無人車系統（九）：基於ROS與Gazebo的無人駕駛仿真環境——car_demo

在car_demo|無人車仿真環境全教程介紹了在系統：Ubuntu 14.04 indigo中安裝配置car_demo。由於當時的電腦中的ubuntu與ros版本較低，我按照原教程的配置方法，安裝Docker，nvidia-docker2，還有rocker。最終實現的是，讓car_demo在獨立的docker環境下運行，利用ROS的多機通信的機制配置（如何配置請參見car_demo|無人車仿真環境全教程），使得在自己電腦上能夠與仿真環境進行數據交互。但是，這個過程真的好麻煩，使用感覺極爲不佳。最近正好換了電腦，索性直接把系統換到ubuntu 18.04+ ros melodic。發現直接在本地編譯能通過，之後就是本地的一個ros package，這樣使用就方便多了。

系統： ubuntu 18.04+ros melodic
目的：配置car_demo無人車仿真環境

安裝與配置過程

git clone car_demo項目到本地：

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

建立並定位到新工作空間，或已有工作空間~/cardemo_ws，這個位置與名字無所謂：

mkdir -p ~/cardemo_ws/src

將對應包複製到新建的工作空間的src目錄下：

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

編譯:

cd ~/cardemo_ws
catkin_make

添加環境

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

簡單測試

roslaunch car_demo demo.launch

我們會看到RVIZ與Gazebo兩個界面

RVIZ
Gazebo
查看topic數據(有激光、聲吶、相機、車自身狀態等數據)：

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   # 控制車的topic，包括剎車、油門、檔位、方向盤轉向等命令
/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 # 控制車的topic，包括剎車、油門、檔位、方向盤轉向等命令

簡單的控制（隨便給的控制命令）

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