Throughout the week we did heavy analysis of the game. We compared scores and developed possible ways to complete tasks. We've determined the most critical way to score is through Buckies, followed by large balls, then eventually hanging.
We started off by completing a vex test. Every member answered questions which covered scoring, rules, and dimensions of the game. Everything necessary to start designing for the game.
Members uninterested in designing worked on cleaning up the shop while others worked on designing. Reflecting on the analysis, we chose that bucky balls was the most important way to score. We came to this conclusion because bucky balls were valued at 50 points, nearly half the possible points earned by a team. So, as a group, we discussed ways to effectively pick up balls. We knew we wanted a method which could quickly pick up balls and score them as fast as possible. Because of this, we chose to test out side rollers like gateway, conveyorbelts like elevation, and scooping systems like elevation.
During this week we also worked on drivetrains. The first drivetrain we wanted to prototype was an elevated drive with 4 mecanum wheels wheels. We plan that if the drivetrain is elevated at least 2 inches so nothing drags, all of our wheels will consistantly touch the ground, conserving power better than other systems. By using mecanum wheels we gain holonomic capabilities which we believe will be useful in navigating through the tight corridors of the game. Though generally the game objects are movable, we believe that there are factors such as the bump, barrier, and robots that will render balls immovable. Currently, we geared the drivetrain to 1:1.25 speed, giving a slight speed bonus.
We also developed a chain bar, geared 5:1 torque on two 393 motors. we ran a test and it was able to lift 3 wide steel C-channels and a linear slide
In addition to the robot, we started fabricating our own field components. We quickly developed a goal using sheet metal, however we ignored the fact the goal is in octagon. Instead we rolled the sheetmetal into a circle with a diameter of 8 inches. We also started developments on the bump and hanging bar. With the hanging bar, we cut a piece of pvc and mounted it on 2 blocks of wood. We then placed it on the sides of 2 tables.
Prototyping came out pretty smooth. We built side rollers with anti slip mat because we didnt have tank tread. We tried out conveyorbelts, and we also decided to add a roller on the scoop to control which balls enter and leave the system.
Side rollers worked well. The scoop system rollers worked well once we geared it for speed. However, the conveyorbelt worked slightly better than the side rollers. It could grab faster and it could roll balls better. We also came up with the idea of using funnels to hold in objects like scoops. Unlike scoops however, funnels theoretically provided multiple strategic options. we could hang with a ball, we can act as a wall bot, and we could defend against a wall bot. However, one of the biggest benefits we believe we'll get is the ability to hoard around balls without actually grabbing them. Because of this ability, the light weight of the side rollers, and the ability to ball lock, we choose side rollers later into the week. Though the funnels would take up motors, we believed it's huge grabbing ability would give us an edge over a faster drive or faster lift, despite past competitions and the success of fast drive trains.
During this week, we also developed a hanging system. Since motors are being optimized towards other systems, we focused on developing a lifting system without motors. We looked towards ultimate ascent, where they created lifting systems which required nothing. We developed a "scyhe" which, in theory, allows us to hang by running into the hanging bar. Though it'll only earn us 5 points, by adding on the large ball, we can score 15. If we could torque up the arm system, we could possibly high hang with a ball. When we tried testing it, the axles we used on the drivetrain collided with the hanging structure. Rather than cutting our axles now, we decided to just remake the hanging bar
Our large ball manipulator was quite simple. We decided to use a forklift which springs out at the start of the match. This springy motion also allows the robot to grab along the wall without issues.
We also continued developing the bump. We have scrap wood hanging around, so we're using that along with our table and miter saw to cut the wood accurately.
Construction started to slow down this week. A lot of our work is running into conflicts or sizing issues.
The side rollers system we developed had issues fitting in dimension. We wanted to avoid a flip out system, but it was unavoidable. We developed a sideways flip out system unlike the standard top down fold out. By doing this, we hope to grab and release balls faster than standard rollers and achieve our original goal of fitting in dimensions.
While we were applying a flip out system for the side rollers, we added an additional motor to the lift system. Theoretically, this motor can allow the robot to lift another 2.5 pounds. With this additional strength, we plan on adding the hanging system and possibly. We tried testing it out today, but it was quite complicated to test cause we used our mecanum drive code as a universal code with all our prototyping.
We ran into issues mounting the large ball manipulator. Because the rollers were so large, the forklift would hit the rollers.
The funnel system was also developed. we used sprockets to act as mounts and 12.5 rails and standoffs to be the actual funnel. We tried chaining the funnels at 6:1 torque, however pillowblocks conflicted with drivetrain pillowblocks forcing us to remount the sprockets somewhere else. While bracing the drivetrain, we decided to use one of the braces as the new holders for sprockets, we're currenty chaining the funnels now.
Since de-scoring has been confirmed to be legal in a practical sense, we started developing a de-scoring system. currently, the de-scoring system is a folding forklift which drops into the columns and pulls out balls as the lift is raised. Due to the barrier, we built the lift to reach 2 buckies. One issue we ran into was rollling friction. As the balls were raised out of the goal, it rubbed against the opposite side of the goal, causing the balls to spin and bypass the forklift. We plan on extending the forks to counteract rolling friction.
Week 1 Analysis (excel)
Week 2 Photos
Week 3 Photos
Week 4 Photos
First Lift Test
No dragons were harmed in the making of this video
Unsuccessful Test: Intake + Deadweight
Strange part about this video, the lift raised all the metal before video was taken. Must have been due to maximum power from the battery, however the robot was still green on the second lift. Chances are, weight like this wouldn't be reliable for competition
Successful lift test: Intake + Deadweight
uses a steel 17.5 inch channel for the arm, three 12.5 inch aluminum channels, and 5 large wheels