ROS Services Quiz

Course Support ROS Basics In 5 Days (Python)
1

Hello All, I am not sure how to implement the side request to my Move_BB8 function. I am thinking of that the side = move_square.linear.x * move time (displacement = velocity * time). But I am not positive toward my thought. Here is my code shown below without the implementation of side. Appreciate anyone who could help me out!

def Move_BB8(request) :

#repeat the robot movement for request.repetitions times

i = 0

while i < request.repetitions :

    #move the robot in square

    j = 0

    while j < 4: #(j=0,1,2,3)

        move_square.linear.x = 0.2 #go straight 

        rate.sleep()

        move_square.linear.x = 0.0 #stop to attenuate the inertia effect

        rate.sleep()

        move_square.angular.z = 0.1 #make a turn 

        rate.sleep()

        move_square.angular.z = 0.0 #stop to attenuate the inertia effect

        rate.sleep()

        my_pub.publish(move_square)

        rate.sleep()

        j+=1

    i+=1

rospy.loginfo("Finished service move_bb8_in_square_custom")

response = BB8CustomServiceMessageResponse()

response.success = True

return response
1 Like
2

Hi @tonyli19970130,
Dont forget to publish the move_square each time you change it. Also using rate.sleep seems kinda weird in this instant, as you are not really dealing with a continuous loop. Rather use fixed values.
rospy.sleep(1) for example. Then you can simply change the length of the square by waiting longer after publishing the forward move command.

1 Like
3

Hi Simon, Thanks for the correction and now the robot moves perfectly fine. But when I do the quiz evaluation, it said that I did not have my services_quiz pkg compiled as shown below. I wonder if you could give me some hints on this error further. Appreciate for your time.

1
11132×481 37.8 KB

4

It is hard to say. Double and triple check your spelling and naming of packages. @bayodesegun perhaps you can take a look.

5

I forgot to include the BB8CustomServiceMessage.srv in the services_quiz package and have it complied. Now I got 10 for the quiz. Appreciate all the help!

1 Like