Method and apparatus to non-intrusively measure the weight of loose bulk material within a rigid containing structure

A method and system can measure the weight of a bulk material within a container by applying excitation in the form of vibrational energy and interpreting the container's response to the vibration.

Not Applicable.

REFERENCE TO A MICROFICHE APPENDIX

Not Applicable.

RESERVATION OF RIGHTS

BACKGROUND OF THE INVENTION

I. Field of the Invention

The present invention relates to improvements in measuring the amount of a bulk material within a container in a non-intrusive manner. In particular, the present invention relates to applying excitation in the form of vibrational energy and interpreting the container's response to the vibration to determine the amount of bulk material.

2. Description of the Known Art

As will be appreciated by those skilled in the art, vibrational sensors are known in various forms. Patents disclosing information relevant to vibration al sensing include:

U.S. Pat. No. 8,571,829, issued to Atlas, et al. on Oct. 29, 2013 entitled Detecting objects in shipping containers by vibration spectral analysis. The abstract states: Objects in a cargo shipping container are detected by measuring vibration resonant frequency peaks of the container. The mass of an object on the floor of the container effects the vibration resonance of the container, enabling the object to be detected. A vibration source and a plurality of accelerometers are either attached to the steel structure of the container, or are disposed on a supporting structure, such as a cargo crane or lift, so that they contact the container. The vibration source causes the container to vibrate, and the accelerometers detect the vibration resonance of the container. A mismatch between a cargo manifest and an observed cargo, or detection of an object having relatively high mass, e.g., due to lead shielding, can justify a manual inspection. The process uses synchronous processing to achieve the sensitivity needed, is unobtrusive, and does not slow the flow of cargo through a facility.

United States Patent Application No. 20140157889A1, filed by Eakin; George R., published on Jun. 12, 2014 entitled SYSTEM FOR MEASURING LEVEL OF DRY BULK MATERIAL IN CONTAINER. The abstract reads: A system for measuring a level of dry bulk material within a container has a columnar device supported vertically within the container. The columnar device has a closed lower end and openings through a sidewall thereof for allowing dry bulk material within the container to flow into and out of the columnar device. A load cell is used to measure a weight of the dry bulk material within the columnar device, which is then correlated to the level of dry bulk solids within the container. The columnar device and the sidewall openings therein can be provided in various shapes and configurations.

European patent publication number EP0119790 A1, invented by Peter Atkinson, filed on Mar. 8, 1984 entitled Liquid level monitoring. The abstract reads: The level of liquid in a container, for example an upright cylinder of the kind used to store liquefied gas, is monitored by measuring the resonant frequency of the container and comparing it with a pre-determined standard. The resonant frequency is measured by applying mechanical vibrations, preferably of a frequency up to 1 OkHz, to the container and monitoring the resonant frequency using known methods. The results obtained are compared with the pre-determined standard, which is for example a calibration graph, to determine accurately the degree of filling of the container.

German patent publication number DE10136754 A1, invented by Mario Bechtold, and Markus Vester, field on Jul. 27, 2001, entitled Verfahren and Vorrichtung zur Dichtebestimmung. The machine translation of the title is Density measurement for medium in container, comprises feeding questioning signal into probe and then detecting response signal. The machine translation of the abstract reads: Determining the density of a medium (30) in a container (20) comprises using a probe (10). A questioning signal (S1) is fed into the probe and a response signal (S2) is detected. A medium reflection factor or impedance is determined along the probe, based on the response time, and the density along the probe is determined using these values. The questioning signal band width is at least 50 MHz, especially 100 MHz.

Each of these patents and publications are hereby expressly incorporated by reference in their entirety.

From these prior references it may be seen that these prior art patents are very limited in their teaching and utilization, and an improved sensor method and apparatus is needed to overcome these limitations.

SUMMARY OF THE INVENTION

The present invention is directed to an improved vibrating energy phase shift measuring apparatus using a vibration source and a vibration sensor. The invention described herein is used to determine the level of feed content in a feeder silos used in commercial farming. Feed weight in the silo is determined by measuring and analyzing vibration profiles of the container when a known excitation is applied. A vibration source and at least one vibration sensor are placed on the structure. The vibration source is used to apply a predetermined vibration signal to the silo. The vibration source applies a variable vibration frequency that sweeps through the natural resonant frequency of the silo. The energy transferred from the vibration source to the vibration sensors is inversely proportional to the weight of the feed in the silo. The weight of the feed dampens the vibration so less energy reaches the sensor. Programming the vibration source to sweep through the resonant frequency of the silo induces the greatest possible vibration amplitude, and allows for the dampening effect of increased feed weight to be measured by calculating the quality factor (Q) of the oscillation of the silo.

