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2016-02-23 05:42:50 -0500 asked a question turtlebot 1 not working with keyboard_teleop.

I have just started working on Turtlebot1. I wanted to use keyboard_teleop for moving turtlebot. I am using iRobot create base for this purpose (Kinect is not added). After executing command roslaunch turtlebot_bringup minimal.launch, i get an error as-

[WARN] [WallTime: 1456226724.415139] Create : robot not connected yet, sci not available

and the turtlebot turns OFF. I turn ON turtlebot and execute command roslaunch turtlebot_teleop keyboard_teleop.launch. After this command, i get an error as-

[WARN] [WallTime: 1456227470.487644] Failed to read sensor package. 5 retries left. [WARN] [WallTime: 1456227485.445873] Could not load a calibration file for this turtlebot, it is recommended to run turtlebot_calibration to generate a new file. [WARN] [WallTime: 1456227485.446356] Search paths: FTF8TAG204036001.yaml , /home/rekha/.ros/turtlebot_create/FTF8TAG204036001.yaml , /opt/ros/indigo/share/create_node/FTF8TAG204036001.yaml

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2015-10-17 06:48:03 -0500 asked a question getting x, y, theta from wheel encoder values for P3DX robot

I am using getLeftEncoder() and getRightEnoder() functions from Aria library. i am publishing left and right encoder values using custom message. I calculated x, y and theta. The robot has to follow 2*2 square grid for 5 times. The plot i am getting is not desired and kind of random. can anybody tell me where am i getting wrong?

Below is the code i have used-

#include "ros/ros.h"
#include "std_msgs/Float64.h"
#include "rosaria/custom_encoder.h"
#include <iostream>
#include <fstream>
#include <math.h> 

using namespace std;

float b_actual = 0.3226;
float Cm = 0.0000078125;  /*(units = meters/pulse)*/
float Cl = 1.0000;
float Cr = 1.0000;

float thetaold = 0;
float xold = 0;
float yold = 0;
float _previousEnL = 0;
float _previousEnR = 0;
float dU, EnL, EnR, dUL, dUR, dtheta, x, y, theta, _currentEnL, _currentEnR;

void chatterCallback(const rosaria::custom_encoder::ConstPtr& msg)
  _currentEnL = msg->Left_Encoder;
  _currentEnR = msg->Right_Encoder;

  EnL = _currentEnL - _previousEnL;
  EnR = _currentEnR - _previousEnR;

  ROS_INFO("left encoder:[%f]:", EnL);
  ROS_INFO("right encoder:[%f]:", EnR);

  dUL = Cl * Cm * EnL;
  dUR = Cr * Cm * EnR;

  dU = (dUL + dUR)/2;
  dtheta = (dUL - dUR)/b_actual;

  theta = thetaold + dtheta;
  x = xold + dU * cos (theta);
  y = yold + dU * sin (theta);

  thetaold = theta;
  xold = x;
  yold = y;

  _previousEnL = _currentEnL; 
  _previousEnR = _currentEnR;

  ofstream People("mr.txt", std::ios_base::app);
  People <<x<< ", "<<y<< "," <<theta<<std::endl;
  ROS_INFO("Modified wheel Pose: (%f, %f, %f)", x, y, theta);


int main(int argc, char **argv)
  ros::init(argc, argv, "subs_pose");
  ros::NodeHandle n;
  ros::Subscriber sub = n.subscribe("/RosAria/custom_Encoder", 1000, chatterCallback);
  return 0;
2015-09-25 03:50:59 -0500 commented answer wheel encoders values is the ARIA library and it has command like "ArRobot::getLeftEncoder(void). But, i am not sure how to implement this command on p3dx. Any help or suggestion would be appreciated

2015-09-21 14:27:03 -0500 commented answer wheel encoders values

what does kinecalc do? why is it showing links in the code? is it for mobile robot only? Pls help

2015-09-21 14:24:36 -0500 commented question wheel encoders values

My goal is to find dead-reckoning error in wheel odometry. I found the systematic and non-systematic error. I just need raw wheel encoder values to recalculate the pose as per the errors found as above. Or i need the source code for finding pose in ROSARIA or P2OS

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2015-09-18 03:27:41 -0500 asked a question wheel encoders values

I am working on P3DX. i want to find wheel encoder values from p2os_driver library. In the p2os library, i m directly getting x, y and theta from buffer. Pls. Suggest.