Class ChainableControllerInterface

Inheritance Relationships

Base Type

Class Documentation

class ChainableControllerInterface : public controller_interface::ControllerInterfaceBase

Virtual class to implement when integrating a controller that can be preceded by other controllers. Specialization of ControllerInterface class to force implementation of methods specific for “chainable” controller, i.e., controller that can be preceded by an another controller, for example inner controller of an control cascade.

Public Functions

CONTROLLER_INTERFACE_PUBLIC ChainableControllerInterface()
virtual CONTROLLER_INTERFACE_PUBLIC ~ChainableControllerInterface() = default
virtual CONTROLLER_INTERFACE_PUBLIC return_type update (const rclcpp::Time &time, const rclcpp::Duration &period) final

Control step update. Command interfaces are updated based on on reference inputs and current states. The method called in the (real-time) control loop.

Parameters:

  • time – [in] The time at the start of this control loop iteration

  • period – [in] The measured time taken by the last control loop iteration

Returns:

return_type::OK if update is successfully, otherwise return_type::ERROR.

virtual CONTROLLER_INTERFACE_PUBLIC bool is_chainable () const final

Get information if a controller is chainable.

Get information if a controller is chainable.

Returns:

true is controller is chainable and false if it is not.

virtual CONTROLLER_INTERFACE_PUBLIC std::vector< hardware_interface::CommandInterface > export_reference_interfaces () final

Export interfaces for a chainable controller that can be used as command interface of other controllers.

Returns:

list of command interfaces for preceding controllers.

virtual CONTROLLER_INTERFACE_PUBLIC bool set_chained_mode (bool chained_mode) final

Set chained mode of a chainable controller. This method triggers internal processes to switch a chainable controller to “chained” mode and vice-versa. Setting controller to “chained” mode usually involves disabling of subscribers and other external interfaces to avoid potential concurrency in input commands.

Returns:

true if mode is switched successfully and false if not.

virtual CONTROLLER_INTERFACE_PUBLIC bool is_in_chained_mode () const final

Get information if a controller is currently in chained mode.

Get information about controller if it is currently used in chained mode. In chained mode only internal interfaces are available and all subscribers are expected to be disabled. This prevents concurrent writing to controller’s inputs from multiple sources.

Returns:

true is controller is in chained mode and false if it is not.

Protected Functions

virtual std::vector<hardware_interface::CommandInterface> on_export_reference_interfaces() = 0

Virtual method that each chainable controller should implement to export its chainable interfaces. Each chainable controller implements this methods where all input (command) interfaces are exported. The method has the same meaning as export_command_interface method from hardware_interface::SystemInterface or hardware_interface::ActuatorInterface.

Returns:

list of CommandInterfaces that other controller can use as their outputs.

virtual bool on_set_chained_mode(bool chained_mode)

Virtual method that each chainable controller should implement to switch chained mode.

Each chainable controller implements this methods to switch between “chained” and “external” mode. In “chained” mode all external interfaces like subscriber and service servers are disabled to avoid potential concurrency in input commands.

Parameters:

flag – [in] marking a switch to or from chained mode.

Returns:

true if controller successfully switched between “chained” and “external” mode. \default returns true so the method don’t have to be overridden if controller can always switch chained mode.

virtual return_type update_reference_from_subscribers(const rclcpp::Time &time, const rclcpp::Duration &period) = 0

Update reference from input topics when not in chained mode.

Each chainable controller implements this method to update reference from subscribers when not in chained mode.

Returns:

return_type::OK if update is successfully, otherwise return_type::ERROR.

virtual return_type update_and_write_commands(const rclcpp::Time &time, const rclcpp::Duration &period) = 0

Execute calculations of the controller and update command interfaces.

Update method for chainable controllers. In this method is valid to assume that \reference_interfaces_ hold the values for calculation of the commands in the current control step. This means that this method is called after \update_reference_from_subscribers if controller is not in chained mode.

Returns:

return_type::OK if calculation and writing of interface is successfully, otherwise return_type::ERROR.

Protected Attributes

std::vector<double> reference_interfaces_

Storage of values for reference interfaces.