Patent Application
20220075047
The present application claims the priority of German patent application no. 10 2019 202 144.1, filed Feb. 18, 2019, which is incorporated herein by reference in its entirety.
The invention relates to factory and logistics automation. In particular, the invention relates to a radar sensor for factory and logistics automation, the use of such a radar sensor to replace an optical sensor in the field of factory and logistics automation, and the use of such a radar sensor to replace a light barrier laser sensor.
In factory and logistics automation, optical sensors are used to measure distance or angle values, for example. Other examples of applications are rotation rate sensors or sensors for detecting the presence of personnel. These optical sensors can, for example, be designed in the form of a light barrier to detect whether a person is approaching a danger zone.
It is an object of the invention to provide a cost-effective alternative to known optical sensors, and in particular to light barriers.
This object is solved by the features of the independent patent claims. Further embodiments of the invention are set forth in the dependent claims and the following description of embodiments.
A first aspect relates to a radar sensor for factory and logistics automation. The radar sensor comprises a radar circuit arrangement or circuitry with a radar chip configured to generate, emit, receive and evaluate radar measurement signals. A housing is provided in which the radar circuitry is arranged, wherein the radar chip has a cross-sectional area of less than 1 cm2 and the generated radar measurement signals have a frequency of more than 160 GHz, in particular of more than 200 GHz, and are focussed in such a way that the resulting beam aperture angle is less than 5°, or at least less than 10°, in particular even less than 3°.
For example, the radar chip has a cross-sectional area of less than 0.25 cm2.
According to one embodiment of the invention, the housing has a width of 2 cm, or less, a height of 5 cm, or less, and a depth of 5 cm, or less.
The height of the housing runs in the direction of measurement, i.e. in the direction in which the radar sensor emits its measurement signal.
For example, the housing has a screw-in thread with a diameter of at most 1.91 cm or 0.75 inch. It may also be envisaged that the housing has a screw-in thread with a diameter of at most 1.27 cm or 0.5 inch.
For example, the housing is cylindrical.
According to a further embodiment, the modulation bandwidth for the modulation of the radar measurement signals generated by the radar circuitry is above 4 GHz, in particular above 10 GHz, in particular 19.5 GHz or 31.5 GHz.
According to one embodiment, the radar sensor is configured to generate and transmit a FMCW signal (Frequency Modulated Continuous Wave Signal).
According to a further embodiment, the frequencies of the generated radar measurement signals are between 231.5 GHz and 250 GHz.
According to a further embodiment, the housing comprises a lens (or two or more lenses connected in series) which is arranged to focus the radar measurement signals emitted and/or received.
For example, the lens has a diameter of 20 mm or less.
According to a further embodiment, the radar circuitry comprises (alternatively or in addition to the housing lens) a (further) lens arranged to focus the radiated radar measurement signals before they hit the housing lens.
For example, this lens has a diameter of 10 mm or less.
For example, it is placed directly on the radiating element of the radar circuit arrangement.
According to a further embodiment, the housing lens has a distance between 5 mm to 50 mm, in particular of 30 mm or less to the radar chip and/or the further lens.
According to a further embodiment of the invention, the radar circuitry comprises a radar chip with an antenna integrated therein, onto which the lens is then placed, if provided.
According to a further embodiment, the radar sensor comprises a communication circuit, wherein the radar sensor is configured to detect changes in the physical measurement measured by the radar sensor in real time and to transmit them via the communication circuit, for example to a remote control unit.
In the context of the disclosure, “real time” means that the changes in the physical measurable variable are reliably detected and set off within a predetermined period of time. In this context, one can also speak of a soft real-time requirement. It must be ensured by the hardware and the software that no undue delays occur which could, for example, prevent compliance with the real-time condition. The processing of the data does not have to be arbitrarily fast; however, it must be guaranteed to be fast enough for the respective application.
According to another embodiment, the radar sensor comprises multiple independent transmit/receive channels and/or multiple radar chips to provide redundancy for safety-critical applications.
According to a further embodiment, the radar sensor comprises a 4 to 20 mA two-wire interface that is set up to transmit the measured values to an external process control system and to receive the energy required to operate the radar sensor.
According to a further embodiment, the radar sensor is configured as a level radar.
In particular, the radar sensor may have a plug connector, set up for ring spanner mounting of the radar sensor in an opening of a container (in which the filling material is located) provided with an internal thread.
A further aspect relates to the use of a radar sensor described above and below to replace an optical sensor in the field of factory and logistics automation, in particular in a safety-critical area such as the automated emergency shutdown of machines or systems.
Another aspect relates to the use of a radar sensor described above and below to replace a light barrier laser sensor.
