a robot placing object to a circle on the floor next to the wall

I'm going to do a line following robot and it not only detect the line but also place small object like bottle to a circle on the floor next to the wall. I've known how to do line detecting part but placing object I've not had any ideas. Could you give me ideas for it? Thank you.
p/s: sorry for my bad English.

Will the circle be at a predetermined distance from the wall, or will you need to be able to actually measure the circle on the floor? If its a predetermined distance, that should be easy. Either an ultrasonic distance sensor or infrared distance measuring device would allow you to know how far you are away from the wall. If you have to locate the circle on the floor, you will need to measure its diameter and locate the centre.

Thanks @Northof49, I have to locate the circle on the floor and diameter is 5cm so how I detect the circle and design an arm to hold and place object

How does a line following robot find a circle?

Does the circle lie on the line that it is following?

@vinceherman actually this is a task in my class so your first question I confuse and the circle is not on the line

So you have a line follower. It moves forward, following a line.
And you want it to detect a circle, somewhere, not on the line.

Is the robot expected to move off of the line and move towards the circle?
What sensor do you expect to use to identify and locate the circle?

@vinceherman the circle is next to the wall so I'm going to use ultrasonic sensor and when robot detect the wall, the electric is cut and the arm place object. Is it right ?

Is your robot a line follower or a wall follower?
Your first description was that it is a line follower.

It's a line follower, but I think if robot places object next to the wall, it need to dectect the wall

I still feel that I am missing something in your task.

Your line following robot will be following a line.
Somehow, your robot will know that a circle exists. That circle will be near a wall.
Your robot will then place an object in the circle.

How will your robot detect the circle?
Will the circle be near enough to the line that the robot can drop the payload in the circle while still following the line? Or will the robot need to leave the line and navigate to the circle?

I think it might be useful if you can show us a diagram of the area including the line and the position of the circle relative not only to a wall but to the line that you're following.

Or are there two completely separate tasks ?

  1. Follow a line
  2. Find the circle perhaps by following a wall and then place something on the circle.


Is it possible the circle is to be ascertained by the line follower?

The robot must place a small plastic bottle ( approximatrly 10 cm in height and 3,5 cm in diameter) next to a wall, at the end of the course so it touches a 5 cenrimeters semi-circle loacted next to the wall, so the robot needs have a mechaism that can carry and release the bottle in front of the robot, next to the wall, a sensor or sensors to detect the wall, and a control system that will stop robot and release the bottle

That is a good improvement of the objective.

at the end of the course s

The helps us with how you are going to get to the circle. I think there are still some open questions, but we will tackle those and move forward.

Is this a school assignment? Often school assignments like this come with written specs. It would be helpful for us to see those specs.

You have described that the circle is at the end of the course, but there are still questions on what that means. Does the course (the line that your robot will follow) end with the circle being part of the line like this?


Is it enough to follow the line until your sensor detects the appropriate distance from the wall and then drop the payload?

Yes, it is my task in class. I asked my teacher and he said: “ the circle is at the end of the line, next to the wall”, I think your diagram is right.

If my diagram is right, I see 2 possible solutions.

  1. Use the 3 optical sensors to detect the circle. If your robot is centered on the line, approaching the circle will create changes in both side sensors. Then drop your payload.
  2. Use a sensor (ultrasonic? IR) to look for an obstacle in front of you at a specified distance. Then drop your payload.

Maybe a combination of both methods?
Method 1 by itself might be unreliable. It depends on the simultaneous detection by both side optical sensors. This would not be the case if the robot is not well centered on the line.

My vote? Lay out a course and try it out!

Do a search on the internet using your favorite search engine for "Arduino optical flow sensor." The Arduino optical flow sensor can detect the line and the circle.