ROS笔记-15 amcl with NetWorking ROS.txt

amcl with NetWorking ROS

	The	location of the robot, also known as its pose, is represented by a position	and orientation	in	the	map	coordinate frame (sometimes	also called	the	world coordinate frame)

	amcl maintains a set of	these poses, representing where	it	thinks the robot might be.	
		Each of	these candidate	poses has associated with it a probability;	higher-probability poses	are	more likely	to be where	the	robot actually is.	
		As the robot moves around the world, the sensor	readings are compared to the readings that would be	expected for each of the poses,	according to the map.	

	For	each candidate pose,	
		if the readings	are	consistent with	the	map, then the probability of that pose increases.	
		If the readings	are	inconsistent, then the probability decreases.	

	Over time, candidate poses with	very low probability	
		(i.e., where the robot is most likely not really in	that pose) go away, while those	with high probability stick	around

	1. PC端时间同步
		$ sudo ntpdate durant35.local

	2. Robot 启动
		$ source devel/setup.sh
		$ export ROS_HOSTNAME=durant35.local
		$ roscore &
		$ ./laserScannerConfig.sh
		// hector_slam
		//$ roslaunch hector_slam_launch hector_slam.launch
		
		$ roslaunch amcl_launch amcl.launch

http://ros-users.122217.n3.nabble.com/amcl-for-localization-td1168887.html			
	Is the robot moving?  
		The /amcl_pose data is published only on filter updates, which occur each time the robot has moved a sufficient distance.  
		The /tf data is published continuously; 
		this is where most programs look for the pose estimates produced by amcl.  To see it, try tf_echo: 
			rosrun tf tf_echo map odom
			rostopic echo /amcl_pose
		
	3. PC 启动
	source devel/setup.sh
	export ROS_HOSTNAME=durant35-aspire-tc.local
	export ROS_MASTER_URI=http://durant35.local:11311
	
	//roslaunch amcl_launch amcl.launch map:=lab314_2.yaml
	
	roslaunch amcl_launch amcl.launch map:=lab510_0518.yaml
	
	
	roslaunch amcl_launch amcl_networking.launch map:=lab510_0817.yaml
	amcl_networking
	设置 initial pose 并初始化 amcl 定位
	./CarControlServer
	roslaunch motor_driver_launch keyboard.launch



some problems 如何解决没有里程计下amcl运作的问题:

1. 《amcl does not need odometry data?》
	http://answers.ros.org/question/98221/amcl-does-not-need-odometry-data/

	amcl receives its odometry informations through the /odom -> /base_link transform. (Or whatever you have set as odom_frame_id and base_frame_id parameters)

	This means that you need a node (typically your hardware abstraction) that accumulates odom information from your base-robot and publish the aggregated pose as a transform.

	So no, laser only will not be sufficient.

2.《iRobot Create + Hokuyo LIDAR + YAML map + AMCL》
	http://answers.ros.org/question/61891/irobot-create-hokuyo-lidar-yaml-map-amcl/

	I guess you might need laser_scan_matcher to provide 'fake' odometry for amcl to work.


3.《how to: Building PCL & laser_scan_matcher on Raspberry pi 2》
	http://answers.ros.org/question/229788/how-to-building-pcl-laser_scan_matcher-on-raspberry-pi-2/


4.《AMCL + Laser Scan Matcher Crashing》
	http://answers.ros.org/question/98736/amcl-laser-scan-matcher-crashing/
	
	1. Remove the static transforms from map -> odom and odom -> base_link. You want them dynamic from amcl and the laser_scan_matcher and not static.

	2. fixed_frame for the laser_scan_matcher has to be set to /odom and not map, since the node is responsible for your odom -> base_link transform and not the localization within your map