2019-2020

SKYSTONE

During the Sky Stone season, our team sought to build a robust, advanced, and fast robot. We experimented with several different mechanical designs including scissor lifts, linear slides, intake wheels, etc. Through custom 3D printed design components, and a custom built chassis, we built a lighter robot that was more idealized for each task. With our robot, we could build a 6 stone tall tower, move the foundation, park, and quickly intake and deliver stones within the 2 minute time frame of the match, and we were able to compete in the finals and earn awards at every tournament!

Engineering notebook: Engineering Design

Code Repository : FTC2019-Skystone.git

Sky Stone Challenge

In the Sky Stone Challenge, teams race to build the tallest skyscraper. Teams must collect stones from the quarry , deliver them across their alliance bridge, and stack them on to their foundation to earn points for their alliance.

See the Skystone Introduction Video here

For detailed information about the Skystone Challenge, see the Game Manual

Autonomous Period

Deliver Stone from Quarry to Building Side - 2pt / stone
Deliver Skystone (stone with image) from Quarry to Building Side - 10 pt / stone
Place Stone on Foundation - 4pt / stone
Reposition Foundation to Building Site - 5 pt
Robot Parks under Alliance Bridge - 5 pt

Driver-Controlled Period

Deliver Stone across Alliance Bridge from Quarry to Building Side - 1 pt / stone
Place Stone on Foundation - 1 pt / stone
Skyscraper Bonus - 2 pt/ skyscraper level

Endgame

Capstone (custom made by team) placed on Foundation - 5 pt + 1 pt/level of stones supporting capstone
Move Foundation out of Building Site - 15 pt
Robot Parks in Building Site - 5 pt

Season Awards

Innovate Award

Deep South League

Finalist Alliance

Deep South League

Think Award

Jersey Shore

Finalist Alliance

Jersey Shore

Think Award

Southern Scuffle Qualifier

Evolution of the Chassis Assembly

The “Chassis Assembly” refers to the base of the robot, including the wheels and main frame. The chassis assembly is extremely important because it affects the speed and movement of the robot, and also provides a base which any design ideas must be compatible with.

Design 1

Original Chassis

Expansion Hubs Placed Flat next to each other and centralized in the robot
Dimensions: 17.5’’ x 17’’
Gear Ratio: 1:1
REV Hex Motors - 40:1 Spur gear box
Extrusions used as support beams
Modelled after the AndyMark Mecanum TileRunner Chassis

Design 2

Chain and Sprocket

Gear Ratio: 2:1
Dimensions: 16.5’’ x 13’’
REV Hex Motors - 40:1 Spur gear box
Used a chain and sprocket system
Motors were moved towards center

Design 3 (Final)

AndyMark Motor Chassis

Gear Ratio: 1:1
Dimensions: 16.5’’ x 13’’
NeveRest Orbital 20 Gear Motors with 20:1 planetary gearbox
Motors completely centralized
Uses chain and sprocket system

Evolution of the Intake Assembly

The “Intake Assembly” refers to the system/method in which the robot picks up the stones from the field. Whether it be through the use of a gripper or through intake wheels, we want the intake system to be very fast and efficient so that we can deliver and score stones quickly and efficiently as possible instead of chasing stones around the field.

Design 1

Original Linear Gripper with Linkage

“Lifter” which brings gripper down to pick up stones at ground level
Horizontal linear extension to extend gripper outwards when grabbing stones and retracts the gripper into the robot to fit within 18x18x18
“Linkage system” to clamp the stones
3D printed gripper parts lined with the insides of ping pong paddle rubber.

Design 2

Foam Intake Wheels

4 black foam intake wheels used to grip the block from the top with two intake wheels power, two not powered
Spring Mechanism that presses intake wheels together while allowing flexibility to expand when stone is intaked
String used as a limit to open wheels to proper size
“Lifter” to bring the intake wheels down onto the stone to intake them
Shortened the horizontal linear slide system to fit under 14’’
Horizontal linear slide system to retract the gripper into the robot (to fit within 18x18x18) and extend the gripper outward (to intake stones)

Design 3 (Final)

Rubber Intake Wheels

Uses three Andy Mark 4 inch compliant wheels
One idle unpowered foam wheel
Left wheels powered by belt, while right wheel only powered in front
Front wheels are powered directly by the motor and back wheels are powered by belt

Evolution of the Placement Assembly

The “Placement Assembly” refers to the system/method of stacking a tower. This includes any linear lift system to bring the stone to a desired height, and the gripper which holds the stone before stacking it on the tower. For our earlier designs, the gripper which released the stone was the same as the gripper that intaked the stone, so there was no need for a separate assembly for dropping the stone. When we switched to intake wheels, however, we needed a separate gripper for placing and stacking the stones.

Design 1

Scissor Lift with Metal Plates

Used four sets of scissor lifts, two per side made of aluminum plates
Motor system uses a linear actuator to push scissor lift upwards
Mounted to a x rail slide to move the side of the scissor lift inwards
Only one side of the scissor lift moves inwards while the other rotates on an axle
Actuators cut to size using ServoCity linear Actuator

Design 2

3D Printed Scissor Lift

Was 3D printed to the same dimensions as the aluminum scissor lift
3D print was made in two halves and glued together to create 11 inch pieces
Axles were also 3D printed and a screw was fit within to give support to the 3D axle
Also used linear actuator to power the system

Design 3 (Final)

Linear Slides with Various Servos

Linear slides to stack upwards
Extender that uses multiple servos
Slapper to push the block into the correct place.
Back plate with bottom lip to provide support for the block
Corner on back plate to keep block in correct place
Servo with gripper mounted above nub
Plate to grip nub

Autonomous Path

Move forward to drive up to the stone. Turn on the intake wheels, and move forward slowly into the stone to intake it
Move backwards to be just in front on the main bridge (we don’t move too far beack so that if our alliance partner is parking along the wall we won’t crash into them)
Turn so that the placement assembly faces the bridge (90 degrees with the IMU gyro)
Drive under the bridge and toward the foundation to deliver the stone
Turn so that the placement assembly faces the foundation (this is 180 degrees with the IMU gyro), then release the stone, to score it on the foundation.

6. Move backwards, and close the placement assembly (so that it is no longer sticking out of the robot)

7. Move forward again to be right up against the foundation and hook onto the foundation

8. Turn the foundation to the left about 45 degrees

9. Move the robot back a little bit

10. Turn the foundation another 45 degrees so that it is now parallel with the wall. Bring the hooks up and straighten the robot using the gyro (90 degrees with the IMU gyro).

11. Push the foundation forward into the building site and extend the tape measure to park under the bridge

Videos

Skystone Robot in action

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