What Does Robot Safety Include?

Robots can move tools and workpieces at high speed, over a large operating range, and with considerable force. Depending on the application, employees may be exposed to crushing, impact, trapping, cutting, or unexpected-startup hazards.

Robotics safety is therefore not based on a single sensor or emergency stop. It is a coordinated system designed to detect access to a hazardous area, evaluate safety signals, and bring the robot application into an appropriate safe state.

Depending on the identified hazard, the required response may be to reduce robot speed, restrict motion, initiate a safety-rated stop, prevent unexpected restart, or remove torque from the drives.

A complete safety function usually includes three levels:

These elements must be selected, connected, and validated as one safety function. A certified scanner or interlock does not make the complete robot cell safe by itself.

Why Is a Safety-Rated Component Not Enough?

A safety component may have a defined Performance Level, SIL capability, or third-party certification. These values apply to the component under specified conditions. The safety of the complete robot application depends on how all components, hazards, and operating modes interact.

The assessment should include more than the robot itself. Relevant factors include:

• the end effector and tooling,

• handled or processed workpieces,

• robot speed and operating range,

• accessible crushing and trapping points,

• surrounding machines and conveyors,

• loading and unloading areas,

• setup, maintenance, and troubleshooting,

• control software and possible restart conditions.

A collaborative robot may include safety-rated force, speed, and position functions. However, a sharp workpiece, heavy gripper, hazardous process, or accessible pinch point can still make additional safeguards necessary.

The correct question is therefore not:

“Is the robot safe?”

It is:

“Is the complete application acceptably safe for every foreseeable operating condition?”

Risk assessment guidance for collaborative applications specifically considers potential collisions, foreseeable misuse, and hazards created by the complete application—not only by the robot arm.

Which Robot Safety Components Are Available?

The right product depends on the hazard, the direction from which a person may approach, the required stopping response, and how frequently operators need access to the process.

Safety Laser Scanners

Safety laser scanners monitor configurable two-dimensional areas around robot cells, machines, palletizing stations, or mobile equipment. They are particularly useful when an open workspace is preferred over a fixed perimeter fence.

Many scanners support several warning and protective fields. As a person approaches, the safety system may first reduce the robot’s speed. If the person enters a closer protective field, the system can initiate a safety-rated stop.

Typical applications include:

• open robot cells,

• palletizing and depalletizing stations,

• machine loading areas,

• material transfer points,

• flexible manufacturing workspaces,

• speed and separation monitoring,

• industrial mobile robots.

A scanner’s protective fields must be configured for the application, and the complete stopping time must be considered when determining field dimensions. Safety laser scanners can also support dynamic protective zones that change according to operating mode or robot movement.

Safety Light Curtains and Light Grids

Safety light curtains create an invisible detection field between a transmitter and receiver. When a person or body part interrupts the field, the safety system performs the defined response.

They are well suited to clearly defined openings where people need regular access or materials must move in and out of a safeguarded area.

Typical applications include:

• access points to robot cells,

• manual loading stations,

• material transfer openings,

• assembly workstations,

• conveyor interfaces,

• frequent part changes.

Depending on the selected resolution, a light curtain may be designed to detect fingers, hands, or a person’s body. Unlike a laser scanner, it normally monitors a defined plane rather than a freely configurable floor area.

A light curtain is often the more suitable choice when the access path is clearly defined. A scanner is generally more flexible when an open area must be monitored from several approach directions.

Perimeter Guards, Doors, and Interlock Switches

Physical guarding prevents people from entering the robot’s hazardous operating space during automatic operation. Common solutions include perimeter fencing, enclosures, fixed panels, and access doors with safety interlocks.

An interlock switch detects whether a guard door is closed. A guard-locking device can additionally prevent the door from being opened until hazardous motion has stopped.

Physical separation is often appropriate for applications involving:

• high robot speeds,

• heavy payloads,

• sharp or hot tooling,

• welding, cutting, or machining processes,

• ejected or falling workpieces,

• hazards that remain after robot motion stops.

