wpid::PID Class Reference

A PID class that stores constants and calculates the speed of a motor or motor group with respect to its current error and other internal factors. More...

#include <PID.h>

Public Member Functions
	PID (float kp, float ki, float kd)
	Construct a new PID object. When constructing a PID object, only the kp constant is required, ki and kd can be set to 0 if not used.
float	calculateSpeed (float error, float max_speed, std::string mech_id)
	Used to calculate the velocity of a motor or motor group. The speed is calculated using PID, with integral clamping, and speed clamping.
void	setErrorRange (float degrees)
	Set the error range in rotationUnits::deg.
int	getDelayTime ()
	Gets the delay time of this PID object in milliseconds.
void	setLowSpeedThreshold (int threshold)
	Set the low speed threshold to determine when the system is slow. If the speed of the system is below this threshold, the loop will end if it is also within the error range. Otherwise the system will continue to correct for any error.
void	setTimeout (int timeout)
	Set the timeout to use for PID movement. If the timeout is exceeded, the system will stop regardless of the current error or speed. A value of -1 will disable timeouts.
void	setMaxIntegral (int max_integral)
	Set the maximum value the integral term will contribute to the speed calculations. If the integral term exceeds this value, it will be reduced to this value.
bool	unfinished (float error, int speed)
	Checks if the movement is unfinished (error still outside the final bounds).
void	reset (void)
	Resets the previous error and previous integral values.
PID	copy (void)
	Duplicates the PID object by copying constants and returning a new PID object. Used as a helper for using the same constants on multiple mechanisms.
void	fileLogging (float error, float speed, float proportional, float integral, float derivative, std::string mech_id)
	Logs the error, speed, integral and derivative values to a text file on a micro SD card on the robot.

Detailed Description

A PID class that stores constants and calculates the speed of a motor or motor group with respect to its current error and other internal factors.

Constructor & Destructor Documentation

PID()

wpid::PID::PID ( float  kp, float  ki, float  kd  )

inline

Construct a new PID object. When constructing a PID object, only the kp constant is required, ki and kd can be set to 0 if not used.

Parameters

kp	proportional constant
ki	integral constant
kd	derivative constant

Member Function Documentation

calculateSpeed()

float PID::calculateSpeed	(	float	error,
		float	max_speed,
		std::string	mech_id
	)

Used to calculate the velocity of a motor or motor group. The speed is calculated using PID, with integral clamping, and speed clamping.

Parameters

error	the remaining distance to the target
max_speed	maximum velocity allowed in velocityUnits::pct
mech_id	string identifier for motor group to log

Returns

a calculated speed based on all PID parameters

copy()

PID PID::copy

(

void

)

Duplicates the PID object by copying constants and returning a new PID object. Used as a helper for using the same constants on multiple mechanisms.

Returns

PID

fileLogging()

void PID::fileLogging	(	float	error,
		float	speed,
		float	proportional,
		float	integral,
		float	derivative,
		std::string	mech_id
	)

Logs the error, speed, integral and derivative values to a text file on a micro SD card on the robot.

Parameters

error	the robot error value
speed	the calculated speed
proportional	result of the proportional calculation
integral	result of the integral calculation
derivative	result of the derivative calculation
mech_id	the mechanism name

getDelayTime()

int PID::getDelayTime

(

)

Gets the delay time of this PID object in milliseconds.

Returns

int milliseconds

setErrorRange()

void PID::setErrorRange

(

float

degrees

)

Set the error range in rotationUnits::deg.

Parameters

degrees

the absolute value of the bounds of the error range

setLowSpeedThreshold()

void PID::setLowSpeedThreshold

(

int

threshold

)

Set the low speed threshold to determine when the system is slow. If the speed of the system is below this threshold, the loop will end if it is also within the error range. Otherwise the system will continue to correct for any error.

Parameters

threshold

in velocityUnits::pct

setMaxIntegral()

void PID::setMaxIntegral

(

int

max_integral

)

Set the maximum value the integral term will contribute to the speed calculations. If the integral term exceeds this value, it will be reduced to this value.

Parameters

max_integral

in velocityUnits::pct

setTimeout()

void PID::setTimeout

(

int

timeout

)

Set the timeout to use for PID movement. If the timeout is exceeded, the system will stop regardless of the current error or speed. A value of -1 will disable timeouts.

Parameters

timeout

in milliseconds

unfinished()

bool PID::unfinished	(	float	error,
		int	speed
	)

Checks if the movement is unfinished (error still outside the final bounds).

Parameters

error

the current error of the system

Returns

returns true if the error is outside the bounds, false if it is within the bounds

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

• include/WPID/PID.h
• src/WPID/PID.cpp