WEBVTT 00:00.050 --> 00:03.050 This is the solution for the activity on launch files. 00:03.050 --> 00:06.800 And in this activity, the challenge is to start a bunch of nodes. 00:06.800 --> 00:10.700 So you have the image provided in the description of the activity. 00:10.700 --> 00:14.060 And we are going to try to get the same thing on Actigraph. 00:14.060 --> 00:20.180 So what you could do first before writing the launch file is to start all the nodes one by one. 00:20.210 --> 00:20.420 Okay. 00:20.450 --> 00:22.280 For example, you could do Ros to run. 00:22.280 --> 00:29.750 Let's do an example for the first node Ros to run my we can use the Python one or the C plus plus one. 00:29.750 --> 00:30.800 It doesn't matter. 00:31.790 --> 00:34.160 Robot news station. 00:34.160 --> 00:37.160 So that's the package name executable name. 00:37.160 --> 00:40.490 And then we actually need to rename it. 00:40.490 --> 00:45.950 So ros args dash r node. 00:46.250 --> 00:53.150 This one is going to be robot News Station discard. 00:53.180 --> 00:54.290 That's the first one. 00:54.290 --> 00:57.950 And we also want to use the uh parameter. 00:57.950 --> 01:02.080 So we had if you don't remember you just start the node like this. 01:02.770 --> 01:03.460 Okay. 01:03.490 --> 01:03.760 You do. 01:03.790 --> 01:05.380 Rows two node list. 01:06.400 --> 01:06.880 Okay. 01:06.880 --> 01:11.890 We have the correct node, then rows two topic list. 01:12.190 --> 01:14.710 So we have the robot news topic. 01:14.710 --> 01:16.480 That's the topic we want. 01:16.840 --> 01:17.710 No problem. 01:17.740 --> 01:20.110 Rows two param list. 01:21.580 --> 01:24.430 And you see we have a robot name parameter. 01:24.430 --> 01:26.890 So I can start again. 01:28.510 --> 01:40.390 So I do my node renaming and then dash p robot name is equal to discard. 01:41.770 --> 01:42.520 All right. 01:43.240 --> 01:45.250 And we have an error. 01:45.700 --> 01:48.040 Yes I forgot the semicolon here. 01:50.170 --> 01:50.560 Okay. 01:50.590 --> 01:51.910 It is started. 01:51.910 --> 01:57.160 And then if I do rows two topic equal with robot news. 01:59.140 --> 02:04.350 You see how this is discard from the robot news station. 02:04.440 --> 02:10.650 All right, so first I did this because well, if you are not sure what to write inside a launch file, 02:10.710 --> 02:13.200 you can just do the Ros two run command first. 02:13.200 --> 02:15.090 And then you have all the information here. 02:15.120 --> 02:18.480 You just need to add the different information here inside the launch file. 02:18.510 --> 02:23.730 And second, you can see that I could have checked the code actually because I've written the code. 02:23.730 --> 02:26.940 But we can find all the information from the terminal. 02:26.940 --> 02:32.490 Even if you don't know the parameter name the topic name, you just start the node and then you discover 02:32.490 --> 02:34.680 them again and you can easily modify them. 02:34.710 --> 02:35.130 All right. 02:35.130 --> 02:39.750 So I'm not going to start the five nodes for the publisher here. 02:39.960 --> 02:45.690 I'm going to directly start a launch file and basically duplicate that with the information for each 02:45.690 --> 02:46.440 node. 02:46.440 --> 02:51.450 So let's go to my robot bring up in the launch I'm going to start. 02:51.450 --> 03:01.200 So I'm going to create a new file named well let's name it radio dot launch dot XML for example. 03:01.230 --> 03:03.810 Just make sure you have that launch XML. 03:03.980 --> 03:08.930 Then we initialize the launch file with launch tag. 03:08.930 --> 03:10.370 And that's it. 03:10.400 --> 03:13.040 Let's start one node. 03:13.880 --> 03:17.270 So pkg is going to be my. 03:17.690 --> 03:19.370 Let's use the Python one. 03:21.080 --> 03:28.460 And exec is going to be if you don't remember you go back here robot news station. 03:29.780 --> 03:33.230 Robot news station. 03:33.710 --> 03:34.550 Great. 03:34.580 --> 03:36.230 Do we need to rename the node. 03:36.230 --> 03:36.950 Yes. 03:36.980 --> 03:39.860 Name and the name? 03:39.890 --> 03:46.490 Well I have just written it here, so I'm going to put it there. 03:46.490 --> 03:50.120 Robot news station discard. 03:50.150 --> 03:51.800 Do I need to add a namespace? 03:51.800 --> 03:54.050 Well, I didn't give you this in the challenge. 03:54.050 --> 03:57.110 You can if you want but I'm going to keep it like this. 03:57.380 --> 04:01.940 I'm going to then close this like that. 04:01.940 --> 04:06.660 I'm going to close the node tag like this because I need to provide a parameter. 04:06.660 --> 04:11.280 So param name value. 