Why Safety Standards Matter
A collaborative robot operating without proper safety compliance is a liability -- legally, financially, and physically. In the EU, non-compliant robots cannot carry the CE mark and cannot be legally deployed. In the US, OSHA citations for unguarded robotic hazards carry penalties up to $156,259 per willful violation. Even in research labs, universities require risk assessments before allowing student access to robot arms.
This guide explains the three core standards (ISO 10218-1, ISO 10218-2, ISO/TS 15066), the four collaborative operation modes, specific force and pressure limits by body region, the risk assessment process, and what compliance means in the US vs EU contexts.
The Three Core Standards
ISO 10218-1:2011 -- Robot Design
Covers the robot itself. Requirements include: emergency stop function (Category 0 or 1 per IEC 60204-1), protective stop, speed and force monitoring, singular posture management, joint limits, and control system safety integrity. All industrial and collaborative robots must comply with ISO 10218-1.
ISO 10218-2:2011 -- Robot System Integration
Covers the robot cell and integration. Requires a risk assessment per EN ISO 12100, defines safeguarding requirements (fencing, light curtains, safety mats, laser scanners), specifies verification and validation testing, and addresses the layout of the robot workspace. This standard applies to the integrator, not the robot manufacturer.
ISO/TS 15066:2016 -- Collaborative Operation
The critical standard for cobots. Defines the four collaborative operation modes and specifies quantitative force and pressure limits for human-robot contact. This is a Technical Specification (TS), not a full International Standard, meaning it is subject to revision. However, it is universally referenced by cobot manufacturers and regulators.
The Four Collaborative Operation Modes
1. Safety-Rated Monitored Stop (SMS)
The robot stops before the human enters the collaborative workspace and does not resume until the human exits. Requires safety-rated sensors (light curtains, laser scanners, pressure mats) to detect human presence. The stop must be a safety-rated stop per ISO 10218-1. This is the simplest mode but does not allow simultaneous human-robot work.
2. Hand Guiding
The operator physically moves the robot by grasping a hand-guiding device. The robot must have a safety-rated monitored stop that activates when the operator releases the guiding device (dead-man switch). Force/torque sensing at the hand-guiding point is required. This mode is used for teach-by-demonstration programming.
3. Speed and Separation Monitoring (SSM)
The robot dynamically adjusts speed based on the distance to the nearest human. Requires external monitoring systems (3D depth cameras, LiDAR, radar) to continuously measure separation distance. The minimum separation distance is calculated using ISO 13855 formulas that account for human approach speed (1.6 m/s), robot stopping time, and sensor response time. This is the most complex mode to implement correctly.
4. Power and Force Limiting (PFL)
The robot is inherently limited in the force and pressure it can exert. This is the default mode for most cobots (UR, FANUC CRX, Doosan). ISO/TS 15066 specifies maximum force and pressure values for different body regions.
ISO/TS 15066 Force and Pressure Limits
These limits define the maximum allowable force and pressure for transient (impact) and quasi-static (clamping) contact between a robot and a human body part:
| Body Region | Max Transient Force (N) | Max Quasi-Static Force (N) | Max Quasi-Static Pressure (N/cm2) |
|---|---|---|---|
| Skull / Forehead | 130 | 65 | 30 |
| Face | 65 | 45 | 20 |
| Neck (sides) | 150 | 75 | 25 |
| Upper arm / Elbow | 210 | 110 | 30 |
| Forearm | 190 | 100 | 40 |
| Hand / Fingers | 150 | 75 | 40 |
| Chest | 140 | 70 | 25 |
| Lower legs / Knees | 220 | 130 | 50 |
Key distinction: Transient contact is a brief impact (robot strikes and rebounds within 500 ms). Quasi-static contact is clamping (robot pins human against a fixed surface). Quasi-static limits are roughly half of transient limits because the human cannot escape.
Risk Assessment Methodology (EN ISO 12100)
Every cobot deployment requires a documented risk assessment. The process:
- Define scope: Identify the robot, application, workspace boundaries, and intended human interactions.
- Identify hazards: Mechanical (crushing, cutting, impact), electrical, thermal, noise. For each hazard, identify the hazardous situation (when/how the human is exposed).
- Estimate risk: For each hazard: severity of harm (S1-S4) x frequency of exposure (F1-F2) x probability of avoidance (P1-P2). Use ISO 13849-1 risk graph or EN 62061 SIL assignment.
- Reduce risk: Hierarchy: (a) inherently safe design (lower mass, speed, force), (b) safeguarding and protective devices, (c) information for use (training, signage, PPE).
- Document and validate: Produce a risk assessment report. Test the safety system against the documented risk scenarios. Re-assess when the application, tooling, or workspace changes.
Safety System Components
- Safety-rated laser scanners: SICK microScan3 ($2,000-$4,000). Defines configurable safety zones. When a human enters a warning zone, the robot slows; when entering a protective zone, the robot stops.
- Safety light curtains: Keyence SL-V ($1,500-$3,000). Detects objects crossing a light beam array. Used for entry/exit detection at cell boundaries.
- Safety-rated force/torque sensors: Built into cobots (UR, FANUC CRX) or external (ATI Gamma-SI, $8K-$15K). Must be safety-rated (SIL 2 or PLd minimum).
- Safety PLCs: Siemens SIMATIC Safety ($500-$2,000), Allen-Bradley GuardLogix. Required for SMS and SSM modes to process safety inputs and generate safety-rated outputs.
- Emergency stop buttons: Must be red mushroom-head, Category 0 or 1 stop per IEC 60204-1. One per access point to the robot workspace.
CE Marking and OSHA Requirements
EU: CE Marking
Robots sold in the EU must carry the CE mark, demonstrating compliance with the Machinery Directive 2006/42/EC. For cobots, this means compliance with ISO 10218-1/-2 and ISO/TS 15066. The manufacturer provides a Declaration of Conformity. The integrator is responsible for CE marking the complete installation (robot + tooling + safeguards).
US: OSHA and ANSI/RIA 15.06
The US does not require CE marking, but OSHA enforces workplace safety under the General Duty Clause (Section 5(a)(1)) and ANSI/RIA 15.06-2012 (US adoption of ISO 10218-2). OSHA considers ANSI/RIA 15.06 a recognized standard -- compliance provides a strong legal defense. For cobots, reference ANSI/RIA TR R15.606-2016 (US adoption of ISO/TS 15066).
Practical implication: If you deploy a cobot in a US workplace, you must conduct a risk assessment per ANSI/RIA 15.06 and document that the robot's force/speed limits comply with TR R15.606. SVRC can assist with risk assessments as part of our deployment services.