WEBVTT 00:00.050 --> 00:06.620 In this laboratory lesson, we are going to create a simple script, a simple Python node that uses 00:06.620 --> 00:14.180 the V2 APIs in order to send a goal to the robot and move it to a desired position. 00:14.180 --> 00:21.530 Before following this lesson, please mind that the Python API for Moovit was introduced in Ros two 00:21.530 --> 00:22.100 iron. 00:22.100 --> 00:29.600 So if you are using an older Ros two version like for example Ros2 humble, it will not be available 00:29.600 --> 00:36.380 and you can only interact with Moovit using the Cplusplus API that will be developed in the following 00:36.380 --> 00:37.760 laboratory lesson. 00:37.910 --> 00:45.890 So back in Visual Studio Code, let's start by creating our simple script in the Arduino Bot Pi examples 00:45.890 --> 00:46.430 folder. 00:46.430 --> 00:47.690 So this one here. 00:47.690 --> 00:56.570 And so here within the Arduino Pi example sub folder, let's create a new file called simple Moovit 00:58.150 --> 01:00.160 Interface dot pi. 01:00.190 --> 01:00.820 Perfect. 01:00.820 --> 01:06.490 So here, as always, let's start by importing the CLP library. 01:06.520 --> 01:07.120 Perfect. 01:07.120 --> 01:12.220 That is the interface that we can use in order to interact with the Ros2 functionalities. 01:12.220 --> 01:18.970 And here, since we are implementing a very simple Ros2 node, there is no need actually to create a 01:18.970 --> 01:26.530 new class that inherits from the node class, and instead we can directly instruct all the functions 01:26.530 --> 01:29.290 and so all the code in the main function. 01:29.290 --> 01:31.480 So let's define it. 01:36.970 --> 01:41.350 So here let's execute the main function. 01:41.380 --> 01:42.010 Perfect. 01:42.010 --> 01:43.480 And now let's define it. 01:43.480 --> 01:47.050 So let's define the function main in which. 01:47.050 --> 01:50.410 Now we are going to insert all the code of our robot. 01:50.410 --> 01:53.020 So of our API form of it. 01:53.050 --> 02:01.980 Now here the first thing that we want to do is to initialize the Ros to interface with clp init. 02:02.010 --> 02:02.730 Perfect. 02:02.730 --> 02:06.600 And then also we want to insert all the code that will move the robot. 02:06.600 --> 02:13.050 And so all the logic that interacts with the Moveit API for Python in a new function that we are going 02:13.050 --> 02:15.990 to call move robot. 02:16.020 --> 02:16.560 Perfect. 02:16.560 --> 02:21.990 So this function here will actually be in charge of moving the robot from the current position to a 02:21.990 --> 02:24.870 desired position that we will insert here. 02:24.870 --> 02:30.600 And then after moving the robot, we want to simply shut down this node. 02:30.600 --> 02:34.890 So let's use the CLP shutdown function. 02:34.920 --> 02:35.670 Perfect. 02:35.670 --> 02:38.940 So now we are missing to declare this function here. 02:38.940 --> 02:45.630 So the move robot function in which we will actually insert all the logic for this script here. 02:45.630 --> 02:50.880 So let's here let's define the move robot function. 02:50.880 --> 02:51.600 Perfect. 02:51.600 --> 02:59.500 And now in this move robot function we want to start interacting with the Moovit APIs for Python, and 02:59.500 --> 03:07.450 to do so we can import from the Moovit package and from the planning library. 03:07.510 --> 03:10.930 Let's import the class that is called Moovit Pi. 03:10.960 --> 03:11.800 Perfect. 03:11.800 --> 03:16.660 And so now we can start using this class to interact with the Moovit API. 03:16.930 --> 03:21.970 And so here within the move robot function we can create a new instance of this class. 03:22.090 --> 03:25.480 And let's call it Arduino bot. 03:25.720 --> 03:28.390 So this is an instance of the movie Pi. 03:28.390 --> 03:29.560 And we want. 03:29.590 --> 03:33.910 So this one here under the hood is creating a new Ros2 node. 03:34.270 --> 03:35.440 And let's call it. 03:35.470 --> 03:42.340 So let's give it a name and let's call this node move it Pi. 03:42.370 --> 03:43.270 Perfect. 