I keep getting the error when I try to call the service, I don’t know the reason, the class code is this, its for making the robot move in squares and stop if there is an obstacle:
#! /usr/bin/env python
import rospy
from geometry_msgs.msg import Twist
from sensor_msgs.msg import LaserScan
import time
class SqBB:
def __init__(self):
self.pub = rospy.Publisher('/cmd_vel',Twist,queue_size=1)
self.sub = rospy.Subscriber('/scan',LaserScan,self.callback)
self.action = Twist()
#self.rate = rospy.Rate(1)
self.ctrlC = False
rospy.on_shutdown(self.exitplan)
while self.pub.get_num_connections()<1:
print("waiting for publisher /cmd_vel---------")
print("-------------------------------------")
def callback(self,msg):
if (min(msg.ranges)>0.2):
self.Obst_detect=False
else:
print("Obstacle detected",min(msg.ranges))
self.Obst_detect=True
self.stop()
#self.view = msg
#self.fview = msg.ranges[89]
#if self.fview > 0.3:
# self.obstdetect = True
#else:
# self.obstdetect = False
def stop(self):
self.action.linear.x = 0
self.action.angular.z = 0
self.pub.publish(self.action)
def line(self):
self.action.linear.x = 0.3
self.action.angular.z = 0
if not self.Obst_detect < 0.3:
self.pub.publish(self.action)
for i in range(50):
if not self.Obst_detect < 0.3:
rospy.sleep(0.1)
else:
print('Obstacle deceted so we stop')
self.stop()
break
def rotate(self):
self.action.linear.x = 0
self.action.angular.z = 0.3
self.pub.publish(self.action)
rospy.sleep(5.5)
self.stop()
def exitplan(self):
self.ctrlC = True
self.stop()
def squaremotion(self):
self.line()
self.rotate()
self.line()
self.rotate()
self.line()
self.rotate()
self.line()
self.stop()
if __name__ == '__main__':
rospy.init_node('classmove',anonymous=True)
movebb = SqBB()
movebb.line
the service code is this:
#! /usr/bin/env python
import rospy
from square_service.srv import MoveInSquare, MoveInSquareResponse
from movestat import SqBB
def serback(request):
result = MoveInSquareResponse
motion = SqBB()
motion.squaremotion()
result.complete = True
return result
rospy.init_node('callsquare')
ser = rospy.Service('/sqmoveser',MoveInSquare,serback)
rospy.spin()
[ERROR] [1643277449.403695, 3055.157000]: Error processing request: ‘SqBB’ object has no attribute ‘Obst_detect’
[‘Traceback (most recent call last):\n’, ’ File “/opt/ros/noetic/lib/python3/dist-packages/rospy/impl/tcpros_service.py”, line 632, in _handle_request\n response = convert_return_to_response(self.handler(request), self.response_class)\n’, ’ File “/home/user/catkin_ws/src/square_service/scripts/square_server.py”, line 10, in serback\n motion.squaremotion()\n’, ’ File “/home/user/catkin_ws/src/square_service/scripts/movestat.py”, line 66, in squaremotion\n self.line()\n’, ’ File “/home/user/catkin_ws/src/square_service/scripts/movestat.py”, line 44, in line\n if not self.Obst_detect < 0.3:\n’, “AttributeError: ‘SqBB’ object has no attribute ‘Obst_detect’\n”]
Obstacle detected 0.11999999731779099
Obstacle detected 0.11999999731779099
then it start printing the distance but the call already gives the error in the topic
Hi @mkakram ,
The corrected code is below. I have commented where the correction were made and why. It worked on my system, do check if this solves the problem
#! /usr/bin/env python
import rospy
from geometry_msgs.msg import Twist
from sensor_msgs.msg import LaserScan
import time
class SqBB:
def __init__(self):
self.pub = rospy.Publisher('/cmd_vel',Twist,queue_size=1)
self.sub = rospy.Subscriber('/scan',LaserScan,self.callback)
self.action = Twist()
#self.rate = rospy.Rate(1)
self.ctrlC = False
#add self.Obst_detect here so that its avaialble to the class during initialisation itself
self.Obst_detect=False
rospy.on_shutdown(self.exitplan)
while self.pub.get_num_connections()<1:
print("waiting for publisher /cmd_vel---------")
print("Publsiher Ready")
def callback(self,msg):
# store laser reading in variable called self.distance_to_obstacle,
#storing only the front laser value and NOT minimum of all laser reading, since there will
#be an obstacle somewhere near the robot at all points, but not necessarily the front
self.distance_to_obstacle=msg.ranges[89]
if (self.distance_to_obstacle>0.2):
self.Obst_detect=False
else:
print("Obstacle detected",min(msg.ranges))
self.Obst_detect=True
self.stop()
#self.view = msg
#self.fview = msg.ranges[89]
#if self.fview > 0.3:
# self.obstdetect = True
#else:
# self.obstdetect = False
def stop(self):
print("Stoping")
self.action.linear.x = 0
self.action.angular.z = 0
self.pub.publish(self.action)
def line(self):
print("Moving forward")
self.action.linear.x = 0.1
self.action.angular.z = 0
# Here you were tring to <0.3 with a bool value,hence you were getting error
# if not self.Obst_detect < 0.3:
if not self.Obst_detect:
self.pub.publish(self.action)
for i in range(25):
if not self.Obst_detect:
rospy.sleep(0.1)
else:
print('Obstacle deceted so we stop')
self.stop()
break
print("Finished Moving")
def rotate(self):
print("Rotating")
self.action.linear.x = 0
self.action.angular.z = 0.1
self.pub.publish(self.action)
rospy.sleep(5.5)
self.stop()
def exitplan(self):
self.ctrlC = True
self.stop()
def squaremotion(self):
self.line()
self.rotate()
self.line()
self.rotate()
self.line()
self.rotate()
self.line()
self.stop()
if __name__ == '__main__':
rospy.init_node('classmove',anonymous=True)
movebb = SqBB()
movebb.line()