04:13.020 --> 04:16.290 What is the name of the parameter you see? 04:16.320 --> 04:19.260 Robot name and the value is that one. 04:19.260 --> 04:21.180 So robot name. 04:24.150 --> 04:26.490 And just just got. 04:27.120 --> 04:34.200 So if I save that if I try to run it I should have the same thing as this roster run command. 04:34.230 --> 04:35.760 Let's try that first. 04:36.510 --> 04:43.350 Let's go to roster Workspace and let's do a call on build packages. 04:43.350 --> 04:47.490 Select with my robot bring up. 04:49.140 --> 04:51.180 Okay let's source. 04:52.260 --> 04:55.260 And let's do a roster launch. 04:55.440 --> 04:56.610 And the name is. 04:56.610 --> 05:00.780 So first the package my robot bring up. 05:00.780 --> 05:05.160 And the name is radio dot launch dot XML. 05:07.910 --> 05:08.750 Okay. 05:08.750 --> 05:12.410 Looks like it is working, I can. 05:12.500 --> 05:15.110 Well, let's do the Rostopic echo. 05:15.140 --> 05:22.670 It correctly works ros2 Ros two node list. 05:23.210 --> 05:24.590 Okay, that's what we want. 05:24.620 --> 05:26.720 So if I do arc graph. 05:29.000 --> 05:35.480 Also you see that we have the first part already correct. 05:36.170 --> 05:38.390 And now for the other publishers. 05:38.390 --> 05:40.880 So the other node is going to be very easy. 05:40.880 --> 05:45.200 I'm going to just take that node here and we need it five times. 05:45.200 --> 05:51.380 So 234 and five I could change the package and use the cplusplus if I want. 05:51.410 --> 05:52.790 I'm just going to use the same. 05:52.820 --> 05:57.890 The executable name is going to be the same every time, but then the node name of course we need to 05:57.890 --> 05:58.940 change it. 05:59.090 --> 06:02.900 So I'm going to put Vb8 here. 06:02.900 --> 06:05.690 I'm going to put the needle. 06:05.690 --> 06:09.460 And here I'm going to put gender. 06:09.460 --> 06:13.570 And here finally C-3po. 06:13.990 --> 06:15.220 Oh okay. 06:15.250 --> 06:17.440 Note that I put everything in lowercase here. 06:17.440 --> 06:20.230 And then let's also change the parameter name. 06:20.890 --> 06:22.360 Uh, maybe eight. 06:25.000 --> 06:28.990 To nil and here gender. 06:28.990 --> 06:32.860 And here C-3po. 06:33.700 --> 06:34.570 All right. 06:34.570 --> 06:37.480 And you see with this I'm going to start five nodes. 06:37.510 --> 06:48.880 Let's save let's build let's source and let's start. 06:49.840 --> 06:52.240 You see we have five processes here. 06:52.240 --> 06:57.580 So the executable names are robot new station 123. 06:57.610 --> 06:58.900 That's the executable name. 06:58.930 --> 06:59.500 Okay. 06:59.680 --> 07:03.700 And then we have the different node names that we can find with acute graph. 07:04.540 --> 07:05.140 Okay. 07:05.170 --> 07:05.860 All good. 07:05.860 --> 07:06.850 That's what we want. 07:06.880 --> 07:13.050 And we can check also that if I do rows two topic equal robot news. 07:13.410 --> 07:20.850 You see, we should receive all of the different, uh, messages from all the publishers with all the 07:20.850 --> 07:21.810 different names. 07:21.840 --> 07:25.710 Okay, because of the parameter that we have set here. 07:25.740 --> 07:28.650 Now finally I'm going to add another node. 07:28.650 --> 07:32.250 This one is so from package. 07:32.880 --> 07:34.740 Let's also use the Python one. 07:34.740 --> 07:38.070 So my pi pg. 07:38.430 --> 07:48.840 If you don't remember you can do for example rows to run my pi PG and it's going to be smartphone. 07:49.260 --> 07:50.700 I'm just going to use it like that. 07:50.700 --> 07:58.020 So exec smartphone and I don't need to provide any renaming. 07:58.020 --> 07:59.910 I don't need to remap anything. 07:59.910 --> 08:02.520 There is no namespace is no parameter. 08:02.520 --> 08:05.040 So just one line. 08:06.000 --> 08:09.710 And now well let's remove that. 08:10.220 --> 08:11.720 Let's stop. 08:11.720 --> 08:14.840 And we're going to build again. 08:15.890 --> 08:20.420 We're going to source again and run again. 08:20.450 --> 08:21.590 Actually launch again. 08:21.590 --> 08:28.580 You see now we have also smartphone and we have the logs because this node is going to receive all the 08:28.580 --> 08:34.490 information from the topic and print the log if I do arc graph. 08:37.550 --> 08:38.090 All right. 08:38.090 --> 08:43.370 And that's exactly the image that you could see on the challenge for this activity. 08:43.370 --> 08:46.250 So maybe the order of the nodes here is not exactly the same. 08:46.250 --> 08:49.100 But this you cannot really control it on a graph. 08:49.100 --> 08:50.900 But well that's the same thing. 