Class PidROS

Class Documentation

class PidROS

Public Functions

template<class NodeT>
inline explicit PidROS(std::shared_ptr<NodeT> node_ptr, std::string prefix = std::string(""), bool prefix_is_for_params = false)

Constructor of PidROS class.

The node is passed to this class to handler the ROS parameters, this class allows to add a prefix to the pid parameters

Parameters:

  • node – ROS node

  • prefix – prefix to add to the pid parameters. Per default is prefix interpreted as prefix for topics.

  • prefix_is_for_params – provided prefix should be interpreted as prefix for parameters. If the parameter is true then “/” in the middle of the string will not be replaced with “.” for parameters prefix. “/” or “~/” at the beginning will be removed.

template<class NodeT>
inline explicit PidROS(std::shared_ptr<NodeT> node_ptr, const std::string &param_prefix)
template<class NodeT>
inline explicit PidROS(std::shared_ptr<NodeT> node_ptr, const std::string &param_prefix, const std::string &topic_prefix)

Constructor of PidROS class.

The node is passed to this class to handler the ROS parameters, this class allows to add a prefix to the pid parameters

Parameters:

  • node – Any ROS node

  • param_prefix – prefix to add to the pid parameters.

  • topic_prefix – prefix to add to the state publisher. If it starts with ~/, topic will be local under the namespace of the node. If it starts with / or an alphanumeric character, topic will be in global namespace.

template<class NodeT>
inline explicit PidROS(std::shared_ptr<NodeT> node_ptr, std::string param_prefix, std::string topic_prefix, bool activate_state_publisher)

Constructor of PidROS class.

The node is passed to this class to handler the ROS parameters, this class allows to add a prefix to the pid parameters

Parameters:

  • node – Any ROS node

  • param_prefix – prefix to add to the pid parameters.

  • topic_prefix – prefix to add to the state publisher. If it starts with ~/, topic will be local under the namespace of the node. If it starts with / or an alphanumeric character, topic will be in global namespace.

  • activate_state_publisher – If true, the publisher will be enabled after initialization.

PidROS(rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_base, rclcpp::node_interfaces::NodeLoggingInterface::SharedPtr node_logging, rclcpp::node_interfaces::NodeParametersInterface::SharedPtr node_params, rclcpp::node_interfaces::NodeTopicsInterface::SharedPtr topics_interface, std::string prefix = std::string(""), bool prefix_is_for_params = false)
PidROS(rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_base, rclcpp::node_interfaces::NodeLoggingInterface::SharedPtr node_logging, rclcpp::node_interfaces::NodeParametersInterface::SharedPtr node_params, rclcpp::node_interfaces::NodeTopicsInterface::SharedPtr topics_interface, const std::string &param_prefix, const std::string &topic_prefix, bool activate_state_publisher)

Constructor of PidROS class with node_interfaces.

Parameters:

  • node_base – Node base interface pointer.

  • node_logging – Node logging interface pointer.

  • node_params – Node parameters interface pointer.

  • topics_interface – Node topics interface pointer.

  • param_prefix – Prefix to add to the PID parameters. This string is not manipulated, i.e., probably should end with ..

  • topic_prefix – Prefix to add to the state publisher. This string is not manipulated, i.e., probably should end with /. If it starts with ~/, topic will be local under the namespace of the node. If it starts with / or an alphanumeric character, topic will be in global namespace.

  • activate_state_publisher – If true, the publisher will be enabled after initialization.

bool initialize_from_args(double p, double i, double d, double i_max, double i_min, bool antiwindup)

Initialize the PID controller and set the parameters.

Note

New gains are not applied if i_min_ > i_max_

Parameters:

  • p – The proportional gain.

  • i – The integral gain.

  • d – The derivative gain.

  • i_max – Upper integral clamp.

  • i_min – Lower integral clamp.

  • antiwindup – Anti-windup functionality. When set to true, limits the integral error to prevent windup; otherwise, constrains the integral contribution to the control output. i_max and i_min are applied in both scenarios.

Returns:

True if all parameters are successfully set, False otherwise.

bool initialize_from_args(double p, double i, double d, double i_max, double i_min, bool antiwindup, bool save_i_term)

Initialize the PID controller and set the parameters.

Note

New gains are not applied if i_min_ > i_max_

Parameters:

  • p – The proportional gain.

  • i – The integral gain.

  • d – The derivative gain.

  • i_max – The max integral windup.

  • i_min – The min integral windup.

  • antiwindup – Anti-windup functionality. When set to true, limits the integral error to prevent windup; otherwise, constrains the integral contribution to the control output. i_max and i_min are applied in both scenarios.

  • save_i_term – save integrator output between resets.

