Collaborative Robots Safely Sharing Workspaces with Human Employees

Co-working robots are, for the most part, safe for humans to work alongside. The key really lies in their design and how they’re implemented. Unlike their larger, caged industrial cousins, collaborative robots (cobots) are built with safety features right into their core, allowing them to share workspaces without the need for extensive physical barriers. This isn’t to say there are zero risks, but with proper planning and adherence to safety standards, those risks are very low.

Traditional industrial robots are powerful, fast, and generally operate within guarded enclosures. They’re designed for high speed and heavy lifting, and any human entering their work envelope is a serious safety concern. Cobots, on the other hand, are designed from the ground up for human interaction.

Built-in Safety Features

A cobot’s internal programming and hardware are constantly monitoring its environment and its own movements.

• Speed and Force Limiting: This is perhaps the most fundamental safety feature. Cobots are programmed to operate at lower speeds and with limited force, especially when human presence is detected. If they encounter resistance, even light resistance, they can slow down or stop completely.
• Safety-Rated Monitored Stop: When a human enters a designated safety zone, the cobot can be programmed to stop its movement entirely, and in a way that is monitored and considered safe according to international standards.
• Hand Guiding: Some cobots allow an operator to physically guide them through a task, teaching them movements. This is only possible because of their inherent safety mechanisms.
• Power and Force Limiting (PFL): This goes beyond just slowing down. PFL cobots are designed to limit the amount of power and force they can exert. If they come into contact with a person, the impact is minimized to prevent injury. They’re often characterized by rounded edges and softer materials to further reduce impact severity.

Designed for Proximity

The physical design of cobots also plays a role in their safety. They tend to be smaller, lighter, and more agile than traditional robots.

• Smaller Footprint: Their compact size means they can fit into existing workspaces without significant reconfiguration, making cohabitation easier.
• Lighter Materials: Many cobots are constructed with lighter materials, which inherently reduces the kinetic energy in the event of a collision.
• Smooth, Rounded Edges: This might seem minor, but avoiding sharp corners and protrusions helps prevent cuts and scrapes if accidental contact occurs.

In the realm of industrial automation, ensuring the safe interaction between collaborative robots and human employees is crucial for enhancing productivity while minimizing risks. A related article that provides insights into optimizing workplace efficiency through technology is available at Best Software for Small Business in 2023. This resource discusses various software solutions that can aid businesses in integrating collaborative robots into their operations, thereby fostering a safer and more efficient work environment.

Key Takeaways

• Clear communication is essential for effective teamwork
• Active listening is crucial for understanding team members’ perspectives
• Setting clear goals and expectations helps to keep the team focused
• Regular feedback and open communication can help address any issues early on
• Celebrating achievements and milestones can boost team morale and motivation

Understanding the “Safety” Standards

When we talk about cobot safety, we’re not just talking about common sense; there are specific international standards that govern their design and deployment. Adhering to these standards is crucial for safe operation.

These are the foundational standards for safety requirements for industrial robots.

• ISO 10218-1: Focuses on the robot itself, covering its design, construction, and safety functions.
• ISO 10218-2: Deals with safety requirements for robot systems and their integration, including how they interact with other machinery and, importantly, humans.

ISO/TS 15066: The Cobot-Specific Standard

This technical specification is the real game-changer for collaborative robots. It elaborates on the four collaborative operation modes and provides guidelines for safe human-robot interaction.

• Power and Force Limiting: This section defines the maximum forces and pressures a cobot can exert on different parts of the human body without causing injury. It includes detailed charts for various body parts, guiding manufacturers and integrators to ensure safe contact limits.
• Safety-Rated Monitored Stop: This details the requirements for a robot to stop in a safe, monitored state when a human enters the collaborative workspace.
• Speed and Separation Monitoring: This mode allows the cobot to operate at a higher speed when a human is further away, and slow down or stop as the human gets closer. The standard provides formulas and guidelines for calculating safe separation distances based on robot speed and human reaction time.
• Hand Guiding: Requirements for safely guiding a robot by hand, ensuring that unintended movements or power surges are prevented.

The Human Factor in Cobot Safety

While cobots are designed with safety in mind, human operators and integrators play an equally critical role in ensuring a safe working environment. It’s not just about the robot; it’s about the entire system.

Before any cobot is introduced into a workspace, a thorough risk assessment must be performed. This is not a one-time event; it should be reviewed periodically and whenever changes are made.

• Identify Hazards: What are the potential pinch points, crush zones, or points of impact?
• Evaluate Risks: How likely are those hazards to occur, and what would be the severity of the injury?
• Implement Mitigation Strategies: This could involve adjusting the cobot’s speed, defining safety zones, or adding additional guarding for specific tasks.
• Documentation: All findings and mitigation measures must be clearly documented. This protects both the employees and the organization.

Proper Training is Essential

Even the safest technology can become hazardous without proper training.

• Operational Training: Employees need to understand how the cobot works, its capabilities, and its limitations. This includes basic programming, troubleshooting, and emergency stop procedures.
• Safety Training: This goes beyond just operating the cobot.

  It includes understanding the specific collaborative modes, recognizing potential hazards, and knowing how to react in different scenarios. For instance, knowing what to do if the cobot malfunctions or if a person inadvertently enters a restricted zone.

• Emergency Procedures: All personnel working near cobots should know the location of emergency stop buttons, how to activate them, and what to do after a stop event.

Ergonomics and Workspace Design

A safe collaborative workspace isn’t just about the robot; it’s about how the robot and human interact with the environment.