03:43.630 --> 03:49.600 And so here we have created a new instance of the movie Pi that we have called Arduino bot. 03:49.600 --> 03:51.490 And now using this instance. 03:51.490 --> 03:59.010 So using this object Here, we can access to the two move groups that we have defined in our moved configuration. 03:59.010 --> 04:05.520 So if you remember from the previous lessons when we configured move It, we have defined two move groups, 04:05.520 --> 04:10.170 one for the R so one that moves the R and one for the gripper. 04:10.170 --> 04:13.170 So let's start interacting with the one of the r. 04:13.200 --> 04:17.640 So let's call it Arduino bot arm. 04:18.540 --> 04:19.470 Perfect. 04:19.470 --> 04:26.040 And so from the Arduino bot object let's get a planning component. 04:26.040 --> 04:31.920 So let's use this function here in order to access to the move group that we have called R. 04:32.070 --> 04:33.030 Perfect. 04:33.030 --> 04:35.970 And let's do the same also for the gripper. 04:35.970 --> 04:39.390 So we can copy this line here and we can paste it. 04:39.390 --> 04:43.680 And let's change this variable into Arduino bot gripper. 04:43.680 --> 04:47.250 So with this one here we are accessing to the planning component. 04:47.250 --> 04:52.180 So to the move group that we have called gripper Perfect. 04:52.240 --> 04:57.100 And so with these two variables now we have accessed these two move groups. 04:57.100 --> 05:03.580 Now with the Arduino robot arm and with the Arduino bot gripper variables, we can now access these 05:03.580 --> 05:04.210 two groups. 05:04.210 --> 05:06.280 So the arm and the gripper separately. 05:06.280 --> 05:11.260 And so actually we can send a goal to each of them and then plan trajectories. 05:11.260 --> 05:15.160 And also to execute the goal that we have planned independently. 05:15.160 --> 05:17.710 So we can plan and execute a goal for the arm. 05:17.710 --> 05:22.480 And then we can plan and execute another goal for the gripper to do so. 05:22.480 --> 05:27.250 So to set a goal for the arm, for the gripper we need to import another class. 05:27.490 --> 05:33.970 And this is from the movie package and from the core. 05:34.000 --> 05:40.990 Let's import from the robot state the class that is called robot State. 05:40.990 --> 05:45.700 So as the name of this class suggests, this will contain the state of the robot. 05:45.700 --> 05:51.660 And so actually this can contain both the current state of the robot or also it can contain the desired 05:51.660 --> 05:52.950 state of the robot. 05:52.980 --> 05:59.490 Now let's create two new instances of this variable that is called our state. 05:59.520 --> 06:03.660 And so this is an instance of the robot state. 06:03.660 --> 06:08.340 And let's also create another one that is gripper state. 06:08.340 --> 06:11.790 Again an instance of the robot state class. 06:11.790 --> 06:13.020 And for the moment. 06:13.020 --> 06:15.810 So within this variable we just want to contain. 06:15.810 --> 06:19.140 So we just want to get the current state of the art. 06:19.170 --> 06:27.210 So let's access to the Arduino bot and let's use the Get robot model function. 06:27.210 --> 06:27.960 Perfect. 06:27.990 --> 06:31.470 And also let's do the same here for the gripper. 06:31.680 --> 06:37.170 So let's use the Arduino bot and then the get robot model function. 06:39.510 --> 06:40.440 Perfect. 06:40.440 --> 06:45.930 And now that we have the current state of the joints of the robot that we have created with the two 06:45.960 --> 06:48.250 instances of this class glass here. 06:48.280 --> 06:49.420 Now we can use them. 06:49.420 --> 06:54.550 So we can use these two states to set a goal for the joints of the robot. 06:54.790 --> 07:04.840 And in order to set the goal so we can access the arm state and we can use the set joint group positions 07:04.840 --> 07:05.770 function. 07:05.770 --> 07:14.050 So this function here and also for the gripper let's use the set joint group position perfect. 07:14.050 --> 07:19.750 And for example so for the arm we want to set the position of the joints. 