UML – go to point PY node

SCHEMA

@startuml ''' INFOS title NODE go_to_point skinparam Padding 8 allow_mixing ''' COMPONENTS database "ROS parameter server" as PARAMETERS { node "des_pos_x" node "des_pos_y" } component "go_to_point_service" <<ROSPy node>> as NODE_GO_TO_POINT { node "go_to_point_switch" as NODE_GO_TO_POINT.GOTOPOINT_SWITCH node "clbk_odom" as NODE_GO_TO_POINT.READ_ODOM } NODE_GO_TO_POINT "get" <-- PARAMETERS () "/cmd_vel" as TOPIC_VEL NODE_GO_TO_POINT "pub" --> TOPIC_VEL note on link: geometry_msgs/Twist.msg () "/odom" as TOPIC_ODOM NODE_GO_TO_POINT.READ_ODOM "sub" <-- TOPIC_ODOM note on link: nav_msgs/Odometry.msg () "/go_to_point_switch" as SRV_GOTO_SWITCH NODE_GO_TO_POINT.GOTOPOINT_SWITCH "srv" --> SRV_GOTO_SWITCH note on link: std_srvs/SetBool.srv @enduml

HOW it works

the node can be used only when there’s no obstacle between the robot and the target to reach. here’s how it works:

  • turn the head of the robot and orient it towards the target

  • go straight until the target hasn’t been reached

HOW TO use the node – basic way

it requires another node listening for the odom channel and checking when to deactivate the service

  • set des_pos_x and des_pos_y into the paramater server

  • activate the service with a request to /go_to_point_switch of type std_srvs/SetBool (flag SetBool.Request.data=True)

  • … wait until the robot is near enough to the point

  • turn off the node (flag SetBool.Request.data=False)