We designed our chassis with modularity and robustness in mind by constructing a large chassis frame. In addition, we wanted to be agile on the field by having a low center-of-gravity and the ability to swiftly drive between the cages in the barge zone.
Frame
28”x28” square chassis
2”x2” chassis rail with ½” hole pattern to provide greater strength and modularity
Swerve drive with Kraken motors
Bumper
High rigidity with reinforced bumper corners
Easy mounting with WCP cone bumper mounts
Electrical
Bottom-mounted electrical to protect wires from coral
Fully wrapped wires with wire sheathing to prevent damage
Access holes grommeted to prevent wires getting cut
Battery mounted below the chassis rails to keep the center-of-gravity low
Battery mounted on the robot's underside in a foam enclosure to prevent damages
We chose to go with an omnidirectional swerve drive this year, given that this game relies on making as many cycles as possible and avoiding other robots.
Robot Optimization:
The four independent modules take up little volume, allowing for the optimum design of other subsystem mechanisms
The simplicity of this COTS module and the ease of building the rest of the chassis allows the team to focus more time and effort on other robot subsystems
Module Information:
WCP swerve modules
Swerve X2t modules
2 Kraken X60 motor per module
Omnidirectional driving
Motors and Sensors:
Azimuth rotation controlled by a Kraken X60
Drive wheel controlled by a Kraken X60
Wheel orientation measured by a CANcoder
Prototyping:
Rapid prototyping to test the optimal pivot point to ground distance, and the orientation of the cage in the robot
Scoring:
Deep climb
One-way latch mechanism secures robot to cage
Pivot Gearbox:
Powered by 2 Kraken X60’s
145.36:1 gear ratio
Pivot point is located 11” off the chassis
Latch Mechanism:
Two rollers powered by a
single Kraken X44
2 compliant rollers to provide correct cage alignment
Design Constraints:
Can lift 150lbs of weight
Wanted to take up as little space in the robot as possible
Universal mounting to the chassis and latch mechanism
Wanted the gearbox as low to the chassis as possible
We designed a mechanism that picks up coral from the coral station and efficiently transfers the game piece to the scoring mechanism. Additionally, to account for inconsistencies in the human player handoff, we created a large acquisition area and a steep ramp angle.
Coral Intake Components:
30”x20” funnel opening
Large funnel opening allows for inconsistencies in coral handoff from human player
35-degree ramp for fast transfer
Ramp angle matches angle of the coral station
Steep angle of the ramp allows us to instantly drive away without coral falling out
Our 3-stage cascade elevator simultaneously extends each stage in equal amounts, allowing our robot to score coral in level 4 and algae in the net. Moreover, our elevator’s unique design removes the need for a scoring mechanism pivot, reducing the number of potential points of failure.
Cascade Elevator:
3 stages including carriage
Each stage goes up approximately 28”
All the stages move up simultaneously, allowing for more constant and consistent motion than a continuous elevator
Electrical:
CANcoder mounted on gearbox to determine rotational position and velocity
12ft cable bundle with Power and CAN wires wrapped around inside stage tubes
Elevator Components:
Our constant force spring removes 5.94lb off the carriage, offsetting the scoring mechanism’s weight
Constant force spring reduces strain on the gearbox and allows for faster movement
1/8" diameter Dyneema Rope for elevator stringing, lifts up a maximum capacity of 450lbs
Tie Rods stabilize the elevator, preventing it from wobbling while extended
Custom Nylon-Printed Tensioning and Rope Tying Blocks, allowing for better stringing and movement
Added ratcheting tensioners to avoid points of failure and difficulty resulting from tensioning Dyneema
Requirements:
Score coral at all levels
Pick up algae from the reef
Score algae in the barge and the processor
Account for human player coral loading inconsistencies
1 motor to keep mechanism light-weight
Elevator Connection:
Moves by elevator retraction
Modular mounting and design allows for scoring for easier repairability and faster iteration
2x2 tube for rigid connection
Coral:
Coral held against a circular surface allowing for a rigid grip
42-degree angle coral outtake, allowing us to score on all levels without a pivot
CANrange to identify coral positioning in mechanism
Passive Algae Flipper:
Passive deployment when the elevator extends
Algae Flipper allows for easy de-scoring and scoring on all levels
Current sensing to keep track of algae in mechanism