We have been hard at work the past few days prototyping mechanisms, mocking up field components, and beginning coding!
Simulating Shooting Angles
For simplicity’s sake, we want to avoid an adjustable hood shooter if possible. In the programming subteam, we started tackling the shooter options in order to be able to shoot into the upper hub by changing the velocity without changing the angle of the shooter. We used MATLAB in order to check the trajectory of the cargo from different key positions in the field. We found that for shooting from all distances up until the launchpad 2 shooter angle positions are optimal. Further explanation can be found at @adamv 's post.
We have two main concepts for climbers:
Stick on a wrist: A long pole with hook on both sides swinging the robot pole to pole, much like in SnowProblem’s RI3D build. We just finished our first medium-scale prototype of this climber, and are starting to test its viability. More to come on this front soon.
Elevator and wrist: An elevator with a hook on top, which raises the robot to the 2nd rung. A hook on a wrist then locks on to the 2nd rung. With the robot fully on the 2nd rung, the elevator rises, disconnecting from the 2nd rung and then, using the wrist to change the angle of the robot, the elevator hooks the 3rd rung and pulls the robot to it. The wrist lets go of the 2nd rung and the robot is now hanging from only the 3rd rung. This mechanism is similar to ZouKeeper’s Ri3D climber Theoretically this concept can climb an infinite amount of rungs, making it very alluring.
For the over the bumper intake we decided to take direct inspiration from 2020 robots and built a general prototype allowing us to easily change the positions of the rollers of the intake. Using the green compliant wheels we managed to get a decent control of the ball, but trying to center it using mecanum hasn’t worked so far.
Videos of the prototype (will be updated over time) are available here.
For the through the bumper intake we took heavy inspiration from 2016 robots, trying to convert a face of the robot to a wide bumper using wheels arranged in a cone shape. While testing has been successful the problem with this concept is the balls bouncing from the wheels instead of being lead by them. To solve this we implemented an over the top roller to force bouncing balls into the wheels, making this concept a merge of the two types. We’re now working on improving the funnel wheels and investigating the possibility of moving the funnel wheels onto the intake to be deployed outside the bumpers.
More videos of the prototype are available here.
We started testing the high-goal shooter using a modifiable prototype with variable compression, wheel type/size, hood angle, # of motors, gear ratio, and flywheel mass. Our goal is to find one or two angles that give us the widest range by only varying flywheel speed. Our initial strategy requirements say that we want to be able to shoot from as close as possible, and up to 5m away.
In testing, we found a good combination of 4" colson wheels, 1x falcon at 1:1 with our 2020 flywheel, and 20mm compression. We first tested the minimum release angle that would allow us to score when touching the HUB; this came out to 69°. We then backed up the target until we got to our max range, which was ~3.5m. This is likely not enough range for our strategy, so in the coming days we’ll test a second hood angle for longer-range shots. Testing a number of hood lengths, we found that the longer hoods keep the ball in contact with the flywheel longer, increasing the max distance. We ended up with a hood arc length of 55° on a 272mm radius.
Videos of the prototype testing are available here.
We wanted to prototype a conveyor system to check the required compression, belt distances, etc. On the first prototype, we forgot that the belts not being centered on the ball means the ball has a smaller effective diameter, reducing the compression. While it does work, it doesn’t hold the ball securely enough for our satisfaction. We don’t want to completely remake the prototype, so we are working on modifying it to allow for larger compression so those numbers will be available when we go to design the real conveyor system. Meanwhile, we have attached the through-the-bumper intake to the conveyor inlet to begin testing system integration.
More videos of the prototypes can be found here.
We were able to create a small prototype of this year’s retro-reflective target, and successfully identify it using the PhotonVision grouping mode and a deconstructed PSEye3 camera.
Additionally, we have been working on automatic detection of cargo position and color. Using OpenCV, we were able to both identify cargo within the image based on color and differentiate it from other objects of similar colors (e.g. bumpers)
We’ll have more updates on prototyping results and strategy decisions coming soon