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Design Philosophy - Compact and Stable
Design Philosophy - Compact and Stable
The mechanical design involve five parts:
Chassis: Layers of the robot, Sensor mounting, Storage tube, Handle, Control console
Drivetrain: Motor bracket, Wheel and Coupler
Sweeper: Sweeping ACORNs into the robot
Lifter and Valve: Lifting and holding the ACORNs
Shooting Mechanism: Cam and spring-loaded shooting mechanism
All parts were made either using 3D printing (PLA) or Laser Cutting (Duron). By keeping the materials and processes consistent, it is easier to track the tolerance of each method.
Front View
Front View
Side View
Side View
Back View
Back View
Front View
Front View
Side View
Side View
Back View
Back View
Chassis
The chassis consists of three layers and the centor tower. Each layers has its own purpose:
Base layer: sweeper, lifter/valve, shooting mechanism, and the drivetrain
Middle layer: power distribution boards, PICs, motor driver board, batteries, and power bank
Top layer: handles, switch Console, indication lights, and yard indication
Center tower: storage for the ACORNs, signal conditioning board, and the phototransistor
Phototransistor (adjustable angle)
Console
Yard Indication
Cap for the center tower
Layout of the base chassis
Drivetrain
We adapt two-wheel-drive for our robot, with two active wheels driven by the motors provided. Two bullseye wheels are used to balance the robot. To accommondate the storing and shooting motions of the ACORNs, the drivetrain is installed on the rear part of the robot. Since the rotation center of the robot is at the midpoint of the wheel axis, the strategy for tape following and turning is different the center-driving one, which will be addressed in our software strategy.
Right wheel (Encoder - Motor - Shaft Coupler - Bearing - Wheel - Bearing)
Layout of the two motors and wheels
Sweeper
The Sweeper Module employs a servo motor to gather ACRONs and reposition them for ejection and storage. This component ensures the precise placement of ACRONs for subsequent processing steps.
The extended part of the sweeper when closed is used to keep the ACORNs in the tree from falling. If a ACORN fell when the sweeper is closed, the sweeper will hit the ACORN when opening.
Open Position
Closed Position
Lifter and Valve
The Lift Module is designed to elevate ACRONs into a designated storage tube, utilizing a combination of a rack and pinion system for efficient lifting
Featuring a servo motor and a shutter mechanism, the Valve Module is crucial in preventing ACRONs from inadvertently dropping out of storage. When it's time to release the ACRONs, the servo motor actuates the shutter, allowing the ACRONs to descend into the ejection area.
Valve (Right opened; Left closed)
Resting Position (The grey part is the lifter)
Lifted Position (The grey part is the lifter)
Shooting Mechanism
The shooting mechanism is a cam and follower system. This design enables the motor to retract the striker via the cam's rotation until it reaches the sudden change in radius, at which point springs take over, pulling the striker swiftly.
We had three iternation on the shooting mechanism. The first version utilize the rack and pinion mechanism, the partial teeth on the pinion. This design has smaller size but the often skip teeth when turning. We then changed to the cam and follower system, which solved the problem. The third and the current iteration adapts a stronger, more durable motor and a more integrated design to mount the motor and the cam.
Striker (the enter metal D shaft)
Shooting mechanism when the spring is loaded
The sensor senses when the striker is fully pulled back
Demo Videos
The collecting and storing process follows this order:
Sweeper sweeps the ACORN into the robot and onto the lifter.
Valve opens for storing.
Lifter lifts the ACORN(s) and store them into the center tower.
Vlave closed to hold the ACORN(s)
Lifter and sweeper return to its resting position.
Robot Dimensions
CAD File
https://drive.google.com/file/d/1KIn8T-faD8cPZCwBP8Y5lqzYHIcwhhZ-/view?usp=sharing
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