Intake Geometry & Deployment

The intake is how game pieces get from the field into your robot. Getting the geometry right is the difference between "touch it, own it" (game piece is controlled the instant the intake contacts it) and "nudge it around the field for three seconds hoping it goes in." This page covers how to design the intake's shape, roller placement, and deployment mechanism together, because they're not independent decisions.

The two deployment types

Almost all competitive FRC intakes that pick up from the ground use one of two deployment styles. Both are "over-the-bumper" (OTB) intakes, meaning the game piece gets pulled against and then over the bumper into the robot.

Slapdown (2-bar)

A slapdown intake is a single set of arms with rollers that pivots on one point at the top of the bumper area. When deployed, the arms swing down and forward so the rollers contact the ground in front of the bumper. When retracted, the arms swing back up and the intake stows vertically behind or above the bumper.

How it works: One pivot point, one set of arms, simple arc motion. The rollers swing down in an arc, contact the game piece, and pull it up and over the bumper as the intake retracts.

A motor powered pivoting intake that flips up for a handoff. Source: frcdesign.org

Advantages:

• Mechanically simple (one pivot, one motor or spring)

• Fast deployment (just swings down)

• Easy to prototype and iterate on

• Fine control over intake position since motor angle directly controls roller position

Disadvantages:

• Stows vertically, which takes up height inside the frame

• The arc path means the rollers don't maintain a constant distance from the bumper during deployment, which can cause geometry issues with certain game pieces

• Can be floppy at full extension if the arms are long

Used in: 2019 (cargo), 2020 (power cells), 2022 (cargo), 2023 (cubes), 2024 (notes), 2026 (fuel cells)

FRC examples: 1323's 2022 cargo intake, 4414 HighTide's 2023 cube intake

4-bar linkage

How to choose between them

Factor	Slapdown	4-bar
Design time	Faster to design and iterate	More time in CAD working out linkage geometry
Vertical space	Stows tall (vertical)	Stows shorter (horizontal or angled)
Stiffness at extension	Can be floppy on long arms	Stiffer because two links triangulate
Packaging	Takes vertical space but small footprint	Takes horizontal space but low profile
Prototyping	Easy to prototype with one pivot	Harder to prototype, more pivot points
Best for	Games where vertical space isn't tight and simplicity matters	Games where the robot is space-constrained or the intake needs precise positioning

If you're not sure, start with a slapdown. It's faster to get working and easier to adjust during build season. Move to a 4-bar if the slapdown doesn't package well or you need more precise control over the deployed position.

Designing the layout sketch

Regardless of which deployment type you use, the design process starts the same way in Onshape:

1

Draw the bumper cross-section and game piece

In your layout sketch, draw the bumper (typically 5" tall pool noodle backed by 3/4" plywood, with about 3/4" ground clearance). Then draw the game piece at its starting position on the ground, touching the front of the bumper. This is the geometry you're designing around.

2

Define the game piece path

Draw the game piece at several intermediate positions as it moves from the ground, against the bumper, over the top of the bumper, and into the robot. This path tells you where your rollers need to be at each stage of the intake cycle.

3

Place the rollers

Position rollers so they maintain contact with the game piece throughout its entire path. The rollers need to apply compression (squeeze) on the game piece at every point along the path, including the critical moment when the piece crests the top of the bumper. If there's any point where the rollers lose contact, the game piece will get stuck there.

4

Design the deployment around the rollers

Now work backwards from the roller positions. For a slapdown, find a single pivot point that lets the rollers reach both the deployed position (touching the ground) and the stowed position (inside frame perimeter). For a 4-bar, define the deployed and stowed positions of the intake plate, then solve for link lengths and pivot points that connect the two positions.

The sphere deadzone problem

When the game piece is a ball, there's a geometric trap that doesn't exist with flat or rectangular objects. You might size your roller position so that it can grab a ball sitting on the ground (roller is at the right height) and so it can grab a ball pressed against the bumper (roller is at the right distance from the bumper). Both of those cases work individually. But when the ball is sitting in the corner where the ground meets the bumper, the roller can't reach it, because a sphere doesn't fill corners.

