Day #26: Practice Robot is Driving

Much progress today was made in manufacturing and assembly, and near the end of the evening the practice robot was driving for the first time.

CAD

Abhi and Richard M worked on detailing the intake assembly, with the goal of releasing all parts for manufacture by the end of the weekend. The gearbox design is still in progress, but gear ratios have been finalized and gears and timing belt pulleys selected to yield surface speeds of 17 fps on the first (top) roller, and 18 fps on the second (bottom) roller and conveyor. The higher second roller speed is necessary to clear discs from the intake more quickly when multiple discs enter simultaneously, and the conveyor must move discs back through the robot as fast as the second roller feeds them in.

Manufacturing

Students and mentors continued working on the shooter and conveyor parts that were released to manufacturing yesterday. Josh finished the conveyor frisbee back stop pins by adding a radius using the “CNC lathe file” technique. Connor, Chris and others started the conveyor middle hex shafts and conveyor bottom standoffs. Many other students cut stock material to rough lengths on the horizontal bandsaw throughout the day to keep the lathes and CNC supplied. Pat made the two different shooter shafts on the newly-functioning Monarch lathe, while Cory manufactured square plugs on the CNC to be inserted and welded into the square tubes that span the width of the intake.

 

‘CNC filing’ on the lathe

Conveyor frisbee backstop pin

 

An issue was discovered with the VEX ½” and ⅜” hex shafts received near the start of build season; many of them are visibly crooked, which is causing runout on the machined parts. E-mails exchanged about the issue with the President of VEX Robotics led to the conclusion that this was possibly an isolated incident due to the way the shafts were shipped (in a flat package instead of a round tube). More shafts are already incoming from VEX and the existing ones can be sent back for exchange.

Hex shaft held against a flat surface

Assembly

Although not all the parts that will be used in the competition gearboxes have been received yet (a few anodized gears are still missing), a few gearboxes were partially or fully assembled using substitute parts. It was discovered that the CIM output shaft spacers already made were not long enough as the WCP pinions do not have hubs like the steel pinions used in previous years, so new spacers were made.

Robert and EJ assembling the gearboxes

 

Students cleaning the gearbox shifting cylinders

Joey attaching pistons to the spider plates with Loctite

Connor and Chris installing drive chains

 

Not much wiring work was done on the competition robot as some parts (new cRIO, ribbon cables) are still missing, but enough was done on the practice robot to enable it to run. The ribbon cable going between the digital sidecar and the cRIO was added, and power was run to the analog breakout. Additionally, to enable testing, a D-Link radio and 12V-5V converter were hacked on (but will likely be moved to different locations later). Nagy and Francisco also crimped and soldered terminals to all the CIM motors.

Terminating the CIMs

The team received a visit today from Matt Pasienski, who works at one of the team’s sponsors, Ooyala, and has coached Ultimate Frisbee at the national college level in addition to holding a PhD in Physics. He spent time with the primary and backup human players, Aaron and Nagy, and helped them refine their hammer-throwing technique.

Matt coaching Aaron on how to throw a hammer

Robot driving

Final assembly and wiring of the drivebase

As the pneumatics are not yet plumbed or wired, the shifters were locked into high gear with a couple of zip-ties each. After a few false starts (the cRIO was wired to a 12V power source instead of the 24V, the analog breakout wasn’t receiving power properly, and the joystick trim tabs weren’t centered), the programming team quickly got the drivetrain running with the robot in its stand on top of a table. After calibrating the Talons, the robot was put down on the field at about 11:15pm and taken for a test drive by Abhi and a few others.

The practice robot’s maiden voyage

The drivetrain seemed very quick and responsive, and the improved linearity provided by the Talons was very noticeable. However, as the robot is currently far lighter than it eventually will be, today’s testing isn’t an effective indicator of its handling once complete. Tests were conducted with a radar gun to attempt to determine the top speed, but they were inconclusive (the gun reported 25 mph, which is too high to be correct).

• Complete manufacturing conveyor middle roller shafts and bottom standoffs

• Cut all aluminum tubing needed to be sent out for superstructure/subsystem welding on Monday

• Make drawing for superstructure plugs and machine them on the manual mill

• Begin driver drills with the practice robot

• Wire and plumb pneumatics on both robots

• Continue competition robot wiring

• build

Lab closing time: 2:00am