WEBVTT 00:00.140 --> 00:07.100 In this laboratory lesson, we will add support for the Ros2 control library to our robot so that we 00:07.100 --> 00:12.770 can start the robot's joint control system when we launch the gazebo simulation. 00:13.190 --> 00:21.200 To do this, we will need to slightly modify the Urdf model of our robot and add some tags and plugins 00:21.200 --> 00:28.370 that are required by the Ros2 control library for the simulation in gazebo and for the proper functioning. 00:28.370 --> 00:30.620 So back to Visual Studio Code. 00:30.620 --> 00:37.640 Let's open the Arduino board description package and here within the Urdf folder, let's continue modifying 00:37.640 --> 00:38.630 this file here. 00:38.630 --> 00:44.750 So the Arduino bot dot Urdf dot acro here at the beginning of this file. 00:44.750 --> 00:46.310 So we can do it here. 00:46.310 --> 00:53.840 Let's declare a new macro argument with the tag macro argument. 00:53.960 --> 00:59.060 And let's close it here within the same line and accept the argument. 00:59.090 --> 01:03.240 Basically works like a variable for other programming languages. 01:03.240 --> 01:10.770 In fact, we are going to use this argument, this variable, in order to load the proper version of 01:10.770 --> 01:13.380 the Ros2 control plugin for gazebo. 01:13.380 --> 01:19.770 In fact, you will need to load a different Ros2 control plugin for gazebo depending on which Ros2 version 01:19.770 --> 01:20.820 you are using. 01:20.850 --> 01:23.430 So let's call this variable. 01:24.300 --> 01:29.490 Is ignition perfect and by default. 01:31.860 --> 01:35.070 Let's set it to true. 01:35.100 --> 01:36.030 Perfect. 01:36.030 --> 01:37.950 And that's it for this file. 01:37.950 --> 01:43.380 So for this file we just need actually to declare this argument here that now we are going to use in 01:43.380 --> 01:47.040 order to decide which Ros2 control plugin to load. 01:47.160 --> 01:54.030 Now instead of configuring the gazebo plugins and the Ros2 control library in this same file. 01:54.030 --> 01:57.300 So in the Arduino board Erfc Sacro. 01:57.300 --> 02:02.610 And so this will create a huge and hard to read CSV file. 02:02.610 --> 02:07.770 So this is already pretty huge and only contains the links and the joints of the robot. 02:07.800 --> 02:14.010 Now, instead of adding to this file, also the configuration for the gazebo and for the Ros2 control 02:14.010 --> 02:16.740 library, we can do it in a different file. 02:16.740 --> 02:23.850 So we can use another interesting feature of the exact format that is to include a Docker file from 02:23.850 --> 02:25.470 another profile. 02:25.470 --> 02:28.410 So basically we can create a new file. 02:28.410 --> 02:35.370 And for example let's call it Arduino robot gazebo dot Sacro. 02:35.370 --> 02:37.560 So for the moment this is an empty file. 02:37.560 --> 02:40.560 But the cool thing is that we can include. 02:40.560 --> 02:47.910 So here with the Sacro include like this. 02:47.910 --> 02:52.560 We can include the file name that we have just created. 02:52.560 --> 02:58.830 So let's find within the Arduino bot. 03:00.180 --> 03:01.530 description package. 03:01.530 --> 03:04.470 And from this package here we want to load. 03:04.470 --> 03:16.230 So from the Urdf folder we want to load the Arduino bot gazebo dot profile. 03:16.230 --> 03:17.130 Perfect. 03:17.130 --> 03:26.100 And so this instruction here basically so these include instruction is equivalent to copy all the content 03:26.100 --> 03:30.300 of this file here that now we are going to create just copy pasting it here. 03:30.300 --> 03:33.270 So this instruction is exactly equivalent. 03:33.270 --> 03:39.210 And the advantage of course is that we have separated all the links and the joints that are declared 03:39.210 --> 03:44.700 here in this Sacro file from the gazebo configuration that we are going to insert here. 03:44.700 --> 03:47.610 And so this is now easier to maintain. 