Our robot for 2015 was Scarab, named after an Egyptian dung beetle that completes a very similar task. Scarab’s job was to pick up totes and bins, carry them to a more desirable location and them stack them on top of each other. The higher the stacks, the more points Scarab got, so at 197cm (6ft 6) she was (and remains) the tallest robot we have ever built. Scarab also featured a mecanum drive base for added maneuverability and an array of limit switches used to determine exactly how many totes have been lifted at any given time.
The game for the 2015 FRC competition was Recycle rush. The aim was to build a robot with the ability to stack boxes, a garbage bin on-top of those boxes and then trash (pool noodles) into the garbage bins in the correct area. Points were given depending on the amount of boxes stacked, the amount of trash in the bins, and whether or not the yellow boxes have been stacked. Trash left outside the scoring sections is thought of as “unprocessed litter” which deducts 1 point from the score. Watch the video above for more information on the game!
Our game piece was a right angled triangular prism. It stood about two meters tall, and 80cm wide. The vertical face was covered in clear acrylic, which in turn had three tracks attached. A single track ran down the centre, with another track on each side, 20cm from the central track. In each track were dollies (little runners commonly used in sliding doors).
The each side rails had three “kickers” which were passive self-actuating devices which would support the bottom of a tote when it was picked up. The central rail had four hooks fashioned from C channel. This set up was connected via strapping to a worm driven winch. Along the winch track were two limit switches which stopped the winch at either the top or bottom of the track, so as to prevent jamming.
Out the front of the game piece was our intake system, which comprised of two omniwheels mounted on minicims. These minicims where in turn mounted upon a protruding length of aluminium extrusion, which allowed us greater dexterity with the totes and bin.
- Quite a simple design, which made the constant maintenance easy.
- Locations to mount a camera for real time streaming to driver station.
- Quick and easy to take apart and reassemble.
- Easy to attatch to the drive base (8 screws)
- The kickers would often jam.
- Limit switches would occasionally get caught and jammed into a set state.
- Quite heavy, meaning we could not put in as much ballast at the back of the robot as we would have liked.
- Due to the shape, all totes and bins hung out the front of the robot, which decreased the performance of the mecanum drive base.
At the beginning of the build season, we considered a wide variety of drive bases. We went through a process in which we evaluated how we wanted our robot to operate in tandem with our high level strategy. We decided that we needed a drive base that was able to easily traverse across platforms, as well as one that was able to move around the field with agility so as to avoid stacks, platforms, totes and other robots. We eventually settled on an O-Drive as our chosen drive base.
An O Drive is made of 6 “Omni Wheels”- wheels with small rollers on them that allow them to slide perpendicular to the direction in which they spin. There are 4 wheels at the sides facing forwards, as well as one each at the front and back to provide sideways power. This lets the robot both strafe sideways and move backwards and forwards. Unfortunately, we were not able to use this design due to manufacturing difficulties with bending mounting plates for the front and back wheels. As a result, we ended up using “Mecanum wheels”- wheels very similar to omni wheels but with rollers angles at 45 degrees rather than perpendicular to the wheel. They are also able to strafe sideways by moving the wheels relative to each other. However, our robot was not able to take full advantage of them as mecanumwheel strafing is highly weight sensitive, and with a large game piece as well as totes stacked on the front of the robot, our robot’s ability to strafe was severely diminished.
After a long 6 weeks we had a robot that worked. After countless hours together we were done and ready to compete in Hawaii again and in Sydney’s inaugural regional. The first thing on the agenda after having finished the robot was to show it off to our family, friends and sponsors. After that we got ourselves ready and prepared for our first regional, the Sydney regional. There the new members awed at what was their first competition. Lots of teams, lots of pits and a full game field with an audience watching. After 3 tense days we ended up in the 8th spot, giving ourselves a definite chance at the finals. We ended up in an alliance with the 3rd placed team IC Robotics. Our alliance fought hard and continued to play strong until we made it into the semifinals where our final rank was 3rd as an alliance. We continued with our heads held high into Hawaii, where we were ready to both enjoy the weather and the competition. Once again, we played well, and ended up coming 8th in the finals.
We had finished our two official competitions but prepared for our final competition, DDU the closing event for our season. Held at Barker College we met up with friends from the previous regionals for a more relaxed game of Recycle Rush where we placed 5th before alliance selection, and became an alliance captain. We finished 7th at DDU to finish a good season, which we hope to improve on in 2016.
Looking back we all had many experiences, with members of the team spending lots of time in the pits at competition, our new drive coach (Michael Cirillo) working with the drive team and even in design and building of the robot. What we learnt throughout all of this as a group primarily is time management and how important it is. Other things we learnt were focus on making the robot easy for anyone to drive and forgiving of mistakes from the drive team. We also learnt a lot in both engineering skills in software and mechanical design and creation (such as how to assemble gear boxes or fix up electronics) as well as personal skills (such as leadership, communication and working together). The things we’ve achieved and learnt over the past year have helped the team become closer, as well as more skilled. As a team we are ready to improve and continue throughout the coming years from this year and previous years.