turtlesim画正方形代码对比

Posted 2022-03-09 zhangrelay

ROS1/2主题/服务/行动基础类turtlesim阶段测试公开题

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画正方形或者其他形状有两类实现方式：

1 ☞ 

#include <boost/bind.hpp>
#include <ros/ros.h>
#include <turtlesim/Pose.h>
#include <geometry_msgs/Twist.h>
#include <std_srvs/Empty.h>

turtlesim::PoseConstPtr g_pose;
turtlesim::Pose g_goal;

enum State

  FORWARD,
  STOP_FORWARD,
  TURN,
  STOP_TURN,
;

State g_state = FORWARD;
State g_last_state = FORWARD;
bool g_first_goal_set = false;

#define PI 3.141592

void poseCallback(const turtlesim::PoseConstPtr& pose)

  g_pose = pose;


bool hasReachedGoal()

  return fabsf(g_pose->x - g_goal.x) < 0.1 && fabsf(g_pose->y - g_goal.y) < 0.1 && fabsf(g_pose->theta - g_goal.theta) < 0.01;


bool hasStopped()

  return g_pose->angular_velocity < 0.0001 && g_pose->linear_velocity < 0.0001;


void printGoal()

  ROS_INFO("New goal [%f %f, %f]", g_goal.x, g_goal.y, g_goal.theta);


void commandTurtle(ros::Publisher twist_pub, float linear, float angular)

  geometry_msgs::Twist twist;
  twist.linear.x = linear;
  twist.angular.z = angular;
  twist_pub.publish(twist);


void stopForward(ros::Publisher twist_pub)

  if (hasStopped())
  
    ROS_INFO("Reached goal");
    g_state = TURN;
    g_goal.x = g_pose->x;
    g_goal.y = g_pose->y;
    g_goal.theta = fmod(g_pose->theta + PI/2.0, 2*PI);
    // wrap g_goal.theta to [-pi, pi)
    if (g_goal.theta >= PI) g_goal.theta -= 2 * PI;
    printGoal();
  
  else
  
    commandTurtle(twist_pub, 0, 0);
  


void stopTurn(ros::Publisher twist_pub)

  if (hasStopped())
  
    ROS_INFO("Reached goal");
    g_state = FORWARD;
    g_goal.x = cos(g_pose->theta) * 2 + g_pose->x;
    g_goal.y = sin(g_pose->theta) * 2 + g_pose->y;
    g_goal.theta = g_pose->theta;
    printGoal();
  
  else
  
    commandTurtle(twist_pub, 0, 0);
  



void forward(ros::Publisher twist_pub)

  if (hasReachedGoal())
  
    g_state = STOP_FORWARD;
    commandTurtle(twist_pub, 0, 0);
  
  else
  
    commandTurtle(twist_pub, 1.0, 0.0);
  


void turn(ros::Publisher twist_pub)

  if (hasReachedGoal())
  
    g_state = STOP_TURN;
    commandTurtle(twist_pub, 0, 0);
  
  else
  
    commandTurtle(twist_pub, 0.0, 0.4);
  


void timerCallback(const ros::TimerEvent&, ros::Publisher twist_pub)

  if (!g_pose)
  
    return;
  

  if (!g_first_goal_set)
  
    g_first_goal_set = true;
    g_state = FORWARD;
    g_goal.x = cos(g_pose->theta) * 2 + g_pose->x;
    g_goal.y = sin(g_pose->theta) * 2 + g_pose->y;
    g_goal.theta = g_pose->theta;
    printGoal();
  

  if (g_state == FORWARD)
  
    forward(twist_pub);
  
  else if (g_state == STOP_FORWARD)
  
    stopForward(twist_pub);
  
  else if (g_state == TURN)
  
    turn(twist_pub);
  
  else if (g_state == STOP_TURN)
  
    stopTurn(twist_pub);
  


int main(int argc, char** argv)

  ros::init(argc, argv, "draw_square");
  ros::NodeHandle nh;
  ros::Subscriber pose_sub = nh.subscribe("turtle1/pose", 1, poseCallback);
  ros::Publisher twist_pub = nh.advertise<geometry_msgs::Twist>("turtle1/cmd_vel", 1);
  ros::ServiceClient reset = nh.serviceClient<std_srvs::Empty>("reset");
  ros::Timer timer = nh.createTimer(ros::Duration(0.016), boost::bind(timerCallback, _1, twist_pub));

  std_srvs::Empty empty;
  reset.call(empty);

  ros::spin();

 

2 ☞

#include <ros/ros.h>
#include <turtlesim/Pose.h>
#include <actionlib/server/simple_action_server.h>
#include <cmath>
#include <math.h>
#include <angles/angles.h>

#include <geometry_msgs/Twist.h>
#include <turtle_actionlib/ShapeAction.h>

// This class computes the command_velocities of the turtle to draw regular polygons 
class ShapeAction

public:
  ShapeAction(std::string name) : 
    as_(nh_, name, false),
    action_name_(name)
  
