1 00:00:00,930 --> 00:00:05,550 In this lecture, we are going to take a break from coding and go over Ross bag files. 2 00:00:05,760 --> 00:00:10,860 Bag files are used to record data coming in over Ross so that you can play it back at a later time. 3 00:00:11,010 --> 00:00:15,960 Bank files are incredibly useful when it comes to robots, which are difficult to deploy and test, 4 00:00:15,960 --> 00:00:20,730 as well as review how your developed robot code responded to certain situations. 5 00:00:21,090 --> 00:00:26,310 We're going to first go ahead and create our own bank file and then the resources section. 6 00:00:26,310 --> 00:00:31,920 I will also have available a bank file from an autonomous surface vehicle I worked on a while back so 7 00:00:31,920 --> 00:00:36,000 you can see data from a real robot play back as it did when we deployed it. 8 00:00:37,510 --> 00:00:39,400 So far back file we are going to create. 9 00:00:39,400 --> 00:00:44,590 We're just going to record information from the nodes we created in the previous sections project where 10 00:00:44,590 --> 00:00:50,500 we created in RPM and Speed Publisher Node, which had values we could change via parameters. 11 00:00:50,800 --> 00:00:52,270 So I can go ahead and open up. 12 00:00:52,270 --> 00:00:54,490 VISCO just to remind you of what this looked like. 13 00:00:56,100 --> 00:01:01,650 So in this launch file, I ran two different nodes our RPM, pub node and our speed pub node, and we 14 00:01:01,650 --> 00:01:05,010 can change parameters such as the wheel radius. 15 00:01:05,370 --> 00:01:12,600 So I'll go ahead and open up a terminal, change into my workspace directory, source it and launch 16 00:01:12,600 --> 00:01:13,380 the project. 17 00:01:16,800 --> 00:01:22,890 Now I'm going to open a new terminal tab and double check that our code is running properly by listing 18 00:01:22,890 --> 00:01:29,040 our topics and we can see them there and we can check that it's publishing using the RAS two topic Echo 19 00:01:29,040 --> 00:01:29,460 Command. 20 00:01:32,810 --> 00:01:35,900 All right, So our publishers are running, so let's open a new terminal. 21 00:01:36,740 --> 00:01:38,930 Where we will record our bank file. 22 00:01:40,010 --> 00:01:43,790 To record the bank file, we're going to use the Ross to bag record command. 23 00:01:44,060 --> 00:01:50,090 You can see what type of options we have with the ROS commands on the corresponding ROS index page. 24 00:01:50,420 --> 00:01:56,060 We'll discuss packages and the ROS index page in the upcoming lecture, but for now we're just going 25 00:01:56,060 --> 00:01:59,540 to quickly go through some of these Ros to bag commands. 26 00:01:59,570 --> 00:02:04,180 For now, I'm going to use the dash a flag to record all topics. 27 00:02:04,190 --> 00:02:08,200 If we only wanted to record certain topics we would type them out instead. 28 00:02:08,210 --> 00:02:12,440 So for example, slash speed or slash RPM. 29 00:02:13,190 --> 00:02:15,970 But again, for now I'm just going to use the dash a flag. 30 00:02:15,980 --> 00:02:22,970 Then I'm going to use the dash o flag to specify the output name, which in this case I'll set to test 31 00:02:22,970 --> 00:02:29,330 dot bag because if not, the default name will be the current date and time stamp. 32 00:02:29,690 --> 00:02:33,050 Note that it will save the bag in our current terminal directory. 33 00:02:33,050 --> 00:02:37,790 So in this case I'm actually within our ROS to py workspace directory. 34 00:02:37,970 --> 00:02:44,150 I'm actually going to quickly go ahead and change into our home directory and I'm going to go ahead 35 00:02:44,150 --> 00:02:45,470 and hit enter. 36 00:02:46,320 --> 00:02:50,430 So you'll see it begin subscribing to all of the different topics. 37 00:02:50,430 --> 00:02:54,860 Let's create some variety in our bag file by changing our wheel size parameter. 