03:47.610 --> 03:53.820 So if we want to load a new gazebo plugin, or if we want to change the configuration for our gazebo 03:53.820 --> 03:55.590 simulation, we just need to touch. 03:55.590 --> 04:01.390 So to modify this file here and instead this one will just contain the links and the joints of the robot, 04:01.390 --> 04:03.550 and so it will not change. 04:03.580 --> 04:04.480 Perfect. 04:04.480 --> 04:06.910 So let's start also this file here. 04:06.910 --> 04:08.800 So the Arduino board the gazebo file. 04:08.800 --> 04:12.970 And actually we can copy the first line from this one here. 04:12.970 --> 04:15.580 So from the Arduino bot Urdf dot sacro. 04:15.580 --> 04:18.040 So let's copy and let's paste it. 04:18.040 --> 04:21.220 In fact this is still an XML file. 04:21.220 --> 04:24.550 And then we have opened the robot tag. 04:24.550 --> 04:27.370 And here our robot is called Arduino bot. 04:27.400 --> 04:32.230 Also in this case let's insert the closing tag for the robot tag. 04:32.260 --> 04:33.010 Perfect. 04:33.010 --> 04:40.030 And now we can actually start configuring gazebo so we can actually start loading the gazebo plugins. 04:40.030 --> 04:44.470 To do so we can use the tag gazebo. 04:44.470 --> 04:51.640 And now in this tag we need to load a different Ros2 control plugin for the gazebo depending on the 04:51.640 --> 04:53.590 Ros2 version that you are using. 04:53.680 --> 04:57.700 So to do so, we can use the exact argument that we have created here. 04:57.710 --> 05:00.260 So this exact argument here. 05:00.260 --> 05:06.860 And so we can check its value with the exact row if perfect. 05:07.040 --> 05:13.400 And now let's check the value of the is ignition argument. 05:14.210 --> 05:19.370 So if the argument is ignition perfect. 05:19.370 --> 05:23.300 So we are checking the value of this one. 05:23.300 --> 05:29.300 And if this one is set to true in this case it means that you are using ros2 humble. 05:29.300 --> 05:35.300 And so if you are using Ros2 humble you need to load the plugin that is called. 05:35.300 --> 05:49.340 So here the file name is called ignition Ros2 Control system and the name of the class that we want 05:49.340 --> 05:51.320 to load from this plugin here. 05:52.370 --> 05:57.890 So the name is the from the package ignition Ross two. 05:59.750 --> 06:03.920 Control is the ignition. 06:04.610 --> 06:09.200 Ross two control plugin. 06:09.260 --> 06:10.310 Perfect. 06:10.430 --> 06:17.630 Eventually we can also configure this plugin here with some parameters with the tag parameters. 06:17.630 --> 06:22.850 And for the moment we can leave this tag here empty as we are going to configure it. 06:22.850 --> 06:24.620 So we are going to modify it. 06:24.650 --> 06:27.560 We are going to assign some parameters to this plugin. 06:27.560 --> 06:32.210 When in the following lessons we will learn about YAML files. 06:32.510 --> 06:33.350 Perfect. 06:33.350 --> 06:38.060 And so this is if you are using the humble version of Ross two. 06:38.090 --> 06:39.050 Otherwise. 06:39.050 --> 06:44.060 So let's use the exact pro and less perfect. 06:44.060 --> 06:58.700 And if the value of the argument is ignition is set to false, it means that you are using a newer version 06:58.700 --> 07:01.670 of Ros2, and so you need to load a different plugin. 07:03.440 --> 07:03.980 Perfect. 07:03.980 --> 07:05.690 And the file name. 07:05.840 --> 07:20.540 So here the file name that you need to load is called gazebo underscore Ros2 control system. 07:20.660 --> 07:29.960 And the name of the class that we want to load from this plugin is from the gazebo Ros2 control package. 07:30.170 --> 07:40.340 And then the class is called gazebo SIM Ros2 control plugin. 