ISO/TS 15066 is the international technical specification for collaborative robot systems, published in 2016 under the title Robots and robotic devices – Collaborative robots. In robot safety and robotics, it supplements ISO 10218-1 and ISO 10218-2 by explaining how humans and industrial robots can share a workspace safely, and it is best known for its biomechanical limits on contact force and pressure for different regions of the human body.
The document is a technical specification rather than a full International Standard, which means it carries guidance with normative weight but was issued while the underlying research was still maturing. In practice, integrators, notified bodies and machine builders treat it as the reference for validating collaborative applications, and the 2025 revision of ISO 10218 brings much of its content into the main standard.
What ISO/TS 15066 specifies
ISO/TS 15066 specifies safety requirements for collaborative industrial robot systems and their work environment, building on the risk assessment process required by ISO 10218-2. It does not certify a robot as safe. Instead, it defines how a collaborative application, meaning robot, tool, workpiece and task together, is designed and verified.
Its content falls into three groups: design of the collaborative workspace, the requirements for each collaborative operation mode, and the methods for verification and validation. The informative Annex A contains the body model and limit values that make the document distinctive.
The table below summarizes the four collaborative operation modes that the specification describes.
| Mode | Principle | Contact with the person |
|---|---|---|
| Safety-rated monitored stop | Robot halts when a person enters the shared space | No contact while the person is present |
| Hand guiding | Operator moves the robot through a guiding device | Intentional, controlled contact |
| Speed and separation monitoring | Speed falls as the separation distance shrinks | Contact prevented by distance |
| Power and force limiting | Robot energy is limited so contact stays below thresholds | Contact allowed within body-region limits |
Body model and contact limits
The core of ISO/TS 15066 is a body model with 12 body regions and 29 specific body locations, each with a maximum permissible force and pressure. The values come from research on the onset of pain, not of injury, so they are deliberately conservative for routine contact in collaborative work.
The specification distinguishes quasi-static contact, where a body part is clamped between the robot and a fixed object, from transient contact, a short impact in which the body part can recoil. For transient contact, the permissible values may be up to twice the quasi-static limit, because the energy is absorbed over a brief period.
| Body region | Maximum quasi-static force | Note |
|---|---|---|
| Skull and forehead | 130 N | Contact should be avoided by design |
| Face | 65 N | Contact should be avoided by design |
| Chest | 140 N | Common region in bench-height cells |
| Hands and fingers | 140 N | Most frequent contact region in assembly |
| Lower arms and wrist | 160 N | Typical in reaching motions |
| Thighs and knees | 220 N | Highest tolerance in the model |
Pressure limits are listed separately for each body location, in newtons per square centimeter, and are often the binding constraint for sharp edges or small contact areas. A robot that respects the force limit can still exceed the pressure limit with a narrow gripper finger, which is why tool geometry matters as much as robot settings.
Speed, energy and separation calculations
ISO/TS 15066 links contact limits to robot motion through energy transfer calculations. Using an effective mass for the robot and for the body region, plus an effective spring constant, the integrator can estimate the maximum permissible relative speed at which a transient impact stays within the allowed force.
For speed and separation monitoring, the specification gives a formula for the protective separation distance. It adds the distance the person travels during the robot’s reaction and stopping time, the robot’s own reaction and stopping distances, an intrusion distance and measurement uncertainties of the sensing system and robot position.
| Input | Meaning | Typical source |
|---|---|---|
| Human approach speed | Assumed walking or reaching speed | Values from ISO 13855, often 1.6 to 2.0 m/s |
| Robot reaction time | Delay before the stop begins | Safety controller data |
| Robot stopping distance | Travel during braking | Measured stopping performance |
| Intrusion distance | Body part reach past the detection zone | Sensor resolution |
| Position uncertainty | Error of sensor and robot measurement | Device specifications |
ISO/TS 15066 compared with related standards
ISO/TS 15066 sits inside a family of machinery safety documents and never applies alone. Each neighbor answers a different question, and a collaborative cell normally references several of them.
| Document | Scope | Relation |
|---|---|---|
| ISO 10218-1 | Safety of the robot itself | Defines robot-level safety functions the TS relies on |
| ISO 10218-2 | Robot systems and integration | Parent document that the TS supplements |
| ISO 13849-1 | Safety-related parts of control systems | Sets performance levels for safety functions |
| ISO 12100 | General risk assessment | Framework for the risk assessment |
| ISO/TR 20218-1 | End-effector safety | Guidance on gripper and tool hazards |
A frequent misunderstanding is that a collaborative robot is compliant with ISO/TS 15066 by itself. The robot arm only provides functions such as force monitoring; compliance belongs to the application, including the tool, the workpiece and the motion paths.
Applying ISO/TS 15066 in practice
Applying ISO/TS 15066 starts with a task-based risk assessment that identifies every possible contact: which body region, whether clamping is possible, and at what speed. The integrator then chooses a collaborative mode, sets speed and force limits and measures actual contact forces with a calibrated force and pressure measuring device.
- Measure, do not assume. Settings in the robot controller are not proof; pressure film and force gauges confirm real values.
- Eliminate head contact. Layout and motion paths should keep the robot away from head height.
- Watch clamping points. Quasi-static contact near fixtures is the most common cause of exceeded limits.
- Revalidate after changes. A new gripper, payload or path invalidates earlier measurements.
- Document everything. The validation report supports the declaration of conformity for the machine.
Understanding it simply
ISO/TS 15066 is the rulebook for robots that work right next to people without a fence. It explains the safe ways a robot and a worker can share a table, such as the robot stopping when someone comes close or slowing down as a person approaches.
Its most famous part is a map of the human body with limits for each area. A hand can accept a firmer bump than a face, so the robot must push more gently wherever it might touch a sensitive spot. The key idea is simple: contact may happen, but it must never hurt.
Applied in practice
A manufacturer of electrical cabinets installs a collaborative robot that screws mounting rails while a worker inserts components at the same bench. The risk assessment shows that the worker’s hands and lower arms could be clamped between the screwdriver and the rail, so the integrator selects power and force limiting as the collaborative mode.
First measurements with a force gauge reveal about 180 N of quasi-static force at one clamping point, above the 140 N limit for hands. The team reduces the approach speed near the rail, rounds the screwdriver housing to spread pressure and repeats the tests. The final validation shows all measured values below the body-region limits, and the cell enters production without fencing.