07:19.750 --> 07:24.430 So the desired position for the move group that is called arm. 07:24.430 --> 07:27.730 And we want to set it as a numpy array. 07:27.730 --> 07:30.970 So first let's import the numpy library. 07:31.090 --> 07:36.130 So let's import numpy as np. 07:36.490 --> 07:44.590 And now here so where we are here in the set joint group position let's set the desired position. 07:44.590 --> 07:49.050 So the goal position for the arm is a numpy array. 07:49.620 --> 07:52.050 So here let's set the array. 07:52.050 --> 07:57.810 And here we need to specify the desired position of all the joints that belong to the arm. 07:57.840 --> 08:01.170 So if you remember the arm only has three joints. 08:01.170 --> 08:04.440 So the joint of the base the shoulder and the elbow. 08:04.440 --> 08:08.850 And for example let's just turn the base for 90 degrees. 08:08.850 --> 08:11.550 So 1.57 radians. 08:11.550 --> 08:15.960 And then we can instead set the other joints to zero. 08:15.960 --> 08:22.680 So basically we are setting that the desired position of the arm will just rotate the base joint of 08:22.680 --> 08:23.880 90 degrees. 08:23.910 --> 08:27.000 And then let's also set the desired position for the gripper. 08:28.230 --> 08:28.860 Perfect. 08:28.860 --> 08:32.730 And also in this case this is a numpy array. 08:33.930 --> 08:38.310 And as you remember there are only two joints that belongs to the gripper. 08:38.310 --> 08:44.180 And also these two joints are not independent from each other but they are actuated Treated together. 08:44.180 --> 08:47.510 And so let's for example open the gripper. 08:47.540 --> 08:54.560 And so let's set that the joint number four will rotate of -0.7 radians. 08:54.560 --> 08:59.360 And so the other one the joint number five will rotate the same angle. 08:59.360 --> 09:02.360 So 0.7 but in the opposite direction. 09:02.450 --> 09:03.230 Perfect. 09:03.230 --> 09:06.560 So with this one we have set the goal state of the robot. 09:06.560 --> 09:12.800 So the joints the desired position of the joints of the robot in the goal state. 09:12.800 --> 09:15.860 Now before actually sending these goals to the planner. 09:15.860 --> 09:22.370 So and to calculate the trajectory to these goals here, let's first reset the current state. 09:22.370 --> 09:27.500 So we want first to set the current state of the robot before setting the desired state. 09:27.860 --> 09:31.070 So again let's access to the Arduino robot arm. 09:31.160 --> 09:42.390 And here let's use the function set start state to current State. 09:42.390 --> 09:43.110 Perfect. 09:43.110 --> 09:46.440 So the name of this function is quite self-explanatory. 09:46.470 --> 09:51.900 And so basically we are setting the start state for this object here. 09:51.900 --> 09:54.930 So for the Arduino both are to the current state. 09:54.930 --> 09:56.580 So to the current position. 09:56.580 --> 09:59.820 And so here we have set the start state. 09:59.850 --> 10:01.980 Here we have the goal state. 10:01.980 --> 10:04.410 So the desired goal state of the robot. 10:04.440 --> 10:06.510 Now let's also do the same for the gripper. 10:06.540 --> 10:08.520 So we can copy this instruction here. 10:08.520 --> 10:14.220 And we can set the start state also for the gripper. 10:14.220 --> 10:17.070 So also for the move group of the gripper. 10:17.070 --> 10:20.070 And now we are just missing to set the goal state. 10:20.070 --> 10:29.820 So to take the Arduino robot arm and we can use the set goal state function. 10:29.820 --> 10:32.310 And we want to set the robot state. 10:32.310 --> 10:34.860 And so actually here we can use this object here. 10:34.860 --> 10:39.840 So the arm state object that we have created and in which we have set. 10:39.840 --> 10:41.420 So this one here. 10:41.420 --> 10:43.190 So this position of the joints. 10:43.220 --> 10:46.640 Let's do the same also for the Arduino both gripper. 10:46.640 --> 10:52.520 So here for the gripper let's set the goal state. 10:52.520 --> 10:57.470 And also in this case we want to set the robot state that is this one here. 10:57.470 --> 11:01.700 So the gripper state in which we have set the position. 