[ControllerChaining] Export state interfaces from chainable controlle…

…rs (#1021)

---------

Co-authored-by: Bence Magyar <bence.magyar.robotics@gmail.com>
Co-authored-by: Dr. Denis <denis@stoglrobotics.de>
Co-authored-by: Christoph Fröhlich <christophfroehlich@users.noreply.github.com>

controller_interface/include/controller_interface/chainable_controller_interface.hpp

@@ -15,6 +15,7 @@
 #ifndef CONTROLLER_INTERFACE__CHAINABLE_CONTROLLER_INTERFACE_HPP_
 #define CONTROLLER_INTERFACE__CHAINABLE_CONTROLLER_INTERFACE_HPP_
 
+#include <string>
 #include <vector>
 
 #include "controller_interface/controller_interface_base.hpp"
@@ -55,6 +56,9 @@ class ChainableControllerInterface : public ControllerInterfaceBase
   CONTROLLER_INTERFACE_PUBLIC
   bool is_chainable() const final;
 
+  CONTROLLER_INTERFACE_PUBLIC
+  std::vector<hardware_interface::StateInterface> export_state_interfaces() final;
+
   CONTROLLER_INTERFACE_PUBLIC
   std::vector<hardware_interface::CommandInterface> export_reference_interfaces() final;
 
@@ -65,16 +69,27 @@ class ChainableControllerInterface : public ControllerInterfaceBase
   bool is_in_chained_mode() const final;
 
 protected:
-  /// Virtual method that each chainable controller should implement to export its chainable
-  /// interfaces.
+  /// Virtual method that each chainable controller should implement to export its read-only
+  /// chainable interfaces.
+  /**
+   * Each chainable controller implements this methods where all its state(read only) interfaces are
+   * exported. The method has the same meaning as `export_state_interfaces` method from
+   * hardware_interface::SystemInterface or hardware_interface::ActuatorInterface.
+   *
+   * \returns list of StateInterfaces that other controller can use as their inputs.
+   */
+  virtual std::vector<hardware_interface::StateInterface> on_export_state_interfaces();
+
+  /// Virtual method that each chainable controller should implement to export its read/write
+  /// 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 std::vector<hardware_interface::CommandInterface> on_export_reference_interfaces() = 0;
+  virtual std::vector<hardware_interface::CommandInterface> on_export_reference_interfaces();
 
   /// Virtual method that each chainable controller should implement to switch chained mode.
   /**
@@ -114,7 +129,12 @@ class ChainableControllerInterface : public ControllerInterfaceBase
   virtual return_type update_and_write_commands(
     const rclcpp::Time & time, const rclcpp::Duration & period) = 0;
 
+  /// Storage of values for state interfaces
+  std::vector<std::string> exported_state_interface_names_;
+  std::vector<double> state_interfaces_values_;
+
   /// Storage of values for reference interfaces
+  std::vector<std::string> exported_reference_interface_names_;
   std::vector<double> reference_interfaces_;
 
 private:

controller_interface/include/controller_interface/controller_interface.hpp

@@ -42,6 +42,14 @@ class ControllerInterface : public controller_interface::ControllerInterfaceBase
   CONTROLLER_INTERFACE_PUBLIC
   bool is_chainable() const final;
 
+  /**
+   * A non-chainable controller doesn't export any state interfaces.
+   *
+   * \returns empty list.
+   */
+  CONTROLLER_INTERFACE_PUBLIC
+  std::vector<hardware_interface::StateInterface> export_state_interfaces() final;
+
   /**
    * Controller has no reference interfaces.
    *

controller_interface/include/controller_interface/controller_interface_base.hpp

@@ -224,11 +224,20 @@ class ControllerInterfaceBase : public rclcpp_lifecycle::node_interfaces::Lifecy
   CONTROLLER_INTERFACE_PUBLIC
   virtual std::vector<hardware_interface::CommandInterface> export_reference_interfaces() = 0;
 
+  /**
+   * Export interfaces for a chainable controller that can be used as state interface by other
+   * controllers.
+   *
+   * \returns list of state interfaces for preceding controllers.
+   */
+  CONTROLLER_INTERFACE_PUBLIC
+  virtual std::vector<hardware_interface::StateInterface> export_state_interfaces() = 0;
+
   /**
    * 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.
+   * usually involves the usage of the controller's reference interfaces by the other
+   * controllers
    *
    * \returns true if mode is switched successfully and false if not.
    */

controller_interface/src/chainable_controller_interface.cpp

@@ -44,26 +44,35 @@ return_type ChainableControllerInterface::update(
   return ret;
 }
 
