2、MoveIt control the real machine

MoveIt website：http://docs.ros.org/en/melodic/api/moveit_tutorials/html/index.html

2.1、Prepare

According to different models, you only need to set the purchased model in [.bashrc], X1 (ordinary four-wheel drive) X3 (Mike wheel) X3plus (Mike wheel mechanical arm) R2 (Ackerman differential) and so on. Section takes X3 as an example

Open the [.bashrc] file

sudo vim .bashrc

Find the [ROBOT_TYPE] parameter and modify the corresponding model

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export ROBOT_TYPE=X3plus   # ROBOT_TYPE: X1 X3 X3plus R2 X7

This lesson applies to all MoveIT cases for robots; MoveIT is mainly for robots with robotic arms.

2.2. Simulation startup

Just control the robot in the simulation under the MoveIT simulation.

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roslaunch arm_moveit_demo x3plus_moveit_demo.launch sim:=true  # Recommended virtual machine

Parameter use_rviz: Whether to enable rviz, if true, enable.

Parameter use_gui: Whether to open the GUI control interface, if true, this parameter is only valid when sim is true.

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rqt_graph

Node diagram is as follows:

2.3. Control real machine

Controlling the real machine is to control the real robot in combination with MoveIT.

• Host by robots

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roslaunch yahboomcar_bringup bringup.launch                     # robot end
roslaunch arm_moveit_demo x3plus_moveit_demo.launch sim:=false  # Recommended virtual machine

• Host virtual machine

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roscore                                                         # virtual machine
roslaunch yahboomcar_bringup bringup.launch                     # robot end
roslaunch arm_moveit_demo x3plus_moveit_demo.launch sim:=false  # Recommended virtual machine

Node diagram is as follows:

Corresponding relationship between robotic arm servos and joints: from the lowest end of the robotic arm to the end of the gripper.

Handle to control robotic arm

Handle【R2】button: Get the current joint angle of the mechanical arm.

Use the handle 【SELECT】button to switch control 【joint 5】or control 【gripper】.

At this point, use the handle to control the robotic arm, and you will find that the real machine runs synchronously with the MoveIT simulation.

2.4.matters needing attention

Note: There may be problems, not necessarily.

2.4.1. Start the robotic arm

Regardless of whether you are using MoveIT or not, when you start the handle to control the real robot, thehandle state is connected, but the robot cannot be controlled.In this case, the handle control node may be acquiring the current position of the manipulator, and the current position data of the manipulator is [-1] (out of range or read failure).

Solution: Click the [START] button of the handle several times, and at the same time grab the gripper and gently shake the mechanical arm up and down until the buzzer sounds.

2.4.2.Start the MoveIT

The MoveIt simulation environment starts slowly, wait patiently and observe the terminal. An error as shown in the figure below occurs. The solution is shown in the figure. If the terminal reports an error and the motion planning library is not loaded, click [Reset] in the lower left corner to reload. At first, during the loading process, don't click [Reset] in a hurry. If you click it before it is loaded, the system will be reloaded, so it can't be started.

As shown in the figure below, if [Replanning: yes] appears on the terminal, and green [OMPL] appears below the Planning Library, the startup is successful.