About | Support | Discussion Forum | Index | Service Status | ros @ Robotics Stack Exchange

Only released in EOL distros:   indigo

The nj_oa_costmap package implements a navigating jockey for the Large Maps Framework (LaMa) that drives the robot while avoiding obstacles. It is based on a local map (nav_msgs/OccupancyGrid). The local map has a fixed position relative to the robot but its orientation is constant in the world reference frame. It is a reactive, memory-less jockey.

Implemented action:

• TRAVERSE: go more or less forward depending on obstacle position. The action never stops by itself.
• STOP: stop the robot, sending this action is the only way to stop a TRAVERSE action.
• INTERRUPT: same as STOP
• CONTINUE: same as TRAVERSE

Moreover, the package provides the class TwistHandler that computes an appropriate geometry_msgs/Twist from a nav_msgs/OccupancyGrid in order to go as forward as possible while avoiding obstacles.

Usage

ROS API

Subscribed Topics

~<name>/local_map (nav_msgs/OccupancyGrid)

• local map with fixed position relative to the robot and fixed orientation relative to the world reference frame

Published Topics

~<name>/cmd_vel (geometry_msgs/Twist)

• set velocity

Parameters

~<name>/robot_radius (Float)

• robot radius (m)

~<name>/min_distance (Float, default: 2 * robot_radius)

• if an obstacle is closer than this, turn and don't go forward (m)

~<name>/long_distance (Float, default: 5 * robot_radius)

• if no obstacle within this distance, go straight (m)

~<name>/turnrate_collide (Float, default: 0.4)

• turn rate when obstacle closer than ~min_distance_ (rad/s)

~<name>/max_vel (Float, default: 1.0)

• linear velocity without obstacle (m/s)

~<name>/vel_close_obstacle (Float, default: 0.5)

• linear velocity if obstacle between min_distance and long_distance (m/s)

~<name>/turnrate_factor (Float, default: 0.9)

• if obstacle closer than ~long_distance, turnrate = -turnrate_factor_ * mean(lateral_position_of_obstacle) (rad.m^-1.s-1).

~<name>/laser_frame (String, default: "base_laser_link")

• frame_id of the laser scan messages that are used to build the local map.

~<name>/navigating_jockey_server_name (String, default: node_name + "_server")

• Jockey name