Odometry does not transform in rviz
When I move my vehicle, odomety does not move in rviz, what is the reason , please help me..
#include "Motor.h"
#include <ros.h>
#include <ros/time.h>
#include <geometry_msgs/Twist.h>
#include <std_msgs/Int16.h>
#include<PID_v1.h>
ros::NodeHandle nh;
#define LOOPTIME 10
int updatenh;
Motor right(11,10,20,21);
Motor left(9,8,18,19);
volatile long encoder0Pos = 0; // encoder 1
volatile long encoder1Pos = 0; // encoder 2
double left_kp = 17 , left_ki = 0 , left_kd = 0.0; // modify for optimal performance
double right_kp = 20 , right_ki = 0 , right_kd = 0.0;
float demandx=0;
float demandz=0;
double demand_speed_left;
double demand_speed_right;
double right_input = 0, right_output = 0, right_setpoint = 0;
PID rightPID(&right_input, &right_output, &right_setpoint, right_kp, right_ki, right_kd, DIRECT);
double left_input = 0, left_output = 0, left_setpoint = 0;
PID leftPID(&left_input, &left_output, &left_setpoint, left_kp, left_ki, left_kd, DIRECT);
unsigned long currentMillis;
unsigned long prevMillis;
float encoder0Diff;
float encoder1Diff;
float encoder0Error;
float encoder1Error;
float encoder0Prev;
float encoder1Prev;
void cmd_vel_cb( const geometry_msgs::Twist& twist){
demandx = twist.linear.x;
demandz = twist.angular.z;
}
ros::Subscriber<geometry_msgs::Twist> sub("cmd_vel", cmd_vel_cb );
std_msgs::Int16 left_wheel_msg;
ros::Publisher left_wheel_pub("lwheel" , &left_wheel_msg);
std_msgs::Int16 right_wheel_msg;
ros::Publisher right_wheel_pub("rwheel" , &right_wheel_msg);
double pos_act_left = 0; //Actual speed for left wheel in m/s
double pos_act_right = 0; //Command speed for left wheel in m/s
void setup() {
nh.initNode();
nh.subscribe(sub);
nh.advertise(left_wheel_pub);
nh.advertise(right_wheel_pub); //prepare to publish speed in ROS topic
// Serial.begin(115200);
rightPID.SetMode(AUTOMATIC);
rightPID.SetSampleTime(1);
rightPID.SetOutputLimits(-100, 100);
leftPID.SetMode(AUTOMATIC);
leftPID.SetSampleTime(1);
leftPID.SetOutputLimits(-100, 100);
// Serial.println("Basic Encoder Test:");
attachInterrupt(digitalPinToInterrupt(left.en_a), change_left_a, CHANGE);
attachInterrupt(digitalPinToInterrupt(left.en_b), change_left_b, CHANGE);
attachInterrupt(digitalPinToInterrupt(right.en_a), change_right_a, CHANGE);
attachInterrupt(digitalPinToInterrupt(right.en_b), change_right_b, CHANGE);
}
void loop() {
currentMillis = millis();
if (currentMillis - prevMillis >= LOOPTIME){
prevMillis = currentMillis;
demand_speed_left = demandx - (demandz*0.1075);
demand_speed_right = demandx + (demandz*0.1075);
/*PID controller for speed control
Base speed being 1 ms and the demand_speed variables controlling it at fractions of the base.
The PID controller keeps trying to match the difference
in encoder counts to match with the required amount, hence controlling the speed. */
encoder0Diff = encoder0Pos - encoder0Prev; // Get difference between ticks to compute speed
encoder1Diff = encoder1Pos - encoder1Prev;
pos_act_left = encoder0Pos;
pos_act_right = encoder1Pos;
encoder0Error = (demand_speed_left*39.65)-encoder0Diff; // 3965 ticks in 1m = 39.65 ticks in 10ms, due to the 10 millis loop
encoder1Error = (demand_speed_right*39.65)-encoder1Diff;
encoder0Prev = encoder0Pos; // Saving values
encoder1Prev = encoder1Pos;
left_setpoint = demand_speed_left*39.65; //Setting required speed as a mul/frac of 1 m/s
right_setpoint = demand_speed_right*39.65;
left_input = encoder0Diff; //Input to PID controller is the current difference
right_input = encoder1Diff;
leftPID.Compute();
left.rotate(left_output);
rightPID.Compute();
right.rotate(right_output);
// Serial.print(encoder0Pos);
// Serial.print(",");
// Serial.println(encoder1Pos);
publishPos(LOOPTIME);
if(updatenh>10){
nh.spinOnce();
updatenh=0;
}else{
updatenh++;
}
}
}
//Publish function for odometry, uses a vector type message to send the data (message type is not meant for that but that's easier than creating a specific message type)
void publishPos(double time) {
int pos_act_left;
int pos_act_right;
left_wheel_msg.data = pos_act_left; //timestamp for odometry data
right_wheel_msg.data = pos_act_right; //left ...
Hi @ahmet, please provide more details of your exact problem like screenshots of the terminal window and tf tree so that we can help you better in solving your problem.
i added my code
car wheels are moving but tf tree not move
Ok, what do you mean by tf tree not move? a particular frame like
base_footprint
orodom
is not moving in rviz?yes,odom is not moving in rviz
Ok, it could be you are keeping wrong frame of reference in the global frame in rviz and that is why you cannot see the odom frame moving in rviz, but I think as @aarsh_t mentioned you need to publish the
nav_msgs/Odometry Message
and also launchrobot_state_publisher
node as this publishes all the tf information for visualizing in rviz and gazebo.I'm new to ros, can you help me make this edit? How should I add a code?
I agree with @Joe28965, it is better to watch vide tutorials about odometry so that you can understand the concept properly or ask your professor who can explain you better about it. To start, with you can have a look at this - http://wiki.ros.org/navigation/Tutori... You can also find many other tutorials here which can clear your concepts, also this - https://www.theconstructsim.com/ is a great place to learn ros through video tutorials, you can also find some of their videos on youtube. Hope this helps you. Good luck with your project !!