• Clear Work Zones: Defining areas where the cobot operates alone, where it collaborates with humans, and where humans have exclusive access. This can often be done with floor markings or light curtains.
• Lighting and Visibility: Ensuring adequate lighting allows both the cobot’s vision systems and human operators to clearly see the workspace and any potential hazards.
• Accessibility of Controls: Emergency stop buttons and other critical controls should be easily accessible to all operators.
• Avoiding Obstacles: The workspace should be free of clutter and unnecessary obstacles that could impede the robot’s movement or create tripping hazards for humans.

Collaborative Robot Operation Modes

ISO/TS 15066 defines four distinct modes of collaborative operation, each with specific safety requirements. Understanding these helps in properly deploying a cobot.

1. Safety-Rated Monitored Stop

This is the most basic collaborative mode. The robot system stops when a human enters its workspace.

• How it Works: Sensors (like light curtains or laser scanners) detect human presence. Upon detection, the robot immediately stops in a safe, monitored state and won’t resume motion until the human has left the designated area and a reset signal is given.
• Applications: Useful for tasks where the human needs to load or unload parts within the robot’s reach, but the robot performs its task independently. It’s like having a virtual fence.

2. Hand Guiding

In this mode, an operator can physically guide the robot to perform tasks or teach it new movements.

• How it Works: The robot’s power and force are limited, and it’s designed to be easily manipulated by an operator. A button or sensor on the robot arm allows the human to take control of its movement.
• Applications: Ideal for tasks requiring precise, but variable, movements or for learning new paths. This can drastically reduce programming time for complex tasks.

3. Speed and Separation Monitoring

This mode allows the robot to operate at a higher speed when no human is present and to slow down or stop as a human approaches.

• How it Works: Proximity sensors continuously monitor the distance between the human and the robot. As the human gets closer, the robot’s speed is reduced proportionally. If the minimum safe separation distance is breached, the robot will come to a complete stop.
• Applications: Suited for applications where the human sporadically enters the robot’s workspace, allowing for increased productivity compared to a full stop every time.

4. Power and Force Limiting

Often considered the “true” collaborative mode, as it allows for direct contact between the human and the robot without causing injury.

• How it Works: The robot’s inherent design and control system ensure that the maximum force and power it can exert are below injury thresholds for various parts of the human body. If contact occurs, the robot registers the impact and immediately stops or reverses its motion away from the contact point.
• Applications: Tasks requiring direct, physical cooperation, such as assembling small parts, polishing, or inspection where the robot holds an item while the human works on it. This mode is heavily reliant on ISO/TS 15066 guidelines for maximum permissible force and pressure.

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Real-World Considerations Beyond the Lab

While theoretical safety is excellent, practical implementation involves addressing several real-world facets.

Environmental Factors

The work environment itself can impact safety.

• Dust and Debris: Can interfere with sensors or robot mechanisms. Regular cleaning and maintenance are crucial.
• Temperature and Humidity: Extreme conditions can affect robot performance and sensor accuracy.
• Vibrations: Can cause unintended movements or affect sensor readings.
• Noise: While not directly a safety risk from the robot, excessive noise in a shared workspace can hinder communication and situational awareness.

Dynamic Work Environments

Workspaces are rarely static. Employees move, tools are changed, and processes evolve.

• Re-evaluation with Changes: Any significant change to the work cell, the robot’s task, or the surrounding environment necessitates a new risk assessment. This includes adding new tools, changing the layout, or even altering the parts being processed.
• Employee Behavior: Humans are unpredictable. Training needs to emphasize consistent and safe interactions, but the system should also be robust enough to handle unexpected actions.
• Tooling and End Effectors: The safety of a cobot often depends on its end effector (the “hand”). A well-designed cobot arm can become hazardous if fitted with a sharp or heavy end effector. These must also be subject to the same rigorous safety assessment.

Maintenance and Downtime

Even robots need attention.

• Scheduled Maintenance: Regular checks of sensors, cables, and mechanical parts are vital to ensure continued safe operation.
• Software Updates: Keeping the robot’s software up-to-date ensures all safety protocols and features are current.
• Troubleshooting: Operators should be trained on basic troubleshooting to identify and address minor issues that could potentially compromise safety if left unaddressed. Always refer to qualified technicians for complex issues.

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The Bottom Line

Collaborative robots are a significant step forward in automation, bridging the gap between fully automated processes and purely manual labor. Their ability to safely share workspaces with human employees is a testament to sophisticated engineering and rigorous safety standards. However, “safe” doesn’t mean “carefree.” It demands a proactive approach involving comprehensive risk assessments, adherence to international safety standards, thorough employee training, and ongoing vigilance. When these elements align, cobots don’t just work alongside humans; they work with them, enhancing productivity and creating a more efficient and, crucially, safer workplace.

FAQs

What are collaborative robots?

Collaborative robots, also known as cobots, are robots designed to work alongside humans in a shared workspace. They are equipped with sensors and safety features to ensure they can safely interact with human employees.

How do collaborative robots ensure safety in shared workspaces?

Collaborative robots use a variety of safety features such as force and speed limitations, safety-rated monitored stop, hand guiding, and power and force limiting to ensure they can safely work alongside human employees without causing harm.

What are the benefits of using collaborative robots in the workplace?

Collaborative robots can increase productivity, improve efficiency, and enhance the overall safety of the workplace. They can also handle repetitive or dangerous tasks, allowing human employees to focus on more complex and strategic work.

What industries commonly use collaborative robots?

Collaborative robots are commonly used in industries such as manufacturing, logistics, healthcare, and agriculture. They can be utilized for tasks such as assembly, packaging, material handling, and quality inspection.

What are the limitations of collaborative robots in shared workspaces?

While collaborative robots are designed to work safely alongside humans, there are still limitations to their capabilities. They may not be suitable for all tasks, and proper risk assessments and safety protocols should be in place to ensure safe interaction with human employees.