So I have a problem that asks me to rotate my robot facing the wall. I created a callback function for my subscriber and I am trying to compute its values in the function. Here is the code:
def callback(msg):
r = list(msg.ranges)
minimum_value = min(r)
print(minimum_value)
index_minimum = r.index(minimum_value)
rounded_min = round(minimum_value,3)
print('min index',index_minimum)
if index_minimum > 360:
twist_instance.angular.z = 0.05
else:
twist_instance.angular.z = -0.05
while round(msg.ranges[360],3) != rounded_min:
print('rounded min', rounded_min)
print('front ',round(msg.ranges[360],3))
print('index naya', index_minimum)
pub.publish(twist_instance)
rate.sleep()
twist_instance.linear.x = 0.1
twist_instance.angular.z = 0
while round(msg.ranges[360],1) >= 0.3:
pub.publish(twist_instance)
rate.sleep()
twist_instance.linear.x = 0
pub.publish(twist_instance)
if __name__ == '__main__':
rospy.init_node('findwall_node')
sub = rospy.Subscriber('/scan', LaserScan, callback)
pub = rospy.Publisher('/cmd_vel', Twist, queue_size=1)
twist_instance = Twist()
rate = rospy.Rate(1)
my_service = rospy.Service('/find_wall', findwall, my_callback)
rospy.spin()
I am printing out the values just for a reference. Here the r = list(msg.ranges) has index range from 0 to 719 and they represent laser values from 0 to 180 degrees respectively. As the robot rotates the values will change at the same time but thats the problem I face. They do not!. I printed out the values in the loop and the values for each of them always remain constant. Can you help me understand why that is?
I think it is because you are using a loop inside the callback, in the line while round(msg.ranges[360],3) != rounded_min. Then, the callback gets "stuck", and it is called only once, causing msg.ranges to remain constant. However, I am not able to test your code just now.