Further embodiments of the invention are described below with reference to the figures. The illustrations in the figures are schematic and not to scale. If the same reference signs are used in the following description of the figures, these designate the same or similar elements.
In particular, a radar-based measuring device 102, 103 is provided, which is capable of replacing a large part of the optical sensors previously used in the field of factory and logistics automation. The measuring device can in particular be designed to provide distance or angle values. It can also be designed as a rotation rate sensor, as a sensor for presence detection or as a radar-level measuring device.
By reducing the wavelength of the radar signal through the use of higher frequencies, it is possible to simplify the design of the radar measurement device by including at least one primary radiator on the radar chip.
Whereas radar-based measurement methods could previously only be used in the field of process automation due to the size of the antenna and the size of the circuits, it will be possible in the future to provide small and powerful radar sensors for use in the field of factory automation and/or logistics automation by applying the devices proposed here.
Level measuring devices based on radar have become widespread in the field of process automation in recent years due to the many advantages of radar measurement technology. If the term automation technology is understood to mean the sub-area of technology that includes all measures for the operation of machines and systems without the involvement of humans, then the sub-area of process automation can be understood as the lowest level of automation. The aim of process automation is to automate the interaction of the components of an entire plant in the chemical, petroleum, paper, cement, shipping or mining industries.
For this purpose, a large number of sensors are known, which have been adapted in particular to the specific requirements of the process industry (mechanical stability, insensitivity to contamination, extreme temperatures, extreme pressures). The measured values of these sensors are usually transmitted to a control room, where process parameters such as filling level, flow rate, pressure or density can be monitored and settings for the entire plant can be changed manually or automatically.
For the transmission of the measured values via connections 106, 107, both wired and wireless communication standards are used, which have been optimised to meet the specific requirements of process measurement technology (robustness of signal transmission against interference, long distances, low data rates, low energy density due to explosion protection requirements).
For this reason, the measuring devices 102, 103 contain at least one communication unit to support communication standards suitable for the process industry. Examples of such communication standards are purely analogue standards such as the 4.20 mA interface or digital standards such as HART, Wireless HART or PROFIBUS.
In the control room 108, the incoming data is processed by the process control system 110 and visually displayed on a monitoring system 109. The process control system 110 or a user 111 can make changes to the settings based on the data, which can optimise the operation of the entire system 101. In the simplest case, a delivery order to an external supplier is triggered if a container 104, 105 is about to run empty.
Since the costs for the sensors 102, 103 are of secondary importance in the process industry compared to the entire system 101, higher costs can be accepted for optimal implementation of the requirements such as temperature resistance or also mechanical robustness. The sensors 102, 103 therefore have price-intensive components such as radar antennas 112 made of stainless steel. The usual price of a sensor 102, 103 suitable for process applications is therefore usually in the range of several thousand euros. The radar measuring devices 102, 103 known so far in the process industry use radar signals in the range of 6 GHz, 24 GHz or even 80 GHz for measurement, whereby the radar signals are frequency modulated according to the FMCW method in the range of the centre frequencies shown above. It is technically difficult to adapt the antennas 112 to higher modulation bandwidths desired for measurement purposes. Currently, bandwidths up to 4 GHz can be realised by using process-suitable antenna designs 112.
A completely different sub-area of automation technology concerns logistics automation. With the help of distance and angle sensors, logistics automation automates processes within a building or within an individual logistics facility. Typical applications of logistics automation systems are in the area of baggage and freight handling at airports, in the area of traffic monitoring (toll systems), in retail, parcel distribution or also in the area of building security (access control). Common to the examples listed above is that presence detection in combination with precise measurement of the size and location of an object is required by the respective application. Up to now, known radar systems have not been able to meet these requirements, which is why different sensors based on optical principles (laser, LED, cameras, ToF cameras) are used in the known state of the art.
A third sub-area of automation technology concerns factory automation. Applications for this can be found in a wide variety of industries such as automobile manufacturing, food production, the pharmaceutical industry or generally in the field of packaging. The aim of factory automation is to automate the production of goods by machines, production lines and/or robots, i.e. to let it run without the involvement of humans. The sensors used in this process and the specific requirements with regard to measuring accuracy when detecting the position and size of an object are comparable to those in the previous example of logistics automation. Therefore, sensors based on optical measuring methods are usually used on a large scale in the field of factory automation.
Another field of application for optical sensors concerns safety technology, which includes applications in the field of logistics automation as well as in the field of factory automation.
Optical sensors have dominated in the field of logistics automation as well as in the field of factory automation and safety technology. These are fast and inexpensive, and can reliably determine the position and/or distance to an object due to the relatively easy-to-focus optical radiation on which the measurement is based. A significant disadvantage of optical sensors, however, is their increased maintenance requirement, since even in the areas listed above, the sensor can become dirty after a few thousand hours of operation, which massively impairs the measurement. In addition, especially when used in production lines, the measurement can be impaired by oil vapours or other aerosols with mist formation and lead to additional contamination of optical sensors.
