1 00:00:00,870 --> 00:00:03,380 Welcome to the Robotics Simulation project. 2 00:00:03,390 --> 00:00:06,270 It's time to sum up everything we've learned in this section. 3 00:00:06,300 --> 00:00:11,820 Now, I hope you have a good memory because the robot we are creating in this project is the example 4 00:00:11,820 --> 00:00:16,530 robot I used in my animations to help you understand what Ros is. 5 00:00:16,800 --> 00:00:23,520 The robot had a rectangular base with four wheels and a rod which protruded upward to hold up a camera. 6 00:00:23,550 --> 00:00:29,040 So in this project you are tasked with recreating this robot in a simulation so that you can drive it 7 00:00:29,040 --> 00:00:33,960 around the virtual environment and look at images coming in from the camera. 8 00:00:34,320 --> 00:00:40,020 Your final result should be a single launch file, which, when launched, will open up Ignition gazebo 9 00:00:40,020 --> 00:00:43,950 with this robot model, which you can then control over Ros. 10 00:00:44,400 --> 00:00:46,050 Let's break down this project. 11 00:00:47,650 --> 00:00:52,150 In this project, you will be creating a world and model SDF files. 12 00:00:52,240 --> 00:00:58,030 This model PSD file will contain everything needed to create the robot for this project, which is the 13 00:00:58,030 --> 00:00:59,710 wheeled robot with a camera. 14 00:01:00,250 --> 00:01:05,020 Remember that you can create the general model of the robot within Gazebo Classics Model Editor. 15 00:01:05,630 --> 00:01:11,990 Now your file should be configured such that the camera is a sensor which can transmit an image stream 16 00:01:11,990 --> 00:01:17,270 and that we are able to control the wheels of the robot so we can drive it around within the simulation. 17 00:01:17,940 --> 00:01:23,250 Then of course, you should create a launch file which starts up the ignition simulation with your world 18 00:01:23,250 --> 00:01:30,720 SDF file and then bridges the topics between ignition and Ros, too, so we can control the simulation 19 00:01:30,720 --> 00:01:31,740 over Ros. 20 00:01:32,350 --> 00:01:38,530 So essentially, when you run your launch file in terminal, you should see the simulation open up with 21 00:01:38,530 --> 00:01:40,420 your world and robot model. 22 00:01:40,570 --> 00:01:46,840 We then should be able to interact with it over ROS so we can create our ROS nodes or use tools like 23 00:01:46,850 --> 00:01:51,760 RCT to easily control the robot and process the image data. 24 00:01:53,800 --> 00:01:54,160 All right. 25 00:01:54,160 --> 00:01:55,810 This project is going to take some time. 26 00:01:55,840 --> 00:02:01,120 Simulations are complex and tedious, so don't get impatient with yourself if it feels like it's taken 27 00:02:01,120 --> 00:02:01,840 a while. 28 00:02:01,930 --> 00:02:02,560 Of course. 29 00:02:02,560 --> 00:02:07,930 Be sure to leverage all the code we've created in the previous lectures as we've created all the functionality 30 00:02:07,930 --> 00:02:11,020 needed for this project in chunks throughout this course. 31 00:02:11,290 --> 00:02:14,980 And feel free to rewatch some of those lectures if you are feeling lost. 32 00:02:15,400 --> 00:02:17,830 But with that, give this project a go. 33 00:02:26,620 --> 00:02:27,040 All right. 34 00:02:27,040 --> 00:02:27,790 How'd it go? 35 00:02:27,940 --> 00:02:33,040 Hopefully it was exciting to create a robot, which you could interact with in your simulation, which 36 00:02:33,040 --> 00:02:38,080 also sent back simulated data from the simulation as if it was a real robot. 37 00:02:38,380 --> 00:02:41,800 I'm going to go ahead and show you my approach in this walkthrough. 38 00:02:43,370 --> 00:02:46,610 So the first thing I need to do is create the robot model. 39 00:02:46,610 --> 00:02:49,880 So I will do this in Gazebo Classics Model editor. 40 00:02:53,560 --> 00:03:01,000 Once here I will create the chassis, which will be a cube that I will size to be x equals 1y0 point 41 00:03:01,000 --> 00:03:06,670 5z0 .25 metres and I'll place it near the origin like so. 42 00:03:16,780 --> 00:03:19,000 Then I'll go ahead and create my wheel. 