-std::vector<hardware_interface::CommandInterface>
-ChainableControllerInterface::export_reference_interfaces()
+std::vector<hardware_interface::StateInterface>
+ChainableControllerInterface::export_state_interfaces()
 {
-  auto reference_interfaces = on_export_reference_interfaces();
+  auto state_interfaces = on_export_state_interfaces();
 
-  // check if the "reference_interfaces_" variable is resized to number of interfaces
-  if (reference_interfaces_.size() != reference_interfaces.size())
+  // check if the names of the controller state interfaces begin with the controller's name
+  for (const auto & interface : state_interfaces)
   {
-    // TODO(destogl): Should here be "FATAL"? It is fatal in terms of controller but not for the
-    // framework
-    RCLCPP_FATAL(
-      get_node()->get_logger(),
-      "The internal storage for reference values 'reference_interfaces_' variable has size '%zu', "
-      "but it is expected to have the size '%zu' equal to the number of exported reference "
-      "interfaces. No reference interface will be exported. Please correct and recompile "
-      "the controller with name '%s' and try again.",
-      reference_interfaces_.size(), reference_interfaces.size(), get_node()->get_name());
-    reference_interfaces.clear();
+    if (interface.get_prefix_name() != get_node()->get_name())
+    {
+      RCLCPP_FATAL(
+        get_node()->get_logger(),
+        "The name of the interface '%s' does not begin with the controller's name. This is "
+        "mandatory for state interfaces. No state interface will be exported. Please "
+        "correct and recompile the controller with name '%s' and try again.",
+        interface.get_name().c_str(), get_node()->get_name());
+      state_interfaces.clear();
+      break;
+    }
   }
 
+  return state_interfaces;
+}
+
+std::vector<hardware_interface::CommandInterface>
+ChainableControllerInterface::export_reference_interfaces()
+{
+  auto reference_interfaces = on_export_reference_interfaces();
+
   // check if the names of the reference interfaces begin with the controller's name
   for (const auto & interface : reference_interfaces)
   {
@@ -113,4 +122,30 @@ bool ChainableControllerInterface::is_in_chained_mode() const { return in_chaine
 
 bool ChainableControllerInterface::on_set_chained_mode(bool /*chained_mode*/) { return true; }
 
+std::vector<hardware_interface::StateInterface>
+ChainableControllerInterface::on_export_state_interfaces()
+{
+  state_interfaces_values_.resize(exported_state_interface_names_.size(), 0.0);
+  std::vector<hardware_interface::StateInterface> state_interfaces;
+  for (size_t i = 0; i < exported_state_interface_names_.size(); ++i)
+  {
+    state_interfaces.emplace_back(hardware_interface::StateInterface(
+      get_node()->get_name(), exported_state_interface_names_[i], &state_interfaces_values_[i]));
+  }
+  return state_interfaces;
+}
+
+std::vector<hardware_interface::CommandInterface>
+ChainableControllerInterface::on_export_reference_interfaces()
+{
+  reference_interfaces_.resize(exported_reference_interface_names_.size(), 0.0);
+  std::vector<hardware_interface::CommandInterface> reference_interfaces;
+  for (size_t i = 0; i < exported_reference_interface_names_.size(); ++i)
+  {
+    reference_interfaces.emplace_back(hardware_interface::CommandInterface(
+      get_node()->get_name(), exported_reference_interface_names_[i], &reference_interfaces_[i]));
+  }
+  return reference_interfaces;
+}
+
 }  // namespace controller_interface

controller_interface/src/controller_interface.cpp

@@ -28,6 +28,11 @@ ControllerInterface::ControllerInterface() : ControllerInterfaceBase() {}
 
 bool ControllerInterface::is_chainable() const { return false; }
 
+std::vector<hardware_interface::StateInterface> ControllerInterface::export_state_interfaces()
+{
+  return {};
+}
+
 std::vector<hardware_interface::CommandInterface> ControllerInterface::export_reference_interfaces()
 {
   return {};

controller_interface/test/test_chainable_controller_interface.cpp

@@ -16,6 +16,9 @@
 
 #include <gmock/gmock.h>
 
+using ::testing::IsEmpty;
+using ::testing::SizeIs;
+
 TEST_F(ChainableControllerInterfaceTest, default_returns)
 {
   TestableChainableControllerInterface controller;
@@ -31,7 +34,7 @@ TEST_F(ChainableControllerInterfaceTest, default_returns)
   EXPECT_FALSE(controller.is_in_chained_mode());
 }
 