07:40.340 --> 07:41.120 Perfect. 07:41.150 --> 07:45.140 Also in this case we can configure this plugin here with some parameters. 07:45.140 --> 07:47.660 So we can copy the parameters tag. 07:47.660 --> 07:53.480 And also in this case actually we can leave this one empty as we will come back to modify this file 07:53.480 --> 07:57.210 in the future when we will learn about YAML files. 07:58.350 --> 08:04.470 For the moment, we have done with this file so we can save it, and we can move on to the creation 08:04.470 --> 08:06.510 of another exact file. 08:06.510 --> 08:15.030 So still here, still in the Urdf folder, let's create a new file and let's call it Arduino bot Ros2 08:16.350 --> 08:19.230 control dot sacrum. 08:19.230 --> 08:25.530 And as the name of this file suggests, basically here in this new file we are just going to insert 08:25.530 --> 08:28.890 the Ros2 control configuration for our robot. 08:28.890 --> 08:34.890 And actually this one will contain both the Ros2 control configuration for the simulated robot. 08:34.890 --> 08:40.560 And also in the following sections of this course, it will contain the Ros2 control configuration for 08:40.560 --> 08:42.570 the real robot as well. 08:42.630 --> 08:45.960 Now remember that we have declared a new macro file. 08:45.960 --> 08:50.310 And so actually we can include it here in the main urdf file. 08:50.310 --> 08:55.200 So this one here will be the one that we will load with the robot state publisher. 08:55.210 --> 09:02.740 So we can copy this include statement and we can paste it in order to include also the file that we 09:02.770 --> 09:03.970 have just created. 09:03.970 --> 09:11.500 And that is called Arduino bot Ros2 control dot Sacro. 09:11.500 --> 09:17.350 And so remember that this instruction here is equivalent to copying all the content of this file here 09:17.350 --> 09:20.830 that we are going to create right now and pasting here. 09:20.830 --> 09:26.110 And the advantage is of course, that we have smaller files that we can maintain easily. 09:26.230 --> 09:33.280 So again let's copy the first two instructions of this file and let's paste them here within the Arduino 09:33.280 --> 09:34.480 bot to control. 09:34.480 --> 09:37.690 Let's also close the robot tag. 09:37.720 --> 09:38.410 Perfect. 09:38.410 --> 09:40.480 And now within this tag here. 09:40.480 --> 09:46.030 So within the robot tag we can start configuring the Ros2 control library for our robot. 09:46.030 --> 09:52.330 We can do so using the Ros2 control tag. 09:52.360 --> 09:56.230 Perfect and now here let's set the type. 09:57.970 --> 10:01.210 And the type that we want to represent is a complete system. 10:01.210 --> 10:04.720 So a complete robot composed of several joints. 10:04.720 --> 10:08.170 So let's set the type to system. 10:08.170 --> 10:15.730 And also we can set the name to robot system perfect. 10:15.760 --> 10:19.390 Also in this case so also in the Ros2 control tag. 10:19.420 --> 10:25.420 Depending on the Ros2 version that you are using, you need to load a different Ros2 control plugin 10:25.420 --> 10:27.610 for the hardware interface. 10:27.610 --> 10:32.500 So for interacting with the simulated hardware on gazebo for this reason. 10:32.500 --> 10:35.920 Also in this case we can use the is ignition variable. 10:36.070 --> 10:41.260 So let's check whether the variable. 10:42.880 --> 10:52.270 So the value of the argument is ignition is set to true. 10:52.300 --> 10:54.490 Again if this one is set to true. 10:54.520 --> 11:00.550 It means that you are working with Ros2 humble, and in this case, you need to load the hardware interface. 11:01.600 --> 11:03.610 So let's call it hardware. 11:03.610 --> 11:12.190 And this is implemented in the plugin that is from the ignition Ros2 control library. 11:12.190 --> 11:17.260 And that is called ignition system. 