Patent Description:
This application is related to patent application serial no. <CIT>, which corresponds to <CIT>, claiming benefit to provisional patent application serial nos. <CIT> and serial no.

The aforementioned applications were all assigned to the assignee of the present application, which builds on this family of technology.

This invention relates to a technique for sensing parameters of concrete in a rotating container or drum, e.g., including a slump characteristic.

The measurement of concrete slump in readymix delivery is an important quality parameter that both the supplier and the customer need to know at the point of delivery. This is done most often manually using a cone-shaped instrument, known as an Abram's cone. Recently, there has been growing interest in the real-time measurement of another crucial parameter - entrained air in both central mixers for pre-fabricated concrete, and readymix deliveries.

Several patents have described systems for the use of automated methods for providing a measure of the slump in a concrete delivery truck. These include the use of methods to monitor the power/torque or hydraulic pressure required to drive the drum (<CIT>, <CIT>, <CIT>, <CIT> (see references labeled [<NUM>] - [<NUM>] below), the use of a probe internal to the drum for measuring the resistance to flow in the concrete slurry (<CIT>, <CIT> (see references labeled [<NUM>] and [<NUM>] below) and an approach based on the determination of the slurry surface angle relative to the horizontal plane in a rotating drum mixer, as determined via the as termed 'banking angle' in US patent publication no. <CIT> (see reference labeled [<NUM>] below). Approaches to remotely monitor and communicate the concrete status in real-time have also been described, as in <CIT> (see references labeled [<NUM>] below). <CIT> describes a system and method involving use of a sensor-containing body provided with a sonar emitter and a sonar detector which is mounted and/or rotatably disposed along the longitudinal rotational axis of a concrete mixer drum at the close end, the sensor-containing body being connected to a conduit for introducing water, chemical admixture, gas, and/or cleansing fluid through the closed end of the drum into the mixer drum (see references labeled [<NUM>] below). <CIT> discloses an apparatus comprising a signal processing module configured with at least one processor and at least one memory including computer program code, the at least one memory and computer program code configured, with the at least one processor, to cause the apparatus at least to: receive signaling containing information about a stiffness of a concrete mixture; and determine an average bubble size of gas contained in the concrete mixture, based at least partly on the signaling received (see references labeled [<NUM>] below).

The assignee of the present invention has developed a means of measuring entrained air in wet concrete, which is disclosed in the aforementioned patent application serial no. <CIT> (<NUM>-<NUM>-<NUM>-<NUM>). The measurement device or acoustic probe is called, or known in the industry as, AIRtrac™ or AIRtrac Mobile™. The AIRtrac™ sensor may be permanently installed on a rotating container / concrete mixer drum or on the hatch door of a concrete mixer drum.

Consistent with that disclosed in the aforementioned patent application serial no. <CIT>(<NUM>-<NUM>-<NUM>-<NUM>), and by way of example, <FIG> show the AIRtrac™ sensor, that is generally indicated as <NUM> and may include an acoustic-based air probe like element <NUM>. The acoustic-based air probe <NUM> may include an acoustic source generally indicated as <NUM> (see <FIG>) configured to provide an acoustic signal into a mixture of concrete; and an acoustic receiver generally indicated as <NUM> (see <FIG>) configured to be substantially co-planar with the acoustic source <NUM>, to respond to the acoustic signal, and to provide signaling containing information about the acoustic signal injected into the mixture of concrete. By way of example, the acoustic source <NUM> may consist of an arrangement of parts and components and is best shown in detail in <FIG>. By way of example, the acoustic receiver <NUM> may consist of at least an arrangement of one or more transducers and fills and is best shown in <FIG>.

The acoustic-based air probe <NUM> may include a planar probing surface <NUM> having a first aperture 106a formed therein configured to receive part of the acoustic source <NUM>, including a hardened steel piston <NUM>, as best shown in <FIG>. At the interface with the planar probing surface <NUM>, the hardened steel piston <NUM> is surrounded by a circumferential channel 122a, so as not to be in physical contact with the planar probing surface <NUM>. The planar probing surface <NUM> may include at least one second aperture 106b, 106c formed therein configured to receive at least one part <NUM>', <NUM>" of the acoustic receiver <NUM>. The part <NUM>', <NUM>" are shown as a protective polyurethane rubber member in <FIG>. The planar probing surface <NUM> may be configured as a hardened steel face plate, although the scope of the invention is intended to include using other type or kinds of materials either now known or later developed in the future. The acoustic receivers <NUM> are configured in relation to the center of the hardened steel piston <NUM> of the acoustic source <NUM> and defined by a radius R, as best shown in <FIG>, so that the acoustic receivers <NUM> are arranged and configured substantially on the circumference of a circle defined by the radius R from the center of the hardened steel piston <NUM>.

