Choosing the Right Cobot

FANUC cobot

Origin of the term

Michael Peshkin, professor of mechanical engineering at Northwestern University in Illinois and his colleague Ed Colgate invented the concept of the cobot over 20 years ago. At the time, the robotics sector was focused on robot autonomy and not on cooperation with man. The two professors advocated that people should not be systematically excluded from the process because some tasks are better performed by man. On the other hand, tasks that are more difficult for man should be left to robots. The idea of man-machine collaboration was born.

Definition

Collaborative robots are a new generation of articulated robots with 6 or more axes designed to operate safely in an industrial environment shared with humans.

• They come in the form of a small lightweight articulated arm or double arm.
• Cobots are used to assemble parts and to lift and move objects. They are also suitable for packaging at the end of the production line.
• They always operate under the supervision of an operator.
• Most cobots handle parts with an average weight of between 5 and 100 kg. In the aeronautics sector, some cobots can lift up to 300 kg.
• They are equipped with sensors and cameras to give them an idea of their surrounding environment, detect human operators and avoid collisions.
• As they work closely with humans, they move more slowly than industrial robots and are programmed to stop if their arm encounters resistance.
• To ensure safety, for most cobots a simple tap on the hand is enough to start and stop it.

Universal Robot cobot

Cobots have significant advantages over conventional industrial robots:

• Their potential lies in their productivity and efficiency: they help humans in highly repetitive, difficult, painful and dangerous tasks. This means the human operator can concentrate on the most qualified tasks with the highest added value, which improves the final quality.
• They are quick to install and program.
• Unlike heavy and rigid industrial robots that can’t be moved, cobots can be moved by the operator from one task to another without needing to be reprogrammed.
• Cobots work without a protective barrier. Cages are often very expensive, so not requiring them reduces costs.
• Cobots are cheaper than conventional industrial robots (the cheapest ones start at €10,000) and can be suitable for low-budget companies that want to automate certain tasks.
• Implementing them allows for the preservation of the ergonomics of the workstation already in place.
• They are safer for working near humans.
• Cobots also have advantages over a fully automated system: they are more versatile and thus adapt to changes in production.

Cobots are less varied than other types of industrial robots. They are generally small and medium-sized articulated robots.

However, you must choose them according to specific criteria:

• the maximum payload;
• reach;
• the number of axes (usually 6 or 7, though some like the Yumi are combinations of several articulated arms and can reach up to 14 axes).

The table below summarizes the main types of technology currently available from the main cobots on the market as well as their principal applications.

ABB Robotics cobot

Cobots are suitable for any repetitive tasks, light applications and payloads not exceeding 100 kg (except in the aeronautics sector where loads can reach 300 kg).

Typical applications include:

• On assembly lines: screwing, gluing, welding tasks.
• On production lines: polishing tasks, laser marking, life cycle testing, packaging, palletization.
• On the machine: placing a part in a machine for milling for example.
• Pick-and-place: picks up parts from a bin and deposits them on a tray.
• Light applications: movement of a part by the robot and end of the process by the human.

Cobots are used in many sectors, from the automotive industry to consumer electronics, as well as in logistics, agriculture and medicine.

The automotive industry was the first to set up a man-machine collaboration:

• In 2013, BMW began deploying cobots on car door assembly lines.
• Also in 2013, Volkswagen started using cobots to install glow plugs in its engines.
• In 2015, Audi introduced cobots measuring 1.40 m high with two arms on its assembly lines in Germany.

In the aeronautics industry:

• Boeing has deployed cobots on its 777 assembly line in Seattle.
• Nextage, a semi-humanoid two-armed cobot designed by the Japanese firm Kawada, is used to assemble A380 components.

In the electronics sector:

• Cobots are used to perform assembly tasks, or life cycle tests.

KUKA cobot

Unlike conventional industrial robots, cobots are very easy to program.

• It is not necessary to write code. The included software is very intuitive, which does not mean that you do not have to learn to use the program first.
• Another option available for cobots is programming by learning: all you have to do is show the robot to teach it what to do.

Programming by learning is done directly at the workstation and using an application. To program a cobot, you must:

• Download the cobot application and create tasks in it.
• Then teach the cobot the movements you want it to perform by taking it directly by the hand, and recording them in the application.
• Then let the cobot do its job.
• Reprogram during production if necessary.

Although cobots are designed to work safely with human collaborators, they are still industrial robots. As such, they must comply with safety standards, like any other device operating in an industrial environment.

Since 2016, the ISO/TS 15066 standard has provided concrete guidelines for manufacturers and users of collaborative robots.

What does this standard outline?

• The standard does not exclude contact since cobots are brought into physical contact with humans.
• The standard defines cobot force and pressure thresholds.
• Safety is therefore not focused on collision avoidance but on the force and pressure that the operator can withstand when in contact with the cobot without being injured.

What are the thresholds?

• The standard provides thresholds for 29 body parts.
• The force threshold is 140 N at the chest.
• The pressure threshold for the sternum and pectoral muscles is 120 N/cm2 and 170 N/cm2.

KUKA mobile cobot

Mobile robotics is a new trend in industrial robotics:

• Autonomous or on a platform, mobile cobots represent the third robotic revolution.
• They are more flexible and can navigate in a factory without markings or magnets on the ground thanks to a laser guidance system.
• They are just as safe as static cobots and can work alongside humans.
• Mobile cobots already on the market include: OmniRob (KUKA), APAS robot (Bosch).

Cobots incorporating artificial intelligence are also a major trend for the future of the industry. Today, in order for a cobot to be able to perform a task it is necessary to program it by teaching it first. In the future, with AI, it will simply be a matter of showing a basic functionality to the cobot who will then be able to reproduce the task and even improve it with time and experience.

Manufacturers are also working on a language feature so that the cobot and the human will be able to speak to each other. KUKA is, for example, developing technology using NLP , neuro-linguistic programming.