Patent Grant
10884013
The present invention relates to determining the speed and direction of a gas flow, and more specifically relates to determining the speed and direction of the gas flow based on absolute pressure measurements distributed about a surface of a cavity assembly.
The measurement of the speed and direction of a gas flow may be performed in a variety of applications. Some of these applications include measuring the speed and direction of wind, measuring the speed of air through a ventilation system, etc.
In a mechanical approach for performing such measurements, a propeller or spinning cups of a cup anemometer may spin in response to a gas flow, and the rotational speed of the propeller or spinning cups may be used to infer the flow speed. To additionally determine wind direction, a wind vane may be employed. Mechanical devices are generally lower cost than other instruments used to determine the speed and direction of a gas flow. However, mechanical devices have moving parts, and are therefore susceptible to the effects of wear and tear, leading to the degradation and eventual failure of the devices.
In an acoustical approach, an ultrasonic anemometer may be used to measure the speed and direction of a gas flow. Sonic pulses may be transmitted between pairs of transducers and the time of flight of the sonic pulses may be used to infer the speed of a gas flow. If three or more transducers are employed, the direction of a gas flow may be also determined. An ultrasonic anemometer provides the advantages of no moving parts, high accuracy, and reliability, while it has the drawbacks of higher power requirements and higher cost.
Devices other than mechanical and acoustical anemometers for measuring the speed and direction of a gas flow are described herein.
In accordance with one embodiment of the invention, a monitoring device may be used to determine the speed and direction of a gas flow. The monitoring device may comprise a cavity assembly with a plurality of cavities distributed about a flow-facing surface of the cavity assembly. Each of the cavities may have a first opening which is fluidly coupled to the gas flow. Each of the cavities may also have a second opening configured to receive a pressure sensor. The second openings may be sealed by a surface of a sensor support, on which the pressure sensors are mounted. As such, gas may flow into the cavities, but gas may not flow through the cavities, since the second openings may be sealed by the surface of the sensor support.
The pressure sensors, which may be a micro-electrical mechanical systems (MEMS) based sensor, may measure the absolute pressure of the gas within each of the cavities. Such absolute pressure measurement may be used to approximate the absolute pressure of the gas flow in the proximity of the cavity opening. At a specific time instance, a measurement may be performed by each of the pressure sensors, thereby generating a measurement of the absolute pressure of the gas flow at points distributed about the flow-facing surface of the cavity assembly.
The plurality of absolute pressure measurements may be used to determine the speed and direction of the flow of gas. In one embodiment, the logarithm of the difference between the maximum and minimum pressures may be mapped, via a pre-determined mapping, to a flow speed. In one embodiment, the plurality of absolute pressure measurements (i.e., a “pattern” of pressure measurements) may be mapped, via a lookup table, to a flow direction. In an alternative embodiment, pressure sensors may be ranked by the magnitude of their respective pressure measurements, and the ranking of pressure sensors, may be mapped, via a lookup table, to a flow direction.
These and other embodiments of the invention are more fully described in association with the drawings below.
In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments in which the invention may be practiced. It is understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention. Descriptions associated with any one of the figures may be applied to different figures containing like or similar components/steps. While the sequence diagrams each present a series of steps in a certain order, the order of some of the steps may be changed.
Cavity assembly 12 may comprise sensor-facing surface 11 and flow-facing surface 13. Sensor-facing surface 11 may be a planar surface, and may face pressure sensors 20a-20i (described below). Flow-facing surface 13 may be a three-dimensional surface which is convex and radially symmetric. The shape of flow-facing surface 13 may promote a laminar flow of the gas around cavity assembly 12. A plurality of openings 14a-14i of cavities 32a-32i may be formed on flow-facing surface 13, of which only openings 14b, 14a, 14h are visible in the exploded view. Each of the plurality of openings 14a-14i may fluidly couple cavities 32a-32i to the gas flow. In one embodiment, openings 14a-14i may have the shape of a circle, and the diameter of one of openings 14a-14i may measure 3 mm.