11:01.700 --> 11:05.720 So a numpy array for the desired configuration of the gripper. 11:05.750 --> 11:06.710 Perfect. 11:06.710 --> 11:11.420 So now we have that for the Arduino robot arm and for the Arduino bot gripper. 11:11.420 --> 11:15.770 So for these two planning components we have set a start state. 11:15.770 --> 11:17.870 We have also set a goal state. 11:17.870 --> 11:18.620 Perfect. 11:18.770 --> 11:25.280 So now we can just plan a trajectory from the start state to the goal state. 11:25.280 --> 11:26.600 And this is pretty easy. 11:26.630 --> 11:33.380 We just need to take the Arduino robot arm and just want to execute the function plan. 11:33.380 --> 11:37.370 And also let's do the same for the Arduino bot gripper. 11:38.440 --> 11:40.570 And let's use the function plan. 11:40.570 --> 11:47.710 So this function here will just calculate a plan that brings the Arduino bot arm from the current position. 11:47.710 --> 11:50.290 So this one here to the goal position. 11:50.290 --> 11:53.050 So to this position here of the joints. 11:53.050 --> 11:56.890 Now let's also save this plan that was generated into a new variable. 11:56.920 --> 12:00.250 And let's call it for example our plan. 12:03.850 --> 12:04.870 Result. 12:04.870 --> 12:09.340 And also here let's call it gripper plan. 12:10.450 --> 12:11.410 Result. 12:11.440 --> 12:11.980 Perfect. 12:11.980 --> 12:15.430 And now let's check whether the plan was successful. 12:15.430 --> 12:21.250 So whether the planner was able to calculate a plan from the current position to the desired position. 12:21.250 --> 12:30.520 And so if the arm plan result and the gripper plan result. 12:30.520 --> 12:36.740 So if the planner was able to calculate a trajectory both for the arm and for the gripper. 12:36.770 --> 12:41.930 Now we finally can execute it so we can execute the trajectory that was calculated. 12:41.990 --> 12:43.580 And this is very simple. 12:43.580 --> 12:45.560 So we can take this object here. 12:45.560 --> 12:53.120 So the Arduino bot that is our robot and we can simply execute this one here. 12:53.120 --> 13:00.800 So from the arm plan result we can take the trajectory. 13:00.800 --> 13:02.540 So we want to execute this trajectory. 13:02.540 --> 13:08.630 And let's also set the controllers to an empty list. 13:08.630 --> 13:13.850 Just in order to use the default controllers that are loaded for the arm. 13:13.880 --> 13:17.120 And let's execute also the trajectory for the gripper. 13:17.120 --> 13:19.430 So still on the Arduino bot object. 13:19.430 --> 13:27.650 So our robot let's execute this time the gripper plan result and also the trajectory. 13:27.650 --> 13:34.400 And also in this case let's set the controllers as an empty array in order to use the default controllers. 13:34.600 --> 13:35.740 otherwise. 13:36.430 --> 13:39.430 So if one of the two planners failed. 13:39.430 --> 13:45.250 So it means that we weren't able to calculate a path from the current state to the goal state. 13:45.250 --> 13:49.570 And this, for example, can be due to the fact that the goal state is invalid. 13:49.570 --> 13:56.080 So imagine if here we put an angle that is bigger than 90 degrees, so bigger than the mechanical limits 13:56.080 --> 13:56.890 of the joints. 13:56.890 --> 13:59.680 So of course this position is not reachable. 13:59.680 --> 14:02.560 And so the planner will fail in this case. 14:02.560 --> 14:05.890 Here we want to print an error message in the terminal. 14:06.040 --> 14:15.550 So we can actually import from the RCL by logging the get logger function. 14:15.550 --> 14:16.030 Perfect. 14:16.030 --> 14:19.900 And so we can use this function here in the else statement. 14:19.900 --> 14:24.820 So let's get the logger and let's get the RCL pi logger. 14:24.820 --> 14:36.920 In order to print an error message that says here one or more planners failed perfect just to inform 14:36.920 --> 14:40.550 the user that the goal state was not valid. 14:41.330 --> 14:43.040 So we can save this script. 