2012 – Rebound Rumble
Robots shot small basketballs on three different levels of varying difficulty in order to score points. At the end of the match, robots balanced with alliance partners on colored alliance bridges, or balanced on the Coopertition Bridge in the center of the field to earn Coopertition points. This year, Coopertition was just as important as winning in determining your final Qualification Score.
Our robot, named Rose in honor of longtime mentor Rose Barra, was a well-built competition robot. With it, we were able to win the Northeast Utilities Regional, as well as compete at the Manchester Regional, and on the Archimedes Field at Championships. Rose has several unique, key features detailed below. Hopefully they’ll help inspire you with new ideas for your team’s robot!
Chassis and Drivetrain:
Rose’s chassis was welded from 1-inch aluminum stock. The aluminum used is hollow to because of weight restrictions, and it’s thickness ranges from one-eighth to one-sixteenth of an inch thick, due to support considerations. Over 300 welds were made on the chassis. Lightening holes were used to additionally conserve weight.
Strategic analysis of the game had shown that swerve, holonomic, or omni driving was not needed in order to achieve success. Instead, a standard four-wheel drive was selected with 6-inch wheels from the 2012 Kit of Parts. To power the drivetrain, a total of four CIM motors were used; two on each side, geared with a CIMple Box. Chains were used to transmit the power from the motors to the wheels.
Rose used a unique, dual-sided collector. Quarter-inch polyurethane cord belts wrapped around 2 custom-made, aluminum axle-pulleys on each side. This system ran at 1000 RPM, which was matched the linear speed of the robot. An angle in the pan centered balls as they entered. From there, basketballs were transferred to the throat before being ejected by the shooter. To ensure compression on balls as they were transferred from both sides, a latex rubber sheet was used in between the two sides, forming a wall with just enough flexibility to maintain compression.
Rose used four flywheels on two axles to shoot the basketballs. The 6-inch diameter flywheels were chamfered at 60 degree angles, and powered by BaneBots motors in a CIM-U-LATOR gearboxes. Encoders and Jaguars were used to provide speed control via CAN bus.
Horizontal angle control was achieved with a turn table, with a maximum of 200 degrees of travel. The turn table itself was machined as a large sprocket for #25 chain, and was driven by a motor, with CAN bus position control.
The bridge actuator was conceptualized as a reverse cowcatcher in order to use the weight of the robot to lower the bridge. Many iterations of prototyping were used to finalize a design as various flaws were discovered: the original 16-pound estimate for the force required to lower the bridge was overly conservative, for instance. Our final design is a welded appendage that acted as a wedge. As a window motor was used to drive it down, a servo motor was used to drive a pin into the chassis, anchoring it. Orange tape was used to help maximize visibility for drivers.
New and Interesting:
It was the most sport-like game yet! Because of the easy-to-understand game, Rose will be used for years for demonstration purposes.
Dr. Woodie Flowers, co-founder of FIRST and inspiration for the Woodie Flowers award, visited our pit in Connecticut! He picked up a few more signatures for his denim jacket, and graciously signed some of our team jerseys in return.
Team 20 at the Hartford, CT regional quarter finals.
2705 teams competed in 50 regionals.
2013 – Ultimate Ascent
Robots shot frisbees into different goals to score points. At the end of the game, robots needed to climb the pyramid on their side of the field to score points. By “ascending” anywhere from 1-3 rungs of the pyramid, teams could score different amounts of points.
Our robot was named Cathy in honor of our mentor, Cathy Wickswat, who passed away the fall preceding the 2013 season and was exceptional in competition. Her reliability in competition earned Team 20 two Quality Awards at both our regionals. With her, we were Finalists at the WPI Regional, Undefeated 1st seed and champion at the Connecticut Regional, as well as 10th seed and Quarter-finalist in the Archimedes division at World Championships. Cathy has several features that made her phenomenal in competition that are detailed below.