    //register the goal and feeback callbacks
    as_.registerGoalCallback(boost::bind(&ShapeAction::goalCB, this));
    as_.registerPreemptCallback(boost::bind(&ShapeAction::preemptCB, this));

    //subscribe to the data topic of interest
    sub_ = nh_.subscribe("/turtle1/pose", 1, &ShapeAction::controlCB, this);
    pub_ = nh_.advertise<geometry_msgs::Twist>("/turtle1/cmd_vel", 1);

    as_.start();
  

  ~ShapeAction(void)
  
  

  void goalCB()
  
    // accept the new goal
    turtle_actionlib::ShapeGoal goal = *as_.acceptNewGoal();
    //save the goal as private variables
    edges_ = goal.edges;
    radius_ = goal.radius;

    // reset helper variables
    interior_angle_ = ((edges_-2)*M_PI)/edges_;
    apothem_ = radius_*cos(M_PI/edges_);
    //compute the side length of the polygon
    side_len_ = apothem_ * 2* tan( M_PI/edges_);
    //store the result values
    result_.apothem = apothem_;
    result_.interior_angle = interior_angle_;
    edge_progress_ =0;
    start_edge_ = true;
  

  void preemptCB()
  
    ROS_INFO("%s: Preempted", action_name_.c_str());
    // set the action state to preempted
    as_.setPreempted();
  

  void controlCB(const turtlesim::Pose::ConstPtr& msg)
  
    // make sure that the action hasn't been canceled
    if (!as_.isActive())
      return;
  
    if (edge_progress_ < edges_)
    
      // scalar values for drive the turtle faster and straighter
      double l_scale = 6.0;
      double a_scale = 6.0;
      double error_tol = 0.00001;

      if (start_edge_)
      
        start_x_ = msg->x;
        start_y_ = msg->y;
        start_theta_ = msg->theta;
        start_edge_ = false;
      

      // compute the distance and theta error for the shape
      dis_error_ = side_len_ - fabs(sqrt((start_x_- msg->x)*(start_x_-msg->x) + (start_y_-msg->y)*(start_y_-msg->y)));
      theta_error_ = angles::normalize_angle_positive(M_PI - interior_angle_ - (msg->theta - start_theta_));
     
      if (dis_error_ > error_tol)
      
        command_.linear.x = l_scale*dis_error_;
        command_.angular.z = 0;
      
      else if (dis_error_ < error_tol && fabs(theta_error_)> error_tol)
       
        command_.linear.x = 0;
        command_.angular.z = a_scale*theta_error_;
      
      else if (dis_error_ < error_tol && fabs(theta_error_)< error_tol)
      
        command_.linear.x = 0;
        command_.angular.z = 0;
        start_edge_ = true;
        edge_progress_++;
        
      else
      
        command_.linear.x = l_scale*dis_error_;
        command_.angular.z = a_scale*theta_error_;
       
      // publish the velocity command
      pub_.publish(command_);
      
     
    else
              
      ROS_INFO("%s: Succeeded", action_name_.c_str());
      // set the action state to succeeded
      as_.setSucceeded(result_);
       
  

protected:
  ros::NodeHandle nh_;
  actionlib::SimpleActionServer<turtle_actionlib::ShapeAction> as_;
  std::string action_name_;
  double radius_, apothem_, interior_angle_, side_len_;
  double start_x_, start_y_, start_theta_;
  double dis_error_, theta_error_;
  int edges_ , edge_progress_;
  bool start_edge_;
  geometry_msgs::Twist command_;
  turtle_actionlib::ShapeResult result_;
  ros::Subscriber sub_;
  ros::Publisher pub_;
;

int main(int argc, char** argv)

  ros::init(argc, argv, "turtle_shape");

  ShapeAction shape(ros::this_node::getName());
  ros::spin();

  return 0;

#include <ros/ros.h>
#include <actionlib/client/simple_action_client.h>
#include <actionlib/client/terminal_state.h>
#include <turtle_actionlib/ShapeAction.h>

int main (int argc, char **argv)

  ros::init(argc, argv, "test_shape"); 

  // create the action client
  // true causes the client to spin it's own thread
  actionlib::SimpleActionClient<turtle_actionlib::ShapeAction> ac("turtle_shape", true); 

  ROS_INFO("Waiting for action server to start.");
  // wait for the action server to start
  ac.waitForServer(); //will wait for infinite time
 
  ROS_INFO("Action server started, sending goal.");
  // send a goal to the action 
  turtle_actionlib::ShapeGoal goal;
  goal.edges = 4;
  goal.radius = 1.3;
  ac.sendGoal(goal);
  
  //wait for the action to return
  bool finished_before_timeout = ac.waitForResult(ros::Duration(40.0));

  if (finished_before_timeout)
    
      actionlib::SimpleClientGoalState state = ac.getState();
      ROS_INFO("Action finished: %s",state.toString().c_str());
    
  else  
    ROS_INFO("Action did not finish before the time out.");

  //exit
  return 0;

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对比发现第2种，精度高一些，为何？

如何提升第1种方式绘制图形的精度。

如何绘制任意图形？

turtlesim之欢度国庆（ROS2二维轨迹之随心所欲）

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