（ROS学习笔记）通过键盘、串口控制ROS机器人运动--by teleop_twist_keyboard & serial

控制原理

1.按下键盘时，teleop_twist_keyboard Package发布名为 /cmd_vel 的Topic

2.创建一个Package，创建 base_controller 节点订阅这个话题，接收速度数据，在转换成与底盘通信的格式，然后写入串口

3.当小车底盘接收到串口发来的速度后，就控制电机运转，从而实现键盘控制小车的移动

测试：

1、打开键盘

# rosrun teleop_twist_keyboard teleop_twist_keyboard.py

2、运行功能包

#rosrun base_controller base_controller

ps: 查看Twist发布的cmd_vel话题

# rostopic list
# rostopic echo /cmd_vel

必须保证USB转串口线连接在树莓派ttyUSB1上

ls -l /dev |grep ttyUSB  #查看USB口

3、在teleop_twist_keyboard上按键进行控制
teleop_twist_keyboard有两种控制方式：1.普通模式 2.全向模式
本项目采用四全向轮故使用模式2（大写锁定可启动）。

步骤：

0、准备工作：

cd ~/catkin_ws/src
git clone https://github.com/Forrest-Z/teleop_twist_keyboard.git
git clone https://github.com/Forrest-Z/serial.git

1、创建创建一个Package #一定要到catkin_ws/src 文件夹下进行创建！

# catkin_create_pkg base_controller std_msgs rospy roscpp

创建时需要添加依赖，ROS会自动在package.xml 文件里添加这些依赖。

2、写一个小Node（cpp）
在base_controller/src 目录下创建base_controller.cpp

# roscd base_controller
# touch base_controller.cpp
# gedit base_controller.cpp 

代码：

/****************************************************
ROS Robot control base on serial
Making sure ttyUSB1 !!! 
function :
1.transmit control conmmand to control robot moving 
2.Subscribe /cmd_vel(keyboard transmit)
   Twist msgs 
serial commend:
14 Byte:[linear_speed_X 4 Byte][linear_speed_Y 4 Byte][angular_speed_Z 4 4Byte][end "\r\n" 2 Byte]
****************************************************/

#include "ros/ros.h" 
#include 

#include 
#include 
#include 
#include 
#include 
#include "serial/serial.h"

using std::string;
using std::exception;
using std::cout;
using std::cerr;
using std::endl;
using std::vector;

float linear_temp_x=0,linear_temp_y=0,angular_temp_z=0;

unsigned char data_terminal0=0x0d;  //   "/r"
unsigned char data_terminal1=0x0a;  //   "/n"
unsigned char speed_data[14]={0} ;    //serial data

union floatData
{
  float d;
  unsigned char data[4];
}linear_speed_x,linear_speed_y,angular_speed_z;

void callback(const geometry_msgs::Twist & cmd_input) //Subscribe Twist
{
 string port("/dev/ttyUSB0");
 unsigned long baud = 115200;
 serial::Serial my_serial(port, baud, serial::Timeout::simpleTimeout(1000));

 linear_temp_x  = cmd_input.linear.x;
 linear_temp_y  = cmd_input.linear.y;
 angular_temp_z = cmd_input.angular.z;

 linear_speed_x.d = linear_temp_x ;
 linear_speed_y.d = linear_temp_y ;
 angular_speed_z.d= angular_temp_z;

 for(int i=0;i<4;i++)
  {
    speed_data[i]   = linear_speed_x.data[i] ;
    speed_data[i+4] = linear_speed_y.data[i] ;
    speed_data[i+8] = angular_speed_z.data[i];
  }
 speed_data[12]=data_terminal0;
 speed_data[13]=data_terminal1;

 //write to serial
 my_serial.write(speed_data,14);
}

int main(int argc, char **argv)
{
 string port("/dev/ttyUSB0");
 unsigned long baud = 115200;
 serial::Serial my_serial(port,baud,serial::Timeout::simpleTimeout(1000));

 ros::init(argc, argv, "base_controller"); //init Node
 ros::NodeHandle n; 

 ros::Subscriber sub = n.subscribe("cmd_vel", 20, callback);
 ros::spin();

 return 0;
}

修改 CMakeLists：

cmake_minimum_required(VERSION 2.8.3)
project(base_controller)

find_package(catkin REQUIRED COMPONENTS
  roscpp
  rospy
  std_msgs
  message_generation
  serial
)


catkin_package(
  CATKIN_DEPENDS roscpp rospy std_msgs
)

include_directories(
  ${catkin_INCLUDE_DIRS}
  ${serial_INCLUDE_DIRS}
)


add_executable(base_controller src/base_controller.cpp)



## Specify libraries to link a library or executable target against
target_link_libraries(base_controller ${catkin_LIBRARIES})

编译(catkin_ws 目录下)

# catkin_make

节点创建结束

到此，已经可以使用文首测试模块进行测试。

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新：添加launch文件

功能

使 Node：teleop_twist_keyboard 和 base_controller 同时启动

步骤
1、创建launch

# roscd base_controller
# mkdir launch
# cd launch
# gedit keycontrol.launch

2、编辑如下