The acoustic receiver <NUM> may include, or take the form of, a dynamic pressure transducer, as best shown in <FIG>.

In operation, and by way of example, the acoustic receiver <NUM> may be configured to receive acoustic signals, e.g., having a frequency in a range of about <NUM>-<NUM>, including <NUM>, although the scope of the invention is intended to include using other frequencies.

By way of example, the acoustic source <NUM> may include, or take the form of, or be configured as, a floating mass, consistent with that shown in <FIG>.

In <FIG>, the acoustic source <NUM> is shown in the form of a piston module assembly <NUM> having the rigid hardened steel piston <NUM> configured with a channel <NUM> to receive, or be coupled to, a piston shaft <NUM>. The acoustic-based air probe <NUM> has a base plate disk <NUM> that contains the piston module assembly <NUM>, as well as other components in <FIG>. The rigid hardened steel piston <NUM> is enclosed, surrounded and configured to move in relation to a low durometer cast silicone rubber <NUM> and photo-etched flexures <NUM>, so as to provide the floating mass aspect of the acoustic source <NUM>. The low durometer cast silcone rubber <NUM> may also be configured to perform sealing functionality in relation to the mixture of the concrete. The acoustic source <NUM> may also include a vibration isolated actuator block assembly <NUM>, best identified in <FIG>, having a stationary voice coil actuator field assembly <NUM> in combination with a voice coil actuator field assembly <NUM> having an accelerometer transducer configuration. The vibration isolated actuator block assembly <NUM> may be configured to drive and vibrate the piston shaft <NUM>, consistent with that shown in <FIG>, so as to provide the acoustic signal to the mixture of the concrete when the acoustic-based air probe is inserted into the mixture. The apparatus <NUM> may also be configured with signal processing technology (not shown) for driving the acoustic source <NUM>, as would be appreciated by a person skilled in the art.

The acoustic-based air probe <NUM> may include a fluid/media temperature sensor <NUM>, consistent with that shown in <FIG>, configured to provide a temperature reading of the mixture.

The acoustic-based air probe <NUM> may include a voice coil temperature sensor <NUM>, consistent with that shown in <FIG>, configured to provide a temperature reading of the stationary voice coil actuator field assembly <NUM>.

The acoustic-based air probe <NUM> may include two acoustic receivers <NUM>, <NUM>', that may take the form of the two dynamic pressure transducers, consistent with that shown in <FIG>.

The acoustic-based air probe <NUM> may include some combination of a connector/wiring cover plate <NUM>, and various connectors configured in relation to the same, including a pressure sensor no. <NUM> connector <NUM> for providing the signaling in relation to one pressure sensor, a pressure sensor no. <NUM> connector <NUM> for providing the signaling in relation to the other pressure sensor, a voice coil drive connector <NUM> for providing the signaling in relation to the voice coil drive <NUM> (<FIG>), a temperature sensor connector <NUM> for providing the signaling in relation to a temperature, and an accelerometer connector <NUM> for providing the signaling in relation to the voice coil actuator moving coil assembly <NUM> (<FIG>), all shown in <FIG>.

In its broadest sense, the present invention provides a new and unique system for determining a slump characteristic having an acoustic sensor and a signal processor.

The present invention relates to a system according to claim <NUM>. Further embodiments of the invention are given in the dependent claims.

The system may include one or more of the following features:
The acoustic sensor may include PVDF patches or PZT elements.

The PVDF patches or PZT elements may be mounted on an exterior mixing drum wall of the mixing drum.

The PVDF patches or PZT elements may be covered by an outer protective housing/cover, including where the outer protective housing/cover provides external noise protection.

The signal processor is configured to determine the slump characteristic based upon noise characteristic at different spatial locations that indicate differences in the slump of the mixture of slurry.

