Considerations in collaborative robot system designs and safeguarding.
Applications using industrial robotics have typically led to establishing a safeguarded space encompassing a wide radius around the robot. Operator access to this hazard zone was restricted by a combination of means, such as hard guarding, safeguarding, awareness means, and personal protective equipment. The introduction of collaborative robots is redefining safeguarding requirements. Many collaborative robots have inherently safe designs that enable an operator and a robot to work within a shared, collaborative workspace.
New technology in industrial robotics has opened up opportunities for collaborative operation. Collaborative operation could include either industrial or collaborative robots, depending on its application. The current defined modes of collaborative operation are hand guiding; speed and separation monitoring; safety-rated monitored stop; and, power and force limiting.
Collaborative robots and collaborative operations change what safeguarding will be required and how the system will be designed. Industry needs will continue to push this technology to include higher speeds and more capability while finding new ways to make the interaction between the collaborative robot and operator smarter and safer.
CITATION: Hull, T. and Minarcin, M., "Considerations in Collaborative Robot System Designs and Safeguarding," SAE Int. J. Mater. Manf. 9(3):2016, doi:10.4271/2016-01-0340.
The safety standards for industrial robots have been developed over many years and are based on best practices gleaned from user experience and lessons-learned following workplace accidents. Implementing requirements for safeguarding have kept accident rates low, primarily by keeping operators away from the hazards.
Collaborative operation allows operators to be close to the collaborative robot under conditions in which contact might otherwise occur. While industrial robot safety standards may not be practical for collaborative operations, safeguarding may be needed to protect the operator when limits are outside the acceptable range. The primary goal of any automation system is to achieve a high level of productivity while keeping the operator safe . The challenge is to use existing knowledge as a basis for understanding and better defining new limits for an emerging technology that changes how humans interact with collaborative robot systems.
The operator has primary responsibility for system safety, according to standards ANSI RIA R15.06-2012  and ISO 11161 2007 . The operator is defined as any person given the task of installing, using, adjusting, maintaining, cleaning, repairing, or transporting machinery [2,3].
Note: Many ANSI standards define the operator role using descriptors such as individual, operator, installer, personnel, integrator, and supplier [2,4].
Studies in Sweden and Japan indicate many robot accidents do not occur during normal operation, but rather when operators are performing installations, maintenance, and adjustments . These accidents often are caused by unpredictable speed and motion events triggered by sensor motion unintentionally power activation, or programming-sequence error.
A known hazard with industrial robots is singularity as shown in Figure 1, when the joint velocity (in joint space) can become infinite to maintain Cartesian velocity, thus producing high axis speeds . This erratic function during programming use may lead to injury. Many potential injuries have been reduced by new requirements in the standards to either stop the robot and provide a warning before this occurs, limit the maximum speed and provide a warning, or to control it without creating a hazardous motion.
A risk assessment is required for all industrial and collaborative robot applications [6,7]. The integrator conducts the risk assessment, with the end-user participating. It should be a group task including operators and safety experts. During collaborative operations, special consideration should be made for tasks where contact between the collaborative robot and the operator is possible.
ISO 12100 2010 defines hazard zone as any space within or around machinery in which a person can be exposed to danger . Sources of hazards include, but are not limited to, human errors, control errors, unauthorized access, mechanical failures, environmental sources, power systems, and improper installation and design.
The hazard zone for an industrial robot system includes the robot, end-effector, workpiece, and any device activated from the robot's control system . Hazards arise from operational characteristics, including high-energy movement through a large operational space, movement and varying paths being difficult to predict, and overlapping operating space with other robots and machines. Because of these hazards, a restricted space is calculated and used to define a safeguarded space that restricts operators from entering the hazard zone.
Collaborative robots used in a collaborative operation are designed for operators to work in close proximity. The operating space is defined as the area where the operator may not enter while the collaborative robot is in motion . The space within the operating space where the robot (including end-effector, workpiece, and fixture) and the operator can perform tasks concurrently is known as the collaborative workspace .
Hazard Identification and Safeguarding
With industrial robot applications, few human factors are considered since correctly designed and implemented protective devices stop hazardous motion before the operator reaches the robot . Protective devices - such as safety-rated light curtains, area scanners, electro-mechanical switches, non-contact switches, mats, edges, bumpers, 3-D vision systems, sensors, and two-hand controls - monitor the operator's action and initiate stop commands when necessary. Hard guarding, such as fencing, is commonly used for areas where access is not needed and as a supplement for the safeguarding.