11:17.260 --> 11:17.890 Perfect. 11:17.890 --> 11:24.460 And so this is the hardware interface for the simulated robot that you need to load if you are working 11:24.460 --> 11:26.320 with Ros2 Campbell. 11:26.350 --> 11:27.550 Otherwise. 11:28.120 --> 11:41.680 So sacral unless if the value of the argument is ignition is set to false. 11:41.680 --> 11:43.450 So it means that we are here. 11:43.450 --> 11:50.230 And so it means that on your PC you have installed a newer version of Ros2, like for example Ros2 Jessie. 11:50.290 --> 11:58.610 In this case the Hardware interface that you need to load is defined in the plugin that is from the 11:58.610 --> 12:09.200 gazebo Ros2 control library, and that is called gazebo SIM system. 12:09.200 --> 12:09.950 Perfect. 12:09.950 --> 12:15.710 And so with this one here, we have loaded the Arduino interface for the simulated robot. 12:15.710 --> 12:21.110 Whether you are using Ros2 humble or whether you are using any newer version. 12:21.140 --> 12:27.500 Now in the last section of this course, actually, we will come back to modify this file here. 12:27.500 --> 12:34.520 So the Arduino Ros2 control file in order to add another hardware interface, this time not with gazebo, 12:34.520 --> 12:36.680 but for the real robot. 12:36.680 --> 12:42.950 So the Arduino interface that will actually communicate with the real motors, that will drive the real 12:42.950 --> 12:44.060 robot arm. 12:44.750 --> 12:49.610 For the moment, let's just conclude the configuration of the Ros2 control plugin. 12:49.640 --> 12:57.150 Also, by adding some joint tag in order to define the interface that each movable joint of the robot 12:57.180 --> 13:01.470 has to use in order to interact with the Ros2 control library. 13:01.500 --> 13:06.060 Namely, each joint will specify how it will be controlled. 13:06.360 --> 13:13.980 So let's start with the first joint that is called joint one. 13:13.980 --> 13:20.520 And now, as you may recall from the theoretical lessons to connect the Ros2 control library to an hardware 13:20.520 --> 13:21.240 interface. 13:21.240 --> 13:28.440 So to an hardware resource, we need to define the two interfaces for communicating with the resource. 13:28.440 --> 13:32.640 And the first interface is called command. 13:34.680 --> 13:35.850 Interface. 13:35.850 --> 13:36.750 And this one. 13:36.750 --> 13:41.910 So the command interface is the one that we use in order to send commands to the hardware. 13:41.910 --> 13:44.670 So to send commands to the motors. 13:44.670 --> 13:49.410 And then there is also another interface that instead is called state 13:51.390 --> 13:54.990 Interface, we can close it in the same line. 13:54.990 --> 13:55.620 Perfect. 13:55.620 --> 13:57.270 And the second interface. 13:57.270 --> 14:05.370 So the state interface instead is used for reading the feedback from the hardware, namely to read the 14:05.370 --> 14:11.430 current state of the motor and for example, to read the current position or the current velocity of 14:11.430 --> 14:13.560 the motors in both cases. 14:13.590 --> 14:19.290 So for the command interface we want to use a position interface. 14:19.470 --> 14:25.590 So let's set the name to be position for the command interface. 14:25.590 --> 14:30.510 And also we can copy this one and we can set it here for the state interface. 14:30.510 --> 14:37.170 So we want to use a position interface both for sending commands to the hardware and also for receiving 14:37.170 --> 14:37.770 its feedback. 14:37.770 --> 14:40.530 So we want to know the position of the motors. 14:40.530 --> 14:45.060 And also we want to send the commands expressed in the position of the robot. 14:45.060 --> 14:51.300 And here in the command interface, we can also limit the maximum and the minimum command that we want 14:51.300 --> 14:52.170 to set. 14:52.410 --> 14:55.710 So let's set the parameters. 