The vane of the mixing drum may be mounted on an interior wall of the mixing drum at an interior location, and the acoustic sensor is mounted on an exterior wall of the mixing drum at an exterior location corresponding to the interior location.

The acoustic sensor may be configured to sense a first noise characteristic when the concrete is lifted by a vane of the mixing drum and provide first acoustic sensor signaling containing information about when the concrete is lifted by the vane, and sense a second noise characteristic when the concrete flows off the vane and falls back into the mixture and provide second acoustic sensor signaling containing information about when the concrete flows off the vane and falls back into the mixture; and the signal processor may be configured to receive the first acoustic sensor signaling and the second acoustic sensor signaling, and determine the corresponding signaling containing information about the slump characteristic of the mixture of concrete contained in the mixing drum, based upon the first acoustic sensor signaling and the second acoustic sensor signaling received.

The signal processor may be configured to determine the slump characteristic based upon a post exit angle of the vane at which the release occurs.

The signal processor may be configured to determine the slump characteristic based upon noise characteristics at different spatial locations that indicate differences in the slump.

The acoustic sensor may be configured to sense the noise of the concrete flowing off a vane of the mixing drum, and provide first acoustic sensor signal containing information about the noise, and sense a dynamic noise of the remixing of the concrete falling back into the mixture, and provide second acoustic sensor signal containing information about the dynamic noise; and the signal processor may be configured to receive the first acoustic sensor signaling and the second acoustic sensor signaling, and determine the corresponding signaling containing information about the slump characteristic of the mixture of concrete contained in the mixing drum, based upon noise characteristics contained in the first acoustic sensor signaling and the second acoustic sensor signaling received.

The signal processor may be configured to determine a high slump mix when the concrete in the mixture is lifted, then pours back off the vane into the mixture at a low post exit angle, and the noise is characterized by a broad band flow noise.

The signal processor may be configured to determine a low slump mix when the concrete in the mixture is lifted, then pours back off the vane into the mixture at a high post exit angle, and the noise is characterized by discrete noise transients.

The post exit angle may be determined by comparing first acoustic sensor signaling containing information about when the concrete is lifted by a scoop sampler of the mixing drum and second acoustic sensor signaling containing information about when the concrete flows off the scoop sampler and falls back into the mixture.

The scoop sampler may be coated with a hydrophobic polymer.

According to an embodiment not forming part of the claimed invention, the acoustic sensor may include arrays of SONAR patches configured to sense a differential slurry speed at different locations caused by the motion of drum rotation and provide SONAR patch array signaling containing information about the differential slurry speed at different locations; and the signal processor may be configured to receive the SONAR patch array signaling, and determine the corresponding signaling containing information about the slump characteristic of the mixture of concrete contained in the mixing drum, based upon the SONAR patch array signaling received.

The acoustic sensor may be mounted on an outside wall of the mixing drum.

The acoustic sensor may be mounted on an inside wall of the mixing drum.

The acoustic sensor may include an outside acoustic sensor mounted on an outside wall of the mixing drum, and an inside acoustic sensor mounted on an inside wall of the mixing drum.

According to an embodiment not forming part of the claimed invention, the acoustic sensor may include a first SONAR array mounted inside the mixing drum at a first depth and configured to sense a first flow rate of the concrete in the mixture at the first depth, and provide first SONAR array signaling containing information about the first flow rate, and a second SONAR array mounted inside the mixing drum at a second depth that is different than the first depth and configured to sense a second flow rate of the concrete in the mixture at the second depth, and provide second SONAR array signaling containing information about the second flow rate. In addition, the signal processor may be configured to receive the first SONAR array signaling and the second SONAR array signaling, and determine the corresponding signaling containing information about the slump characteristic of the mixture of concrete contained in the mixing drum, based upon the first SONAR array signaling and the second SONAR array signaling received.

The slump characteristic may be based upon a differential flow characteristic sensed and determined.

According to an embodiment not forming part of the claimed invention, the acoustic sensor may include a first acoustic-based sensor and a second acoustic-based sensor configured to sense the speed of sound (SoS) in a mixture of concrete contained in a mixing drum in a plurality of different planes/directions. In addition, the system may also include a sensor housing assembly having a mounting wall configured to mount the sensor housing assembly on an interior wall of the mixing drum, a first sensor wall configured to mount the first acoustic-based sensor to sense a first SoS in the mixture of concrete contained in the mixing drum in a first plane/direction of the plurality of different planes/directions, and a second sensor wall configured to mount the second acoustic-based sensor to sense a second SoS in the mixture of concrete contained in the mixing drum in a second plane/direction of the plurality of different planes/directions.