In collaborative robot applications, human factors are more likely to lead to contact since the operator is in close proximity to the collaborative robot, end-effector, work-piece, and fixture. The type, location, and force of the contact are important criteria when designing a system and keeping limits below acceptable threshold values. The difference between quasi-static and transient contact can affect the duration of the exposure and the ability to retreat away from the hazard . The threshold of pain varies for different regions on the body and can affect operator location and movement . The operator's neck and head are considered critical areas and not allowed to have any contact with a collaborative robot .
System design should consider the operator's physical and mental limits, such as stress, fatigue, and ergonomics, common errors, reflexes, training, skill levels, and time limit constraints. In some cases, safeguarding with devices such as the safety-rated area scanner or 3-D vision system may be needed to detect deviations or additional personnel . A SQL database could track production rate and indicate when productions falls below a limit, as a way to indicate human fatigue or potential issues with the system . Tracking how often the reset and restart pushbutton is activated could indicate issue trends since this action is usually required for collaborative robot applications only when an abnormal condition has caused a stop.
Hazard Identification Unique for Collaborative Operation
The primary new hazard for collaborative operation is contact between the operator and the collaborative robot, its end-effector, fixture, and the workpiece . Applications that involve tooling or work pieces with sharp edges or extruding pieces; systems that can create a spark and require shielding (such as arc flash from welding); anything with extreme temperatures capable of causing frostbite or severe burns; and, hazardous characteristics such was water-jet or laser cutting should be evaluated for inherent hazards and additional levels of guarding to reduce the risk of operator exposure.
The design should consider and account for impact on the operator if the collaborative robot loses its workpiece. The design also should address operator motion (approach and exit locations, extended reach, picking up dropped parts); speed and impact from clamping fixtures; personal protective equipment interference; operator's ability to retract upon contact; and, impact based upon robot, operator, and surrounding fixtures.
With industrial robot applications, safeguarding is designed to detect and prevent all hazardous motion if an operator entered the safeguarded space . Even so, other drive-power hazards can still exist even if the robot is not moving. In some cases, different levels of drive power, such as teach or auto mode, could have different levels of hazard. While a collaborative robot is designed to be inherently safe , additional equipment within the system may not have the same performance level or safe design. A risk assessment should indicate if additional safeguarding is needed.
While a collaborative robot is inherently safe by design, the operator's tasks impact the overall design of the system. One thing to consider is how long the operator is in the collaborative space since time can affect the frequency and duration of contact between the operator and the collaborative robot. A minor injury sustained by a single, short contact could become more serious if it is repeated frequently or if the time is extended.
The transition into the collaborative space is a factor when it requires the collaborative robot to slow its speed or stop before the operator enters. It may also affect what end-effector and fixturing may actuate when the operator is present. System applications such as clamping, part release, and fluid dispensing may create hazards. When and how the collaborative robot may resume faster speed or perform tasks not permitted when the operator is not present should also be determined. The system may need different safeguarding if the tasks require multiple operators within the collaborative workspace or when additional procedures may affect the operator's location, reachability, or stamina.
In most collaborative applications, the robot has to know when the operator is within the safeguarded or collaborative space. This detection often is achieved with safety-rated presence sensing devices such as light curtains, safety mats, and area scanners.
Many designers prefer an area scanner for its ability to slow down motion in the space as the operator approaches. A gradual slowdown may increase the life of the robot by reducing wear and tear. An industrial robot application requires a category 0 stop when an operator enters the safeguarded space . Note that a category 1 stop is allowed when it is a time-delayed stop that will lead to a category 0 stop . A collaborative robot application may maintain its power in a category 2 stop, thus allowing for an automatic restart, which could increase cycle time .
A common use for collaborative robots is the ability to quickly reconfigure a system, making it a solution for applications with short lifecycles . The area scanner zones are typically easier to reconfigure with software compared to hardware adjustments required for other presence-sensing devices.
Risk reduction in industrial robot systems is primarily achieved through safeguarding. With collaborative applications, risk reductions usually are achieved through the collaborative robot's inherently safe design features such as a seven degree of freedom manipulator, force sensing, compliant mode, low-inertia servo motors, elastic actuators, collision detection, safety-rated axis limits, and redundant encoders .
