无人车系统（九）：基于ROS与Gazebo的无人驾驶仿真环境——car_demo

在car_demo|无人车仿真环境全教程介绍了在系统：Ubuntu 14.04 indigo中安装配置car_demo。由于当时的电脑中的ubuntu与ros版本较低，我按照原教程的配置方法，安装Docker，nvidia-docker2，还有rocker。最终实现的是，让car_demo在独立的docker环境下运行，利用ROS的多机通信的机制配置（如何配置请参见car_demo|无人车仿真环境全教程），使得在自己电脑上能够与仿真环境进行数据交互。但是，这个过程真的好麻烦，使用感觉极为不佳。最近正好换了电脑，索性直接把系统换到ubuntu 18.04+ ros melodic。发现直接在本地编译能通过，之后就是本地的一个ros package，这样使用就方便多了。

系统： ubuntu 18.04+ros melodic
目的：配置car_demo无人车仿真环境

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安装与配置过程

• git clone car_demo项目到本地：

cd ~/Downloads
git clone https://github.com/osrf/car_demo.git

• 建立并定位到新工作空间，或已有工作空间~/cardemo_ws，这个位置与名字无所谓：

mkdir -p ~/cardemo_ws/src

• 将对应包复制到新建的工作空间的src目录下：

cd ~/Downloads/car_demo_master 
cp -r prius_description ~/cardemo_ws/src/prius_description
cp -r prius_msgs ~/cardemo_ws/src/prius_msgs
cp -r car_demo ~/cardemo_ws/src/car_demo

• 编译:

cd ~/cardemo_ws
catkin_make

• 添加环境

echo "source ～/cardemo_ws/devel/setup.bash" >> ~/.bashrc
source ~/.bashrc

简单测试

roslaunch car_demo demo.launch 

我们会看到RVIZ与Gazebo两个界面

• RVIZ
  
• Gazebo
  
• 查看topic数据(有激光、声呐、相机、车自身状态等数据)：

rostopic list

/amcl_pose
/base_pose_ground_truth
/clicked_point
/clock
/diagnostics
/gazebo/link_states
/gazebo/model_states
/gazebo/parameter_descriptions
/gazebo/parameter_updates
/gazebo/set_link_state
/gazebo/set_model_state
/initialpose
/joint_states
/joy
/joy/set_feedback
/move_base_simple/goal
/particlecloud
/prius   # 控制车的topic，包括刹车、油门、档位、方向盘转向等命令
/prius/back_camera/camera_info
/prius/back_camera/image_raw
/prius/back_camera/image_raw/compressed
/prius/back_camera/image_raw/compressed/parameter_descriptions
/prius/back_camera/image_raw/compressed/parameter_updates
/prius/back_camera/image_raw/compressedDepth
/prius/back_camera/image_raw/compressedDepth/parameter_descriptions
/prius/back_camera/image_raw/compressedDepth/parameter_updates
/prius/back_camera/image_raw/theora
/prius/back_camera/image_raw/theora/parameter_descriptions
/prius/back_camera/image_raw/theora/parameter_updates
/prius/back_camera/parameter_descriptions
/prius/back_camera/parameter_updates
/prius/back_sonar/left_far_range
/prius/back_sonar/left_middle_range
/prius/back_sonar/right_far_range
/prius/back_sonar/right_middle_range
/prius/center_laser/scan
/prius/front_camera/camera_info
/prius/front_camera/image_raw
/prius/front_camera/image_raw/compressed
/prius/front_camera/image_raw/compressed/parameter_descriptions
/prius/front_camera/image_raw/compressed/parameter_updates
/prius/front_camera/image_raw/compressedDepth
/prius/front_camera/image_raw/compressedDepth/parameter_descriptions
/prius/front_camera/image_raw/compressedDepth/parameter_updates
/prius/front_camera/image_raw/theora
/prius/front_camera/image_raw/theora/parameter_descriptions
/prius/front_camera/image_raw/theora/parameter_updates
/prius/front_camera/parameter_descriptions
/prius/front_camera/parameter_updates
/prius/front_left_laser/scan
/prius/front_right_laser/scan
/prius/front_sonar/left_far_range
/prius/front_sonar/left_middle_range
/prius/front_sonar/right_far_range
/prius/front_sonar/right_middle_range
/prius/left_camera/camera_info
/prius/left_camera/image_raw
/prius/left_camera/image_raw/compressed
/prius/left_camera/image_raw/compressed/parameter_descriptions
/prius/left_camera/image_raw/compressed/parameter_updates
/prius/left_camera/image_raw/compressedDepth
/prius/left_camera/image_raw/compressedDepth/parameter_descriptions
/prius/left_camera/image_raw/compressedDepth/parameter_updates
/prius/left_camera/image_raw/theora
/prius/left_camera/image_raw/theora/parameter_descriptions
/prius/left_camera/image_raw/theora/parameter_updates
/prius/left_camera/parameter_descriptions
/prius/left_camera/parameter_updates
/prius/right_camera/camera_info
/prius/right_camera/image_raw
/prius/right_camera/image_raw/compressed
/prius/right_camera/image_raw/compressed/parameter_descriptions
/prius/right_camera/image_raw/compressed/parameter_updates
/prius/right_camera/image_raw/compressedDepth
/prius/right_camera/image_raw/compressedDepth/parameter_descriptions
/prius/right_camera/image_raw/compressedDepth/parameter_updates
/prius/right_camera/image_raw/theora
/prius/right_camera/image_raw/theora/parameter_descriptions
/prius/right_camera/image_raw/theora/parameter_updates
/prius/right_camera/parameter_descriptions
/prius/right_camera/parameter_updates

其中，/prius # 控制车的topic，包括刹车、油门、档位、方向盘转向等命令

• 简单的控制（随便给的控制命令）

import rospy
from prius_msgs.msg import Control

def control_test():
    pub = rospy.Publisher("/prius", Control, queue_size=1)
    rospy.init_node('sim_control', anonymous=True)
    rate = rospy.Rate(10) # 10hz
    command = Control()
    command.header.stamp = rospy.Time.now()
    command.throttle = 1.0
    command.brake = 0.0
    command.shift_gears = Control.FORWARD
    
    while not rospy.is_shutdown():
        pub.publish(command)
        rate.sleep()

if __name__ == '__main__':
    try:
        control_test()
    except rospy.ROSInterruptException:
        pass 

我们看到车动机了。

总结

这个无人车仿真环境非常适合，有ROS基础的，并且想基于ROS进行一些研究的童鞋。其它的仿真环境真的很大，非常考验电脑的性能。