应用程序的ROS//桌面版本运行良好，但在android上运行时，StatusStream总是返回Status.CLOSED。

Question

我在做一个远程操作应用程序。我使用roslib来实现ros功能，但Android上的连接存在问题。Snapshot.connectionState总是在等待，流状态在乞讨中从null变为Status.CLOSED。此外，Android会产生以下错误：

E/BpSurfaceComposerClient(15711)：处理失败(-1)

UPD:当我尝试使用ros = Ros(url: 'ws://10.0.2.15:9090');连接时，" connect“按钮改为”断开“，这意味着正确的连接，但是cmd_vel主题没有收到来自app的任何信息，因此机器人只是静止不动，而且，不能通过单击”断开“按钮来终止连接。

这是我的密码

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:roslib/roslib.dart';
import 'dart:convert';

class mainPage extends StatefulWidget {
  const mainPage({Key? key}) : super(key: key);

  @override
  State<mainPage> createState() => _mainPageState();
}

class _mainPageState extends State<mainPage> {
  int linearCounter = 0;
  int angularCounter = 0;
  late Ros ros;
  late Topic cmd_vel;
  late Topic image_raw;

  @override
  void initState() {
    ros = Ros(url: 'ws://10.0.2.15:9090');
    image_raw = Topic(
      ros: ros,
      name: '/camera/rgb/image_raw/compressed',
      type: "sensor_msgs/CompressedImage",
      reconnectOnClose: true,
      queueLength: 10,
      queueSize: 10,
    );
    cmd_vel = Topic(
      ros: ros,
      name: '/cmd_vel',
      type: "geometry_msgs/Twist",
      reconnectOnClose: true,
      queueLength: 10,
      queueSize: 10
    );
    super.initState();
  }

  void move(double coordinate, double angle) {
    double linearSpeed = 0.0;
    double angularSpeed = 0.0;
    linearSpeed = linearCounter * coordinate;
    angularSpeed = angularCounter * angle;
    publishCmd(linearSpeed, angularSpeed);
  }

  void initConnection() async {
    ros.connect();
    await image_raw.subscribe();
    await cmd_vel.advertise();
    setState(() {});
  }

  void destroyConnection() async {
    await image_raw.unsubscribe();
    await ros.close();
    setState(() {});
  }

  void publishCmd(double coord, double ang) async {
    var linear = {'x': coord, 'y': 0.0, 'z': 0.0};
    var angular = {'x': 0.0, 'y': 0.0, 'z': ang};
    var geomTwist = {'linear': linear, 'angular': angular};
    await cmd_vel.publish(geomTwist);
    if (kDebugMode) {
      print('cmd published');
    }
  }

  Widget getImage(String vid_snapshot) {
    const Base64Codec base64 = Base64Codec();
      return Flexible(
        flex: 1,
        child: Image.memory(
          base64.decode(vid_snapshot),
          gaplessPlayback: true,
          height: 400,
          fit: BoxFit.fill,
        ),
      );
  }

  @override
  Widget build(BuildContext context) {
    return StreamBuilder<Object>(
      stream: ros.statusStream,
      builder: (context, AsyncSnapshot<dynamic> snapshot) {
        return Scaffold(
          backgroundColor: Colors.grey[700],
          appBar: AppBar(
            title: const Text('Teleoperation app'),
            centerTitle: true
          ),
          body: SafeArea(
            minimum: const EdgeInsets.only(bottom: 30.0),
            child: Column(
              mainAxisAlignment: MainAxisAlignment.end,
              children: [
                Row(
                  mainAxisAlignment: MainAxisAlignment.center,
                  children: [
                    StreamBuilder(
                      stream: image_raw.subscription,
                      builder: (vidContext, AsyncSnapshot<dynamic> vidSnapshot) {
                        if (vidSnapshot.data == null) {
                          return const Text('No signal');
                        }
                        Map<String, dynamic> value = Map<String, dynamic>.from(vidSnapshot.data);
                        return getImage(value['msg']['data']);
                      },
                    ),
                  ],
                ),
                Padding(padding: EdgeInsets.only(bottom: 30.0)),
                Row(
                  mainAxisAlignment: MainAxisAlignment.center,
                  children: [
                    ActionChip(
                      label: Text(snapshot.data == Status.CONNECTED
                        ? 'DISCONNECT'
                        : 'CONNECT'),
                      backgroundColor: snapshot.data == Status.CONNECTED
                        ? Colors.green[300]
                        : Colors.grey[300],
                      onPressed: () {
                        print(snapshot.data);
                        if (snapshot.data != Status.CONNECTED) {
                          initConnection();
                        } else {
                          destroyConnection();
                        }
                      },
                    ),
                  ],
                ),
                Padding(padding: EdgeInsets.only(bottom: 15.0)),
                Row(
                  mainAxisAlignment: MainAxisAlignment.center,
                  children: [
                    ElevatedButton.icon(
                        style: ElevatedButton.styleFrom(
                          minimumSize: Size(130.0, 40.0),
                        ),
                        onPressed: () {
                          linearCounter++;
                          move(0.1, 0.0);
                        },
                        icon: Icon(Icons.arrow_upward),
                        label: Text('Forward')
                    ),
                  ],
                ),
                Padding(padding: EdgeInsets.only(bottom: 30.0)),
                Row(
                  mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                  children: [
                    ElevatedButton.icon(
                      style: ElevatedButton.styleFrom(
                        minimumSize: Size(130.0, 40.0),
                      ),
                      onPressed: () {
                        angularCounter++;
                        move(0.0, 0.1);
                      },
                      icon: Icon(Icons.arrow_back),
                      label: Text('Left')
                    ),
                    ElevatedButton.icon(
                      style: ElevatedButton.styleFrom(
                        minimumSize: Size(130.0, 40.0),
                      ),
                      onPressed: () {
                        angularCounter = 0;
                        linearCounter = 0;
                        move(0.0, 0.0);
                      },
                      icon: Icon(Icons.stop_circle_outlined),
                      label: Text('Stop')
                    ),
                    ElevatedButton.icon(
                      style: ElevatedButton.styleFrom(
                        minimumSize: Size(130.0, 40.0),
                      ),
                      onPressed: () {
                        angularCounter--;
                        move(0.0, 0.1);
                      },
                      icon: Icon(Icons.arrow_forward),
                      label: Text('Right')
                    ),
                  ],
                ),
                Padding(padding: EdgeInsets.only(bottom: 30.0)),
                Row(
                  mainAxisAlignment: MainAxisAlignment.center,
                  children: [
                    ElevatedButton.icon(
                      style: ElevatedButton.styleFrom(
                        minimumSize: Size(130.0, 40.0),
                      ),
                      onPressed: () {
                        linearCounter--;
                        move(0.1, 0.0);
                      },
                      icon: Icon(Icons.arrow_downward),
                      label: Text('Backward')
                    ),
                  ],
                ),
              ],
            ),
          ),
        );
      },
    );
  }
}

Answer 1

我设法解决了这个问题。您的电话和计算机应该连接到同一个Wi网络。在您的~/.bashrc文件中，应该添加两行：

export ROS_MASTER_URI=http://192.168.1.110:11311

export ROS_IP=192.168.1.110

192.168.1.110是网络中计算机的IP地址。

在您的应用程序中，将行ros = Ros(url: 'ws://10.0.2.15:9090');改为ros = Ros(url: 'ws://192.168.1.110:9090');

这就是解决办法。造成我的问题的主要原因是，我在虚拟机上做了所有的事情，并且不知道错误在哪里，即使虚拟机本身造成了一个错误。