Friday, December 13, 2013

LCD display added and finally working correctly



This video shows the LCD successfully incorporated into our project.

The LCD component needed a lot of troubleshooting.  To set the contrast, we had to use a diode from the Arduino kit instead of a potentiometer as suggested on the Arduino website.  Luckily the contrast came out perfect with our diode.  The LCD display now displays the current angle the release arm is set to in real time.
The LCD display fades a little bit while the servos are drawing power, but regains perfect contrast once the servo positions are set.

There was a bit of error near the top end range of angle (70-90 degrees) as the actual release angle control arm will not move much in that range while the potentiometer and the displayed angle will change normally.  We were able to fix this problem by changing the scaling of the potentiometer input and servo output in the coding.  The lower limit of the angle control arm has also been set so that the arm does not hit the base any more.

After this video was taken, the coding was updated so that the display also shows "Team Catapult!" when first being turned on and initializing.  Then, when the angle is done being changed, the phrase "Ready to Fire" will also be displayed along with the current angle of the release control arm.

The coding used in this video is "Catapult 3" in our Google Drive coding folder.
https://drive.google.com/folderview?id=0BxD61BKSCEuLSzRaOGFMbDl5c1E&usp=sharing

Also, the issue of inconsistent max pull of the spring has been fixed by using shorter solid wires with lower resistance instead of the braided ones in the Arduino kit.  It seemed that the lowered resistance in the circuit allowed the servo the little bit of extra juice to consistently give maximum spring pull travel. There are still some kit wires on the board for the LCD display function, but they will be replaced in the future.

Once we get the 3D printed parts and acrylic sheets, the button and potentiometer will be put on the acrylic sheet control panel and the temporary nails in place of the spring hooks will be replaced.  The catapult arm will also have a bowl for the shots to sit in.


-Team Catapult

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