基于ROS和python，通过TCP通信协议，完成键盘无线控制移动机器人运动

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))