Sept 2019 - Mar 2020
Our robot this year is built around two main components; The intake and the lift. We use a compliant wheel intake system on the front of the robot. This allows for the blocks to be picked up from multiple angles. The lift system picks up the blocks and stacks them on our tower. You can read more about the specifics of each component below.
The first thing we designed for this years robot was the chassis. We planned on making a sturdy chassis that we could use for multiple years out of Delrin, however we decided to wait until the next season due to time constraints. Our current robot chassis took the same H design as the proposed Delrin chassis, except it was made out of the stock tetrix parts. We chose this H design as it allowed for mechanisms to touch the floor on both the front and the back of the robot, with a strong support structure in the middle.
The structure of the chassis was fairly simple, but the wheels gave us some issues. We decided on using the new REV mecanum wheels for their quality and maneuverability. These have worked very well for us, but we had some issues attaching them to Tetrix parts. We fixed this by enlarging the pre-drilled holes and attached them to the inside of the frame to save space. We drove the wheels with a chain drive from the motors, as this allowed us to place the motors wherever was convenient.
This mechanism is the start of everything on this years robot. It takes in the skystone from the front of the robot, lifts it up, and moves it into the robot for the claw to pick up. It is able to take a skystone from almost any orientation and move it into a single set position in the robot. The flexibility in the skystone positioning in our intake is extremely important as it will allow us to cut down a great deal of time picking up skystones. As well as this, placing the skystones in a fixed point in the robot allows out claw to be precise and efficient, something we need in this challenge.
When we started thinking of a design for our robot, we had to think of how we were going to grab and stack the skystones. We decided we were going to use a two part intake and output system, as we found immense difficulties with a single part system on our robot in the Rover Ruckus and Relic Recovery games. We saw tremendous success in a two part system from the champions of both those seasons.
After deciding this, we almost immediately went to a set of wheels as our intake for the skystones, seeing the advantages they held in in games like Relic Recovery. We went through many designs for this system, starting with a lightweight flat design with the motor directly attached to the intake wheels, to a slanted design with multiple wheels connected to the motor with chain. We designed all of these systems in Fusion 360 and went through many iterations before ever putting the parts together. By using CAD, we were able to fully build out parts, see flaws and change things without having to rebuild physical structures in the very limited club time we had.
We struggled with keeping this mechanism in the bounds of the 18” cube, but our final design fits and is one of the most reliable systems on our robot.
This year we struggled with the design of our claw the most. The design of it was reliant on the design of other systems, and we had a very limited space for it to fit in. We wanted the claw to be able to reliably pick up and rotate the skystone from the top, having it strong enough to withstand shaking and fast motion. We had almost all of our design team working on this and we eventually came up with three main designs we decided to fabricate and test for the characteristics we mentioned before.
The first design expanded in the middle of the two stubs on the skystones, creating enough pressure to lift it off of the ground. The second design for the grabber was the opposite, using pressure to squeeze one of the stubs on the skystones. The third and final design had a supporting plate on the back side of the skystone, brackets on each side of the stub, and a bar that compressed the skystone to the back plate using the stub. After testing, we decided to use the third design, as it performed the best. After deciding this, we added silicone rubber to the plate to make it have even more gripping power.
The Lifting Mechanism on our robot is one of the most improved systems from previous years. In the past, we have only ever used rack and pinions or extrusion based linear slides. While both systems worked well, they had disadvantages that would have made them difficult to use on this years robot such as using too many motors or being too unreliable and fragile. Due to these factors we knew we wanted to improve our linear motion even before the season started.
In the offseason we started to look at how other teams tackled this problem. In our research we discovered that draw slides were something many teams used for their robustness and smooth action. After finding this, members spent time developing a system that could be used for any task. Once the season started, we just modified the system for the specific job it needed to do and had great success with it.