Force & Pressure Limits: How to Validate Cobot Applications
Collaborative robots are designed to share workspace with humans — but only within strict biomechanical limits. ISO/TS 15066 defines force and pressure thresholds to ensure safe contact during unintended collisions.
Understanding the Limits
The standard lists maximum transient and quasi-static contact forces for 29 body regions. For example:
- Hand: 140 N transient, 70 N quasi-static
- Arm: 150 N transient, 90 N quasi-static
- Head: 65 N transient, 65 N quasi-static
Values depend on contact area and motion speed — and must be validated through measurement, not estimation.
Validation Methods
- Use a certified collision measurement device (per ISO/TS 15066 Annex A).
- Test in all relevant operating modes and positions.
- Adjust robot speed, payload, or path to meet safe limits.
- Document test results in the risk assessment file.
Engineering Controls
- Use power and force limiting (PFL) functions built into the robot controller.
- Limit tool geometry to increase contact surface area.
- Install soft covers or torque sensors for additional compliance.
Case Example: Automotive Final Assembly
A cobot performing adhesive application was validated at 80 N max contact force, passing ISO/TS 15066 criteria. The integrator used automated measurement devices linked to robot scripts for verification.
Related Articles
- ISO 10218 Made Simple: Integrator Playbook for 2025
- Functional Safety for Robotics: PL, SIL, and Safe Motion
- Collaborative vs Industrial Robot Safety: What Changes
Conclusion
Validating cobot safety isn’t optional. Measured compliance with ISO/TS 15066 protects both workers and integrators — ensuring robots operate safely without compromising performance.
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