Chassis and Drivetrain:
Cathy was our first robot to use a West Coast Drivetrain (WCD). A WCD is a drivetrain built for reliability and maintenance. The wheels are cantilevered on the outside of the frame to allow for easy removal and replacement. Our 4-CIM six-wheel drivetrain is built to be both reliable and efficient, being able to drive even if a drive chain were to break due to the center wheels being powered directly from the gearbox.
The frame itself was welded together from 2×1″ and 1×1″ hollow aluminum tubing, and was both light and durable, taking hard hits throughout the season. The six-wheel drivetrain has a slightly dropped center wheel to allow for a tighter turning radius, and the encoders mounted on the drivetrain allow for accurate movement in autonomous.
One of the mechanisms that separated Cathy from many other robots in the world was her collector. As one of the few robots at each of our regionals that opted to collect Frisbees from the ground as opposed to the feeder stations at each end of the field, Cathy was one-of-a-kind.
When prototyping and designing a Frisbee collector at the beginning of build season, many ideas were given as possible collection mechanisms- most comical was a plunger that was shown in the game animation. In the end, after much prototyping using VEX wheels and plywood, we arrived at our roller-intake. The intake uses 3″ Banebots wheels and polyurethane cord hooked up to a Banebots motor and gearbox to grab the frisbee and pull it onto our “scoop”. The scoop was mounted on wooden skis to help it traverse the bumps on the field without catching the seams in the carpet. With this, Cathy could pick up Frisbees from nearly anywhere on the field, as well as perform an autonomous routine involving more than the three pre-loaded Frisbees each robot could start with.
After much prototyping, Cathy was outfitted with a 66 degree circular, rotary shooter. This allowed for our linear hopper and transport system (detailed below), as well as accurate shooting from the pyramid. To propel discs, a CIM Motor spun up a 2010 Kit-of-parts “wheelchair wheel” flywheel. Encoders were used to control the flywheel speed using a bang-bang algorithm. Using this shooter, Cathy had 95% accuracy at our first regional, WPI. This was due to both Cathy’s well-built shooter, and our strategic decision to have only a few shooting locations Cathy could specialize in; Cathy only has two shooting positions. This “hard stop” allowed Cathy to get in position to fire and shoot all four frisbees in a matter of seconds.
Hopper, Transport System, and other features:
Cathy’s hopper was built to be impossible to jam and as simple as possible. By lining up the frisbees side-by-side, one-by-one, we were able to avoid having any frisbee jams the entire season. The frisbees moved through the hopper by a polyurethane belt on the side of the hopper. During our test-and-tune process, we discovered that sometimes the belt would slip, and the frisbees wouldn’t move up the hopper. To prevent this, we used electrical tape to create “bumps” for the frisbee to be moved by on the belt. It worked very well, serving to prove that a complex problem can have a very simple solution. To index the frisbees, Cathy has two pneumatic cylinders mounted on the shooter tray. One is used as a gateway to block the frisbees from shooting early, and the other is used to shoot the final frisbee of the four on each cycle. Pneumatics were also used to move our tray up and down, as well as pull our robot onto the first bar of the pyramid at the end of the match for a quick ten points. To make sure Cathy has enough air, she has five Clippard air storage tanks, as well as an on-board compressor to keep compression throughout a match.
New and Interesting:
Ultimate Ascent was one of FIRST’s most strategic games ever! With the difficulty of being able to do every part of the game task, robots had to specialize in different roles that could compliment each other, as well as design strategically early on in the season. Because of our competitive success throughout the season, we were invited to the prestigious Indiana Robotics Invitational for the first time! We had a great experience, and were inspired by the teams and robots we got to compete with and against.
Team 20 at World Championships in St. Louis
Over 8000 matches of officially sanctioned Ultimate Ascent were played.
2014 – Aerial Assist
Robots this year had to pick up and score 2′ diameter exercise balls in the high and low goals on their end of the field. Bonus points on each goal are scored by having multiple robots on a three-team alliance all possess the ball before entering one of the goals, as well as throwing the balls over the mid-field “truss”, and catching the ball after it has been trussed. Unlike 2011-2013 games, the field had no safe zones, and as such, heavy defense made scoring in the large goals not as easy as it may appear to be.
