🔧 Hardware · Engineer · Intermediate
End-Game Mechanisms
End-game is often the highest point differential in close matches. This guide covers Push Back end-game scoring, mechanism tradeoffs, ratchet builds, timing your move, and the practice protocol that separates consistent end-game from missed opportunities.
Before this guide: You have a working robot with a functional scoring mechanism. End-game hardware is an addition, not a first build. Don't start here.
🏆 Push Back End-Game Scoring
In Push Back 2025-26, end-game scoring includes parking and elevation bonuses. The final 30 seconds of the match are when these points are contested. Key timing:
| Time remaining | Action | Notes |
|---|
| 0:30 | Last scoring cycle | Complete your final block score before committing to end-game |
| 0:20 | Navigate to end-game position | Must be in position with 10s buffer — don't cut it to 5s |
| 0:10 | Execute end-game action | Trigger mechanism, confirm position, hold until buzzer |
| 0:00 | Hold position | Don't move after buzzer — robots must be in final position |
Never sacrifice a 3-point block score for a 2-point parking bonus. Calculate the expected value before adding end-game to your cycle. Some robots should skip dedicated end-game hardware entirely.
⚖ Dedicated Hardware vs. Existing Mechanism
| Approach | Pros | Cons |
|---|
| Dedicated end-game mechanism | Optimized for one task, fast and reliable when built well | Adds weight, motor count, and complexity. Another thing to break |
| Repurpose existing mechanism | No extra weight. Uses what's already proven | Must transition smoothly. The mechanism must physically reach end-game position |
| Drive-only positioning | Simplest. Zero added mechanism risk | Only works for parking-type end-game, not elevation |
🔩 Building a Ratchet or Release Mechanism
Linear Ratchet (one-way lock)
A ratchet pawl engages a rack or sprocket to allow motion in one direction and lock in the other. Common for lift locks that hold elevation without motor current.
✓ Holds position without burning motor. ✓ Reliable under load. ✓ No code required to hold.
✗ Must disengage to return. ✗ Requires precise pawl geometry — test before competition.
Pneumatic Release
A pneumatic piston releases a stored spring or rubber band mechanism at end-game. One shot — no motor needed. Trigger with a button press.
✓ Instant deployment. ✓ No motor budget used. ✓ Very repeatable.
✗ One-shot only per match. ✗ Air tank management. ✗ Banned in some competition configurations — verify legality.
Motor-Driven with Brake Hold
A dedicated motor drives the end-game mechanism, then holds position using HOLD brake mode. Simplest code path.
✓ Fully controllable. ✓ Easy to program. ✓ Can reverse if needed.
✗ Uses a motor slot. ✗ Motor must not overheat holding the load for 10+ seconds.
💻 Programming the Transition
// In opcontrol — trigger end-game on button press
if (controller.get_digital(pros::E_CONTROLLER_DIGITAL_Y)) {
endgame_motor.move_absolute(TARGET_POSITION, 80);
endgame_motor.set_brake_mode(pros::E_MOTOR_BRAKE_HOLD);
}
// Time-based auto-trigger at 30 seconds remaining (match = 105s total)
if (pros::millis() > 75000 && !endgame_triggered) {
endgame_triggered = true;
// Flash Brain screen to alert driver
pros::lcd::print(0, "END-GAME — ACTIVATE NOW");
}
🎯 Practice Protocol for End-Game Consistency
- Dry run from full field position: Start at your last scoring position. Drive to end-game position. Execute. Time it. Repeat 10 times.
- Target: under 12 seconds total. If it takes 15s+, your path is too long or mechanism is too slow.
- Practice failing gracefully: What happens if you miss? Can you still park? Train the fallback, not just the ideal run.
- Add to every match sim: Every full-match practice should include the end-game transition. Don't practice it separately — integrate it.
- Test under match conditions: Run end-game with a full battery and a warm robot. Cold bench tests don't reproduce competition behavior.
Endgame mechanism design requires Failure Mode and Effects Analysis (FMEA) — a reliability engineering method that systematically identifies every way a mechanism can fail and its probability. For endgame mechanisms, any failure during the final 30 seconds cannot be recovered. FMEA drives design toward simplicity: each additional mechanical step multiplies failure probability, so minimum-step designs maximize reliability.
🎤 Interview line: “We ran FMEA on our endgame mechanism before building it. Three-step endgame at 95% per step: 0.95 cubed = 85.7% match reliability. Two-step alternative at 95%: 0.95 squared = 90.25%. We chose the two-step design and accepted lower maximum points because the reliability math justified it. Our endgame success rate was 89% across the season.”
Adding a 600g hang mechanism raises your center of mass. What must you verify before competition?
⬛ The robot's weight is still under the 15kg VRC limit
⬛ The robot still tips forward onto its bumpers rather than falling backward — a high CG can cause unintended tipping during rapid direction changes
⬛ The mechanism doesn't extend beyond 18 inches in its retracted state
📝Notebook entry tip: Select Best Solution — Purple slide — Write a decision matrix for your endgame mechanism: list all options, their step count, estimated reliability, and point value. Calculate expected value (probability x points) for each. Document why you chose the mechanism you did — the math that justified simplicity over higher theoretical scoring is the engineering reasoning judges want to see.