ros机器人之小乌龟仿真-路径记录
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通过自己不断地摸索,对ros系统有了一定的了解,首先装系统,这一过程中也遇到了很多问题,但通过不断地尝试,经过一天一夜的倒腾,总算是把系统给安装好了,接下来配置环境,虽然这个过程比较艰辛,总是出现编译出错或者没有功能包依赖等各种问题。但是通过我们的努力,都一点一点的解决了,我会再接再厉,
1.首先运行个小乌龟例程:
打开一个终端:roscore #运行ros环境
打开一个终端:rosrun turtlesim turtlesim_node #运行小乌龟仿真器节点,打开小乌龟运行场景
打开一个终端:rosrun turtlesim turtle_teleop_key #运行键盘控制节点,通过方向键控制小乌龟的运动
2.通过话题给小乌龟发送消息让小乌龟定向运动
命令如下
qqtsj ~ rostopic pub /turtle1/cmd_vel geometry_msgs/Twist "linear: x: 3.0 y: 0.0 z: 2.0 angular: x: 0.0 y: 0.0 z: 0.0" publishing and latching message. Press ctrl-C to terminate
可以定向的改变小乌龟的角速度和线速度以及小乌龟的转动角度,但是这样只能发送一次消息。
若需以一定的频率不断地发送消息数据,则为如下命令
qqtsj ~ rostopic pub -r 10 /turtle1/cmd_vel geometry_msgs/Twist "linear: x: 2.0 y: 0.0 z: 2.0 angular: x: 0.0 y: 0.0 z: 3.0"
其中-r为循环,10为发送给消息的频率(单位为hz),然后小乌龟就会根据规定的速度和角度定向的运动,这就用到了ROS系统中的话题通信,以便后面研究机器人打下基础。
查看消息的结构:rosmsg show geometry/Twlist
服务:service
查看服务的列表(服务的内容):rosservice list
qqtsj ~ rosservice list /clear /kill /reset /rosout/get_loggers /rosout/set_logger_level /rostopic_26871_1579011097016/get_loggers /rostopic_26871_1579011097016/set_logger_level /spawn /teleop_turtle/get_loggers /teleop_turtle/set_logger_level /turtle1/set_pen /turtle1/teleport_absolute /turtle1/teleport_relative /turtlesim/get_loggers /turtlesim/set_logger_level
建立一个新的海龟:rosservice call /spawn (Tab键两下)
qqtsj ~ rosservice call /spawn "x: 0.0 y: 0.0 theta: 0.0 name: 'turtle2'" name: "turtle2"
路径记录
首先创建一个bag包,存放小乌龟运行的路径,记录下小乌龟的行进路线。命令为
qqtsj ~ rosbag record -a -O cmd_record [ INFO] [1579021261.961366553]: Recording to cmd_record.bag. [ INFO] [1579021261.962496904]: Subscribing to /turtle1/color_sensor [ INFO] [1579021261.964809471]: Subscribing to /turtle2/color_sensor [ INFO] [1579021261.966782329]: Subscribing to /rosout [ INFO] [1579021261.968599482]: Subscribing to /turtle2/pose [ INFO] [1579021261.970367259]: Subscribing to /rosout_agg [ INFO] [1579021261.972389384]: Subscribing to /turtle1/cmd_vel [ INFO] [1579021261.975169187]: Subscribing to /turtle1/pose
路径重现
在bag包中已经记录了小乌龟的路径,然后通过调用bag包去实现小乌龟路径的重现,小乌龟会按照记录的路径重新运动,如下
qqtsj ~ rosbag play cmd_record.bag [ INFO] [1579021485.400287473]: Opening cmd_record.bag Waiting 0.2 seconds after advertising topics... done. Hit space to toggle paused, or 's' to step. [RUNNING] Bag Time: 1579021261.977381 Duration: 0.000000 / [RUNNING] Bag Time: 1579021261.978402 Duration: 0.001021 / [RUNNING] Bag Time: 1579021262.078691 Duration: 0.101311 / [RUNNING] Bag Time: 1579021262.177369 Duration: 0.199988 / [RUNNING] Bag Time: 1579021262.185319 Duration: 0.207938 / [RUNNING] Bag Time: 1579021262.201285 Duration: 0.223904 / [RUNNING] Bag Time: 1579021262.217652 Duration: 0.240271 / [RUNNING] Bag Time: 1579021262.233162 Duration: 0.255782 / [RUNNING] Bag Time: 1579021262.249374 Duration: 0.271993 / [RUNNING] Bag Time: 1579021262.266055 Duration: 0.288674 / [RUNNING] Bag Time: 1579021262.281470 Duration: 0.304090 /
通过对小乌龟的控制,定向移动,路径记录,路径重现。对接下来ros机器人的研究有一定的帮助,会加深我们对机器人的理解。