robo_explorer: sign when moving backwards

diff --git a/scripts/robo_explorer.py b/scripts/robo_explorer.py
index 3a302cc40df33d504aa146d0a6da7b954a892de8..de755c10c38abbb52fb0261ccd2ed5689282e415 100755 (executable)
--- a/scripts/robo_explorer.py
+++ b/scripts/robo_explorer.py
@@ -2,8 +2,6 @@
 import roslib; roslib.load_manifest('roboint')
 import rospy
 import tf
-import tf.broadcaster
-import tf.transformations
 from math import *
 from geometry_msgs.msg import Twist, TransformStamped, Point32
 from sensor_msgs.msg import LaserScan
@@ -93,7 +91,9 @@ class RoboExplorer:
                # speeds
                dt = (current_time - self.last_time).to_sec()
                vx = sqrt((self.x - self.x_last)**2 + (self.y - self.y_last)**2) / dt
-               vy = 0.0
+               if (msg.output[0]-msg.output[1] + msg.output[2]-msg.output[3]) < 0:
+                       # moving backward
+                       vx*=-1
                valpha = (self.alpha - self.alpha_last) / dt
                self.x_last = self.x
                self.y_last = self.y
@@ -122,7 +122,7 @@ class RoboExplorer:
                # set the velocity
                odom.child_frame_id = "base_link"
                odom.twist.twist.linear.x = vx
-               odom.twist.twist.linear.y = vy
+               odom.twist.twist.linear.y = 0.0
                odom.twist.twist.angular.z = valpha
 
                # publish the message