The system may include, or take the form of, a multi-directional speed of sound (SoS) sensor.

The first wall may be configured to face inwardly towards the axis of rotation; and the second wall may be configured to contact the mixture of concrete contained in the mixing drum on a leading edge facing the direction that the mixing drum is rotating.

The second sensor wall may be obliquely-oriented in relation to the mounting wall and the second sensor wall.

The first acoustic-based sensor may be configured to provide first acoustic-based sensor signaling containing information about a first acoustic signaling sensed at a first frequency.

The first acoustic-based sensor may include a first acoustic transmitter configured to provide first acoustic transmitter signaling at the first frequency; and a first acoustic receiver configured to receive the first acoustic transmitter signaling and provide the first acoustic signaling sensed at the first frequency.

The first acoustic transmitter may be configured to be substantially co-planar with the first acoustic receiver on the first sensor wall.

The second acoustic-based sensor may be configured to provide second acoustic-based sensor signaling containing information about a second acoustic signaling sensed at a second frequency.

The second acoustic-based sensor may include a second acoustic transmitter configured to provide second acoustic transmitter signaling at the second frequency; and a second acoustic receiver configured to receive the second acoustic transmitter signaling and provide the second acoustic signaling sensed at the second frequency.

The second acoustic transmitter may be configured to be substantially co-planar with the second acoustic receiver on the second sensor wall.

According to an embodiment not forming part of the claimed invention, the system may include a first SoS processor configured to receive the first acoustic-based sensor signaling and provide first SoS processor signaling containing information about a first entrained air level that depends on a first SoS determination in the mixture of concrete contained in the mixing drum in the first plane/direction; the second acoustic-based sensor is configured to provide second acoustic-based sensor signaling containing information about a second acoustic signaling sensed at a second frequency; and the system comprises a second SoS processor configured to receive the second acoustic-based sensor signaling and provide second SoS processor signaling containing information about a second entrained air level that depends on a second SoS determination in the mixture of concrete contained in the mixing drum in the second plane/direction.

The system may include a slump factor processor configured to receive the first SoS processor signaling and second SoS processor signaling, and provide slump factor processor signaling containing information about a slump factor of the mixture of concrete contained in the mixing drum.

The slump factor processor may be configured to determine the slump factor based upon a difference between the first SoS and the second SoS as a function of the rotation speed of the mixing drum.

The slump factor processor may be configured to receive drum rotation speed signaling containing information about the rotation speed of the mixing drum and determine the slump factor based upon the rotation speed of the mixing drum.

The slump factor processor may be configured to determine a slump response factor (FSR) for a rotational speed (ω) by multiplying the difference by a square-root of the first SoS measured based upon the equation: <MAT> where c<NUM>(ω) = the second SoS measured at the rotational speed (ω), c<NUM> is the first SoS measured, and ϕ is the Air Void Fraction corresponding to the first entrained air level.

The slump factor processor may be configured to determine the slump response factor (FSR) based upon a calibration for various mix recipes and drum rotation speeds to provide an indicator of a real time slump in the mixture of concrete.

The system may include a <NUM>-axis accelerometer configured to respond to angular positions of the sensor housing assembly at given times, and provide angular position signaling containing information about the angular positions of the sensor housing assembly at the given times.

The sensor may be mounted on a hatch door of the rotating container or drum, as well as other parts of the rotating container or drum.

According to the invention, the signal processor is configured to receive signaling containing information about a noise characteristic of a mixture of a slurry, including concrete, contained in a mixing drum when rotating and sensed by an acoustic sensor mounted on a wall of the mixing drum, and determine corresponding signaling containing information about a slump characteristic of the mixture of concrete contained in the mixing drum, based upon the signaling received.

The drawing includes <FIG>, which are not necessarily drawn to scale, as follows:.

