collaborative-robot

name	collaborative-robot
description	Collaborative robot (cobot) — ISO/TS 15066 safety modes (SSM/PFL/HGP/SLS), TCP force/torque limits, power and force limiting (PFL), workspace design, UR/Fanuc/KUKA cobot specs.
metadata	{"priority":7,"promptSignals":{"phrases":["collaborative robot","cobot","ISO 15066","power force limiting","human robot collaboration","cobot safety","UR robot"],"minScore":3}}

Collaborative Robot — Complete Skill

Standards Framework

ISO 10218-1/2 (2011): industrial robots and robot systems — general safety ISO/TS 15066 (2016): robots and robotic devices — collaborative robots (supersedes TS 15066:2011) ISO 10218 revision (2022): merged and expanded coverage

OSHA applicable: 29 CFR 1910.217 (power presses); 1910 Subpart O for industrial robots ANSI/RIA R15.06: US national adoption of ISO 10218

Four Collaborative Operating Modes (ISO/TS 15066)

1. Safety-Rated Monitored Stop (SMS)

Robot stops when human enters workspace; resumes when human leaves No force/power limits required (robot is stationary during collaboration) Uses safety-rated (Category 3/PLd) stop function Response time: < 0.2 s typical

2. Hand Guiding (HGP)

Human directly guides robot with force input at TCP (teach mode) Speed limited: ≤ 250 mm/s (robot speed) Force limiting not required if robot is speed-limited and compliance device used End-effector must have force/torque sensor or gravity compensation

3. Speed and Separation Monitoring (SSM)

Robot operates at reduced speed based on distance to human d_s = (v_r + v_h) × T_r + S_tr + Z_d + C

d_s = safety distance [m] v_r = robot speed [m/s]; v_h = max human hand speed [1.6 m/s per ISO] T_r = robot stopping time [s] S_tr = position uncertainty; Z_d = detection zone uncertainty; C = intrusion depth

Safety scanner (SICK, Pepperl+Fuchs) measures human position → feeds PLC → speed scaling

4. Power and Force Limiting (PFL)

Robot continues operation; limits applied force so contact is non-injurious Primary contact limit: from biomechanical injury data (ISO/TS 15066 Annex A, Tables A.2 and A.3) Force and pressure limits per body region:

Body Region	Max Force F [N]	Max Pressure P [N/cm²]
Skull/forehead	130	49
Face	65	11
Neck (front)	145	7.8
Chest	210	25
Hand/fingers	140	30
Lower arm	160	36
Upper arm	150	32
Thigh	220	50

Quasi-static (clamping) limits: lower than transient; sustained contact more injurious Transient (impact): up to 2× quasi-static limits for < 0.5 s

Power limit: P_max = 80 W (human metabolic rate upper bound per ISO/TS 15066) At TCP: F_tcp × v_tcp ≤ 80 W

Cobot Hardware Specifications

Universal Robots (UR)

Model	Payload	Reach	TCP Force	Weight
UR3e	3 kg	500 mm	Force sensing ±50N	11.2 kg
UR5e	5 kg	850 mm	Force sensing ±150N	20.6 kg
UR10e	10 kg	1300 mm	Force sensing ±150N	33.5 kg
UR16e	16 kg	900 mm	Force sensing ±250N	33.5 kg

Built-in force/torque sensor in base (6-DOF); safety-rated joints

KUKA LBR iiwa

7-DOF; redundant kinematics; torque sensing in all joints

Model	Payload	Reach
iiwa 7 R800	7 kg	800 mm
iiwa 14 R820	14 kg	820 mm
Sensitivity: < 0.5 N, < 0.5 Nm in all joints; ISO 10218 PLe

Fanuc CRX Series

CRX-10iA: 10 kg, 1249 mm reach; tablet-based programming; green casing (collaborative mode) Green-light operation: PFL active; no additional guarding required

ABB YuMi / GoFa

YuMi (IRB 14000): 7-DOF each arm; 0.5 kg/arm; dual-arm; assembly applications GoFa (CRB 15000): 5 kg, 950 mm; extended PFL cobot

Risk Assessment (ISO 10218-2 Section 5.4)

Required steps:

1. Define collaborative workspace and tasks
2. Identify hazards (pinch, crush, sharp, speed)
3. Estimate severity and probability per ISO 12100
4. Apply protective measures in order:
   • Eliminate/substitute
   • Engineering controls (PFL, SSM, SMS, safeguards)
   • Administrative (training, PPE)
5. Validate residual risk acceptable

Validation testing:

• Measure TCP force with force plate / calibrated load cell
• Measure contact pressure with pressure measurement film (Fujifilm Prescale or FSR)
• Verify stopping time/distance under worst-case conditions

End-Effector Compliance

Rigid tools → higher impact force → may exceed PFL limits even at low speed Compliant end-effectors: spring/rubber buffers on tooling; reduces effective mass Spring compliance k: F_impact = k × v × √(m_eff/k) = √(m_eff × k) × v Reduce m_eff: tool mass critical in PFL mode; lighter end-effectors preferred

Tool mass effect: F_impact ∝ √(m_eff) for spring-contact model Every 50% reduction in end-effector mass → 29% reduction in peak impact force

Payload and Inertia

Effective payload: payload × acceleration = force reaction At max rated speed/acceleration, joint torques must stay within safety limits Run-in torque validation: teach program, verify joint torque monitor alarms don't trigger

Application Examples

Pick and place (PFL): speed < 250 mm/s near humans; force monitoring via TCP sensor Screwdriving (HGP): torque-controlled; operator guides robot to location Machine tending (SSM): full speed at machine; reduced speed when operator present at load/unload station Assembly (PFL+SSM hybrid): SSM for approach; PFL for final operation near hands

Output

Provide: collaborative mode selection (SMS/HGP/SSM/PFL), safety distance d_s formula values [m], TCP force limit [N] and pressure limit [N/cm²] by body region per ISO/TS 15066 Table A.2, power limit check [W], recommended cobot model for payload/reach, end-effector compliance requirement, risk level (PLd/PLe per ISO 13849-1), validation test procedure.