Accel Brake Map Calibrator#

The role of this node is to automatically calibrate accel_map.csv / brake_map.csv used in the raw_vehicle_cmd_converter node.

The base map, which is lexus's one by default, is updated iteratively with the loaded driving data.

How to calibrate#

Launch Calibrator#

After launching Autoware, run the accel_brake_map_calibrator by the following command and then perform autonomous driving. Note: You can collect data with manual driving if it is possible to use the same vehicle interface as during autonomous driving (e.g. using a joystick).

ros2 launch accel_brake_map_calibrator accel_brake_map_calibrator.launch.xml rviz:=true

Or if you want to use rosbag files, run the following commands.

ros2 param set /use_sim_time true
ros2 bag play <rosbag_file> --clock

During the calibration with setting the parameter progress_file_output to true, the log file is output in [directory of accel_brake_map_calibrator]/config/ . You can also see accel and brake maps in [directory of accel_brake_map_calibrator]/config/accel_map.csv and [directory of accel_brake_map_calibrator]/config/brake_map.csv after calibration.

Calibration plugin#

The rviz:=true option displays the RViz with a calibration plugin as below.

The current status (velocity and pedal) is shown in the plugin. The color on the current cell varies green/red depending on the current data is valid/invalid. The data that doesn't satisfy the following conditions are considered invalid and will not be used for estimation.

The velocity and pedal conditions are within certain ranges from the index values.
The steer value, pedal speed, pitch value, etc. are less than corresponding thresholds.
The velocity is higher than a threshold.

Note: You don't need to worry about whether the current state is red or green during calibration. Just keep getting data until all the cells turn red.

The value of each cell in the map is gray at first, and it changes from blue to red as the number of valid data in the cell accumulates. It is preferable to continue the calibration until each cell of the map becomes close to red. In particular, the performance near the stop depends strongly on the velocity of 0 ~ 6m/s range and the pedal value of +0.2 ~ -0.4, range so it is desirable to focus on those areas.

Check the recommended notifications for map updates#

ros2 topic echo /accel_brake_map_calibrator/output/update_suggest

(It is desirable to monitor this topic while driving)

If true, the map was updated correctly. If false, not correctly.

Error evaluation of the accel / brake map#

The error of map is evaluated by the Root Mean Squared Error (RMSE) between the observed acceleration and predicted acceleration.

TERMS:

Observed acceleration: the current vehicle acceleration which is calculated as a derivative value of the wheel speed.

Predicted acceleration: the output of the original accel/brake map, which the Autoware is expecting. The value is calculated using the current pedal and velocity.

You can check additional error information with the following topics.

/accel_brake_map_calibrator/output/current_map_error : The error of the original map set in the csv_path_accel/brake_map path. The original map is not accurate if this value is large.
/accel_brake_map_calibrator/output/updated_map_error : The error of the map calibrated in this node. The calibration quality is low if this value is large.
/accel_brake_map_calibrator/output/map_error_ratio : The error ratio between the original map and updated map (ratio = updated / current). If this value is less than 1, it is desirable to update the map.

How to visualize calibration data#

The process of calibration can be visualized as below. Since these scripts need the log output of the calibration, the pedal_accel_graph_output parameter must be set to true while the calibration is running for the visualization.

Visualize plot of relation between acceleration and pedal#

The following command shows the plot of used data in the calibration. In each plot of velocity ranges, you can see the distribution of the relationship between pedal and acceleration, and raw data points with colors according to their pitch angles.

ros2 run accel_brake_map_calibrator view_plot.py

sample pic

Visualize statistics about acceleration/velocity/pedal data#

The following command shows the statistics of the calibration:

mean value
standard deviation
number of data

of all data in each map cell.

ros2 run accel_brake_map_calibrator view_statistics.py

sample pic2

How to save the calibrated accel / brake map anytime you want#

You can save accel and brake map anytime with the following command.

ros2 service call /accel_brake_map_calibrator/update_map_dir "path: '<accel/brake map directory>'"

You can also save accel and brake map in the default directory where Autoware reads accel_map.csv/brake_map.csv using the RViz plugin (AccelBrakeMapCalibratorButtonPanel) as following.

Click Panels tab, and select AccelBrakeMapCalibratorButtonPanel.
Select the panel, and the button will appear at the bottom of RViz.
Press the button, and the accel / brake map will be saved. (The button cannot be pressed in certain situations, such as when the calibrator node is not running.)

Parameters#

Name	Type	Description	Default value
update_method	string	you can select map calibration method. "update_offset_each_cell" calculates offsets for each grid cells on the map. "update_offset_total" calculates the total offset of the map.	"update_offset_each_cell"
get_pitch_method	string	"tf": get pitch from tf, "none": unable to perform pitch validation and pitch compensation	"tf"
pedal_accel_graph_output	bool	if true, it will output a log of the pedal accel graph.	true
progress_file_output	bool	if true, it will output a log and csv file of the update process.	false
default_map_dir	str	directory of default map	[directory of raw_vehicle_cmd_converter]/data/default/
calibrated_map_dir	str	directory of calibrated map	[directory of accel_brake_map_calibrator]/config/