如何使用 ROS 导入自定义 python 模块？

Question

In side simulator.py, I'd imported PID.py from Control which is valid according to PyCharm IDE.

Program Structure:

src
├── quantum_drone
│   ├── CMakeLists.txt
│   ├── Control
│   │   ├── __init__.py
│   │   ├── Keys.py
│   │   ├── MonotonicTime.py
│   │   └── PID.py
│   ├── package.xml
│   └── scripts
│       ├── __init__.py
│       └── simulator.py

I realized I didn't have setup.py setup in my root directory (quantum_drone), so I when and set it up:

#!/usr/bin/env python
# noinspection PyUnresolvedReferences
from distutils.core import setup
from catkin_pkg.python_setup import generate_distutils_setup
   
# fetch values from package.xml
setup_args = generate_distutils_setup(
     packages=['quantum_drone'],
     scripts=['Control', 'scripts'],
     package_dir={'': 'src'},
 )
 
setup(**setup_args)

In my CMakeLists.txt, I had uncommented the catkin_python_setup() and inside catkin_install_python I wrote:

catkin_install_python(PROGRAMS
   scripts/simulator.py
   Control/PID.py
   DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
)

Finally, I ran:

catkin_make 
source devel/setup.bash

I try to run: rosrun quantum_drone simulator.py

But I keep getting this message:

Traceback (most recent call last):
  Traceback (most recent call last):
  File "/home/kannachan/drone/src/quantum_drone/scripts/simulator.py", line 3, in <module>
    from Control import PID
ImportError: No module named Control

I could've swore I did everything I needed to do, so I'm not sure where I when wrong such that I couldn't import my files/directories.

Contents of PID.py (I can import MonotonicTime.py just fine):

#!/usr/bin/env python

from pymavlink import mavutil
from MonotonicTime import monotonic_time
import numpy as np

current_time = monotonic_time


class PID:

    def __init__(self, vehicle, kp=0, ki=0, kd=0, velocity=(0, 0, 0)):
        self.kp = kp  # Constants (kp, ki, kd)
        self.ki = ki
        self.kd = kd
        self.drone = vehicle
        self.p_terms = np.array([0, 0, 0], dtype=float)  # 3-axis
        self.i_terms = np.array([0, 0, 0], dtype=float)
        self.d_terms = np.array([0, 0, 0], dtype=float)
        self.velocity = np.asarray(velocity)  # Desired Velocity
        self.current_velocity = np.array(self.drone.velocity)  # Current Velocity
        self.errors = np.array([0, 0, 0], dtype=float)  # Previous Error
        self.time = current_time()  # Current Time
        self.__max__ = 40  # Max Speed
        self.__min__ = 0  # Min Speed

    def reset(self):
        #  Resetting terms
        self.p_terms = np.array([0, 0, 0], dtype=float)
        self.i_terms = np.array([0, 0, 0], dtype=float)
        self.d_terms = np.array([0, 0, 0], dtype=float)
        self.errors = np.array([0, 0, 0], dtype=float)

    def calculate_change(self):
        now = current_time()
        delta_error = self.velocity - self.current_velocity  # Change in error
        delta_time = now - self.time if now - self.time else 1e-16  # Change in time
        self.time = now
        return delta_error, delta_time

    def pid_calculation(self):
        delta_error, delta_time = self.calculate_change()
        # PID controller formula
        self.p_terms = delta_error * self.kp
        self.i_terms += self.errors * delta_time
        self.d_terms = (delta_error - self.errors) / delta_time
        self.errors = delta_error
        outputs = self.kp * self.p_terms + self.ki * self.i_terms + self.kd * self.d_terms
        outputs = np.where(outputs > self.__max__, self.__max__, outputs)  # Replacing terms too big
        outputs = np.where(outputs < self.__min__, self.__min__, outputs)  # Replacing terms too small
        return outputs

    def send_command(self):
        vx, vy, vz = self.pid_calculation()
        msg = self.drone.message_factory.set_position_target_location_ned_encode(
            0,
            0, 0,
            mavutil.mavlink.MAV_FRAME_BODY_NED,
            0b0000111111000111,
            0, 0, 0,
            vx, vy, vz,
            0, 0
        )
        self.drone.send_mavlink(msg)
        self.drone.flush()

Answer 1

Your import is wrong. It should be importing from PID not Control. As well, within ROS1 you don't need a setup.py file for a Python package.