Havana
2018's robot, Havana, was built to compete in FIRST's challenge: RELIC RECOVERY presented by Qualcomm. Our robot was able to pick up glyphs (6'' cubes) and place them into the cryptoboxes (scoring element) in specific patterns. Our robot could also pick up the relic and put it into the third recovery zone. In addition, it was able to drive itself up onto the balancing stone.
Drivetrain
Since it was necessary for Havana to go up onto the balancing stone, we decided that if we had a ramp in the front we could have four-inch wheels. And if we didn’t have a ramp, we could use six-inch wheels. But if we used a ramp, it had to be able to retract to fit into the size limit. We eventually went with four-inch wheels with the drive train plates cut at an angle so they acted as a ramp to assist the robot with driving up the balancing stone. For the type of drive, we decided that we wanted a chain drive. A chain could power wheels using sprockets. Sprockets were generally the most effective in transferring power because it did not run into the problems that gears and direct power did. It could also allow the motor to be placed at a greater distance away from the wheel, allowing for more liberty of how the drive train could be designed. For the drivetrain, we decided to use a mecanum drive. The mecanum drivetrain utilized 4 mecanum wheels that were placed in tank drive position. Unlike omni, mecanum wheels allowed for 70% pushing power forward and 30% pushing power to the side. This was useful for playing defense or getting up obstacles.
Gylph Manipulation System
The blocks in the game Relic Recovery reminded our mechanical lead of an FRC game Recycle Rush. He initially planned to create a collector with wheels collecting the glyph but soon realized it would be too complicated and we needed to keep it simple silly (KISS). We then realized the mechanism was too slow and we replaced our standoff mechanism with a fully 3D printed spool. Our fail safe for the glyph lifting mechanism could be found in the two spools/strings we used to lift the glyph grabber. If one string broke, we still had another string to lift the mechanism. We also included a third spool to pull our glyph grabber down if one section of the rev extrusion had high friction.
Relic Extension System
We focus on the relic because it would be the tie breaker in high scoring matches.
We planned out our design with screen shots and hand drawings of Wizard.exe’s robot design. The team at this point had KISS embedded into their blood and chose a simple stringed rev extrusion extension with a single action servo to collect the relic. The spools took a long time to 3D print so we separated each construction into 3 parts.
Jewel Manipulation System
The jewel manipulation system was essential for autonomous. Our mechanism exemplified KISS. It was a single servo lowering a color sensor to read the jewels. This allowed the team to have a fully functional autonomous at the expense of very little resources. Our fail safe for the jewel arm was utilized when we looked for the jewels in autonomous. If we are unable to read the ball, we would go back and read it again.
If we still could not read the ball color, we would move on without pushing a ball off blindly as we could risk giving an advantage to our opponent.