A plurality of pressure sensors 20a-20i may be mounted on a top surface 17 of sensor support 18, and each of sensors 20a-20i may be configured to measure an absolute pressure of the gas flow. An example of a pressure sensor is the DPS310 Digital Barometric Pressure Sensor for Mobile and Wearable Devices, available from Infineon Technologies of Neubiberg, Germany. The dimension of the DPS310 may be 2 mm×2.5 mm×1 mm. An approximation is made that the absolute pressure is substantially constant within each of cavities 32a-32i. Therefore, the absolute pressure measured by a pressure sensor (e.g., one of pressure sensors 20a-20i) deep within a cavity is used to approximate the absolute pressure of the gas flow at the opening of the cavity (e.g., one of openings 14a-14i).
As is noted above,
Sensor support 18 may be secured to base portion 22, which may comprise electronic circuitry that is configured to determine a speed and direction of the gas flow from the absolute pressure measurements. Base portion 22 is described in further detail below in
To generate the results of
For ease of understanding, the sensors that registered the maximum and minimum pressures at each of the Y-axis angle orientations of the cavity assembly are also recorded in table 63 below plot 62. It should be apparent that sensor “a” in table 63 corresponds to sensor 20a; sensor “i” in table 63 corresponds to sensor 20i, and so on. At a 0° rotation of the cavity assembly about the Y-axis, sensor 20a registered the maximum pressure, which is expected as the gas flow exerts the maximum force on cavity 32a. At a 90° rotation of the cavity about the Y-axis, opening 14i faces the gas flow. Sensor 20i registers the maximum pressure, which is expected as the gas flow exerts the maximum force on cavity 32i.
One important observation from plot 62 is that log (Pmax−Pmin) for each flow speed is nearly constant over the various orientations of the cavity assembly about the Y-axis. Therefore, an approximation may be made that log (Pmax−Pmin) for each flow speed is independent of the orientation of the cavity assembly about the Y-axis.
For flow speeds less than 2 m/s, log (Pmax−Pmin) was not constant over the various orientations of the cavity assembly about the Y-axis (these results not depicted). The variation in log (Pmax−Pmin) was likely not due to the varying orientations of the cavity assembly, but rather due to the rounding errors caused by the 1 Pascal accuracy of the measurements. For flow speeds less than 2 m/s, the simulations indicate that pressure sensors with a degree of accuracy less than 1 Pascal are needed.
To generate the results of
The absolute pressure at each of pressure sensors 20a-20i was calculated with a 1 Pascal degree of accuracy (i.e., absolute pressure calculations were rounded to the nearest 1 Pascal).
For ease of understanding, the sensors that registered the maximum and minimum pressures at each of the Z-axis angle orientations of the cavity assembly are also recorded in table 65 below plot 62. At a 0° rotation of the cavity assembly about the Z-axis, sensor 20a registered the maximum pressure, which is expected as the gas flow exerts the maximum force on cavity 32a. At a 45° rotation of the cavity assembly about the Z-axis, opening 14b faces the gas flow. Sensor 20b registers the maximum pressure, which is expected as the gas flow exerts the maximum force on cavity 32b.
One important observation from plot 64 is that log (Pmax−Pmin) for each flow speed is nearly constant over the various orientations of the cavity assembly about the Z-axis. Therefore, an approximation may be made that log (Pmax−Pmin) for each flow speed is independent of the orientation of the cavity assembly about the Z-axis.
For flow speeds less than 2 m/s, log (Pmax−Pmin) was not constant over the various orientations of the cavity assembly about the Z-axis (these results not depicted). Again, the variation was likely not due to the varying orientations of the cavity assembly, but rather due to the rounding errors caused by the 1 Pascal accuracy of the measurements. For flow speeds less than 2 m/s, the simulations once again indicate that pressure sensors with a degree of accuracy less than 1 Pascal are needed.