Returns:

True if all parameters are successfully set, False otherwise.

bool initialize_from_args(double p, double i, double d, double u_max, double u_min, const AntiWindupStrategy &antiwindup_strat, bool save_i_term)

Initialize the PID controller and set the parameters.

Note

New gains are not applied if u_min_ > u_max_.

Parameters:

  • p – The proportional gain.

  • i – The integral gain.

  • d – The derivative gain.

  • u_max – Upper output clamp.

  • u_min – Lower output clamp.

  • antiwindup_strat – Specifies the anti-windup strategy. Options: ‘back_calculation’, ‘conditional_integration’, or ‘none’. Note that the ‘back_calculation’ strategy use the tracking_time_constant parameter to tune the anti-windup behavior.

  • save_i_term – save integrator output between resets.

Returns:

True if all parameters are successfully set, False otherwise.

bool initialize_from_ros_parameters()

Initialize the PID controller based on already set parameters.

Returns:

True if all parameters are set (p, i, d, i_max, i_min, u_max, u_min), False otherwise

Returns:

False if the parameters are not set or if the parameters are invalid

void reset()

Reset the state of this PID controller.

Note

save_i_term parameter is read from ROS parameters

void reset(bool save_i_term)

Reset the state of this PID controller.

Parameters:

save_i_term – boolean indicating if integral term is retained on reset()

double compute_command(double error, const rclcpp::Duration &dt)

Set the PID error and compute the PID command with nonuniform time step size. The derivative error is computed from the change in the error and the timestep dt.

Parameters:

  • error – Error since last call (error = target - state)

  • dt – Change in time since last call in seconds

Returns:

PID command

double compute_command(double error, double error_dot, const rclcpp::Duration &dt)

Set the PID error and compute the PID command with nonuniform time step size. This also allows the user to pass in a precomputed derivative error.

Parameters:

  • error – Error since last call (error = target - state)

  • error_dot – d(Error)/dt since last call

  • dt – Change in time since last call in seconds

Returns:

PID command

Pid::Gains get_gains()

Get PID gains for the controller.

Note

This method is not RT safe

Returns:

gains A struct of the PID gain values

bool set_gains(double p, double i, double d, double i_max, double i_min, bool antiwindup = false)

Set PID gains for the controller.

Note

New gains are not applied if i_min > i_max

Note

This method is not RT safe

Parameters:

  • p – The proportional gain.

  • i – The integral gain.

  • d – The derivative gain.

  • i_max – Upper integral clamp.

  • i_min – Lower integral clamp.

  • antiwindup – Antiwindup functionality. When set to true, limits the integral error to prevent windup; otherwise, constrains the integral contribution to the control output. i_max and i_min are applied in both scenarios.

Returns:

True if all parameters are successfully set, False otherwise.

bool set_gains(double p, double i, double d, double u_max, double u_min, const AntiWindupStrategy &antiwindup_strat)

Set PID gains for the controller (preferred).

Note

New gains are not applied if u_min_ > u_max_.

Note

This method is not RT safe

Parameters:

  • p – The proportional gain.

  • i – The integral gain.

  • d – The derivative gain.

  • u_max – Upper output clamp.

  • u_min – Lower output clamp.

  • antiwindup_strat – Specifies the anti-windup strategy. Options: ‘back_calculation’, ‘conditional_integration’, or ‘none’. Note that the ‘back_calculation’ strategy use the tracking_time_constant parameter to tune the anti-windup behavior.

Returns:

True if all parameters are successfully set, False otherwise.

bool set_gains(const Pid::Gains &gains)

Set PID gains for the controller.

Note

New gains are not applied if gains.i_min_ > gains.i_max_

Note

This method is not RT safe

Parameters:

gains – A struct of the PID gain values

Returns:

True if all parameters are successfully set, False otherwise.

void set_current_cmd(double cmd)

Set current command for this PID controller.

Parameters:

cmd – command to set

double get_current_cmd()

Return current command for this PID controller.

Returns:

current cmd

std::shared_ptr<rclcpp::Publisher<control_msgs::msg::PidState>> get_pid_state_publisher()

Return PID state publisher.

Returns:

shared_ptr to the PID state publisher

void get_current_pid_errors(double &pe, double &ie, double &de)

Return PID error terms for the controller.

Parameters:

  • pe[out] – The proportional error.

  • ie[out] – The weighted integral error.

  • de[out] – The derivative error.

void print_values()

Print to console the current parameters.

inline rclcpp::node_interfaces::OnSetParametersCallbackHandle::SharedPtr get_parameters_callback_handle()

Return PID parameters callback handle.

Returns:

shared_ptr to the PID parameters callback handle

Protected Attributes

std::string topic_prefix_
std::string param_prefix_