ROS与DJI N3飞控建立连接并简单控制

平台： UBUNTU16.04
ROS kinetic
DJI ASSISTANT 2
OSDK3.3.1
Onboard SDK ROS 3.3.1
DJI N3飞控（型号：3.2.36.8 固件：1.7.1.5）
DJI LightBridge II

一、OSDK安装
参考：http://developer.dji.com/onboard-sdk/documentation/sample-doc/sample-setup.html#ros-oes
Installing the OSDK
1-Clone (or download as zip) the DJI OSDK from Github here.
https://github.com/dji-sdk/Onboard-SDK/releases
2-Open a terminal inside the onboardsdk folder and follow these steps to build the core OSDK library：

mkdir buildcd buildcmake ..make djiosdk-core

3-Now, install the osdk-core library to your system so that the dji_sdk ROS node may find it and link against it:

sudo make install djiosdk-core

Building the ROS Nodes
4-If you don’t have a catkin workspace, create one as follows:

mkdir catkin_wscd catkin_wsmkdir srccd srccatkin_init_workspace

5-Clone (or download as zip) the DJI OSDK-ROS from Github here in the src folder.
https://github.com/dji-sdk/Onboard-SDK-ROS/releases
6-Build the dji_sdk ROS package and the dji_sdk_demo ROS package.

cd ..catkin_make

Configuration
7-Remember to source your setup.bash:

source devel/setup.bash

8-Edit the launch file and enter your App ID, Key, Baudrate and Port name in the designated places:

rosed dji_sdk sdk.launch

Running the Samples
9-Start up the dji_sdk ROS node:

roslaunch dji_sdk sdk.launch

10-Open up another terminal and cd to your catkin_ws location, and start up a sample (e.g. flight control sample):

source devel/setup.bashrosrun dji_sdk_demo demo_flight_control

11-Follow the prompt on screen to choose an action for the drone to do.

二、注意事项

1- rosed dji_sdk sdk.launch配置文件;

<launch>    <node pkg="dji_sdk" type="dji_sdk_node" name="dji_sdk" output="screen">    <!-- node parameters -->    <param name="serial_name" type="string" value="/dev/ttyUSB1"/>    <param name="baud_rate" type="int" value="230400"/>    <param name="app_id" type="int" value="×××××××"/>    <param name="app_version" type="int" value="1"/>    <param name="align_time" type="bool" value="false"/>    <param name="enc_key" type="string" value="a2870084××××××26726e5413×××××××2099fd652××××××fac53581c1c392"/>    <param name="use_broadcast" type="bool" value="false"/>    </node></launch>

其中：

<param name="serial_name" type="string" value="/dev/ttyUSB1"/>

USB端口号可通过命令:

ls -l /dev | grep ttyUSB 

查看。

2- DJI ASSISITANT2 中SDK项设置波特率与配置文件一致（实际均为230400），勾选“使能API”；

DJI ASSISITANT2 中重新设置波特率后需要断电再上电重启一次N3控制器。

3- 使用命令

sudo chmod 666 /dev/ttyUSB0 

获取端口权限（USB端口号依据命令 ls -l /dev | grep ttyUSB查看）

4-使用命令 roslaunch dji_sdk sdk.launch 之前，DJI ASSISITANT 2 需连接N3，同时DJI LightBridge II 模式开关需拨到F档。连接成功后终端界面显示如下：

wang@wang:~/catkin_ws$ roslaunch dji_sdk sdk.launch... logging to /home/wang/.ros/log/9834××××××××b-11××××××-701c××××××b6/roslaunch-wang-7623.logChecking log directory for disk usage. This may take awhile.Press Ctrl-C to interruptDone checking log file disk usage. Usage is <1GB.started roslaunch server http://wang:41730/SUMMARYPARAMETERS * /dji_sdk/align_time: False * /dji_sdk/app_id: 1×××××0 * /dji_sdk/app_version: 1 * /dji_sdk/baud_rate: 230400 * /dji_sdk/enc_key: a287××××××××××ec8626... * /dji_sdk/serial_name: /dev/ttyUSB1 * /dji_sdk/use_broadcast: False * /rosdistro: kinetic * /rosversion: 1.12.7NODES  / dji_sdk (dji_sdk/dji_sdk_node)ROS_MASTER_URI=http://localhost:11311core service [/rosout] foundprocess[dji_sdk-1]: started with pid [7641]STATUS/1 @ init, L37: Attempting to open device /dev/ttyUSB1 with baudrate 230400...STATUS/1 @ init, L47: ...Serial started successfully.[ INFO] [1502851643.785412888]: Succeeded to read from serial deviceSTATUS/1 @ init, L37: Attempting to open device /dev/ttyUSB1 with baudrate 230400...STATUS/1 @ init, L47: ...Serial started successfully.STATUS/1 @ parseDroneVersionInfo, L568: Device Serial No. = 0DBDE4T0020006STATUS/1 @ parseDroneVersionInfo, L570: Hardware = N3STATUS/1 @ parseDroneVersionInfo, L571: Firmware = 3.2.36.8ERROR/1 @ initGimbal, L677: Failed to verify subscription!ERROR/1 @ functionalSetUp, L157: Failed to initialize Gimbal!ERROR/1 @ functionalSetUp, L187: Virtual RC not supported!STATUS/1 @ getErrorCodeMessage, L590: removePackageSTATUS/1 @ getCMDSetSubscribeMSG, L672: SUBSCRIBER_ILLEGAL_INPUTSTATUS/1 @ getErrorCodeMessage, L590: removePackageSTATUS/1 @ getCMDSetSubscribeMSG, L672: SUBSCRIBER_ILLEGAL_INPUTSTATUS/1 @ getErrorCodeMessage, L590: removePackageSTATUS/1 @ getCMDSetSubscribeMSG, L672: SUBSCRIBER_ILLEGAL_INPUTSTATUS/1 @ getErrorCodeMessage, L590: removePackageSTATUS/1 @ getCMDSetSubscribeMSG, L672: SUBSCRIBER_ILLEGAL_INPUTSTATUS/1 @ getErrorCodeMessage, L590: removePackageSTATUS/1 @ getCMDSetSubscribeMSG, L672: SUBSCRIBER_ILLEGAL_INPUTSTATUS/1 @ activate, L951: version 0x3022408STATUS/1 @ activate, L964: Activation successful[ INFO] [1502851645.001466961]: drone activated[ INFO] [1502851645.022345163]: Use data subscription to get telemetry data![ INFO] [1502851645.022363712]: align_time_with_FC set to false. We will use ros time to time stamp messages!STATUS/1 @ startPackage, L314: Start package 2 result: 0.STATUS/1 @ startPackage, L316: Package 2 info: freq=100, nTopics=3.STATUS/1 @ startPackage, L314: Start package 1 result: 0.STATUS/1 @ startPackage, L316: Package 1 info: freq=50, nTopics=9.STATUS/1 @ startPackage, L314: Start package 0 result: 0.STATUS/1 @ startPackage, L316: Package 0 info: freq=10, nTopics=6.STATUS/1 @ startPackage, L314: Start package 3 result: 0.

5- ROS 节点启动成功后断开DJI ASSISITANT 2，然后新开终端并运行

source devel/setup.bashrosrun dji_sdk_demo demo_flight_control

飞机运行，终端界面显示：

wang@wang:~/catkin_ws$ rosrun dji_sdk_demo demo_flight_control[ INFO] [1502852234.628554866]: A3/N3 taking off![ INFO] [1502852234.784108884]: Motor Spinning ...