With the LBK safety radar system, Leuze has added an innovative sensor system to its product range, implementing an operating principle novel to safety technology. As a result, it is also able to provide a solution for applications that previously could not be solved reliably using optical sensors, even in harsh environments where e.g. sparks, dirt and dust occur. The manufacturer of the 3D safety system is the Italy-based Inxpect. The LBK safeguards danger zones close to machinery and systems.
The LBK system operates in a frequency range of 24 GHz. This means that the electromagnetic waves are much shorter than sound waves. Unlike light, the radar waves can penetrate non metallic objects. The compact sensors with their integrated antennas emit electromagnetic waves. These waves are reflected off objects. The sensors receive these reflections and then evaluate them. The electromagnetic waves of the LBK radar system are completely harmless to personnel.
The LBK system is particularly suitable for applications in harsh environments, for example in wood or plastic processing. Such applications typically produce a large quantity of particles that are then suspended in the air. However, these particles do not prevent the LBK from performing its task of reliably detecting and protecting persons. Even if radar waves penetrate the particles, the latter still reflect a small proportion of the waves. As the quantity of radar waves reflected by a person is significantly different to that reflected by wood chips or moisture, the LBK can detect whether the reflection comes from a person or from non metallic particles.
The LBK sensor emits its radar waves in three dimensional space so that not only the surface area but also the volume of this space is monitored. This allows the LBK to detect persons who enter a hazardous area or who are located in this area, regardless of whether they are standing, kneeling or lying. The LBK 3D radar system uses FMCW, Frequency-Modulated Continuous Wave. Here, the transmission frequency changes within a defined bandwidth. Starting at a fundamental frequency, it increases continuously up to a maximum frequency and then returns to the fundamental frequency again. If a person reflects this signal, it reaches the receiver with a time delay. Subtraction of the reception signal from the transmission signal produces a difference frequency.
If the distance between the LBK sensor and the person remains constant, the difference frequency also retains its value. However, if the person moves, the time delay between the transmitted and received signal changes, and therefore also the difference frequency. The faster the person moves, the greater the change in difference frequency will be. In this way, the LBK sensor is able to determine the speed at which the person is moving.
In addition to use in harsh environments, the LBK safety radar system is used for preventing unwanted restarts and for monitoring hidden areas. Users can adapt it to their individual requirements. The system consists of a controller to which up to 6 radar sensors can be connected. The positioning of the sensors, the adjustable operating range and the selectable opening angle allow flexible adaptation of the monitored area to the danger zone, allowing areas on steps or pedestals to be monitored reliably. The user can define the system parameters using the easy to operate configuration software.