3.Keyboard control

3. Keyboard control

3. Keyboard control3.1, teleop_twist_keyboard.py3.2, transbot_keyboard.py

Function package path: ~/transbot_ws/src/transbot_ctrl

Start low-level control

jetson motherboard/Raspberry Pi 4B


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roslaunch transbot_bringup bringup.launch

Raspberry Pi 5

Before running, please confirm that the large program has been permanently closed

Enter docker

Note: If there is a terminal that automatically starts docker, or there is a docker terminal that has been opened, you can directly enter the docker terminal to run the command, and there is no need to manually start docker

Start docker manually


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./run_docker.sh


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roslaunch transbot_bringup bringup.launch

3.1, teleop_twist_keyboard.py

Wiki: http://wiki.ros.org/teleop_twist_keyboard

Source code: https://github.com/ros-teleop/teleop_twist_keyboard

This function package can be installed directly into the system. The factory image of the car has been installed, no need to reinstall it

Install
jetson motherboard/Raspberry Pi


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sudo apt-get install ros-melodic-teleop-twist-keyboard

Raspberry Pi 5

Enter the same docker from multiple terminals

Keep the program of the previous docker terminal running and open a new terminal

Enter the following command


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docker ps

Enter the same docker and use the following 18870bc3dc00 to modify the ID displayed on the actual terminal.


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docker exec -it 18870bc3dc00 /bin/bash


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sudo apt-get install ros-melodic-teleop-twist-keyboard

run
jetson motherboard/Raspberry Pi 4B


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rosrun teleop_twist_keyboard teleop_twist_keyboard.py

Raspberry Pi 5

Enter the same docker from multiple terminals

Keep the program of the previous docker terminal running and open a new terminal

Enter the following command


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docker ps

Enter the same docker and use the following 18870bc3dc00 to modify the ID displayed on the actual terminal.


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docker exec -it 18870bc3dc00 /bin/bash


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rosrun teleop_twist_keyboard teleop_twist_keyboard.py

control

Button	Car [linear, angular]	Button	Car [linear, angular]
[i] or [I]	[linear, 0]	[u] or [U]	[linear, angular]
[,]	[-linear, 0]	[o] or [O]	[linear, - angular]
[j] or [J]	[0, angular]	[m] or [M]	[- linear, - angular]
[l] or [L]	[0, - angular]	[.]	[- linear, angular]
Button	Speed change	Button	Speed change
[q]	Linear speed and angular speed are both increased by 10%	[z]	Linear speed and angular speed are both reduced by 10%
[w]	Only the linear speed increases by 10%	[x]	Only the linear speed decreases by 10%
[e]	Only the angular velocity increases by 10%	[c]	Only the angular velocity decreases by 10%

In addition to the above keys, any key stops movement. [Ctrl]+[c] to exit.

jetson motherboard/Raspberry Pi 4B


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rqt_graph

Raspberry Pi 5

Enter the same docker from multiple terminals

Keep the program of the previous docker terminal running and open a new terminal

Enter the following command


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docker ps

Enter the same docker and use the following 18870bc3dc00 to modify the ID displayed on the actual terminal.


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docker exec -it 18870bc3dc00 /bin/bash


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rqt_graph

The node [teleop_twist_keyboard] publishes a message to the topic [/cmd_vel] and is subscribed by the node [/transbot_node].

3.2, transbot_keyboard.py

Note: Button control method is the same as above

Start mode

jetson motherboard/Raspberry Pi 4B


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rosrun transbot_ctrl transbot_keyboard.py
roslaunch transbot_ctrl transbot_keyboard.launch

Raspberry Pi 5

Enter the same docker from multiple terminals

Keep the program of the previous docker terminal running and open a new terminal

Enter the following command


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docker ps

Enter the same docker and use the following 18870bc3dc00 to modify the ID displayed on the actual terminal.


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docker exec -it 18870bc3dc00 /bin/bash


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rosrun transbot_ctrl transbot_keyboard.py
roslaunch transbot_ctrl transbot_keyboard.launch

Code analysis

Mainly used select module, termios module and tty module


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import sys, select, termios, tty

The select module is mainly used for socket communication, seeing changes in file descriptions, and completing work in a non-blocking manner.
The termios module provides an interface for IO controlled POSIX calls for tty
The tty module is mainly used to change the mode of the file descriptor fd

Get current key information


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def getKey():
     #tty.setraw(): Change the file descriptor fd mode to raw; fileno(): Return an integer file descriptor (fd)
     tty.setraw(sys.stdin.fileno())
     # select(): Directly call the IO interface of the operating system; monitor all file handles with the fileno() method
     rlist, _, _ = select.select([sys.stdin], [], [], 0.1)
     # Read a byte input stream
     if rlist: key = sys.stdin.read(1)
     else: key = ''
     #tcsetattr sets the tty attribute of the file descriptor fd from the attribute
     termios.tcsetattr(sys.stdin, termios.TCSADRAIN, settings)
     return key

Get speed limit


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     linear_limit = rospy.get_param('~linear_limit', 0.45)
     angular_limit = rospy.get_param('~angular_limit', 2.0)

control flow


# Get current key information
             key = getKey()
             # Determine whether the key string is in the mobile dictionary
             if key in moveBindings.keys():
                 x = moveBindings[key][0]
                 th = moveBindings[key][1]
                 count = 0
             # Determine whether the key string is in the speed dictionary
             elif key in speedBindings.keys():
                 speed = speed * speedBindings[key][0]
                 turn = turn * speedBindings[key][1]
                 count = 0
                 # speed limit
                 if speed > linear_limit: speed = linear_limit
                 if turn > angular_limit: turn = angular_limit
                 print(vels(speed, turn))
                 # Print msg information a certain number of times cumulatively
                 if (status == 14): print(msg)
                 status = (status + 1) % 15
             # If the button is ' ' or 'k', stop the movement
             elif key == ' ': (x, th) = (0, 0)
             else:
                 #Set the function to stop the movement if it is not pressed for a long time
                 count = count + 1
                 if count > 4: (x, th) = (0, 0)
                 if (key == '\x03'): break
             # make an announcement
             twist = Twist()
             twist.linear.x = speed * x
             twist.angular.z = turn * th
             pub.publish(twist)