Day #1 Recap
What We Did Today
- Prototyping
- Vision
- Final robot mechanism decision
We spent today prototyping and preparing for the start of our robot build tomorrow. Outside of experimentation, the goal today was to learn enough information (dimensions, motor speeds, etc.) to build the final versions of the mechanisms we decide to include on the robot. The CAD crew will be working hard overnight designing the V1 robot. Everything is summarized in the Day #1 Recap video.
Prototype Updates
#1: Shallow Climber
We have no major updates for this prototype.
#2: Passive Verticalization of Coral (PVC)
An entirely new PVC with one wheel has been created in the last 12 hours or so. It is a one wheel design so we can have one motor and one wheel reducing energy input and weight. It has a polycarbonate funnel on one side to help corral coral into the correct position. The center of the wheel is positioned 6.25” from the polycarbonate support with the bottom of the wheel contacting the center of the coral. The tipping bar is 4.75” from the back plate. This design does a great job of keeping the coral in when it is driving around and a great job of discharging the coral onto the reef. The collection is the main issue facing this part, but we believe with further improvements and a more tapered funnel we can get a design that can retrieve coral from the station extremely efficiently.
#3: Algae Intake
We were able to successfully collaborate with the PVC mechanism (prototype #2) to simultaneously score a coral while removing an algae. Some final dimensions we set on were 36.5” to the height of wheels from the ground, 2” from the center of wheels to edge of the frame, and the same compression and wheels as before. We were able to switch to lighter Neo 550s and see similar success. One of our goals was to have the algae intake as low as possible to give room for the coral mechanism to work. We were still messing with how close we could have the wheels to our robot to make it easier to keep within frame perimeter for our final bot but settled on 2”.
#4: Algae Launcher
We have no major updates for this prototype.
#5: V Coral Intake
The original V-shaped mechanism could intake a coral at any orientation on the field but was unreliable in straightening it out internally. To resolve this, we used a large, spaced out compliant top roller and the solid compliant bottom roller, which work really well for picking up coral at all orientations. The intake rollers are spaced out 6” center to center, with 4” compliant wheels with 3” of space between them on the top, and 2” compliant wheels on the bottom. The coral now moves to one side of the robot with compliant wheels mounted vertically, orthogonal to the top intake roller. This allows the coral to pass through the intake at any orientation, as the intake can force the coral past the indexing wheels, but also allows the indexing wheels to grip the coral once it is inside. The indexing wheels then push the coral against a large idler wheel which causes the coral to align to the same direction regardless of input orientation. If the coral entered the intake normal to the intake plane, (“vertical”), then it would hit the wheel and be knocked down; if the coral entered with its cylindrical axis parallel to the intake wheels (“horizontal”, “lengthwise”) it would go under the idler wheel. Now that the coral is guaranteed to be parallel to the intake wheels, the coral hits another compliant wheel to force it vertically to be handed off to another major mechanism. In isolation, these systems worked. However, when put together, the coral could get caught in the transit wheels. We tried to raise the wheels to avoid this, but then the transit wheels weren’t making good contact with the coral once it was taken in. I believe replacing the transit wheels with a belt system would have solved many of these issues, something like a surgical tube belt or polychord.
#6: Donut Climb
Low climb is hard! Hanging a robot off the side of the lower cage, will cause a large tipping angle, so the robot has to climb quite high on the cage. Because of this, the donut climb prototype attempts to balance the robot around the center of mass and cut out a hole in the belly-pan of our robot and push the cage through that hole to lift up our robot around it. In the video, we only lift our robot up (~1” clearance) because we have not cut a hole in the belly-pan of our robot, with the cutout we should achieve (~3-4” clearance). If the robot is balanced, this should provide the needed clearance. To lift the robot up, we’re using two cams to push down on the top face of the bottom of the cage with a 255:1 geared down NEO motor. Thanks to our swerve drive base, we found that we could effectively drive sideways through the cage and it would come up over our bumper and swing into our corner funnel to capture the cage in a consistent location.
#7: Dual Motion Intake
After testing and making small changes throughout the day our prototype can intake coral off the ground and place it on the reef. In addition, it can intake algae from the reef and carry it to the processor. The biggest change we made was adding 3” wheels 3.75” above the 4” wheels. This is what holds onto the algae when it is taken from the reef. We also created a way to attach the prototype to the elevator mechanism and ensured the angle of the intake will go over the bumper and stay within the frame perimeter.
#8: Handoff
The coral hand-off machine was 13 inches in width and 18 inches in length. We started by having 3 sets of two black compliant wheels so the coral could be transported up from the intake but we quickly figured out that the coral would get stuck on the bottom set of wheels due to the steep angle. We adjusted all the wheels so they were all offset making a gentle angle and creating a smooth path for the coral to go up. We then attached side panels and a back panel so the coral was forced into the wheels and could not be wedged left or right outside the prototype. The wheels were then changed to green-compliant wheels to create a better hold on the coral by compressing it with the back panel. There was one motor used for the whole belt system, having three belts for the three axles the offset wheels sat on.
#9: One Wheel Climb
Unfortunately, this climbing mechanism was very not well documented but is described in our day #1 recap video. The general idea is capturing the deep cage in a similar way to the donut climb, then pivoting in a roller in between the bars of the cage. Lastly, the robot would torque the deep cage and using the friction against the one powered wheel, climb its way up the deep cage. Once the torque was induced, the robot was able to climb up, however we had to hang on one side of the cage to create that torque initially, then once the robot was off the ground, its weight created the required torque and we could let go.
Final Robot Decision
After our evening team discussion, we decided to combine the “PVC”, Algae intake and Donut climb (prototypes #2, #3, and #6) into our final Ri3D robot. We plan on picking up coral only from the coral stations and algae only from the reef in order to try and achieve a deep cage hang, which we think is the most challenging aspect of Reefscape. More details on our decision can be found in our day #1 recap video!
We will post our CAD files as soon as they are ready.
finished the barge, coral station, processor and reef today so they will be ready for prototype testing tomorrow!