14:56.700 --> 15:00.450 So the name is called min. 15:00.510 --> 15:06.930 And also let's set another parameter for the command interface that is called max. 15:06.960 --> 15:12.570 And so this one is in order to limit the rotation of the first joint. 15:12.570 --> 15:19.860 And for the first joint we want to limit it from -90 degrees to 90 degrees. 15:19.860 --> 15:23.400 So actually this has to be expressed in radians. 15:23.400 --> 15:31.080 So if we go back here in the Arduino urdf we can copy the declaration of this variable here. 15:31.080 --> 15:33.570 And we can use it here as well. 15:34.050 --> 15:35.880 So let's paste it. 15:35.880 --> 15:36.630 Perfect. 15:36.630 --> 15:41.400 And now we can use this variable in order to define the minimum that is minus. 15:43.050 --> 15:48.660 And then the variable pi divided by two. 15:48.690 --> 15:49.440 Perfect. 15:49.440 --> 15:50.760 And the maximum. 15:50.800 --> 15:52.390 so we can copy this one. 15:52.390 --> 15:55.390 It's simply pi divided by two. 15:55.420 --> 15:58.150 So as we said 90 degrees. 15:58.240 --> 15:59.020 Perfect. 15:59.020 --> 16:01.900 And with this one we have completed the joint one. 16:01.900 --> 16:04.810 Now we are missing all the other joints of the robot. 16:04.840 --> 16:10.780 However, since all the movable joints of the robot will use the same command interface and will also 16:10.780 --> 16:19.030 provide the same state interface, we can simply copy paste this same instruction and we can use it 16:19.030 --> 16:20.770 for the joint two. 16:21.640 --> 16:24.670 Then we can paste it also for the joint three. 16:24.670 --> 16:28.060 And with this we have completed the joints of the arm. 16:28.090 --> 16:33.280 And then let's also set it for the joints of the gripper that are the joint four. 16:33.730 --> 16:37.210 And also we have the joint five. 16:37.240 --> 16:38.050 Perfect. 16:38.050 --> 16:45.220 Now we need to do some few changes, especially for these last two joints which control the fingers 16:45.220 --> 16:46.480 of the gripper. 16:46.480 --> 16:48.730 And actually these two joints here. 16:48.730 --> 16:53.960 So the joint four and the joint five are not independent, but they will move together. 16:53.960 --> 16:56.780 In fact, they are connected with a gearbox. 16:56.780 --> 17:04.100 And so, for example, when the joint four opens, also the joint five will open as they are moved together 17:04.100 --> 17:05.840 by the same motor. 17:05.930 --> 17:08.240 For this reason we need to set. 17:08.270 --> 17:12.230 So here for the joint four we need a different limit. 17:12.230 --> 17:15.710 And so the minimum is still -90 degree. 17:15.710 --> 17:22.220 But then when it closes it reaches the maximum position of 0.0. 17:22.220 --> 17:22.910 Perfect. 17:22.910 --> 17:26.720 And this is for the joint four instead for the joint five. 17:26.720 --> 17:32.030 So here this one will actually not have its own command interface. 17:32.030 --> 17:33.710 So we can remove it. 17:33.710 --> 17:37.550 And it will not have its state interface. 17:37.550 --> 17:39.320 So we can remove also this one. 17:39.320 --> 17:43.370 And this is because the joint five is not, as I said, the independent. 17:43.370 --> 17:48.050 But the joint five will simply mimic the behavior of the joint four. 17:48.080 --> 17:54.530 And now in order to indicate also to the Ros2 control library that this joint here will replicate. 17:54.530 --> 17:57.440 So we'll mimic the behavior of the joint for. 17:57.440 --> 18:00.080 We need to set here a parameter. 18:01.970 --> 18:08.210 So let's set the parameter that is called mimic. 18:11.120 --> 18:17.750 And here let's set the name of the joint that this joint here so that the joint five will mimic. 