bot stops working on changing tf listener 'target_frame' to '/odom', works fine for other frames

edit

I have written a simple P controller in the callback of my 'scan_subscriber' Subscriber. It is working as intended.

I also wanted to transform the laser scan data from '/base_laser' frame to '/odom' frame.

So, I wrote a simple transform listener inside 'tf_callback' function, setting the target_frame as '/odom'. This makes the bot to not work as intended (It moves for a while and then topples).

However, when I change the target_frame to any frame other than '/odom', the bot works just fine.

How can 'listener.waitForTransform' or 'listener.transformPoint' functions interfere with the publising of another topic ('/cmd_vel') ?

What am I missing? I have been trying to debug this for 2 days now.

#!/usr/bin/python

import rospy
from sensor_msgs.msg import LaserScan
import math
from geometry_msgs.msg import PointStamped,  Point, Twist
import tf
from visualization_msgs.msg import Marker 

class HuskyBot: 

    def __init__(self): 


        rospy.init_node('husky_node')

        self.laser_point = Point(0,0,0) 

        self.scan_subscriber = rospy.Subscriber('/scan', LaserScan, self.laser_callback)

        self.tf_subscriber = rospy.Subscriber('/scan' , LaserScan, self.tf_callback)

        self.velocity_publisher = rospy.Publisher('/cmd_vel' , Twist, queue_size = 1000) 

        self.rate = rospy.Rate(1)

        rospy.spin()


    def tf_callback(self, data): 




        laser_point_stamped  = PointStamped() 

        laser_point_stamped.header.frame_id = "/base_laser"
        laser_point_stamped.header.stamp = rospy.Time() 

        laser_point_stamped.point = self.laser_point 

        listener = tf.TransformListener()

        try: 

            last_time = rospy.Time.now() 


            ''' Program runs successfully on changing the target frame to any frame other than odom '''

            target_frame = '/odom'

            listener.waitForTransform(target_frame , '/base_laser' , rospy.Time(), rospy.Duration(1.0))


            odom_point = listener.transformPoint(target_frame , laser_point_stamped)


        except Exception as e: 

            print "Following exception was enconuntered while performing the transformation -> " + str(e)


    def laser_callback(self, data): 


        pillar_dis = 100000  

        pos = 0 


        for idx, val in enumerate(data.ranges) : 

            if not math.isinf(val): 

                if val  < pillar_dis : 

                    pillar_dis = val 

                    pos = idx 

        pillar_ang  = data.angle_min + pos * data.angle_increment 


        vel_msg = Twist() 

        tolerance = 0.1 

        ''' Simple P controller to navigate the bot ''' 

        if pillar_dis > tolerance : 

            v_x = 1.5 * pillar_dis 

            w_z = 4 * (0 - pillar_ang) 

            vel_msg.linear.x = v_x 
            vel_msg.angular.z  = w_z 

            self.velocity_publisher.publish(vel_msg) 


        p_x = pillar_dis * math.cos(pillar_ang) 
        p_y = pillar_dis * math.sin(pillar_ang) 
        p_z = 0 

        self.laser_point = Point(p_x, p_y, p_z) 


if __name__ == '__main__' : 

    x = HuskyBot()