ROBOT DESIGN
Creatively Designed Robot
Team #1799 Wired-Up!
Hermes’ Crate
FRC 2023 Charged Up
Distinctly Original
Hermes’ Crate (affectionately called Milk Man by team members) is not the largest, flashiest, or most attention-grabbing robot, but its distinctly different design and abilities should earn a spot on an alliance for the elimination matches. Team 1799 developed its own strategy for this year’s game and then did our research to see what other teams were doing. We took advice and design ideas from others but created a design like nothing that was out there. One of our mentors suggested making a narrow (18” wide) robot and we ran with the idea. Within the first week the students modified an old FRC robot, test drove the narrow chassis design, and were convinced it could work. So, we put in the effort to design every mechanism, including our Cube intake and Crate Dumper, around these constraints.
Strategy
The creativity of our robot design comes from the strategy our team developed for this year’s competition. Our team strategy was developed in the first week of build season. Our overall goal is being selected to be on a winning alliance in the finals. We identified the hardest job this year to be placing pieces in the top row of the Grid. Knowing we can’t out-maneuver a swerve drive or out-finesse the amazing arms that some teams are sure to perfect, our strategy was to develop an optimal Support Robot for this year’s game. This meant we could keep our design simple, choosing to ignore the higher rows of the Grid, while mitigating risk for ourselves and our alliance robots. To achieve this we decided we needed to make a robot that would balance on the Charging Station with two other robots (Charging Station 30 pts). A winning alliance doesn’t need three robots that can reach the top row, but they do need three robots that can balance together on the Charging Station. We also need to be able to balance autonomously (Auto 18 pts). We could retrieve and place game pieces in the bottom row of the grid to form those 3 links, but we think we will be more helpful to our alliance score by delivering as many Cube and Cones to the neighborhood for our partner(s) to place (9+ runs likely). If one alliance member doesn’t have to retrieve pieces, the Substation will be less crowded and the middle of the field will be less congested. In addition to being more efficient, this will also help protect our partners from being damaged in a mid-field collision.
Robot Design
Hermes’ Crate has many design features that will optimize our ability to support winning alliances. The common attributes of these design elements are simplicity, reliability and dependability. From the use of standard FRC systems (Kit-of-Parts chassis) or easily obtainable parts (i.e. Crate), and straight forward mechanisms (i.e. only 4 powered movements) design simplicity is maintained. FRC pneumatic systems are tried and tested making it a low risk choice to power our small/light mechanisms. The overall small size of the robot adds a challenge of arranging electronics and keeping them accessible, but our solid upper supports created protected space above the chassis to meet that need. All status lights are visible even when fully enclosed and protected before and during a match. Because we don’t stress ourselves trying to do the hardest tasks, our simple mechanisms can repeatedly and dependably score points every match.
Charging Station
Balancing on the Charging Station is our most important behavior. With it we can provide 22 points each match and get our alliance more than halfway to a ranking point. Balancing ourselves is enhanced with our choice to upgrade to 6 NEO motors and Spark Max motor controllers for our standard Kit of Parts chassis. They provide the strength to get us up and the control to hold our position on the Charging Station. Our extremely narrow robot, made possible by the small size of NEO brushless motors, provides maximum space on the Charging Station for our two alliance members to join us. To avoid tipping over, we have kept our center of gravity low and pushed all 6 wheels to the edge of the robot by moving all pulleys towards the center. The NEOs’ direct feedback to motor controllers made it easy to program precise movement, current limiting, and motor braking.
Crate Dumper
Delivering Cones and Cubes is our second scoring behavior. We identify that traversing the middle of the field (required to obtain game pieces) was the most risky behavior, one that top performing robots would want to avoid. Our robot’s speed and compact size will make it easier to avoid danger. The crate on the top of the robot is at the right height to receive Cones and Cubes from the Single Sub Station. Alignment is simplified by driving along the edge for the field and receiving the game pieces from the side. A sidewards facing camera allows the driver to quickly stop in the correct spot. Side pick-up also removes the need for turning because the robot simply drives backwards across the field. The backwards dumping crate quickly lines up with a lower grid, scoring the game piece and immediately beginning the next cycle. The crate design is a strong and light structure, easily obtained and replaced if damaged. The one small cylinder actuates it with a simple 100 degree rotary motion, and its position when not dumping is maintained by the piston. When traversing the field, it is protected by being fully within our frame perimeter. The double actuating solenoid ensures the crate stays in the desired position regardless of acceleration, braking, or impacts.
Cube Intake
Our second mechanism provides extra capability to take advantage of opportunities to score. The rollers on our intake were inspired by the 2023 EveryBot intake. However, unlike Cones, a Cube does not require a specific orientation to be picked up. Thus, we only needed two rollers, powered by symmetrical NEO 550 motors with PlanetaryMax gearboxes, to grab Cubes from the floor.
More than half of the Grid can be filled with Cubes, so this capability provides more reward for our effort. The Intake System is retracted within our robot perimeter to start the match and anytime it is not in use or traversing the middle of the field. It can be used to pick up and score a Cube from the floor during Autonomous, if an alliance member prefers to be the one to balance on the Charging Station. When delivering game pieces in TeleOp, we can quickly pick up a Cube left on the floor by our alliance or dropped by our opponents. The two pistons provide double the force for raising the Intake arm while keeping their diameters small enough to stay within our frame perimeter. Lowering the arm requires less force, so we don’t waste our limited amount of compressed air. Springs push the arm past its tipping point so that gravity lowers the arm when we simply release the air pressure in the cylinder.
Design Tools
CAD modeling and rapid prototyping of many design features allowed us to assemble and test several design changes before CNC milling our final custom parts (Side plates, Intake Plates, Intake Arms, Electrical Board, Electronics Board, Battery/Pneumatics Plate, Top Cover, Breaker/Switch Plate). Many parts were fabricated from drawings made from the CAD model of the robot(Piston Brackets, Cylinder Brackets, Internal L-Brackets, Bottom plates). Smaller custom parts were modeled in CAD, 3D-printed, tested, and revised (Axle spacers, Crate Support, Solenoid supports, Anderson connector support, Nut capture blocks, Release valve mount). These fabrication processes made it easy for us to make replacement parts, in case something breaks on the field. The design process for creating this robot incorporated many different aspects of modern engineering design and manufacturing, making this an even more valuable experience for the student team members.
