Moveit State Server

The ROS package moveit_state_server offers services to store the current joint angles or the end effector position ( for example, in the world frame). Later the robot can return to the saved state. For this purpose, the state is given a unique name when it is saved via a ROS service. Later an action client, which moves to the stored position using moveit, can be called with the assigned name. The package uses the moveit_cpp functionality to access the current state and control the robot.

Moreover, the node can store the joint states persistently in a database. Therefore, it makes use of the mongo database included in moveit_warehouse. Configured correctly, it stores the joint states in the same database as the moveit motion planning rviz plugin. Alternatively, the joint states can be persistently stored by saving them as serialized sensor_msgs/JointState. The parameter database_instead_of_filestorage in the moveit_state_server.launch file decides which persistent joint state storage is used.

Launching

If you want to make use of persistently storing joint states in the database, the mongo database must be running. This can be done by selecting the db param while launching moveit , see moveit documentation: Persistent States . Alternatively, the database can be launched by setting launch_database in the moveit_state_server.launch to true or launch the database.launch file in the moveit_state_server package directly. If using the moveit launch file, make sure to select the mongo database plugin and selecting the same port and hostname as in the launch file for the moveit state server.

roslaunch moveit_state_server database.launch

Launching the moveit_state_server can be done with

roslaunch moveit_state_server moveit_state_server.launch

Storing joint states / end-effector poses

The service /store_arm_poses stores either the current joint angles or the end-effector pose depending on the selected mode. Additionally, the user must provide a name for the stored state.

Service Message Description: Store state

int32 mode
string name
int32 STORE_JOINT_POSITIONS=0
int32 STORE_END_EFFECTOR_POSE=1
---
std_msgs/Bool success

Note that storing the end-effector pose persistently is not very useful because after restarting the robot the coordinate system will be different. Hence, only the joint states are stored persistently.

Retrieving stored joint states / end-effector poses

The service /retrieve_arm_poses can be used to retrieve a stored joint_state or end-effector pose.

Service Message Description: Retrieve state

int32 mode
int32 RETRIEVE_JOINT_POSITIONS=0
int32 RETRIEVE_END_EFFECTOR_POSE=1
string name
---
sensor_msgs/JointState joint_state
geometry_msgs/PoseStamped pose

Moving the robot to a stored state

The action client /move_arm_to_stored_pose can be used to move the robot such that it is again in a previously stored state. The goal message defines the type and name of the goal

Action Message Description: Move arm

int32 mode
string name
int32 GO_TO_STORED_JOINT_POSITIONS=0
int32 GO_TO_STORED_END_EFFECTOR_POSE=1
---
int32 success
---
int32 state

Requirements

This ROS package requires moveit, see here, to be installed

If you want to store states persistently with the database, the warehouse-ros-mongo package must be installed.

sudo apt install ros-noetic-warehouse-ros-mongo

Contributing

If you find a bug or would like to contribute to this ROS package, please open an issue on the Github repository or submit a pull request.