Industrial and collaborative robots have different risk reduction requirements. With an industrial robot, for example, the safety area scanner could be used to slow down the robot speed as the operator approaches the hazard, and then send a signal to stop the robot when the operator enters the safeguarded space. In a collaborative robot application, the same scanner could slow down the robot, but the slow down speed may be different since the robot may continue to move when the operator enters the collaborative space. The collaborative robot only stops if the operator enters the operational space. In many cases, the operational space would allow the collaborative robot to operate at speeds higher than the allowed limits based on the relationship between transferred energy and robot speed during transient contact or perform hazardous tasks when the operator is not present.
Without safety-rated presence sensing devices, an operator may not be aware of a system's activated power status. Indicator lamps or warning signals should be considered when unexpected motion could cause a hazard.
There are two types of stops, emergency stop and protective stop, and each one is active for different reasons [6,14]. The machine directive clearly states systems shall have an emergency stop. The only exception to requiring an emergency stop is when it does not provide additional safety .
For industrial robot system, common emergency stop requirements are that it has to be continuously operable, readily accessible, manually initiated, capable of overriding all other functions, and maintained once activated. In most application this is achieved with a red mushroom-shaped pushbutton with a yellow background. For systems with a longer span of control, it may also be achieved with an emergency stop pull-rope .
Having an emergency stop pushbutton on the collaborative robot may impede its functionality and not provide additional protection. Many collaborative robots are designed to perform the emergency stop function by a force pushing on the collaborative robot, and their controls are by an internal safety rated circuit. The risk assessment would indicate if additional emergency stop devices are needed based on unique applications or due to other machinery within the system.
Any detected failure in the safety-related parts of the control triggers a protective stop. With industrial robots the protective stop is initiated by safeguarding devices. Unlike emergency stops, which are initiated by the operator to immediately shut down the whole system, protective stops may shut down zones while allowing hazardous motion that could put the operator risk.
The protective stop may be initiated by safeguarding devices for a collaborative robot, or the collaborative robot may be equipped with a category 2 safety-rated monitored stop function .
Applications utilizing industrial robotics have typically led to establishing a safeguarded space that encompasses a wide radius around the industrial robot. This area includes machinery associated with the system's process, end-effector, work piece, fixtures, or machinery controlled by the industrial robot. The total area could be reduced when the design prevented operator access to the hazard at all times . An example would be placing the robot close to a wall or adding hard guarding with spacing too small for an operator to access. Operator presence is not permitted within the hazardous zone. Access is limited by a combination of means, which may include hard guarding, safeguarding, awareness means, and personal protective equipment. The safeguarded space is defined by a calculation based on the hazard zone, the stopping time of the machine, and a safe distance . Since most industrial robot operate at a high speed, the area required to achieve the safeguarded space can require a significant amount of floor space or restrict the type of safety devices used in the application.
Some access is allowed under restricted conditions, such as a teach mode that keeps the robot at a low speed as long as an enable switch is activated by every operator within the safeguarded space .
A common factor for industrial and collaborative robot operational space calculations is the tool center point and the workpiece dimension, since they add to the robot's overall operational space. When multiple tool center points or workpieces are used, maximum values are typically used for the design.
The introduction of collaborative robots redefines safeguarding requirements. Many collaborative robots have inherently safe designs, which according to ISO 12100-1 2010 is defined as "measures taken to eliminate hazards and/or to reduce risks by changing the design or operating characteristics or product or system" . Collaborative robots may be designed to sense when operators are in its operating space. They may be designed to adjust their own behavior, such as reducing their speed, to minimize potential injury when contact with an operator is possible. These designs enable application where the operator and collaborative robot may work within a shared, collaborative workspace.
While the collaborative robot may be inherently safe, hazards may still exist within the rest of the system. The operator does not have access to tooling and fixturing with industrial robot applications since they are contained within the safeguarded space. In collaborative operations, the operator may have access to these devices during their operation, which creates new design and risk considerations.
An example of how the tooling and workpiece design differs between an industrial and collaborative robot system would be a workpiece with sharp edges. Sharp edges would not be considered a high risk for an industrial robot when the workpiece is contained, placed away from operator access, or held at a standstill if an operator enters the safeguarded space during tasks such as maintenance. If the robot lost the part during operation, the safeguarding should be designed with hard guarding capable of containing the workpiece within the safeguarded space.
With a collaborative system, the operator may have more exposure to the sharp edges and the exposure also exits while the workpiece is in motion. If there is a failure with the end-effector, which leads to an uncontrolled loss of the workpiece, there could be the potential of the workpiece being projected toward the operator. Different design factors may be necessary to reduce the possibility of a injury, such as placing the robot so any uncontrolled loss would be away from the operator, reducing speed, or using workpieces that are lightweight and have rounded corners.
