Our Mini-Challenge 2 solutions are stored in the 'puzzlebot_control' ROS2 package directory.
Inside, we created a node with a robust open loop controller implemented as a state machine called square_path_ctrl that enables a Puzzlebot differential drive robot to drive a square path of a side length of 2 meters.
Additionally, another node was created named path_generator which generates different paths according to a user. The paths are defined in the /config/params.yaml YAML file by different points, velocities or times. For each point, the node estimates the linear and rotational speeds in case a time is given by the user in the file or estimate the time in case the velocities are provided. It also lets the user know if the point is reachable according to the dynamical behavior of the mobile robot and the parameters of the user. The node then passes the information to an open_loop_path_ctrl node via the /pose topic so it can send a velocity to the Puzzlebot via the cmd_vel topic.
To select a path for the robot to make, please view the YAML file in /config/params.yaml and locate your path of interest. If the path ends with '_time it has defined times for each point. Meanwhile, if it ends with '_speed it has defined speeds for each point. After selecting a path, substitute the value that default_value has inside the path_arg argument for path selection in the path_generator_launch.py launch file:
def generate_launch_description():
# 1. Argument to select the path
path_arg = DeclareLaunchArgument(
'path_name',
default_value='square_path_speed', # Value to replace for path desired
description='Name of the path (e.g., figure_8_path_time, square_path_speed)'
)
To run the path_generator node and the open_loop_path_ctrl controller node, run the following command after running colcon_build and sourcing with source install/setup.bash:
ros2 launch puzzlebot_control path_generator_launch.py