36 n SAFETY November/December 2025 www.drivesncontrols.com Radar safety systems: when should you use them? The general rule-of-thumb for using radar-based safety systems in automation is that they are the right choice wherever optoelectronic sensors reach their environmental limits. Compared with optoelectronic sensors, radar sensors are not only able to tolerate rugged environments contaminated with dirt and dust, but are also ideal in environments subject to extreme weather and temperature fluctuations. Conditions such as rain or intense light, as well as flying sparks or vibration, pose no problem to radar systems, which react to movements using electromagnetic waves in the two-digit gigahertz range. Radar should also be considered when it is necessary to go beyond area monitoring and to detect objects in a three-dimensional space. Radar sensors handle two safety-related functions at once: area guarding; and rear access protection. The former ensures that a machine is brought to a safe state when a danger zone is entered. Rear access protection prevents the machine from restarting unintentionally if there is still somebody in the danger zone. Scalability – such as using multiple sensors to monitor a defined zone – and a modular structure (implementing a series connection, for example) – allow safety systems to be adjusted and dimensioned precisely. Safe radar devices can also detect micromovements. In the case of rear access protection, they can detect a person's heartbeat, for example. Radar is highly sensitive to barely perceptible movements, recognising them reliably. Large-scale protection The protection zone provided by radar sensors depends on the positioning, installation height and inclination of the sensors. A safe radar system can monitor an area or zones of different sizes, depending on the type of radar selected. For example, Pilz’s PSENradar sensor has a detection range of 0-5m and, with an additional safe radar sensor, can cover a range of up to 9m. This offers advantages particularly for mobile applications in outdoor areas, especially with very large machines such as gantry cranes. In this case, a radar that can see far beyond the machine performs better than conventional radar technology. For example, if a gantry crane needs to transport material without stopping, a radar sensor can be mounted on the crane and can look beyond the crane to see if anyone is in the travel path. The detection zone of up to 9m provides an extended protection zone around the machine, even on large machinery. Complex applications are no challenge for radar systems, even in rugged environments. Typical applications are found in heavy industry, such as in mineral and steel processing, where dust, chips, welding sparks or bright light are present. Because radar technology monitors volumes, it can also be useful in woodworking, on paint lines, in cold stores or in foundries. Robot safety When safeguarding robot cells, it is essential that rear access protection and a safe restart are guaranteed. The robot application requires SIL 2 / PL d, Category 3 protection. Radar can achieve this, and brings significant advantages, not only in terms of environmental monitoring. The technology can detect all environmental conditions reliably and monitor any movements in the defined (protection) zone. However, the focus of environmental monitoring has traditionally been to monitor the standstill of a machine. Safe radar sensors are an economical alternative for robots: instead of needing to use safety light curtains for access guarding, as well as safety laser scanners for rear access protection, one radar sensor can cover both functions. Radar sensors with flexible, adaptable fields of view allow users to implement the safety of applications individually. This is particularly useful in cramped conditions, with machines located next to each other, for example. With Pilz’s system, for example, in addition to the symmetrical viewing angle, it is also possible to configure asymmetrical and corridor-like viewing angles. Users can use software to define their individual field of Radar-based safety sensors offer non-contact protection of installations and, unlike other types of safety sensor, can also monitor volumes. But when should you use this type of sensor and what potential advantages does they offer? Markus Locke, who manages sensor products at Pilz, explains. A robot in an injection-moulding application, with radar sensors visible at the bottom left and right
RkJQdWJsaXNoZXIy MjQ0NzM=