In the United States, OSHA’s general machine-guarding requirement states that one or more safeguarding methods must protect operators and other employees from machine hazards. OSHA does not currently maintain a robotics-specific standard, so robot applications must also be considered within broader machine-safety obligations.

Safety Relays and Safety Controllers

Robot safety systems require logic that evaluates signals from scanners, light curtains, door switches, E-stops, and other protective devices.

A safety relay is often suitable for a limited number of straightforward functions. A programmable safety controller or safety PLC is typically more appropriate when multiple zones, operating modes, robots, and machines must be coordinated.

The required architecture depends on the risk assessment, required safety integrity, communication interfaces, and future expansion plans.

A more capable controller is not automatically the better solution. For a simple stand-alone safeguard, unnecessary programming complexity can increase engineering and validation effort.

Emergency Stops and Enabling Devices

An emergency stop allows an operator to interrupt a hazardous situation quickly. It is a complementary protective measure and should not be used as a substitute for normal safeguarding.

The E-stop function, reset behavior, stopping category, and placement must match the application. Resetting the device should not automatically restart hazardous robot motion.

Enabling devices are commonly used during setup, teaching, troubleshooting, or test operation. The operator must intentionally hold the device in an enabled position. Releasing it—or, with a three-position device, squeezing it fully—causes the hazardous motion to stop.

These devices are especially relevant when a qualified person must enter or remain near the robot workspace while performing controlled movements.

Safety-Rated Motion and Drive Functions

Modern robot controllers and drives can provide safety-rated functions that control torque, speed, position, direction, and stopping behavior.

Depending on the robot and controller, available functions may include:

• Safe Torque Off,

• safety-rated monitored stop,

• safely limited speed,

• safe position or workspace limits,

• safe direction monitoring,

• safe brake control,

• safe stopping functions.

These functions can support more flexible safety concepts than a simple power disconnection. For example, a robot may operate at reduced speed while a person is nearby and stop only when a closer protective zone is entered.

Function names, available options, reaction times, and supported safety levels vary by manufacturer and controller generation. Compatibility must therefore be verified before selecting external safety components.

Which Safety Solution Fits Your Application?

Product selection should begin with the hazard and the required risk reduction—not with a preferred sensor.

This table provides initial guidance only. The final solution must reflect the risk assessment, measured stopping time, possible access routes, and required safety performance.

Safety Laser Scanner or Light Curtain?

Both technologies provide non-contact personnel detection, but they monitor different spaces and solve different problems.

Choose a scanner when people may approach from several directions or when the process benefits from warning and protective zones.

Choose a light curtain when access occurs through a defined opening and reliable detection across that plane is required.

The decision must also consider contamination, reflections, blind zones, mounting position, response time, required resolution, and possible access above, below, or around the protective field.

What Is Functional Safety in Robotics?

Functional safety in robotics refers to the part of overall safety that depends on safety-related control systems performing correctly.

A typical safety function may work as follows:

1. An interlock detects that a guard door has opened.

2. A safety controller evaluates the signal.

3. The robot controller or drive performs the required safety-rated stop.

4. Restart remains inhibited until defined reset and restart conditions are met.

The required safety level applies to the complete chain of sensing, logic, and actuation. It is not sufficient for only one component to meet the target performance.

ISO 13849-1 and IEC 62061 provide widely used approaches for designing and evaluating safety-related control systems. The selected method depends on the system architecture, applicable standards, and project requirements.

Functional safety robotics projects must also consider diagnostic coverage, fault detection, common-cause failures, software, communication paths, and periodic testing—not only nominal component performance.

Industrial Robot Safety and Collaborative Robot Safety

Traditional industrial robot applications commonly use perimeter guarding to separate personnel from hazardous automatic motion. Interlocked doors, safety controls, and drive functions prevent operation when the safeguarded space is accessed.

In a collaborative application, a person and robot may share all or part of the workspace. Common collaborative operating approaches include safety-rated monitored stop, hand guiding, speed and separation monitoring, and power and force limiting.

Collaborative robot safety does not mean that every application can operate without additional safeguards. The end effector, workpiece, speed, payload, contact geometry, process hazards, and accessible trapping points all affect the risk.