14:43.040 --> 14:49.400 And with this our move robot function is completed and so we are ready to start it. 14:49.400 --> 14:50.900 So we are ready to execute it. 14:50.900 --> 14:54.980 But in order to do so we are going to need a new launch file. 14:54.980 --> 15:00.020 So we are going to create a new launch file that actually starts this node here. 15:00.020 --> 15:04.700 So let's do it again here within the Arduino bot Pi examples package. 15:04.700 --> 15:11.270 And as by Ros2 conventions, we need to create a new folder called launch. 15:11.270 --> 15:23.330 And within this folder we can create our launch file that we can call simple move it interface dot launch 15:23.750 --> 15:24.500 dot pi. 15:24.530 --> 15:25.250 Perfect. 15:25.250 --> 15:28.370 And here before starting this node here. 15:28.370 --> 15:33.190 So this Python node here the move it pi so the move it. 15:33.220 --> 15:37.090 API for Python needs a move it configuration. 15:37.090 --> 15:41.470 So basically they need a move it config builder. 15:41.470 --> 15:47.710 And if you remember we have already used the moved config builder class here in the Arduino bot. 15:47.740 --> 15:48.880 Move it launch file. 15:48.880 --> 15:55.330 So in this launch file here, if we open it on one side we can see that here we have already used this 15:55.330 --> 15:56.260 file here. 15:56.260 --> 15:57.850 So the move it config builder. 15:57.880 --> 16:00.310 Now also to start this one here. 16:00.310 --> 16:02.590 So also to start this note that we have just developed. 16:02.590 --> 16:05.680 We are going to need these same class here. 16:05.680 --> 16:07.570 So actually we can copy it. 16:07.570 --> 16:13.090 So we can copy all this function and we can paste it here. 16:13.720 --> 16:15.550 Also we can import. 16:16.150 --> 16:20.830 So here we can copy the include statement and we can paste it. 16:20.860 --> 16:21.700 Perfect. 16:21.790 --> 16:27.220 And now actually for our simple launch file we are not going to need these two arguments. 16:27.220 --> 16:30.510 We are just going to need the moved it configuration perfect. 16:30.690 --> 16:32.310 So we can close this one. 16:32.310 --> 16:38.760 And here in this case the move it configuration basically is loading from the Arduino bot. 16:38.760 --> 16:39.180 Move it. 16:39.180 --> 16:45.780 And from the Arduino bot description all the Urdf model of the robot and also is loading all the configuration 16:45.780 --> 16:48.750 files that we have created for move it. 16:48.780 --> 16:49.620 Perfect. 16:49.620 --> 16:55.650 So to this configuration file, in order to use the Moovit API, we need to add another configuration 16:55.650 --> 16:57.360 so we can add it here. 16:57.360 --> 17:02.880 After the trajectory execution configuration and the configuration that we are going to need is the 17:02.880 --> 17:04.620 Moovit CP. 17:04.830 --> 17:08.850 In fact under the hood basically the Moovit pi. 17:08.880 --> 17:13.980 So this API here basically are just using the C plus plus API. 17:14.100 --> 17:16.770 So we need to configure this parameter here. 17:16.770 --> 17:22.560 So the Moovit cp with a new YAML file that you are going to create soon. 17:22.560 --> 17:27.820 And this YAML file that we are going to create will be at the file path. 17:27.850 --> 17:30.880 So still within the config folder. 17:30.880 --> 17:32.680 And we are going to create it soon. 17:32.680 --> 17:41.830 And we are going to call it planning Python API dot YAML. 17:41.830 --> 17:49.210 And so as you can understand from the name, this YAML file will be just used for the Python API. 17:49.240 --> 17:51.970 So to configure the Python API for move it. 17:52.300 --> 17:55.870 So with this we have just created a configuration file. 17:55.870 --> 18:00.190 So this one here an object of this type for our simple node. 18:00.190 --> 18:02.920 So for the simple move with interface node. 18:02.920 --> 18:05.740 So now we can actually start this node here. 18:05.860 --> 18:12.070 So the simple move it interface node. 18:12.190 --> 18:14.830 And so this is an instance of the node class. 18:14.830 --> 18:24.730 And we want to start from the package that is called Arduino board by examples. 