Human-robot collaboration: How we're going to work together with the robot in the future

Robots have been an indispensable part of our industry for decades. They help in industrial assembly, as driverless transport systems in logistics and generally in production. But high safety requirements often keep robots and humans physically separate. Previous robot systems are usually fenced in production in order not to endanger the human workers. Protective fences and doors as well as light barriers ensure the safety of people, but also limit the efficiency of machines.

But this is to change in the future. The aim is to have collaborative robots in manufacturing that can work with humans directly in the same work space, for example in industry, logistics, but also in medicine and in the care sector in the form of assistant robots. That is why Fraunhofer Institut für Kognitive Systeme IKS is conducting research on safe human-robot collaboration (HRC).

Especially in industry, human-robot collaboration brings many advantages.

What is human-robot collaboration (HRC)?

Humans work with the robot without a protective fence, without separation. This is the simplest definition of human-robot collaboration (HRC). Human-robot collaboration thus comes at the end of a series of different stages in how humans and machines can interact with each other:

  • Strict separation of the work areas: In classic industrial plants, robot systems were and are strictly separated from human workers. They have their own cell, which is clearly delimited by a protective fence and which humans usually do not enter. If this happens nevertheless, the operation will be stopped automatically, to ensure human robot collaboration safety.
  • Coexistence: In case of human robot coexistence, the protective fence will be removed. But humans and machines still have different work areas. They do not work together.
  • Cooperation: In case of cooperation, humans and industrial robots share one working space. However, they do not work together on a product, but in a time-shifted manner.
  • Collaboration: Here, humans and robots work hand in hand. They have a common work area and work on the same part at the same time.

Advantages of human-robot collaboration

The advantages of human-robot collaboration are obvious: Good cooperation between humans and robots can increase production efficiency. Protective fences are removed and people as well as robots can move more freely. Processes in the factory are optimized. HRC makes Industry 4.0, i.e. the efficient, flexible and individual production through automation technology, a reality. This makes the company future-proof and saves costs through efficient production.

At the same time, the workforce in production is relieved: Robotic systems can take on annoying, ergonomically unfavorable and thus strenuous work, such as lifting loads or overhead work. This protects the health of employees. Workers can instead focus on more complex tasks that require their human expertise.

Disadvantages of human-robot collaboration

But even the best system has disadvantages: In human-robot collaboration, efficiency doesn't always mean maximum speed. Since humans and machines work closely together here, the robot system must watch out for humans and, if necessary, reduce the speed in order to minimize the risk of injury to human colleagues. However, intelligent software technology and good safety engineering can mitigate these disadvantages.

Protective mechanisms to ensure human-robot collaboration safety

In order to ensure the safety of people in the operation of human machine interaction systems, there are guidelines and standards that must be adhered to. An example is the standard DIN EN ISO 10218-1. It defines various protective mechanisms for safe human-robot collaboration, including:

  • Hand guiding: The robot movements are actively controlled by the worker. So the worker is in control of the action.
  • Speed and distance monitoring: The robots use sensors to monitor their surroundings. If a human gets too close, contact is prevented by the robot.
  • Power and force limits: Often, however, robots and humans should and must touch each other. In order to reduce the risk of injury to a minimum, the contact forces between employees and machines are therefore reduced to a riskless level. This is done, for example, by keeping the weight of the mobile robots as low as possible.

Adaptive safety: Safety in human-robot collaboration by Fraunhofer IKS

In order to minimize the limitations in human-robot collaboration and meet safety requirements, the Fraunhofer Institute for Cognitive Systems IKS is conducting research on “Adaptive safety”. This refers to methods and algorithms that - in connection with sensors and actuators - enable adaptable safety. Instead of static safety functions, adaptive safety functions are to be used in the future.

For example: A static safety function follows the principle “When the safety door is opened, then stop the system.” With an adaptive safety function, on the other hand, it looks like this: “When the safety door is opened, then switch to reduced operation for the immediate proximity. Operate all other areas normally.”

For different application areas, there are different scenarios for how Adaptive Safety can be implemented. A collaborating robot, also called a cobot, can detect whether an obstacle is in the way using torques or energy consumption measurements at the axle motors. Cameras or an artificial skin also allow the system to detect when it is touching a person, for example. However, Adaptive Safety goes one step further: Intelligent software enables the robot to assess the behavior of humans in advance and thus plan its movements with regard to the necessary safety requirements. For example, it would be possible to optimize the route or adjust the speed, even in case of driverless transport systems.

Another critical point in production is the intervention in productive operation, for example when a sensor must be readjusted but the current batch has to be further processed. Thanks to Adaptive Safety from Fraunhofer IKS, the machine does not have to stop the entire production. Thanks to sensor-based monitoring, it only secures the area in which people work. If the human leaves this zone again, the machine automatically switches to normal operation.

The vision of Fraunhofer IKS are cognitive production facilities and factory halls: In a cognitive factory hall, all objects, people and machines, can be localized and their intentions are recognizable. Humans and robots can thus work efficiently, safely and collaboratively.

Areas of application for human-robot collaboration

There are numerous areas of application for human-robot collaboration due to digitization and automation. Whether in production, logistics or care. Here are three examples:

Cobot - Working side by side on the same component

While the robot aligns the side lights on the car which are difficult to reach, the worker can readjust the main lights which are easier to reach. Thus, humans and machines work together on the same component without a protective fence, and the worker is relieved.

Driverless transport systems - Outsourcing transport to the robot

In order to gather goods in a warehouse, people often have to cover many kilometers a day. Driverless transport systems take over this arduous work in logistics. They automatically fetch the requested cardboard boxes and take them to a central point where the human workers can process the goods.

Assistant robot - The robot supports recovery

Robots in the form of assistant robots can promote faster healing and at the same time relieve the burden on nursing staff. For example, rehab robots can perform therapeutic movements that they have learned from a caregiver. Thus, lying patients can be mobilized without the caregiver having to lift heavy limbs themselves.