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.

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)
void initPid(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 – The max integral windup.

  • i_min – The min integral windup.

  • antiwindup – antiwindup.

bool initPid()

Initialize the PID controller based on already set parameters.

Returns:

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

void reset()

Reset the state of this PID controller.

double computeCommand(double error, 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 computeCommand(double error, double error_dot, 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 getGains()

Get PID gains for the controller.

Returns:

gains A struct of the PID gain values

void setGains(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

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 – antiwindup.

void setGains(const Pid::Gains &gains)

Set PID gains for the controller.

Note

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

Parameters:

gains – A struct of the PID gain values

void setCurrentCmd(double cmd)

Set current command for this PID controller.

Parameters:

cmd – command to set

double getCurrentCmd()

Return current command for this PID controller.

Returns:

current cmd

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

Return PID state publisher.

Returns:

shared_ptr to the PID state publisher

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

Return PID error terms for the controller.

Parameters:

  • pe[out] – The proportional error.

  • ie[out] – The integral error.

  • de[out] – The derivative error.

void printValues()

Print to console the current parameters.

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

Return PID parameters callback handle.

Returns:

shared_ptr to the PID parameters callback handle

Protected Attributes

std::string topic_prefix_
std::string param_prefix_