What Are Collaborative Robots (Cobots)?

What is the definition of a Cobot?

Labor shortages in the United States have become a significant headache for many years. Various industries, including manufacturing, construction, healthcare, and hospitality, are experiencing difficulties in finding and retaining skilled workers. The welding industry is not immune: AWS projects 360,000 additional welding positions will be needed by 2027.

The challenge of hiring and retaining welders is substantial. Developing the pipeline of talent is a long-term effort that requires the coordination of industry, government, and education. In the short term, manufacturers are reaching for automated solutions to help them bridge the gap. One technology option that can help to address the critical labor shortage is using collaborative robots.

Through the course of this blog, you will gain an understanding of what cobots are, where they are used, the components of a cobot system, and the crucial aspect of safety in cobots.

Let’s start with a standard definition of a collaborative robot:

What is a cobot?

The term 'cobot' is short for 'collaborative robot'. Cobots are a subset of programmable machines designed to safely perform tasks within a human environment. Cobots can work next to people (or in a shared workspace) without modifications to the work area.
 
While cobots work beside humans to deliver safety, flexibility, and ease of use for small-scale tasks, traditional robots often perform hazardous or repetitive often large-scale tasks independent of humans.

Traditional Robots vs Cobots: The Differences

While all cobots are robots, not all robots can be classified as cobots. Non-collaborative robots that operate in heavy-duty, rugged environments are often referred to as “traditional robots”. These robots employ large articulated arms that are used in the automotive industry, working around a car chassis without a single person nearby. 

Applications that use traditional robots are high-speed and/or have large payloads. These robots rely on an external safety structure, which includes a physical barrier to prevent humans from entering while the robot is working.

Cobots, on the other hand, are designed with safety features integrated into the robot. Cobots use sensors to monitor the motion, speed, force, and power of the cobot relative to a person’s proximity.

Figure 1: Traditional Robot and Cobot in Operation

The Four Modes of Human-Cobot Interaction

Under the ISO 10218 Standards, human work performed alongside cobots is segmented into four main categories. These have distinct characteristics which make each one suitable for different kinds of tasks within the manufacturing industry. Some systems leverage more than one of these techniques.

1. Safety Monitored Stop: Safety Monitored Stop cobots cease operation humans come into their proximity. They are primarily utilized in a setting where interaction is minimal, making them ideal for operations where the load or the speed of the robot may pose a risk.
2. Hand Guiding: Equipped with a unique type of sensor, hand-guiding cobots allow their human counterparts to manually guide their movements. These are typically used for tasks that require intricate operations, for example, drilling holes or opening doors. This approach is a unique benefit cobots add to the manufacturing process.
3. Speed and Separation Monitoring: As the name suggests, cobots control their speed and halt if something gets too close. Speed and Separation Monitoring cobots are usually employed in large-scale operation centers.
4. Power and Force Limiting: As one of the most common designs, Power and Force Limiting cobots use a series of sensors to monitor their force and recoil if they experience resistance. These cobots are especially prevalent in assembly lines, packing areas, and pick-and-place operations.

Cobot Applications: Where are cobots used?

Cobots have found their utility spanning across an impressive range of industries and applications. Here are a few examples pulled from the thousands of use cases:

Industry	Cobot Application
Automotive	Screw and fastener installation, spray painting, welding, soldering
Manufacturing	Welding, gluing/sealing, machine loading/unloading, sanding/polishing
Healthcare	Assisting surgical procedures, loading/unloading, bin picking
Agriculture	Fruit picking, targeted weed control, animal husbandry
Consumer Goods	Palletizing, product placement, quality testing/inspection

The above applications are just a glimpse of actual use cases. For example, welding applications include arc welding, MIG, TIG, laser, plasma, ultrasonic, and spot welding.

What makes up a cobot system?

