Important Approaches for Safe Human-Robot Interaction
In the past industrial robot systems were separated from workers to protect them from unintended contact. Modern advancements have however increased the demand to bring the power and precision of robots closer together with the creativity of humans. Such interactive systems are known as “Cobots”.
Cobots have led to dramatic increases in productivity in the automotive and electronic industries. According to ISO standard ISO/TS 15066, which specifies safety requirements for collaborative industrial robot systems and the work environment, there are four important safety approaches to human-robot interaction:
1. Safety Monitored Stopping Controls
A safety monitored stop pauses the robot’s motion while the operator is in the shared workspace. The robot maintains its power but it cannot move in the space where a human and a robot perform tasks. When the workspace is clear of the operator(s), the cobot can however work at high speeds. This results in a faster cycle time. Robots can also start back up automatically once the workspace is clear.
2. Worker Guides the Robot
Hand guiding allows a cobot to move through direct physical input from the operator. The cobot stays in a ‘safety monitored stop’ until an operator actuates the hand guiding device through an enabling switch. Such assists are easier to maneuver than traditional designs. Hand-guided cobots can also work autonomously when the operators are not around.
3. Speed and Separation Monitoring
Speed and separation monitoring is often referred to as a “fenceless robot system”. These are common in shared manufacturing floors. The collaborative robot is able to move concurrently with the operator so long as they maintain a predetermined distance apart. Often a safety-rated laser area-scanner monitors this type of human/robot application. The distance can vary based on how fast the cobot is moving.
4. Power and Force Limitations
Limitations on power and force require a type of robot that has power or force feedback built into it. A limitation system lets the cobot detect physical contact with the operator. It is possibly the most popular type of cobot but requires an extensive risk assessment and risk controls. This is due to the fact that the operator is within reach of the cobot.
