Cobots, or collaborative robots, are specifically designed with advanced safety features to enable them to work alongside humans without traditional safety barriers. These features are guided by international standards such as ISO 10218 and ISO/TS 15066, which detail the requirements for safe human-robot interaction.
Here are the key safety features and collaborative operation modes that cobots employ for human collaboration:
1. Collaborative Operation Modes
The ISO/TS 15066 technical specification (now largely incorporated into ISO 10218:2025) outlines four primary types of collaborative operation, each with distinct safety mechanisms:
Power and Force Limiting (PFL): In this mode, the cobot's design and control systems inherently limit the force and torque it can exert. This ensures that if incidental contact occurs, it does not result in pain or injury to a human. Cobots achieve this through low inertia, limited speeds, and sensitive force/torque sensors that detect contact and trigger an immediate stop if predefined limits are exceeded.
Speed and Separation Monitoring (SSM): This function allows humans and robots to work in the same area while maintaining a safe distance. Sensors (like safety scanners or light curtains) continuously monitor the distance between the human and the cobot. If a human approaches too closely, the cobot will automatically slow down or come to a complete stop, resuming full speed only when the area is clear.
Safety-Rated Monitored Stop: Also known as a safety-rated soft stop, this feature ensures that the robot stops its movement when a human enters its collaborative workspace. The robot remains powered and active, allowing for quick restart once the human has left the designated area, which is useful for tasks requiring human intervention or adjustments.
Hand Guiding: This mode allows an operator to directly control or move the cobot manually, often used for teaching the robot new paths or tasks. During hand guiding, the cobot's force and speed are monitored to ensure safety, and it can be easily programmed without extensive coding knowledge.
2. Integrated Safety Features
Beyond the operational modes, cobots incorporate several inherent design and technological features to enhance safety:
Force and Torque Sensors: These advanced sensors are crucial for PFL, enabling cobots to detect and respond to external forces from human interaction. They allow the cobot to apply appropriate force levels or stop if unexpected resistance is met.
Collision Detection: Integrated collision detection systems allow cobots to identify and react to unexpected obstacles or collisions in their workspace. Upon detection, the cobot can swiftly stop or adjust its movements to prevent accidents and minimize injury risk.
Safe by Design Principles: Cobots are often designed with smooth, rounded edges and minimized pinch points to reduce the risk of injury during accidental contact. They also typically have smaller, lighter arms and handle smaller payloads compared to traditional industrial robots, which reduces the potential for harm in the event of a collision.
Emergency Stop Buttons: All cobot systems are equipped with easily accessible emergency stop buttons that can immediately halt all operations in case of an emergency.
Speed and Position Monitoring: Cobots continuously monitor their own speed and position to operate within safe parameters and maintain safe distances from human workers.
Safety-rated Soft Robotics: Some cobots utilize flexible materials and compliant mechanisms that inherently reduce injury risk upon contact.
3. Regulatory Standards and Risk Assessment
The implementation of these safety features is heavily influenced by international standards. The ISO 10218-1 and ISO 10218-2 standards specify safety requirements for industrial robots, with the recent 2025 update incorporating the detailed guidelines for collaborative robot safety previously found in ISO/TS 15066. These standards provide guidance on:
Biomechanic Limits: ISO/TS 15066 includes data on biomechanical limits, such as maximum allowable impact forces and pressure thresholds for different body regions, to prevent human injury.
Risk Assessment: A thorough risk assessment is paramount for any cobot application. This process identifies potential hazards, evaluates their severity, and determines the necessary risk reduction measures, considering the specific tasks, end effectors, and workspace environment.
Cybersecurity: The updated ISO 10218-1:2025 also introduces cybersecurity requirements to protect collaborative applications from unauthorized access or manipulation, ensuring the integrity of safety functions.
By combining these advanced integrated features with adherence to stringent safety standards and comprehensive risk assessments, cobots can safely and effectively collaborate with humans in shared workspaces.