COBOTS SAFETY GUIDE
How these unique collaborative robot safely manage operational risks
Unlike typical industrial robots that operate behind safeguarding, Baxter® and Sawyer™, the collaborative robots from Rethink Robotics, are designed to work effectively directly alongside people in a factory setting, making it possible to deploy in environments which have historically been off-limits to robotic automation. Rethink’s Collaborative Robots combine a number of unique technologies designed to allow deployment without some of the traditional safeguarding described in ANSI, ISO, or other safety standards, based on the application’s risk assessment. Baxter and Sawyer are designed for:
- Physical interaction between a worker and the robot.
- Avoiding accidental contact.
- Minimizing forces and stopping on human contact.
Rethink’s Collaborative Robots meet the requirements of a collaborative robot that is Power and Force Limited by Inherent Design as described in ISO 10218-1: 2011, section 5.10.5. The most recent edition of ISO 10218-1 does not include these power and force limiting collaborative requirements, but instead points to the requirement in ISO 10218-2 requiring a risk assessment of the entire robotic application, and refers readers to Technical Specification ISO TS 15066:2016 for further guidance. ISO 10218-1 & -2 are the de facto international robot safety standards and have been adopted around the globe, for example, ANSI RIA R15.06-2012 is a U.S.-national adoption of ISO 10218-1 & 2.
Rethink’s Collaborative Robot Safety Features
1. Safety by Design: Baxter and Sawyer operate at human-equivalent speeds which are limited by their inherent design. This makes it easier for integrators to assess the risks associated with robot motion, and allows nearby operators to avoid any unintended contact with the robot. Series Elastic Actuators (SEAs) not only sense contact, but also physically flex on contact, absorbing energy.
2. Machine Safety: Rethink’s Collaborative Robots are designed with many protective features which govern operation and protect those working around them, including the emergency stop function, both electrical and physical braking systems, and manual brake releases for manipulating the arm even without power.
3. Contact Detection: Baxter and Sawyer have Series Elastic Actuators that directly measure torque at every joint, monitoring for sudden impacts, soft obstructions, or excess forces or torques and stopping the robot.
4. Diverse Internal Checking Subsystems: Various subsystems disable motor power and enable joint brakes if a control error or failure is detected.
5. Sensing and Behavior: Baxter and Sawyer use their lights during operation to signal status, and their eyes to signal intent by looking in the direction of the next motion.