simple fake odometry publisher

asked 2019-10-12 04:31:24 -0500

june2473 gravatar image

updated 2019-10-12 23:37:08 -0500

I want to test rtabmap. I have d435 camera, but I dont have wheels yet.

So, I want to use simple fake odometry publisher, to publish zeros, to pretend that robot is not moving.

I tried this code, but I am not sure that it is working correctly, because I have got freezes of mapCloud. And I am afraid it is somehow related to this code.

#!/usr/bin/env python

import math
from math import sin, cos, pi

import rospy
import tf
from nav_msgs.msg import Odometry
from geometry_msgs.msg import Point, Pose, Quaternion, Twist, Vector3

rospy.init_node('odometry_publisher')

odom_pub = rospy.Publisher("odom", Odometry, queue_size=50)
odom_broadcaster = tf.TransformBroadcaster()

x = 0.0
y = 0.0
th = 0.0

vx = 0.0
vy = 0.0
vth = 0.0

current_time = rospy.Time.now()
last_time = rospy.Time.now()

r = rospy.Rate(50.0)
while not rospy.is_shutdown():
  current_time = rospy.Time.now()

  # compute odometry in a typical way given the velocities of the robot
  dt = (current_time - last_time).to_sec()
  delta_x = (vx * cos(th) - vy * sin(th)) * dt
  delta_y = (vx * sin(th) + vy * cos(th)) * dt
  delta_th = vth * dt

  x += delta_x
  y += delta_y
  th += delta_th

  # since all odometry is 6DOF we'll need a quaternion created from yaw
  odom_quat = tf.transformations.quaternion_from_euler(0, 0, th)

  # first, we'll publish the transform over tf
  odom_broadcaster.sendTransform( (x, y, 0.), odom_quat, current_time, "base_link",  "odom" )

  # next, we'll publish the odometry message over ROS
  odom = Odometry()
  odom.header.stamp = current_time
  odom.header.frame_id = "odom"

  # set the position
  odom.pose.pose = Pose(Point(x, y, 0.), Quaternion(*odom_quat))

  # set the velocity
  odom.child_frame_id = "base_link"
  odom.twist.twist = Twist(Vector3(vx, vy, 0), Vector3(0, 0, vth))

  # publish the message
  odom_pub.publish(odom)

  last_time = current_time
  r.sleep()

Is this code correct to publish zeros in odometry?

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