5. 键盘控制smartcar
博客转自：https://blog.csdn.net/hcx25909/article/details/9004617
如果尝试过前面的例子，有没有感觉每次让机器人移动还要在终端里输入指令，这也太麻烦了，有没有办法通过键盘来控制机器人的移动呢？答案室当然的了。我研究了其他几个机器人键盘控制的代码，还是有所收获的，最后移植到了smartcar上，实验成功。
一、创建控制包
首先，我们为键盘控制单独建立一个包：
roscreate-pkg smartcar_teleop rospy geometry_msgs std_msgs roscpp rosmake
二、简单的消息发布
在机器人仿真中，主要控制机器人移动的就是 Twist()结构，如果我们编程将这个结构通过程序发布成topic，自然就可以控制机器人了。我们先用简单的python来尝试一下。 之前的模拟中，我们使用的都是在命令行下进行的消息发布，现在我们需要把这些命令转换成python代码，封装到一个单独的节点中去。针对之前的命令行，我们可以很简单的在smartcar_teleop /scripts文件夹下编写如下的控制代码：
#!/usr/bin/env python
import roslib; roslib.load_manifest('smartcar_teleop')
import rospy
from geometry_msgs.msg import Twist
from std_msgs.msg import String
class Teleop:
def __init__(self):
pub = rospy.Publisher('cmd_vel', Twist)
rospy.init_node('smartcar_teleop')
rate = rospy.Rate(rospy.get_param('~hz', 1))
self.cmd = None
cmd = Twist()
cmd.linear.x = 0.2
cmd.linear.y = 0
cmd.linear.z = 0
cmd.angular.z = 0
cmd.angular.z = 0
cmd.angular.z = 0.5
self.cmd = cmd
while not rospy.is_shutdown():
str = "hello world %s" % rospy.get_time()
rospy.loginfo(str)
pub.publish(self.cmd)
rate.sleep()
if __name__ == '__main__':Teleop()
python代码在ROS中是不需要编译的。先运行之前教程中用到的smartcar机器人，在rviz中进行显示，然后新建终端，输入如下命令：
rosrun smartcar_teleop teleop.py
也可以建立一个launch文件运行：
<launch>
<arg name="cmd_topic" default="cmd_vel" />
<node pkg="smartcar_teleop" type="teleop.py" name="smartcar_teleop">
<remap from="cmd_vel" to="$(arg cmd_topic)" />
</node>
</launch>
在rviz中看一下机器人是不是动起来了！
三、加入键盘控制
1、移植
因为ROS的代码具有很强的可移植性，所以用键盘控制的代码其实可以直接从其他机器人包中移植过来，在这里我主要参考的是erratic_robot，在这个机器人的代码中有一个erratic_teleop包，可以直接移植过来使用。首先，我们将其中src文件夹下的keyboard.cpp代码文件直接拷贝到我们smartcar_teleop包的src文件夹下，然后修改CMakeLists.txt文件，将下列代码加入文件底部：
rosbuild_add_boost_directories() rosbuild_add_executable(smartcar_keyboard_teleop src/keyboard.cpp) target_link_libraries(smartcar_keyboard_teleop boost_thread)
编译完成后，运行smartcar模型。重新打开一个终端，打开键盘控制节点并在终端中按下键盘里的“W”、“S”、“D”、“A”以及“Shift”键进行机器人的控制。效果如下图
键盘控制代码复用
因为代码是我们直接复制过来的，其中有很多与之前erratic机器人相关的变量，我们把代码稍作修改，变成自己机器人可读性较强的代码。
#include <termios.h>
#include <signal.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/poll.h>
#include <boost/thread/thread.hpp>
#include <ros/ros.h>
#include <geometry_msgs/Twist.h>
#define KEYCODE_W 0x77
#define KEYCODE_A 0x61
#define KEYCODE_S 0x73
#define KEYCODE_D 0x64
#define KEYCODE_A_CAP 0x41
#define KEYCODE_D_CAP 0x44
#define KEYCODE_S_CAP 0x53
#define KEYCODE_W_CAP 0x57
class SmartCarKeyboardTeleopNode
{
private:
double walk_vel_;
double run_vel_;
double yaw_rate_;
double yaw_rate_run_;
