ブラウザとのROSによる通信

# 1.はじめに

ブラウザとROSで通信する方法

# 2.環境

ros noetic 
ubuntu 20.04

# 3.準備

1.`rosbridge_server`のインストール

```
sudo apt-get install ros-noetic-rosbridge-server
```

2.ブラウザプログラムの準備

2.1 ブラウザ用ディレクトリ作成

```
mkdir webpages
cd webpages
```

2.2 ブラウザプログラム

`index.html`の作成し,`roslibjs/exmaple/simple.html`をコピーする.
(`roslibjs`のインポートパスは変更が必要)

https://github.com/RobotWebTools/roslibjs/blob/develop/examples/simple.html

```webpages/index.html
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />

<script type="text/javascript" src="http://static.robotwebtools.org/EventEmitter2/current/eventemitter2.min.js"></script>
<script type="text/javascript" src="http://static.robotwebtools.org/roslibjs/current/roslib.min.js"></script>

<script>
  // Connecting to ROS
  // -----------------
  var ros = new ROSLIB.Ros();

  // If there is an error on the backend, an 'error' emit will be emitted.
  ros.on('error', function(error) {
    document.getElementById('connecting').style.display = 'none';
    document.getElementById('connected').style.display = 'none';
    document.getElementById('closed').style.display = 'none';
    document.getElementById('error').style.display = 'inline';
    console.log(error);
  });

  // Find out exactly when we made a connection.
  ros.on('connection', function() {
    console.log('Connection made!');
    document.getElementById('connecting').style.display = 'none';
    document.getElementById('error').style.display = 'none';
    document.getElementById('closed').style.display = 'none';
    document.getElementById('connected').style.display = 'inline';
  });

  ros.on('close', function() {
    console.log('Connection closed.');
    document.getElementById('connecting').style.display = 'none';
    document.getElementById('connected').style.display = 'none';
    document.getElementById('closed').style.display = 'inline';
  });

  // Create a connection to the rosbridge WebSocket server.
  ros.connect('ws://localhost:9090');

  // Publishing a Topic
  // ------------------

  // First, we create a Topic object with details of the topic's name and message type.
  var cmdVel = new ROSLIB.Topic({
    ros : ros,
    name : '/cmd_vel',
    messageType : 'geometry_msgs/Twist'
  });

  // Then we create the payload to be published. The object we pass in to ros.Message matches the
  // fields defined in the geometry_msgs/Twist.msg definition.
  var twist = new ROSLIB.Message({
    linear : {
      x : 0.1,
      y : 0.2,
      z : 0.3
    },
    angular : {
      x : -0.1,
      y : -0.2,
      z : -0.3
    }
  });

  // And finally, publish.
  cmdVel.publish(twist);

  //Subscribing to a Topic
  //----------------------

  // Like when publishing a topic, we first create a Topic object with details of the topic's name
  // and message type. Note that we can call publish or subscribe on the same topic object.
  var listener = new ROSLIB.Topic({
    ros : ros,
    name : '/listener',
    messageType : 'std_msgs/String'
  });

  // Then we add a callback to be called every time a message is published on this topic.
  listener.subscribe(function(message) {
    console.log('Received message on ' + listener.name + ': ' + message.data);

    // If desired, we can unsubscribe from the topic as well.
    listener.unsubscribe();
  });

  // Calling a service
  // -----------------

  // First, we create a Service client with details of the service's name and service type.
  var addTwoIntsClient = new ROSLIB.Service({
    ros : ros,
    name : '/add_two_ints',
    serviceType : 'rospy_tutorials/AddTwoInts'
  });

  // Then we create a Service Request. The object we pass in to ROSLIB.ServiceRequest matches the
  // fields defined in the rospy_tutorials AddTwoInts.srv file.
  var request = new ROSLIB.ServiceRequest({
    a : 1,
    b : 2
  });

  // Finally, we call the /add_two_ints service and get back the results in the callback. The result
  // is a ROSLIB.ServiceResponse object.
  addTwoIntsClient.callService(request, function(result) {
    console.log('Result for service call on ' + addTwoIntsClient.name + ': ' + result.sum);
  });

  // Advertising a Service
  // ---------------------

  // The Service object does double duty for both calling and advertising services
  var setBoolServer = new ROSLIB.Service({
    ros : ros,
    name : '/set_bool',
    serviceType : 'std_srvs/SetBool'
  });

  // Use the advertise() method to indicate that we want to provide this service
  setBoolServer.advertise(function(request, response) {
    console.log('Received service request on ' + setBoolServer.name + ': ' + request.data);
    response['success'] = true;
    response['message'] = 'Set successfully';
    return true;
  });

  // Setting a param value
  // ---------------------

  ros.getParams(function(params) {
    console.log(params);
  });

  // First, we create a Param object with the name of the param.
  var maxVelX = new ROSLIB.Param({
    ros : ros,
    name : 'max_vel_y'
  });

  //Then we set the value of the param, which is sent to the ROS Parameter Server.
  maxVelX.set(0.8);
  maxVelX.get(function(value) {
    console.log('MAX VAL: ' + value);
  });

  // Getting a param value
  // ---------------------

  var favoriteColor = new ROSLIB.Param({
    ros : ros,
    name : 'favorite_color'
  });

  favoriteColor.set('red');
  favoriteColor.get(function(value) {
    console.log('My robot\'s favorite color is ' + value);
  });
</script>
</head>

<body>
  <h1>Simple roslib Example</h1>
  <p>Run the following commands in the terminal then refresh this page. Check the JavaScript
    console for the output.</p>
  <ol>
    <li><tt>roscore</tt></li>
    <li><tt>rostopic pub /listener std_msgs/String "Hello, World"</tt></li>
    <li><tt>rostopic echo /cmd_vel</tt></li>
    <li><tt>rosrun rospy_tutorials add_two_ints_server</tt></li>
    <li><tt>roslaunch rosbridge_server rosbridge_websocket.launch</tt></li>
  </ol>
  <div id="statusIndicator">
    <p id="connecting">
      Connecting to rosbridge...
    </p>
    <p id="connected" style="color:#00D600; display:none">
      Connected
    </p>
    <p id="error" style="color:#FF0000; display:none">
      Error in the backend!
    </p>
    <p id="closed" style="display:none">
      Connection closed.
    </p>
  </div>
</body>
</html>

