Introduction
This was my teams second competition robot for the V5RC Push Back challenge. We started this season with a hopper-style configuration, but after a few competitions, we quickly realized that our initial design was far too inefficient to keep up with the fast-paced strategies teams started exhibiting. Our first basket-style robot. We utilized a three stage intake system with
Hardware
As such, we started a new robot design, with the central concept of being able to fit underneath the long goals on each side of the field in order to have enhanced maneuverability. The core of this functionality, actuated two bar design that squats down to the height of the center goal, giving us enough clearance to scoot under the bar.
Once we decided on this lift design, we were able to design the intake around it. We used a decision matrix to evaluate between many different intake and lift designs. The obvious solution would be to use some elastics to hold the lift upwards. However the bands had no clear mounting point, which meant it was impractical to build. After much brainstorming, we came up with an innovative design, a polycarbonate compliant “spring” that pushed our intake up, with two 75mm pneumatic pistons pulling the lift downwards. This fit in the material constraints of the game, giving us a minimal footprint way to keep our air usage down when maneuvering around the field.
We utilized CAD software to fully design this robot to iterate rapidly, run stress simulations and design custom polycarbonate to strengthen our robot. Next, I used CAM software to laser cut the pieces out, which we then installed to our robot. We primarily built the robot out of 0.500” x 1.000” x 0.500” C-Channel Aluminum extrusion, with .250” x .375” L-Channel Aluminum extrusion on the lift to minimize weight.
Chassis:
Our chassis was designed to maximize strength, agility, and speed. We achieved this by initially designing our robot around field obstacles. The rear of our chassis was bidirectionally funneled through a 1/16” polycarbonate drive cap, which was custom laser cut to ±.001”, which minimized drive friction. We used six 11 watt motors with a 600rpm planetary gearbox, which was further geared down on a 4:3 reduction to achieve 450 rpm on our six drive wheels. CAD allowed us to fully map out our drivetrain layout, cutting down on production time and ensuring compatibility with future subsystems.
Combined Lift and Intake
This subsystem is a bit of a unique beast. To keep the weight of the 2 bar linkage down and to ensure proper geometry of the lift, the entirety of the intake structure is made of custom polycarbonate. In CAD, we used 2D geometry sketches to sketch an optimal path of the balls, which we then used to calculate the optimal angle for the intake ramp and sprockets. We then used motion study tools in Inventor to find the optimal placement of the pneumatic pistons. Each of the plastic pieces were made in Inventor with the use of the Sheet Metal tools, enabling complex bent geometries in CAD. It further maintained the internal stresses of the plastic, which came in handy when utilizing FEA stress modelling to ensure the strength of each part.
Software
The software for this robot