According to some embodiments, and consistent with that shown in <FIG>, the assignee's AIRtrac™ mobile sensor measures air content by actively creating acoustic waves and measuring the speed of the waves in the concrete media. This is accomplished by using a piston to "pulse" the concrete and measuring the amount of time it takes for the pulse to travel through the concrete and be detected by a pressure transducer that is known distance away from the piston, e.g., consistent with that set forth above. This works very well for the determination of the air content of the concrete mixture but these components can also be used to measure other aspects of the concrete. The present disclosure sets forth two additional measurements that can be made and used to determine information about the slurry, including concrete.

One parameter that is often not known is the precise volumetric amount of concrete that is in a concrete truck, particularly after a partial pour has occurred. Some measurement techniques known in the art look at the hydraulic loading of the drum, however this is often inaccurate as it requires knowledge of the exact density of the concrete as well as the knowledge of other parameters such as the air content. Using the AIRtrac™ system a much more direct measurement can be made. This measurement technique utilizes the fact that the AIRtrac™ sensor is submerged under the concrete for part of the drums rotation and then is out of the concrete for the remainder. In addition, the AIRtrac™ device has a <NUM>-axis accelerometer that is used to determine the angular position of the sensor at any given time. The combination of knowing the concrete entry and exit angles along with the geometry of the drum, the volume of the concrete can be calculated. <FIG> shows a diagram of how this can be achieved.

<FIG> shows an approximately half full drum. The AIRtrac™ sensor will enter the concrete at about +<NUM> degrees from vertical and exit at about -<NUM> degrees. This will give an indication that the concrete is occupying about ½ the drum and the volume can be calculated. A simple calculation can be made for other concrete entry/exit angles to yield volume.

The angle of the sensor is always available so the remaining aspect of the measurement is determination of the concrete entry and exit points. Two ways this can be accomplished utilize the pressure transducer. First, a static pressure can indicate when the sensor is under concrete. While in air above the concrete the pressure transducer will show close to <NUM> pressure, but as the senor enters the concrete the weight of the concrete will cause a pressure reading. This reading will increase until the sensor is at the bottom of the drum and then decrease until the sensor emerges from the concrete on the other side. Various analysis techniques including least squares curve fitting can be used to extrapolate the exact entry and exit points of the pressure sensor. A second detection technique can utilize the magnitude of the acoustic signal the pressure sensor sees as it is generated by the piston. Air is highly attenuative to acoustic waves so when the AIRtrac™ is in air the pressure transducer will see very little of the acoustic energy generated by the piston, while once the sensor is in the concrete the signal level will rise dramatically. This can also be used to determine when the AIRtrac™ sensor enters and leaves the concrete within the drum.

A second parameter of the concrete that the AIRtrac™ can determine is the viscosity of the concrete. The viscosity of a fluid is directly related to the ability of the fluid to flow. Therefore, in a rotating container or drum like a concrete truck a low viscosity fluid will remain very level while a very viscous fluid will tend to not flow very well and will ride up the wall of the drum as the drum exits the fluid. <FIG> shows diagrams of the effect.

The amount of the "tilt" of the concrete in the drum will depend on the viscosity of the fluid (or concrete) and the speed of rotation of the drum. The drum rotation speed can be determined by the <NUM>-axis accelerometer and the "tilt" can be determined by the same techniques described above. With knowledge of these parameters along with geometric shape of the drum the concrete viscosity can be determined. Furthermore, with knowledge of the concrete constituents including amount of water, sand, rock and their respective densities, the slump of the concrete can be determined.

According to some embodiments, and consistent with that shown in <FIG>, the assignee's new AIRtrac™ sensor design can be incorporated internal to a drum mixer to simultaneously determine both the entrained air and slump of the concrete slurry, e.g., based on a determination of the speed of sound (SoS) in the slurry in two, or a plurality of planes - termed here a Multi-Direction SoS - MDSoS - sensor. In particular, see <FIG>, which illustrates the two axis concept: Here, the AIRtrac™ sensor unit, as described in the aforementioned patent application serial no. <CIT> (<NUM>-<NUM>-<NUM>-<NUM>), may be used as the basis of the SoS measurement.

The device shown in <FIG> would be internally integrated into a readymix truck drum, via the drum hatch door, for example, as illustrated in <FIG>.

