[Feature] Fallback controllers

controller_manager/CMakeLists.txt

@@ -91,6 +91,7 @@ if(BUILD_TESTING)
   target_link_libraries(test_controller_manager
     controller_manager
     test_controller
+    test_chainable_controller
     ros2_control_test_assets::ros2_control_test_assets
   )
 

controller_manager/doc/userdoc.rst

@@ -87,6 +87,18 @@ update_rate (mandatory; integer)
   Name of a plugin exported using ``pluginlib`` for a controller.
   This is a class from which controller's instance with name "``controller_name``" is created.
 
+<controller_name>.params_file
+  The absolute path to the YAML file with parameters for the controller.
+  The file should contain the parameters for the controller in the standard ROS 2 YAML format.
+
+<controller_name>.fallback_controllers
+  List of controllers that are activated as a fallback strategy, when the spawned controllers fail by returning ``return_type::ERROR`` during the ``update`` cycle.
+  It is recommended to add all the controllers needed for the fallback strategy to the list, including the chainable controllers whose interfaces are used by the main fallback controllers.
+
+.. warning::
+  The fallback controllers activation is subject to the availability of the state and command interfaces at the time of activation.
+  It is recommended to test the fallback strategy in simulation before deploying it on the real robot.
+
 Handling Multiple Controller Managers
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 

controller_manager/include/controller_manager/controller_manager.hpp

@@ -128,6 +128,12 @@ class ControllerManager : public rclcpp::Node
     return add_controller_impl(controller_spec);
   }
 
+  controller_interface::ControllerInterfaceBaseSharedPtr add_controller(
+    const ControllerSpec & controller_spec)
+  {
+    return add_controller_impl(controller_spec);
+  }
+
   /// configure_controller Configure controller by name calling their "configure" method.
   /**
    * \param[in] controller_name as a string.
@@ -418,6 +424,18 @@ class ControllerManager : public rclcpp::Node
     const std::vector<ControllerSpec> & controllers, int strictness,
     const ControllersListIterator controller_it);
 
+  /// The methood to check if the fallback controllers of the given controllers are in the right
+  /// state, so they can be activated immediately
+  /**
+   * \param[in] controllers is a list of controllers to activate.
+   * \param[in] controller_it is the iterator pointing to the controller to be activated.
+   * \return return_type::OK if all fallback controllers are in the right state, otherwise
+   * return_type::ERROR.
+   */
+  CONTROLLER_MANAGER_PUBLIC
+  controller_interface::return_type check_fallback_controllers_state_pre_activation(
+    const std::vector<ControllerSpec> & controllers, const ControllersListIterator controller_it);
+
   /**
    * @brief Inserts a controller into an ordered list based on dependencies to compute the
    * controller chain.

controller_manager/src/controller_manager.cpp

@@ -170,6 +170,41 @@ void controller_chain_spec_cleanup(
   }
   ctrl_chain_spec.erase(controller);
 }
+
+// Gets the list of active controllers that use the command interface of the given controller
+void get_active_controllers_using_command_interfaces_of_controller(
+  const std::string & controller_name,
+  const std::vector<controller_manager::ControllerSpec> & controllers,
+  std::vector<std::string> & controllers_using_command_interfaces)
+{
+  auto it = std::find_if(
+    controllers.begin(), controllers.end(),
+    std::bind(controller_name_compare, std::placeholders::_1, controller_name));
+  if (it == controllers.end())
+  {
+    RCLCPP_ERROR(
+      rclcpp::get_logger("ControllerManager::utils"),
+      "Controller '%s' not found in the list of controllers.", controller_name.c_str());
+    return;
+  }
+  const auto cmd_itfs = it->c->command_interface_configuration().names;
+  for (const auto & cmd_itf : cmd_itfs)
+  {
+    for (const auto & controller : controllers)
+    {
+      const auto ctrl_cmd_itfs = controller.c->command_interface_configuration().names;
+      // check if the controller is active and has the command interface and make sure that it
+      // doesn't exist in the list already
+      if (
+        is_controller_active(controller.c) &&
+        std::find(ctrl_cmd_itfs.begin(), ctrl_cmd_itfs.end(), cmd_itf) != ctrl_cmd_itfs.end())
+      {
+        add_element_to_list(controllers_using_command_interfaces, controller.info.name);
+      }
+    }
+  }
+}
+
 }  // namespace
 
