Key Features:

  • Single system
  • Prefabricated urethane belts
  • Controlled speed through use of encoder
  • Custom made, hardened rollers
  • Pneumatic opened door
  • Supersonic range finder score assist

Specifics:

  • Two Cims
  • Two 10 tooth sprockets
  • Two 34 tooth sprockets
  • #25 chain
  • 34:12 reduction from motor to roller
  • Two 10", ¾" bore pneumatics
  • Over 2500" of ¼" urethane cord
  • 182" of 1½ " schedule 40 PVC
  • 170" of 1/16" wall box channel roller supports

The conveyor system was where the team thought we would have the most trouble. In the past, 234 has not done particularly well when it comes to picking up, possessing, and ultimately scoring small, round game elements. We designed overly complicated, slow mechanisms which turned out be less effective than simpler devices. Knowing our short comings, we focused on our conveyor system more than any the other type of system.

After developing some general ideas, the team studied previous successful designs from the 2006 FIRST game. The game elements are fairly similar to this year. The major consistency throughout many of the teams was the use of urethane cord. However, Cyber Blue had limited experience using the strong, durable cord. After several strength tests and material comparisons, the team decided that the urethane cords were indeed the best option for a powerful roller-conveyor system.

Now that the material was decided, we had to develop a general shape. We once again looked to the past. Vertical lifts take up the least amount of space, but it is harder on the motors to lift. A horizontal lift is easier on the motors but consumes a considerable amount of space. After several prototypes and many hours of testing, Cyber Blue came up with a 60 degree, double conveyor system. The double conveyor system was conceived of off the simple concept that if you have two conveyors, you will have twice the power and therefore twice the lifting capability. By keeping the two rollers 8" apart, it gave us an exceptional compression on the moon rocks while keeping the system loose enough that it wouldn't bind or jam. An added aspect of the robot was the constant agitation produced by extended conveyors in the hopper area. From past years we have learned that once game elements are allowed to settle, they tend to jam. To counteract this we devised a very simple solution. Movement. It sounds like a simple concept, but once we started to implement it into our prototypes we noticed a considerable improvement in capacity as well as overall scoring. Our final design involved adding an addition horizontal roller to form the bottom the hopper. It was a simple solution to a very large problem.

To make the system rigid we incorporated simple PVC piping that is used very commonly throughout the FIRST community. The adaptations we made to the PVC were not very common, however. At first glance the PVC is very strong and can even be said to be unbendable, but after preliminary tests were done with the belts we noticed a significant bend in the tubing. This is because of the high level of pressure due to the urethane belts. To neutralize this affect we inserted 1/16" wall Aluminum box channel to help strengthen the rollers. To eliminate the weight addition from the channel, we shortened and drilled holes into the 1¼"PVC couplings, which serve as our guides for the belts.

The rollers are driven by two Cims. Each of these Cims is chained to one roller. These rollers are then connected by the urethane belts. This gives us redundancy in the fact that even if we lose one roller, we can still pick up and score. Attached to each chain is an encoder. These encoders are used to add power to the motors if they happen to slow down. Essentially, when the robot starts gathering moon rocks, the compression on the rollers slows down the system. Since the motors are only running at approximately 75% power, we just send more current from the battery. This ensures we have a constant speed in which the moon rocks are flowing. Now we had the materials we were going to use, and we even had the outline of what the conveyor would look like. However, we still needed the intake and dispersion aspects of the robot. The former was quite simple. Because of the double roller system, we were able to extend belts' length until there was an 8" vertical gap at the front of the robot. The scoring mechanism was a little more complicated. We looked at several options: motors, pneumatics, servos, and even a garage door style of mechanism. The simplest, lightest option was pneumatic, but to use this option, we had to add the air compressor as well as several reservoirs. This added weight was compared to the total of the other options. It actually helped having the compressor on the robot because we used its weight to offset the weight of the battery. To help open the pneumatic door, we installed two supersonic range finders. These sensors send our bursts of signals (sound) and then use the time it takes for the signal to travel back to judge the distance. This is much like echo location used by bats. When the trailer is within range, LED lights glow on the driver station to inform the operator that the trailer is within range.

The hopper can hold up to twenty moon rocks. It can score it's total payload in under two seconds. It meets all of our goals and even surpassed them. It incorporates several sub-teams, several engineering practices, and several lessons learned.