What Is Risk Assessment in Robotics? How Machine Hazards Are Evaluated.

What Is Risk Assessment?

Risk assessment is the systematic process of identifying hazards, evaluating associated risks, and determining appropriate measures to reduce those risks.

In industrial robotics, risk assessment considers the complete application, including the robot, tools, workpieces, surrounding equipment, and people who may interact with the system.

For example, a robotic arm installed beside an assembly line may create hazards involving crushing, sharp tools, or unexpected movement.

Risk assessment helps determine what protective measures are necessary before the system enters operation.

Key Takeaways

• Risk assessment identifies hazards and evaluates the possibility and consequences of harm.
• It must consider normal operation, maintenance, foreseeable misuse, and potential failures.
• A robot's built-in safety features do not eliminate the need to assess the complete application.

How Does Robot Risk Assessment Work?

Imagine a manufacturer installing a robotic palletizing cell.

The robot lifts heavy cartons and stacks them onto pallets.

Engineers begin by identifying the tasks that the system will perform and the people who may interact with it.

They examine possible hazardous situations.

For example, a worker could enter the robot's operating area to remove a damaged carton.

The robot might also drop a load or move unexpectedly.

The assessment considers the severity of potential harm and the circumstances in which a person could be exposed.

Engineers then determine suitable protective measures.

After those measures are implemented, the remaining risks are evaluated.

The process should be documented and reviewed when relevant changes occur.

Hazard vs. Risk

A hazard is a source or condition with the potential to cause harm.

Risk concerns the likelihood and severity of harm arising from exposure to that hazard.

Consider a robotic arm carrying a heavy metal component.

The moving load creates a potential crushing hazard.

The level of risk depends on factors such as whether people can enter the operating area, what protective measures exist, and how the robot behaves.

The same hazard can present different risks in different applications.

What Are Common Risk Reduction Measures?

Risk reduction generally prioritizes measures that eliminate or reduce hazards through design.

Additional measures can include:

Physical guarding: Restrict access to hazardous machinery.

Interlocks: Monitor protective guards and initiate defined responses.

Safety-rated sensing: Detect entry into protected areas under specified conditions.

Safety-related control functions: Provide protective stopping, speed monitoring, or other required functions.

Procedures and training: Help workers understand operating restrictions and remaining risks.

The appropriate combination depends on the application.

Training and warning signs should not be treated as substitutes for necessary engineering safeguards.

Risk Assessment vs. Functional Safety

Risk assessment determines which hazards and risks need to be addressed.

Functional safety concerns the dependable operation of defined safety-related control functions.

For example, risk assessment may determine that a robot must stop hazardous movement when a protective gate opens.

Functional safety engineering helps ensure that the interlock and stopping function achieve the required performance.

The two activities are closely connected.

Why Are Cobots Not Automatically Safe?

Collaborative robots may include features intended to support applications involving nearby workers.

However, the complete task determines the hazards.

A cobot carrying a sharp tool could create a cutting hazard.

A heavy workpiece could create a crushing hazard.

The robot's collaborative designation does not eliminate these conditions.

The complete application must still be evaluated.

When Should Risk Assessment Be Performed?

Risk assessment should begin during system design and continue through relevant stages of development and deployment.

It should also be reviewed when significant changes occur.

For example, replacing a soft gripper with a sharp metal tool can change the hazards even when the robot arm remains the same.

Changes to speed, payload, layout, or operating procedures may also affect the assessment.

Frequently Asked Questions

Does a robot passing a factory acceptance test eliminate the need for risk assessment?

No. Acceptance testing and risk assessment serve different purposes.

Can risk assessment guarantee zero risk?

No. Its purpose is to identify and reduce risks to an acceptable level under applicable requirements. Residual risks may remain.

The Bottom Line

Risk assessment provides the foundation for designing and operating robotic systems with appropriate safeguards. It must address the complete application and the actual activities people perform around the equipment.