43 00:03:47,820 --> 00:03:51,360 Which I can then duplicate to include each side. 44 00:04:24,340 --> 00:04:29,800 Now when I do my control for the wheels, rather than having two sets of driving wheels, I'm just going 45 00:04:29,800 --> 00:04:34,060 to have the front wheels be the ones which drive around. 46 00:04:34,090 --> 00:04:40,540 This means I should reduce the friction on the back wheels so that my robot can easily make turns. 47 00:04:40,540 --> 00:04:46,000 So I can do that by going into the back wheels, link descriptions and the collision model and setting 48 00:04:46,000 --> 00:04:50,410 mu one and mu two of the wheels 2.1. 49 00:04:53,370 --> 00:04:56,220 Then I will make the rod which holds the camera. 50 00:05:25,490 --> 00:05:30,680 Now I will make the box which goes on top of the rod that acts as the camera. 51 00:05:30,710 --> 00:05:33,320 It is worth noting by default, the camera plugin. 52 00:05:33,320 --> 00:05:39,590 I will be using faces towards the positive x axis, so I'll need to make sure the x axis of the cube 53 00:05:39,590 --> 00:05:41,840 faces towards the front of my robot. 54 00:05:57,550 --> 00:05:59,020 And now it's time for the joints. 55 00:05:59,020 --> 00:06:06,900 I will join together my front wheels first and go from left to right and choose the Z joint access. 56 00:06:06,910 --> 00:06:13,000 I could set the back wheels as fix since I lowered their friction and they will just be sliding on the 57 00:06:13,000 --> 00:06:13,540 ground. 58 00:06:13,540 --> 00:06:19,150 But I will leave them as resolute in case I want to change how I control this robot later in the future. 59 00:06:28,750 --> 00:06:30,490 Now I will join the camera. 60 00:06:30,490 --> 00:06:32,020 Rhod, to the base. 61 00:06:36,450 --> 00:06:42,900 And last but not least, I'll need to join this camera box to the camera rod as a fixed joint. 62 00:06:48,100 --> 00:06:51,460 With that out of the way, I can go ahead and save my model. 63 00:06:54,120 --> 00:06:59,070 I'll go ahead and save it as project robot model and exit the model editor. 64 00:07:03,250 --> 00:07:05,770 This will save the model in our home directory. 65 00:07:05,770 --> 00:07:12,820 So in the model editor models folder and here we have the project robot model that we just created with 66 00:07:12,820 --> 00:07:15,940 our corresponding model that SDF and config file. 67 00:07:16,030 --> 00:07:24,190 So I'm just going to go ahead and open up another tab and throw this into our package models folder. 68 00:07:28,740 --> 00:07:33,270 So now let's go ahead and continue editing this model within VTS code. 69 00:07:33,810 --> 00:07:40,470 So here under models, I have my project robot model, so we'll open up the model SDF file for it. 70 00:07:40,470 --> 00:07:46,980 And just a reminder that if you're getting this red text, you can instead set the HTML to XML syntax 71 00:07:46,980 --> 00:07:49,110 and that will fix it accordingly. 72 00:07:49,200 --> 00:07:55,410 For clarity sake, I'll rename link zero to chassis link, rename my wheels and joints so I know where 73 00:07:55,410 --> 00:08:00,960 they are on my robot chassis as well as name my camera rod link and camera link. 74 00:08:46,920 --> 00:08:51,390 So with the link renaming out of the way, I can go ahead and copy and configure the diff drive plugin 75 00:08:51,390 --> 00:08:54,630 from our wheeled model model on file. 76 00:08:54,630 --> 00:09:02,130 So here at the bottom of our model we had the diff drive plug in configuring our left and right wheel 77 00:09:02,130 --> 00:09:02,550 joints. 78 00:09:02,550 --> 00:09:04,380 So I'll just go ahead and copy that. 79 00:09:08,340 --> 00:09:11,790 And we will place it near the end of our robot model. 80 00:09:13,990 --> 00:09:17,350 And now I'll go ahead and rename these joints. 81 00:09:51,410 --> 00:09:51,540 Yeah. 82 00:10:06,510 --> 00:10:15,410 And for this case, I believe my wheel separation was 0.62 and my wheel radius was 0.25. 83 00:10:15,420 --> 00:10:21,360 And I'll go ahead and configure the topic to just be command velocity by default. 84 00:10:25,900 --> 00:10:31,770 Then I can go ahead and copy the camera plugin contents from our test world that we had done earlier. 