Why can't I import custom message module in ROS?

edit

Hi, I'm a student studying ROS.

I want to use custom message. So, I searched some of materials, but it doesn't work.

Please help me...

this is error message.

process[both_of_motor-3]: started with pid [5985]
Traceback (most recent call last):
  File "/home/hs/catkin_ws2/src/motor/src/both_of_motor.py", line 5, in <module>
    from motor.msg import motor 
ImportError: No module named msg
[ERROR] [1613469949.149284]: Error opening serial: [Errno 2] could not open port /dev/ttyUSB0: [Errno 2] No such file or directory: '/dev/ttyUSB0'
[both_of_motor-3] process has died [pid 5985, exit code 1, cmd /home/hs/catkin_ws2/src/motor/src/both_of_motor.py __name:=both_of_motor __log:=/home/hs/.ros/log/8aa06470-703e-11eb-8ea6-f8a2d66c8c55/both_of_motor-3.log].

and below is source code.

  1 #!/usr/bin/env python
  2 # -*- coding: utf-8 -*-
  3 
  4 import rospy
  5 from motor.msg import motor
  6 
  7 angle = 90
  8 speed = 90
  9 
 10 def talker():
 11     global angle, speed
 12 
 13     pub = rospy.Publisher('motor', motor)
 14     rospy.init_node('motorControl', anonymous=True)
 15 
 16     msg = motor()
 17 
 18     while not rospy.is_shutdown():
 19         msg.angle = angle
 20         msg.speed = speed
 21 
 22         pub.publish(msg)
 23 
 24         angle += 10
 25         speed += 2
 26 
 27         rospy.sleep(2)
 28 
 29 
 30 if __name__ == '__main__':
 31     try:
 32         talker()
 33     except rospy.ROSInterruptException:
 34         pass

It is my directory structure.

├── motor
│   ├── CMakeLists.txt
│   ├── include
│   │   └── motor
│   ├── launch
│   │   ├── both_of_motor.launch
│   │   └── motor.launch
│   ├── msg
│   │   └── motor.msg
│   ├── package.xml
│   └── src
│       ├── both_of_motor.py
│       ├── .motor_pub.py.swp
│       ├── motor.py
│       └── motor.pyc

and it is my CMakeLists.txt

cmake_minimum_required(VERSION 3.0.2)
project(motor)

find_package(catkin REQUIRED COMPONENTS
  roscpp
  rospy
  std_msgs
  message_generation
)

## Generate messages in the 'msg' folder
add_message_files(
  FILES
  motor.msg
)

## Generate added messages and services with any dependencies listed here
generate_messages(
  DEPENDENCIES
  std_msgs
)
catkin_package(
#  INCLUDE_DIRS include
#  LIBRARIES motor
  CATKIN_DEPENDS roscpp rospy std_msgs
#  DEPENDS system_lib
)

include_directories(
# include
  ${catkin_INCLUDE_DIRS}
)

and it is package.xml

<?xml version="1.0"?>
<package format="2">
  <name>motor</name>
  <version>0.0.0</version>
  <description>The motor package</description>

  <maintainer email="hs@todo.todo">hs</maintainer>

  <license>TODO</license>

  <build_depend>message_generation</build_depend>
  <exec_depend>message_runtime</exec_depend>
  <buildtool_depend>catkin</buildtool_depend>
  <build_depend>roscpp</build_depend>
  <build_depend>rospy</build_depend>
  <build_depend>std_msgs</build_depend>
  <build_depend>message_generation</build_depend>
  <build_export_depend>roscpp</build_export_depend>
  <build_export_depend>rospy</build_export_depend>
  <build_export_depend>std_msgs</build_export_depend>
  <exec_depend>roscpp</exec_depend>
  <exec_depend>rospy</exec_depend>
  <exec_depend>std_msgs</exec_depend>
  <exec_depend>message_runtime</exec_depend>

</package>

next is $export | grep ROS

hs@hs-800G5H-800G5S:~/catkin_ws2/src/motor$ export | grep ROS
declare -x ROSLISP_PACKAGE_DIRECTORIES="/home/hs/catkin_ws2/devel/share/common-lisp"
declare -x ROS_DISTRO="melodic"
declare -x ROS_ETC_DIR="/opt/ros/melodic/etc/ros"
declare -x ROS_HOSTNAME="127.0.0.1"
declare -x ROS_MASTER_URI="http://127.0.0.1:11311"
declare -x ROS_PACKAGE_PATH="/home/hs/catkin_ws2/src:/opt/ros/melodic/share"
declare -x ROS_PYTHON_VERSION="2"
declare -x ROS_ROOT="/opt/ros/melodic/share/ros"
declare -x ROS_VERSION="1"

it is $ echo $PYTHONPATH

hs@hs-800G5H-800G5S:~/catkin_ws2/src/motor$ echo $PYTHONPATH
/home/hs/catkin_ws2/devel/lib/python2.7/dist-packages:/opt/ros/melodic/lib/python2.7/dist-packages

it is python -> sys.path

hs@hs-800G5H-800G5S:~/catkin_ws2/src/motor$ python
Python 2.7.17 (default, Sep 30 2020, 13:38:04) 
[GCC 7.5.0 ...