adding odometry

src/turtlebot_controller/CMakeLists.txt

@@ -6,6 +6,10 @@ find_package(catkin REQUIRED COMPONENTS
   rospy
   std_msgs
   geometry_msgs
+  sensor_msgs
+  nav_msgs
+  tf2
+  tf2_ros
 )
 find_package(Eigen3 REQUIRED)
 
@@ -14,6 +18,10 @@ INCLUDE_DIRS include
 CATKIN_DEPENDS 
 std_msgs
 geometry_msgs
+sensor_msgs
+nav_msgs
+tf2
+tf2_ros
 DEPENDS Eigen3
 #  DEPENDS system_lib
 )

src/turtlebot_controller/include/turtlebot_controller/simple_controller.h

@@ -1,18 +1,44 @@
 #ifndef SIMPLE_CONTROLLER_H
 #define SIMPLE_CONTROLLER_H
+
 #include <ros/ros.h>
 #include <geometry_msgs/Twist.h>
 #include <Eigen/Core>
+#include <sensor_msgs/JointState.h>
+#include <nav_msgs/Odometry.h>
+#include <geometry_msgs/TransformStamped.h>
+
+
 class SimpleController
 {
 public:
-    SimpleController(const ros::NodeHandle & ,double radius, double seperation);
+    SimpleController(const ros::NodeHandle &, double radius, double separation);
+
 private:
-    void velCallBack(const geometry_msgs::Twist &);
+    void velCallback(const geometry_msgs::Twist &);
+
+    void jointCallback(const sensor_msgs::JointState &);
+
     ros::NodeHandle nh_;
     ros::Subscriber vel_sub_;
     ros::Publisher right_cmd_pub_;
     ros::Publisher left_cmd_pub_;
+    ros::Subscriber joint_sub_;
+    ros::Publisher odom_pub_;
+
+    // Differential Kinematics
     Eigen::Matrix2d speed_conversion_;
+
+    // Odometry
+    double wheel_radius_;
+    double wheel_separation_;
+    double right_wheel_prev_pos_;
+    double left_wheel_prev_pos_;
+    ros::Time prev_time_;
+    nav_msgs::Odometry odom_msg_;
+    double x_;
+    double y_;
+    double theta_;
+    geometry_msgs::TransformStamped transform_stamped_;
 };
 #endif 

src/turtlebot_controller/nodes/simple_controller_node.cpp

@@ -1,15 +1,17 @@
 #include <ros/ros.h>
 #include "turtlebot_controller/simple_controller.h"
 
-int main(int argc, char **argv){
+
+int main(int argc, char **argv)
+{
     ros::init(argc, argv, "simple_controller");
     ros::NodeHandle nh;
     ros::NodeHandle pnh("~");
-    double wheel_radius;
+    double wheel_radius, wheel_separation;
     pnh.getParam("wheel_radius", wheel_radius);
-    double wheel_seperation;
+    pnh.getParam("wheel_separation", wheel_separation);
-    pnh.getParam("wheel_seperation", wheel_seperation);
+    SimpleController controller(nh, wheel_radius, wheel_separation);
-    SimpleController controller(nh, wheel_radius, wheel_seperation);
     ros::spin();
+
     return 0;
 }

src/turtlebot_controller/package.xml

@@ -54,14 +54,26 @@
   <build_depend>std_msgs</build_depend>
   <build_depend>geometry_msgs</build_depend>
   <build_depend>eigen</build_depend>
+  <build_depend>sensor_msgs</build_depend>
+  <build_depend>nav_msgs</build_depend>
+  <build_depend>tf2</build_depend>
+  <build_depend>tf2_ros</build_depend>
   <build_export_depend>roscpp</build_export_depend>
   <build_export_depend>rospy</build_export_depend>
   <build_export_depend>eigen</build_export_depend>
+  <build_export_depend>sensor_msgs</build_export_depend>
+  <build_export_depend>nav_msgs</build_export_depend>
+  <build_export_depend>tf2</build_export_depend>
+  <build_export_depend>tf2_ros</build_export_depend>
   <exec_depend>roscpp</exec_depend>
   <exec_depend>rospy</exec_depend>
   <exec_depend>std_msgs</exec_depend>
   <exec_depend>geometry_msgs</exec_depend>
   <exec_depend>eigen</exec_depend>
+  <exec_depend>sensor_msgs</exec_depend>
+  <exec_depend>nav_msgs</exec_depend>
+  <exec_depend>tf2</exec_depend>
+  <exec_depend>tf2_ros</exec_depend>
 
   <!-- The export tag contains other, unspecified, tags -->
   <export>

src/turtlebot_controller/src/simple_controller.cpp

@@ -1,29 +1,116 @@
-#include <turtlebot_controller/simple_controller.h>
+#include "turtlebot_controller/simple_controller.h"
 #include <std_msgs/Float64.h>
 #include <Eigen/Geometry>
+#include <tf2/LinearMath/Quaternion.h>
+#include <tf2_ros/transform_broadcaster.h>
 