85 00:10:34,140 --> 00:10:37,520 So here we have these sensor tags configuring our camera. 86 00:10:37,530 --> 00:10:44,610 So I'll just go ahead and copy this and place this within our camera link model. 87 00:10:46,920 --> 00:10:47,850 Which is right here. 88 00:10:47,850 --> 00:10:51,000 So I'll go ahead and plug this at the end of this link. 89 00:10:55,290 --> 00:10:55,650 All right. 90 00:10:55,650 --> 00:10:56,250 That should be good. 91 00:10:56,250 --> 00:11:01,560 Let's go ahead and save this and create a world file for this simulation. 92 00:11:01,950 --> 00:11:07,310 So I'll go ahead and call this simulation project World SDF. 93 00:11:10,220 --> 00:11:16,580 And I'll take our wheeled model world from earlier in the section and paste the contents here. 94 00:11:16,580 --> 00:11:23,660 And instead of including our wheeled model, we will be including our project robot model, which should 95 00:11:23,660 --> 00:11:28,020 match the name of this particular folder within our model's directory and our robots. 96 00:11:28,040 --> 00:11:33,230 A little bit shorter this time, so I'll set the post to 0.4 offset off the z axis. 97 00:11:33,380 --> 00:11:36,620 All right, let's save this file and test to see what we have so far. 98 00:11:36,710 --> 00:11:40,250 So go ahead and rebuild our workspace to include these new models. 99 00:11:44,220 --> 00:11:44,910 All right. 100 00:11:46,810 --> 00:11:51,370 Now I can go back to terminal and be sure to source my models directory. 101 00:11:59,530 --> 00:12:04,540 Then I can go ahead and launch the ignition gazebo simulation with this project world. 102 00:12:12,120 --> 00:12:12,450 All right. 103 00:12:12,450 --> 00:12:13,320 So let's go ahead and open. 104 00:12:13,320 --> 00:12:21,540 Then we can see our wheeled project model here on our blue ground plane, and then I can go ahead and 105 00:12:21,540 --> 00:12:23,970 double check that features like our camera are working. 106 00:12:23,970 --> 00:12:27,000 So go ahead and check the topics that are in ignition. 107 00:12:28,650 --> 00:12:35,520 And again, if you ever needed more information about a topic, you can do again, topic, info, topic 108 00:12:35,520 --> 00:12:38,010 and the name of the particular topic. 109 00:12:38,610 --> 00:12:45,030 So in this case, my camera ignition topic has a message type of ignition dot messages dot image which 110 00:12:45,030 --> 00:12:49,130 may be useful for us in a bit when we go to create our launch file. 111 00:12:49,140 --> 00:12:54,990 So let's go ahead and make that so that we can run this simulation using a single launch file instead 112 00:12:54,990 --> 00:13:02,220 of having to export our model environment and launch our simulation and any other nodes from scratch. 113 00:13:03,090 --> 00:13:10,260 So I'll create a new launch file and I'll just call this simulation underscore project launch dot pie, 114 00:13:11,850 --> 00:13:16,560 and we can just copy over our simulation launch file we made in the previous lecture. 115 00:13:18,040 --> 00:13:22,480 With the only difference being we all need to change the path of our world file. 116 00:13:22,480 --> 00:13:26,080 In this case, we're using this simulation project world that SDF. 117 00:13:35,290 --> 00:13:40,060 And then scrolling down further, I had simplified the name of the topic. 118 00:13:41,230 --> 00:13:45,480 In our project robot model to instead be just command velocity. 119 00:13:45,490 --> 00:13:46,870 So if I scroll all the way down. 120 00:13:47,710 --> 00:13:50,860 We see I changed the mapping to just be command. 121 00:13:50,860 --> 00:13:55,300 Vell, instead of that model's wheeled model type of format. 122 00:13:55,960 --> 00:13:57,850 So I actually don't need to do the remapping here. 123 00:13:57,850 --> 00:14:03,370 Instead, I do have to change the arguments here, so the ignition topic name should now be just command 124 00:14:03,370 --> 00:14:04,000 Vel. 125 00:14:04,870 --> 00:14:07,600 And then we don't need to remap anything here. 126 00:14:07,600 --> 00:14:09,730 So I'll just go ahead and delete those lines for now. 127 00:14:09,970 --> 00:14:13,470 But I will have to map my camera as well. 128 00:14:13,480 --> 00:14:16,600 So to do that, I'll simply add another entry to this list. 129 00:14:24,280 --> 00:14:24,640 All right. 