The map_follower is a ROS package for autonomous navigation and control of an ackermann steered race car. The software takes 2D lidar data and IMU to localise itself on a given map and race along a predefined trajectory.
The software is tested on UBUNTU 16.04 with ROS Kinetic.
The software is a standard catkin package. Make sure the package is on ROS_PACKAGE_PATH after cloning the package to your workspace.
cd your_work_space
catkin_make
The hardware used to development of this package is a 1/10th scaled rally racing car. It comprises of Nvidia Jetson and the main computer and Arduino UNO as the lowlevel controller. The car uses a Hukoyu 2D lidar and an 6DOF IMU.
The control can be divide into two main parts localization and navigation. The code uses Adaptive Monte Carlo Localization(AMCL), this though very accurate runs at approximately 4Hz and its reliability is heavily dependent on availability of distinct features.
For continous tracking of the vehicle we combine this with model predicition and IMU.
Model prediction uses the acceleration and velocity model to estimate its position and IMU uses double integrator. Both these run at 150Hz.
For tracking all there values are fused.
The code consists of two PD control loops which run at 150Hz. The setpoint for both these loops in the waypoint in consideration. The waypoint in consideration is updated from the CSV file at 1.2 Hz. the first control loop control the forward velocity acting based in how far the waypoint is(x-direction) and the second control loop controls the steering angle depending on the y error.
The waypoints marked by the user are in map_frame and the IMU readings obtained are in car_frame, we thus transform the "waypoint in consideration" as per the location of the car. This makes it easier to fuse the IMU values.
The above is a matlab script which simulates a PD controlled ackermann steered vehicle. This script can be used to understand and visualize how and which paramters to change.
Upload hallmap.pgm and hallmap.yaml in the resource folder.
Update hallmap.launch with the address of hallmap.yaml file.
Launch map
roslaunch map_follower hallmap.launch
Run the waypoint.py for waypoint generation.
rosrun map_follower waypoint.py
This script allows the user to use rviz for selecting waypoints, visualize the path and save the waypoints in a CSV file.
In a new terminal execute the run.py file
rosrun map_follower run.py
