1. 在我的程序里,从Service的客户端(比如网页端)选择一个目标点后,服务端获得目标的位姿,传递给需要的线程.

1. 初始化一个Action的客户端SimpleActionClient的指针g_ac_ptr:

actionlib::SimpleActionClient<move_base_msgs::MoveBaseAction>* g_ac_ptr=NULL;
// 初始化move_base ActionClient
actionlib::SimpleActionClient<move_base_msgs::MoveBaseAction> ac("move_base",true);     // action名称为move_base
g_ac_ptr = &ac;

1. 发送目标:

move_base_msgs::MoveBaseGoal goal;

goal.target_pose.header.frame_id = "map";
goal.target_pose.header.stamp = ros::Time::now();
goal.target_pose.pose = g_request.pose;    // 服务端获得目标的位姿

g_ac_ptr->sendGoal(goal);

sendGoal会将目标点发送到move_base节点进行处理,进而会发布话题move_base/goal,消息类型为move_base_msgs/MoveBaseActionGoal,用于存储导航的目标位置数据

我没有用到/move_base_simple/goal话题,其实平时应该用这个,比如:

rostopic pub /move_base_simple/goal geometry_msgs/PoseStamped \
'{ header: { frame_id: "base_link" }, pose: { position: { x: 1.0, y: 0, z: 0 }, orientation: { x: 0, y: 0, z: 0, w: 1 } } }'

1. Action的服务端在MoveBase的构造函数:

// 回调函数是 MoveBase::executeCb
as_ = new MoveBaseActionServer(ros::NodeHandle(), "move_base", boost::bind(&MoveBase::executeCb, this, _1), false);
    ......
//we're all set up now so we can start the action server
as_->start();

MoveBase::executeCb函数在move_base693行,过程太复杂,步骤大致如下:

• 验证目标位姿的欧拉角是否合理
• 目标位姿转换为全局frame中的位姿

//we have a goal so start the planner
boost::unique_lock<boost::recursive_mutex> lock(planner_mutex_);
planner_goal_ = goal;
runPlanner_ = true;
planner_cond_.notify_one();
lock.unlock();

• 发布话题move_base/current_goal,与/move_base/goal的target_pose部分只有seq的不同

调用executeCycle
进行local plan,发布cmd_vel的topic，根据小车处于的状态，进行相应的实现(会进行plan,control,clear obstacle)

enum MoveBaseState {
  PLANNING,
  CONTROLLING,
  CLEARING
};

enum RecoveryTrigger
{
  PLANNING_R,
  CONTROLLING_R,
  OSCILLATION_R
};

---

DWAPlannerROS和TrajectoryPlannerROS都继承了 nav_core::BaseLocalPlanner

DWAPlannerROS::computeVelocityCommands
    dwaComputeVelocityCommands(current_pose_, cmd_vel);

DWAPlannerROS::publishGlobalPlan

base_local_planner::publishPlan(path, g_plan_pub_);

MoveBase::executeCycle调用了DWAPlannerROS::computeVelocityCommands