In plots 62 and 64, log (Pmax−Pmin) is nearly constant for each of the flow speeds not only within the plots, but also nearly constant across the plots. Therefore, the simulations reveal that the log (Pmax−Pmin) is substantially independent of the orientation of the cavity assembly (whether the rotation is about the X-, Y- or Z-axes). As a result, a mapping between (i) log (Pmax−Pmin) and (ii) the flow speed (independent of the orientation of the cavity assembly) may be formed, and such a mapping is depicted in
In
It should now be apparent how the flow speed may be determined from the absolute pressure measurements. First, a mapping similar to the mapping depicted in plot 66 may be generated for a cavity assembly. Such mapping may be generated using computational fluid dynamic simulations (as discussed above) or using actual measurements. In the case of using actual measurements, plots 62 and 64 may first be generated using actual measurements (e.g., by placing a monitoring device at a particular orientation in a gas flow calibrated at a particular velocity, measuring absolute pressure using the pressure sensors of the monitoring device, calculating log (Pmax−Pmin)). The property of the log (Pmax−Pmin) being independent of the Y- and Z-axis orientation may be confirmed. Finally, a mapping from log (Pmax−Pmin) may be generated from plots 62 and 64, as discussed above. After the mapping from log (Pmax−Pmin) to flow speed has been generated, such mapping may be used to map a measured log (Pmax−Pmin) reading to a flow speed. If not already apparent, Pmax and Pmin are not constrained to be measured by any two particular ones of the pressure sensors. For instance, in a first measurement at time 1, Pmax and Pmin may be measured by sensors 20a and 20d, respectively, but in a second measurement at time 2 (e.g., following the change in the direction and/or speed of the gas flow), Pmax and Pmin may be measured by sensors 20a and 20f, respectively.
Lookup table 68 was generated using computational fluid dynamic simulations, but also could be generated using actual measurements or machine learning techniques. In the case of fluid dynamic simulations, pressure measurements for pressure sensors 20a-20i may be calculated for a gas flow which flows past a monitoring device at a particular orientation. In the upper right portion of
In the case of actual measurements, pressure measurements for pressure sensors 20a-20i may be measured for a gas flow which flows past a monitoring device at a particular orientation. The pressure sensors 20a-20i may be ranked according to the magnitude of their respective pressure measurements, and the pairing of a vector of rankings and the gas flow direction may likewise be stored in lookup table 68. Such process may be repeated for numerous gas flow directions to populate table 68.
As there are many more possible rankings than possible flow direction (assuming 5° granularity in flow directions), it is not unlikely that there will be a vector of rankings that is not mapped to a flow direction in table 68. In such case, machine learning may be used to infer an appropriate flow direction for a particular vector of rankings. The training of a model, and the application of the model in a machine learning algorithm is described below in
It is noted that the flow direction determination was described above with respect to a flow direction in the X-Y plane (i.e., an azimuth angle or an angular orientation of the gas flow with respect to the Z-axis). In other embodiments, similar techniques could be applied to further determine the flow direction with respect to the Y-Z plane (i.e., angular orientation of the gas flow with respect to the X-axis), and the flow direction with respect to the X-Z plane (i.e., angular orientation of the gas flow with respect to the Y-axis). For instance, a table (similar to table 68) may be generated and used to map a pressure pattern to a Y-axis angle, and a further table (similar to table 68) may be generated and used to map a pressure pattern to an X-axis angle.
In a further embodiment (not depicted), the principles of the present invention may be applied to large-scale applications (e.g., agricultural, architectural, or industrial applications). A network of the monitoring devices can be distributed to characterize the environment over a region (e.g., a field or a factory). The devices can be networked (e.g., via a mesh network) to propagate data to a central network node to be gathered for analysis. Such analysis could improve processes that are influenced by the movement of air (e.g., fighting of a forest fire, installation and maintenance of wind turbines, etc.).
In a further embodiment, it is contemplated that the speed information determined by a monitoring device may be supplied to a controller (not depicted), which may aggregate several inputs of movement/position/velocity (e.g., measured via accelerometer, gyroscope, etc.) and utilize sensor fusion to compute a more precise determination of the speed and/or position of a person or device.
