Key Takeaways of this Article:
✅ Which modes of human-robot-interaction (HRI) are available?
✅ Which robot operating speeds are allowed in which mode?
Modes of Human-Robot-Interaction (HRI)
For realizing the different levels of human-robot-interaction (coexistence, cooperation, collaboration), the ISO/TS 15066 defines four modes of human-robot-interaction, that can be used as standalone solution or in combination with each other:
- Mode 1: Safety-rated Monitored Stop (SRMS)
- Mode 2: Hand Guiding (HG)
- Mode 3: Speed and Separation Monitoring (SSM)
- Mode 4: Power and Force Limiting (PFL)
Safety-rated Monitored Stop (SRMS)
For the safety-rated monitored stop (SRMS) external safety devices, such as laser scanners or light curtains are used, to detect the presence of an operator. When the operator enters the designated interaction zone, the safety system triggers a safe stop of the robot. SSM can be used with both industrial and collaborative robots.
Robot stops when red SRMS zone is violated
Hand Guiding (HG)
With the hand guiding (HG) mode, an operator can directly guide the robot by applying forces for translation into a direct robot movement. The robot system requires some kind of sensor to measure and compute the input forces and control the manipulator to enable the desired motion. This mode is comparable to crane operation with extended degrees of freedom to manipulate heavy objects. This mode can be used for both classical industrial and collaborative robots.
Manually guiding robot to move objects in HG mode
Speed and Separation Monitoring (SSM)
The speed and separation monitoring (SSM) mode also utilizes external safety devices to detect the proximity to the operator and adjust the robot speed accordingly. When the operator approaches, the robot decelerates. As soon as the operator leaves the interaction zone, the robot accelerates again. SSM can be used in combination with SRMS & PFL modes and for both industrial and collaborative robots.
Robot adjusts operating speed when yellow SSM zone is violated
Power and Force Limiting (PFL)
For the power and force limiting (PFL) mode, robots with an additional safety-related control system are required: either collaborative, inherently safe robots or industrial robots with additional sensors directly on the manipulator, such as sensitive skins. This control system needs to limit the occurring contact forces and pressures between robot and operator according to the biomechanical threshold values defined in ISO/TS 15066. Furthermore, this standard also describes various passive and active measures.
Passive measures:
- Increase the potential collision area and reduce occurring forces
- Safety-by-design: rounded edges, no clamping areas
- Lightweight design to reduce robot mass
Active measures:
- Force & torque limitation
- Speed limitation
- Energy limitation
- Space limitation
- Integration of sensing devices: torque sensors, force/ torque sensors, motor current monitoring, sensitive skins, etc.
PFL can be used as a standalone solution or in combination with SSM and for collaborative robots or alternatively industrial robots with additional onboard safety systems.
Collaborative robot stops at the event of contact in PFL mode
References
Mensch-Roboter-Kollaboration. Aber sicher! (2016). Pilz GmbH & Co. KG.
Zaeh, M.F. (2016). Enabling manufacturing competitiveness and economic sustainability : proceedings of the 5th International Conference on Changeable, Agile, Reconfigurable and Virtual Production (CARV 2013), Munich, Germany, October 6th-9th, 2013. Cham: Springer.
Hesse, S. and Schnell, G. (2012). Sensoren für die Prozess- und Fabrikautomation. Springer-Verlag.
Gurgul, M. (2018). Industrial robots and cobots: Everything you need to know about your future co-worker. Michał Gurgul.
Liu, H. (2020). Robot systems for rail transit applications.
Matteo Fumagalli (2014). Increasing Perceptual Skills of Robots Through Proximal Force/Torque Sensors A Study for the Implementation of Active Compliance on the iCub Humanoid Robot. Cham Springer International Publishing.
Saïd Zeghloul, Med Amine Laribi, Sebastian, J. and Springerlink (Online Service (2020). Advances in Service and Industrial Robotics : Results of RAAD. Cham: Springer International Publishing, Imprint Springer.
Robotic Systems: Concepts, Methodologies, Tools, and Applications. (2020). IGI Global
ISO 10218-1: Robots and robotic devices – Safety requirements for industrial robots – Part 1: Robots. (2011). International Organization for Standardization.
ISO 10218-2: Robots and robotic devices – Safety requirements for industrial robots – Part 2: Robot systems and integration. (2011). International Organization for Standardization.
ISO/DIS 10218-2: Robotics – Safety requirements for robot systems in an industrial environment – Part 2: Robot systems, robot applications and robot cells integration. (2020). International Organization for Standardization.
ISO/TS 15066: Robots and robotic devices – Collaborative robots. (2017). International Organization for Standardization.
ISO 13855: Safety of machinery – Positioning of safeguards with respect to the approach speeds of parts of the human body. (2010). International Organization for Standardization.
IEC 60204-1: Safety of machinery – Electrical equipment of machines – Part 1: General requirements. (2016). International Electrotechnical Commission.
SICK Sensor Intelligence. (2018). Safe Robotics Area Protection: Open access for maximum productivity | SICK AG. [online] YouTube.
YASKAWA THAI (2021). YASKAWA – GP180 with Handguide Function Wheel & Seat Handling Assist Demo. [online] YouTube.
YASKAWA Europe GmbH (2023). Yaskawa MOTOMAN HC30PL Cobot – easy start into Robotic Palletizing. [online] YouTube.
