Thought Leaders in Automation

Chris Soranno | FS Exp, CFSAE-T

Safety Standards & Competence Manager
SICK

Interview Posted: June 28, 2023

Chris Soranno is a Functional Safety Expert in Machinery Safety (TÜV Rheinland) and has been dedicated to industrial safety his entire career. During this time, he has worked for manufacturers, distributors and integrators of safety components and systems. Chris has experience working with equipment suppliers, integrators and users in diverse global applications.

As the Safety Standards and Competence Manager for the SICK organization, Chris is responsible for regional and global safety competency and directing safety standardization work for the Americas.

Chris is an active member of numerous standards committees in North America, including industrial robot standards RIA R15.06, CSA Z434 and UL 1740, as well as vice chair of the industrial mobile robot standard RIA R15.08. Chris has been a long time contributor to SPI B151 standards for the plastics industry and ASSE Z244 for control of hazardous energy, as well as a member of many B11 subcommittees for machinery safety. He is the chairperson of ANSI B11.19 (performance criteria for risk reduction measures) and ANSI B11.20 (integrating machinery into a system). Internationally, he is also a member of ISO technical committees for robotics, industrial trucks, plastics and rubber machines, metal forming machines, and safety of machinery – including project leader for the ongoing revision of ISO 11161 for integrated manufacturing systems as well as the new project ISO 12895 addressing whole body access..

QUESTION

What questions should companies be asking to ensure their employees are safe around robot equipment?

ANSWER

It is important that an application-specific risk assessment has been performed on the deployed robotic system.  Not only is this a requirement of the current standard and industry best practice, but it is a practical methodology to identify risks – most typically comprised of task/hazard pairs – and then selecting appropriate risk reduction measures based on the associated task and related hazardous conditions.  For companies that have not yet conducted a documented risk assessment, they can simply talk to operators in industrial environment and ask which tasks make them feel most uncomfortable to perform.  This ‘gut feeling’ is our natural response to risk; a so called ‘real-time’ risk assessment.

In addition, companies should be aware of any changes or modifications made to their robotic systems.  Even with a thorough risk assessment performed at the deployment of the cell, subsequent changes (components, processes, materials, sequences, etc.) may have altered the risk profile, and/or the previous risk reduction measures may no longer be adequate for the application.  A good change-management system goes hand-in-hand with a detailed risk assessment to achieve acceptable residual risk.  If modifications have occurred, a review or update of the previous risk assessment is a great place to start, along with a periodic inspection of the existing risk reduction measures.

QUESTION

What are the requirements to ensure robot safety standards are being met?

ANSWER

Subject matter expertise is essential to meeting current industry safety standards.  Often, companies have heard of a standard, but have never actually seen it.  It’s nearly impossible to comply with a standard that never been read, so the first step is identifying the relevant standards – and there will most definitely be more than a few that apply – and obtaining them.  Having these standards in hand will form the foundation for understanding and applying the relevant requirements.  Increasing competence is also important (such as through industry seminars or external training programs), but none of these are a direct replacement for actually reading the requirements of the standards.  From this foundation, organizational elements need to be in place to emphasize the important of equipment safety and budget accordingly.

QUESTION

What types of additional equipment needs to be purchased when purchasing a robot or robot system to ensure safe practices?

ANSWER

There is still a common misunderstanding that newer robots with collaborative functionality do not require safeguarding.  In fact, this could not be further from the truth.  While the vision of “fenceless robots” can be a reality, this cannot be mistaken for “robots without safeguarding”.  Collaborative robot applications which use safety features such as speed and separation monitoring (SSM) require reliable detection of the operator in the workspace, coupled with reliable communication to the robot, to achieve an adequate speed based on the separation of the person from the hazard zone.  This separation distance can be dynamic, reducing in real-time commensurate to the robot speed, but other industry norms still apply to determine the sufficient distance.  Furthermore, collaborative robot applications which rely upon power and force limiting (PFL) to reduce risk also have requirements for additional protective devices (e.g., safety sensors) to monitor the position / location of exposed personnel in the area of the collaborative workspace.  Measures must also be in place to either prevent (with guards) or detect (with sensors) when an operator passes beyond the collaborative workspace into the hazard zone.  This common misnomer of a “safe robot” is still a surprise to some end users when these additional requirements must be factored in to the final application design.

QUESTION

What are some of the most important factors to consider when designing a safety system for a robotic application, and how can companies ensure that their safety systems are effective in preventing accidents?

ANSWER

The overall reliability of the safety system is a key element in preventing accidents.  This reliability, now more commonly referred to as “functional safety”, is a deterministic evaluation of the safety system – from input, to the logic system, and on the equipment under control.  The current robot safety standards requires that all functional safety systems of a robot system meet Performance Level d (PL=d) with a circuit structure category 3 as described in ISO 13849-1 –unless, of course, a comprehensive risk assessment determines that a difference PL and category are appropriate.

In addition, the correct application of the selected risk reduction measures (RRMs) is also important.  Having a reliable control system which still allows a person to access the hazard undetected is ineffective.  Therefore, the RRMs selected must be designed and applied in accordance with other industry standards.  For instance, a simple fence must be dimensioned to prevent reaching over, under or around to the hazard zone, and the material must also prevent reaching through the fence.  When the size or material cannot be modified, then additional distance must be provided to prevent access to the hazard zone.  The same applies for various protective devices (light curtains, laser scanners, interlocking guards, etc.) where some amount of intrusion is required before reliable detection of the person.  In these cases, the overall stopping performance of the system must be determined – either through calculation or measurement – to determine the appropriate distance of the protective device (and the relevant detection zone) from the hazard(s).

QUESTION

With the increasing use of collaborative robots in industrial settings, what are some of the unique safety challenges that arise when working with these types of robots, and how can they be addressed?

ANSWER

As mentioned earlier, collaborative robot applications which rely upon SSM must account for each state of operator and robot location/speed.  The dynamic changes which occur must be accounted for, and the appropriate logic and switching cases (for both the speed and the sensor detection zone) must be validated.  With PFL applications, there are added challenges which must be addressed.  The robot safety standard requires that the foreseeable contact situations between the robot system and the person must be identified.  These contact situations include the type of contact (either quasi-static or transient), as well as which body regions of the operator are exposed to contact.  This issue then become more critical when sensitive body regions (skull, face, and neck) may be impacted by the industrial robot system.  Strategical combination and interpretation of various standards can be used to determine the contact situations, and novel design approaches can be applied to reduce the likelihood of some contacts.  However, since the likelihood of contact can often not be eliminated, new technologies are becoming available to help detect when sensitive body regions may be approaching unacceptable contact situations.

QUESTION

How do you think universities and other educational institutions can better prepare the next generation of engineers and technicians to work safely with robots and other advanced automation technologies in industrial settings?

ANSWER

Very few educational institutes are currently introducing tomorrow’s engineers and designers to the world of safety standards.  All too often, newly-minted engineers first hear about a safety standard by word-of-mouth or – unfortunately – after an incident or a near miss event.  Not only are industry consensus standards a new concept to most recent graduates, but they then find out that these standards continue to evolve and are frequently updated – meaning it’s a moving target.  This emphasizes the importance of continuing education to ensure staying abreast of latest trends, technologies and best practices necessary to provide state-of-the-art solutions to create safe work environments.