HamsterPythonExample1 - Revision history

Ariy: Scan

2019-06-20T09:12:19Z

Scan

Ariy at 09:14, 24 March 2019

2019-03-24T09:14:45Z

Ariy: Created page with "=== Python Example 1 === * Receive laser scan from robot to decide if free #!/usr/bin/env python import rospy from sensor_msgs.msg..."

2019-03-24T09:01:03Z

Created page with "=== Python Example 1 === * Receive laser scan from robot to decide if free <syntaxhighlight lang="python" line='line'> #!/usr/bin/env python import rospy from sensor_msgs.msg..."

New page

=== Python Example 1 ===
* Receive laser scan from robot to decide if free

<syntaxhighlight lang="python" line='line'>
#!/usr/bin/env python
import rospy
from sensor_msgs.msg import Imu

def is_free(ranges ,start_index, end_index ,min_distance):
#sub array from angle to angle
s_ranges = ranges[start_index:end_index]
#filter the array
b_ranges = filter(lambda x: x <= min_distance, s_ranges)
return len(b_ranges) == 0

def callback(msg):
if is_free(msg.ranges,160,200,0.2): print "FREE"
else: print "BLOCKED"

rospy.init_node('scan_values')

#Put your Hamster number instead of agent<number>
#The agent number is printed on the Hamster cover
sub = rospy.Subscriber('/agent14/scan', LaserScan, callback)

rospy.spin()

</syntaxhighlight>

To execute save this example in example1.py and type in the terminal

<syntaxhighlight lang="bash" line='line'>
$ python example1.py
</syntaxhighlight>

==== Ex. 1 ====

← Older revision		Revision as of 09:14, 24 March 2019
Line 37:		Line 37:

	==== Ex. 1 ====		==== Ex. 1 ====
		+	* Put the hamster in front of a planar obstacle and save a file with readings of distances to that plane
		+	* Calculate the average noise of the range scanner (take into account the angle of the reading)
		+	* Add filtering to remove peaks in the laser scan readings at each angle taking into account possible noise

@@ Line 5: / Line 5: @@
 #!/usr/bin/env python
 import rospy
-from sensor_msgs.msg import Imu
+from sensor_msgs.msg import LaserScan
 def is_free(ranges ,start_index, end_index ,min_distance):