“Radar is superior in many harsh applications.”

Radar sensors pick up where ultrasonic sensors fail due to strong wind, dust, or rain – especially in mobile applications such as smart farming, road construction, AGVs, high-bay warehouses, or port cranes. Laser sensors also often have problems, for example in offshore installations or desert areas. "With radar technology, we have a real physical alternative available for all these applications," reports Raphael Penning, product manager at TURCK GmbH. The technology has long been in use on ships and at airports and has proven itself – albeit with rather large antennas. "Thanks to modern semiconductor technology, these have now shrunk to a few centimeters, and due to their use in cars, the technology has also become affordable."

FMCW measurement principle provides technical basis

All three types of radar sensors presented here physically use the FMCW (Frequency Modulated Continuous Wave) principle. Here, the sensor continuously emits a frequency-modulated signal and analyzes the backscattered signals using frequency analysis. "This not only enables interference from objects such as drop grids or shackles in the measuring range to be suppressed, but also allows relevant process data to be reliably separated," emphasizes Penning. A key feature of the sensors at this point is the integration of IO-Link as a communication interface. "We communicate mainly via IO-Link because it simply allows us to extract more data from the process. Our IIoT ecosystem – the TURCK Automation Suite (TAS) – enables the visualization and analysis of radar data and supports rapid commissioning together with the user." Parameterization is easily done via drop-down fields.

Radar sensors at a glance

TURCK currently offers a range of modern radar sensors – for distance control (DR), 3D object detection (MR), and level measurement (LRS series), for example. The various radar sensors are designed for different applications.

Distance Radar (DR) – smart sensors for harsh environments

Radar sensors in the DR series are suitable for distance measurement up to 30 m – even under harsh conditions such as outdoor use of mobile machines in smart farming, road construction, or port logistics. One advantage is that the lens design can cover a wide range of applications – from pure distance measurement with a focused lens to collision avoidance with a wide radar front. This enables pinpoint detection over long distances, for example for distance control, as well as wide-area monitoring, for example for collision avoidance. 

"For example, we offer a variant that focuses on 2.5 degrees and can see 30 meters ahead – or an elliptical lens that can illuminate 45 degrees," explains Raphael Penning. In addition, retro-reflectors, known as corner cubes, are available to improve signal quality in demanding applications. "With both variants, we can measure very accurately – in a static environment over 15 meters, for example, the distance can be measured to within one millimeter." The systems operate at 122 GHz (millimeter waves), with 100 mW of transmission power already sufficient. In addition, the devices are housed in stainless steel enclosures with IP67/69K protection and are shock-resistant up to 100 g.

Multi-Radar (MR) – 3D object detection

The multi-radar scanner marks the leap into 3D object detection. Using an antenna array, objects are no longer only detected in a line, but also in their position. "The huge advantage over LiDAR is that no moving parts are used," emphasizes the product manager. Because there are no moving mirrors, the purely electronic radar scanner, which operates at 60 to 64 GHz, also offers 100 g shock resistance.

The radar sensor is used, for example, in convoy driving of mobile machines – whether in agricultural harvesting or road construction. "Compared to the laser sensors used in the past, these applications benefit from the insensitivity of radar technology to dust – which means that the respective work process can continue uninterrupted and is not interrupted by sensor malfunctions," Penning continues.

Level Radar Sensor (LRS) – Level measurement at the limit

In addition, the LRS series is particularly suitable for classic level measurement applications – especially where floats or capacitive measuring rods fail due to the viscosity of the medium, contamination, or lack of hygiene suitability. Radar scores here with media-free measurement, robustness, and precision. Ranges of up to 10 m enable applications in small tanks, such as those commonly used for monitoring ketchup storage tanks or oil tanks in food processing. These applications also benefit from the suppression of interfering objects via signal processing – such as drop grids mounted above the tank. A normal ultrasonic sensor would detect the grid and not provide correct values.

Limitations and future prospects 

However, radar sensors must also be used within the limits of physics. For example, thin wires or very small organic targets cannot be reliably detected by radar. "We therefore provide support during commissioning – because together with our customers, we can look at the visualization of the raw data and parameterize the system accordingly," says Raphael Penning. "The key is to know exactly what needs to be detected."
TURCK is also actively addressing the issue of functional safety. "The complexity of the applications places high demands on technical implementation, but we will also be able to offer solutions here," concludes the product manager.