What Are Collaborative Robots (Cobots) and How Do They Work?

Collaborative robots, often called cobots (from "collaborative robot"), are industrial robots designed to work safely alongside humans within the same workspace. Unlike classical robotic installations that are usually housed behind safety barriers, cobots can perform certain tasks right next to an operator. This proximity is possible thanks to limitations on speed and force, advanced sensors, motion control, and emergency stop systems. However, the absence of a safety cage does not automatically guarantee the safety of every cobot-much depends on the specific task, the end-of-arm tooling, and the overall workplace design.

What Are Collaborative Robots and How Do They Differ from Traditional Industrial Robots?

A collaborative robot is a robotic manipulator engineered for tasks where humans and machines share the same working area. For example, an operator might place a part in a fixture, after which the cobot tightens fasteners, moves blanks, or performs repetitive movements. The key difference between cobots and traditional industrial robots goes beyond size. Classic industrial robots often operate at high speeds, handle heavy loads, and can generate dangerous force upon collision, which is why they are typically separated from people using barriers, light curtains, or other safety measures.

To learn more about how traditional automation is structured and the tasks solved by industrial manipulators, see the article: Industrial Robots and Automation: How Modern Manufacturing Is Changing.

Cobots are designed for direct human interaction. Their control systems can limit movement speed, actuator force, and permissible torque. If the manipulator encounters an obstacle or detects abnormal load, it can rapidly halt movement. Many models use force and torque sensors installed in actuators or joints, constantly analyzing resistance. If this resistance exceeds safe limits, the system interprets it as potential contact and stops the robot immediately.

Another benefit of cobots is their relatively simple programming. For some tasks, an operator can manually guide the manipulator along the desired trajectory and save key positions, reducing setup time-especially useful for productions with frequent product changes or small batches.

It's important to note that the line between an industrial robot and a cobot isn't always defined by the model. The same manipulator can work in collaborative mode with limited speed and properly configured safety systems, or, for other tasks, may require full fencing-especially if equipped with sharp tools or tasked with moving heavy metal parts. In these cases, the risk is determined by the entire robotic cell, not just the robot itself.

How Collaborative Robots Work

At the heart of every cobot is a multi-axis manipulator with electric drives, a controller, and a suite of sensors. The controller receives data on joint positions and calculates the required movements to position the tool at a specified point. Joint positions are tracked by encoders-sensors that measure the rotational angle of each actuator-allowing the system to precisely replicate programmed trajectories. The more degrees of freedom a robot has, the more complex its possible movements within confined spaces.

Force and torque sensors play a crucial role, allowing the controller to monitor resistance during motion. For instance, when inserting a part into a hole, the system can detect increased resistance and adjust the position, rather than forcing the part in.

The controller also monitors speed, acceleration, and load on the actuators. In collaborative mode, these parameters are limited to ensure the robot doesn't exceed defined thresholds-a critical safety feature when an operator is nearby.

Cobots can be programmed traditionally by setting coordinates, action sequences, and operation conditions, but a more intuitive "teach-by-demonstration" approach is also common. Here, the operator physically guides the robot through the desired positions, which the system records for future automatic execution. This method is especially convenient in environments where the robot frequently switches between tasks-operators can quickly adjust the trajectory, gripping parameters, or action sequence, minimizing downtime.

The manipulator's end effector can be a gripper, screwdriver, welding tool, suction cup, camera, or other module, greatly influencing the capabilities of the entire setup. The cobot ensures precise tool positioning, while the attached equipment performs the specific task.

During operation, the robot continuously cycles through its control loop: determining position, processing sensor data, calculating the next move, and checking safety limits. This allows the cobot not just to follow pre-recorded paths, but to actively monitor and respond to its environment in real time.

How Collaborative Robot Safety Is Achieved

Safety in collaborative robots is ensured not by a single sensor, but through a combination of software restrictions, actuator monitoring, and external surveillance systems. The cobot must constantly be aware of its speed, applied force, and whether its actions stay within set parameters.

One fundamental safety mechanism is force and power limitation. If the manipulator collides with a person or an obstacle, the system detects the unexpected resistance. If it exceeds safe values, the robot either stops or reduces force to minimize injury risk.

Speed is also controlled-when a person is nearby, the cobot operates slower than a standard industrial robot. The higher the speed and mass of a moving part, the greater the collision energy, so movement parameters are tailored to each operation.

To monitor the area around the robot, cameras, laser scanners, and other presence sensors may be used, detecting human approach before physical contact. Depending on the settings, the robot may first slow down and then stop completely as a person enters critical zones.

