Welcome to JetCobot repository
1.Movelt configuration
Movelt configuration
Note: The configuration provided by Yahboom in this course is already complete. If you are using the mirror system provided by Yahboom, you can skip the Moveit configuration course.
1. Start roscore
Open the terminal and enter the following code
xxxxxxxxxxroscore
2. Start the MoveIt configuration tool
Open a new terminal.
Open the terminal and enter the following code
xxxxxxxxxxrosrun moveit_setup_assistant moveit_setup_assistant
3. Configuration process
Loading URDF models
If you get an error message 【Cannot find model】 when loading a model, exit MoveIt-->enter the workspace-->update the environment (source devel/ setup .bash)-->restart MoveIt configuration.
If you are loading a model to generate configuration for the first time, select the left side. If you are modifying an already generated configuration file, select the right side.
Click the Browse button, find the URDF model file, and click Load in the lower right corner.
Create an Avoid Collision Matrix (ACM)
Collision detection is a very complex calculation process. For multi-joint manipulators or humanoid robots, the mechanical structure is complex and there are many joints. Collision detection requires a lot of spatial geometry calculations. However, for rigid robots, some joints cannot collide, such as adjacent limbs. The purpose of generating self-collisions here is to tell us which joints will not collide. In the subsequent collision detection algorithm, you can directly skip the detection of these joints to improve the detection efficiency.
After the model is loaded, select [Self-Collisions] and click the [Generate Collision Matrix] button.
Adding a virtual joint can be understood as a joint that connects the robot and the world.
Virtual Joint Name We name it virtual_joint.
Child Link refers to the part of the robot that we want to connect the 'world' to. We choose the base base_link.
Parent Frame Name is the name of the world coordinates, which is generally called world in ROS.
Joint Type Select Fixed. This means that the robot is fixed relative to the world. The other two types, Planar, refer to the planar mobile base (xy plane + angle), used for mobile robots such as PR2; and Floating, refer to the floating base (xyz position + orientation), such as humanoid robots.
Create a motion planning group
Planning Group is one of the core functions of MoveIt. Click [Add Group] to add a planning group
Group Name: Create a group name and set it to [arm_group].
Kinematic Solver: Here we select [KDL]
Kinematic solver, which is responsible for solving forward kinematics and inverse kinematics (IK). Generally, we choose KDL, The Kinematics and Dynamics Library. This is a kinematics and dynamics library that can solve the forward and inverse kinematics problems of single-chain mechanical structures with more than 6 degrees of freedom.
Of course, you can also use other IK Solvers, such as SRV or IK_FAST, or even develop a new Solver yourself and insert it.
Kin. Search Resolution: Sampling density of joint space
Kin. Search TImeout: Solving time. If the device performance is insufficient or there is no solution within the specified time in the actual application process, the time can be increased; for example, set to [0.1], [0.01].
Click [Add Kin.Chain] to add a joint chain.
Click [Expand All], select Base Link as [base_link], select Tip Link as [6_Link]; click [save] to save.
Add a gripper planning group
Click [Add Group] to add a gripper planning group.
Set the creation group name to [gripper_group], and there is no need to set the kinematic solver; click [Add Links] to add the gripper link.
Select the connecting rod of the gripper part, click [>], automatically add the right side, and click [Save] to save.
Create preset poses
Select [Robot Poses] and click [Add pose] to add a pose.
Add the robot arm posture, and set the posture name Pose Name to [up].
Added [down] gesture
Added [init] gesture
Set the end effector joint
Select [End Effectors] and set it as shown below
Create a ROS controller
Select [ROS Control] and click to automatically add follow joint tracks
Add simulation
Select [Simulation], click [Generate URDF]
Add author information. If you don't add it, it won't be generated.
Select [Author Information] and add the following content.
Generate configuration files
Select [Configuration Files], click [Browse], select the folder you want to place it in (the folder must be empty), click the [Generate Package] button to generate the configuration file. When finished, click [Exit Setup Assistant]
4. Detailed explanation of MoveIt configuration package
Open the newly created [jetcobot_moveit_config] folder and we will find two folders: config and launch.
Config folder
fake_controllers.yaml: This is the virtual controller configuration file, which allows us to run MoveIt without a physical robot or even without any simulator (such as gazebo) turned on.
joint_limits.yaml: This records the position, velocity and acceleration limits of each joint of the robot, which will be used in future planning.
kinematics.yaml: Things set by the motion planning group, used to initialize the kinematics solution library
jetcobot.srdf: This is an important MoveIt configuration file.
ompl_planning.yaml: This is where various parameters of various OMPL algorithms are configured.
launch folder
demo.launch: demo is the summary point of the run. When we open it, we can see that it includes other launch files.
move_group.launch: As the name implies, the function of move group is to make a planning group move. The default is to use the ompl motion planning library. The others are to set some basic parameters, which can be skipped for now.
planning_context.launch: Here we can see that the urdf and srdf files used, as well as the kinematic solution library, are defined. It is not recommended to change these manually, but if you need to use different urdf, srdf, you can change them here.
setup_assistant.launch: If you need to change some configurations, you can run it directly.
5. Configuration validation
Enter the workspace where the configuration file is located and execute the following command
xxxxxxxxxxcd ~/jetcobot_ws/ # Enter the workspacecatkin_make # Compilesource devel/setup.bash # Update system environmentroslaunch jetcobot_moveit_config demo.launch# Start moveITAs shown below.