38 00:02:54,870 --> 00:02:58,530 So I'm going to go open up a another terminal tab. 39 00:03:00,030 --> 00:03:03,540 And run Ra Super am set to change our wheel radius side. 40 00:03:08,790 --> 00:03:11,870 Oh, and make sure to set it to a double instead of an integer. 41 00:03:12,260 --> 00:03:17,660 So we set the parameter successfully and we see that it's gone ahead and changed here in our file, 42 00:03:17,660 --> 00:03:21,440 and we could go ahead and change that one more time just to add some more variety. 43 00:03:22,590 --> 00:03:24,270 And we see it change again. 44 00:03:24,270 --> 00:03:27,390 So I'm going to go ahead and stop this bag file by hitting control C. 45 00:03:28,410 --> 00:03:34,860 And we can go ahead and stop these other terminals from running the launch file and echoing the topic 46 00:03:34,860 --> 00:03:35,730 information. 47 00:03:35,760 --> 00:03:37,350 So let's go ahead and clear this up. 48 00:03:37,350 --> 00:03:39,390 So go ahead and clear the screens. 49 00:03:43,230 --> 00:03:45,740 And I'll go ahead and close these first two terminals. 50 00:03:46,070 --> 00:03:48,140 So now if we go into our home directory. 51 00:03:48,830 --> 00:03:56,330 We can see this test bag folder and if we open it up, it has two files in it metadata, a L and a DB 52 00:03:56,330 --> 00:04:00,050 three file, which is an SQLite version of what a saving are. 53 00:04:00,050 --> 00:04:01,280 Ros data. 54 00:04:02,150 --> 00:04:08,510 So to find more information about what's in this bag, we can use the Ross to bag info command on that 55 00:04:08,510 --> 00:04:09,200 bag file. 56 00:04:10,930 --> 00:04:14,210 And here we can see things such as the bag size. 57 00:04:14,230 --> 00:04:16,780 We can see the storage type is sky three. 58 00:04:16,780 --> 00:04:18,730 The duration of the bag file. 59 00:04:18,730 --> 00:04:25,270 When we took the bag file as well as the number of messages, topic information and a little bit of 60 00:04:25,270 --> 00:04:27,880 information into each individual topic. 61 00:04:27,880 --> 00:04:33,340 So in this case we see we got information from ROS out RPM and the speed topics. 62 00:04:33,460 --> 00:04:35,590 So keep in mind I stopped at my speed publisher. 63 00:04:35,590 --> 00:04:42,190 So if I do ROS two topic list, we don't see that speed in RPM topic being published to. 64 00:04:42,640 --> 00:04:46,120 Let's go ahead and play this bag file back to get the information from it. 65 00:04:46,120 --> 00:04:52,150 So go ahead and clear the screen and do Ros to bag play and I will do dash L which will loop the bag 66 00:04:52,150 --> 00:04:53,050 file once it finishes. 67 00:04:53,050 --> 00:04:56,140 It'll go back to the beginning and I do test dot bag. 68 00:04:57,470 --> 00:05:00,110 So we can see that our ROS bag is playing. 69 00:05:00,110 --> 00:05:09,110 And now if I do Ross to topic list again, we see that now we have our RPM and speed topics that are 70 00:05:09,110 --> 00:05:12,200 coming from the bag file and we can actually go ahead and echo them. 71 00:05:16,930 --> 00:05:23,050 So here we see the initial value that was coming from our speed publisher, and eventually we should 72 00:05:23,050 --> 00:05:29,170 see the values change because we changed the parameters midway through recording this back file. 73 00:05:29,650 --> 00:05:35,380 So here we see it changes to 5.23, and then we should see it change again to. 74 00:05:36,260 --> 00:05:37,650 10.47. 75 00:05:37,670 --> 00:05:37,940 All right. 76 00:05:37,940 --> 00:05:39,170 So go ahead and stop these. 77 00:05:41,430 --> 00:05:46,500 Now, I know this isn't the coolest bag file ever, so I prepared a bag file with data from an autonomous 78 00:05:46,500 --> 00:05:50,730 surface vehicle I worked with a while back, which I have in my downloads folder. 79 00:05:50,730 --> 00:05:51,930 So go ahead and clear the screen. 80 00:05:55,540 --> 00:05:58,270 And again, you can just grab this from the resources folder. 