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ROBOTICS Collaborative Robots - Sharing workspace alongside humans

Apr 18, 2019

With the rapid pace of automation and digitalisation within the global manufacturing sector, manufacturing units are increasingly adopting robotic solutions so as to enhance their workplace and help their workforce to embrace ‘smart’ technologies. This article explores the types and benefits of collaborative robots and the latest trends in robotics, which are aiding manufacturers in improving productivity by using robots to complement human skills.

Collaborative industrial robots are designed to perform tasks in collaboration with workers in industrial sectors. The International Federation of Robotics defines two types of robots designed for collaborative use: One group covers robots designed for collaborative use that comply with the International Organisation for Standards norm 10218-1, which specifies requirements and guidelines for the inherent safe design, protective measures and information for use of industrial robots. The other group covers robots designed for collaborative use that do not satisfy the requirements of ISO 10218-1. This does not imply that these robots are unsafe. They may follow different safety standards, for example, national or in-house standards.

There is considerable variance in the types of collaborative robots meeting the above specifications and the level of contact between robot and worker in collaborative applications. At one end of the technical spectrum are traditional industrial robots operating in a separate workspace that workers can enter periodically without having to shut off power to the robot and secure the production cell beforehand – a time-intensive procedure that can cost thousands of dollars per minute of machine downtime. The robot’s workspace can be fitted with sensors that detect human motion and ensure the robot works at very slow speeds or stops when a worker is within the designated workspace.

At the other end of the spectrum are industrial robots designed specifically to work alongside humans in a shared workspace. Often referred to as ‘cobots’, these robots are designed with a variety of technical features that ensure that they do not cause harm when a worker comes into direct contact, either deliberately or by accident. These features include lightweight materials, rounded contours, padding, ‘skins’ (padding with embedded sensors) and sensors at the robot base or joints that measure and control force and speed and ensure that these do not exceed defined thresholds, if contact occurs.

Ensuring safety

Like any other piece of industrial machinery, collaborative robots must be safe. The International Organisation for Standardisation (ISO) has developed standards for robots operating in four types of collaborative mode. Compliance with these standards means that the robot can, in principle, be used safely. However, a safe robot does not guarantee a safe collaborative application in practice. A process in which a safe cobot wields a sharp tool is unsafe, no matter how slowly the cobot operates. End-users must conduct a risk assessment of the intended application to be certain that they meet the legally binding standards for health and safety at work in their country. The assessment covers the entire application, including the workspace, the robot, end-effector, tools, workpieces and other elements such as, cabling and lighting, that could pose hazards.

Types of human-industrial robot collaboration

Human-industrial robot collaboration can range from a shared workspace with no direct human-robot contact or task synchronisation to a robot that adjusts its motion in real-time to the motion of an individual human worker. Currently, IFR members find that the most common collaborative robot applications are shared workspace applications, where robot and employee work alongside each other, completing tasks sequentially. Often, the robot performs tasks that are either tedious or unergonomic — from lifting heavy parts to performing repetitive tasks such as, tightening screws.

Applications in which the robot responds in real-time to the motion of a worker (altering the angle of the gripper to match the angle at which a worker presents a part, for example) are the most technically challenging. Since the robot needs to adjust to the motion of the worker, its movements are not completely predictable and therefore, the end-user must be sure that the full parametres of its potential scope of motion meet safety requirements. Examples of responsive collaboration in industrial settings are unlikely to appear soon in most manufacturing sectors, which rely on precision and repeatability to achieve productivity gains.

Benefits of collaborative robots

Collaborative robots provide an economically-viable entrypoint to robotic automation. They can be used to automate parts of a production line with minimal changes to the rest of the line, providing companies that have not yet automated production processes, such as, small-to-medium-sized manufacturers, an entry to the productivity and quality improvements offered by robots. For companies, such as, automotive manufacturers that have already automated the production of car bodies, the additional use of collaborative robots offers the opportunity to support workers in completing final assembly tasks that are often the source of chronic back injuries. Collaborative applications enable manufacturers to automate parts of processes that are tedious for humans — from fetching parts and feeding machines to quality inspection, which is hard for humans to do consistently over long periods of time.

System integration

In the past, systems integrators and internal robot experts have been required to install programs and operate industrial robots. Programming interfaces are now increasingly intuitive in both traditional robots and newer cobots. Systems integration experts are still needed for complex applications and those requiring a re-design of the entire production process. For simpler, stand-alone applications, workers with minimal robot training can now easily re-deploy the robot to a new task. This is particularly important for manufacturers that operate short production runs and need to be able to quickly re-task the robot for a new run. Cobots are usually lightweight and can be easily moved around the factory. They generally take up less factory floor space — a significant cost factor for manufacturers. This combination of features addresses a market of end-users that are new to robotic automation and do not have, nor plan to gain, expert automation capability.

Industrial robots often operate from a fixed mounting, but there is demand for mobile industrial robots that combine a mobile base and a (collaborative) robot. These robots can, for example, carry materials from one workstation and unload them or feed a machine at a second workstation.

The right choice of robot – traditional or collaborative – is determined by the intended application. When speed and absolute precision are the primary automation criteria, it is unlikely that any form of collaborative application will be economically viable. In this case, a traditional, fenced industrial robot is — and will remain — the preferred choice. If the part being manipulated could be dangerous when in motion (for example, due to sharp edges), some form of fencing will be required. This applies even for cobots that stop on contact. Another factor influencing economic viability is the extent to which the robot must be integrated with other machines in a process. The more integration needed, the higher the cost of the robot installation.

Collaborative industrial robots are tools to support employees in their work, relieving them of many heavy, unergonomic and tedious tasks, such as, holding a heavy part steady in the required position for a worker to fit screws. However, there are still many tasks that are easy for humans but hard to automate, for instance, dealing with unsorted parts, and irregular or flexible shapes. Finishing applications, such as, polishing and grinding applications that require continuous fine-tuning of pressure applied to the surface are also difficult to automate cost-efficiently. Collaborative robotics enables manufacturers to improve productivity by using robots to complement human skills.

Future trends in collaborative robotics

The market for collaborative robots is still in its infancy. Endusers and systems integrators are still gaining experience on what works and what does not in the design and implementation of collaborative applications. Technology developments in sensors and grippers hold promise for expanding the range of actions that the robot end-effector can perform. Programming interfaces will continue to become more intuitive, not just for cobots, but also for traditional industrial robots.

Courtesy: International Federation of Robotics

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  • Collaborative robots provide an economically-viable entry-point to robotic automation

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