 namespace controller_manager
@@ -536,6 +571,15 @@ controller_interface::ControllerInterfaceBaseSharedPtr ControllerManager::load_c
   }
   if (get_parameter(fallback_ctrl_param, fallback_controllers) && !fallback_controllers.empty())
   {
+    if (
+      std::find(fallback_controllers.begin(), fallback_controllers.end(), controller_name) !=
+      fallback_controllers.end())
+    {
+      RCLCPP_ERROR(
+        get_logger(), "Controller '%s' cannot be a fallback controller for itself.",
+        controller_name.c_str());
+      return nullptr;
+    }
     controller_spec.info.fallback_controllers_names = fallback_controllers;
   }
 
@@ -1082,6 +1126,11 @@ controller_interface::return_type ControllerManager::switch_controller(
       status = check_following_controllers_for_activate(controllers, strictness, controller_it);
     }
 
+    if (status == controller_interface::return_type::OK)
+    {
+      status = check_fallback_controllers_state_pre_activation(controllers, controller_it);
+    }
+
     if (status != controller_interface::return_type::OK)
     {
       RCLCPP_WARN(
@@ -2360,16 +2409,67 @@ controller_interface::return_type ControllerManager::update(
   }
   if (!failed_controllers_list.empty())
   {
-    std::string failed_controllers;
+    std::vector<std::string> active_controllers_using_interfaces(failed_controllers_list);
+    active_controllers_using_interfaces.reserve(500);
+    std::vector<std::string> cumulative_fallback_controllers;
+    cumulative_fallback_controllers.reserve(500);
+
+    for (const auto & failed_ctrl : failed_controllers_list)
+    {
+      auto ctrl_it = std::find_if(
+        rt_controller_list.begin(), rt_controller_list.end(),
+        std::bind(controller_name_compare, std::placeholders::_1, failed_ctrl));
+      if (ctrl_it != rt_controller_list.end())
+      {
+        for (const auto & fallback_controller : ctrl_it->info.fallback_controllers_names)
+        {
+          cumulative_fallback_controllers.push_back(fallback_controller);
+          get_active_controllers_using_command_interfaces_of_controller(
+            fallback_controller, rt_controller_list, active_controllers_using_interfaces);
+        }
+      }
+    }
+    std::string controllers_string;
+    controllers_string.reserve(500);
     for (const auto & controller : failed_controllers_list)
     {
-      failed_controllers += "\n\t- " + controller;
+      controllers_string.append(controller);
+      controllers_string.append(" ");
     }
     RCLCPP_ERROR(
-      get_logger(), "Deactivating following controllers as their update resulted in an error :%s",
-      failed_controllers.c_str());
-
-    deactivate_controllers(rt_controller_list, failed_controllers_list);
+      get_logger(), "Deactivating controllers : [ %s] as their update resulted in an error!",
+      controllers_string.c_str());
+    if (active_controllers_using_interfaces.size() > failed_controllers_list.size())
+    {
+      controllers_string.clear();
+      for (size_t i = failed_controllers_list.size();
+           i < active_controllers_using_interfaces.size(); i++)
+      {
+        controllers_string.append(active_controllers_using_interfaces[i]);
+        controllers_string.append(" ");
+      }
+      RCLCPP_ERROR_EXPRESSION(
+        get_logger(), !controllers_string.empty(),
+        "Deactivating controllers : [ %s] using the command interfaces needed for the fallback "
+        "controllers to activate.",
+        controllers_string.c_str());
+    }
+    if (!cumulative_fallback_controllers.empty())
+    {
+      controllers_string.clear();
+      for (const auto & controller : cumulative_fallback_controllers)
+      {
+        controllers_string.append(controller);
+        controllers_string.append(" ");
+      }
+      RCLCPP_ERROR(
+        get_logger(), "Activating fallback controllers : [ %s]", controllers_string.c_str());
+    }
+    deactivate_controllers(rt_controller_list, active_controllers_using_interfaces);
+    if (!cumulative_fallback_controllers.empty())
+    {
+      activate_controllers(rt_controller_list, cumulative_fallback_controllers);
+    }
   }
 