ISO TS 10566 2015 (draft version) defines collaborative workspace as the space within the operating space where the robot system (including the work piece) and a human can perform tasks concurrently during production operation .
While the industrial robot safeguarding keeps the operator away from hazards associated with the end effector and workpiece, collaborative robot applications may expose the operator to these hazards. New considerations may include injury from device actuation, entanglement from cables, bruises from extruding pieces, cuts from sharp edges, and crushing due to entrapment with surrounding structures.
The collaborative workspace may also be a limited area of the operating space. Any operating space outside the collaborative workspace requires safeguarding.
One feature is the collaborative robot's flexibility to be set up quickly for applications with small production lots . This may lead to conditions where it is more advantageous to have the operator take the place of the collaborative robot and complete a few unplanned tasks. Or, if the robot needs to be shut down, an operator could step in and temporarily perform the collaborative robot's task. The placement of the collaborative robot may change the design layout to accommodate these options, other machinery, and additional hazards such as crushing between the collaborative robot and other machinery.
TYPES OF COLLABORATIVE OPERATION
Collaborative operation is a state in which a purposely-designed robot system and an operator work within a collaborative workspace . Collaborative operation may not always include a collaborative robot with inherently safe design features always activated.
Industrial robots have been used in hand guiding applications for many years. While the industrial robot is not purposely designed for a collaborative operation, the additional safeguarding design makes it suitable to be used in the application. A collaborative robot, which is designed specifically for collaborative operation, also can be used in a hand-guiding application, but its safeguarding requirements may vary.
Other collaborative operation applications may only be used with a purposely-designed robot system, such as a collaborative robot.
In this application, the robot gives up partial control while power is still on so operator can manually adjust its position  as shown in Figure 2. Hand guiding is primarily used to teach or reteach robot positions. It has been used with traditional robots when the robot is in teach/task programming mode, giving the operator control and the ability to maintain safe operation.
With an industrial robot, the robot is typically not allowed to move when the operator enters the collaborative workspace. A safety rated area scanner may be used to monitor the safeguarded space and ensure a safe distance is maintained. And the operator may need to switch to a teach zone before entering the safeguarded space.
If the operator prematurely enters the space, the safety-rated control system, which is generally an external system, generates a protective stop. The operator needs to clear the system before it can engage the hand-guiding application.
Many industrial robots have higher payloads and speeds. To maintain control and stop the system before an injury can occur, the use of hand guiding in these applications require a guiding device equipped with an enabling device and an emergency stop. The hand guiding application is activated when the operator actuates an enabling device, which is typically located close to the end-effector. The operator also needs the ability to activate an emergency stop, which is typically part of the design of a three-position-enabling device. The emergency stop is located close to the end effector so the operator can use it without causing additional hazards and while having a clear view of the entire the area. In this case the entire workspace is the collaborative workspace.
A collaborative robot used in the same application may not require the enabling device as long as the collaborative robot's inherently safe design measures or safety-rated limiting functions meet the same requirements as the industrial robot's application using the enable switch and emergency stop and the features remain active. Risk reduction for the operator may be internally designed into the collaborative robot since it is designed to stop when contact is made.
The training program should include safe procedures for this application since the operator is responsible for preventing a crushing hazard . The motion and direction should also be intuitive to the operator. For example, moving a robot to the left manually to teach the program point should operate in the same way when in programming mode.
Hand-guiding transition has to be a deliberative and controlled behavior. It cannot lead to unexpected motion or create additional hazards. The robot speed should be reduced to a maximum of 250 millimeters per second-although the risk assessment might indicate a higher speed would be acceptable as long as the operator can maintain control of the robot . The robot must not have uncontrolled singularity.
Safety-Rated Monitored Stop
In this application, a collaborative robot equipped with the safety-rated monitored stop function issues a protective stop before the operator enters the collaborative workspace .
Note: Most suppliers that provide the safety-rated monitored stop will also provide the safety-rated soft axis and space-limiting functions. Productive applications will often involve the use of the safety-rated monitored stop and the safety-rated space limiting functions.
The collaborative robot must not enter the collaborative workspace when the operator is present as shown in Figure 3. A safe distance needs to be defined and safeguarding is required to stop the robot if the operator enters the restricted space.
The robot system needs to know when the operator is within the safe distance of the collaborative workspace, which is done with safety-rated devices such as area scanners or mats for open areas, or light curtains and sensors if the safeguarding also incorporates methods so the operator can only enter and exit the hazard zones through the light curtain. This approach may also require a manual reset to confirm the area is clear.
