Gazebo机器人仿真学习探索笔记(六)工具和实用程序.docx
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1、Gazebo机器人仿真学习探索笔 记(六)工具和实用程序Gazebo檄器人仿真擘曾探索肇IB (六)工具和实用程序Gazebo附带了许多工具和实用程序。这些教程说明了这些可用的工具,以及如何使用它们。主要有:1记录和播放2日志过滤3应用力/扭矩4 HDF5数据集官网介绍通俗具体,非常容易,请参考附件。附件-官方教程Logging and playbackOverviewThis tutorial explains how to use the Gazebo logging capabilities to record your simulation and then reproduce it
2、afterwards, using either the GUI or the command line.Gazebo log filesGazebo log files are compressed Jog files which contain an initial full description of the wholeworld, followed by a series of nworld states0.The initial description contains complete information about everything in the world, from
3、 the scene to the entities presentAfter that, every time something changes in simulation, a new world state is recorded. World states are much simpler, as they only contain information about what changed, such as:Simulation statistics such as the current simulation time and the number of physics ite
4、rations.Current state of each model in the scene, as well as the state of each link and joint in the model. This includes information such as instantaneous pose, velocity, acceleration and forces.Current pose of each light in the world.Tip: You can find the whole spec for the world state here.In thi
5、s tutorial we will record a few log files and then take a peek inside them at the end.Record a logLogging from the GUIStart your simulation. Here, as an example, we have a simple world with a double pendulum.Click on the logging icon on the top right, or hit Ctrl+D to bring up the Data Logger.You ca
6、n choose the directory where your log file will be saved by clicking the Browse button. Bydefault, log files Go to the -/.gazebo/log directory. In this example, we will save it in the -/logs/double_pendulum/ directory.Click on the red button to start recording. You should see the number of bytes in
7、your log file increasing on the right.Note: For efficiency, only models and lights which move over time are logged. If your scene is static, the number of bytes in your log file will not increase. This also means that the number of samples in your log file may be different from the number of iterati
8、ons in simulation.Click on the red button again to stop logging.Expand Recordings to see the path to the state.log file which was generated. It will be inside a time-stamped directory.Logging from the command lineFrom the command line, it is possible to log the whole simulation from the moment Gazeb
9、o starts running until it stops, or to trigger logging from an arbitary time.Logging the whole simulationAs an example, you can record the random_velocity.world as follows:gazebo -r -record_path -/logs/random_velocity worlds/random_velocity. worldYou can see a list of all of the available logging op
10、tions by running gazebo -help.-p play arg: Play a log file.-r -record : Record a log from the momentGazebo is opened until it is closed.-record_encoding arg: Compression encoding format for log data. The options are zlib (default), bz2 and txt.The log file will only be terminated when Gazebo is clos
11、ed. You can check the file was created by looking into the path given:$ Is -/logs/random_velocity/state.logLogging part of the simulationGazebo also provides the gz log tool, which can be used to trigger logging at any moment. While Gazebo is running, open another terminal and run the following to s
12、tart recording:gz log -d 1And to stop:gz log -d 0Check out gz log -help for other options.Play back a log fileOnce you have a log file, you can replay it visually or introspect it in several ways.Visualize in GUICurrently, it is not possible to open a log file from the GUI, so playback must be start
13、ed from the command line. Simply start Gazebo using the -p option to specify a log file, such as the one we recorded earlier:gazebo-u-p-/logs/double_pendulum/2016-01-25T15:09:49. 677400/gzserver/state.logTip: The -u option starts the log paused.Gazebo will open in playback mode. You can play, pause,
14、 rewind and step through the playback.Use Play / Pause to stop the playback.Use Rewind / Forward to skip to the beginning / end of the file.Use Step back / Step forward to skip samples. The number of samples skipped each time you press a step button can be changed in the box below. Samples might be
15、any number of iterations and seconds apart.Drag the current time marker and drop it to skip through the log.Input a current time on the right to skip to that sample.Command line toolsAs mentioned above, the gz log tool provides several options for introspecting your log file. Check out this tutorial
16、 for log filtering, for example.Here, lets quickly go over how you would take a look at the recorded states.Well use -s to step through a recorded file, like this:gzlog-s-f-/logs/double_pendulum/2016-01-25T15:09:49. 677400/gzserver/state.logYoull see the full initial SDF representation of the world,
17、 something like this:1.07.0.0-prel1062221443 38000000069 651000000! CDATA world name=,defaults(.)(.)(.)(.) 一 Press space to continue, Tq* to quit 一As you press space, you will step through the subsequent states. Youll note that the states are more compact and only contain information about what has
18、changed in the world. Heres an example of a state: ! CDATA43 38000000043 4784992281453763389 67787353043380 1.140-1.074-0.0000.000-0.0000.0001.000 1.000 1.0001.13998 -1.07367 -0.00000 0.000000.00000-0.00042-0.0000 0.0000 -0.0005 0.00040.00300.0001 1.38969 -1.79815 1.41059-2.453510.00000-0.000420.004
19、2 -0.2557 0.2659 1.96940.00480.0001 1.13999-1.073672.100002.33144-0.00000-0.000420.0063 -0.0008 -0.0005 -0.3739 0.00320.00010.000 0.000 0.0000.000 -0.000 0.000 1.000 1.0001.0000.00000 0.00000 0.00000 0.00000 -0.00000 0.00000 0.0000 0.0000 0.0000 0.0000 -0.00000.0000 Press space to continue, fqf to q
20、uit 一Note that there *s no information for the sun orthe ground_plane, since they are not moving.Log filteringIntroductionState logs are recordings of world state information from Gazebo. State includes pose, velocity, acceleration, and forces applied to all links of all models. Gazebo will only rec
21、ord state information for models that change over time. A state log file contains a header, the initial world description, and a time series of state.Gazebo Log Command line toolGazebo ships with a logging utility that is accessed via the gz log command.View the help information using:gz help log or
22、gz log -hExample UsageTip: Check out the tutorial on logging and playback for an overview of ways to record a log-Step 1: Create a state log fileStart by removing old log filesrm -rf -/.gazebo/log/*We will use the PR2 world to create a state log file.Start by running the Gazebo server with the -r co
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