Disc Foam, Limit Switches, Hopper Side-Skirts, Compass Mount, Front Channel - Matt Mannino

With 1 week left, we finally started to put together most of the vital pieces to the robot.  We ran into the issue where spacing on the discs was very critical, and the slightest adjustment would either make them grip the balls too much, or not enough.  So the addition of foam on the inside of one disc would help compensate for the variation in spacing.  

Green foam on inner disc

Another vital part of the ball collection mechanism is the hopper.  We cut and mounted the hopper ramp, but there still needed to be some sort of walls to keep the balls from falling out.  So we cut and mounted some 1/16 inch aluminum sheet metal for the side-skirts. They are also notched at the electronics box hinges to still allow access.

Side-skirts for hopper

The other mechanism we added was a front channel to help channel the various balls into the collection mechanism.  It is comprised of Vex c-channel about 12 inches long each.  They are mounted with a piano hinge on the inside of the chassis and with a slotted L-bracket on the outside.

Front channel (far right)

 The additions to allow the robot to realize it has backed in to the home station are two limit switches at the very back of the robot.  These will allow the robot to perfectly line up with the home station.  Another limit switch we added was for the trapdoor so the robot will be able to open and close the door accordingly.

Limit switch on back for home station

Limit switch on top bracket of trap door mechanism

While coding, I realized that any metal in the immediate vicinity of the compass module would cause erratic readings.  To address this, we had to come up with a mount that was void of metal for the most part.  We cut a piece of 1 inch diameter pvc to about 7 inches for the main mount. To hold the compass module in place, we used a piece of fairly rigid foam and inserted the connectors for the compass.  I also fished the wires through the pvc.

Side view of compass mount

Top view of compass mount

Trap Door and Electronics Box Work - Matt Mannino

With more items on our to-do-list left, we are finally finishing them one at a time.  We assembled a "trap door" for the hopper on the back of the robot.  This allows the balls to be dumped out from the hopper into the home station once its path is completed.

Trap Door closed

Trap Door opened

We also added some smaller features to the electronics box that protects and houses the electronics components.  There are two metal clasps, one on each side, that hold the box shut.  There is also a hinge that locks the box in place while it is open.

Metal clasp to hold protective box shut

Hinge on left to keep box open for working on electronics

Final Robot so far

Drive Motor Configuration, Wiring, and Disc motor - Andrew Baden

Over the past few days, we have completed many of our remaining tasks to get the project completed by April 25th.  For starters, we finally have the correct motors in place for our drive train, and have the chains correctly laid out to the point that we shouldn't need to reconfigure them again.

The correct drive train motors mounted and wired

We have also completed most of the major wiring to for devices such as the motors, motor controllers, battery, switches, indicator light, and the Arduino motor controller.

All the major components wired and placed

Emergency and main power switches, and emergency light mounted and wired

Indicator light operational

Now that we have the discs cut and hubs put on them, we can now finalize the mounting solution for them. The mount we used before was too flimsy, and was difficult to mount the motor to.  The mount we have now houses a compound gearbox because the motor we chose that would have enough power, runs too fast. This compound gearbox puts the discs spinning at an effective speed. The mount we have now also uses angle aluminum from the Gears Ed. kit to allow for a more stable platform, and reduce the flimsiness the previous mount had.

Compound Gearbox

Over the next few days, I would like to finalize the hopper's position, and create the channeling plows on the front for the ball collector.

Disc Machining and Mounting - Andrew Baden

Yesterday I finally got the plastic discs cut out on the CNC machine, with the help of Dr. B.  Each disc has a bolt pattern to mount a hub to, so we can mount the discs themselves to a shaft.

The discs being ready to cut in the CNC machine

More perorations for the discs

Discs being cut

Discs cut with hub attached

Discs attached to chassis

Our next step is to figure out a way to power these discs, and to put an abrasive or rubber like material on the discs to better pick up the balls from the ground.