For a given size of container, the vibration response will be calibrated. The calibration procedure involves starting with an empty silo and transferring known quantities of feed to the silo and taking vibration measurements at each step. This calibration procedure does not need to be completed for individual silos, only once for a given type of silo.

Overall, the system comprises a power source or power interface, at least one microcontroller, at least one accelerometer, at least one vibration excitation device, a transmitter, and a mechanical coupling mechanism. The system is packaged utilizing known methods for weather proofing. The packaging attaches to the silo through magnetic or mechanical fasteners. The steps for the method include:1) Provide mechanical excitation to a rigid feed container.2) Use a vibration sensor to measure the vibration response.3) Calculate the frequency spectrum of the vibration response.4) Determine the energy in the signal from the time or frequency domain.5) Determine the volume of bulk material based on the frequency spectrum, signal amplitude, and previously obtained calibration data.6) Transmit the calculated information to a receiver.
In this manner, remote sensing of feed quantities can be communicated to a feed supply manager to ensure timely delivery of feed and allow remote management of feed supplies. These and other objects and advantages of the present invention, along with features of novelty appurtenant thereto, will appear or become apparent by reviewing the following detailed description of the invention.

DETAILED DESCRIPTION OF THE INVENTION

As shown inFIGS.1through5of the drawings, one exemplary embodiment of the present invention is generally shown as a vibrating energy phase shift measuring apparatus100. The embodiment described herein is being placed on a galvanized metal silo10. The silo10includes a silo roof12, silo body14that houses the feed15, a bottom cone16that angularly directs the feed15to a feed auger18, and a metal frame or stand20supporting the silo off of the concrete base or ground.

The block diagram ofFIG.2and the exploded view ofFIG.3shows the major components of the vibrating energy phase shift measuring apparatus100. In the combined embodiment, the vibrating energy phase shift measuring apparatus100includes both a vibration source110and vibration sensor120which may be combined into a single housing. Alternatively, as shown inFIG.4, separate housings may be used for the vibration source110and vibration sensor120. In the embodiment shown inFIGS.2and3, a single unit is provided that has both the vibration source110and vibration sensor120where they can be either be alternately timed for operation or the microprocessor can selectively control for one aspect of the unit to be switched off so that the unit becomes either a source or a sensor as needed. If the separate packaging is provided for the excitation circuitry from the measurement circuitry, multiple measurement units can be distributed along the container, seeFIG.4, which could potentially lead to higher accuracy measurements.

FIG.3shows the housing200for containing the system components. In this embodiment, the housing200is a metal housing. The preferred embodiment of the packaging includes an alignment and registration feature to minimize variation in placement on the silo10in the field. The housing200includes an upper lid210with a top surface212and a side wall214defining an alignment aperture216. Below the lid is a printed circuit board220containing the electrical components other than the solar panel310, battery330, and antenna520. The housing body230defines a lid aperture232and base aperture234and supports the antenna mount236. In addition, circuit standoffs238are molded into the housing to hold the printed circuit board220.

The base240is secured to the housing body230and retains a base magnet242. In this manner, the base240of the housing200is magnetic to allow for easy attachment to the metal feed towers10. The magnet used for mechanically attaching the system to the metal silo can be replaced with other mechanisms such as clamps, adhesives, bolts, or rivets.

The electrical components300are best understood from the block diagram ofFIG.2, but their placement can be understood by referring toFIG.3. A solar panel310is provided attached to or integrated into the lid210. In this manner, the battery330of the preferred embodiment is charged using the solar panel310. A wind generator can also be used to replace the solar panel to keep the battery charged. The solar panel is electrically connected to a charging interface320that charges the power storage330. The power storage330is commonly referred to as a battery, but a capacitor bank or other energy storage could be utilized. The battery power can also be replaced by power available through a distribution system such as 120V mains or a distributed industrial 24 V DC. These would require different circuit blocks to interface them to the electronics such as an AC/DC converter and a DC/DC converter, respectively.

In this embodiment, the electrical system is powered by a rechargeable battery330which interfaces with the electrical components through a voltage regulator340. The voltage regulator340provides power through electrical connections to the signal amplifier350sensors370,380,390, signal conditioners410,420,430, microprocessor or microcontroller450, and transmitter500. The wireless transmitter could be replaced by a wired transmission such as a 4-20 mA current loop, which is often deployed in industrial environments in the form of a multi-node HART communication system.

