RobotHWGroup with aliased interfaces

controller_interface/include/controller_interface/controller.h

@@ -111,7 +111,7 @@ class Controller: public ControllerBase
     {
       ROS_ERROR("This controller requires a hardware interface of type '%s'."
                 " Make sure this is registered in the hardware_interface::RobotHW class.",
-                getHardwareInterfaceType().c_str());
+                getHardwareInterfaceTypes().begin()->c_str());
       return false;
     }
 
@@ -130,9 +130,11 @@ class Controller: public ControllerBase
     return true;
   }
 
-  virtual std::string getHardwareInterfaceType() const
+  virtual std::set<std::string> getHardwareInterfaceTypes() const
   {
-    return hardware_interface::internal::demangledTypeName<T>();
+    std::set<std::string> ret_types;
+    ret_types.insert(hardware_interface::internal::demangledTypeName<T>());
+    return ret_types;
   }
 
 private:

controller_interface/include/controller_interface/controller_base.h

@@ -122,8 +122,24 @@ class ControllerBase
   /** \name Non Real-Time Safe Functions
    *\{*/
 
-  /// Get the name of this controller's hardware interface type
-  virtual std::string getHardwareInterfaceType() const = 0;
+  /// Get the names of the hardware interface types this controller uses
+  virtual std::set<std::string> getHardwareInterfaceTypes() const = 0;
+
+  /// Get the single name of the hardware interface this controller uses
+  virtual std::string getHardwareInterfaceType() 
+  {
+    std::set<std::string> types = getHardwareInterfaceTypes();
+
+    if(types.size() == 0) {
+      ROS_WARN("This controller has no interface type!");
+      return std::string("");
+    }
+
+    if(types.size() > 1)
+      ROS_WARN("This controller has more than one interface type!"
+                  "Use 'getHardwareInterfaceTypes' instead.");
+    return *(types.begin());
+  }
 
   /** \brief Request that the controller be initialized
    *