A cube sitting in that corner would touch the ground, the bumper, and your roller simultaneously. A sphere curves away from the corner. Its surface is recessed inward compared to where a box's surface would be, which means there's a gap between the ball and your roller even though the roller is correctly positioned for the "on the ground" and "against the bumper" cases individually. That gap is the deadzone.

The fix: Your leading roller needs to be positioned closer to that corner than the individual cases suggest, or you need to add a separate low ground roller that contacts the ball from below and pulls it out of the corner before the main rollers take over. Either way, draw the actual ball diameter in your layout sketch sitting in the corner (on the ground and against the bumper at the same time) and verify that your roller makes contact. If you only check the two flat cases separately, you'll miss this.

This is purely a geometry problem. Sketch a circle (the ball) tangent to both the ground line and the bumper face in your layout sketch. Then check whether your roller actually touches that circle. If it doesn't, you're in the deadzone.

Compression

Compression is how much the intake squeezes the game piece between the rollers and the bumper (or between two rollers). It's one of the most important dimensions in your layout sketch.

Too little compression: The game piece slips through or gets stuck at the top of the bumper because the rollers aren't gripping it hard enough. This is what happened to 254 in 2017 when they had to redesign their upper roller geometry after balls got stuck at the bumper crest.

Too much compression: The motors stall trying to pull the game piece through, or the game piece deforms and gets jammed. Excessive compression also wears out rollers faster.

How much is right: This depends entirely on the game piece material and your roller material. There's no universal number. The only reliable way to find the right compression is to prototype and test. Start with about 1/2" to 3/4" of compression on the game piece and adjust from there.

Account for bumper compliance. The bumper is made of pool noodles, which compress under load. If your geometry assumes a rigid bumper surface, you'll have less actual compression than you designed for because the bumper squishes inward. Add extra compression to compensate, or test with actual bumpers during prototyping.

Actuation

Method	Pros	Cons
Motor with gearbox	Precise position control, can hold intermediate positions, software-tunable	Heavier, more complex, requires PID or motion profiling for smooth deployment

For most of our intakes, a motor with a MAXPlanetary gearbox is the standard approach. It gives the most flexibility during the season because you can adjust speed, position, and hold force in software.

Hard stops

Every deployable intake needs physical hard stops that limit travel in both the deployed and stowed positions. Without hard stops, the intake can over-rotate and damage itself, tangle with other mechanisms, or go past the frame perimeter.

1. Deployed hard stop: Prevents the intake from swinging too far down. This sets the exact deployed position, which means your roller geometry is consistent every time the intake deploys.

2. Stowed hard stop: Prevents the intake from swinging too far up or back. This keeps the intake within frame perimeter and prevents it from colliding with other mechanisms.

Hard stops should be physical contact rather than relying on the motor to hold position. If the motor loses power or code crashes mid-match, you want the mechanism to be physically constrained.

Past game examples

2026 Rebuilt (fuel cells / spheres)

The fuel cells are inflated spheres, which means the sphere deadzone problem applies. Most competitive intakes this season use either a slapdown or 4-bar with a low leading roller that reaches under the ball. Compression against the bumper is critical because the balls are soft and deformable. Many teams are using compliant rollers (flex wheels or polyurethane) for maximum grip.

2024 Crescendo (notes / flat ring)

Notes were flat, flexible foam rings. Slapdown intakes were extremely common because the game piece was thin and light, and slapdowns deployed fast. Compression requirements were low since the game piece was soft and light. Some teams used ground rollers to sweep notes toward the bumper from a wider capture area.

2023 Charged Up (cubes and cones)

This game had two different game pieces with very different shapes. Cubes were soft and deformable (good for roller intakes), while cones were rigid with a specific orientation. Many teams used wide slapdown intakes for cubes and separate or adjustable mechanisms for cones. The dual game piece challenge made intake geometry particularly important.

2022 Rapid React (cargo / spheres)

Cargo were medium-sized inflated balls. Both slapdown and 4-bar intakes were common. The sphere deadzone was a real issue. 1323's slapdown and 1678's 4-bar are both excellent examples of effective intakes for this game. Compression geometry over the bumper was the main design challenge.