Joint_velocity and tf scale is different

Hey,

i am trying to calculate odometry using wheel velocity published using the joint_state topic and compare the calculated position and rotation with the tf topic.

the problem i am having is that the calculated odometer quite large in scale when comparing to tf from isaac sim.

code I’m using for calculating odometry from wheel velocity.

    dt = (current_time - last_time).to_sec()

    vx = round(message.velocity[0], 1)
    vy = round(message.velocity[1], 1)

    v_rx = (vx + vy) / 2.0
    v_ry = 0
    omega_r = ( vx - vy ) / 4.5 # TODO proper distance between tires

    # compute odometry in a typical way given the velocities of the robot
    delta_x = (v_rx * cos(th) - v_ry * sin(th)) * dt
    delta_y = (v_rx * sin(th) + v_ry * cos(th)) * dt
    delta_th = omega_r * dt

    # updating x, y and theta
    x += delta_x
    y += delta_y
    th += delta_th

    quaternion = Quaternion()
    quaternion.x = 0.0 
    quaternion.y = 0.0
    quaternion.z = sin(th / 2.0)
    quaternion.w = cos(th / 2.0)

    # Create the odometry transform frame broadcaster.
    odomBroadcaster.sendTransform(
        (x, y, 0), 
        (quaternion.x, quaternion.y, quaternion.z, quaternion.w),
        rospy.Time.now(),
        "base_footprint",
        "world"
        )

    odom = Odometry()
    odom.header.frame_id = "world"
    odom.child_frame_id = "base_footprint"
    odom.header.stamp = current_time
    odom.pose.pose.position.x = x
    odom.pose.pose.position.y = y
    odom.pose.pose.position.z = 0
    odom.pose.pose.orientation = quaternion
    odom.twist.twist.linear.x = vx
    odom.twist.twist.linear.y = vy
    odom.twist.twist.angular.z = vth
    odomPub.publish(odom)

image

really appreciate any help.
Regards

@wakasu can you test this with isaac sim 2021.1.0 and see if the issue persists?

We also have a new rosnav sample that might be useful: ROS Navigation — Omniverse Robotics documentation