130 00:14:24,640 --> 00:14:30,850 So again, this time we're taking the sensor messages image Ros message type, and we're bridging it 131 00:14:30,850 --> 00:14:38,110 from the ignition messages, image message type, which we saw was the message type of our particular 132 00:14:38,110 --> 00:14:39,550 camera topic here. 133 00:14:40,840 --> 00:14:44,260 And actually I will include the remapping argument for right now. 134 00:14:47,820 --> 00:14:53,460 And for this case, I'm actually going to remap the camera topic to match something more suitable towards 135 00:14:53,460 --> 00:14:58,860 what you would see in Ross, which would generally be camera slash, image underscore, raw to know 136 00:14:58,860 --> 00:15:02,820 that this should be the topic which the raw images are coming over. 137 00:15:03,150 --> 00:15:07,920 And of course, if I wanted to, I could have instead change the topic name within our model PSD file 138 00:15:07,920 --> 00:15:10,890 when we were working with our camera joint. 139 00:15:12,130 --> 00:15:16,450 So I could have changed the topic name here, but I'll just keep this in for now so that we have an 140 00:15:16,450 --> 00:15:21,130 example of remapping topics within this example launch file. 141 00:15:21,130 --> 00:15:26,080 So I'll go ahead and save this and rebuild it so that this new launch file gets included. 142 00:15:26,950 --> 00:15:27,610 All righty. 143 00:15:27,790 --> 00:15:30,400 So now let's run the simulation using the launch file. 144 00:15:31,510 --> 00:15:33,460 So I'll go ahead and clear some of these screens. 145 00:15:37,120 --> 00:15:39,400 Now, of course, first we have to source our workspace. 146 00:15:44,570 --> 00:15:47,240 And then run the simulation project launch file. 147 00:15:55,040 --> 00:15:55,340 All right. 148 00:15:55,340 --> 00:15:57,320 So this has gone ahead and started. 149 00:15:57,320 --> 00:16:01,640 And now if I go into my second window and do Ross two topic list. 150 00:16:03,430 --> 00:16:08,770 We will see our command velocity topic as well as the image raw camera stream coming out. 151 00:16:08,770 --> 00:16:11,950 So of course if we wanted to interact with this, I could open up our. 152 00:16:16,570 --> 00:16:19,660 And I'll keep this simulation window open here on the side. 153 00:16:24,610 --> 00:16:27,550 And I will open a new plugin for the image view. 154 00:16:30,540 --> 00:16:34,380 So here we can control the direction which our robot drives. 155 00:16:34,380 --> 00:16:38,220 And here we can see a camera view of what our robot is driving here. 156 00:16:38,220 --> 00:16:42,900 So I'll just add some things to our scene just to add a little bit of. 157 00:16:44,100 --> 00:16:46,200 Context as to where we are. 158 00:16:50,850 --> 00:16:56,820 And so now I can go ahead and drive around a bit and publish this by clicking the checkmark. 159 00:16:58,930 --> 00:17:00,370 Well, it's a bit too slow. 160 00:17:02,420 --> 00:17:03,830 And there we go. 161 00:17:03,830 --> 00:17:07,010 We now see our robot is turning slowly. 162 00:17:08,480 --> 00:17:15,830 Although notice this issue here where the robot chassis is spinning slowly, but our camera rod and 163 00:17:15,830 --> 00:17:19,550 camera link are actually keeping about the same position. 164 00:17:20,410 --> 00:17:25,990 So this is definitely a weird interaction that you probably weren't expecting, and this has to do with 165 00:17:25,990 --> 00:17:27,790 our physics simulation engine. 166 00:17:27,790 --> 00:17:33,310 So essentially this is a joint and we never really provided much friction elements for it or dampening. 167 00:17:33,310 --> 00:17:39,190 So it's just freely spinning around here, assuming that there is no type of normal friction or static 168 00:17:39,190 --> 00:17:42,750 connection like we might assume this robot might have. 169 00:17:42,760 --> 00:17:44,740 So I do want to keep this joint as a joint. 170 00:17:44,740 --> 00:17:46,810 I don't want to fix it and keep it static. 