2009:Mechanical 2.17.2009

Discussion moved to: http://www.penfieldrobotics.com/wiki/index.php?title=Talk:Mechanical_2.16.2009

Kims Notes

I stopped in this morning, and wanted to update the mechanical teams on what was currently in progress. Larry, Theo and Shauna got there at 6am this morning to start working, I got there about 7:30, and Ted & Rika arrived around 8:15.

1. The burnt RS-545 motor from the back conveyor was removed & replaced with a fischer Price motor (I think last night), but then this morning we switched it back to an RS-545 (realized we already had 2 Fischer Price setups)

2. The Fischer Price & gearbox was removed from the top shooter assembly, and is now mounted in place for the back conveyor so both conveyors now have Fischer Price Motors with the good pinion setups (we found that the pinions were cracking because the FP shafts were just slightly larger, so Larry turned down the shafts and pressed the pinions on this time - and they even sound much better!!)

3. I ordered 10 more pinion gears, and an RS-385 25:1 transmission. They did not have any more of the 545's so we can take the mounting plate from the extra transmission (or one if we damage it), and the 25:1 planetary gearboxes are the same, so we just move the transmission plate over and have a replacement gearbox. The new gearbox is strictly as a spare anyway.

4. They were moving the RS-545 motor & gearbox up to the top assembly as I left. We also removed the sprockets, and are replacing them with a 32:16 to be able to double the speed. It looked like the 32 would still fit with everything staying exactly in the same spot.

5. The lexan panels were being moved to the inside when I left. We will start off securing them will velco, and try to test it if possible to see if it still bows, if so more velcro can be added, and if that doesn’t completely fix it, we can add stiffening lexan, crosswires or other methods that were mentioned last night.

6. The back pulleys & belts were being moved to one side to match the front and test the multiple belts theory. It is assumed there is still too much "squish" between the pulleys, but it should work for proof of concept.

Tom C took notes from our design meeting last night, and Dave Vadas had some task lists organized, and took down all of our weights and dimensions. (Tom & Dave, if you can get these posted on the wiki, that would be great!!)

http://www.penfieldrobotics.com/wiki/index.php?title=Mechanical_1
Basics from what I remember:
Top Shooter - Works well, maybe just needs to be sped up, we can replace with 2:1 gearing.
Collection - Chicken Plucker/Pool noodle setups work well, no real changes needed? Need to make sure we have all the red/black stiffer pluckers in all of the spots. Even if pluckers go under belts, they don’t seem to unseat them like the VBelts, and even if belts fall off, pluckers are stiff enough to get the balls up into the upper conveyor system.

Dividers - seemed to work well, but impact ball storage, and might not be needed, can build up real ones, but not use if not necessary on practice day.

Conveyor Belt - Belts falling off seem to be due to side loading, solution is to add more belts. Moving pulleys, or making new shafts out of larger diameter aluminum tubing or PVC are options to get more belts on there. Still need to discuss more on if we will use divider or just full across set of belts.

Mechanical, as we head into our Fix-It time, please make sure you have familiarized yourself with the rules:

WITHHOLDING ALLOWANCE – A limited amount of FABRICATED ITEMS that are permitted to be
withheld from the ROBOT shipping requirements (specified in Section 4.10 and Rule <R25>) and
retained by the team following the shipping deadlines. These items may then be hand-carried to a
competition event by the team. The OPERATOR CONSOLE is automatically included in the
WITHHOLDING ALLOWANCE. Beyond that, the incoming material maximums specified in Rule
<R36> limits the amount of FABRICATED ITEMS included in the WITHHOLDING ALLOWANCE.

