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基盤モデル×RoboticsAdvent Calendar 2022

Day 4

【後編】ChatGPTでロボットコード「PythonRobotics」を解読できるのか?

Last updated at Posted at 2022-12-03

はじめに

基盤モデル×RoboticsのAdventCalendarの4日目です!
カレンダーものぞいてみてくださいー!(私は計3投稿目らしい笑)
https://qiita.com/advent-calendar/2022/robot-ai
一日目に基盤モデルのお話を書いてますので、ぜひ!

拡散RT&いいね何卒です(モチベあがります!)

おさらい

本記事は【後編】ChatGPTでロボットコード「PythonRobotics」を解読できるのか?となり、前編があります!
以下から前編を良ければご覧ください!

【前編】ChatGPTでロボットのコード生成はできるのか?

ChatGPTとは

OpenAIが開発するGPT-3(※)という大規模言語モデルをベースとしたチャットアプリです。
実際のにどんな事ができるか見てみましょう!

ChatGPTに聞いてみよう!

ChatGPTにChatGPTについて聞く

Screenshot from 2022-12-03 07-18-34.png

ChatGPTにChatGPTのデメリットについて聞く

Screenshot from 2022-12-03 07-21-07.png

何ができるのか(返答がくるのか)?

沢山のユーザの報告により、以下ができるみたいです。

質問に対する応答
架空のものに対する返答
架空の食べ物のレシピ
料理やお菓子のレシピ(正確性については?)
特定の材料を指定してレシピや料理の提示
レシピの量の換算(1人前のレシピを3人前になど)
Wikipedia風の文章
お店の人気料理(有名店)
お店のメニュー(有名店)
シナリオのあらすじ
遊園地のおすすめアトラクション
要約
哲学的な質問への応答
特定の語尾にする
キャラクターの言いそうなこと、言わなそうなこと
タスクの作成
リストを文章化する
スケジュール
プログラミングコードの生成
DB設計

以下記事ともに、なんとなくChatGPTのイメージはついたでしょうか?
【前編】ChatGPTでロボットのコード生成はできるのか?


では、本題へいきましょう!

【後編】ChatGPTでロボットコード「PythonRobotics」を解読できるのか?

今回は、プログラミングコードの解読に着目しています。

コード与えて説明してくれたらめっちゃありがたいなあと思いまして。。。

結論

ほどほどに解読してくれた!!!!
衝撃!!!

いざ、本題へ!!!

PythonRoboticsのDWA:dynamic window approach(自律移動手法)を解読できるのか?

PythonRoboticsとは、Sakaiさんが開発している「ロボティクスの代表的な様々なアルゴリズムをPythonで実装したOSS」です。

PythonRoboticsについては以下を参考にしてください。

PythonRoboticsのDWA:dynamic window approach(自律移動手法)をChatGPTに解読を頼んでみた

DWA:dynamic window approach(自律移動手法)の動作例

以下の動画のように障害物を避けながら、ゴール地点へ向かう自律移動手法です。

animation.gif
gifの引用元

上の動作例のコードをいざChatGPTへ!

実際にいれてみた。。。。。。。

このリンクのコードを丁寧に説明してください。
https://github.com/AtsushiSakai/PythonRobotics/blob/master/PathPlanning/DynamicWindowApproach/dynamic_window_approach.py

実際のコード一部

"""
Mobile robot motion planning sample with Dynamic Window Approach
author: Atsushi Sakai (@Atsushi_twi), Göktuğ Karakaşlı
"""

import math
from enum import Enum

import matplotlib.pyplot as plt
import numpy as np

show_animation = True


def dwa_control(x, config, goal, ob):
    """
    Dynamic Window Approach control
    """
    dw = calc_dynamic_window(x, config)

    u, trajectory = calc_control_and_trajectory(x, dw, config, goal, ob)

    return u, trajectory


class RobotType(Enum):
    circle = 0
    rectangle = 1


class Config:
    """
    simulation parameter class
    """

    def __init__(self):
        # robot parameter
        self.max_speed = 1.0  # [m/s]
        self.min_speed = -0.5  # [m/s]
        self.max_yaw_rate = 40.0 * math.pi / 180.0  # [rad/s]
        self.max_accel = 0.2  # [m/ss]
        self.max_delta_yaw_rate = 40.0 * math.pi / 180.0  # [rad/ss]
        self.v_resolution = 0.01  # [m/s]
        self.yaw_rate_resolution = 0.1 * math.pi / 180.0  # [rad/s]
        self.dt = 0.1  # [s] Time tick for motion prediction
        self.predict_time = 3.0  # [s]
        self.to_goal_cost_gain = 0.15

