What Are Collaborative Robots?

Collaborative robots, widely known as cobots, are robots designed to share a workspace with people and to operate safely without the physical guarding that separates conventional industrial robots from human workers. They are distinguished less by their mechanical form, which is usually a lightweight articulated arm, than by the control and sensing behavior that lets them detect contact, limit the force they can apply, and slow or stop as a person approaches. The category emerged from research on intrinsically safe manipulators in the 1990s and became commercially significant in the 2010s, when torque-sensing joints and certified safety controllers made close-proximity operation practical on a factory floor.

Collaboration in this sense is a property of the whole application, not of the robot alone. A cobot arm mounted with a sharp tool, moving at speed, or handling a heavy payload may still require fencing, while the same arm running a light assembly task at reduced speed may need none. The relevant risk assessment therefore covers the robot, the end effector, the workpiece, and the layout together.

Collaborative Operating Modes

Safety practice for these systems is organized around four collaborative operating modes defined in ISO/TS 15066, the technical specification that supplements the ISO 10218 industrial robot safety standards and whose content has since been folded into the 2025 revision of ISO 10218-2. Safety-rated monitored stop halts robot motion whenever an operator enters the shared space and resumes automatically when the space clears. Hand guiding lets an operator move the robot directly through a force-sensing device. Speed and separation monitoring uses external sensing to maintain a protective separation distance that shrinks or grows with relative speed. Power and force limiting caps the energy that can be transferred in a contact event, using biomechanical limits tabulated for 29 body regions so that unintended contact stays below the onset of pain.

Mechanical Design and Compliant Control

Meeting those limits shapes the hardware. Cobot arms use low moving mass, rounded surfaces without pinch points, and joint-level torque sensors or current-based estimation that let the controller infer external forces without a dedicated force-torque sensor at the wrist. Control laws are typically compliant rather than purely positional: impedance and admittance schemes make the arm behave like a programmable spring and damper, so it yields on contact instead of resisting. Research on variable impedance control derived from ISO/TS 15066 limits shows how the allowable force and pressure values can be mapped directly onto controller gains and speed limits, tightening compliance where a collision would be most severe. Redundant safety-rated encoders and dual-channel controllers ensure that a single fault does not defeat the limit.

Performance Assessment and Programming

Because a cobot trades peak speed and payload for proximity, its economic case depends on how quickly it can be deployed and reconfigured. Hand-guided teaching, graphical task-level programming, and libraries of parameterized skills such as pick, insert, and screw-drive replace the text-based teach pendant workflows of traditional industrial robots. Measuring what these systems actually deliver is an active metrology problem, and the NIST program on the performance of collaborative robot systems develops test methods and metrics for contact safety, grasping, agility, and human-aware behavior so that manufacturers can compare systems on evidence rather than on specification sheets. Typical measures include cycle time under speed and separation monitoring, positional repeatability, and the force and pressure produced in controlled collision tests.

Applications

Collaborative robots have applications across a range of sectors, including:

• Small-batch and mixed-model assembly in electronics and automotive supply chains
• Machine tending, palletizing, and packaging in small and medium enterprises
• Laboratory automation, sample handling, and pharmacy compounding
• Quality inspection and metrology tasks that combine a camera with a moving arm
• Surgical assistance and rehabilitation robotics, where physical human contact is intrinsic
• Agricultural harvesting and food handling in unstructured environments