A cobot may therefore require a scanner, light curtain, guard, speed reduction, or redesigned tooling despite having integrated safety functions.

The central principle of cobot safety is that the complete application must be assessed and validated. A collaborative robot arm alone does not make the process collaborative. Current industry guidance explicitly emphasizes that risk assessment remains necessary and that the tooling and process can create hazards beyond the robot itself.

Risk Assessment Before Selecting Products

A robot risk assessment should be completed before the safety concept and components are finalized.

The assessment evaluates hazards throughout the full lifecycle of the application, including:

• transportation and installation,

• commissioning,

• automatic production,

• loading and unloading,

• setup and teaching,

• cleaning,

• troubleshooting,

• maintenance,

• decommissioning.

A structured process usually includes:

1. Define the intended use and limits of the application.

2. Identify hazards and possible access routes.

3. Estimate and evaluate the risks.

4. Reduce risk through inherently safe design where possible.

5. Define necessary safeguards and safety functions.

6. Determine the required safety performance.

7. Select and integrate suitable components.

8. Verify and validate every safety function.

9. Document the results and residual risks.

The updated ISO 10218-1:2025 addresses safety requirements for industrial robots, while ISO 10218-2:2025 covers industrial robot applications and robot cells. The U.S. ANSI/A3 R15.06-2025 standard was adapted from these revised international standards and includes requirements for robots, integrated applications, and robot-cell use.

Robot Safety Standards and the U.S. Regulatory Context

The applicable requirements depend on the country, industry, machine, and intended use. For U.S. industrial applications, buyers and integrators should distinguish between regulatory requirements and voluntary consensus standards.

OSHA currently states that there are no robotics-specific OSHA standards. However, broader requirements still apply, including machine guarding under 29 CFR 1910.212 and control of hazardous energy during servicing and maintenance under 29 CFR 1910.147. OSHA also publishes technical guidance for recognizing and reducing robot hazards.

Important robot safety standards and guidance may include:

ANSI/A3 R15.06-2025 replaced the earlier 2012 U.S. edition and is the current U.S. industrial robot safety standard. The ANSI/A3 R15.08 series separately addresses industrial mobile robots and their applications.

Standards do not replace application-specific engineering. A qualified safety professional or integrator should confirm which requirements apply to the particular installation.

Why Are Stopping Time and Safety Distance Important?

A presence-sensing safeguard must detect a person early enough for the hazardous motion to stop before the person can reach it.

The required protective distance depends on the total system response, including:

• sensor response time,

• safety-controller processing time,

• communication delay,

• robot and tooling stopping time,

• approach direction,

• assumed human approach speed,

• detection capability,

• access above, below, or around the protective field.

A fast sensor alone does not guarantee a short safety distance. The actual stopping behavior of the robot, end effector, workpiece, and process must be included.

Stopping time should be measured under representative operating conditions. Payload, speed, tool orientation, wear, and brake condition can affect how long the application requires to reach a safe state.

The protective-device location should then be calculated and validated using the applicable standards and measured values rather than estimated from the robot specification alone.

Compatibility with the Robot and Safety Controller

Before purchasing a safety component, verify how it will communicate with the robot controller and the rest of the cell.

A simple safety-rated input may be sufficient to initiate a stop. More advanced applications may require safety-rated fieldbus communication, safe position data, multiple operating modes, or manufacturer-specific safety options.

Important questions include:

A safety component should therefore be selected for the specific robot controller and application—not only for the robot brand.

What Information Should You Prepare for a Consultation?

A useful consultation begins with a clear description of the complete application. The following information helps narrow down appropriate products and safety concepts.

A cell layout, photos, video of the intended process, and information about pedestrian and forklift routes are also valuable.

These details help determine whether the application requires physical guarding, area monitoring, access protection, safe speed reduction, or a combination of measures.

Common Robot Safety Planning Mistakes

Many safety problems result from selecting products too early or evaluating only the robot arm.