Speed and Separation
Speed and separation applications use a protective-separation distance to control the distance between the safety-rated monitored speed, the stop-enabled robot, and the operator .
In these applications, it is important to understand how the collaborative robot will stop if the operator's distance becomes too close. Ideally, the collaborative robot and the operator would continually move in the same direction and at the same rate. When the speed and direction vary, however, the rate at which they differ needs to be adjusted to maintain a safe distance. For example, the operator could be moving away from the robot and then quickly turn around and approach the robot. The robot requires time to receive the signal and time to stop. The robot's speed also may be changing based on the current separation distance. Then if the operator suddenly stops or reverses direction, the robot could speed up. The robot could even stop and the operator could continue moving toward the robot.
One way to adapt to these conditions is to monitor the robot and operator's speed and location continually while using advanced calculations to adjust the robot's speed so it never gets closer to the operator than the specified separation distance. If robot's speed is not being monitored, the integral of the robot's stopping distance that reduces the separation distances the most should be used.
The robot's range of motion could be limited by using safety-rated soft axis features or external safety-rated sensors. By using a safety rated area scanner, zones could be used instead of monitoring as shown in Figure 4. The robot's speed could be set to a constant with the command to be either on when the separation distance is established or off when it is violated. In this case, the maximum speed allowed would be based on the worst-case scenario for the entire application.
POWER AND FORCE LIMITING
In power and force limiting applications, a robot specifically designed for this type of application is required . The most common references for this type of robot are collaborative or inherently-safe. Common features include but are not limited to safety-rated monitored stop, safety-rated monitored speed, safety-rated axis limits, force sensing, collision detection, and compliance mode. Since contact can occur, these robots are usually designed with round and smooth edges, larger contact areas, minimal openings and indentations, concealed cabling, and reduced pinch points. The robot and the operator may share the collaborative workspace at any time, completing various tasks, and the area may encompass the robot's entire workspace as shown in Figure 5.
One notion about this application is that safeguarding is no longer needed since the robot will detect contact and shut down. While this may be true for the collaborative robot, it may not necessarily true for the rest of the machinery used in the application. One commonly overlooked element is the conveyor system bringing parts into and out of the collaborative workspace. In-running nip points, which can cause pinch points, associated with unprotected gears, rollers belt drives, and pulleys can result in injuries due to entanglement. Based on the risk assessment, emergency stop pull ropes may be a solution to give the operator the ability to shut down the system if the entanglement potential exists. Additional risk-reduction measures may be needed for other auxiliary machinery . Hard guarding, such as fences, may not provide optimal safeguarding solutions since the operator needs to have a way to leave the collaborative workspace. The most common safeguarding device is a safety area scanner.
Since the operator has constant access to the robot's workspace, another new focus is on the end-effectors, workpieces, and fixtures. They need to be designed so they do not pose a hazard for the operator. Design concepts being used include, but are not limited to, rounded edges and corners, smooth surfaces, compliant surfaces, padding, cushioning, compliant joints, deformable components, and protective housing and covers.
Quasi-static and transient are the types of robot to operator contact. These can affect hazards and the risk-reduction measures used when designing the system. With quasi-static contact the robot can apply pressure for an extended amount of time, such as with clamping devices. Minimizing the force, increasing surface area, using padding, and designing the system so the operator can escape independently could be part of the design. With transient contact there is a short duration of contact and the operator is able to retract away from the collaborative robot. Surrounding barriers would need to be evaluated to make sure the operator does not retract away from the robot and into another hazardous situation. Scenarios may occur where quasi-static and transient contact exists simultaneously. For instance, a fixture with a clamping element may be designed to release if the force on the clamped object exceeds the expected threshold (detecting finger or hand), yet when the operator retracts the support structure the fixture could cause entrapment. The fixture design might need to be repositioned so the support structure is away from the operator's potential path during retracting or is capable of collapsing and creating an escape route upon impact.
With transient contact, the amount of energy transfer is based on the contact force and pressure, area of contact, and the spring constant. Annex A of ISO TR 15066 has a graphical representation of the speed limits versus effective robot mass [6,11]. This graph could be used to determine the maximum robot allowable speed based on the body part or parts the robot could come into contact with.
In force and power limiting applications, the risk reduction measures rely heavily upon the inherently safe design of the collaborative robot. In speed and separation and safety-rated monitored stop applications, the inherently safe design of the collaborative robot may be part of the risk reduction measures. But in many other applications, additional safeguarding may still need to be used. Safeguarding may vary for hand guiding applications based on the type of robot used.
