generate_motion_primitives.py

# Copyright (c) 2021, Matthew Booker
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License. Reserved.
 
import argparse
from datetime import datetime
import json
import logging
from pathlib import Path
import time
 
import constants
from lattice_generator import LatticeGenerator
 
import matplotlib.pyplot as plt
import numpy as np
 
 
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)
 
 
def handle_arg_parsing():
    """
    Handle the parsing of arguments.
 
    Returns
    -------
    argparse.Namespace
        An object containing all parsed arguments
 
    """
    parser = argparse.ArgumentParser(description='Generate motionprimitives '
                                                 "for Nav2's State "
                                                 'Lattice Planner')
    parser.add_argument('--config',
                        type=Path,
                        default='./config.json',
                        help='The config file containing the '
                        'parameters to be used')
    parser.add_argument('--output',
                        type=Path,
                        default='./output.json',
                        help='The output file containing the '
                        'trajectory data')
    parser.add_argument('--visualizations',
                        type=Path,
                        default='./visualizations',
                        help='The output folder where the '
                        'visualizations of the trajectories will be saved')
 
    return parser.parse_args()
 
 
def create_heading_angle_list(minimal_set_trajectories: dict) -> list:
    """
    Create a sorted list of heading angles from the minimal trajectory set.
 
    Args:
    ----
    minimal_set_trajectories: dict
        The minimal spanning set
 
    Returns
    -------
    list
        A sorted list of heading angles
 
    """
    heading_angles = set(minimal_set_trajectories.keys())
    return sorted(heading_angles, key=lambda x: (x < 0, x))
 
 
def read_config(config_path) -> dict:
    """
    Read in the user defined parameters via JSON.
 
    Args:
    ----
    config_path: Path
        Path to the config file
 
    Returns
    -------
    dict
        Dictionary containing the user defined parameters
 
    """
    with open(config_path) as config_file:
        config = json.load(config_file)
 
    return config
 
 
def create_header(config: dict, minimal_set_trajectories: dict) -> dict:
    """
    Create a dict containing all the fields to populate the header with.
 
    Args:
    ----
    config: dict
        The dict containing user specified parameters
    minimal_set_trajectories: dict
        The minimal spanning set
 
    Returns
    -------
    dict
        A dictionary containing the fields to populate the header with
 
    """
    header_dict = {
        'version': constants.VERSION,
        'date_generated': datetime.today().strftime('%Y-%m-%d'),
        'lattice_metadata': {},
        'primitives': [],
    }
 
    for key, value in config.items():
        header_dict['lattice_metadata'][key] = value
 
    heading_angles = create_heading_angle_list(minimal_set_trajectories)
    adjusted_heading_angles = [angle + 2*np.pi if angle < 0 else angle for angle in heading_angles]
 
    header_dict['lattice_metadata']['heading_angles'] = adjusted_heading_angles
 
    return header_dict
 
 
def write_to_json(output_path: Path, minimal_set_trajectories: dict, config: dict) -> None:
    """
    Write the minimal spanning set to an output file.
 
    Args:
    ----
    output_path: Path
        The output file for the json data
    minimal_set_trajectories: dict
        The minimal spanning set
    config: dict
        The dict containing user specified parameters
 
    """
    output_dict = create_header(config, minimal_set_trajectories)
 
    trajectory_start_angles = list(minimal_set_trajectories.keys())
 
    heading_angle_list = create_heading_angle_list(minimal_set_trajectories)
    heading_lookup = {angle: idx for idx, angle in
                      enumerate(heading_angle_list)}
 
    idx = 0
    for start_angle in sorted(trajectory_start_angles,
                              key=lambda x: (x < 0, x)):
 
        for trajectory in sorted(
            minimal_set_trajectories[start_angle],
            key=lambda x: x.parameters.end_angle
        ):
 
            traj_info = {}
            traj_info['trajectory_id'] = idx
            traj_info['start_angle_index'] = heading_lookup[trajectory.parameters.start_angle]
            traj_info['end_angle_index'] = heading_lookup[trajectory.parameters.end_angle]
            traj_info['left_turn'] = bool(trajectory.parameters.left_turn)
            traj_info['trajectory_radius'] = \
                trajectory.parameters.turning_radius
            traj_info['trajectory_length'] = round(
                trajectory.parameters.total_length, 5
            )
            traj_info['arc_length'] = round(
                trajectory.parameters.arc_length,
                5
            )
            traj_info['straight_length'] = round(
                trajectory.parameters.start_straight_length
                + trajectory.parameters.end_straight_length,
                5,
            )
            traj_info['poses'] = trajectory.path.to_output_format()
 
            output_dict['primitives'].append(traj_info)
            idx += 1
 
    output_dict['lattice_metadata']['number_of_trajectories'] = idx
 
    with open(output_path, 'w') as output_file:
        json.dump(output_dict, output_file, indent='\t')
 
 
def save_visualizations(visualizations_folder: Path, minimal_set_trajectories: dict) -> None:
    """
    Draw the visualizations for every trajectory and save it as an image.
 
    Args:
    ----
    visualizations_folder: Path
        The path to the folder for where to save the images
    minimal_set_trajectories: dict
        The minimal spanning set
 
    """
    # Create the directory if it doesnt exist
    visualizations_folder.mkdir(exist_ok=True)
 
    for start_angle in minimal_set_trajectories.keys():
 
        for trajectory in minimal_set_trajectories[start_angle]:
            plt.plot(trajectory.path.xs, trajectory.path.ys, 'b')
 
    plt.grid(True)
    plt.axis('square')
    left_x, right_x = plt.xlim()
    left_y, right_y = plt.ylim()
 
    output_path = visualizations_folder / 'all_trajectories.png'
    plt.savefig(output_path)
    plt.clf()
 
    for start_angle in minimal_set_trajectories.keys():
 
        angle_in_deg = np.rad2deg(start_angle)
 
        if start_angle < 0 or start_angle > np.pi / 2:
            continue
 
        for trajectory in minimal_set_trajectories[start_angle]:
            plt.plot(trajectory.path.xs, trajectory.path.ys, 'b')
            plt.xlim(left_x, right_x)
            plt.ylim(left_y, right_y)
 
        plt.grid(True)
 
        output_path = visualizations_folder / f'{angle_in_deg}.png'
        plt.savefig(output_path)
        plt.clf()
 
 
if __name__ == '__main__':
 
    args = handle_arg_parsing()
    config = read_config(args.config)
 
    start = time.time()
    lattice_gen = LatticeGenerator(config)
    minimal_set_trajectories = lattice_gen.run()
    print(f'Finished Generating. Took {time.time() - start} seconds')
 
    write_to_json(args.output, minimal_set_trajectories, config)
    save_visualizations(args.visualizations, minimal_set_trajectories)