FABRICATED ITEM – Any COMPONENT or MECHANISM that has been altered, built, cast,
constructed, concocted, created, cut, heat treated, machined, manufactured, modified, painted,
produced, surface coated, or conjured into the final form in which it will be used on the ROBOT.
• Example 1:A piece of extruded aluminum has been ordered by the team, and arrives in a 20-
foot length. To make it fit in their storage room, the team cuts it into two ten-foot lengths. These
would not be considered FABRICATED ITEMS, as they have not been cut to the final length in
which they will be used on the ROBOT.
• Example 2: A team designs an arm mechanism that uses gears with a 1/2-inch face width.
They order a 12-inch length of gear stock and cut it into precise 1/2 inch slices. They do not
bore out the mounting bores in the center of the gears. The slices are now considered
FABRICATED ITEMS, as they have been cut to final size, even though all the machining
operations (the center bore) may not yet be completed.

<R26> During the period between the shipment of the ROBOT and the competitions: During this period, all teams may manufacture SPARE, REPLACEMENT, and UPGRADE PARTS, and develop software for their ROBOT at their home facility.

A. Teams may manufacture all the SPARE, REPLACEMENT and UPGRADE PARTS theywant.
B. There is no limit to the amount of time that may be put into this effort, other than via the realities of the calendar.

C. Teams may continue development of any items retained under the WITHHOLDING ALLOWANCE, continue to work on them during this period, and then bring them to the competition events.

D. The total weight of the FABRICATED ITEMS (SPARE, REPLACEMENT, and UPGRADE
PARTS, plus all WITHHOLDING ALLOWANCE items) worked upon during this period and
brought to the competition event(s) must not exceed the limits specified in Rule <R36>.
The primary intent of this rule is to allow teams to withhold the ROBOT control system, the
OPERATOR CONSOLE, and selected relevant subsystems, and access them after the
shipping deadline. This will allow teams to have the maximum time possible prior to each
competition event to develop and complete the software for their ROBOT while maximizing
the potential to understand and use the capabilities provided by the new control system.

<R36> Teams may bring a maximum of 40 pounds of custom FABRICATED ITEMS (SPARE
PARTS, REPLACEMENT PARTS, and UPGRADE PARTS, plus all WITHHOLDING
ALLOWANCE items) to each competition event to be used to repair and/or upgrade their
ROBOT at the competition site. All other FABRICATED ITEMS to be used on the ROBOT
during the competition shall arrive at the competition venue packed in the shipping crate with
the ROBOT.
• Exception: the OPERATOR CONSOLE is not included in the incoming parts weight restriction.

OPERATOR CONSOLE – the Driver Station unit provided in the FIRST Kit Of Parts, and any
associated equipment, control interfaces, display systems, structure, decorations, etc. used by the
PILOTS to operate the ROBOT.

Larry's Notes from Just before Ship

As for Tuesday we did observe that the belts being closer together significantly decreased the about of times the belts fell off and increased pickup efficiency. The only times we threw the belt was due to there being too many balls in the belts and the shooter wheel not moving. There will need to be some adjustments with the lexan to prevent jamming.

We may still need the back divider due to ball jamming but the front may be fine without the divider as long as we implement the changes with more belts closer together. The chicken pluckers seemed to go a great job of picking up the ball. Even the side without the belt was able to fling them up to the second stage of pluckers without much problem.

Both motors on the belts are now the Fisher Price motors. We tried to run a 2:1 on the spinner motor to increase speed but there was not enough torque to shoot the ball. So we went back to a 0.93:1 for now. Maybe we can get a ratio greater than 1 but less than two that will work. Maybe a 1.5:1.

The balls kept on getting stuck on the spinner mount that was hanging down so Ted put together some thin lexan guards that seemed to help a little bit but things would still get caught from time to time.

Balls still go caught on the back bar of the rear trap door sometimes due to the lexan bowing out the back of the robot. I think some wire behind the lexan will keep this from occurring.

So to summarize here are the major things that need to be fixed and my guess as to priority. Robot Belt assembly (using one of the determined redesign methods that were discussed Monday night) Shooter Wheel Speed (some optimized gearing ratio torque vs.. Speed) Balls getting stuck in hopper (maybe divider or more rigid backing will fix) Balls getting stuck near shooter assembly (reduced due to Ted's fix but still occasionally happening)