Collaborative operations shifts the risk reduction methods from keeping the operator away from the industrial robot hazardous zone to more focus on individual hazards within the collaborative workspace. With collaborative operations, the application can be a hazard and may require additional risk reduction methods. Regardless of the robot type, a risk assessment is needed and properly safeguarding the entire system is necessary.
Collaborative robots have smaller payloads to reduce momentum and thus the force exerted on the operator during contact. Robot speeds are greatly reduced during collaborative operation depending on the potential contact areas. It is only permitted to operate at a higher speed once the operator has left the area. With more experience and increased knowledge, the industry should be able to find ways to increase the collaborative robot's capability in a safe manner for the operator. In the future, development may lead to methods to predict operator movement and to change the collaborative robot's path. Tracking how and when the safeguarding is accessed and operated may lead to new developments for more preventative maintenance methods to reduce future faults and layout design to account for multiple uncommon operator factors.
[1.] Shikany, A, "Collaborative Robots End User Industry Insights," Robotics Industries Association, Oct. 2014 http://www.robotics.org/userassets/riauploads/file/RIA_Collaborative_Robots_White_Paper_October_2014.pdf, accessed Oct. 2015.
[2.] American National Standard for Industrial Robots and Robot Systems, "Safety Requirements," ANSI/RIA R15.06-2012.
[3.] International Organization for Standardization "Safety of machinery--Integrated manufacturing systems--Basic requirements," ISO 11161:2007.
[4.] American National Standards Institute, "Safety of Machinery; General Requirements & Risk Assessment," ANSI B11.0-2015.
[5.] Anandan, T. M., "The End of Separation: Man and Robot as Collaborative Coworkers on the Factory Floor," June 2013 http://www.robotics.org/content-detail.cfm/Industrial-Robotics-Industry-Insights/The-End-of-Separation-Man-and-Robot-as-Collaborative-Coworkerson-the-Factory-Floor/content_id/4140, accessed Oct. 2015.
[6.] International Organization for Standardization, "Robots and robotics devices - Safety requirements - Collaborative robots," ISO/TS 15066, Draft Document, Rev. Jan. 2016.
[7.] International Organization for Standardization, "Robots and robotic devices - Safety requirements - Parts 1 and 2," ISO 10218:2011.
[8.] International Organization for Standardization, "Safety of machinery - General principles for design - Risk assessment and risk reduction," ISO 12100:2010.
[9.] Occupational Safety and Health Administration, "OSHA Technical Manual Industrial Robots and Robot System Safety," Section IV, Chapter 4, https://www.osha.gov/dts/osta/otm/otm_iv/otm_iv_4.html, accessed Oct. 2015.
[10.] Occupational Safety and Health Administration, "Safeguarding Equipment and Protecting Employees from Amputations," OSHA 3170-02R 2007.
[11.] Institute for Occupational, Social and Environmental Medicine at the Johannes Gutenberg University of Mainz, "Research Project No. FP-0317: Collaborative robots - Investigation of pain sensibility at the Man-Machine-Interface," Final Report, Nov. 2014.
[12.] Omron Corporation, "Safety," https://industrial.omron.us/en/products/catalogue/safety/programmable_safety_system/programmable_safety_system.html, accessed Nov. 2015.
[13.] Omron Corporation, "NJ Machine Automation Controller with SQL Client Functionality," https://industrial.omron.us/en/products/catalogue/automation_systems/machine_automation_controllers/nj-series/nj5_database_connection/default.html, accessed Nov. 2015.
[14.] European Commission, Directive 2006/42/EC, Jun. 2006, http://ec.europa.eu/growth/single-market/european-standards/harmonised-standards/machinery/index_en.htm, accessed Oct. 2015.
[15.] National Fire Protection Association, "Electrical Standard for Industrial Machinery," NFPA 79:2015.
[16.] International Organization for Standardization, "Safety of machinery - Safety-related parts of control systems - Part 1: General principles for design," ISO 13849-1:2006.
Work phone: (847) 285-7267
ANSI - American National Standards Institute
ISO - International Standards Organization
OSHA - Occupational Safety and Health Organization
RIA - Robotics Industries Association
SQL - Structured Query Language
TS - Technical Specification
Tina Hull and Monika A. Minarcin Omron Automation and Safety
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|Author:||Hull, Tina; Minarcin, Monika A.|
|Publication:||SAE International Journal of Materials and Manufacturing|
|Date:||Aug 1, 2016|
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