どうなるのか・・・・・・・・・・・・・・・・・・・・・・

Screenshot from 2022-12-04 00-58-00.png

Screenshot from 2022-12-04 00-58-07.png

なんと!!!!!!!!!!!!!!!!!!!!!!!!!!
上記が解読結果です!!!!!!!!!!!!!!!!!!!!!!
ところどころ間違っている所もありますが、大方あっていますね!!!!!!!
これはすごいですね。。。言葉がでません。。。。

おわりに

お読み頂きありがとうございました!
引き続き、ご投稿「基盤モデル×Robotics」のAdvent Calendarへのご投稿もお待ちしております!!!(12/6)の人がまだいません。。。

本日は軽めの記事ですみませんが、今後共何卒よろしくお願いします!

拡散RT&いいね何卒です(モチベあがります!)

おまけ

Screenshot from 2022-12-04 01-09-07.png

DWA:dynamic window approachの改良手法

謝辞

PythonRobotics様に深く感謝を申し上げます。

参考コード(ChatGPTに入れたコード)

引用元:https://github.com/AtsushiSakai/PythonRobotics/blob/master/PathPlanning/DynamicWindowApproach/dynamic_window_approach.py


以下がDWAのpythonコードです。

"""
Mobile robot motion planning sample with Dynamic Window Approach
author: Atsushi Sakai (@Atsushi_twi), Göktuğ Karakaşlı
"""

import math
from enum import Enum

import matplotlib.pyplot as plt
import numpy as np

show_animation = True


def dwa_control(x, config, goal, ob):
    """
    Dynamic Window Approach control
    """
    dw = calc_dynamic_window(x, config)

    u, trajectory = calc_control_and_trajectory(x, dw, config, goal, ob)

    return u, trajectory


class RobotType(Enum):
    circle = 0
    rectangle = 1


class Config:
    """
    simulation parameter class
    """

    def __init__(self):
        # robot parameter
        self.max_speed = 1.0  # [m/s]
        self.min_speed = -0.5  # [m/s]
        self.max_yaw_rate = 40.0 * math.pi / 180.0  # [rad/s]
        self.max_accel = 0.2  # [m/ss]
        self.max_delta_yaw_rate = 40.0 * math.pi / 180.0  # [rad/ss]
        self.v_resolution = 0.01  # [m/s]
        self.yaw_rate_resolution = 0.1 * math.pi / 180.0  # [rad/s]
        self.dt = 0.1  # [s] Time tick for motion prediction
        self.predict_time = 3.0  # [s]
        self.to_goal_cost_gain = 0.15
        self.speed_cost_gain = 1.0
        self.obstacle_cost_gain = 1.0
        self.robot_stuck_flag_cons = 0.001  # constant to prevent robot stucked
        self.robot_type = RobotType.circle

        # if robot_type == RobotType.circle
        # Also used to check if goal is reached in both types
        self.robot_radius = 1.0  # [m] for collision check

        # if robot_type == RobotType.rectangle
        self.robot_width = 0.5  # [m] for collision check
        self.robot_length = 1.2  # [m] for collision check
        # obstacles [x(m) y(m), ....]
        self.ob = np.array([[-1, -1],
                            [0, 2],
                            [4.0, 2.0],
                            [5.0, 4.0],
                            [5.0, 5.0],
                            [5.0, 6.0],
                            [5.0, 9.0],
                            [8.0, 9.0],
                            [7.0, 9.0],
                            [8.0, 10.0],
                            [9.0, 11.0],
                            [12.0, 13.0],
                            [12.0, 12.0],
                            [15.0, 15.0],
                            [13.0, 13.0]
                            ])

