Risk Assessment for Robotic Cell Guarding

A robotic cell guarding risk assessment should consider more than the movement of the robot arm. The assessment must identify hazards created by the complete cell, including end effectors, tooling, workpieces, conveyors, palletizers, transfer points and the way operators, maintenance personnel and cleaners access the area.

The purpose is to determine how people could be exposed to hazardous movement and what safeguarding measures are needed to control that exposure. This may include fixed guards, modular perimeter fencing, interlocked access gates, protective devices, controlled transfer openings and safety-related control functions.

A robot cell that appears enclosed can still present risk if people can reach through mesh, enter through a pallet opening, access an adjacent conveyor or remain inside the enclosure when the cell restarts.

Start With the Limits of the Robotic Cell

The assessment should begin by defining the limits of the complete robot system.

This includes:

• robot type, reach and maximum operating space
• robot speed, payload and intended tasks
• end effectors, grippers, welding tools or process tooling
• workpieces, pallets, fixtures and load-handling devices
• connected conveyors, palletizers and transfer equipment
• manual loading and unloading stations
• normal operating modes
• setup, teaching, maintenance and cleaning activities
• foreseeable faults, jams and recovery tasks
• surrounding pedestrian, forklift, AGV or AMR traffic

Do not assess the robot in isolation. A robot may have a limited base footprint while its arm, end effector, carried load or workpiece moves closer to the guard perimeter. The hazard zone may also extend to a pallet transfer system, conveyor discharge point or fixture outside the robot base area.

Identify Hazards in Every Operating Mode

Risk assessment should cover the full machine lifecycle, not only automatic production.

Potential robotic cell hazards include:

• crushing between the robot, tooling and fixed structures
• impact from robot arm, end-effector or workpiece movement
• trapping between moving equipment and the guard perimeter
• ejection or dropping of product, tooling or process material
• cutting, welding, hot surfaces or other process hazards
• conveyor nip points and transfer hazards
• unexpected restart after intervention
• stored pneumatic, hydraulic, electrical or mechanical energy
• access during fault recovery, cleaning or maintenance

The risk can change between automatic, manual, setup and maintenance modes. A reduced-speed teaching or setup mode may reduce some movement risks, but it does not automatically make all access safe. Tooling, payloads, stored energy, adjacent equipment and unexpected movement still need to be considered. Tooling, payload, stored energy, adjacent equipment and unexpected movement still need to be considered.

Assess Who Needs Access and Why

The access strategy is one of the most important parts of robotic cell guarding.

Identify who may need to access the cell:

• operators
• maintenance personnel
• cleaning teams
• setters and tool-change personnel
• engineers and integrators
• contractors
• supervisors or inspectors

Then identify why and how often access is needed:

• clearing faults or jams
• loading fixtures or material
• replacing tools or end effectors
• adjusting sensors or guides
• cleaning the cell
• inspecting equipment
• servicing conveyors or robot components
• recovering dropped product or damaged pallets

Where access is infrequent, fixed guards or guard sections intended to be removed using the appropriate tools may be suitable. Where regular access could expose a person to hazardous machine functions, an interlocked movable guard is commonly used as part of the wider machine safety system.

A gate should be placed near the actual task. If access is inconvenient, operators may reach through guarding, use a pallet opening as an entry point or remove panels.

Review the Guard Perimeter and Reach Paths

The guard perimeter must prevent or adequately restrict access to the complete danger zone.

Assess:

• distance from mesh panels to robot movement
• reach-through access at mesh openings
• reach-around access at guard ends and interfaces
• reach-under access beneath panels
• reach-over access at low fence sections
• openings around conveyors, chutes and services
• gaps beside walls, posts and machine frames
• pallet or product transfer openings
• raised platforms, pallets or structures that could create climbing access

The guard-to-hazard distance should be measured to the actual danger zone, not simply the robot base or outside of the machine frame.

In a modular machine guarding layout, standard panel widths and gate modules must not dictate the final perimeter. Where a panel joint, transfer opening or machine interface creates an unsafe gap, the layout should be changed or a purpose-designed section added.

Assess Material Transfer and Loading Openings

Robotic cells commonly need openings for pallets, totes, components, conveyors or other material flow.

These openings can become access paths if they are not designed carefully.

Review:

• load size, orientation and movement direction
• the nearest robot, tooling or conveyor hazard
• possible reach-through and reach-around paths
• whether a person could lean, crawl, step or enter through the opening
• product accumulation and jam-clearing requirements
• access from nearby pedestrian or vehicle routes
• whether a safety-rated protective device or controlled muting arrangement is needed

A loading opening that suits pallet flow may still allow access by a hand, arm, leg or person. The opening size, possible reach path, hazard location and safety distance need to be assessed together.

Assess Interlocked Gates and Restart Prevention

Opening a gate should not create uncontrolled access to hazardous robot movement.

