Robot Safety Application Series (2): Manual Loading and Unloading

Danger of manual tasks

In the current application of various types of industrial robots , it is often necessary to manually intervene in turning, fixtures and other tooling for manual loading, unloading or handling tasks.

In the area where the manual task and the robot action intersect, the personnel are frequently involved. The tooling is usually equipped with actuators such as jaws and cylinders, which may cause movements such as turning, rotation, etc., and thus often accompanied by potential dangers such as crushing, shearing, and entanglement. .

In order to ensure that operators are not exposed to the dangers posed by such tasks, it is necessary to provide targeted protection.

Operator intervention

Main protection measures

As the main measure of risk reduction in ISO 12100, interlocks and mechanical fences are the most versatile methods, which also apply to robot-related safety protection.

For example, a fixed guard should meet the following general requirements:

● Can only be removed by using a specific tool (such as an Allen key);

● When the guard is removed, the fixings (such as screws) should remain attached to the shield or the machine body;

● The height of the guard is at least 1400 mm from the ground.

These requirements are derived from the international standards ISO 14120 and ISO 13857 and are documented in the Robot Safety Standard ISO 10218-2 as a general rule of protection.

The main guard of the robot

Additional protection

Many manual loading and unloading tasks may involve very frequent interventions. The physical protection of interlocking devices and mechanical fences is not allowed in the process. After fully considering the risk of divergence (such as part ejection, welding sparks, etc.), the following three types can be considered. Additional protection measures:

Stop time limit

The design control system has sufficient stopping time to turn the internal hazard into a safe state before the operator approaches the hazard.

Usually, the control system needs to use the interlocking protection with locking to make a reasonable unlocking signal. Through delay, speed monitoring, static detection, etc., the equipment is in a safe state before the personnel approach the dangerous area.

Use the light curtain to trigger the machine to stop

Collaborative space limitation

When the robot and the operator have a common workspace, design the workflow and the corresponding control system to ensure that they do not occupy the workspace at the same time. Once the workspace is occupied at the same time, it will trigger a safe stop of the robot.

Limit collaboration space

For the various hazards arising from human-computer interaction, Pilz has developed a new human-machine collaboration and safety application course based on ISO/TS 15066, which is suitable for robot-related engineers in various industries.