content

Implement parameter server new (modified) parameters

Implementing parameter server queries

Parameter server delete implementation

Python implementation

Implement server new modification parameters

Implement server query parameters

Parameter server deletion implementation

Introduction

The parameter server is mainly used to realize data sharing between different nodes in ROS. The parameter server is equivalent to a common container independent of all nodes. Data can be stored in the container and called by different nodes. Of course, different nodes can also store data in it. The typical application scenarios of the parameter server are as follows:

When the navigation is implemented, path planning will be carried out, such as: global path planning, design a rough path from the starting point to the target point. Local path planning, which will generate the travel path from time to time according to the current road conditions

In the above scenario, the parameter server is used for global path planning and local path planning:

When planning the path, we need to refer to the size of the car. We can store these size information in the parameter server. Both the global path planning node and the local path planning node can call these parameters from the parameter server.

The parameter server is generally suitable for some application scenarios where data sharing exists.

theoretical model

It is not efficient because it uses the rpc protocol

iso8601 dates are date data

C++ implementation

New feature pack

Then press enter to depend on roscpp rospy std_msgs

Implement parameter server new (modified) parameters

then create a new file

Write the following code

Modify CMakeLists

then compile

Then start the terminal and execute

You can see that the parameters are passed in

Parameter information can also be found

Next, modify the parameters

You can see that the keys are the same

So the later overwriting the previous key value actually implements the modification

test

was changed to 0.2

Implementing parameter server queries

create a new file

Then modify the CMakeLists

Then enter the following code to test the query function

compile

then test

test getparam

open terminal

test getparamnames

open terminal

successful traversal

test ros::param

terminal

Parameter server delete implementation

create a new file

Change setting

Copy the code below

/* 
    参数服务器操作之删除_C++实现:

    ros::NodeHandle
        deleteParam("键")
        根据键删除参数，删除成功，返回 true，否则(参数不存在)，返回 false

    ros::param
        del("键")
        根据键删除参数，删除成功，返回 true，否则(参数不存在)，返回 false


*/
#include "ros/ros.h"


int main(int argc, char *argv[])
{   
    setlocale(LC_ALL,"");
    ros::init(argc,argv,"delete_param");

    ros::NodeHandle nh;
    bool r1 = nh.deleteParam("nh_int");
    ROS_INFO("nh 删除结果:%d",r1);

    bool r2 = ros::param::del("param_int");
    ROS_INFO("param 删除结果:%d",r2);

    return 0;
}

Then

ctrl shift b compile

successfully deleted

Python implementation

new folder new file

Implement server new modification parameters

Copy the code below

#! /usr/bin/env python
"""
    参数服务器操作之新增与修改(二者API一样)_Python实现:
"""

import rospy

if __name__ == "__main__":
    rospy.init_node("set_update_paramter_p")

    # 设置各种类型参数
    rospy.set_param("p_int",10)
    rospy.set_param("p_double",3.14)
    rospy.set_param("p_bool",True)
    rospy.set_param("p_string","hello python")
    rospy.set_param("p_list",["hello","haha","xixi"])
    rospy.set_param("p_dict",{"name":"hulu","age":8})

    # 修改
    rospy.set_param("p_int",100)

Change setting

Then add execute permission

then compile

then start the command line

You can see that the operation was successful

Implement server query parameters

create a new file

Add executable permission

Configure CMakeLists

then compile

Then open terminal to test

test was successful

Parameter server deletion implementation

create a new file

Copy the code below

#! /usr/bin/env python
"""
    参数服务器操作之删除_Python实现:
    rospy.delete_param("键")
    键存在时，可以删除成功，键不存在时，会抛出异常
"""
import rospy

if __name__ == "__main__":
    rospy.init_node("delete_param_p")

    try:
        rospy.delete_param("p_int")
    except Exception as e:
        rospy.loginfo("删除失败")