Industrial automation and robotics are nothing new within manufacturing. However, a new paradigm is emerging which blends manual and robotic activities. Where traditional automation solutions have been isolated from human workforce for safety reasons, new sensorised and aware robotic systems – or collaborative robotic systems (Cobotics) - are now becoming common place.
A collaborative robot is one that has features which make it appropriate for collaborative
applications (applications in which a human and robot operate collaboratively on a job) or coexistent applications (ones in which the human and robot share a space but do not necessarily directly interact).
Teachability, reconfigurability through programming, small footprint, and inherent safety are typical features of these robotic systems. Safety considerations are not exclusively limited to the robot itself but also comprise end effectors, supporting sensors and equipment that complement the robot functionalities although occasionally may limit its flexibility.
Figure 1 - Definition of terms according to ISO 8373:2012
Benefits and limitations of cobotics in manufacturing are discussed as follows.
Human reaction and cognition skills can now be combined with robots’ ability to perform repetitive tasks through the implementation of appropriate safety measures and mechanisms. For instance, ISO/TS 15066:2016 outlines four fundamental safety measures:
- Safety-rated monitored stop - the robot motion is stopped before an operator enters the collaborative workspace to interact with the robot system and complete a task. Motion resumes after the operator has exited without any additional intervention.
- Hand-guiding operation method - the operator uses a hand-operated device to transmit motion commands to the robot system.
- Speed and separation monitoring operation method - risk reduction is achieved by maintaining at least the protective separation distance between operator and robot at all times.
- Power and Force limiting operation method – this requires specifically designed robot systems (i.e. collaborative robot) which allow physical contact with the operator, either intentionally or unintentionally. Such robots are designed to dissipate forces in case of impact and are programmed to stop when abnormal forces are detected.
Job sharing/reallocation of tasks
With the move from hazard removal (i.e. avoid any type of contact between robots and operators) to risk reduction, comes the opportunity for human and machine to share tasks, allowing increased productivity and better workforce support.
Repetitive tasks that are not suitable for traditional automation technology can still benefit from cobotics systems; for instance, a sub-set of tasks within a complex process can be easily allocated
to a robot and tasks requiring cognitive, reaction and fine motor skills can be allocated to human operators, often using a collaborative approach. This will support productivity improvements and reduce operators’ health and safety challenges, including the risk of ergonomic injuries.
Human-Machine interaction: Design
The collaboration aspect between robotic systems and operators obviously introduces additional complexity to automation design. Mechatronics skills are not enough in robotic design anymore, as a human-centric design approach becomes critical in terms of ensuring safety and ease-of-use. As an example, in the case of force-limited robots, contact between human and machine is allowed; this means that the design must consider the possibility of this impact and provide new communication channels to enable more intuitive, less intimidating and safer interaction. Some emerging design trends in this new category of robot therefore include rounder shapes and hidden joints, allowing the force of impact to be spread over a bigger surface and thus reducing the pressure applied on the object of contact. Some robot designs also include a soft external skin or even a sensitive skin composed of tactile sensors. Sensors and smart technologies are often added to make the robotic system more “people-aware”, as well as location/context-aware. These new sources of data can be linked through IIoT systems to be part of management systems or optimisation algorithms, which ultimately leads to smarter robotic systems.
The high flexibility of collaborative robots enabled by their ease of programming and small footprint, provides a key opportunity in process automation. This flexibility means that a robot system is not limited to one task and can be repurposed quickly for various tasks according to the needs of the plant floor. This also reduces investment risks since, if the system does not prove fit for purpose, it can be moved to deliver value elsewhere.
Some broadly applicable limitations of current collaborative robots can be enunciated as follows.
Due to their design, force-limited robots are limited in:
- Payload – Majority ranges between 2 and 10kg (FANUC 35kg, COMAU 110kg)
- Reach – Majority ranges between 500 and 1,300mm (FANUC 1813mm, COMAU 2210mm)
- Speed – Limited by the risk assessment of the application.
Moreover, end-of-arm tooling for collaborative application still lacks flexibility (needs of increased dexterity, flexible gripping mechanisms, additional integrated features and sensors). Finally, collaborative robotic applications still need to fully adapt to humans, unexpected events, and evolution of the environment.
Alongside technical limitations, introduction challenges related to potential cultural resistance of operators (i.e. job security concerns) to collaborate with robotic systems should also be considered. Developing a vast range of skills, from cognitive psychology and sensorisation, to user interface development and robotic programming, can be used to remove any operator’s fear and rejection for this new powerful and innovative technology.
Collaborative robotics seeks to change the way we see automation, allowing extraction of value from the joint capabilities of human and robot working in collaboration with no safeguarded space. Their ease-of-use places cobotic systems as valuable flexible assistants, where highly manual processes are still source of many chronic conditions.
However, challenges such as the lack of fully developed authoritative information and standards, leading to a lack of understanding of risk management, are driving hesitation when it comes to cobotics implementations.
To tackle those challenges, and to enable businesses to implement the technology with confidence and with maximum value delivery, several skills can be developed, such as:
- human and process understanding.
- human/machine interface and communication.
- collaborative robotics programming.
- active involvement in National Steering Committees and international standards groups.
- and collaboration with research centres specialised in cobotics