```

※ プログラムのROSインタフェースまとめ

*** 
Topic Pub: `/cmd_vel`(`geometry_msgs/Twist`)
Topic Sub: `/listener`(`std_msgs/String`)

Service Advertise: `/set_bool`(`std_srvs/SetBool`)
Service Call:  `/add_two_ints`(`rospy_tutorials/AddTwoInts`)

Set Param: `max_vel_y`
Get Param: `favorite_color`
***

# 4.実行


1.rosbridge_server起動

```
roslaunch rosbridge_server rosbridge_websocket.launch
```

2.ブラウザプログラム起動

```
cd webpages
python3 -m http.esrver
```

3.ブラウザ起動

http://0.0.0.0:8000/ にアクセス


# 5.ブラウザ-ROSの疎通確認
## 5.1 Publisher

1.topic受信コマンド実行

```
rostopic echo /cmd_vel
```

2.ブラウザをリロード

※値がechoされる

## 5.2 Subscriber

1.ブラウザのデバッグコンソールを開く
2.ブラウザにパブリッシュ

```
rostopic pub /listener std_msgs/String "data: 'aaaaa'"
```

※コンソールで送られた値を見れる

## 5.3 Service Server

1.ブラウザのデバッグコンソールを開く
2.サービスコールを実行

```
rosservice call /set_bool "data: false"
```

※コンソールで送られた値を見れる

## 5.4 Service Client
1.サーバープログラムインストール

```
sudo apt install ros-noetic-rospy-tutorials
```

2.サーバーを起動

```
rosrun rospy_tutorials add_two_ints_server
```

3.ブラウザリロード

※サーバープログラムが値を受信したのを確認できる
※`rossrv show rospy_tutorials/AddTwoInts`で見つからない場合ブラウザプログラムもこの型を使えないのでインストールする

