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

ISO/TS 15066 defines force and pressure limits for 15 body region categories (29 specific locations) during human-robot contact. Each region has a spring constant ranging from 10 N/mm (abdomen, larynx) to 150 N/mm (skull) 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 15 body regions from ISO/TS 15066 Table A.2, with spring constants and notes on where each region is typically relevant in cobot installations.

Code	Body Region	Spring Constant (N/mm)	Where It's Relevant
1.1	Skull / Forehead	150	Overhead robot paths; tall operators; ceiling-mounted cobots. Stiffest region in the table.
1.2	Face	75	Overhead or front-approach paths. Sensory organ proximity means quasi-static limits are especially restrictive.
1.3	Neck (sides)	50	Horizontal robot arms at shoulder height. Lateral contact during over-shoulder reach tasks.
1.4	Neck (front / larynx)	10	Front-approach paths at neck height. Among the lowest spring constants. Highest injury severity.
2.1	Back / Shoulders	35	Operators turning away from the robot. Loading operations where the back faces the robot path.
2.2	Chest	25	Clamping risk near conveyors and fixed structures at torso height. Common quasi-static scenario.
2.3	Belly	10	Softest torso region. Lowest spring constant alongside the larynx. Low force limits for both contact types.
2.4	Pelvis	25	Standing-height horizontal robot paths. Relevant for operators standing at workcell fixtures.
2.5	Buttocks	15	Seated workstations where the robot operates behind or beside the operator.
3.1	Upper Arm / Elbow	30	Side-by-side cobot layouts. Common contact zone for collaborative assembly tasks.
3.2	Lower Arm / Wrist	40	Manual load/unload tasks. Operators reaching into the cell while the robot is nearby.
3.3	Hand / Fingers	75	Most common contact point in cobot applications. Test this region first in most installations.
4.1	Thigh / Knee	50	Low-mounted robots. Operators seated at workcells with robot paths below table height.
4.2	Lower Leg	60	Mobile robot bases and AGV contact paths at shin height.
4.3	Feet / Toes	75	Floor-level automated guided vehicles and mobile cobots. Often overlooked in fixed-cell risk assessments.

The spring constants above are confirmed values from ISO/TS 15066 Table A.2. The specific force limits (in Newtons) and pressure limits (in N/cm²) for transient and quasi-static contact are defined in the standard. 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 10x range from the softest regions (10 N/mm) to the stiffest (150 N/mm) means a single-spring measurement device can’t cover all 15 body regions accurately. Compliance testing requires matching the transducer to the region being tested.

Body Region Groups

Body Region Groups and Testing Priority

Head and Neck (1.1–1.4) Spring constants: 10–150 N/mm. The widest variation of any group. The skull is the stiffest structure; the larynx is among the most vulnerable. Head contact typically involves overhead robot paths or tall operators. Neck contact is less common but carries the highest injury severity in this group.

Torso (2.1–2.5) Spring constants: 10–35 N/mm. Generally softer regions with lower force limits. The most common clamping scenarios involve the chest and belly against fixtures or conveyor structures at standing height. Back and shoulder contact occurs when operators turn away from the robot.

Arms and Hands (3.1–3.3) Spring constants: 30–75 N/mm. Hands and fingers (75 N/mm) are the most frequently contacted body region in cobot applications. Operators reach into cells, handle workpieces near the robot, and interact with shared fixtures. Start compliance testing here in most installations.

Legs and Feet (4.1–4.3) Spring constants: 50–75 N/mm. Relevant for low-mounted robots, seated workstations, mobile robot bases, and automated guided vehicles. Increasingly important as mobile cobots become common in logistics and manufacturing, but often missing from risk assessments for fixed-cell installations.

Teal = Non-negotiable

Head and Neck (Regions 1.1–1.4)

The range from 10 N/mm (larynx) to 150 N/mm (skull) represents the widest variation in any body group. That variation reflects real biomechanical differences: bone versus soft tissue, rigid structures versus highly vulnerable anatomical areas. 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. 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 2.1–2.5)

All five 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 (2.2) and belly (2.3) 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 (2.1) contact appears in layouts where operators face away from the robot during part loading.