-TEST_F(ChainableControllerInterfaceTest, export_reference_interfaces)
+TEST_F(ChainableControllerInterfaceTest, export_state_interfaces)
 {
   TestableChainableControllerInterface controller;
 
@@ -42,16 +45,16 @@ TEST_F(ChainableControllerInterfaceTest, export_reference_interfaces)
     controller_interface::return_type::OK);
   ASSERT_NO_THROW(controller.get_node());
 
-  auto reference_interfaces = controller.export_reference_interfaces();
+  auto exported_state_interfaces = controller.export_state_interfaces();
 
-  ASSERT_EQ(reference_interfaces.size(), 1u);
-  EXPECT_EQ(reference_interfaces[0].get_prefix_name(), TEST_CONTROLLER_NAME);
-  EXPECT_EQ(reference_interfaces[0].get_interface_name(), "test_itf");
+  ASSERT_THAT(exported_state_interfaces, SizeIs(1));
+  EXPECT_EQ(exported_state_interfaces[0].get_prefix_name(), TEST_CONTROLLER_NAME);
+  EXPECT_EQ(exported_state_interfaces[0].get_interface_name(), "test_state");
 
-  EXPECT_EQ(reference_interfaces[0].get_value(), INTERFACE_VALUE);
+  EXPECT_EQ(exported_state_interfaces[0].get_value(), EXPORTED_STATE_INTERFACE_VALUE);
 }
 
-TEST_F(ChainableControllerInterfaceTest, reference_interfaces_storage_not_correct_size)
+TEST_F(ChainableControllerInterfaceTest, export_reference_interfaces)
 {
   TestableChainableControllerInterface controller;
 
@@ -62,13 +65,16 @@ TEST_F(ChainableControllerInterfaceTest, reference_interfaces_storage_not_correc
     controller_interface::return_type::OK);
   ASSERT_NO_THROW(controller.get_node());
 
-  // expect empty return because storage is not resized
-  controller.reference_interfaces_.clear();
   auto reference_interfaces = controller.export_reference_interfaces();
-  ASSERT_TRUE(reference_interfaces.empty());
+
+  ASSERT_THAT(reference_interfaces, SizeIs(1));
+  EXPECT_EQ(reference_interfaces[0].get_prefix_name(), TEST_CONTROLLER_NAME);
+  EXPECT_EQ(reference_interfaces[0].get_interface_name(), "test_itf");
+
+  EXPECT_EQ(reference_interfaces[0].get_value(), INTERFACE_VALUE);
 }
 
-TEST_F(ChainableControllerInterfaceTest, reference_interfaces_prefix_is_not_node_name)
+TEST_F(ChainableControllerInterfaceTest, interfaces_prefix_is_not_node_name)
 {
   TestableChainableControllerInterface controller;
 
@@ -83,7 +89,10 @@ TEST_F(ChainableControllerInterfaceTest, reference_interfaces_prefix_is_not_node
 
   // expect empty return because interface prefix is not equal to the node name
   auto reference_interfaces = controller.export_reference_interfaces();
-  ASSERT_TRUE(reference_interfaces.empty());
+  ASSERT_THAT(reference_interfaces, IsEmpty());
+  // expect empty return because interface prefix is not equal to the node name
+  auto exported_state_interfaces = controller.export_state_interfaces();
+  ASSERT_THAT(exported_state_interfaces, IsEmpty());
 }
 
 TEST_F(ChainableControllerInterfaceTest, setting_chained_mode)
@@ -98,12 +107,15 @@ TEST_F(ChainableControllerInterfaceTest, setting_chained_mode)
   ASSERT_NO_THROW(controller.get_node());
 
   auto reference_interfaces = controller.export_reference_interfaces();
-  ASSERT_EQ(reference_interfaces.size(), 1u);
+  ASSERT_THAT(reference_interfaces, SizeIs(1));
+  auto exported_state_interfaces = controller.export_state_interfaces();
+  ASSERT_THAT(exported_state_interfaces, SizeIs(1));
 
