Snake Robot

a 7-DoF snake robot.

Robotis Dynamixel MX-28AR, Protocol1.0.

Ubuntu 16.04 LTS, ROS kinetic, ROS Control.

Install

# 1. install ros kinetic and create workspace

# 2. install dynamixel lib
git clone https://github.com/ROBOTIS-GIT/DynamixelSDK.git
cd DynamixelSDK/c++/build/linux64
make
sudo make install
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/lib # add dynamixel lib install path

# 3. get code
cd ~/catkin_ws/src
git clone https://github.com/guzhaoyuan/snake_robot.git
git clone https://github.com/guzhaoyuan/snake_moveit_config.git
cd ..
catkin_make

Note: dynamixel communicate using RS485, the official hardware for communicating with dynamixel is USB2Dynamixel. After insert USB2Dynamixel:

sudo chmod 777 /dev/ttyUSB0

Warning: before making any move, make sure the sorvo is not gonna interfere with anything to prevent damage or harm!!

Design

Hardware Setup

Demo

• ping servo.

    cd snake_robot/test/ping
    make
    ./ping
  

• Draw a circle using 2 joints.

    roslaunch snake_robot display_twoJointsSnake.launch 
  

• Draw a circle using 7 joints.

    roslaunch snake_robot display_sevenJointSnake.launch 
  

• simulate snake using ros control

    roslaunch snake_robot snake_world.launch # launch gazebo and load urdf snake
    roslaunch snake_robot snake_robot_control.launch # pop up controllers for each joint
    rostopic pub /snake/joint1_position_controller/command std_msgs/Float64 "data: 1.0" # send command to controller
  

• control real snake using ros control

    roslaunch snake_robot main.launch # launch main including controller_manager and pop up controllers for each joint and keep updating state
    rostopic pub /snake/joint1_position_controller/command std_msgs/Float64 "data: 0.1" # send command to controller
  

• control real 2 joint snake to draw ellipse using ros control

    roslaunch snake_robot main.launch # launch main including controller_manager and pop up controllers for each joint and keep updating state
    roslaunch snake_robot display_twoJointsSnake.launch # publish to joint's command topic to control real robot
  

• IK for a 3-DoF snake

    roslaunch three_joint_snake_moveit_config demo.launch
    rosrun snake_robot IK_client 
  

• IK for a 7-DoF snake to draw circle

    roslaunch seven_joint_snake_moveit_config demo.launch
    rosrun snake_robot showpath link8 # you can show path of any link in the robot 
  

TODO

• soft limit and transmission jnt motor space convert
• put the snake in gazebo to see how it does in real world
• IK for 2-DoF snake
• implement position interface
• drive one motor
• resource management
• IK for 7-DoF snake
• Draw a circle using 7 joint.

Resources

• eManual
• Protocol 1.0
• git manual
• drawing
• ros dynamixel tutorial
• robotHW that I consult from