Robot

A cobot system is made up of the following parts: the robot arm, controller, teach pendant, end-effectors, vision systems, and sensors. The robot arm is the most visible component of a collaborative robot system and is analogous to the human arm. Built with several joints and segments, the robot arm mimics the capabilities of a human arm. Its primary role is to perform tasks that require precision and endurance, working on repetitive operations. The robot arm has torque sensors inside of the joints which can be leveraged as a part of the safety system. The robot arm is a programmable component, run by the system's controller.

Controller

If we continue using the analogy of the human body, the controller is the brain. It receives inputs from various sensors and sends commands to the robot arm, guiding its movement and actions. Since the controller commands the robot, a human must be able to talk to the controller to provide its programming. The human interface with the controller is through the teach pendant.

Teach Pendant

The teach pendant is a crucial component of a cobot that interacts with humans. This handheld device is used to manually control, program, test, and troubleshoot the cobot. By inputting commands through the teach pendant, operators can “teach” the robot how to perform specific tasks. In a welding operation, for example, the operator can use the pendant to guide the robot through a weld, saving the path and actions for the cobot to replicate.

End Effectors

End effectors are the “hands” of the robot. There are many different types of end effectors designed to execute specific tasks. For example, the welding torch would be the end effector for the welding cobot. End effectors can be switched out, allowing the cobot to perform a wide range of tasks.

Vision System (optional)

In some applications having additional visibility is needed. Vision systems can be the eyes of the robot but are not required for every application. These systems involve cameras that capture the images and software that interprets them. The cobot utilizes this information to adjust its actions, especially if the part position is variable and is positioned differently each time. These inputs contribute to the adaptive nature of cobots, enabling them to operate in dynamic, ever-changing environments. 

Sensors (optional)

External sensors are optional components that could be used along with the force sensors integrated into the cobot arm. Similar to the vision system, these sensors are not required for every application. A detailed risk assessment will help you determine if any additional sensors are needed for the application. Fabricators can also leverage their integrator’s knowledge as they design their collaborative robot system.

Figure 2: Diagram of cobot system and components

How safe is a cobot?

Cobots are designed with safety in mind, however, it remains essential for the installer to plan for all safety measures. All robot installations must conduct a thorough risk assessment, which is a formal process to ensure the robot is safe to use in the facility. We touch on a risk assessment in our blog article called “Cobot Welding”. A risk assessment is a comprehensive document that quantifies the hazards and selected solutions.

ISO 10218 is a set of international standards that specifically address the safety requirements for industrial robots. It provides guidelines and requirements for the design, manufacture, and integration of robots in various industries.

For cobots, collaborative robot safety standards ISO-10218 and TS-15066 apply. ISO-10218 describes safety requirements for industrial robots, while TS-15066 supplements this standard with guidance for industrial-only cobot systems and workplace safety. The ISO 10218 standard is divided into two parts: ISO 10218-1 and ISO 10218-2. ISO 10218-1 focuses on the robot itself, while ISO 10218-2 focuses on the robot system and integration.

These standards ensure that robots are designed and used safely, protecting both the operators and the surrounding environment. To find ISO 10218, you can visit the International Organization for Standardization (ISO) website or contact your local standards organization for more information.
 
OSHA outlines some examples and best practices for conducting an effective risk assessment (RA). For each action (task) there is an associated hazard, calculated risk level, documented safety solution, and new risk level. The output of the assessment is the required safety function and the functional risk reduction measures for each function. An excerpt from OSHA below is an example of a Risk Assessment.

Figure 3: Risk Assessment Example

Keep in mind that risk assessments should be periodically reviewed and validated. A risk assessment will show the solution but will not capture the status of that action. This is why a task list (or action list) should be an output of the RA. The task list will assign a person and a due date to each task. The task list should be reviewed with scheduled frequency to ensure all actions are completed on time.

A successful outcome of a Risk Assessment is a safely installed cobot system that is ready for use.

Next Steps/More Information

We touched on a lot of topics throughout this blog article, including what cobots are, where they are used, the components of a cobot system, and cobot safety. If you are looking for more information, we have additional articles available on our ESAB University, or contact us for answers to specific questions.