   EXPECT_FALSE(controller.is_in_chained_mode());
 
   // Fail setting chained mode
   EXPECT_EQ(reference_interfaces[0].get_value(), INTERFACE_VALUE);
+  EXPECT_EQ(exported_state_interfaces[0].get_value(), EXPORTED_STATE_INTERFACE_VALUE);
 
   EXPECT_FALSE(controller.set_chained_mode(true));
   EXPECT_FALSE(controller.is_in_chained_mode());
@@ -116,6 +128,7 @@ TEST_F(ChainableControllerInterfaceTest, setting_chained_mode)
 
   EXPECT_TRUE(controller.set_chained_mode(true));
   EXPECT_TRUE(controller.is_in_chained_mode());
+  EXPECT_EQ(exported_state_interfaces[0].get_value(), EXPORTED_STATE_INTERFACE_VALUE_IN_CHAINMODE);
 
   controller.configure();
   EXPECT_TRUE(controller.set_chained_mode(false));
@@ -147,27 +160,31 @@ TEST_F(ChainableControllerInterfaceTest, test_update_logic)
     controller_interface::return_type::OK);
   ASSERT_NO_THROW(controller.get_node());
 
+  EXPECT_FALSE(controller.set_chained_mode(false));
   EXPECT_FALSE(controller.is_in_chained_mode());
 
   // call update and update it from subscriber because not in chained mode
   ASSERT_EQ(
     controller.update(rclcpp::Time(0), rclcpp::Duration::from_seconds(0.01)),
     controller_interface::return_type::OK);
   ASSERT_EQ(controller.reference_interfaces_[0], INTERFACE_VALUE_INITIAL_REF - 1);
+  ASSERT_EQ(controller.state_interfaces_values_[0], EXPORTED_STATE_INTERFACE_VALUE + 1);
 
   // Provoke error in update from subscribers - return ERROR and update_and_write_commands not exec.
   controller.set_new_reference_interface_value(INTERFACE_VALUE_SUBSCRIBER_ERROR);
   ASSERT_EQ(
     controller.update(rclcpp::Time(0), rclcpp::Duration::from_seconds(0.01)),
     controller_interface::return_type::ERROR);
   ASSERT_EQ(controller.reference_interfaces_[0], INTERFACE_VALUE_INITIAL_REF - 1);
+  ASSERT_EQ(controller.state_interfaces_values_[0], EXPORTED_STATE_INTERFACE_VALUE + 1);
 
   // Provoke error from update - return ERROR, but reference interface is updated and not reduced
   controller.set_new_reference_interface_value(INTERFACE_VALUE_UPDATE_ERROR);
   ASSERT_EQ(
     controller.update(rclcpp::Time(0), rclcpp::Duration::from_seconds(0.01)),
     controller_interface::return_type::ERROR);
   ASSERT_EQ(controller.reference_interfaces_[0], INTERFACE_VALUE_UPDATE_ERROR);
+  ASSERT_EQ(controller.state_interfaces_values_[0], EXPORTED_STATE_INTERFACE_VALUE + 1);
 
   controller.reference_interfaces_[0] = 0.0;
 
@@ -181,6 +198,8 @@ TEST_F(ChainableControllerInterfaceTest, test_update_logic)
     controller.update(rclcpp::Time(0), rclcpp::Duration::from_seconds(0.01)),
     controller_interface::return_type::OK);
   ASSERT_EQ(controller.reference_interfaces_[0], -1.0);
+  ASSERT_EQ(
+    controller.state_interfaces_values_[0], EXPORTED_STATE_INTERFACE_VALUE_IN_CHAINMODE + 1);
 
   // Provoke error from update - return ERROR, but reference interface is updated directly
   controller.set_new_reference_interface_value(INTERFACE_VALUE_SUBSCRIBER_ERROR);
@@ -189,4 +208,6 @@ TEST_F(ChainableControllerInterfaceTest, test_update_logic)
     controller.update(rclcpp::Time(0), rclcpp::Duration::from_seconds(0.01)),
     controller_interface::return_type::ERROR);
   ASSERT_EQ(controller.reference_interfaces_[0], INTERFACE_VALUE_UPDATE_ERROR);
+  ASSERT_EQ(
+    controller.state_interfaces_values_[0], EXPORTED_STATE_INTERFACE_VALUE_IN_CHAINMODE + 1);
 }