The speed of sound in a concrete mix is a function of the entrained air level, and has been used as the basis of a device for such monitoring purposes in concrete mixes (see the reference labeled [<NUM>] below). Typically, the device emits a sound signal into the concrete slurry mix at a given frequency, set of frequencies, or is scanned over a range of frequencies. This acoustic signal is then detected at a receiver, or a plurality of receivers (e.g., a microphone or pressure transducer) that are physically offset from the transmitter, and the speed of sound in the slurry assessed.

For the relatively low levels of entrained air as typically specified in readymix concrete slurry mixtures, (e.g., less than <NUM>%) - the speed of sound, c, is approximately inversely proportional to the square root of the entrained air level (or Air Void Fraction, (ϕ), as illustrated in <FIG>.

In a configuration such as that shown in <FIG>, with the ready mixer drum loaded with slurry, but stationary, the MDSoS sensor elements (in this case <NUM> units), labeled as AIRtrac™ #<NUM> and AIRtrac™ #<NUM>, will both measure the same SoS in the slurry, e.g., SoS<NUM> = SoS<NUM>. However, when the drum rotates (clockwise as shown here), the slurry ahead of the MDSoS sensor housing will undergo compressive forces due to the flow resistance experienced in moving (flowing) around the housing assembly (as depicted by the slurry flow arrows in <FIG>). These compressive forces will compress the entrained air bubbles in the slurry locally, such that the 'apparent entrained air content' in the slurry immediately ahead of the sensor housing will be lower, and thus the SoS measured higher than that measured by the sensor monitoring the slurry above the sensor housing.

Due to the fact that the slurry will experience lower flow resistance for high slump mixes (high 'workability'), and high resistance for low slump mixes (low 'workability', the compressive forces will be dependent on the slump, or 'workability' of the concrete slurry. Consequently, for a given drum rotation speed, the difference in the SoS monitored for the two AIRtrac™ sensor modules/units will be inversely related to the slump in the concrete. In addition, the compressive forces will be proportional to the drum rotation speed, so this would be required to be monitored to allow for a calibration factor to be attained, which allows the slump factor to be determined at any non-zero rotational speed.

In considering the dependence on the drum speed, it will be realized that the compressional forces due to flow resistance around the sensor housing experienced in the slurry will increase with increased drum rotational speed, thus, higher drum rotational speeds decrease the apparent entrained level in the slurry near the leading edge of the housing, whereas, in principle, the entrained air level measured above the housing will provide the actual entrained air. Consequently, the difference in the SoS measured between the two AIRtrac™ sensor modules will be a function of the drum rotational speed. Therefore, with a given mix slump, the difference in the observed SOS will depend strongly on the drum rotation speed for a low slump mix (stiff mix), whereas for a high slump mix (high workability / low viscosity), the dependence on the drum rotation rate will be low. This dependency is illustrated in <FIG> that shows the modelled dependency of the difference in observed SoS at the two AIRtrac™ sensors for a range of different entrained air values, and at a nominal rotational speeds ω, and 2ω (characterized such that at the rotational speed of ω, the high slump mix experiences a compression pressure at the leading face of the sensor housing of ~ <NUM> Bar, and the low slump experiences a compression pressure at the leading face of the sensor housing of ~ <NUM> Bar). The other parameters - density etc. are typical of the values associated with concrete slurry.

The drum rotational speed thus serves as a modulator of the difference in the SoS values. To utilize this approach, a calibration formula or table would need to be created, allowing the slump to be determined from the difference SoS measurements and for various entrained air mixes. Interestingly, however, multiplying the difference in SoS measurements by the square-root of the entrained air level produces a response graph as shown in <FIG>.

This plot shows a near flat response over the entrained air range of interest in most mix designs (<NUM>% to <NUM>%), and produces a slump response factor FSR (where c<NUM> = SoS<NUM>, and c<NUM> = SoS<NUM>): <MAT> This new factor, is inversely related to the standard slump measurement, but could be calibrated for various mix recipes and drum rotation speeds to provide an indicator of real time slump in the mix.

The mixing of the slurry in a concrete mixer drum is driven by the blades or vanes that create a 'churn' in the slurry, e.g., consistent with that shown in <FIG>.

The primary purpose of the blades is to lift the slurry (or slurry components initially) as the drum rotates. With each rotation, the lifted slurry drops back into the mixer at the bottom of the drum, creating a mixing dynamic and the cycle repeats again.

