Welcome to ROSMASTER X3 Plus repository

3 Lidar guard

Lidar guard gameplay introduction:

• Set the lidar detection angle and response distance.
• After turning on the car, the car faces the target closest to the car.
• When the distance between the target and the car is less than the response distance, the buzzer keeps ringing until there is no target within the response distance.
• The PID of the angular velocity of the trolley can be adjusted to make the rotation of the trolley the best.

3.1 How to use

Note: The [R2] of the remote control handle has the function of [pause/open] for this gameplay. Due to the problem of the moving method, the case in this section does not support the Ackerman model. Different models, the parameter range will change, the principle is the same; take the X3 wheat wheel car as an example.

One key to start, after executing the command, the car starts to move.

#You need to enter docker first, perform this step more
#If running the script to enter docker fails, please refer to 07.Docker-orin/05, Enter the robot's docker container
~/run_docker.sh
roslaunch  yahboomcar_laser  laser_Warning.launch  

Dynamic debugging parameters

xxxxxxxxxx
rosrun  rqt_reconfigure  rqt_reconfigure 

Parameter parsing:

[ang_Kp], [ang_Ki], [ang_Kd]: PID debugging of car angular velocity.

In the box in front of [switch], click the value of [switch] to be True, and the car stops. [switch] The default is False, the car moves.

• parameter modification

When the parameters are adjusted to the optimal state, modify the corresponding parameters to the file, and there is no need to adjust them when using them again.

According to the optimal parameters of the [rqt_reconfigure] debugging tool, enter the [scripts] folder of the [yahboomcar_laser] function package, and modify the parameters corresponding to the [laser_Warning.py] file, as shown below

xxxxxxxxxx
class  laserWarning : 
     def __init__(self): 
        rospy.on_shutdown(self.cancel) 
 … 
        self.ang_pid = SinglePID(3.0, 0.0, 5.0) 
        Server(laserWarningPIDConfig, self.dynamic_reconfigure_callback) 
        self.laserAngle  =  70 
        self.ResponseDist  =  0.5 

[rqt_reconfigure] Modify the initial value of the debugging tool

xxxxxxxxxx
gen.add("ang_Kp", double_t, 0, "Kp in PID", 3.0, 0, 10) 
gen.add("ang_Ki", double_t, 0, "Ki in PID", 0.0, 0, 10) 
gen.add("ang_Kd", double_t, 0, "Kd in PID", 5.0, 0, 10) 
gen.add("laserAngle", int_t, 0, "laserAngle", 70, 10, 90) 
gen.add("ResponseDist", double_t, 0, "ResponseDist", 0.5, 0, 8) 
gen.add("switch", bool_t, 0, "switch in rosbot", False) 

Enter the [cfg] folder of the [yahboomcar_laser] function package, and modify the initial values of the parameters corresponding to the [laserWarningPID.cfg] file.

xxxxxxxxxx
gen.add("linear", double_t, 0, "linear in robot", 0.5, 0, 1.0) 

Analysis of the above one as an example

Note: After modification, the update environment must be recompiled to be effective.

xxxxxxxxxx
cd  ~/yahboomcar_ws 
catkin_make 
source  devel/setup.bash 

Node view

xxxxxxxxxx
rqt_graph 

3.2 source code analysis

launch file

• base.launch

xxxxxxxxxx
< launch > 
    <!-- start lidar node--> 
    <!-- Activate the lidar node --> 
    < include  file = "$(find rplidar_ros)/launch/rplidar.launch" /> 
    <!-- Start the car chassis drive node--> 
    <!-- Start the car chassis drive node --> 
    < include  file = "$(find yahboomcar_bringup)/launch/yahboomcar.launch" /> 
    <!-- handle control node --> 
    <!-- Handle control node --> 
    < include  file = "$(find yahboomcar_ctrl)/launch/yahboom_joy.launch" /> 
</ launch > 

• laser_Warning.launch

xxxxxxxxxx
< launch > 
    <!-- start the base.launch file--> 
    <!-- Launch the base.launch file --> 
    < include  file = "$(find yahboomcar_laser)/launch/base.launch" /> 
    <!-- start lidar guard node --> 
    <!-- Activate the Lidar guard node --> 
    < node  name = 'laser_Warning'  pkg = "yahboomcar_laser"  type = "laser_Warning.py"  required = "true"  output = "screen" /> 
</ launch > 

laser_Warning.py source code flow chart:

According to the position of the target, the trolley rotates autonomously to face the target; when the target is close to a certain distance, the buzzer alarms.