Speed and Separation Monitoring (SSM) is a collaborative robot safety function in which the speed of the robot is continuously regulated based on the measured distance between the robot and any human operator in the shared workspace. When the separation distance decreases below defined thresholds the robot slows or stops, and it resumes normal speed once sufficient separation is restored. SSM is standardised under ISO/TS 15066 as one of the four permitted collaborative operation modes.
Speed and Separation Monitoring (SSM) is a collaborative robot safety function that continuously adapts robot speed in inverse proportion to the measured proximity of any human operator in the shared workspace. As the operator moves closer to the robot, the robot slows; if the minimum protective separation distance is breached the robot stops. Once separation is restored to a safe threshold, the robot resumes operation automatically. SSM is one of the four collaborative operation modes defined by ISO/TS 15066 (alongside safety-rated monitored stop, hand guiding, and power/force limiting).
SSM requires at minimum a certified area-scanning sensor — typically a safety-rated LiDAR or camera system — capable of resolving the operator’s position within the robot’s protective separation distance in real time. The protective separation distance itself is calculated from the sum of the robot’s stopping distance, the operator’s approach speed, and a sensor reaction-time margin. Higher resolution sensors and faster control loops allow smaller minimum separation distances and therefore greater productivity in human-robot collaborative cells.