08:51.080 --> 08:54.110 Now I'm going to stop that. 08:54.110 --> 09:01.610 And as an extra step of this activity, I also told you you could load the parameters from a YAML file. 09:01.610 --> 09:07.970 So here it's not really going to reduce the amount of lines in the code, because we just have one parameter 09:07.970 --> 09:09.050 for each node. 09:09.050 --> 09:13.690 But still to practice, let's create a YAML file in the config. 09:14.200 --> 09:17.380 We can create a new file and the name is going to be. 09:17.410 --> 09:23.170 Well, let's name it radio Config.yaml for example. 09:24.850 --> 09:32.080 And then we are going to add for example for the first one we have the name here Robot News Station 09:32.080 --> 09:32.920 discard. 09:32.920 --> 09:39.580 And I'm going to add a slash because here those are the parameters that are going to be loaded for that 09:39.580 --> 09:41.380 name for that node. 09:41.380 --> 09:47.620 And when we run the node well if you remember we had a slash in front okay. 09:47.650 --> 09:51.910 So even if you don't provide it in the code there's going to be one that will be added. 09:51.910 --> 09:54.490 So we need to add it here for the parameters as well. 09:54.910 --> 10:00.790 And then we have Ross double underscore parameters. 10:00.910 --> 10:09.160 And we have one parameter named robot name which is a string. 10:09.190 --> 10:10.630 So we put a string. 10:10.660 --> 10:11.270 All right. 10:11.270 --> 10:13.640 And that's for one node. 10:13.670 --> 10:15.800 Now we need to do the same for all the nodes. 10:15.800 --> 10:20.240 So I'm going to just copy this and paste it five times. 10:20.240 --> 10:24.290 So actually three four and five. 10:24.290 --> 10:27.740 And I'm going to make sure that I use the correct name. 10:29.060 --> 10:29.780 Okay. 10:30.110 --> 10:36.380 So in this case better to just copy directly the names. 10:39.830 --> 10:41.510 So that one. 10:41.540 --> 10:44.420 And then that's going to be it. 10:44.990 --> 10:50.540 And then I'm also going to use the value for the parameters here. 10:51.740 --> 10:52.850 That one. 10:55.310 --> 10:56.960 That one also. 10:58.280 --> 10:59.900 And the last one. 11:02.630 --> 11:03.290 Okay. 11:03.290 --> 11:05.990 Just have a quick look that is working. 11:05.990 --> 11:11.300 And you can see from one YAML file we have all the parameters for five nodes. 11:11.300 --> 11:16.570 And so now if you had, let's say, ten parameters for each node, you see, you could add all the parameters 11:16.570 --> 11:17.050 here. 11:17.050 --> 11:20.620 And then you would just need to load the param once. 11:20.620 --> 11:26.500 So let's save that file is going to be installed automatically because we already have the line in the 11:26.860 --> 11:27.610 List.txt. 11:27.640 --> 11:30.430 You see we already installed the config folder. 11:30.730 --> 11:33.910 Let's go back to our launch file. 11:33.910 --> 11:36.640 And I'm going to use the param tag. 11:36.640 --> 11:41.200 But instead of name and value I'm going to use from okay. 11:41.230 --> 11:44.560 So we use the same thing we did for this. 11:44.560 --> 11:46.750 So from and then find. 11:47.830 --> 12:06.910 So dollar sign parentheses find pkg share my robot bring up slash config slash radio config dot YAML 12:06.940 --> 12:08.320 okay you see that's the package. 12:08.320 --> 12:09.610 Name this one. 12:09.610 --> 12:11.050 And then the config folder. 12:11.050 --> 12:14.100 And then the file name radio Config.yaml. 12:14.700 --> 12:17.790 And the good thing is the param file. 12:17.790 --> 12:23.130 So the YAML file is the same for all the nodes because it contains the information for all of them. 12:23.130 --> 12:27.090 So I can just add it to all of the nodes. 12:27.120 --> 12:28.410 It's going to be the same. 12:28.980 --> 12:29.520 All right. 12:29.520 --> 12:34.980 So now you can see the only difference between this and that for example is the name of the node. 12:35.580 --> 12:38.190 I'm going to save it. 12:38.730 --> 12:41.580 And well let's just build and run. 12:41.580 --> 12:43.050 It's going to do the same thing. 12:43.080 --> 12:48.660 But let's just check source and launch. 12:49.800 --> 12:50.520 Okay. 12:51.150 --> 12:57.750 So well you see we receive from the smartphone node, we receive all of the correct, uh, topic data. 12:57.750 --> 13:02.910 So this is working which means that the parameters are working. 13:03.060 --> 13:06.240 And let's just do a quick graph here. 13:07.530 --> 13:08.820 And it's still the same. 13:08.820 --> 13:12.000 So everything is working correctly. 13:12.000 --> 13:14.490 And well that's the end of this activity.