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:
- cmake_minimum_required(VERSION 2.8.3)
project(ros_car_py)
find_package(catkin REQUIRED COMPONENTS
roscpp
rospy
std_msgs
message_generation
)
add_message_files(
FILES
MsgCar.msg
)
generate_messages(
DEPENDENCIES
std_msgs
)
catkin_package(
# INCLUDE_DIRS include
# LIBRARIES ros_car_py
CATKIN_DEPENDS message_runtime
#roscpp rospy std_msgs
# DEPENDS system_lib
)
include_directories(
# include
${catkin_INCLUDE_DIRS}
)
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))