   // there are controllers to (de)activate
@@ -2765,6 +2865,162 @@ controller_interface::return_type ControllerManager::check_preceeding_controller
   return controller_interface::return_type::OK;
 }
 
+controller_interface::return_type
+ControllerManager::check_fallback_controllers_state_pre_activation(
+  const std::vector<ControllerSpec> & controllers, const ControllersListIterator controller_it)
+{
+  for (const auto & fb_ctrl : controller_it->info.fallback_controllers_names)
+  {
+    auto fb_ctrl_it = std::find_if(
+      controllers.begin(), controllers.end(),
+      std::bind(controller_name_compare, std::placeholders::_1, fb_ctrl));
+    if (fb_ctrl_it == controllers.end())
+    {
+      RCLCPP_ERROR(
+        get_logger(),
+        "Unable to find the fallback controller : '%s' of the controller : '%s' "
+        "within the controller list",
+        fb_ctrl.c_str(), controller_it->info.name.c_str());
+      return controller_interface::return_type::ERROR;
+    }
+    else
+    {
+      if (!(is_controller_inactive(fb_ctrl_it->c) || is_controller_active(fb_ctrl_it->c)))
+      {
+        RCLCPP_ERROR(
+          get_logger(),
+          "Controller with name '%s' cannot be activated, as it's fallback controller : '%s'"
+          " need to be configured and be in inactive/active state!",
+          controller_it->info.name.c_str(), fb_ctrl.c_str());
+        return controller_interface::return_type::ERROR;
+      }
+      for (const auto & fb_cmd_itf : fb_ctrl_it->c->command_interface_configuration().names)
+      {
+        if (!resource_manager_->command_interface_is_available(fb_cmd_itf))
+        {
+          ControllersListIterator following_ctrl_it;
+          if (is_interface_a_chained_interface(fb_cmd_itf, controllers, following_ctrl_it))
+          {
+            // if following_ctrl_it is inactive and it is in the fallback list of the
+            // controller_it and then check it it's exported reference interface names list if
+            // it's available
+            if (is_controller_inactive(following_ctrl_it->c))
+            {
+              if (
+                std::find(
+                  controller_it->info.fallback_controllers_names.begin(),
+                  controller_it->info.fallback_controllers_names.end(),
+                  following_ctrl_it->info.name) !=
+                controller_it->info.fallback_controllers_names.end())
+              {
+                const auto exported_ref_itfs =
+                  resource_manager_->get_controller_reference_interface_names(
+                    following_ctrl_it->info.name);
+                if (
+                  std::find(exported_ref_itfs.begin(), exported_ref_itfs.end(), fb_cmd_itf) ==
+                  exported_ref_itfs.end())
+                {
+                  RCLCPP_ERROR(
+                    get_logger(),
+                    "Controller with name '%s' cannot be activated, as the command interface : "
+                    "'%s' required by its fallback controller : '%s' is not exported by the "
+                    "controller : '%s' in the current fallback list!",
+                    controller_it->info.name.c_str(), fb_cmd_itf.c_str(), fb_ctrl.c_str(),
+                    following_ctrl_it->info.name.c_str());
+                  return controller_interface::return_type::ERROR;
+                }
+              }
+              else
+              {
+                RCLCPP_ERROR(
+                  get_logger(),
+                  "Controller with name '%s' cannot be activated, as the command interface : "
+                  "'%s' required by its fallback controller : '%s' is not available as the "
+                  "controller is not in active state!. May be consider adding this controller to "
+                  "the fallback list of the controller : '%s' or already have it activated.",
+                  controller_it->info.name.c_str(), fb_cmd_itf.c_str(), fb_ctrl.c_str(),
+                  following_ctrl_it->info.name.c_str());
+                return controller_interface::return_type::ERROR;
+              }
+            }
+          }
+          else
+          {
+            RCLCPP_ERROR(
+              get_logger(),
+              "Controller with name '%s' cannot be activated, as not all of its fallback "
+              "controller's : '%s' command interfaces are currently available!",