In the application of flow direction model 150, a vector of pressure measurements may be provided as input to flow direction model 150, and flow direction model 150 returns a flow direction. In the example provided in
System 200 includes a bus 202 or other communication mechanism for communicating information, and a processor 204 coupled with the bus 1002 for processing information. Computer system 200 also includes a main memory 206, such as a random access memory (RAM) or other dynamic storage device, coupled to the bus 202 for storing information and instructions to be executed by processor 204. Main memory 206 also may be used for storing temporary variables or other intermediate information during execution of instructions to be executed by processor 204. Computer system 200 further includes a read only memory (ROM) 208 or other static storage device coupled to the bus 202 for storing static information and instructions for the processor 204. A storage device 210, for example a hard disk, flash memory-based storage medium, or other storage medium from which processor 204 can read, is provided and coupled to the bus 202 for storing information and instructions (e.g., operating systems, applications programs and the like).
Computer system 200 may be coupled via the bus 202 to a display 212, such as a flat panel display, for displaying information to a computer user. An input device 214, such as a keyboard including alphanumeric and other keys, may be coupled to the bus 202 for communicating information and command selections to the processor 204. Another type of user input device is cursor control device 216, such as a mouse, a trackpad, or similar input device for communicating direction information and command selections to processor 204 and for controlling cursor movement on the display 212. Other user interface devices, such as microphones, speakers, etc. are not shown in detail but may be involved with the receipt of user input and/or presentation of output.
The processes referred to herein may be implemented by processor 204 executing appropriate sequences of computer-readable instructions contained in main memory 206. Such instructions may be read into main memory 206 from another computer-readable medium, such as storage device 210, and execution of the sequences of instructions contained in the main memory 206 causes the processor 204 to perform the associated actions. In alternative embodiments, hard-wired circuitry or firmware-controlled processing units may be used in place of or in combination with processor 204 and its associated computer software instructions to implement the invention. The computer-readable instructions may be rendered in any computer language.
In general, all of the above process descriptions are meant to encompass any series of logical steps performed in a sequence to accomplish a given purpose, which is the hallmark of any computer-executable application. Unless specifically stated otherwise, it should be appreciated that throughout the description of the present invention, use of terms such as “processing”, “computing”, “calculating”, “determining”, “displaying”, “receiving”, “transmitting” or the like, refer to the action and processes of an appropriately programmed computer system, such as computer system 200 or similar electronic computing device, that manipulates and transforms data represented as physical (electronic) quantities within its registers and memories into other data similarly represented as physical quantities within its memories or registers or other such information storage, transmission or display devices.
Computer system 200 also includes a communication interface 218 coupled to the bus 202. Communication interface 218 may provide a two-way data communication channel with a computer network, which provides connectivity to and among the various computer systems discussed above. For example, communication interface 1018 may be a local area network (LAN) card to provide a data communication connection to a compatible LAN, which itself is communicatively coupled to the Internet through one or more Internet service provider networks. The precise details of such communication paths are not critical to the present invention. What is important is that computer system 200 can send and receive messages and data through the communication interface 218 and in that way communicate with hosts accessible via the Internet. It is noted that the components of system 200 may be located in a single device or located in a plurality of physically and/or geographically distributed devices.
Thus, methods and systems for measuring the speed and direction of a gas flow have been described. It is to be understood that the above-description is intended to be illustrative, and not restrictive. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.
This application is a Continuation Application of U.S. application Ser. No. 16/415,115, filed on 17 May 2019 (now issued as U.S. Pat. No. 10,598,683), which is a Continuation Application of U.S. application Ser. No. 15/397,426, filed on 3 Jan. 2017 (now issued as U.S. Pat. No. 10,324,104), which is a non-provisional patent application of and claims priority to U.S. Provisional Application No. 62/274,447, filed 4 Jan. 2016, each of which is incorporated by reference herein.