171 00:17:47,440 --> 00:17:52,930 So if I head back over to my Visual Studio code, I'll actually just search for damping. 172 00:17:54,430 --> 00:17:57,400 And here we see several of them pop up. 173 00:17:57,400 --> 00:18:00,160 And if we scroll down, we should find. 174 00:18:01,140 --> 00:18:08,190 Where our chassis connects to our camera rod link and I will just increase this dampening to something 175 00:18:08,220 --> 00:18:10,560 say along of 0.6. 176 00:18:11,100 --> 00:18:16,380 And of course you could set other dynamic settings such as the spring stiffness and you can even specify 177 00:18:16,380 --> 00:18:19,590 your coefficients of friction within the link itself. 178 00:18:19,590 --> 00:18:20,610 But this should do for now. 179 00:18:20,610 --> 00:18:22,740 So if I go ahead and save this. 180 00:18:25,580 --> 00:18:27,260 And we will close the simulation. 181 00:18:27,270 --> 00:18:32,240 And so the changes should have automatically taken effect since we've used Simulink install. 182 00:18:33,500 --> 00:18:35,780 So if I go ahead and rerun this. 183 00:18:38,630 --> 00:18:39,980 We're still publishing our message. 184 00:18:39,980 --> 00:18:46,310 So our robot begins spinning, but we see the camera head stays attached so I can put objects in my 185 00:18:46,310 --> 00:18:54,110 environment again, and we can see them in our field of view as the robot travels around. 186 00:18:59,860 --> 00:19:05,950 Oh, it does seem I made a mistake here in terms of which way is forward and which way is backwards. 187 00:19:06,520 --> 00:19:08,710 So I'll go ahead and fix that as well. 188 00:19:09,860 --> 00:19:15,680 So this most likely has to do with the fact that I switched the axis when I set my joints. 189 00:19:15,680 --> 00:19:18,290 I was supposed to set it to negative Z. 190 00:19:18,500 --> 00:19:21,130 But instead I had set it at positive Z. 191 00:19:21,140 --> 00:19:27,230 So if we actually look at the Axis for this joint, it says 001. 192 00:19:27,230 --> 00:19:32,810 And what I'm actually going to do here is set this to negative one for both the front left and front 193 00:19:32,810 --> 00:19:34,160 right wheel joint. 194 00:19:34,160 --> 00:19:39,380 So now if I go ahead and save this, we run our simulation. 195 00:19:43,700 --> 00:19:48,650 And now we're actually driving forward, as we expect that I'm turning a little bit here because I still 196 00:19:48,650 --> 00:19:52,400 have a Z attribute to our angular velocity. 197 00:19:59,810 --> 00:20:03,510 But here we see that our simulation is working properly. 198 00:20:03,530 --> 00:20:11,060 We have a world file which we built with our robot model that we created in Gazebo Classic and then 199 00:20:11,060 --> 00:20:13,820 placed into our ignition gazebo simulation. 200 00:20:13,850 --> 00:20:16,520 Now, I can actually take the simulation one step further. 201 00:20:16,520 --> 00:20:22,940 So remember, I created a joint here between our chassis and camera rod because I would be ideal if 202 00:20:22,940 --> 00:20:25,520 we could actually control this on our robot. 203 00:20:25,520 --> 00:20:28,880 So if we had a motorized base and the camera could turn. 204 00:20:28,880 --> 00:20:33,440 So let's take advantage of this joint using what's called the joint position controller. 205 00:20:33,440 --> 00:20:38,030 Joint controller plug ins are great as general purpose use cases to control your joints. 206 00:20:38,030 --> 00:20:44,600 Say if you had a motorized joint, we can get an example of this from the examples Ignition Gazebo provides. 207 00:20:44,600 --> 00:20:48,080 Specifically the joint position controller SDF file. 208 00:20:52,870 --> 00:20:56,650 You could check out this file in the simulation, but I think it will be easier just to show you how 209 00:20:56,650 --> 00:20:59,080 this plugin works in the context of this project. 210 00:20:59,470 --> 00:21:01,420 So I'm just going to head to the bottom of the file. 211 00:21:02,200 --> 00:21:05,910 And here we see a plugin before the closing model tag. 212 00:21:05,920 --> 00:21:12,460 The plugin takes in the joint, name a topic and then you can configure and put limits on a PID controller, 213 00:21:12,460 --> 00:21:17,950 which is a common controller in robots and automated machines to change the signal, which sends motion 214 00:21:17,950 --> 00:21:20,080 commands in a fluid controlled manner. 