18:24.730 --> 18:32.040 So from this package we want to start the executable that we have just created and it is called simple 18:32.310 --> 18:33.360 move it. 18:35.940 --> 18:37.020 Interface. 18:37.020 --> 18:45.510 So this script here that we have just created and we want to configure it with some parameters. 18:45.600 --> 18:46.170 Perfect. 18:46.170 --> 18:49.200 And the parameters that we want to configure here. 18:49.200 --> 18:50.310 So this is a list. 18:50.310 --> 18:53.610 And simply in this list we want to use this one here. 18:53.610 --> 18:56.850 So we want to use the move it config. 18:56.850 --> 19:01.860 And we want to this one to be converted into a dictionary. 19:01.860 --> 19:04.860 And apart from that we can also set the parameter. 19:05.190 --> 19:07.320 So here let's use the parentheses. 19:07.320 --> 19:08.670 And let's set the parameter. 19:08.670 --> 19:13.050 Use same time to true as. 19:13.050 --> 19:15.330 Basically we are going to use this node here. 19:15.330 --> 19:19.530 So the simple move interface just with the simulated robot. 19:19.560 --> 19:24.440 And so we can just hard code here the user same time to true. 19:24.530 --> 19:25.310 Perfect. 19:25.310 --> 19:32.540 So we are just missing now to return a launch description. 19:32.540 --> 19:34.910 And the constructor of this class takes a list. 19:34.910 --> 19:40.160 And within this list we need to insert all the nodes, all the actions that we want to execute with 19:40.160 --> 19:41.240 this launch file. 19:41.240 --> 19:45.740 And in this case this is just the simple move it interface. 19:45.740 --> 19:47.780 So only this one here. 19:47.960 --> 19:53.150 Also we can remove here all the classes that we are not using. 19:53.570 --> 19:58.430 Perfect in order to have a clearer file and also a smaller one. 19:58.430 --> 19:59.300 Perfect. 19:59.300 --> 20:04.670 And so with this one we have finally started our node and we have also configured it. 20:04.670 --> 20:09.620 And now we are just missing one last step that is this one here. 20:09.620 --> 20:13.340 So we want to create this configuration file here. 20:13.340 --> 20:15.830 So the planning Python API dot YAML. 20:15.830 --> 20:21.690 That is a configuration file that is only used in order to configure the Python API. 20:21.750 --> 20:27.030 So let's create it here within the Arduino bot move it package in the config folder. 20:27.030 --> 20:33.870 So as we have said here and let's call this one as we have set this one here so we can copy the name. 20:34.050 --> 20:39.390 And here let's create a new file and let's paste the name that we have inserted here. 20:39.390 --> 20:41.130 So let's press enter. 20:41.340 --> 20:50.010 And now in this file we just need to configure the planning pipelines that we want to use. 20:50.010 --> 20:56.280 And actually the pipeline names. 20:56.280 --> 21:01.080 So this is a vector containing all the planners that we want to use. 21:01.080 --> 21:05.520 So for the moment we are fine just with Ompl. 21:05.550 --> 21:09.390 So this is the only planner that we are going to use for this course. 21:09.420 --> 21:22.400 Then let's also configure here the plan request params and let's set the parameter planar id. 21:22.400 --> 21:26.540 And again we are only going to use om pl as a planar. 21:26.570 --> 21:32.810 Then let's also set the parameter planning attempts. 21:32.810 --> 21:35.330 And let's set this 1 to 1. 21:35.330 --> 21:38.870 And then the planning. 21:41.000 --> 21:42.050 Pipeline. 21:42.410 --> 21:44.390 And this is again om PL. 21:44.420 --> 21:46.520 So just the Ompl planner. 21:46.550 --> 21:57.980 And then also we can set the max velocity scaling factor so we can set this 1 to 1. 21:57.980 --> 22:01.220 So basically we are not scaling the maximum velocity. 22:01.220 --> 22:04.100 And also we can set the max. 22:06.530 --> 22:10.580 Acceleration scaling factor again to 1.0. 22:10.580 --> 22:17.090 And these actually are the only parameters that we need in order to configure the Python interface. 22:17.090 --> 22:19.320 So in order to configure the Python API. 22:19.350 --> 22:21.180 So let's save also this file. 22:21.180 --> 22:24.330 And now we are just missing to install everything. 