text: /*
   * Copyright (C) 2012-2016 Open Source Robotics Foundation
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   *
  */
  #ifndef _GAZEBO_DIFFDRIVE_PLUGIN_HH_
  #define _GAZEBO_DIFFDRIVE_PLUGIN_HH_
  
  #include "gazebo/common/Plugin.hh"
  #include "gazebo/physics/physics.hh"
  #include "gazebo/transport/TransportTypes.hh"
  #include "gazebo/gazebo.hh"
  #include "gazebo/util/system.hh"
  
  namespace gazebo
  {
    class GAZEBO_VISIBLE DiffDrivePlugin : public ModelPlugin
    {
      public: DiffDrivePlugin();
      public: virtual void Load(physics::ModelPtr _model, sdf::ElementPtr _sdf);
      public: virtual void Init();
  
      private: void OnUpdate();
  
      private: void OnVelMsg(ConstPosePtr &_msg);
  
      private: transport::NodePtr node;
      private: transport::SubscriberPtr velSub;
  
      private: physics::ModelPtr model;
      private: physics::JointPtr leftJoint, rightJoint;
      private: event::ConnectionPtr updateConnection;
      private: double wheelSpeed[2];
      private: double wheelSeparation;
      private: double wheelRadius;
      private: common::Time prevUpdateTime;
  
      private: physics::LinkPtr link, leftWheelLink, rightWheelLink;
    };
  }
  #endif
  