ISO/TS 15066 Body Region Force and Pressure Limits: Complete Reference Table

ISO/TS 15066 defines force and pressure limits for a body model of 29 specific body areas grouped into 12 body regions. Each region has a spring constant ranging from 10 N/mm (abdomen) to 150 N/mm (skull and forehead) that determines how impact force is absorbed by body tissue. These values drive all compliance testing for collaborative robot installations.

This page is a working reference. The full body region table with spring constants is organized for engineers who need specific values during risk assessment, body region mapping, or compliance testing. For the actual force and pressure limit values in Newtons and N/cm², always reference the current version of ISO/TS 15066 or ISO 10218-2:2025 directly.

For standards background, see Collaborative Robot Safety Standards. For the testing process, see the Cobot Safety Testing Guide.

The Complete Body Region Table

All 12 body regions from ISO/TS 15066 Table A.3, with spring constants and notes on where each region is typically relevant in cobot installations. The region numbers are the standard’s own, running 1 to 12 from head to foot.

The spring constants above are the values from ISO/TS 15066 Table A.3, which pairs each region with an effective mass for the contact model. They’re quoted for contact areas of roughly 1 cm². The specific force limits (in Newtons) and pressure limits (in N/cm²) for transient and quasi-static contact live in Table A.2, broken out per specific body area rather than per region. Reference ISO/TS 15066 or ISO 10218-2:2025 directly for those values.

Understanding Spring Constants

The spring constant for each body region represents the mechanical stiffness of the tissue: how much the body deforms under a given force. A higher spring constant means a stiffer region. The skull at 150 N/mm barely deforms on impact. The abdomen at 10 N/mm compresses significantly under the same force.

This matters for measurement for a specific reason. A rigid load cell reads the same number regardless of what surface it’s simulating. The human body doesn’t work that way. When a robot contacts the skull, most of the impact energy transmits directly because the skull doesn’t deform much. When it contacts the abdomen, the tissue absorbs more energy before the force peaks. The measured peak forces are different even at the same robot speed and payload.

A biofidel measurement system uses spring elements calibrated to match each body region’s stiffness. The transducer compresses at the same rate as the tissue it represents, so the measured force reflects what the body would actually experience. That’s why generic load cells don’t give valid compliance readings for ISO/TS 15066, and why the standard requires biofidel measurement.

The 15x range from the softest region (10 N/mm) to the stiffest (150 N/mm) means a single-spring measurement device can’t cover all 12 body regions accurately. Compliance testing requires matching the transducer to the region being tested.

Body Region Groups

Head and Neck (Regions 1 to 3)

The range from 50 N/mm (neck) to 150 N/mm (skull and forehead) covers the stiffest structures in the model. Head contact scenarios in cobot installations typically involve overhead robot paths, ceiling-mounted arms, or tall operators whose head height intersects the robot’s working envelope. Watch the asymmetry here. ISO/TS 15066 publishes limits for the skull, forehead, and face, then states that contact with those areas isn’t permissible. The numbers exist so you can model an event you’re required to prevent. Neck contact is less common in most factory layouts, but the injury potential is high enough that it belongs in the risk assessment whenever the robot’s path reaches shoulder or head height.

Torso (Regions 4 to 7)

All four torso regions fall below 40 N/mm, making this the group with the lowest spring constants overall. The practical consequence is lower force limits and more restrictive clamping scenarios. The chest (5) and abdomen (6) are the most common clamping risk points. An operator leaning toward a conveyor can be trapped between the robot and the fixed structure. Back and shoulder (4) contact appears in layouts where operators face away from the robot during part loading.

Arms and Hands (Regions 8 to 10)

Hands and fingers at 75 N/mm are the most common first contact point in collaborative robot applications. Operators reach in to load parts, adjust workpieces, and clear jams. The standard treats this region in more detail than any other, splitting it into 9 specific body areas that separate the dominant from the non-dominant hand. Lower arms and wrist joints (40 N/mm) appear in the same scenarios. Upper arms and elbow joints (30 N/mm) are more relevant in side-by-side layouts where the operator and robot work on the same fixture from different sides.

Legs (Regions 11 to 12)

The leg group runs from 50 to 60 N/mm, stiffer than the torso and close to the neck. These body regions matter most for low-mounted cobots, robots operating below worktable height, mobile platforms, and AGVs. One quirk worth knowing before you model a contact: the standard sets the effective mass for thighs, knees, and lower legs to the operator’s full body weight, because a standing person can’t pull a leg back out of the way. The model stops at the lower legs. There’s no feet or toes region, so a floor-level contact scenario has no body region of its own to map to. A risk assessment for a fixed arm robot at standing height might reasonably exclude leg contact. The same assessment for a mobile cobot or a floor-level application shouldn’t.

How to Use This Table

The spring constants determine your testing equipment. Every other step follows from that.

The mapping from CoboSafe transducer models to body region spring constants follows directly from this table.

CoboSafe covers all 12 body regions with 9 transducers. The 12 regions resolve to 9 distinct spring constants, so a single transducer serves more than one region wherever the values coincide (face and hands both sit at 75 N/mm, chest and pelvis both at 25). The selection is always driven by the spring constant for the region being tested, not by a transducer number or model preference.

For more on the full testing process, see the Cobot Safety Testing Guide and the Cobot Risk Assessment Guide.

Important Notes on the Standard

Frequently Asked Questions