22:24.330 --> 22:26.490 So to install this script here. 22:26.490 --> 22:30.900 So the simple movie interface within the Arduino Pi examples package. 22:30.900 --> 22:34.560 And also to install the launch file that we have just created. 22:34.650 --> 22:40.110 So we need to open the file setup.py that is in the Arduino dot pi examples. 22:40.110 --> 22:45.090 And in order to install our node we can just copy this line here. 22:45.090 --> 22:51.780 So the one that we have used for the Simple Action client and we can paste it here in order to install 22:51.780 --> 22:57.570 the simple move it interface node. 22:57.720 --> 23:02.100 And this node here is in the Arduino dot Pi examples folder. 23:02.100 --> 23:04.710 And it's called Simple Movie Interface. 23:04.710 --> 23:09.360 And still from this script here we want to execute the main function. 23:09.600 --> 23:12.150 Then we also need to install the launch folder. 23:12.150 --> 23:13.560 So this one here. 23:13.560 --> 23:18.050 And in order to install the launch folder we need to modify this section here. 23:18.050 --> 23:20.150 So the data files section. 23:20.300 --> 23:25.670 So let's import some useful libraries that are the OS Python library. 23:25.670 --> 23:32.840 And also from the glob library lets import the glob function. 23:32.870 --> 23:33.560 Perfect. 23:33.560 --> 23:37.040 And so now here so after the installation. 23:37.040 --> 23:42.470 So as you can see here this instruction here will install the file package dot XML. 23:42.470 --> 23:44.930 Now we also want to install the launch folder. 23:44.930 --> 23:47.240 So here let's add a new instruction. 23:47.240 --> 23:52.610 And from the US path join perfect. 23:52.640 --> 24:02.240 And here from the share folder and from the package name variable, we want to install the launch folder 24:02.240 --> 24:03.410 that we have just created. 24:03.410 --> 24:04.100 Perfect. 24:04.130 --> 24:10.790 Now here after the parenthesis we can use the glob function. 24:11.300 --> 24:22.000 And again within this function we can use the OS path join in order to access the launch folder and 24:22.000 --> 24:23.020 from the launch folder. 24:23.020 --> 24:30.970 So from this folder we want to install everything that has the name launch and the extension. 24:30.970 --> 24:43.420 So here let's use the parentheses p x y and also the extension y m a and also all other extensions. 24:43.990 --> 24:44.680 Perfect. 24:44.680 --> 24:51.100 So we can save also this file in which we have installed our simple movie interface and in which we 24:51.100 --> 24:53.500 have also installed the launch directory. 24:53.500 --> 25:00.820 So the launch file here and now don't forget as a last step to modify also the package dot XML as we 25:00.850 --> 25:02.950 have introduced new dependencies. 25:03.100 --> 25:09.910 In fact, we have introduced an execution dependency from the Ros2 launch package as we have created 25:09.910 --> 25:18.140 a new launch file, and also we have a new execution dependency from the move it by package. 25:18.170 --> 25:24.290 Anyway, this dependency here is only needed if you are using a newer version of Ros2. 25:24.320 --> 25:33.050 So only if the condition is that your Ros distro. 25:33.050 --> 25:37.700 So the Ros distribution that you are using is bigger than or equal to iron. 25:37.700 --> 25:42.530 So for example, if you are using Ros two chassis you will have this package here. 25:42.530 --> 25:48.680 So this library here that is that is not available in older version of Ros two like for example anvil 25:48.710 --> 25:49.640 perfect. 25:49.640 --> 25:51.290 So let's save also this file. 25:51.290 --> 25:57.800 And in the following lesson after developing the same interface with the movie C plus plus API, we 25:57.830 --> 25:59.210 are going to start this node. 25:59.210 --> 26:05.150 And we are going to see how we can use it to plan a trajectory to the desired position of the robot 26:05.150 --> 26:08.690 that we have set here in this file here. 26:08.690 --> 26:10.100 So in these lines here.