Class PID

• Defined in File pid.h

Class Documentation

class PID

Public Functions

PID(double p, double i, double d, double i_max, double i_min)

Constructor.

Parameters

• p – proportional gain

• i – integral gain

• d – derivative gain

• i_max – integral wind-up max value

• i_min – integral wind-up min value

PID()

Constructor. Starts all gains and limits at zero.

bool init(const std::string &name, rclcpp::Node::SharedPtr node)

initialize gain settings from ROS parameter values

void reset()

Reset integral wind-up term.

double update(double error, double dt)

Run PID calculation and return control result.

PID derivate term is calculated from change in error value and dt

Parameters

• error – error term (goal-actual)

• dt – timestep used for calculating derivative term and integral windup

Returns

calculated PID command

double update(double error, double error_dot, double dt)

Run PID calculation and return control result.

Parameters

• error – error term (goal-actual)

• error_dot – value that is used for derivative term calculation

• dt – timestep used for integral windup

Returns

calculated PID command

Protected Functions

bool checkGains()

Checks and fixes gain settings.

Returns

true is gains are ok, false if gains are invalid

Protected Attributes

double p_gain_

proportial gain

double i_gain_

integral gain

double d_gain_

derivative gain

double i_max_

integral gain min and max limits

double i_min_

double i_term_

integral wind-up term

double error_last_

Last error value, used for calculating error_dot when not provided.

rclcpp::Node::SharedPtr node_