A camera-based monitoring system turns 3D areas around machines into virtual safety zones. Developed by Pilz Automation Safety L.P., Canton, Mich., (www.pilz.com) and DaimlerChrysler, the SafetyEYE system detects humans and objects and, when necessary, alters the movement of robots or machines to prevent accidents.

The system differs from current optoelectronic technology that might include safety fences protecting a robot workstation, and devices such as light grids, laser scanners, and area limit switches. This technology, at best, monitors only 2D planes. Worse yet, after standard devices stop a robot in the case of danger, the robot must be returned to its exact position to restart. This wastes time and slows other workstations in the production line.

In contrast, the SafetyEYE system includes a programmable control, a high-performance computer, and a sensing device with three cameras. This mounts above a workstation and views a work envelope of interest. Fiber-optic cables send camera-image data to the computer, which uses complex algorithms to generate 3D images of objects and their exact positions. The system superimposes this information over user-configured detection zones and determines whether there has been a zone violation. In turn, the computer passes results to the programmable control, which acts as the interface to the machine controller.

In this scenario, zone violations do not automatically lead to emergency stops. When the SafetyEYE detects a violation, it tells the robot to slow down. A warning signal alerts the worker, who steps back, letting the robot return to its normal speed. The robot stops immediately only when workers enter a danger zone.