+              controller_it->info.name.c_str(), fb_ctrl.c_str());
+            return controller_interface::return_type::ERROR;
+          }
+        }
+      }
+      for (const auto & fb_state_itf : fb_ctrl_it->c->state_interface_configuration().names)
+      {
+        if (!resource_manager_->state_interface_is_available(fb_state_itf))
+        {
+          ControllersListIterator following_ctrl_it;
+          if (is_interface_a_chained_interface(fb_state_itf, controllers, following_ctrl_it))
+          {
+            // if following_ctrl_it is inactive and it is in the fallback list of the
+            // controller_it and then check it it's exported reference interface names list if
+            // it's available
+            if (is_controller_inactive(following_ctrl_it->c))
+            {
+              if (
+                std::find(
+                  controller_it->info.fallback_controllers_names.begin(),
+                  controller_it->info.fallback_controllers_names.end(),
+                  following_ctrl_it->info.name) !=
+                controller_it->info.fallback_controllers_names.end())
+              {
+                const auto exported_state_itfs =
+                  resource_manager_->get_controller_exported_state_interface_names(
+                    following_ctrl_it->info.name);
+                if (
+                  std::find(exported_state_itfs.begin(), exported_state_itfs.end(), fb_state_itf) ==
+                  exported_state_itfs.end())
+                {
+                  RCLCPP_ERROR(
+                    get_logger(),
+                    "Controller with name '%s' cannot be activated, as the state interface : "
+                    "'%s' required by its fallback controller : '%s' is not exported by the "
+                    "controller : '%s' in the current fallback list!",
+                    controller_it->info.name.c_str(), fb_state_itf.c_str(), fb_ctrl.c_str(),
+                    following_ctrl_it->info.name.c_str());
+                  return controller_interface::return_type::ERROR;
+                }
+              }
+              else
+              {
+                RCLCPP_ERROR(
+                  get_logger(),
+                  "Controller with name '%s' cannot be activated, as the state interface : "
+                  "'%s' required by its fallback controller : '%s' is not available as the "
+                  "controller is not in active state!. May be consider adding this controller to "
+                  "the fallback list of the controller : '%s' or already have it activated.",
+                  controller_it->info.name.c_str(), fb_state_itf.c_str(), fb_ctrl.c_str(),
+                  following_ctrl_it->info.name.c_str());
+                return controller_interface::return_type::ERROR;
+              }
+            }
+          }
+          else
+          {
+            RCLCPP_ERROR(
+              get_logger(),
+              "Controller with name '%s' cannot be activated, as not all of its fallback "
+              "controller's : '%s' state interfaces are currently available!",
+              controller_it->info.name.c_str(), fb_ctrl.c_str());
+            return controller_interface::return_type::ERROR;
+          }
+        }
+      }
+    }
+  }
+  return controller_interface::return_type::OK;
+}
+
 void ControllerManager::controller_activity_diagnostic_callback(
   diagnostic_updater::DiagnosticStatusWrapper & stat)
 {

controller_manager/test/test_controller/test_controller.cpp

@@ -137,6 +137,11 @@ std::vector<double> TestController::get_state_interface_data() const
   return state_intr_data;
 }
 
+void TestController::set_external_commands_for_testing(const std::vector<double> & commands)
+{
+  external_commands_for_testing_ = commands;
+}
+
 }  // namespace test_controller
 
 #include "pluginlib/class_list_macros.hpp"

controller_manager/test/test_controller/test_controller.hpp

@@ -70,6 +70,8 @@ class TestController : public controller_interface::ControllerInterface
 
   const std::string & getRobotDescription() const;
 
+  void set_external_commands_for_testing(const std::vector<double> & commands);
+
   unsigned int internal_counter = 0;
   bool simulate_cleanup_failure = false;
   // Variable where we store when cleanup was called, pointer because the controller