ROS Usage Tutorial

This document introduces the basic usage of ROS, including creating a workspace, configuring a URDF model, controlling the robot via MoveIt, and implementing control through C++ programming. You can also follow the video tutorial NexDroid and ROS Integration - Connection and Usage for guided learning.

1. Create a Workspace

mkdir -p ~/inexbot/src
cd ~/inexbot/src
catkin_init_workspace

If an error occurs:

Run the following command:

ls -al ~/inexbot/src

Then re-run the workspace initialization command:

catkin_init_workspace
cd ../
catkin_make

2. Configure ~/.bashrc

gedit ~/.bashrc

Add the following at the end of the file:

source ~/inexbot/devel/setup.bash

Copy the inexbot package to the ~/inexbot/src directory.

3. Configure MoveIt

Install MoveIt

Open a new terminal and run:

sudo apt-get install ros-melodic-moveit
source /opt/ros/melodic/setup.bash
sudo apt-get install ros-melodic-moveit-resources

Launch MoveIt Setup Assistant

cd ~/inexbot
source ./devel/setup.bash
roslaunch moveit_setup_assistant setup_assistant.launch

Copy the two folders from the inexbot_driver file and the generated moveit file:

In qj_ws/src/inexbot_support/launch, change all default moveit folder names in moveit_planning_execution.launch to qj_moveit (the actual name of the moveit folder):

In inexbot_support/config, change the joint names in the two .yaml files to match the joint names in the URDF:

In qj_moveit/launch/qj_moveit_controller_manager.launch.xml, change the content highlighted in the red box to (find inexbot_support)/config/controllers.yaml:

Open a terminal, build and launch:

cd ~/inexbot
catkin_make
source devel/setup.bash
roslaunch inexbot_support moveit_planning_execution.launch sim:=false robot_ip:=192.168.1.13

4. Control the Robot via MoveIt

Method 1: Set Goal State

Click Plan to generate a planned trajectory. The computation time will be displayed at the bottom.

Click Execute to run the motion, or click Plan & Execute to plan and execute immediately.

Method 2: Drag Planner

Drag the green sphere at the end of the motion planner. When hovering over the sphere, a 3D coordinate appears below it. Drag to the target position, click Plan to generate the planned trajectory, then click Execute to run it, or click Plan & Execute to plan and execute immediately.

5. C++ Programming to Control the Robot

Create a Package

cd ~/inexbot/src
catkin_create_pkg inexbot_code std_msgs rospy roscpp
cd ../
catkin_make

Joint Space Planning Example

Save the following code as src/moveit_joint_demo.cpp and place it in ~/inexbot/src/inexbot_code/src/:

#include <ros/ros.h>
#include <moveit/move_group_interface/move_group_interface.h>

int main(int argc, char **argv)
{
    ros::init(argc, argv, "moveit_joint_demo");
    ros::AsyncSpinner spinner(1);
    spinner.start();

    // "manipulator" is the planning group name set through MoveIt
    moveit::planning_interface::MoveGroupInterface arm("manipulator");

    // Set joint tolerance
    arm.setGoalJointTolerance(0.001);
    // Set maximum acceleration
    arm.setMaxAccelerationScalingFactor(0.2);
    // Set maximum velocity
    arm.setMaxVelocityScalingFactor(0.2);

    // Move the arm to the initial position ("home" is a MoveIt preset position)
    arm.setNamedTarget("home");
    arm.move();
    sleep(1);

    // Set six joint angles in joint space
    double targetPose[6] = {0.391410, -0.676384, -0.376217, 0.0, 1.052834, 0.454125};
    std::vector<double> joint_group_positions(6);
    joint_group_positions[0] = targetPose[0];
    joint_group_positions[1] = targetPose[1];
    joint_group_positions[2] = targetPose[2];
    joint_group_positions[3] = targetPose[3];
    joint_group_positions[4] = targetPose[4];
    joint_group_positions[5] = targetPose[5];

    arm.setJointValueTarget(joint_group_positions);
    arm.move();
    sleep(1);

    // Move the arm back to the initial position
    arm.setNamedTarget("home");
    arm.move();
    sleep(1);

    ros::shutdown();
    return 0;
}

Modify CMakeLists.txt

Add the following above the add_executable tag:

add_executable(moveit_joint_demo src/moveit_joint_demo.cpp)
target_link_libraries(moveit_joint_demo ${catkin_LIBRARIES})

Build and Run

cd ~/inexbot
catkin_make
rosrun inexbot_code moveit_joint_demo