NXT-Spy – First successful implementation of the ball finding / catching.

Posted on February 9, 2011 by Arnaud Lejosne

Today is a big day for this project, the robot now manages to find balls and to catch them on its own.
In fact, all last week problems are solved: A ball of Blu-Tack solved the balancing problem and the solution I thought about last week to solve the lag problem worked quite well, in fact, apart the fact that the robot is moving very slowly, it manages to find balls quite efficiently.
So here is the video that shows the success of the experiment (I accelerated the video of 200% because the robot is operating very slowly):

[yframe url=’http://www.youtube.com/watch?v=arTqjEFSyMQ’]

Today, I also did some testing in the white environment and figured out that Data Matrix 2D barcodes worked way better than the QR code as they are way less complex. I am even wandering why I chose QR codes the first time… maybe because it is more beautiful 🙂

Supervisor’s comment:

Well done; how about finding the Blue and Red corners? They work most of the time but because the flag goes out of view it makes it hard to know when you have reached the corner.
Has also written up the report so far as he is not here next week. So he has done two week’s work in one!!!!

NXT-Spy – First tests of the ball finding / lifting part of the experiment

Posted on February 2, 2011 by Arnaud Lejosne

Today, I have been able to test for the first time the robot’s controller in an ideal environment. This experiment cannot really be called as a success as I have faced a very disturbing issue: even when we are working in the best conditions (for this experiment, I worked with a Wi-Fi ad-hoc connection between the phone and the PC instead of using a router between the two), the images rate is still too low to be able to easily control the robot.

To solve this problem with the current configuration, I think that the best way is either to try to predict the position of the ball based on the speed of the robot or to simply slow down the speed of the robot to a minimum.

A second minor problem is that as predicted, the robot is too heavy on the phone’s side, the solution is obviously to put a weight on the other side of it to counterbalance.

But there are not only bad news: automatic control of the robotic arm works like a charm: as soon as the ball is touching the arm, it lifts it.

NXT-Spy – Robotic arm testing

Posted on January 24, 2011 by Arnaud Lejosne

Now that the robotic arm was engineered, I needed to do test it in real conditions (controlled from the PC over the phone) and see how well it can work when the robot is actually going forward on a ball to pick it. After some slight modifications on the arm to optimize it, I managed to make to arm working perfectly. Here is a video I did on my kitchen table that shows the result of the experiment.

[yframe url=’http://www.youtube.com/watch?v=Itx_N-mG9TM’]

Supervisor’s comment:

Very impressive, we now know that the robot can pick up and deposit a ball.
Has done some writing but has been ill.
Jon has got all the bits needed to build the environment.
Robot starts at home position finds a single ball, picks it up and returns to the home position.
Then add the ability to deposit ball in correct corner. (This will perhaps be the biggest challenge in robotic control.
Then add a second different coloured ball and deposit it.
Then many balls.