Industry 4.0 (I4.0) is currently focusing in particular on the smart factory: a self-controlling factory according to the visionaries, in which the product independently tells the production systems how it should be manufactured, is at the heart of digitalization in production technology. Especially in the areas of logistics and order planning, experts see potential for increasing a company's productivity through new technologies and complete networking. All components, from the production system to the product itself, play a role in this ecosystem and form so-called cyber-physical systems (CPS), whose communication basis is Industrial Internet of Things (IIoT) technology. Technologies such as WLAN or Bluetooth LE (BLE), which have long been indispensable in the consumer sector, are also increasingly being used in the industrial environment to exchange data between CPS and the environment. Proven technologies for positioning, on the other hand, such as the Global Positioning System (GPS), do not work adequately inside buildings and are therefore ruled out as a core technology for end-to-end industrial track-and-trace applications in this area. This is precisely where ultra-wideband (UWB), a new wireless technology for industrial automation, comes in, which has established itself as the de facto standard for continuous indoor localization due to its different mode of operation.

UWB as an enabling technology for I4.0

Classic wireless communication systems use different modulation methods to transmit data, depending on the technology. Here, a high-frequency carrier signal is modified by a low-frequency wanted signal to be transmitted by the transmitter and demodulated accordingly on the receiver side in order to reconstruct the wanted signal. In contrast, ultra-wideband technology uses individual pulses for data transmission. This difference can be illustrated using the example of a pure periodic sinusoidal oscillation: If this is transferred to the image area using Fourier transformation (FT), it appears as a single spectral line. If the signal is limited to a temporal range, the width of the spectrum in the image area increases, as the spectrum of a pulse and its temporal progression are directly coupled with each other according to the rules of the FT: The shorter a pulse in the time domain, the broader the spectral representation in the image domain. Due to these very short pulses with times of 0.16 ns, a time-of-flight (ToF) measurement can be carried out between the transmitter and receiver with high resolution if the clocks are highly synchronized. The correlation between the propagation speed of the pulse and the measured time-of-flight allows the distance to be clearly determined. The advantage of ToF determination compared to alternative systems based on signal strength measurement, such as iBeacon technologies, lies primarily in the elimination of reflection interference. With a signal strength-based system, this ensures that there is no clear correlation between signal strength and distance. Due to the extremely short pulse times in the ultra-wideband system, reflections from the environment can be clearly separated and filtered from the directly radiated signal. If the system is set up in such a way that at least 4 distances from the object to be localized (generally referred to as a tag) to base stations (generally referred to as an anchor) with a known position are measured, the position of the tag can be determined by multilateration in three dimensions with an accuracy in the centimetre range. Depending on the requirements of the application, the determination rate can be configured depending on the number of tags to be localized. A constant of 352 tags per second can be determined by the system. For example, 44 tags can be localized simultaneously at 8 Hz or 88 tags at 4 Hz.