Pilz Robotics Safety Application Series II: Manual Handling

The Risks of Manual Tasks

In many industrial settings, robots are used for a wide range of tasks, but human involvement is still necessary in certain areas. For example, operators often need to manually load, unload, or handle parts using turntables, jigs, and other fixtures. This interaction between humans and machines can create potential hazards.

These manual operations frequently take place in zones where robotic movements occur. The tooling used in such setups often includes jaws, cylinders, and other actuators that may move unpredictably, leading to risks like crushing, shearing, and entanglement. Therefore, it's crucial to implement proper safety measures to protect workers from these dangers.

To ensure the safety of operators, targeted protective measures must be in place. These measures help reduce the risk of accidents by limiting access to dangerous areas and ensuring safe machine operation.

Operator Involvement

Key Protective Measures

One of the primary methods for reducing risk, as outlined in ISO 12100, is the use of interlocking devices and mechanical barriers. These are widely applied in robot safety systems to prevent unauthorized access to hazardous areas.

For instance, fixed guards should meet the following general requirements:

• They should only be removable with special tools, such as an Allen wrench.
• The fasteners, like screws, should remain attached to the guard or the machine body when removed.
• The height of the guard should be at least 1,400 mm above the floor.

These guidelines come from international standards such as ISO 14120 and ISO 13857 and are also included in the robot safety standard ISO 10218-2.

Main Protection Device for Robots

Additional Safety Measures

When manual tasks require frequent operator intervention, physical barriers may not always be practical. After considering all possible risks—such as flying debris or welding sparks—three additional protection strategies can be considered:

- **Stop Time Limit**: The control system must have enough time to stop the robot before an operator enters a dangerous area, ensuring the system transitions into a safe state.

This typically involves using a locked interlock system that sends a signal to stop the robot. The system should monitor speed, detect stationary positions, and delay access until the machine is fully stopped and safe.

Using Light Curtains to Stop the Machine

Collaboration Space Restrictions

When robots and humans work in the same space, the workflow and control system should be designed to prevent them from being in the same area at the same time. If both are present, the robot must automatically stop to avoid any risk.

Restricting the Collaboration Area

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