| Number | Name | Date | Kind |
|---|---|---|---|
| 4393451 | Barker | Jul 1983 | A |
| 4453419 | Engelke | Jun 1984 | A |
| 5231596 | Nakazawa et al. | Jul 1993 | A |
| 5297421 | Hosonuma et al. | Mar 1994 | A |
| 5423209 | Nakaya et al. | Jun 1995 | A |
| 5485843 | Greenstein et al. | Jan 1996 | A |
| 5832411 | Schatzmann et al. | Nov 1998 | A |
| 5929331 | Kinser | Jul 1999 | A |
| 6237426 | Gryc et al. | May 2001 | B1 |
| 6601460 | Materna | Aug 2003 | B1 |
| 7093483 | Corey et al. | Aug 2006 | B2 |
| 8687175 | Diatzikis et al. | Apr 2014 | B2 |
| 9279666 | Balasubramaniam | Mar 2016 | B1 |
| 9476900 | Akada | Oct 2016 | B2 |
| 20020100316 | James | Aug 2002 | A1 |
| 20060060001 | Kurtz | Mar 2006 | A1 |
| 20070256506 | Sette | Nov 2007 | A1 |
| 20090071258 | Kouda | Mar 2009 | A1 |
| 20100006670 | Bourrilhon | Jan 2010 | A1 |
| 20110094311 | Khimji | Apr 2011 | A1 |
| 20120224955 | Vine | Sep 2012 | A1 |
| 20130270446 | Dardona | Oct 2013 | A1 |
| 20140123751 | Lu | May 2014 | A1 |
| 20140124057 | Freund | May 2014 | A1 |
| 20140130608 | Adams | May 2014 | A1 |
| 20140152468 | Obenchain | Jun 2014 | A1 |
| 20150017619 | Ashmore | Jan 2015 | A1 |
| 20150320950 | Borner | Nov 2015 | A1 |
| 20150364315 | Ramsey | Dec 2015 | A1 |
| 20150377662 | Ray | Dec 2015 | A1 |
| 20160131013 | Yi | May 2016 | A1 |
| 20160377469 | Teli | Dec 2016 | A1 |
| 20170192031 | Ashmore | Jul 2017 | A1 |
| 20170197056 | Van Schalkwyk et al. | Jul 2017 | A1 |
| Number | Date | Country |
|---|---|---|
| 2016135061 | Sep 2016 | WO |
| Entry |
|---|
| International Search Report and Written Opinion dated Mar. 23, 2018, from the ISA/US, for International Patent Application No. PCT/US18/12109 (filed Jan. 2, 2018), 11 pages. |
| Notice of Allowance dated Feb. 6, 2019, for U.S. Appl. No. 15/397,426, filed Jan. 3, 2017, 8 pages. |
| Amendment filed Jan. 10, 2019, for U.S. Appl. No. 15/397,426, filed Jan. 3, 2017, 9 pages. |
| Non-Final Office Action dated Dec. 20, 2018, for U.S. Appl. No. 15/397,426, filed Jan. 3, 2017, 11 pages. |
| Supplemental Amendment filed Oct. 3, 2018, for U.S. Appl. No. 15/397,426, filed Jan. 3, 2017, 3 pages. |
| Amendment filed Sep. 19, 2018, for U.S. Appl. No. 15/397,426, filed Jan. 3, 2017, 6 pages. |
| Non-Final Office Action dated Sep. 6, 2018, for U.S. Appl. No. 15/397,426, filed Jan. 3, 2017, 11 pages. |
| International Preliminary Examination Report on Patentability dated Jul. 18, 2019, from the International Bureau of WIPO, for International Application No. PCT/US2018/012109 (filed Jan. 2, 2018), 10 pages. |
| Notice of Allowance dated Nov. 12, 2019, for U.S. Appl. No. 16/415,115, filed May 17, 2019, 9 pages. |
| Amendment filed Oct. 22, 2019, for U.S. Appl. No. 16/415,115, filed May 17, 2019, 10 pages. |
| Non-Final Office Action dated Jul. 31, 2019, for U.S. Appl. No. 16/415,115, filed May 17, 2019, 15 pages. |
| Number | Date | Country | |
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| 20200200790 A1 | Jun 2020 | US |
| Number | Date | Country | |
|---|---|---|---|
| 62274447 | Jan 2016 | US |
| Number | Date | Country | |
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| Parent | 16415115 | May 2019 | US |
| Child | 16805359 | US | |
| Parent | 15397426 | Jan 2017 | US |
| Child | 16415115 | US |
