Collaborative Robots (Cobots): Working Side by Side With Humans
Traditional Industrial Robots
A traditional industrial robot is a programmable machine that performs repetitive tasks with high precision and speed in an environment isolated from humans. It has been used since the 1960s in automotive and electronics manufacturing.
Key Characteristics
- Speed and Power: Moves at high speeds and lifts loads up to hundreds of kilograms
- Precision: Repeatability down to 0.01 mm
- Isolation: Operates inside safety cages away from humans
- Programming: Requires specialized programmers and manufacturer-specific languages
- Cost: High investment including the robot, cage, programming, and integration
Traditional Robot Applications
- Welding: Spot and arc welding in automotive manufacturing
- Painting: Uniform and precise paint spraying
- Heavy Assembly: Installing large and heavy components
- Material Handling: Moving parts between workstations
- Packaging: High-speed box packing
Limitations of Traditional Robots
- Large floor space required for safety cages
- Difficult to reprogram for new tasks
- Cannot collaborate directly with workers
- High integration costs make them impractical for small factories
Collaborative Robots (Cobots): What Is Different?
A collaborative robot (Cobot) is specifically designed to work side by side with humans in the same space without the need for safety cages.
How Does It Differ From a Traditional Robot?
| Feature | Traditional Robot | Cobot |
|---|---|---|
| Work Environment | Isolated in a cage | Directly beside the worker |
| Maximum Speed | Very high | Limited for safety (typically < 1.5 m/s) |
| Payload | Up to 1000+ kg | Typically 3-25 kg |
| Programming | Specialized and complex | Simple (drag-and-drop or hand guiding) |
| Cost | $50,000-$500,000+ | $15,000-$75,000 |
| Deployment Time | Weeks to months | Hours to days |
| Flexibility | Usually one task | Easy to relocate and redeploy |
Leading Cobot Manufacturers
- Universal Robots (UR): Market leader (UR3e, UR5e, UR10e, UR16e, UR20, UR30)
- FANUC: CRX series for collaborative applications
- ABB: GoFa and SWIFTI series
- KUKA: LBR iiwa series
Safety in Collaborative Robot Environments
Safety is the fundamental differentiator between cobots and traditional robots. It is governed by the ISO/TS 15066 standard.
The Four Collaborative Operation Methods
1. Safety-Rated Monitored Stop
- The robot stops when a person enters the work area
- Resumes operation when the person leaves
- Suitable for tasks that do not require continuous interaction
2. Hand Guiding
- The operator physically moves the robot to teach it a path
- Used for easily programming new trajectories
- An enable button must be continuously pressed
3. Speed and Separation Monitoring
- The robot slows down as a person approaches
- Stops if the person crosses the minimum safety distance
- Requires proximity sensors or 3D cameras
4. Power and Force Limiting
- The robot is mechanically designed to limit maximum force on contact
- Even if it collides with a person, the force does not cause injury
- The most common method in modern cobots
Programming Cobots: Teach by Demonstration
One of the greatest advantages of cobots is ease of programming. You do not need a robotics engineer to program a new task.
Hand Teaching (Teach Mode)
- Press the teach button on the robot
- Grasp the robot arm and manually move it to the desired points
- Record each point with a button press
- The robot repeats the path with precision
Visual Programming
- Drag-and-drop interface on a tablet
- Ready-made programming blocks: move, grip, wait, repeat
- Simple conditional logic: if the sensor detects a part, grasp it
- No code writing required
Script Programming
- For complex tasks beyond visual programming capabilities
- URScript language for Universal Robots
- Integrates with vision systems and external sensors
Cobot Applications on Assembly Lines
Machine Tending
- Loading parts into a CNC machine and unloading them after machining
- Freeing the operator for higher-value tasks
Inspection and Testing
- Checking part dimensions using a camera mounted on the robot
- Functional testing by connecting cables or pressing buttons
Light Assembly
- Installing screws and fasteners with precise torque
- Inserting components into circuit boards
Dispensing
- Applying adhesive or sealant along a precise path
- Quantity and path consistency superior to manual work
Pick and Place
- Moving parts from a conveyor to a workstation
- Sorting products by type or size
Practical Example: Adding a Cobot to a Quality Inspection Station
Let us add a collaborative robot to a quality inspection station in an electronics factory:
Current Problem
- A worker visually inspects circuit boards for 8 hours
- Fatigue causes missed defects, especially during long shifts
- Inspection rate: 120 boards per hour
Proposed Solution
- Cobot: Universal Robots UR5e with a machine vision camera
- Task: Pick up the board from the conveyor, present it to the camera, sort it (pass/fail)
Implementation Steps
- Mount the cobot next to the conveyor (no cage needed)
- Install an inspection camera on the robot wrist
- Teach the robot pick-up and sorting points (via hand guiding)
- Connect inspection results to the MES system
- Train the operator on supervision and restart procedures
Results
- Inspection rate increased to 200 boards per hour
- Defect detection rate improved from 95% to 99.5%
- The worker transitioned to analyzing defect causes instead of routine inspection
Summary
Collaborative robots represent a major shift in factory automation, especially for small and medium enterprises. They stand out from traditional robots through the ability to safely work alongside humans, ease of programming, and lower cost. The ISO/TS 15066 standard defines safe operating methods. Applications range from machine tending to inspection and assembly. Start with a single station that has a repetitive and simple task, and measure the return on investment before scaling up.