controller.Controller Class Reference

A state machine to control a motor using PID. More...

Public Member Functions
def	__init__ (self, motor, encoder, closedLoop, state=0)
	Method to initialise a Controller object. More...
def	runStateMachine (self)
	A method that runs through the logic of the controller state machine once.
def	transitionStates (self, state, transition=True)
	A method that changes the state machine state, self.state and prints the state transition message. More...
def	pointControl (self, pos, vel)
	A method to calculate the motor PWM to get to a given position and velocity. More...
def	update (self)
	A method to check the encoder position and velocity.
def	getNextReferencePosition (self, file)
	A method that updates self.referencePoint to the next line in the reference csv. More...
def	step (self, magnitude, timeOut, delayms=20)
	Method to subject the motor to a step function. More...
def	selfTune (self, pos, vel, timeOut=5, delayms=20, pIn=1, iIn=0.01)
	Method to self tune the PI gains. More...

Public Attributes
	motor
	The Motor object to control.
	encoder
	The Encoder object to get feedback from the motor.
	closedLoop
	The ClosedLoop object to calculate closed loop control PWM level.
	state
	The current state of the state machine.
	position
	The position of self.motor.
	targetPosition
	The current target position for the motor.
	velocity
	The current velocity of self.motor.
	targetVelocity
	The current target velocity of the motor.
	prevTime
	The last time (in ms from startup) that self.update() was called.
	lastTransition
	The last time (in ms from startup) that the state machine transitioned states.
	referenceFile
	The .csv reference file of format time(s), velocity (rpm), position (deg) to control the motor to.
	referencePoint
	The current point reference point, format [time, velocity, position].

Static Public Attributes
dictionary	stateMessages
	A Dictionary of messages to display at each state change. More...

Detailed Description

A state machine to control a motor using PID.

The controller task is a state machine that uses closed loop feedback from an encoderDriver.encoder object to move a motor, controlled using a motorDriver.motor object along a reference path and velocity. The controller task also has several methods, controller.Controller.selfTune, step, and ramp, for automatically tunning the PID gains and are not implemented as part of the state machine. These methods are only for debugging and tuning and should not be run with this, or any other state machine, as they will pause the program until complete. Link to source code: https://bitbucket.org/ebriefer/me305_lab/src/master/Final%20Project/controller.py

Constructor & Destructor Documentation

__init__()

def controller.Controller.__init__	(		self,
			motor,
			encoder,
			closedLoop,
			state = 0
	)

Method to initialise a Controller object.

Parameters

motor	A Motor object to control.
encoder	An Encoder object to get feedback from the motor.
closedLoop	A ClosedLoop object to calculate the needed motor PWM level.
state	The initial state to start the state machine in.

Member Function Documentation

getNextReferencePosition()

def controller.Controller.getNextReferencePosition	(		self,
			file
	)

A method that updates self.referencePoint to the next line in the reference csv.

Parameters

file	The File object to read from, should be a .csv of the same format as self.referenceFile.

pointControl()

def controller.Controller.pointControl	(		self,
			pos,
			vel
	)

A method to calculate the motor PWM to get to a given position and velocity.

Parameters

pos	The target position to move the motor to, in rotations.
vel	The target velocity to move the motor at, in rotations per second.

Returns

The motor PWM level, from -100 to 100 (or capped at self.closedLoop saturation level)

selfTune()

def controller.Controller.selfTune	(		self,
			pos,
			vel,
			timeOut = 5,
			delayms = 20,
			pIn = 1,
			iIn = 0.01
	)

Method to self tune the PI gains.

This method is not implemented for use in a state machine and should not be run in conjucntion with any state machines. This method is only for testing and tuning.

Parameters

pos	The magnitude of the step function used for tuning Kp, in rotations.
vel	The magnitude of the ramp function used for tuning Kd, in rotaions per second.
timeOut	The duration of each test, in seconds
delayms	The period to update the motor controler at, in ms
pIn	The initial Kp to guess. should be the minimum realistic Kp, not 0.
iIn	The initial Ki to guess. should be the minimum realistic Ki, not 0.

step()

def controller.Controller.step	(		self,
			magnitude,
			timeOut,
			delayms = 20
	)

Method to subject the motor to a step function.

This method is not implemented for use in a state machine and should not be run in conjucntion with any state machines. This method is only for testing and tuning.

Parameters

magnitude	The magnitude of the step function, in rotations.
timeOut	The durration to run the step function for, in seconds.
delayms	The period to update the motor control at, in ms.

Returns

The J value of the controler's step response'

transitionStates()

def controller.Controller.transitionStates	(		self,
			state,
			transition = True
	)

A method that changes the state machine state, self.state and prints the state transition message.

Parameters

state	The state to transition to.
transition	A boolean for wether or not to transition, if False no transition will occur.

Member Data Documentation

stateMessages

dictionary controller.Controller.stateMessages

static

Initial value:

=  {0 : 'State 0: startup',
                     1 : 'State 1: Enabled',
                     2 : 'State 2: Wating',
                     3 : 'State 3: Reseting',
                     4 : 'State 4: Error'}

A Dictionary of messages to display at each state change.

---

The documentation for this class was generated from the following file:

• controller.py