Ask Your Question
0

While loop for Ros Python Rosserial [closed]

asked 2018-03-31 09:47:31 -0600

RosStudent gravatar image

updated 2018-03-31 11:53:07 -0600

What can i do to avoid Ros from losing connection to arduino when using a while loop?

i have tried many methods and nothing worked.

When the program stays long in the turnToNorth position the rosserial connection is lost

Example of snippet code below:

#!/usr/bin/env python
import rospy
import time
from std_msgs.msg import String
from std_msgs.msg import Int32
from std_msgs.msg import Bool
from sensor_msgs.msg import Range
from marval.msg import l298n as l298n
from marval.msg import lsm303 as lsm303

subMotor = l298n()
subServo = String()
subStart = Bool()
motorData = l298n()
subCompass = lsm303()


motorSpeed = 23
irEdgeDistance = 1.0
usDistance = 0.15
moveAngle = 20.0
intervalTime = 0
startDirection = 0.0

def subStartC(data):
    global subStart 
    subStart = data

def subCompassC(data):
    global subCompass 
    subCompass = data

#Publishers
pubMotor = rospy.Publisher('motor_data', l298n, queue_size=10)

#Subscribers
rospy.Subscriber('start_data', Bool, subStartC)
rospy.Subscriber('compass_data', lsm303, subCompassC)


def moveRobot():
    turnToNorth()

def turnToNorth():
    global startDirection
    while (int(subCompass.angle) != int(startDirection) and not rospy.is_shutdown()):
        motorData.enA = motorSpeed
        motorData.enB = motorSpeed
        motorData.in1 = 0
        motorData.in2 = 1
        motorData.in3 = 1
        motorData.in4 = 0
        pubMotor.publish(motorData) 


def startRobot():
    #initiate node
    rospy.init_node('moveRobot', anonymous=True)
    rate = rospy.Rate(5) #hz
    while not rospy.is_shutdown():
        if(subStart.data == True):
            moveRobot()  #starting the robot movement
        else
            stopRobot() 
        rate.sleep()


if __name__ == '__main__':

        try:
            startRobot()

        except rospy.ROSInterruptException:
            pass`

Part 2 :(EDIT)

def turnToNorth():
    global startDirection
    while True:
        if(int(subCompass.angle) == int(startDirection)):
             break
        else:
               motorData.enA = motorSpeed
               motorData.enB = motorSpeed
               motorData.in1 = 0
               motorData.in2 = 1
               motorData.in3 = 1
               motorData.in4 = 0
               pubMotor.publish(motorData)
edit retag flag offensive reopen merge delete

Closed for the following reason the question is answered, right answer was accepted by RosStudent
close date 2018-04-01 02:20:27.283004

Comments

i have tried many methods and nothing worked

What have you tried and what were the results?

jayess gravatar imagejayess ( 2018-03-31 11:10:08 -0600 )edit

When in the loop after some seconds rosserial disconnects from arduino and the program keepa looping and cannot terminate the program.

I also tried while True: and add a break when condition is met but still same issue.

RosStudent gravatar imageRosStudent ( 2018-03-31 11:22:20 -0600 )edit

Can you please update your question with a copy and paste of the code that you've tried and the results?

jayess gravatar imagejayess ( 2018-03-31 11:25:33 -0600 )edit

Pasted snippet of code and same result

RosStudent gravatar imageRosStudent ( 2018-03-31 11:53:20 -0600 )edit

2 Answers

Sort by ยป oldest newest most voted
1

answered 2018-03-31 22:09:41 -0600

fergs gravatar image

There may be other issues, but the thing that jumps out to me is this:

In your function "turnToNorth()" you have a publish call in a while() loop, with no sleeps. This is probably running at 10khz+, and overflowing some buffer somewhere (you can't possibly shove that much data down a serial connection). At least put a rospy.rate() or time.sleep() in that loop, so that it runs no more than maybe 25hz to start with.

edit flag offensive delete link more

Comments

I'll will do that as I have other functions similar to the turnToNorth. Furthermore what happens if it stays for around 10sec in a while loop? Should there be an issue?

RosStudent gravatar imageRosStudent ( 2018-03-31 23:58:55 -0600 )edit
0

answered 2018-04-01 02:19:53 -0600

RosStudent gravatar image

Yes creating the below with each publisher in a while loop fixed the issue.

r = rospy.rate(5)

while True:
    pub.publish(data)
    r.sleep()
edit flag offensive delete link more

Question Tools

Stats

Asked: 2018-03-31 09:47:31 -0600

Seen: 731 times

Last updated: Apr 01 '18