Pilz Automation Safety L.P. is opening new horizons for factory and nonfactory automation with SafetyEYE, a camera system for three-dimensional safety monitoring. Developed by Pilz in conjunction with DaimlerChrysler, SafetyEYE places a customized, three-dimensional protective cocoon around a danger zone with a single system, which has the potential to replace a multitude of two-dimensional sensors currently in use today. It protects, controls and monitors, and detection zones can be configured flexibly and quickly on a PC.
"Camera-based image processing will revolutionize optical sensor technology, and not only in the industrial sector," says Pilz Managing Partner Renate Pilz. "We are convinced that the SafetyEYE innovation faces an excellent future in the security sector, too." Much more than just a sensor, SafetyEYE is the basis for a technology that safely detects objects in a three-dimensional zone and alters a robot or a machine's movement to prevent accidents. It is suitable for the widest range of industries and applications: from manufacturing operations to the tire and packaging industries, to high-bay racking systems and automatic car parks. In addition to the safety and security benefits of three-dimensional production monitor and control, SafetyEYE also can lead to increased flexibility and productivity from uninterrupted object monitoring and access guarding.
Current safety-related solutions have their limits
Looking at an example of a robot workstation comprising one or more robots and protected by safety fences, the robots generally require additional protective devices such as light grids and laser scanners in conjunction with an area limit switch. If someone enters or remains in the danger zone, these devices will detect it. Current safety-related solutions, however, have significant disadvantages.
Optoelectronic protective devices are unable to monitor three-dimensional zones. At best they monitor two-dimensional planes. If there is no visual contact, then the workstation must also be protected using pressure-sensitive mats. Uninterrupted monitoring of a robot's operating range is only possible with a great deal of technical investment, if at all. Another factor is that standard protective devices immediately stop the robot in the case of danger. The robot must be returned to its exact position prior to the stop in order to restart. This costs time and impacts subsequent workstations in the production line. A third aspect is the large number of different components and the complex wiring they involve. It's not only expensive to safeguard a robot workstation, but also can have a negative impact on its availability.
Joint expertise for an innovative solution
In an effort to lessen the expense and improve productivity, Pilz started to develop a new concept for zone monitoring and the safe camera system. In Sindelfingen, Germany, DaimlerChrysler's process development, automation and control technology department also was considering some new monitoring strategies. The automaker had an idea to use a combination of cameras and image-processing algorithms to enable the monitored detection zone to be reproduced in 3D and detect objects that encroached into the danger zone.
Developed at the technical image-processing laboratory at DaimlerChrysler's research center in Ulm, Germany, the same visual-assistance systems used in cars to make drivers aware of hazards, were used as the starting point. This ideal cooperative effort had DaimlerChrysler contributing the appropriate algorithms for three-dimensional image evaluation, Pilz making the algorithms suitable for industrial use, and then developing and manufacturing the system.
One system to control, monitor and protect
The overall system is made up of three components: the sensing device, a high performance computer and a programmable safety and control system. The sensing device consists of three highly dynamic cameras that provide the image data from the zone being monitored.
The high performance computer operates as the analysis unit, receiving the camera's image data via fiber-optic cables and works out a three dimensional image using highly complex and safe algorithms. This way it is possible to observe objects three-dimensionally and to define their exact position. This information is then superimposed over the detection zones configured within the system to determine whether there has been a zone violation.
The high performance computer passes the image processing results to the PSS programmable safety and control system. With its inputs and outputs, the PSS is the interface to the machine controller and controls the whole SafetyEYE operation. If the analysis unit signals that the detection zone has been violated, the configurable outputs are shut down. Connection to the periphery also can be via the SafetyBUS p safe bus system. In future, this also will be possible via the SafetyNET p Ethernet. The detection zones and warning zones, as well as all the other parameters required to operate the safe camera system, can be set up using the configuration PC and a special software package.
Perfectly compatible safety concepts help to prevent downtime
A robot workstation that is safeguarded using SafetyEYE, for example, will be fully open in its operation. Restrictive barriers are no longer necessary. The sensing device sits above the workstation and has a complete overview of the robot's operating range. So the possibility of manipulation is excluded from the outset. One glance at the monitor shows that safety technology is at work. Color, semi-transparent cubes and cuboids – the three dimensional warning and detection zones – are superimposed onto the images from the cameras (see graphic illustrating the functional setup). The robot moves within these zone segments during its work cycle. The danger zones are defined in the form of a virtual envelope, which incorporates the warning zones and detection zones. Only objects that enter these zones are potentially at risk.
The special feature of SafetyEYE is that a detection zone violation does not automatically lead to an emergency stop. Should a worker infringe the virtual detection zone at a point that the robot would still take several seconds to reach, the control technology ensures that the robot advances at extremely reduced speed. If the worker is alerted through a warning signal and steps back, the robot will return to normal speed. There will only be an emergency stop if the worker enters the immediate danger zone. This is a clear advantage over conventional protective devices, which trigger an immediate standstill in the case of danger. With SafetyEYE processes can be precision controlled and can have flexible safeguards.
Configure warning and protection zones on the PC
Detection zones and warning zones can be combined into complex zone arrangements and are therefore easy to manage, as they can be configured quickly and intuitively on the PC. If the various operating modes on a machine require different zone arrangements, these can be switched dynamically during the machine's working cycle, via the safe bus system SafetyBUS p or via the digital inputs on the PSS programmable safety and control system. Users have flexibility because once detection zones have been defined they can be adapted at the click of a mouse in the SafetyEYE Configurator. The monitoring of detection zones is no longer based on technical needs but on the requirements of the
user's process cycles, which can be designed with the utmost flexibility.
It only takes a few hours to install SafetyEYE and configure the detection zones. To position, set up
and check conventional protective devices, on the other hand, takes at least a day. It is also more economical to use SafetyEYE. When a detection zone has been violated, an integrated diagnostic function reduces downtimes to a minimum. "So once more we can present an innovation that helps users to increase productivity and reduce costs," says Renate Pilz, Pilz's Managing Partner, getting right to the heart of the benefits of the safe camera system.
Ergonomic interaction between worker and machine
SafetyEYE also can perform standard control functions as well as monitor several independent detection zones. Not only does that lower the cost, it also reduces the number of components to a minimum. The ability to connect directly to bus systems such as SafetyBUS p and, in future SafetyNET p, brings further savings in terms of material and installation.
SafetyEYE protects plants from a bird's eye view, enabling man and machine to work together harmoniously. Requirements from the widest range of mechanical engineering applications can be implemented using the safe camera system.
Valuable objects and access to buildings firmly in view
While safety describes the protection of the environment from an object, security is concerned with protecting an object from the environment. This includes building access protection or monitoring exhibits at museums. SafetyEYE keeps valuable objects continuously in its sight because, unlike conventional protective devices, is doesn't just monitor one plane.
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