一、所需工具包

1.ROS键盘包:teleop_twist_keyboard

2.TCP通讯包:socket

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

3.在ubuntu的ros中建立一个ros_car_py包:

  • $ cd ~/catkin_ws/src
  • $ catkin_create_pkg ros_car_py roscpp rospy std_msgs

4.新建 base 文件:

  • $ cd catkin_ws/src/base
  • $ mkdir src
  • $ vim src/base.py

代码如下(ROS作为TCP服务器):

    #!/usr/bin/env python
# coding=utf-8
import rospy
from socket import *
import time
from threading import Thread
from std_msgs.msg import String
from geometry_msgs.msg import Twist
msg_list = []
def callback(cmd_input, Socket):
print("-----服务器已经启动成功,准备接收数据-----")
Socket.settimeout(5)
recvdata = Socket.recv(4096)
t = Twist()
t.angular.z = cmd_input.angular.z
t.linear.x = cmd_input.linear.x
left_speed = t.linear.x - t.angular.z * 0.5 * 0.2
right_speed = t.linear.x + t.angular.z * 0.5 * 0.2
left_speed *= 1000
right_speed *= 1000
left_speed = str(left_speed)
right_speed = str(right_speed)
# msg_list.append(left_speed)
# msg_list.append(right_speed)
print("left_speed=%s" % left_speed)
print("right_speed=%s" % right_speed)
if len(recvdata) != 0:
  print("-----接收到数据-----")
  print("recvdata:%s" % recvdata)
   # Socket.send(b"hello beaglebone")
   # Socket.send(b"左轮速度")
   Socket.send(left_speed.encode("utf-8"))
  # Socket.send(b"右轮速度")
  Socket.send(right_speed.encode("utf-8"))
  # Socket.send(msg_list)
else:
  print('-----未接收到客户端数据,可能连接已经断开-----')
  # Socket.send(b'client off')
  # 数据中断时进行服务重启程序,先close 再accept等待重新连线
  # 可以防止出现当client意外终止导致server的中断(Broken pipe错误)
   print('-----正在重新建立连接-----')
   Socket.close()
Socket, clientInfo = serverSocket.accept()
# serverSocket.close()
def main():
rospy.init_node("base")
serverSocket = socket(AF_INET, SOCK_STREAM)
serverSocket.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
serverSocket.bind(('', 8899))
serverSocket.listen(5)
print("-----服务器正在启动-----")
Socket, clientInfo = serverSocket.accept()
sub = rospy.Subscriber("cmd_vel", Twist, callback, Socket)
rate = rospy.Rate(10)
rospy.spin()
if __name__ == "__main__":
main()

  

注意事项:

  • ROS中的python是python2,使用python3会出错,所以需要在开头加上#!/usr/bin/env python
  • 编写好python程序后,编译成功但是无法运行,报错Couldn't find executable named XXX.py,无法执行
  • 问题原因:
  • 文件没有执行权限
  • 解决办法:
  • 给文件添加执行权限
  • 命令:chmod +x base.py

修改CMakeList.txt:

  1. cmake_minimum_required(VERSION 2.8.3)
  2. project(ros_car_py)
  3. find_package(catkin REQUIRED COMPONENTS
  4. roscpp
  5. rospy
  6. std_msgs
  7. message_generation
  8. )
  9. add_message_files(
  10. FILES
  11. MsgCar.msg
  12. )
  13. generate_messages(
  14. DEPENDENCIES
  15. std_msgs
  16. )
  17. catkin_package(
  18. #  INCLUDE_DIRS include
  19. #  LIBRARIES ros_car_py
  20. CATKIN_DEPENDS message_runtime
  21. #roscpp rospy std_msgs
  22. #  DEPENDS system_lib
  23. )
  24. include_directories(
  25. # include
  26. ${catkin_INCLUDE_DIRS}
  27. )

单独编译ros_car_pkg包:

  • $ catkin_make -DCATKIN_WHITELIST_PACKAGES='ros_car_py'

二、控制原理:

  • 当我们按下键盘时,teleop_twist_keyboard 包会发布 /cmd_vel 发布速度主题
  • 在 base 节点订阅这个话题,接收速度数据,转换成字符串(TCP只允许发送字符串),然后发送至客户端

设置beaglebone作为客户端:

运行代码加载设备树并读串口数据用于控制PWM,进而控制小车运动

    from socket import *
import time
SLOTS = "/sys/devices/bone_capemgr.9/slots"
p1_duty = "/sys/devices/ocp.3/pwm_test_P9_16.16/duty"
p2_duty = "/sys/devices/ocp.3/pwm_test_P8_13.15/duty"
p1_period = "/sys/devices/ocp.3/pwm_test_P9_16.16/period"
p2_period = "/sys/devices/ocp.3/pwm_test_P8_13.15/period"
p1_run = "/sys/devices/ocp.3/pwm_test_P9_16.16/run"
p2_run = "/sys/devices/ocp.3/pwm_test_P8_13.15/run"
p1_export = "/sys/class/gpio/export"
p2_export = "/sys/class/gpio/export"
p1_direction = "/sys/class/gpio/gpio44/direction"
p2_direction = "/sys/class/gpio/gpio45/direction"
p1_polarity = "/sys/class/gpio/gpio44/value"
p2_polarity = "/sys/class/gpio/gpio45/value"
msg_lists = []
clientSocket = socket(AF_INET, SOCK_STREAM)
clientSocket.connect(("192.168.1.151", 8899))
try:
with open(SLOTS, "a") as f:
   f.write("am33xx_pwm")
with open(SLOTS, "a") as f:
  f.write("bone_pwm_P9_22")
with open(SLOTS, "a") as f:
  f.write("bone_pwm_P9_16")
with open(p1_export, "a") as f:
   f.write("44")
with open(p2_export, "a") as f:
   f.write("45")
with open(p1_direction, "a") as f:
  f.write("in")
with open(p2_direction, "a") as f:
   f.write("in")
except:
pass
while True:
clientSocket.send(b"hello ROS")
msg_list1 = clientSocket.recv(1024)
msg_list2 = clientSocket.recv(1024)
if len(msg_list1) or len(msg_list2) > 0:
msg_lists.append(msg_list1)
msg_lists.append(msg_list2)
for msg in msg_lists:
print("recvData:%s" % msg)
if msg_lists[0] == '500.0' and msg_lists[1] == '500.0':
msg_lists = []
print("succes")
try:
with open(p1_period, "a") as f:
f.write("500000")
with open(p1_duty, "a") as f:
f.write("250000")
with open(p2_period, "a") as f:
f.write("500000")
with open(p2_duty, "a") as f:
f.write("250000")
with open(p1_run, "a") as f:
f.write("1")
with open(p2_run, "a") as f:
f.write("1")
with open(p1_polarity, "a") as f:
f.write("1")
with open(p2_polarity, "a") as f:
f.write("1")
except:
pass
elif msg_lists[0] == '400.0' and msg_lists[1] == '600.0':
msg_lists = []
try:
with open(p1_period, "a") as f:
f.write("400000")
with open(p1_duty, "a") as f:
f.write("200000")
with open(p2_period, "a") as f:
f.write("600000")
with open(p2_duty, "a") as f:
f.write("300000")
with open(p1_run, "a") as f:
f.write("1")
with open(p2_run, "a") as f:
f.write("1")
with open(p1_polarity, "a") as f:
f.write("1")
with open(p2_polarity, "a") as f:
f.write("1")
except:
pass
elif msg_lists[0] == '600.0' and msg_lists[1] == '400.0':
msg_lists = []
try:
with open(p1_period, "a") as f:
f.write("600000")
with open(p1_duty, "a") as f:
f.write("300000")
with open(p2_period, "a") as f:
f.write("400000")
with open(p2_duty, "a") as f:
f.write("200000")
with open(p1_run, "a") as f:
f.write("1")
with open(p2_run, "a") as f:
f.write("1")
with open(p1_polarity, "a") as f:
f.write("1")
with open(p2_polarity, "a") as f:
f.write("1")
except:
pass
elif msg_lists[0] == '-500.0' and msg_lists[1] == '-500.0':
msg_lists = []
try:
with open(p1_period, "a") as f:
f.write("500000")
with open(p1_duty, "a") as f:
f.write("250000")
with open(p2_period, "a") as f:
f.write("500000")
with open(p2_duty, "a") as f:
f.write("250000")
with open(p1_run, "a") as f:
f.write("1")
with open(p2_run, "a") as f:
f.write("1")
with open(p1_polarity, "a") as f:
f.write("0")
with open(p2_polarity, "a") as f:
f.write("0")
except:
pass
elif msg_lists[0] == '-600.0' and msg_lists[1] == '-400.0':
msg_lists = []
try:
with open(p1_period, "a") as f:
f.write("600000")
with open(p1_duty, "a") as f:
f.write("300000")
with open(p2_period, "a") as f:
f.write("400000")
with open(p2_duty, "a") as f:
f.write("200000")
with open(p1_run, "a") as f:
f.write("1")
with open(p2_run, "a") as f:
f.write("1")
with open(p1_polarity, "a") as f:
f.write("0")
with open(p2_polarity, "a") as f:
f.write("0")
except:
pass
elif msg_lists[0] == '-400.0' and msg_lists[1] == '-600.0':
msg_lists = []
try:
with open(p1_period, "a") as f:
f.write("400000")
with open(p1_duty, "a") as f:
f.write("200000")
with open(p2_period, "a") as f:
f.write("600000")
with open(p2_duty, "a") as f:
f.write("300000")
with open(p1_run, "a") as f:
f.write("1")
with open(p2_run, "a") as f:
f.write("1")
with open(p1_polarity, "a") as f:
f.write("0")
with open(p2_polarity, "a") as f:
f.write("0")
except:
pass
elif msg_lists[0] == '0.0' and msg_lists[1] == '0.0':
msg_lists = []
try:
with open(p1_run, "a") as f:
f.write("0")
with open(p2_run, "a") as f:
f.write("0")
except:
pass
else:
pass
else:
time.sleep(0.1)
clientSocket = socket(AF_INET, SOCK_STREAM)
clientSocket.connect(("192.168.1.138", 8899))

  

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