Intakes
An intake acquires a game piece from the field and is one of the most common mechanisms because nearly every game has something to pick up. Typical designs use rollers (compliant wheels, polyurethane rollers, or surgical-tubing/star rollers) spun by a motor to grab and pull the piece in. Variants:
- Roller intake — one or two rollers compress and draw the piece in.
- Over-the-bumper intake — reaches outside the frame and pulls pieces over the bumper.
- Claw/gripper — for rigid pieces that need a firm grasp.
Shooters / launchers
A shooter scores game pieces from a distance. Most use one or two flywheels: spinning wheels that fling the piece on contact. Key design factors are wheel speed (rpm), wheel mass/inertia (to maintain speed during the shot), compression on the piece, and hood angle for trajectory. Two-wheel shooters can add backspin for stability. AndyMark and others sell COTS launcher assemblies.
Elevators
An elevator raises a carriage vertically along rails, usually on bearings/rollers in extrusion. Two rigging styles:
- Cascade — stages extend together so the top moves faster than any single stage, maximizing speed for a given motor.
- Continuous (rigid/telescoping) — stages extend in sequence; often simpler to rig.
Elevators are driven by belt, chain, or rope/cable and require precise control, so prototype motor, ratio, and speed carefully.
Arms
An arm rotates a payload around a pivot. Single-jointed arms are simplest; double-jointed arms reach more positions but are far harder to control. Arms need enough torque to hold against gravity (often a high reduction, sometimes with a gas spring or constant-force spring to counterbalance) and an absolute encoder to know their angle at power-up.
Climbers
Many games end with a climb in the endgame — robots have climbed ropes, bars, chains, and platforms. Common approaches: a winch pulling the robot up on a rope/strap, a telescoping/elevator-style lift hooking a bar, or a hook-on-arm. Climbers carry the full robot weight, so they need high reduction, a ratchet or brake to hold position without power, and robust hooks.
Picking mechanisms
Read the game manual, list every scoring action, and design the simplest mechanism that does each reliably. A robot that does two things flawlessly beats one that does five things poorly.
Key takeaways
- Intakes (rollers), shooters (flywheels), elevators (cascade vs. continuous), arms (pivot + counterbalance), and climbers (winch/lift) recur across games
- Match the mechanism to the game's scoring actions and favor reliability over feature count
- Arms and climbers need high reduction, position feedback, and a way to hold load without power
Go deeper
Lesson quiz
RequiredAnswer all 3 questions correctly to complete this lesson.
01.On a typical FRC robot, what is the primary job of an 'intake' mechanism?
02.Which factors are the key design considerations for a flywheel-style shooter?
03.A 'cascade' elevator differs from a 'continuous' elevator because a cascade elevator is rigged so that:
Answer every question to submit.
All 47 lessons in Mechanical, Build & Pneumatics
- Not started:Mini-Project 1: A Single-Jointed Arm From Math to Motion
- Not started:Mini-Project 2: A Two-Stage Cascade Elevator
- Not started:Mini-Project 3: A Velocity-Controlled Flywheel Shooter
- Not started:Mini-Project 4: A Pivoting Roller Intake
- Not started:Mini-Project 5: Integrating a COTS Swerve Module
- Not started:Pneumatics Won't Fire: A Full Diagnostic Tree
- Not started:The Robot Won't Drive Straight (and Other Drivetrain Sins)
- Not started:Gearboxes That Grenade and Fasteners That Vibrate Loose
- Not started:Closed-Loop Mechanisms That Oscillate, Sag, or Stall
- Not started:Field-Ready Reliability: Inspection, Spares, and the Pit Checklist
- Not started:Characterizing Any Mechanism with SysId
- Not started:Simulation-Driven Design with WPILib Physics Models
- Not started:Motion Profiling and Superstructure Coordination
- Not started:Designing for Weight, Stiffness, and Manufacturability
- Not started:Case Studies: Learning From Open Alliance Robots