    @property
    def robot_type(self):
        return self._robot_type

    @robot_type.setter
    def robot_type(self, value):
        if not isinstance(value, RobotType):
            raise TypeError("robot_type must be an instance of RobotType")
        self._robot_type = value


config = Config()


def motion(x, u, dt):
    """
    motion model
    """

    x[2] += u[1] * dt
    x[0] += u[0] * math.cos(x[2]) * dt
    x[1] += u[0] * math.sin(x[2]) * dt
    x[3] = u[0]
    x[4] = u[1]

    return x


def calc_dynamic_window(x, config):
    """
    calculation dynamic window based on current state x
    """

    # Dynamic window from robot specification
    Vs = [config.min_speed, config.max_speed,
          -config.max_yaw_rate, config.max_yaw_rate]

    # Dynamic window from motion model
    Vd = [x[3] - config.max_accel * config.dt,
          x[3] + config.max_accel * config.dt,
          x[4] - config.max_delta_yaw_rate * config.dt,
          x[4] + config.max_delta_yaw_rate * config.dt]

    #  [v_min, v_max, yaw_rate_min, yaw_rate_max]
    dw = [max(Vs[0], Vd[0]), min(Vs[1], Vd[1]),
          max(Vs[2], Vd[2]), min(Vs[3], Vd[3])]

    return dw


def predict_trajectory(x_init, v, y, config):
    """
    predict trajectory with an input
    """

    x = np.array(x_init)
    trajectory = np.array(x)
    time = 0
    while time <= config.predict_time:
        x = motion(x, [v, y], config.dt)
        trajectory = np.vstack((trajectory, x))
        time += config.dt

    return trajectory


def calc_control_and_trajectory(x, dw, config, goal, ob):
    """
    calculation final input with dynamic window
    """

    x_init = x[:]
    min_cost = float("inf")
    best_u = [0.0, 0.0]
    best_trajectory = np.array([x])

    # evaluate all trajectory with sampled input in dynamic window
    for v in np.arange(dw[0], dw[1], config.v_resolution):
        for y in np.arange(dw[2], dw[3], config.yaw_rate_resolution):

            trajectory = predict_trajectory(x_init, v, y, config)
            # calc cost
            to_goal_cost = config.to_goal_cost_gain * calc_to_goal_cost(trajectory, goal)
            speed_cost = config.speed_cost_gain * (config.max_speed - trajectory[-1, 3])
            ob_cost = config.obstacle_cost_gain * calc_obstacle_cost(trajectory, ob, config)

            final_cost = to_goal_cost + speed_cost + ob_cost

            # search minimum trajectory
            if min_cost >= final_cost:
                min_cost = final_cost
                best_u = [v, y]
                best_trajectory = trajectory
                if abs(best_u[0]) < config.robot_stuck_flag_cons \
                        and abs(x[3]) < config.robot_stuck_flag_cons:
                    # to ensure the robot do not get stuck in
                    # best v=0 m/s (in front of an obstacle) and
                    # best omega=0 rad/s (heading to the goal with
                    # angle difference of 0)
                    best_u[1] = -config.max_delta_yaw_rate
    return best_u, best_trajectory


def calc_obstacle_cost(trajectory, ob, config):
    """
    calc obstacle cost inf: collision
    """
    ox = ob[:, 0]
    oy = ob[:, 1]
    dx = trajectory[:, 0] - ox[:, None]
    dy = trajectory[:, 1] - oy[:, None]
    r = np.hypot(dx, dy)

    if config.robot_type == RobotType.rectangle:
        yaw = trajectory[:, 2]
        rot = np.array([[np.cos(yaw), -np.sin(yaw)], [np.sin(yaw), np.cos(yaw)]])
        rot = np.transpose(rot, [2, 0, 1])
        local_ob = ob[:, None] - trajectory[:, 0:2]
        local_ob = local_ob.reshape(-1, local_ob.shape[-1])
        local_ob = np.array([local_ob @ x for x in rot])
        local_ob = local_ob.reshape(-1, local_ob.shape[-1])
        upper_check = local_ob[:, 0] <= config.robot_length / 2
        right_check = local_ob[:, 1] <= config.robot_width / 2
        bottom_check = local_ob[:, 0] >= -config.robot_length / 2
        left_check = local_ob[:, 1] >= -config.robot_width / 2
        if (np.logical_and(np.logical_and(upper_check, right_check),
                           np.logical_and(bottom_check, left_check))).any():
            return float("Inf")
    elif config.robot_type == RobotType.circle:
        if np.array(r <= config.robot_radius).any():
            return float("Inf")

