Collaborative Robot Safety Standards: ISO 10218, OSHA, and CE Marking

Collaborative robot safety standards are anchored in three international documents: ISO 10218-1 and ISO 10218-2, both revised in 2025, and the biomechanical contact limits originally published as ISO/TS 15066 and now folded into the 2025 edition of ISO 10218-2. The United States adopts both ISO parts verbatim as ANSI/A3 R15.06-2025¹, and OSHA enforces the same expectations through the General Duty Clause, machine guarding rules, and lockout/tagout. In the European Union, the harmonized versions of the ISO standards supply the technical basis for CE marking under Machinery Regulation (EU) 2023/1230.

The Two Halves of ISO 10218

ISO 10218 splits responsibility between the two companies that put a robot into a workplace. Part 1 applies to the robot manufacturer. Every industrial robot must ship with emergency stop capability, protective stop inputs, speed and position monitoring, and fault detection in safety-critical circuits. The manufacturer also has to document the robot’s safe operating limits and describe what the machine can and cannot do safely.²

Part 2 applies to the system integrator, meaning the company that installs the robot into an actual production line. The integrator owns the complete application: end-of-arm tooling, workspace layout, how the robot interacts with conveyors or other machines, and the physical and electronic safeguards that protect nearby workers. The 2025 revision emphasizes the “robot application” as a whole rather than just the “robot system,” reflecting the reality that safety depends on how the robot is used, not only how it is built.³

If the manufacturer ships a robot without the required safety hardware, or the integrator installs a compliant robot into an unsafe application, the chain breaks.

Contact Force and Pressure Limits

The technically specific piece of the framework is a table of biomechanical thresholds that map the human body into regions and assign maximum force and pressure values for each. The numbers represent the onset of pain or the smallest energy transfer that could produce a minor injury like a bruise. Engineers use them to calculate whether a given robot, moving at a given speed with a given payload, could hurt someone on contact.⁴

Two contact types matter. Quasi-static contact clamps a body part between the robot and a fixed surface with no escape route. Transient contact is a brief collision from which the person can move away. Transient limits are generally twice the quasi-static limits because the energy transfer is shorter. Representative quasi-static limits from Annex A of the standard:

Face: 65 N maximum force, 110 N/cm² maximum pressure
Chest (sternum): 140 N maximum force, 120 N/cm² maximum pressure
Hand (palm): 140 N maximum force, 260 N/cm² maximum pressure
Skull and forehead: 130 N maximum force, 130 N/cm² maximum pressure

The face and skull are critical zones. Transient multipliers do not apply there, so any contact with the head must stay below the quasi-static limits no matter how brief. For context, 65 N on the face is about the force of a 6.5-kilogram weight resting on your cheek. That is not much, which is why collaborative robots tend to be smaller and lighter than their fenced industrial counterparts. The 2025 revision of ISO 10218-2 incorporated these limits directly, converting them from supplementary guidance into a formal requirement.

Collaborative Operation Modes

The standards recognize four ways a person and a robot can share a workspace during normal operation. Any given application relies on one or a combination.

Hand-Guided Control

The operator grasps a handle mounted on the robot and moves the arm by hand, usually to teach paths or position heavy loads. An enabling device on the handle means the robot only moves when the operator deliberately allows it. Release the handle and the robot stops. In this mode the robot functions as a powered tool under direct human control.²

Speed and Separation Monitoring

Laser scanners, vision systems, or similar sensors track the distance between the robot and any nearby person. The robot runs at full speed when the area is clear, slows as a person approaches, and stops if the separation drops below a calculated minimum. That minimum accounts for the robot’s braking distance, the reaction time of the safety system, and the speed at which a person can walk toward the hazard. This mode fits applications where the human and robot take turns rather than working on the same part at once.⁴

Power and Force Limiting

This is the mode that made the current generation of lightweight cobots commercially viable. The robot continuously monitors its own torque and contact forces and stops or reverses if a threshold is exceeded. Rounded surfaces, padded joints, and the elimination of pinch points reduce injury potential in the hardware itself. Because the robot inherently limits the energy it can transfer during a collision, it can work alongside people without external sensors watching the gap. The trade-off is speed, payload, and reach compared to fenced arms.

Safety-Rated Monitored Stop

Under the earlier framework this was a standalone collaborative mode. The robot keeps power on but freezes all motion when a person enters the shared workspace and resumes only after the person leaves. In the 2025 revision of ISO 10218-1, the same result is achieved through the protective stop function, which triggers when any external safety device detects a person. The practical effect is unchanged: the robot holds position under power but does not move while anyone is within range.

Stop Categories

Robot safety systems use three stop categories originally defined in IEC 60204-1. Which category applies depends on what triggered the stop.

Category 0: Immediate removal of drive power. The robot coasts to a stop or brakes mechanically with no controlled deceleration. Used when safety limits are exceeded or a fault is detected.
Category 1: Controlled deceleration, then power removal once the robot reaches standstill. This is the standard emergency stop triggered by the red mushroom-head button.
Category 2: Controlled stop with drive power maintained after the robot stops. The robot holds position actively. Typical for protective stops driven by light curtains or laser scanners.

ISO 10218-1:2025 requires that every industrial robot provide emergency stop (category 0 or 1), protective stop (category 0, 1, or 2), and normal stop (category 2) functions. The category chosen for a given situation depends on the risk assessment.²

How OSHA Enforces Robot Safety in the United States

ANSI/A3 R15.06-2025 is a direct national adoption of both ISO 10218-1:2025 and ISO 10218-2:2025 in their entirety. It replaces ANSI/RIA R15.06-2012.¹

OSHA has no regulations written specifically for robots. The agency’s own robotics standards page says so, and treats the ANSI and RIA documents as consensus guidance rather than binding rules.⁵

Noncompliance still carries consequences through three enforcement channels. The General Duty Clause, Section 5(a)(1) of the OSH Act, requires every employer to furnish a workplace “free from recognized hazards that are causing or are likely to cause death or serious physical harm.”⁶ The machine guarding standard at 29 CFR 1910.212 requires protection from points of operation, nip points, and rotating parts. The lockout/tagout standard at 29 CFR 1910.147 applies whenever the equipment is serviced or maintained. Inspectors regularly cite industry consensus standards like ANSI/A3 R15.06 to establish that a hazard was “recognized,” which is why treating the voluntary standards as optional rarely holds up.

OSHA penalties as of January 2025 reach $16,550 per serious violation and $165,514 per willful or repeated violation. Failure to correct a cited hazard costs $16,550 per day past the abatement deadline.⁷

Lockout/Tagout for Collaborative Robots

Because cobots are designed for close human proximity during normal operation, some users assume energy isolation rules do not apply. They do, but only in specific circumstances.

Under 29 CFR 1910.147, lockout/tagout is required during servicing and maintenance whenever unexpected startup or energy release could injure someone. It is also required during normal production if a worker must remove or bypass a safety device, or place a body part into the machine’s point of operation or an associated danger zone during its operating cycle.⁸

An exception exists for minor tool changes and adjustments that are routine, repetitive, and integral to production, if alternative protective measures are in place. For cobots, that exception often covers tasks like swapping a gripper finger or adjusting a fixture while the robot is in a protective stop. The controlling question is whether the worker’s hands enter a danger zone while the robot retains the ability to move. Push buttons and selector switches do not count as energy-isolating devices under the standard, so pressing “pause” on a teach pendant does not satisfy lockout requirements for maintenance work.

EU Compliance and CE Marking

Anyone selling collaborative robots into the EU should track the transition from the Machinery Directive (2006/42/EC) to Machinery Regulation (EU) 2023/1230, which applies from January 20, 2027. The regulation specifically addresses autonomous mobile machinery, connected equipment, and artificial intelligence used in safety functions, areas the older directive did not cover directly.⁹

Under either framework, any collaborative robot placed on the European market must carry CE marking to signal that the product meets the essential health and safety requirements in the regulation’s Annex III. Manufacturers demonstrate compliance through a conformity assessment procedure and issue an EU declaration of conformity. The harmonized versions of the ISO standards, published as EN ISO 10218-1:2025 and EN ISO 10218-2:2025, provide a presumption of conformity with the mechanical and safety requirements, making them the practical roadmap for CE marking a cobot system in Europe.

Risk Assessment

Every collaborative robot application requires a documented risk assessment before it goes live. Both ISO 10218-1 and ISO 10218-2 require this, and the 2025 revision raised the bar for how thorough and well-documented the assessment must be.

The assessment identifies every point where a person could be pinched, crushed, struck, or caught by the robot, its tooling, or the workpiece. It covers the intended operation and reasonably foreseeable misuse. Someone leaning into the work zone to retrieve a dropped part is foreseeable even if written procedure forbids it. The assessment estimates the likelihood and severity of each hazard, then documents what protective measures reduce the risk to an acceptable level.³

It is not a one-time exercise. Any change to tooling, task, layout, payload, or speed requires the assessment to be revisited. The resulting documentation is the primary evidence of compliance during a regulatory inspection or after an incident.

Training: Authorized Versus Affected Personnel

OSHA does not publish a training curriculum specific to collaborative robots. Training obligations flow from the general duty to protect workers and from the standards that apply to the workplace, particularly lockout/tagout and machine guarding. The agency’s robotics page references RIA TR R15.706, a technical report that expands on the user’s responsibilities for operating and maintaining robot systems, as relevant industry guidance.⁵

The distinction that matters most is between authorized and affected personnel. Authorized personnel perform hands-on tasks like programming, maintaining, or locking out the robot. They need to understand the specific energy sources, the safety system architecture, and the correct isolation procedures. Affected personnel work near the robot but do not service it. Their training focuses on recognizing when the robot is in a safe state, understanding indicator lights and stop conditions, and knowing what to do if something goes wrong. Treating both groups identically wastes time; skipping training for either creates real exposure.

1
ANSI. ANSI/A3 R15.06-2025 – Industrial Robots and Robot Systems
2
International Organization for Standardization. ISO 10218-1:2025 – Robotics – Safety Requirements – Part 1: Industrial Robots
3
International Organization for Standardization. EN ISO 10218-2:2025 – Robotics Safety Requirements for Industrial Robot Applications and Robot Cells
4
International Organization for Standardization. ISO/TS 15066 – Robots and Robotic Devices – Collaborative Robots
5
Occupational Safety and Health Administration. Robotics – Standards
6
Occupational Safety and Health Administration. OSH Act of 1970 – Section 5 – Duties
7
Occupational Safety and Health Administration. OSHA Penalties
8
Occupational Safety and Health Administration. 1910.147 – The Control of Hazardous Energy (Lockout/Tagout)
9
European Agency for Safety and Health at Work. Regulation 2023/1230/EU – Machinery