a track thats angle is actuated by a motor.
SolidWorks model of ball and track, designed based on control system analysis
The first step was modelling the system dynamics. I calculated the Lagrangian equations, then linearized and Laplace transformed into the frequency domain.
I then modeled the system in MATLAB, allowing me to computationally tune a PD controller that satisfies my response time and robustness objectives.
Simulating gave peak torque and angular velocity values of about 27 N.cm and 17 rad/sec (~160RPM). I found a motor, the NEMA17 Stepper (17HS19), which satisfies these requirements, including a margin of safety of about 50%.
With the motor chosen, I picked components for the electrical system. I needed a stepper driver capable of supplying 2A, a sensor to measure the ball's position that's high resolution even at short distances, and an MCU fast enough to run the PD controller. This directed me towards the TMC2209 driver, the VL53L4CD Time of Flight sensor, and the SAMD21G18A Cortex M0+ processor on an Arduino development board. In Altium, I made the a circuit schematic.
Next is designing the software system architecture. Guided by the SOLID object oriented design principles, I'm making each component its own single-responsibility class. This manages complexity and allows for subsystem unit tests. The classes interact with each other as components through an event-driven framework, which allows concurrency despite there only being a single core on the Arm Cortex M0+ processor.
The full code (400+ lines) is at: https://github.com/jacoblgit/Ball-Beam-Robot/tree/cda9178c381dc9eee17660c450379591275cd431/code/Ball-Beam/src