    min_r = np.min(r)
    return 1.0 / min_r  # OK


def calc_to_goal_cost(trajectory, goal):
    """
        calc to goal cost with angle difference
    """

    dx = goal[0] - trajectory[-1, 0]
    dy = goal[1] - trajectory[-1, 1]
    error_angle = math.atan2(dy, dx)
    cost_angle = error_angle - trajectory[-1, 2]
    cost = abs(math.atan2(math.sin(cost_angle), math.cos(cost_angle)))

    return cost


def plot_arrow(x, y, yaw, length=0.5, width=0.1):  # pragma: no cover
    plt.arrow(x, y, length * math.cos(yaw), length * math.sin(yaw),
              head_length=width, head_width=width)
    plt.plot(x, y)


def plot_robot(x, y, yaw, config):  # pragma: no cover
    if config.robot_type == RobotType.rectangle:
        outline = np.array([[-config.robot_length / 2, config.robot_length / 2,
                             (config.robot_length / 2), -config.robot_length / 2,
                             -config.robot_length / 2],
                            [config.robot_width / 2, config.robot_width / 2,
                             - config.robot_width / 2, -config.robot_width / 2,
                             config.robot_width / 2]])
        Rot1 = np.array([[math.cos(yaw), math.sin(yaw)],
                         [-math.sin(yaw), math.cos(yaw)]])
        outline = (outline.T.dot(Rot1)).T
        outline[0, :] += x
        outline[1, :] += y
        plt.plot(np.array(outline[0, :]).flatten(),
                 np.array(outline[1, :]).flatten(), "-k")
    elif config.robot_type == RobotType.circle:
        circle = plt.Circle((x, y), config.robot_radius, color="b")
        plt.gcf().gca().add_artist(circle)
        out_x, out_y = (np.array([x, y]) +
                        np.array([np.cos(yaw), np.sin(yaw)]) * config.robot_radius)
        plt.plot([x, out_x], [y, out_y], "-k")


def main(gx=10.0, gy=10.0, robot_type=RobotType.circle):
    print(__file__ + " start!!")
    # initial state [x(m), y(m), yaw(rad), v(m/s), omega(rad/s)]
    x = np.array([0.0, 0.0, math.pi / 8.0, 0.0, 0.0])
    # goal position [x(m), y(m)]
    goal = np.array([gx, gy])

    # input [forward speed, yaw_rate]

    config.robot_type = robot_type
    trajectory = np.array(x)
    ob = config.ob
    while True:
        u, predicted_trajectory = dwa_control(x, config, goal, ob)
        x = motion(x, u, config.dt)  # simulate robot
        trajectory = np.vstack((trajectory, x))  # store state history

        if show_animation:
            plt.cla()
            # for stopping simulation with the esc key.
            plt.gcf().canvas.mpl_connect(
                'key_release_event',
                lambda event: [exit(0) if event.key == 'escape' else None])
            plt.plot(predicted_trajectory[:, 0], predicted_trajectory[:, 1], "-g")
            plt.plot(x[0], x[1], "xr")
            plt.plot(goal[0], goal[1], "xb")
            plt.plot(ob[:, 0], ob[:, 1], "ok")
            plot_robot(x[0], x[1], x[2], config)
            plot_arrow(x[0], x[1], x[2])
            plt.axis("equal")
            plt.grid(True)
            plt.pause(0.0001)

        # check reaching goal
        dist_to_goal = math.hypot(x[0] - goal[0], x[1] - goal[1])
        if dist_to_goal <= config.robot_radius:
            print("Goal!!")
            break

    print("Done")
    if show_animation:
        plt.plot(trajectory[:, 0], trajectory[:, 1], "-r")
        plt.pause(0.0001)

    plt.show()


if __name__ == '__main__':
    main(robot_type=RobotType.rectangle)
    # main(robot_type=RobotType.circle)
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