18:17.750 --> 18:21.200 And this is the joint four. 18:21.200 --> 18:26.660 And so with this parameter we are simply saying to the Ros2 control library that the joint five will 18:26.660 --> 18:28.760 move as the joint four. 18:28.760 --> 18:32.090 And then let's also set another parameter. 18:32.480 --> 18:36.170 And this one is called multiplier. 18:37.460 --> 18:40.070 And let's set it to minus one. 18:40.070 --> 18:48.170 And this simply indicates that the joint five will move as the joint four but in the different direction. 18:48.170 --> 18:56.120 So for example if the joint four will move 45 degrees, the joint five will move -45 degrees. 18:56.120 --> 19:00.110 And so this is because we have set the multiplier to minus one. 19:00.110 --> 19:05.270 So the intensity of the two movements will be the same but in the opposite direction. 19:05.660 --> 19:06.530 Perfect. 19:06.530 --> 19:08.300 So we can save this file. 19:08.300 --> 19:11.990 And with this we have completed the Urdf model of our robot. 19:12.020 --> 19:17.900 To support also the usage of the Ros2 control library in the gazebo simulation. 19:17.900 --> 19:23.570 And so here we have added we have loaded the proper Ros2 control plugin for gazebo. 19:23.570 --> 19:25.760 And here we have configured it. 19:25.760 --> 19:31.880 So we have configured all the joints of our robot in order to be actuated in the gazebo simulation. 19:31.910 --> 19:37.400 Now as we have added, as you can see here, the dependencies from these two libraries. 19:37.400 --> 19:46.400 So from the ignition cross to control if you are on Ros2 or from gazebo Ros2 control if you are on Ros2. 19:46.430 --> 19:50.130 Jazzy, we need to declare these dependencies also here. 19:50.130 --> 19:52.290 So in the package dot XML. 19:52.290 --> 20:00.180 So here let's add an execution dependency from the gazebo Ros2 control. 20:00.210 --> 20:06.300 However, as I said you're going to need this package here only if you are on newer version of Ros2. 20:06.300 --> 20:08.640 So for example, only if you are on Ros2. 20:08.670 --> 20:09.240 Jessie. 20:09.420 --> 20:12.270 So let's add a conditional dependency. 20:13.230 --> 20:18.690 So we want to add this dependency only if this condition is satisfied. 20:18.690 --> 20:22.050 And the condition that we want to verify is that the variable. 20:22.050 --> 20:26.820 So the environmental variable that is called Ros distro. 20:26.820 --> 20:31.320 So this variable here is bigger than or equal to iron. 20:31.320 --> 20:36.120 So if you are working with a ros2 version that is newer than iron. 20:36.120 --> 20:40.470 And for example if you are working with Jessie you need this package here. 20:40.530 --> 20:47.010 Otherwise let's add another execution dependency, this time from the ignition Ros2. 20:48.220 --> 20:49.480 Control package. 20:49.480 --> 20:51.700 And you need this package here only. 20:51.700 --> 20:57.460 If so, the condition is that you have the Ros distro. 20:59.890 --> 21:04.960 So the Ros version that you are using is equal to humble perfect. 21:04.960 --> 21:10.930 So if you are on Ros two humble you are going to need this package here. 21:10.930 --> 21:16.270 Otherwise if you are on any newer version you are going to need this other package here. 21:16.330 --> 21:19.270 So let's save also this file and that's it. 21:19.390 --> 21:24.400 Later in the course we will return to modify especially this file here. 21:24.400 --> 21:31.960 So the Arduino Ros to control file in order to add the support not only to the simulated hardware interfaces. 21:32.080 --> 21:37.120 So these other interfaces that will communicate with the simulated motors in gazebo. 21:37.120 --> 21:40.990 But also we will add the support to the real hardware interface. 21:40.990 --> 21:46.930 So to the hardware interface that will interact with the real motors and with the real robot.