215 00:21:20,260 --> 00:21:27,310 For now, I'm just going to copy and paste it into my robot model SDF file after my drive, plug in 216 00:21:27,310 --> 00:21:31,330 and change the joint name, which in this case mines is camera rod joint. 217 00:21:31,570 --> 00:21:35,470 And I'll just change the topic name to camera rod, position command. 218 00:21:35,950 --> 00:21:38,290 And I'll just leave the PID values as is. 219 00:21:39,460 --> 00:21:45,370 And let me just confirm that this is indeed the joint name camera, joint. 220 00:21:45,370 --> 00:21:47,620 So let's go ahead back into our joints and check. 221 00:21:47,620 --> 00:21:52,030 So here is where the chassis connects to the camera rod link. 222 00:21:52,030 --> 00:21:57,910 So I will change this joint name to make more sense to camera rod joint. 223 00:22:01,200 --> 00:22:01,650 All righty. 224 00:22:01,650 --> 00:22:02,580 So that things match up. 225 00:22:02,580 --> 00:22:04,650 So I'll go ahead and save this file. 226 00:22:05,490 --> 00:22:11,910 And now we need to bridge this camera rod position command topic from ignition gazebo to Ros. 227 00:22:11,910 --> 00:22:14,120 So I'll add it to my launch file. 228 00:22:14,130 --> 00:22:18,150 If we actually go back to the joint position controller, SDF all the way at the top. 229 00:22:18,150 --> 00:22:22,560 It has instructions for us, so it tells us what gazebo message type this plugin uses, which in this 230 00:22:22,560 --> 00:22:24,000 case is double. 231 00:22:24,000 --> 00:22:29,790 Now Ros does not have a double message type, but the equivalent is a float 64 message type from the 232 00:22:29,790 --> 00:22:31,320 standard messages package. 233 00:22:32,190 --> 00:22:34,560 So I'll just go ahead and copy this. 234 00:22:36,840 --> 00:22:42,840 And then in our launch file, we'll add one more argument to our ignition bridge. 235 00:22:46,530 --> 00:22:53,940 So this is the ignition topic name I specified here in our model that file camera, rod, position, 236 00:22:53,940 --> 00:23:00,180 command, and then we're going to convert this over to standard messages. 237 00:23:00,180 --> 00:23:06,510 Float 64 from the ignition messages, double message type. 238 00:23:06,510 --> 00:23:10,950 With that, I can save these files and restart the simulation. 239 00:23:19,730 --> 00:23:20,020 All right. 240 00:23:20,020 --> 00:23:22,250 So that's gone ahead and opened as normal. 241 00:23:22,430 --> 00:23:27,890 So I'll go ahead and place some objects again, just to add some variety. 242 00:23:32,210 --> 00:23:34,490 And I will stop our robot from turning. 243 00:23:36,020 --> 00:23:38,330 All right, so we're faced this way towards the sphere. 244 00:23:38,600 --> 00:23:42,500 And now I can go ahead and refresh my topics. 245 00:23:42,890 --> 00:23:46,880 Go down and let me expand this a little bit so we can see better. 246 00:23:47,420 --> 00:23:50,660 And we are interested in this camera rod position topic. 247 00:23:56,330 --> 00:23:57,800 Whoops, I made a typo here. 248 00:23:57,800 --> 00:23:59,540 This should be camera position command. 249 00:24:03,580 --> 00:24:05,500 Let's go ahead and save that. 250 00:24:05,710 --> 00:24:07,030 Try this one more time. 251 00:24:21,650 --> 00:24:21,980 All right. 252 00:24:21,980 --> 00:24:26,810 So I've added those objects and now we can go camera rod, position, command. 253 00:24:28,180 --> 00:24:30,040 And I'll go ahead and add that. 254 00:24:31,390 --> 00:24:33,910 And we just have this simple data attribute. 255 00:24:34,390 --> 00:24:39,910 So if I set that to a particular position in Radiance, so let's say I want to turn 90 degrees, that 256 00:24:39,910 --> 00:24:42,730 would be about 1.57 radiance. 257 00:24:43,900 --> 00:24:52,640 So if I publish this, we see the camera goes and turns towards this elliptical figure here. 258 00:24:52,660 --> 00:24:57,520 And of course, we could change that to -1.57 radians and it'll turn. 259 00:24:59,180 --> 00:25:00,860 He'll turn out 90 degrees from the normal. 