The vibration source360for the preferred embodiment is a surface transducer362that is controlled through the interaction of the microcontroller450and a speed controller or signal amplifier364. The surface transducer as the vibration excitation source could be replaced by a vibration motor or an electrically actuated impact hammer.

The electrical components include a set of sensors370,380,390comprising at least one accelerometer390for measuring vibration, but can also include other sensors such as a humidity sensor380and temperature sensor370that can be used to compensate for environmental factors on the vibration signature of the structure10. Additionally, the temperature sensor370and humidity sensor380can be used to ensure that feed is properly stored within acceptable parameters. For example, excessive heat or moisture can be detected by these sensors to indicate decomposition of the feed, the accidentally left open silo top that allows rain into the silo, or other factors that may affect the quality of feed being delivered. The temperature sensor370generates a temperature signal372, the humidity sensor380generates a humidity signal374, and the accelerometer390generates a vibration signal376. The temperature signal372passes through a temperature signal conditioner410to generate a temperature conditioned signal412that is provided to the microcontroller450. The humidity signal374passes through a humidity signal conditioner420to generate a humidity conditioned signal422that is provided to the microcontroller450. The vibration signal376passes through a vibration signal conditioner430to generate a vibration conditioned signal432that is provided to the microcontroller450.

The core of the system is based around a microcontroller450which analyzes the sensor information and sends the processed or raw data to the transmitter500where it is broadcast. The transmitter500includes a wireless radio510using a wireless antenna520that is attached to the housing body230and an appropriate receiver550is used to capture the transmitted signal540.

FIG.5shows the prototype unit and the vibration chart600generating the first signal profile610and the second signal profile620. The first signal profile610includes a first harmonic profile612that includes first peak values614and first peak frequencies616which are indicative of an associated first feed quantity618. The second signal profile620includes a second harmonic profile612that includes second peak values614and second peak frequencies616for an associated second feed quantity618. The Fast Fourier Transform data shown inFIG.5shows an increase in peak resonant frequency from the largest first peak value614above 20,000 at the first peak frequency616of approximately 24 hertz at an estimated twenty eight thousand pounds of feed to the second peak value614between 4000 and 4500 at the second peak frequency616of approximately 42 Hertz at nineteen thousand pounds. Note that this is a shift both in amplitude of the signal profile and in the frequency9fthe signal profile which provides a unique signature for feed weight and volume. Thus, a lower frequency maximum peak is indicative of more feed in the container due to the dampening effect, and the higher peak at this lower frequency is also indicative of more feed in the container concentrating the energy into a lower frequency profile. This can also be understood by viewing the lack of upper harmonics in the 28000 lb feed chart. This profile data can be initially collected to create a reference profile, and the newly measured signal can be compared against either the initially collected profile or a previous signal to measure the change and calculate the current feed supply in the silo.

The legitimacy of the approach has been verified through the embodiment shown inFIG.5. The vibration excitation apparatus was a simple vibrational motor. The housing was a custom designed part that was three dimensionally printed so that the motor could be mounted with a neodymium magnet. The vibration sensor was a three axis accelerometer with an eight kilohertz bandwidth provided with a vibration analyzer package particular to the accelerometer. The computer was used to collect and analyze the vibration data.

The steps for the silo vibration method700include providing702a vibrating energy phase shift measuring apparatus with a vibration source and a vibration sensor, applying 704 mechanical excitation to a rigid feed container, measuring706the vibration response with a vibration sensor, the temperature in the rigid feed container, and the humidity in the rigid feed container, calculating708the frequency spectrum of the vibration response, determining the energy710in the signal from the time or frequency domain, determining the volume712of bulk material based on the frequency spectrum, signal amplitude, and previously obtained calibration data; and transmitting714the calculated information with or without the temperature and with or without the humidity information to be received at a receiver.

From the foregoing, it will be seen that this invention well adapted to obtain all the ends and objects herein set forth, together with other advantages which are inherent to the structure. It will also be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims. Many possible embodiments may be made of the invention without departing from the scope thereof. Therefore, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

When interpreting the claims of this application, method claims may be recognized by the explicit use of the word ‘method’ in the preamble of the claims and the use of the ‘ing’ tense of the active word. Method claims should not be interpreted to have particular steps in a particular order unless the claim element specifically refers to a previous element, a previous action, or the result of a previous action. Apparatus claims may be recognized by the use of the word ‘apparatus’ in the preamble of the claim and should not be interpreted to have ‘means plus function language’ unless the word ‘means’ is specifically used in the claim element. The words ‘defining,’ ‘having,’ or ‘including’ should be interpreted as open ended claim language that allows additional elements or structures. Finally, where the claims recite “a” or “a first” element of the equivalent thereof, such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements.