Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
IEC TR 63065: Industrial Automation — Functional Safety for Collaborative Robots
Safety requirements and risk assessment framework for human-robot collaboration without fixed guarding
IEC TR 63065 addresses the functional safety requirements specific to collaborative robot (cobot) systems operating alongside human workers without fixed guarding. As a technical report, it provides guidance on applying the ISO 13849 and IEC 62061 safety standards to collaborative applications, while also addressing the unique risk scenarios that arise from human-robot interaction. The document covers four types of collaborative operations defined in ISO 10218-2: safety-rated monitored stop, hand guiding, speed and separation monitoring, and power and force limiting.
Unlike traditional industrial robots confined to safety cages, collaborative robots must achieve acceptable risk levels through inherent design, not just safeguarding. IEC TR 63065 provides the framework for this paradigm shift.
Risk Assessment for Human-Robot Collaboration
The standard introduces a systematic risk assessment methodology tailored to collaborative workspaces. Engineers must evaluate not only traditional hazards (crushing, shearing, entraprnment) but also application-specific risks such as transient contact forces during hand-guiding operations, unexpected robot start-up during tool changes, and cumulative trauma from repetitive collaborative tasks. The risk graph approach from IEC 62061 is extended with collaborative-specific parameters: contact speed, clamping distance, energy of moving parts, and operator training level. The performance level (PL) required for each safety function is determined by combining these parameters with severity, exposure, and avoidance likelihood.
| Collaborative Mode | Primary Hazard | Required PL | Typical Safety Measures |
|---|---|---|---|
| Safety-rated monitored stop | Unexpected robot motion during operator access | PL d (ISO 13849-1) | Dual-channel safety PLC, redundant contactors |
| Hand guiding | Crushing between robot arm and environment | PL d | Enable device with 3-position switch, limiting speeds <250 mm/s |
| Speed & separation monitoring | Striking from unexpected motion | PL c – PL d | Safety-rated laser scanners, vision systems, minimum separation distance |
| Power & force limiting | Transient impact or clamping injuries | PL c | Force/torque sensing, rounded edges, series elastic actuators |
A common pitfall in collaborative robot cell design is assuming that power and force limiting alone suffices for all applications. When a cobot handles a sharp or heavy tool, the risk may escalate beyond what PL c can mitigate, requiring additional safeguarding or reclassification to a different collaborative mode.
Engineering Design Insights for Cobot Safety Systems
Designing safety-certified collaborative robot cells involves several critical engineering decisions. First, the choice of safety controller architecture matters: while safety-rated PLCs offer flexibility for complex logic, hardwired safety relay circuits provide higher reliability for simple e-stop and guard monitoring functions. Second, speed and separation monitoring (SSM) requires accurate pose estimation of both the robot and the operator. The standard recommends using multiple heterogeneous sensors — combining laser scanners with vision-based human tracking — to achieve the required PL d reliability while minimising false stops that reduce productivity. Third, for power and force limiting (PFL) applications, the bio-mechanical limits specified in ISO/TS 15066 must be strictly observed. These limits are joint-specific and depend on whether the contact is transient (impact) or quasi-static (clamping). Engineers must verify PFL performance through both simulation and physical force measurement during commissioning.
Modern collaborative robot cells implementing IEC TR 63065 guidelines have demonstrated up to 40% improvement in overall equipment effectiveness (OEE) compared to traditional caged robot cells, while maintaining equivalent safety performance.
Verification and Validation Requirements
The standard requires a comprehensive verification and validation (V&V) process. Verification confirms that the safety functions are implemented according to the safety requirements specification, while validation confirms that the overall risk reduction meets the required level. Key V&V activities include: (a) fault injection testing of safety circuits; (b) measurement of stopping distances and times under worst-case payload conditions; (c) force and pressure measurement at each body region for PFL applications; (d) separation distance calculation verification accounting for robot overshoot, sensor response time, and brake wear.
Q1: Can a collaborative robot be used without any additional safeguarding?
A: Not generally. Even power-and-force-limiting cobots require a risk assessment. If the risk assessment identifies hazards that cannot be inherently reduced, additional safeguarding (e.g., light curtains, pressure-sensitive mats) or administrative controls (e.g., restricted access, training) must be implemented.
A: Not generally. Even power-and-force-limiting cobots require a risk assessment. If the risk assessment identifies hazards that cannot be inherently reduced, additional safeguarding (e.g., light curtains, pressure-sensitive mats) or administrative controls (e.g., restricted access, training) must be implemented.
Q2: What is the maximum allowed speed for hand-guiding mode?
A: ISO 10218-1 specifies that hand-guiding speed must be limited to 250 mm/s during collaborative operation. Higher speeds may be used if risk assessment demonstrates that equivalent safety is maintained through other measures.
A: ISO 10218-1 specifies that hand-guiding speed must be limited to 250 mm/s during collaborative operation. Higher speeds may be used if risk assessment demonstrates that equivalent safety is maintained through other measures.
Q3: How is the minimum separation distance calculated for SSM mode?
A: The minimum separation distance S = (robot speed x response time) + (operator speed x response time) + intrusion distance + safety margin. Standard parameters assume operator speed of 1.6 m/s and robot stopping time including brake engagement delay.
A: The minimum separation distance S = (robot speed x response time) + (operator speed x response time) + intrusion distance + safety margin. Standard parameters assume operator speed of 1.6 m/s and robot stopping time including brake engagement delay.
Q4: Does IEC TR 63065 apply to mobile collaborative robots?
A: Yes, the standard addresses mobile cobots (autonomous mobile robots with manipulators). Additional hazards include vehicle collision, tip-over, and floor surface integrity. The mobile platform must have its own safety-rated control system meeting PL d, with redundant braking and obstacle detection.
A: Yes, the standard addresses mobile cobots (autonomous mobile robots with manipulators). Additional hazards include vehicle collision, tip-over, and floor surface integrity. The mobile platform must have its own safety-rated control system meeting PL d, with redundant braking and obstacle detection.