-SimpleController::SimpleController(const ros::NodeHandle &nh ,double radius, double seperation): nh_(nh)
+
+SimpleController::SimpleController(const ros::NodeHandle &nh,
+                                   double radius,
+                                   double separation)
+                                  : nh_(nh)
+                                  , wheel_radius_(radius)
+                                  , wheel_separation_(separation)
+                                  , left_wheel_prev_pos_(0.0)
+                                  , right_wheel_prev_pos_(0.0)
+                                  , x_(0.0)
+                                  , y_(0.0)
+                                  , theta_(0.0)
 {
-    ROS_INFO_STREAM("Using wheel raduis" << radius);
+    ROS_INFO_STREAM("Using wheel radius " << radius);
-    ROS_INFO_STREAM("Using wheel seperation" << seperation);
+    ROS_INFO_STREAM("Using wheel separation " << separation);
     right_cmd_pub_ = nh_.advertise<std_msgs::Float64>("wheel_right_controller/command", 10);
     left_cmd_pub_ = nh_.advertise<std_msgs::Float64>("wheel_left_controller/command", 10);
+    vel_sub_ = nh_.subscribe("kubot_description/cmd_vel", 1000, &SimpleController::velCallback, this);
+    joint_sub_ = nh_.subscribe("joint_states", 1000, &SimpleController::jointCallback, this);
+    odom_pub_ = nh_.advertise<nav_msgs::Odometry>("kubot_description/odom", 10);
 
-    vel_sub_ = nh_.subscribe("turtlebot_controller/cmd.vel", 1000, &SimpleController::velCallBack, this);
+    speed_conversion_ << radius/2, radius/2, radius/separation, -radius/separation;
-    speed_conversion_ <<radius/2, radius/2, radius/seperation, -radius/seperation;
     ROS_INFO_STREAM("The conversion matrix is \n" << speed_conversion_);
+
+    // Fill the Odometry message with invariant parameters
+    odom_msg_.header.frame_id = "odom";
+    odom_msg_.child_frame_id = "base_footprint";
+    odom_msg_.pose.pose.orientation.x = 0.0;
+    odom_msg_.pose.pose.orientation.y = 0.0;
+    odom_msg_.pose.pose.orientation.z = 0.0;
+    odom_msg_.pose.pose.orientation.w = 1.0;
+
+    transform_stamped_.header.frame_id = "odom";
+    transform_stamped_.child_frame_id = "base_footprint";
+
+    prev_time_ = ros::Time::now();
 }
-void SimpleController::velCallBack(const geometry_msgs::Twist &msg)
+
+
+void SimpleController::velCallback(const geometry_msgs::Twist &msg)
 {
+    // Implements the differential kinematic model
+    // Given v and w, calculate the velocities of the wheels
     Eigen::Vector2d robot_speed(msg.linear.x, msg.angular.z);
     Eigen::Vector2d wheel_speed = speed_conversion_.inverse() * robot_speed;
-
     std_msgs::Float64 right_speed;
-    std_msgs::Float64 left_speed;
     right_speed.data = wheel_speed.coeff(0);
+    std_msgs::Float64 left_speed;
     left_speed.data = wheel_speed.coeff(1);
 
     right_cmd_pub_.publish(right_speed);
     left_cmd_pub_.publish(left_speed);
-
+}
+
+
+void SimpleController::jointCallback(const sensor_msgs::JointState &state)
+{
+    // Implements the inverse differential kinematic model
+    // Given the position of the wheels, calculates their velocities
+    // then calculates the velocity of the robot wrt the robot frame
+    // and then converts it in the global frame and publishes the TF
+    double dp_left = state.position.at(0) - left_wheel_prev_pos_;
+    double dp_right = state.position.at(1) - right_wheel_prev_pos_;
+    double dt = (state.header.stamp - prev_time_).toSec();
+
+    // Actualize the prev pose for the next itheration
+    left_wheel_prev_pos_ = state.position.at(0);
+    right_wheel_prev_pos_ = state.position.at(1);
+    prev_time_ = state.header.stamp;
+
+    // Calculate the rotational speed of each wheel
+    double fi_left = dp_left / dt;
+    double fi_right = dp_right / dt;
+
+    // Calculate the linear and angular velocity
+    double linear = (wheel_radius_ * fi_right + wheel_radius_ * fi_left) / 2;
+    double angular = (wheel_radius_ * fi_right - wheel_radius_ * fi_left) / wheel_separation_;
+
+    // Calculate the position increment
+    double d_s = (wheel_radius_ * dp_right + wheel_radius_ * dp_left) / 2;
+    double d_theta = (wheel_radius_ * dp_right - wheel_radius_ * dp_left) / wheel_separation_;
+    theta_ += d_theta;
+    x_ += d_s * cos(theta_);
+    y_ += d_s * sin(theta_);
+
+    // Compose and publish the odom message
+    tf2::Quaternion q;
+    q.setRPY(0, 0, theta_);
+    odom_msg_.header.stamp = ros::Time::now();
+    odom_msg_.pose.pose.position.x = x_;
+    odom_msg_.pose.pose.position.y = y_;
+    odom_msg_.pose.pose.orientation.x = q.getX();
+    odom_msg_.pose.pose.orientation.y = q.getY();
+    odom_msg_.pose.pose.orientation.z = q.getZ();
+    odom_msg_.pose.pose.orientation.w = q.getW();
+    odom_msg_.twist.twist.linear.x = linear;
+    odom_msg_.twist.twist.angular.z = angular;
+    odom_pub_.publish(odom_msg_);
+
+    // TF
+    static tf2_ros::TransformBroadcaster br;
+    transform_stamped_.transform.translation.x = x_;
+    transform_stamped_.transform.translation.y = y_;
+    transform_stamped_.transform.rotation.x = q.getX();
+    transform_stamped_.transform.rotation.y = q.getY();
+    transform_stamped_.transform.rotation.z = q.getZ();
+    transform_stamped_.transform.rotation.w = q.getW();
+    transform_stamped_.header.stamp = ros::Time::now();
+    br.sendTransform(transform_stamped_);
 }