Arms and Hands (Regions 3.1–3.3)

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 lower arm and wrist (40 N/mm) appear in the same scenarios. Upper arm and elbow (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 and Feet (Regions 4.1–4.3)

The leg group runs from 50 to 75 N/mm: stiffer than the torso, similar to the hand and face regions. These body regions matter most for low-mounted cobots, robots operating below worktable height, mobile platforms, and AGVs. 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 should include the full group.

How to Use This Table

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

Body Region Mapping to Compliance Testing

1 step

Risk Assessment Complete the risk assessment for the cobot installation per ISO 12100. Identify all contact scenarios: where the robot path intersects the operator's reachable space. This is the scope for everything downstream.
2 step

Body Region Mapping Map each contact scenario to a body region from this table. One contact scenario can involve multiple regions depending on operator posture and robot path. Document the code (e.g., 3.3 for hand) and spring constant for each.
3 step

Equipment Selection Select the force transducer matching the spring constant of each body region being tested. A 75 N/mm transducer for hands, a 25 N/mm transducer for chest, and so on. The transducer spring constant must match the region being simulated.
4 step

Force and Pressure Measurement Run the robot at its actual programmed speed with the real end-effector and payload. Measure peak transient force (impact) and quasi-static force (clamping) for each contact scenario. Pressure must also be measured separately.
5 step

Comparison Against Limits Compare measured values against the force and pressure limits from ISO/TS 15066 or ISO 10218-2:2025 for each body region and contact type. Flag any exceedances for corrective action.
6 step

Documentation Record body region codes, spring constants used, transducer calibration references, measured force and pressure values, and the robot program version tested. The compliance package should be reproducible by an auditor.

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

CoboSafe Transducer Selection by Body Region

CBSF-150 CBSF-75 CBSF-60 CBSF-50 CBSF-40 CBSF-35 CBSF-30 CBSF-25 CBSF-15 CBSF-10 Spring constant (N/mm) 150 75 60 50 40 35 30 25 15 10 Body regions covered 1.1 Skull 1.2 Face, 3.3 Hand, 4.3 Feet 4.2 Lower Leg 1.3 Neck sides, 4.1 Thigh/Knee 3.2 Lower Arm/Wrist 2.1 Back/Shoulders 3.1 Upper Arm/Elbow 2.2 Chest, 2.4 Pelvis 2.5 Buttocks 1.4 Larynx, 2.3 Belly

CoboSafe covers all 15 body region spring constants across 9 transducers. Some transducers serve multiple regions that share the same spring constant (face and hand at 75 N/mm, for example). 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

Why do different body regions have different force limits?

Each body region has different mechanical properties. The skull (150 N/mm) is rigid and absorbs little energy on impact, while the abdomen (10 N/mm) is soft and compliant. The spring constant determines how force is transmitted through tissue, which directly affects injury risk at a given impact force.

Which body region should I test first?

Start with the body regions most likely to be contacted based on your risk assessment. In most cobot applications, hands and fingers (75 N/mm) are the first contact point. If operators reach into the cell or work alongside the robot at torso height, add chest (25 N/mm) and upper arm (30 N/mm).

Do the force limits change between transient and quasi-static contact?

Yes. Transient (impact) limits are higher because the contact is brief and the body can absorb the energy. Quasi-static (clamping) limits are lower because sustained force causes more tissue damage. Both must be measured separately for each body region and contact scenario.

How do I use the spring constant for measurement?

The spring constant determines which force transducer to use during compliance testing. A measurement system like CoboSafe has individual transducers calibrated to each spring constant. You select the transducer matching the body region being tested, then measure the contact force at that point in the robot cell.

Are these values the same in ISO 10218-2:2025?

Yes. The body region data from ISO/TS 15066 Table A.2 has been incorporated into ISO 10218-2:2025 without changes to the limit values. The spring constants and body model remain the same.

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