The aforementioned disadvantages can be overcome by using radar-based measuring devices. Before discussing the embodiments in detail,
If a known radar measuring device 102 were installed in a sorting system 201 in place of an optical sensor 206, for example, its radar signal 401 would simultaneously detect both parcels 202, 203 located on the conveyor belt 205 at a distance of several metres due to the large aperture angle 402 of typically 8° or more. The detected reflections of the packages are converted into an echo curve 403 by the radar measuring device 102 according to known procedures. If the radar-measuring device 102 operates, for example, at a frequency of 23.5 GHz to 24.5 GHz, the width dRR 404 of a single echo 405 is already 15 cm. If the distance dP 406 of the two packets 202, 203 is less than the radar resolution 404 of the measuring device 102, it can no longer be detected metrologically that two packets are involved. It should be noted that this problem arises due to the widened detection range 402 in combination with the reduced radar resolution 404. Ultimately, even ignoring the aforementioned problems, the use of the radar-measuring device 102 in the sorting system would fail at the latest because the communication device 407 of the measuring device 102 is not capable of transmitting the measured value in real time via the communication channel 410. The aforementioned disadvantages become apparent in the same way when an attempt is made to use the device in the field of safety technology (
The radar sensors described above and below provide high radar resolution and very good beam focusing in combination with a real-time capable communication device in a miniaturised design at a moderate price.
However, it is also possible to transmit the signal in the frequency converter to the target frequency range above 200 GHz by single- or multi-stage mixing. The resulting signal 605 is preferably in a range above 200 GHz, frequencies in the range between 230 GHz and 250 GHz have proved particularly advantageous. The signal is then fed to a divider 606, whereupon a portion of the radio frequency signals is radiated outwardly via a primary radiator 607 in the direction of penetration 507. With the aid of a receiving antenna 608, the radar signals reflected in the respective application are detected again, and converted into a low-frequency range in a mixer module 609. The analogue filter 610 and the analogue-to-digital converter 611 capture the signals and feed them to the processor 504 for further processing.
A key idea of the present disclosure is that increased radar resolution 404 can only be achieved by reducing the width of the echoes 405. By increasing the modulation bandwidth to more than 4 GHz, preferably more than 10 GHz or particularly advantageously to 19.5 GHz, it can be achieved that the width of the echoes can be reduced into the millimetre range. Thus, even closely spaced reflectors 202, 203, as they can occur in factory and logistics automation, can be reliably detected by measurement. In terms of circuitry, the implementation of these increased modulation bandwidths can only be mastered cost-effectively if the fundamental frequency of the radar signal is high, preferably above 200 GHz. Since the wavelength of the radar signals on a semiconductor chip then also moves into the millimetre or submillimetre range, common designs for coupler structures or the primary radiator 607 or the receiving antenna 608 can be implemented directly on the semiconductor substrate 612 of the integrated radar chip 613, which enables a low-cost design. In addition, it can be provided to bundle the radiated or received radar signals in the area of the antennas 607, 608 by beam influencing lens elements 614, 615 in order to achieve a reduced aperture angle 509 of the radar signals.
The central portion of the housing 510 has a screw-in hexagon 513 followed by a screw-in stop 514, followed by a screw-in thread 511 for screwing into a holder or the opening of a container. The screw-in thread 511 has a diameter of half an inch or less. The screw-in thread may contain, for example, a radar lens and/or the antenna for emitting/receiving the measurement signals.
Typically, the length (or “height”) of the enclosure is a maximum of 100 mm.
The embodiment of
In the embodiment according to
The large number of radar chips provides redundancy, which can be particularly advantageous for safety-critical applications.
With the embodiments described, it is possible for the first time to replace optical measurement methods in the field of factory automation, logistics automation and safety technology with radar-based measurement value acquisition, and thus to reduce the maintenance effort in particular due to the inherent insensitivity of radar measurement technology to contamination. The transition to frequencies above 200 GHz also allows the size and cost of the sensors to be significantly reduced, which means that an adequate replacement for optical sensors can be provided.
In addition, it should be noted that “comprising” and “having” do not exclude other elements or steps and the indefinite articles “a” or “an” do not exclude a plurality. It should also be noted that features or steps described with reference to any of the above embodiments may also be used in combination with other features or steps of other embodiments described above. Reference signs in the claims are not to be regarded as limitations.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2019 202 144.1 | Feb 2019 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2020/054226 | 2/18/2020 | WO | 00 |