Another protective measure is software-defined work zones. The controller can be programmed with boundaries that the manipulator must not cross, preventing the robot from moving toward walkways, operator stations, or adjacent equipment.

The system also monitors actuator positions and statuses. If any axis moves unexpectedly, experiences excessive load, or a sensor error occurs, the robot can initiate an emergency stop, responding not only to collisions but also to equipment faults.

However, a safe manipulator alone does not guarantee a safe robotic cell. The end effector must also be considered-a gripper with soft jaws and a lightweight plastic part is much less risky than a sharp tool, hot workpiece, or heavy metal object.

That's why a comprehensive risk assessment is performed before deploying a cobot: collision and pinch points, load weights, movement speeds, tooling used, and likelihood of human presence in various work zone areas are all evaluated. Only a thorough risk assessment determines whether the robot can truly operate without additional physical barriers.

Why Cobots Can Operate Without Protective Barriers

Traditional industrial robots are often separated from people by safety fencing because of their ability to move at high speeds and handle heavy objects-if a person accidentally enters the workspace, the robot may not be able to stop in time to prevent a collision.

Collaborative robots are designed for a different scenario. Their movements can be limited by speed, force, and workspace boundaries, while safety systems monitor human presence. This makes it possible, for some tasks, for a cobot to operate without the familiar metal cage.

One method is force and power limitation-the manipulator moves with parameters ensuring that any contact does not result in dangerous impact. If a collision or excessive force is detected, the system halts movement.

Another approach involves distance monitoring. Cameras, laser scanners, or other sensors create controlled zones around the robot. While people are distant, the cobot works quickly; as an operator approaches, speed is reduced, and when entering a critical area, the robot stops entirely.

Sometimes, collaboration is organized through task alternation: the human completes their part, then the robot continues. The system ensures that hazardous movements only begin when the operator has vacated the relevant zone.

The absence of physical barriers makes workspaces more compact and interaction with equipment easier-operators don't need to open safety doors to swap parts, reposition blanks, or inspect results.

However, cobots cannot always be used without barriers. If the robot handles heavy items, sharp tools, high temperatures, or inherently dangerous equipment, built-in safety features alone may be insufficient.

Thus, the phrase "cobot operates without protective barriers" describes only one possible scenario. The decision is made for the entire robotic cell, accounting for speed, tooling, moved objects, workplace layout, and how close a person can get to moving parts.

Where Collaborative Robots Are Used and Why Industry Needs Them

Cobots are especially valuable where full automation is impractical, but repetitive tasks can be delegated to machines. Humans remain nearby, handling tasks that require judgment, flexibility, or manual skills.

One common scenario is assembly. A cobot can supply parts, hold components in position, tighten fasteners, or perform repetitive motions, while the operator handles more complex processes and quality control.

Another application is machine tending-robots load blanks into machines, remove finished parts, and supply the next item. This automates monotonous tasks without a complete production line overhaul.

Cobots are also used for packaging, sorting, and moving products. They can pick items from a conveyor, pack them into boxes, or transfer goods between workstations. Equipped with cameras and machine vision, cobots can even identify part types and positions.

In quality control, cobots provide consistent movement of cameras, measuring devices, and sensors along set paths, enabling automated inspection of surfaces, dimensions, or assembly accuracy.

The advantages of cobots are particularly evident in small-batch production. Classic automated lines are efficient for long runs of identical products, but cobots are easier to reconfigure for new tasks or move to different workstations.

Their compactness also allows deployment where space is too limited for large robotic cells. In suitable scenarios, the lack of heavy fencing further reduces the installation footprint and simplifies operator access.

However, cobots do not replace traditional industrial robots in every situation. The speed and force limitations necessary for safe human collaboration reduce their overall throughput. For rapid handling of heavy items or tasks requiring maximum cycle speed, classic industrial robots behind barriers are often more efficient.

Therefore, cobots are particularly useful not where people can be fully replaced, but where it is most advantageous to share work between humans and machines. Robots take on repetitive, physically demanding, and monotonous tasks, while operators focus on those requiring flexibility and decision-making.

Conclusion

Collaborative robots make automation more flexible: rather than fully isolating machines from people, they enable safe teamwork in shared spaces. This is achieved through speed and force limits, actuator position monitoring, force sensors, human detection systems, and software-defined work zones.

However, a cobot's design alone does not guarantee safety. Consideration must be given to the installed tooling, part weights, movement speeds, and specifics of each operation. Only a thorough assessment of the entire robotic system can determine if protective barriers can be safely omitted.

Cobots are especially useful for frequent production changeovers, automating small batches, or delegating repetitive tasks to machines while keeping humans in the process. For high-speed, heavy-duty operations, traditional industrial robots remain the better choice.