geometry_msgs::Twist cmdvel_;
ros::NodeHandle n_;
ros::Publisher pub_;
public:
SmartCarKeyboardTeleopNode()
{
pub_ = n_.advertise<geometry_msgs::Twist>("cmd_vel", 1);
ros::NodeHandle n_private("~");
n_private.param("walk_vel", walk_vel_, 0.5);
n_private.param("run_vel", run_vel_, 1.0);
n_private.param("yaw_rate", yaw_rate_, 1.0);
n_private.param("yaw_rate_run", yaw_rate_run_, 1.5);
}
~SmartCarKeyboardTeleopNode() { }
void keyboardLoop();
void stopRobot()
{
cmdvel_.linear.x = 0.0;
cmdvel_.angular.z = 0.0;
pub_.publish(cmdvel_);
}
};
SmartCarKeyboardTeleopNode* tbk;
int kfd = 0;
struct termios cooked, raw;
bool done;
int main(int argc, char** argv)
{
ros::init(argc,argv,"tbk", ros::init_options::AnonymousName | ros::init_options::NoSigintHandler);
SmartCarKeyboardTeleopNode tbk;
boost::thread t = boost::thread(boost::bind(&SmartCarKeyboardTeleopNode::keyboardLoop, &tbk));
ros::spin();
t.interrupt();
t.join();
tbk.stopRobot();
tcsetattr(kfd, TCSANOW, &cooked);
return(0);
}
void SmartCarKeyboardTeleopNode::keyboardLoop()
{
char c;
double max_tv = walk_vel_;
double max_rv = yaw_rate_;
bool dirty = false;
int speed = 0;
int turn = 0;
// get the console in raw mode
tcgetattr(kfd, &cooked);
memcpy(&raw, &cooked, sizeof(struct termios));
raw.c_lflag &=~ (ICANON | ECHO);
raw.c_cc[VEOL] = 1;
raw.c_cc[VEOF] = 2;
tcsetattr(kfd, TCSANOW, &raw);
puts("Reading from keyboard");
puts("Use WASD keys to control the robot");
puts("Press Shift to move faster");
struct pollfd ufd;
ufd.fd = kfd;
ufd.events = POLLIN;
for(;;)
{
boost::this_thread::interruption_point();
// get the next event from the keyboard
int num;
if ((num = poll(&ufd, 1, 250)) < 0)
{
perror("poll():");
return;
}
else if(num > 0)
{
if(read(kfd, &c, 1) < 0)
{
perror("read():");
return;
}
}
else
{
if (dirty == true)
{
stopRobot();
dirty = false;
}
continue;
}
switch(c)
{
case KEYCODE_W:
max_tv = walk_vel_;
speed = 1;
turn = 0;
dirty = true;
break;
case KEYCODE_S:
max_tv = walk_vel_;
speed = -1;
turn = 0;
dirty = true;
break;
case KEYCODE_A:
max_rv = yaw_rate_;
speed = 0;
turn = 1;
dirty = true;
break;
case KEYCODE_D:
max_rv = yaw_rate_;
speed = 0;
turn = -1;
dirty = true;
break;
case KEYCODE_W_CAP:
max_tv = run_vel_;
speed = 1;
turn = 0;
dirty = true;
break;
case KEYCODE_S_CAP:
max_tv = run_vel_;
speed = -1;
turn = 0;
dirty = true;
break;
case KEYCODE_A_CAP:
max_rv = yaw_rate_run_;
speed = 0;
turn = 1;
dirty = true;
break;
case KEYCODE_D_CAP:
max_rv = yaw_rate_run_;
speed = 0;
turn = -1;
dirty = true;
break;
default:
max_tv = walk_vel_;
max_rv = yaw_rate_;
speed = 0;
turn = 0;
dirty = false;
}
cmdvel_.linear.x = speed * max_tv;
cmdvel_.angular.z = turn * max_rv;
pub_.publish(cmdvel_);
}
}
参考链接：http://ros.org/wiki/turtlebot_teleop/Tutorials/Teleoperation和http://www.ros.org/wiki/simulator_gazebo/Tutorials/TeleopErraticSimulation
键盘控制代码Python实现
虽然很多机器人的键盘控制使用的都是C++编写的代码，但是考虑到python的强大，我们还是需要尝试使用python来编写程序。首先需要理解上面C++程序的流程。在上面的程序中，我们单独创建了一个线程来读取中断中的输入，然后根据输入发布不同的速度和角度消息。介于线程的概念还比较薄弱，在python中使用循环替代线程。然后需要考虑的只是如何使用python来处理中断中的输入字符，通过上网查找资料，发现使用的API和C++的基本是一致的。最终的程序如下：
#!/usr/bin/env python
# -*- coding: utf-8 -*
import os
import sys
import tty, termios
import roslib; roslib.load_manifest('smartcar_teleop')
import rospy
from geometry_msgs.msg import Twist
from std_msgs.msg import String
# 全局变量
cmd = Twist()
pub = rospy.Publisher('cmd_vel', Twist)
def keyboardLoop():
#初始化
rospy.init_node('smartcar_teleop')
rate = rospy.Rate(rospy.get_param('~hz', 1))
#速度变量
walk_vel_ = rospy.get_param('walk_vel', 0.5)
run_vel_ = rospy.get_param('run_vel', 1.0)
yaw_rate_ = rospy.get_param('yaw_rate', 1.0)
yaw_rate_run_ = rospy.get_param('yaw_rate_run', 1.5)
max_tv = walk_vel_
max_rv = yaw_rate_
#显示提示信息
print "Reading from keyboard"
print "Use WASD keys to control the robot"
print "Press Caps to move faster"
print "Press q to quit"
#读取按键循环
while not rospy.is_shutdown():
fd = sys.stdin.fileno()
old_settings = termios.tcgetattr(fd)
#不产生回显效果
old_settings[3] = old_settings[3] & ~termios.ICANON & ~termios.ECHO
try :
tty.setraw( fd )
ch = sys.stdin.read( 1 )
finally :
termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
if ch == 'w':
max_tv = walk_vel_
speed = 1
turn = 0
elif ch == 's':
max_tv = walk_vel_
speed = -1
turn = 0
elif ch == 'a':
max_rv = yaw_rate_
speed = 0
turn = 1
elif ch == 'd':
max_rv = yaw_rate_
speed = 0
turn = -1
elif ch == 'W':
max_tv = run_vel_
speed = 1
turn = 0
elif ch == 'S':
max_tv = run_vel_
speed = -1
turn = 0
elif ch == 'A':
max_rv = yaw_rate_run_
speed = 0
turn = 1
elif ch == 'D':
max_rv = yaw_rate_run_
speed = 0
turn = -1
elif ch == 'q':
exit()
else:
max_tv = walk_vel_
max_rv = yaw_rate_
speed = 0
turn = 0
#发送消息
cmd.linear.x = speed * max_tv;
cmd.angular.z = turn * max_rv;
pub.publish(cmd)
rate.sleep()
#停止机器人
stop_robot();
def stop_robot():
cmd.linear.x = 0.0
cmd.angular.z = 0.0
pub.publish(cmd)
if __name__ == '__main__':
try:
keyboardLoop()
except rospy.ROSInterruptException:
pass
参考链接：http://blog.csdn.net/marising/article/details/3173848和 http://nullege.com/codes/search/termios.ICANON