Eclipse has several unique features that make her an exceptional robot in competition, and a great alliance partner. Her features and consistency allowed Team 20 to win both the inaugural New York Tech Valley Regional and the Finger Lakes Regional as the first overall selection. She also made it to the quarterfinals of the Archimedes Division at the World Championships in St. Louis.
Chassis and Drivetrain:
Since Cathy’s 2013 West Coast Drive was such a success, Eclipse was equipped with another iteration of the Rocketeer’s 6-Wheel West Coast Drive. Experience in the off-season taught us valuable lessons about two-speed drivetrains, and the open-field nature of Aerial Assist led to 20’s most powerful drivetrain yet. Eclipse is loaded with a two-speed, 4-CIM 2-MiniCIM drivetrain on Colson wheels. The power and reliability of Eclipse’s drivetrain made her a powerful defensive robot when she’s not busy scoring balls or assisting alliance partners. She can move at 6 ft/s to push others around, or 16 ft/s to traverse the field quickly.
As many teams this year did, Team 20 took inspiration from Team 16, the Baxter Bomb Squad, and their 2008 robot in designing a collection mechanism. Eclipse’s collector is comprised of two pneumatically actuated arms with a rolling axle on the end of it. The green Banebots wheels used on Cathy from 2013 were once again used for collection in 2014. The collection system and the catapult rotate about the same dead axle for packaging and purposes.
Eclipse utilizes a powerful catapult on massive torsion springs custom wound by Jones Spring Company. The catapult is winched back with two CIM motors in a student-designed gearbox that engages a pawl inspired by our 2010 robot. The catapult then has two release modes. One setting is for a high goal or truss score, where both the pawl and the motors disengage to fire the ball to score points, the other setting only releases the pawl, slow-firing the mechanism so it can score in the low goal easily.
To fire the ball where we want to to go, there are a few points where Eclipse can be adjusted in the pits to change the arc of her shot. The “fingers” of the catapult, as well as the cross-webbing between them create different angles of release for the ball. The other adjustable piece is our pre-tensioners. These are located on an axle below the one that contains the catapult and collector. These attach to our springs with hose clamps and create varying amounts of pre-tension on the torsion springs, creating a more or less powerful shot. They also restrain the springs, creating a “soft stop” for the catapult so it doesn’t put too much stress on the strap pulling it back. The packaging between the collector and catapult is very tight and took multiple iterations to get correct.
The catapult is surrounded by three “catcher panels” that expand out on pneumatic pistons to catch a ball thrown over the truss by a partner and to assist in human-loading. They are made of fiberglass rods, fabric, and foam peanuts to help deaden the ball’s impact. To catch, all three catchers close at once like a glove. The two side panels also help to center the ball as it leaves the catapult. Between the Finger Lakes Regional and the World Championship, the back panel was increased in size to improve our catching and inbounding abilities. This change was inspired by watching footage of Team 33, the Killer Bees, Team 1024, the Kil-O-Bytes, and Team 2056, OP Robotics all being able to inbound and catch easily.
New and Interesting:
The game required more cooperation with alliance partners than ever before! Because of the open field, defense was huge, and because of the exponential scoring nature of the game, many different strategies can be employed to win, including heavily defensive ones. Matches in eliminations can range from huge scores to small ones based on how each alliance decides to play the game.
Team 20 in the finals of the Finger Lakes Regional:
2015 – Recycle Rush
Robots this year had to create a stack of totes and place them on the scoring platform, capping them with recycling containers. In addition, litter (in the form of a pool noodle) can be placed inside the top opening of a container, with an addition of six points. Litter can also be thrown from the back of an alliance wall to the opposing alliance’s field. Co-opertition points can be scored by placing yellow totes (also used during autonomous) in the middle of the arena on the white-marked step.
Atlas is an external-stacking robot that led Team 20 to become finalists at the 2nd annual New York Tech Valley Regional and winners of the Carson Division at the 2015 World Championships in St. Louis, MO.
