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Safety·Lesson 24 of 28

The Hierarchy of Controls Applied to FRC

Use NIOSH's five-level hierarchy to design hazards out of the robot and shop instead of relying on PPE.

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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.

Go deeper

Lesson quiz

Required

Answer all 3 questions correctly to complete this lesson.

1.In the NIOSH Hierarchy of Controls, which control type is the MOST effective at protecting people?

2.Why are elimination, substitution, and engineering controls considered more reliable than administrative controls and PPE?

3.Adding a fixed guard over the rotating chuck of a shop lathe is an example of which level of the hierarchy?

Answer every question to submit.