81 00:05:58,630 --> 00:06:02,410 So I have it here in my downloads folder, this marine surface vehicle bag, I've already gone ahead 82 00:06:02,410 --> 00:06:05,230 and unzipped it, so if I go into my downloads folder. 83 00:06:07,460 --> 00:06:08,450 We can see it there. 84 00:06:08,450 --> 00:06:14,150 And again, I'm not playing anything in the background, so if I do Ross to topic list, we only get 85 00:06:14,150 --> 00:06:15,200 our basic topics out. 86 00:06:15,200 --> 00:06:22,820 But if I do Ross to bag Play, Dash L and the name of the bag file, we can see it playing. 87 00:06:22,820 --> 00:06:28,670 And now if I run Ross to topic list again, we see several different topics such as Things for the Fix, 88 00:06:28,670 --> 00:06:35,300 which is the GPS of the robot, the IMU information, as well as the velocity and camera information 89 00:06:35,300 --> 00:06:38,240 that was coming from this particular robotic system. 90 00:06:38,390 --> 00:06:45,020 And of course, we can always go ahead and check this out by doing a Ross two topic echo slash fix. 91 00:06:47,750 --> 00:06:51,680 Here we can see latitude and longitude coordinates of this particular robot. 92 00:06:51,680 --> 00:06:53,000 So as a little side challenge. 93 00:06:53,030 --> 00:06:57,030 See if you can figure out where this robot was when this bag file was being taken. 94 00:06:57,050 --> 00:06:59,150 So go ahead and stop this with control C. 95 00:07:02,550 --> 00:07:06,660 And now notice we have camera information, but we can't just really echo that, right? 96 00:07:06,660 --> 00:07:12,930 If I do, Ross, too, topic Echo and I do this when the front camera, USB camera. 97 00:07:14,820 --> 00:07:17,880 We had a series of numbers just being printed to this screen endlessly. 98 00:07:17,890 --> 00:07:23,160 Now this is the actual pixel information and color mappings within the image. 99 00:07:23,250 --> 00:07:29,100 But in the next lecture, we'll be learning how to utilize tools to help us visualize some of this type 100 00:07:29,100 --> 00:07:31,740 of information we may be getting from our robots. 101 00:07:33,270 --> 00:07:39,330 Then the last thing I want to cover were some of the improvements made related to bag files in the latest 102 00:07:39,330 --> 00:07:41,190 Ross Humboldt distribution. 103 00:07:42,640 --> 00:07:47,320 If you head over to the Ross to Humble page, you will see the changes made since Fox in Galactic and 104 00:07:47,320 --> 00:07:48,640 in the Ross to back section. 105 00:07:48,640 --> 00:07:53,830 We see there is now support for setting the start time of a bag file as well as playing in pausing bag 106 00:07:53,830 --> 00:07:55,570 files as well as a burst mode. 107 00:07:55,570 --> 00:07:59,020 If you're doing things such as training or testing neural network models. 108 00:07:59,230 --> 00:08:05,170 You can also edit bag files to do things such as remove certain topics or merge multiple bag files together. 109 00:08:06,390 --> 00:08:06,930 All right. 110 00:08:06,930 --> 00:08:10,200 With that, let's review what we learned about bag files. 111 00:08:11,510 --> 00:08:16,880 In this lecture, we learned how to use the bank file terminal commands in ROS two. 112 00:08:17,060 --> 00:08:24,320 This includes the ROS two bag record command, which we can specify topics or use the dash a flag to 113 00:08:24,320 --> 00:08:30,080 record all topics and then use the dash o flag to name the bag file output. 114 00:08:30,110 --> 00:08:35,660 We also learned about the ROS to bag info command which will give us information about a bag file. 115 00:08:36,080 --> 00:08:42,200 Then we can actually go ahead and play the bag file back using the ROS to bag play command. 116 00:08:42,230 --> 00:08:47,630 We use the dash WL flag for this command to loop the playback over so the bag file doesn't just stop 117 00:08:47,630 --> 00:08:49,260 playing once it reaches the end. 118 00:08:49,280 --> 00:08:51,710 Instead recycles back at the beginning.