The Hierarchy of Controls Applied to FRC

The NIOSH/OSHA Hierarchy of Controls ranks hazard controls from most to least effective: Elimination > Substitution > Engineering controls > Administrative controls > PPE. The top three protect people without depending on human behavior, so they are far more reliable than ‘be careful’ rules. Most FRC teams jump straight to PPE; advanced teams climb the hierarchy first.

Worked application - a high-speed flywheel shooter:

1. Elimination - Can you avoid the hazard entirely? If a mechanism doesn’t need an exposed spinning mass, remove it. Not always possible, but always the first question.
2. Substitution - Replace the hazard with something safer. Swap surgical tubing under high tension for a constant-force spring with a captured housing, or a brushed motor near a pinch point for a geared brushless drive that can be current-limited precisely.
3. Engineering controls - Isolate people from the hazard with the design itself: polycarbonate guards over the flywheel, covers over pinch points and belts, rounded edges (sharp protrusions are an inspection concern), and firmware guards. Setting a TalonFX SupplyCurrentLimit and a software brownout level (RobotController.setBrownoutVoltage on roboRIO 2.0) are engineering controls that prevent a hazard in code. So is a properly wired RSL that tells everyone when the robot is live.
4. Administrative controls - Change how people work: a written LOTO procedure, a two-person robot-move rule, machine-operator sign-offs, and the opening-day pit checklist. These rely on compliance, so they sit below engineering controls.
5. PPE - The last line: ANSI Z87.1 safety glasses, gloves, hearing protection. Necessary, but never the only defense.

The key insight: a guard bolted over your flywheel and a current limit in your code are higher-order controls than a sign saying ‘careful, spinning parts.’ Document each significant hazard and note which level of control you applied - and push every hazard as high up the hierarchy as the design allows. NIOSH notes a combination is often needed (e.g., a guard plus a procedure plus glasses), which is exactly what mature safety programs show.

Mini-exercise: list your robot’s top five hazards (flywheel, climber spring, pinch points, battery, sharp edges) and assign the highest-feasible control to each. Where you’re stuck at ‘PPE,’ ask whether an engineering control could move it up.

Key takeaways

• Climb the hierarchy: elimination, substitution, and engineering controls beat administrative rules and PPE.
• Guards, rounded edges, current limits, and a correct RSL are engineering controls designed into the robot.
• Document each hazard with the highest feasible control level - don’t default to PPE.

This lesson was adapted from learnfrc.com.