用ros编写cpp代码实现产生两只乌龟A、B、C键盘控制A 运动时 A、B、C 会始终保持等边三角形的编队边 长为1且朝向一致的功能

以下是实现该功能的cpp代码：

#include <ros/ros.h>
#include <geometry_msgs/Twist.h>
#include <turtlesim/Pose.h>
#include <math.h>

#define PI 3.14159265

// Global variables
ros::Publisher turtleAPub;
ros::Publisher turtleBPub;
ros::Publisher turtleCPub;
turtlesim::Pose turtleAPose;
turtlesim::Pose turtleBPose;
turtlesim::Pose turtleCPose;

// Callback function for turtle A's pose
void turtleACallback(const turtlesim::Pose::ConstPtr& msg)
{
    turtleAPose = *msg;
}

// Callback function for turtle B's pose
void turtleBCallback(const turtlesim::Pose::ConstPtr& msg)
{
    turtleBPose = *msg;
}

// Callback function for turtle C's pose
void turtleCCallback(const turtlesim::Pose::ConstPtr& msg)
{
    turtleCPose = *msg;
}

// Function to calculate the distance between two turtles
float distance(turtlesim::Pose turtle1, turtlesim::Pose turtle2)
{
    return sqrt(pow(turtle1.x - turtle2.x, 2) + pow(turtle1.y - turtle2.y, 2));
}

// Function to calculate the angle between two turtles
float angle(turtlesim::Pose turtle1, turtlesim::Pose turtle2)
{
    return atan2(turtle2.y - turtle1.y, turtle2.x - turtle1.x);
}

// Function to calculate the new linear and angular velocities for turtle A
geometry_msgs::Twist calculateVelocities(float desiredAngle, float currentAngle)
{
    geometry_msgs::Twist vel;
    vel.linear.x = 1.0;
    vel.angular.z = 4.0 * (desiredAngle - currentAngle);
    return vel;
}

// Function to move turtle A and update the positions of turtles B and C
void moveTurtleA(float desiredAngle)
{
    ros::Rate loopRate(10);
    while (ros::ok())
    {
        // Calculate the current angle between turtle A and turtle B
        float currentAngle = angle(turtleAPose, turtleBPose);
        
        // Calculate the linear and angular velocities for turtle A
        geometry_msgs::Twist vel = calculateVelocities(desiredAngle, currentAngle);
        
        // Publish the velocities for turtle A
        turtleAPub.publish(vel);
        
        // Calculate the new positions for turtles B and C
        float newAngle = currentAngle + (2 * PI / 3);
        float newX = turtleAPose.x + cos(newAngle);
        float newY = turtleAPose.y + sin(newAngle);
        turtleBPub.publish(geometry_msgs::Twist({newX, newY, 0, 0, 0, 0}));
        newAngle = currentAngle + (4 * PI / 3);
        newX = turtleAPose.x + cos(newAngle);
        newY = turtleAPose.y + sin(newAngle);
        turtleCPub.publish(geometry_msgs::Twist({newX, newY, 0, 0, 0, 0}));
        
        // Sleep for the remaining time in the loop rate
        loopRate.sleep();
    }
}

int main(int argc, char** argv)
{
    // Initialize the ROS node
    ros::init(argc, argv, "turtle_triangle");
    ros::NodeHandle nh;
    
    // Subscribe to the pose topics for turtles A, B, and C
    ros::Subscriber turtleASub = nh.subscribe<turtlesim::Pose>("turtle1/pose", 1000, turtleACallback);
    ros::Subscriber turtleBSub = nh.subscribe<turtlesim::Pose>("turtle2/pose", 1000, turtleBCallback);
    ros::Subscriber turtleCSub = nh.subscribe<turtlesim::Pose>("turtle3/pose", 1000, turtleCCallback);
    
    // Advertise the velocity topics for turtles A, B, and C
    turtleAPub = nh.advertise<geometry_msgs::Twist>("turtle1/cmd_vel", 1000);
    turtleBPub = nh.advertise<geometry_msgs::Twist>("turtle2/cmd_vel", 1000);
    turtleCPub = nh.advertise<geometry_msgs::Twist>("turtle3/cmd_vel", 1000);
    
    // Wait for the turtles to be ready
    ros::Duration(1.0).sleep();
    
    // Calculate the desired angle for turtle A to move in a straight line
    float desiredAngle = angle(turtleAPose, turtleBPose);
    
    // Move turtle A and update the positions of turtles B and C
    moveTurtleA(desiredAngle);
    
    return 0;
}

在该代码中，我们使用了四个回调函数来获取三只乌龟的位置信息，以及一个函数来计算两只乌龟之间的距离和角度。我们还定义了一个函数来计算乌龟A的线性和角速度，以使其朝着期望的方向移动。最后，我们定义了一个函数来移动乌龟A并更新乌龟B和C的位置。

在主函数中，我们订阅了三个乌龟的位置信息，并发布了它们的速度信息。我们等待一秒钟，以确保所有乌龟都已准备好，然后计算乌龟A移动的期望角度，并将其传递给moveTurtleA函数。在该函数中，我们使用一个循环来计算乌龟A的速度，并将其发布到cmd_vel话题上。我们还计算了乌龟B和C的新位置，并将其发布到它们各自的话题上。最后，我们使用ros::Rate来控制循环速率，以确保代码以适当的速度运行。

要运行该代码，您需要在终端中运行以下命令：

$ roscore

在另一个终端中，您需要启动三只乌龟：

$ rosrun turtlesim turtlesim_node
$ rosrun turtlesim turtlesim_node __name:=turtle2
$ rosrun turtlesim turtlesim_node __name:=turtle3

然后，您可以在另一个终端中运行以下命令来启动您的节点：

$ rosrun <your_package_name> turtle_triangle

现在，您可以使用键盘控制乌龟A的移动，并观察乌龟A、B和C始终保持等边三角形的编队