# 6.参考

- ROS画像をブラウザに送信

https://qiita.com/hoshianaaa/items/c14827fd6a40edf53d85

- roslibjsまとめ(roslibjsでrosserviceをwaitする方法も乗っている)

https://qiita.com/daigakupotato/items/bb44c070d4304caa4bf1

# sample 

## topic pub only

```html
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />

<script type="text/javascript" src="http://static.robotwebtools.org/EventEmitter2/current/eventemitter2.min.js"></script>
<script type="text/javascript" src="http://static.robotwebtools.org/roslibjs/current/roslib.min.js"></script>

<script>

  var ros = new ROSLIB.Ros();

  ros.on('error', function(error) {
    document.getElementById('connecting').style.display = 'none';
    document.getElementById('connected').style.display = 'none';
    document.getElementById('closed').style.display = 'none';
    document.getElementById('error').style.display = 'inline';
    console.log(error);
  });

  ros.on('connection', function() {
    console.log('Connection made!');
    document.getElementById('connecting').style.display = 'none';
    document.getElementById('error').style.display = 'none';
    document.getElementById('closed').style.display = 'none';
    document.getElementById('connected').style.display = 'inline';
  });

  ros.on('close', function() {
    console.log('Connection closed.');
    document.getElementById('connecting').style.display = 'none';
    document.getElementById('connected').style.display = 'none';
    document.getElementById('closed').style.display = 'inline';
  });

  ros.connect('ws://localhost:9090');

  var cmdVel = new ROSLIB.Topic({
    ros : ros,
    name : '/cmd_vel',
    messageType : 'geometry_msgs/Twist'
  });

  var twist = new ROSLIB.Message({
    linear : {
      x : 0.1,
      y : 0.2,
      z : 0.3
    },
    angular : {
      x : -0.1,
      y : -0.2,
      z : -0.3
    }
  });

  cmdVel.publish(twist);

</script>
</head>

<body>
  <h1>ROS Topic Publish Example</h1>
  <div id="statusIndicator">
    <p id="connecting">
      Connecting to rosbridge...
    </p>
    <p id="connected" style="color:#00D600; display:none">
      Connected
    </p>
    <p id="error" style="color:#FF0000; display:none">
      Error in the backend!
    </p>
    <p id="closed" style="display:none">
      Connection closed.
    </p>
  </div>

</body>
</html>
```

- test

以下実行した状態で,ブラウザのリロード
```
rostopic echo /cmd_vel
```

## topic sub only

```html
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />

<script type="text/javascript" src="http://static.robotwebtools.org/EventEmitter2/current/eventemitter2.min.js"></script>
<script type="text/javascript" src="http://static.robotwebtools.org/roslibjs/current/roslib.min.js"></script>

<script>
  // Connecting to ROS
  // -----------------
  var ros = new ROSLIB.Ros();

  // If there is an error on the backend, an 'error' emit will be emitted.
  ros.on('error', function(error) {
    document.getElementById('connecting').style.display = 'none';
    document.getElementById('connected').style.display = 'none';
    document.getElementById('closed').style.display = 'none';
    document.getElementById('error').style.display = 'inline';
    console.log(error);
  });

  // Find out exactly when we made a connection.
  ros.on('connection', function() {
    console.log('Connection made!');
    document.getElementById('connecting').style.display = 'none';
    document.getElementById('error').style.display = 'none';
    document.getElementById('closed').style.display = 'none';
    document.getElementById('connected').style.display = 'inline';
  });

  ros.on('close', function() {
    console.log('Connection closed.');
    document.getElementById('connecting').style.display = 'none';
    document.getElementById('connected').style.display = 'none';
    document.getElementById('closed').style.display = 'inline';
  });

  // Create a connection to the rosbridge WebSocket server.
  ros.connect('ws://localhost:9090');

  //Subscribing to a Topic
  //----------------------

  // Like when publishing a topic, we first create a Topic object with details of the topic's name
  // and message type. Note that we can call publish or subscribe on the same topic object.
  var listener = new ROSLIB.Topic({
    ros : ros,
    name : '/listener',
    messageType : 'std_msgs/String'
  });

  // Then we add a callback to be called every time a message is published on this topic.
  listener.subscribe(function(message) {
    console.log('Received message on ' + listener.name + ': ' + message.data);

    // If desired, we can unsubscribe from the topic as well.
    listener.unsubscribe();
  });

</script>
</head>

<body>
  <h1>ROS Topic Subscribe Example</h1>
  <div id="statusIndicator">
    <p id="connecting">
      Connecting to rosbridge...
    </p>
    <p id="connected" style="color:#00D600; display:none">
      Connected
    </p>
    <p id="error" style="color:#FF0000; display:none">
      Error in the backend!
    </p>
    <p id="closed" style="display:none">
      Connection closed.
    </p>
  </div>
</body>
</html>
```

- test

```
rostopic pub /listener std_msgs/String "data: 'aaa'" 
```
ブラウザのconsole.logを確認して,メッセージがあればok