260 00:25:00,860 --> 00:25:03,380 So it turns around and we can see the ball. 261 00:25:03,380 --> 00:25:06,200 And of course, you can have different degree measurements here. 262 00:25:06,200 --> 00:25:11,480 So we can do about 45 degrees, which is about 0.78 radians. 263 00:25:13,780 --> 00:25:17,680 And we see here our sphere next to our cylinder. 264 00:25:17,710 --> 00:25:22,330 Now notice it kind of wobbles a bit back and forth whenever I change these values. 265 00:25:22,330 --> 00:25:26,830 And that just has to do with your PID controller and how it's trying to do the dampening. 266 00:25:26,830 --> 00:25:33,820 So you can always change the dampening in the joint as well as play with your ID values of your controller 267 00:25:33,820 --> 00:25:35,880 to smooth that out if you want it to. 268 00:25:35,890 --> 00:25:41,410 But with that we've successfully created a simulation of a robot which utilizes plug ins to command 269 00:25:41,410 --> 00:25:45,640 our robot and receive simulated sensor data over ROS. 270 00:25:46,450 --> 00:25:51,310 Well, hopefully you got similar results than I did and were able to successfully interact with your 271 00:25:51,310 --> 00:25:53,530 robot and ignition gazebo using Ros. 272 00:25:53,530 --> 00:25:57,520 So congratulations on applying what you've learned in this section. 273 00:25:57,760 --> 00:26:03,640 Now, this was a relatively simple simulation and our robot clearly doesn't have much purpose in the 274 00:26:03,650 --> 00:26:08,560 simulation or any other ROS nodes to give it a higher level of autonomy. 275 00:26:08,920 --> 00:26:13,240 Well, believe it or not, we've been creating a lot of functionality throughout this course which could 276 00:26:13,240 --> 00:26:16,030 be incorporated into this simulated robot. 277 00:26:16,420 --> 00:26:22,000 We created a publisher to simulate a wheel encoder so we could calculate the robot's speed. 278 00:26:22,270 --> 00:26:27,220 We created service requests to have the robot return a picture after turning its head by the requested 279 00:26:27,220 --> 00:26:33,850 amount of degrees, and we even implemented in action server to take in to navigate to a point of interest. 280 00:26:34,330 --> 00:26:38,860 Also, if you remember in the ROS Framework animation video, I also mentioned the wheeled robot had 281 00:26:38,860 --> 00:26:40,870 an IMU and Jeep's sensor. 282 00:26:40,870 --> 00:26:45,820 So how could implementing these sensors within simulation help you out with your navigation? 283 00:26:46,780 --> 00:26:52,960 So as an extra credit and a potential project to show off to job recruiters, I encourage you to create 284 00:26:52,960 --> 00:26:58,930 an entirely new ROS package which will contain all the files needed for a simulation environment similar 285 00:26:58,930 --> 00:27:05,830 to the one we just created, but with additional sensors and ROS nodes to help add to the robot's autonomous 286 00:27:05,830 --> 00:27:06,730 functionality. 287 00:27:07,180 --> 00:27:12,850 You could send commands through RCT or implement your own terminal command line interface to have the 288 00:27:12,850 --> 00:27:15,430 robot execute customizable routines. 289 00:27:15,880 --> 00:27:21,190 If you decide to go down this route, I encourage you to check for ROS packages the community has developed, 290 00:27:21,190 --> 00:27:27,760 which may help, such as the robot localization package for using sensor data to more accurately determine 291 00:27:27,760 --> 00:27:34,300 where your robot is, as well as the navigation to set of ROS to packages for implementing complex path 292 00:27:34,300 --> 00:27:35,530 planning features. 293 00:27:36,100 --> 00:27:41,020 Now that you know how to create simulations, it's time for you to really start putting your robotics 294 00:27:41,020 --> 00:27:47,110 problem solving skills to the test, leveraging what you've learned in this course and from the amazing 295 00:27:47,110 --> 00:27:48,280 ROS community. 296 00:27:48,490 --> 00:27:55,150 So try to challenge yourself and see just how complicated creating robust robotic software in realistic 297 00:27:55,150 --> 00:27:56,830 scenarios can be. 298 00:27:57,340 --> 00:27:58,090 Good luck.