Where personnel access could expose someone to hazardous robot movement or associated machine functions, an interlocked movable guard is commonly used. The assessment should then consider:

• the safe response required when the gate is opened
• robot and associated equipment stopping performance
• whether guard locking is required
• prevention of hazardous start or restart while access is open
• reset location and visibility of the cell
• foreseeable bypassing or defeat of the interlock
• interlock mounting, alignment and cable protection
• the safety-related control-system design and validation scope

If a person could reach the danger zone before hazardous movement or another machine-related risk has ceased, guard locking, increased separation distance or another suitable protective measure may be required. The decision should consider the relationship between stopping time and access time. This depends on the relationship between stopping time and access time.

Closing an interlocked gate should not, by itself, initiate hazardous restart. The restart arrangement should require deliberate action and allow the required safe conditions to be confirmed.

Consider Whole-Body Entry

Many robotic cells allow full-body entry for maintenance, recovery or cleaning. This creates additional risk because a person may remain inside the enclosure when the cell is reset or restarted.

The assessment should consider:

• potential for a person to become trapped inside
• internal release or exit arrangements
• visibility of the cell before restart
• controlled reset and restart procedures
• presence detection where appropriate
• communication between operators, maintenance personnel and control stations
• access to isolation points and emergency stop devices

Emergency stop devices are important complementary protective measures, but they do not replace controlled access, isolation or restart prevention.

Consider the Surrounding Area

The robotic cell should also be assessed in relation to the wider work area.

Review:

• pedestrian routes and access points
• forklift, pallet-jack, AGV or AMR traffic
• impact risk to guard panels, posts and interlocks
• adjacent machinery and shared transfer systems
• lighting and visibility
• emergency access arrangements
• space for maintenance carts, lifting equipment and component removal

A forklift impact or moved pallet stack can change the effectiveness of the guarding by damaging posts, creating gaps or providing a climbing point near the perimeter.

Relevant Standards and Technical Considerations

Robotic cell guarding risk assessment should be based on the specific application, applicable standards and local requirements.

Common international standards may include:

• ISO 12100 for machinery risk assessment and risk reduction
• ISO 10218-1 for industrial robot safety requirements
• ISO 10218-2 for robot applications and robot-cell integration
• ISO 14120 for the design and construction of guards
• ISO 14119 for interlocking devices associated with guards
• ISO 13857 for safety distances
• ISO 13849-1 for safety-related parts of control systems
• ISO 14118 for prevention of unexpected start-up
• ISO/TS 15066 for collaborative robot operations, where applicable

In Australia, the AS 4024 Safety of Machinery series addresses machinery safety topics including risk assessment, guarding, safety distances and safety-related control systems. Local regulatory requirements and industry-specific guidance should also be reviewed for the installation location.

Common Risk Assessment Mistakes

Common mistakes include:

• assessing only the robot arm and not the complete cell
• measuring from the robot base instead of the actual danger zone
• overlooking end effectors, tooling and carried loads
• leaving uncontrolled access at conveyor and pallet openings
• adding gates without assessing stopping performance
• ignoring full-body entry and restart prevention
• assuming collaborative operation removes the need for safeguarding
• failing to assess maintenance, cleaning and fault recovery
• changing cell layouts without reviewing guarding risk
• treating modular fencing as safe by default

A documented risk assessment should guide the guarding layout, safety controls and access strategy before the robot cell is installed or modified.

Conclusion

Risk assessment for robotic cell guarding should address the complete system: robot movement, tooling, workpieces, connected equipment, material flow, access tasks and surrounding traffic.

The key objective is to prevent or adequately restrict access to hazardous areas during every foreseeable operating condition, including normal production, cleaning, maintenance, fault recovery and restart.

If you are designing, upgrading or integrating a robotic cell, assess the complete hazard zone before selecting panels, gates or safety devices. A competent machinery safety specialist or guarding supplier can then help develop a practical guarding layout and access strategy for the application.

Frequently Asked Questions

What should a robotic cell guarding risk assessment include?

It should include robot movement, end effectors, tooling, workpieces, conveyors, pallet flow, access tasks, safety distances, gates, stopping performance, restart prevention and surrounding traffic.

Does every robotic cell need perimeter guarding?

Not necessarily. The safeguarding approach depends on the robot application, hazards, operating modes, payload, tooling, speeds and risk assessment. Many industrial robot cells use perimeter guarding with controlled access.

Are collaborative robots exempt from guarding requirements?

No. Collaborative operation does not automatically eliminate safeguarding needs. The full application, including tooling, payload, speed, surrounding equipment and foreseeable contact, still requires assessment.

Do robotic cell gates need interlocks?

Where opening the gate could expose a person to hazardous robot movement or associated machine functions, an interlocked movable guard is commonly used as part of the machine safety system.

When is guard locking needed on a robotic cell?

Guard locking may be needed where a person could reach the danger zone before hazardous movement or another machine-related risk has ceased after access is requested.

How should pallet openings in robotic cells be assessed?

Assess pallet size, opening dimensions, nearest hazards, possible reach paths, access from nearby routes and the likelihood of jams or manual intervention. The opening must support material flow without allowing unsafe human access.

Should robotic cell guarding be reviewed after changes?

Yes. Changes to tooling, payload, robot speed, conveyors, gates, product flow, access requirements or surrounding layout can affect the original risk assessment and safeguarding design.