MotorControl

MotorControl

Contains all functionality for controlling a PWM motor and reading an optional encoder for that motor. Also has functionality for controlling a commanded speed (PI loop).

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Goal

Motor-specific class

Meaning that a motor is treated as an object and the encoder data of that motor, as well as ramping and commanding the motor’s speed, is all accomplished inside MotorControl.

• Pass in the motor type on instantiation
• BSN values are calculated inside the motor object
• Used for special motors as well
• To be used for the flywheel motors on the quarterback as well

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Scope

• Generic motor class, to be used with ALL motors, special and drive
• Useful for closed-loop motors and actuators
• Anything that requires more than one motor is outside this scope

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Milestones

Initial Implementation

• Need to test how Sabertooth responds to the PWM input
• Need to associate an RPM to a motor percent value
• Functions to convert % to RPM and RPM to % — needs to be public
• Move in working encoder code from
  PR-Sandbox/Encoder-Code-Testing → ESP32PRCodebase/dev/motor-feedback
• Class needs to store and do necessary logic related to MotorType
• Ramp to be refactored to work with RPM and take an acceleration value input, and moved to MotorControl, as the function is motor-dependent

PI Loop Implementation

• The PI loop will reside here
• Gains to be tuned and stored in a lookup table determined by the robot index in the array
• This can also just be dependent on the MotorType

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Breakdown

Inputs

• MotorPins (from PolarRobotics.h → Drive.cpp)
• Encoder Pins (default to -1 for no encoder)
• MotorType (from RobotConfig)
• Gear Ratio (from RobotConfig)
• Commanded Motor Power or Percent Power
• Override for BSN-selected motor power for cases with special motors

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Functions

Private:

• ramp()

Public:

• commandMotorRPM(float pct, bool use_ramp)

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Details

• Entire closed-loop system, motor-specific
• Goal is to command a motor to a given RPM and have the PI loop achieve that RPM
• Move control elements (encoder reading and motor-related code) to a specific MotorControl class
• Handles commands to the motor and encoder values from the wheel

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Example Function Calls

M1.write(-1);
float speed = M1.getSpeed();

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Links

• [Microcontroller I/O ADC Benchmarks – Arduino Forum](https://forum.arduino.cc/t/microcontroller-i-o-adc-benchmarks/315304/33)
• [ESP32 Interrupts Tutorial – Upesy](https://www.upesy.com/blogs/tutorials/what-are-interrupts-in-esp32-with-examples-for-arduino-code#:~:text=The%20use%20of%20interrupts%20on,any%20GPIO%20pin%20for%20interrupts.&text=It%20is%20recommended%20to%20add,that%20the%20function%20runs%20faster)
• [PID Loops: A Comprehensive Guide – Wevolver](https://www.wevolver.com/article/pid-loops-a-comprehensive-guide-to-understanding-and-implementation)
• [Introduction to PID Control Loops – Erdos Miller](https://info.erdosmiller.com/blog/introduction-to-pid-control-loops)
• [Introduction to PID Controllers (2nd Edition) – George Gillard](https://georgegillard.com/component/osdownloads/routedownload/robotics/introduction-to-pid-controllers-2nd-edition)

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Comments

RD:
A simple implementation of PID for an inverse kinematic ball balancer project:
Ball-Balancer-V2/Ball_Balancing.ino at main · aaedmusa/Ball-Balancer-V2

GB:
Attach interrupt to A channel and have it digitally read B channel to determine direction. We are fairly confident that read time will not be a problem.

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Start by reading the existing motor and encoder code referenced in PR-Sandbox/Encoder-Code-Testing and ESP32PRCodebase/dev/motor-feedback, along with MotorPins in PolarRobotics.h, Drive.cpp, and MotorType in RobotConfig. The issue calls for a broad MotorControl design covering PWM, encoders, RPM conversion, ramping, and a PI loop; done means these milestones are implemented for generic and special motors and validated on the Sabertooth hardware.