Common mistakes include:

• choosing a scanner or light curtain before completing the risk assessment,

• assuming a cobot is automatically safe without guarding,

• ignoring hazards created by tooling and workpieces,

• estimating safety distances rather than calculating and validating them,

• overlooking access above, below, or beside a protective field,

• using an E-stop as the primary safeguard,

• confusing standard control functions with safety-rated functions,

• failing to verify robot-controller compatibility,

• excluding maintenance and troubleshooting from the assessment,

• delaying validation and documentation until the end of the project.

Another frequent error is designing the safety system only for normal automatic production. Many serious hazards arise during setup, jam clearing, tool changes, cleaning, and maintenance, when people are closer to the equipment and standard production safeguards may be bypassed or disabled.

Lockout/tagout requirements must also be considered where servicing or maintenance could expose employees to unexpected energization, startup, or release of stored energy.

How Much Does a Robot Safety System Cost?

The total cost depends on the complete safety concept rather than the price of a single device.

A basic application with one interlocked door and a simple safety relay may require relatively few components. An open robot cell with several scanner fields, safety-rated speed control, multiple operating modes, and networked safety logic requires more hardware, programming, testing, and documentation.

Cost factors can include:

• number and type of access points,

• size and geometry of the safeguarded area,

• stopping time and required protective distance,

• required Performance Level or SIL,

• available robot safety functions,

• safety PLC and network architecture,

• wiring and installation,

• programming and commissioning,

• verification and validation,

• training, inspection, and documentation.

The lowest hardware price does not necessarily produce the lowest total cost.

A properly designed system may reduce unnecessary stops, support faster controlled restart, improve diagnostics, and require less floor space. A poorly matched device may create frequent nuisance trips, difficult troubleshooting, or expensive redesigns during commissioning.

When comparing products, consider the total cost of integration and operation—not only the purchase price.

Frequently Asked Questions About Robot Safety

Is a Cobot Automatically Safe Without a Fence?

No. Whether a collaborative robot can operate without perimeter guarding depends on the complete application. Speed, force, tooling, workpiece, trapping points, and possible contact must be evaluated through a risk assessment.

What Is the Difference Between a Safety Relay and a Safety PLC?

A safety relay is suitable for relatively simple functions with a limited number of inputs and outputs. A safety PLC is programmable, scalable, and usually better suited to complex cells with several safeguards, zones, operating modes, or robots.

Can a Safety Laser Scanner Only Stop a Robot?

No. When integrated with suitable safety-rated controls, a scanner can monitor several zones. The robot may first reduce speed and then perform a safety-rated stop if a person enters a closer field.

Does a Certified Safety Component Make the Robot Cell Compliant?

No. Certification of an individual component does not replace risk assessment, correct integration, validation, employee procedures, or compliance of the complete machine.

Can an Existing Robot Cell Be Retrofitted?

Many cells can be upgraded with scanners, interlocks, light curtains, safety controllers, and additional safe motion functions. The existing controller, interfaces, stopping time, documentation, and mechanical layout must be reviewed before selecting components.

What Is a Performance Level?

A Performance Level describes the ability of a safety-related control function to achieve the required risk reduction under foreseeable conditions. The required level is determined through risk assessment and applies to the complete safety function.

What Is the Difference Between Robot Safety and Machine Safety?

Robot safety focuses on hazards created by the robot, its motion, tooling, workpieces, and robot application. Machine safety robotics also considers the surrounding machine, conveyors, process equipment, energy sources, access points, and all interactions within the integrated system.

Who Is Responsible for Robot Safety?

Responsibilities may be shared among the robot manufacturer, integrator, machine builder, employer, and end user. The exact obligations depend on the jurisdiction, contract, and project scope. The final integrated application must be risk-assessed, safeguarded, validated, documented, and operated according to applicable requirements.

Compare Robot Safety Components on the RBTX Marketplace

A reliable safety concept begins with the risk assessment and does not end with the selection of one sensor. Detection capability, protective fields, stopping time, control architecture, safe robot functions, and compatibility must work together.

On the RBTX Marketplace, you can compare safety laser scanners, light curtains, interlock switches, E-stops, safety relays, and control solutions from multiple manufacturers.

Evaluate products based on your technical requirements, compare compatible components, request a quote, or get guidance in selecting the right safety solution for your robot application.