Elevator and Carriage Mechanism:
The Elevator System was made out of an aluminum c-channel frame to allow for the carriage to smoothly traverse up and down. The Carriage System itself contained two aluminum ‘forks’ that moved on a horizontal axis to allow Atlas to pick up and drop totes. The Carriage system moved using a worm gear powered by a MiniCIM motor. The Elevator system itself moved the carriage up and down using a belt system powered by four MiniCIM motors. To help counteract the weight of the carriage and totes two lengths of surgical tubing were installed.
Chassis and Drivetrain:
Because of the shape of the scoring platforms this year, Team 20 decided to create a bent frame that would allow for all four mecanum wheels to be touching the ground while straddling and strafing along the platform. The drivetrain Team 20 used was made up of four mecanum wheels powered by four separate CIM motors that allowed Atlas to traverse at 11ft/s. The motors and gears used to move the wheels were put in a protective 3D-printed housing.
Tote Collection System:
Atlas’ unique tray system is comprised of a pulley system underneath the tray that is made of rope attached to their corresponding motors/encoders. This included a tension control system that worked well for the rope added with a piece of HDPE added into the frame. The tray system allowed for Atlas to ‘catch’ totes from the human player station
New and Interesting:
Recycle Rush was a very different game than the ones of years past. This was due to some of the many game rule changes FIRST made for this game. This year bumpers were optional due to the fact that there was no interaction with the opposing alliance. In fact this year featured a different scoring system which did not feature the traditional win/loss system where each team was ranked based on an average of their qualification match scores. The only time a team could win or lose was during finals matches where the traditional best two out of three system was still in practice.
2016 – Stronghold
The game is played by two alliances of up to three teams each, and involves breaching the opponents’ defenses, known as outer work as well as capturing their tower by first firing “boulders” (small foam balls) at it, and then surrounding or scaling the tower using a singular rung on the tower wall. Points are scored by crossing elements of the tower’s outer works, shooting boulders into the opposing tower’s five goals in order to lower the tower strength, and by surrounding and scaling the tower.
Chassis and Drivetrain:
One of the top priorities for our robot this year was to have a strong drivetrain that would be capable of crossing many of the defenses while being able to traverse the field quickly, push other robots, and resist pushing. To accomplish these objectives, the robot was designed for a six-wheel west coast style drive train with six 8 inch pneumatic wheels.
Boulder Control (Mechanical “Lance”):
Next on the priority list was the ability to manipulate boulders. This is accomplished via a mechanism appropriately nicknamed “the lance”, a roller collector to pull the ball in with inverted ramps to help the front of the robot clear the defenses while driving over them. Our robot is also able to score in the high goal using a hooded flywheel shooter, spinning at 11,000 RPM so as to eliminate the effects of variability between the different boulders.
Defense Crossing Mechanisms:
The final mechanisms on this year’s robot are a set of passive ramps for raising the portcullis, a defense that operates somewhat like a sliding garage door. These mechanisms, nicknamed “the tomahawks” after a similar mechanism used by another team, allow the robot to raise the portcullis simply by driving up to it and pushing with the angled part of the ramp. These “tomahawks” can also be used to cross the “cheval du frise”, which is basically an alternate-facing four bridge contraption. The “tomahawks” would have to be lowered in order to also lower the two upper-facing bridges.
Combined, these features also had to be shorter than 14 inches so that the robot could pass underneath another defense (the low bar), allowing the robot quick access to the side of the field with the opponent’s tower. Packaging these mechanisms into such a small space was quite a design challenge, and gives the robot its distinct look. Due to its resemblance to a scorpion when the lance is lowered and the tomahawks are raised, as well as the team’s general space theme, the robot has been named “Scorpio” after the constellation.
New and Interesting:
This year’s game had a win/loss system, and the ranking system depended on how many ranking points were scored during all of the playoff matches. Ranking points could either be scored by having 4 out of 5 defenses completely damaged, making the defenses breached. Breaching defenses is considered one ranking point, while having all robots scale the opposing tower’s batter at the end of the match is also considered one ranking point. In addition, one robot from each alliance can be placed in the opposing alliance’s side of the field, which the robot is considered a “spy bot”.