Once the slurry components are batched and mixed thoroughly, the dynamics of this mixing process will depend on the slump (workability) of the slurry, e.g.;.

The noise characteristics generated by the mixing slurry will also thus be slump dependent.

<FIG> shows a readymix concrete truck having a mixer drum wall with one or more sensors attached thereto. By way of example, the sensors may be mounted to the mixer drum wall with a shield housing with good noise isolation characteristics. The sensors may also have an outer protective housing/cover (which may also provide an external noise isolation. Consistent with that shown in <FIG>, the sensors may include, or take the form of, e.g., PVDF "patches" or PZT elements.

<FIG> shows a mixer drum having mixer vanes configured therein for mixing slurry contained in the mixer drum. Consistent with that shown in <FIG>, the slurry is 'lifted' by the action of the vanes as the drum turns.

The 'lifted' slurry is ultimately released as the drum turns and depending on the slump, it 'flows' off, or 'tumbles' off the vanes and back into the slurry (mixing process).

The slump of the slurry will play a significant role in the dynamics:.

<FIG> shows a mixer drum having mixer vanes configured therein for mixing slurry contained in the mixer drum. The mixer drum also has an acoustic sensor array, e.g., like that shown in <FIG>.

Consistent with that shown in <FIG>, the sensor array may be positioned to detect both the noise of the slurry flowing off the vanes, and the dynamics of the 'remixing'.

The slump of the slurry will impact the noise characteristics.

<FIG> includes <FIG>, which shows an example of the acoustic impact in relation to high slump and low slump. In operation, the 'churn' effect of the vanes is an important component of the slurry mixing process, but the dynamics are slump-dependent.

For a high slump mix like that shown in <FIG>, the slurry is 'lifted' only slightly then 'pours' back off the vanes into the mix at a low ϕ angle as shown.

The acoustic sensor array will sense noise that is a broader band 'flow' noise.

For a low slump mix like that shown in <FIG>, the slurry 'lifted' by the action of the vanes fragments and tumbles off the off the vane back into the slurry at a higher ϕ angle, e.g., when compared to the low ϕ angle shown in <FIG>.

The acoustic sensor array will sense noise that is characterized by more discrete noise transients. <FIG>: Alternatives: Scoop Sampler.

<FIG> shows a mixer drum having scoop samplers configured on its inside wall and a sensor, e.g., like a SONAR patch, mounted on its outside wall. In operation, the angle at which the slurry "flows" from the scoop is a measure of the slump of the slurry.

In particular, the scoops' are added to extract a sample of slurry as the drum rotates.

By way of example, the walls of scoop may be coated with a hydrophobic polymer (e.g., like polyurethane (PU)) to allow clean release of sample.

By way of further example, and according to some embodiments, the scoops may include a 'lip' to create the resistance to flow-out.

Consistent with that set forth herein, and according to some embodiments, the mixer drum may be configured to detect the point (i.e., the drum rotation angle) at which the slurry flows out of the scoop sampler.

Consistent with that shown in <FIG>, the measurement approach may include using a passive acoustic array, e.g., like the SONAR patch shown.

Moreover, the acoustics of this create a frequency or transient type of signature that gives a measure of the concrete slump - use a microphone (or PVDF strip) in AIRtrac™ assembly to monitor.

<FIG> shows a mixer drum having mixer vanes for mixing a slurry contained therein, as well as acoustic patch arrays configured or mounted on the outside wall of the mixer drum. The mixing drum is mounted on a mixing drum mount as shown.

In operation, the motion of the drum rotation creates an effective differential slurry flow speed at different locations along the drum that could be sensed or picked up by the acoustic patch arrays as shown. By way of example, the acoustic patch arrays may include, or take the form of, SONAR type external patch arrays.

Alternatively, and according to some embodiments, the acoustic patch arrays may be positioned internally under one or more PU layers.

By way of example, and according to some embodiments, characteristics at different 'depths' in the slurry, and different drum RPMs, may also be detected and monitored.

<FIG> shows a mixer drum having scoops configured therein, as well as two SONAR arrays <NUM> and <NUM> configured or mounted on the inside of the mixer drum, e.g., at different depths as shown. For example, the SONAR array <NUM> is mounted on the inside wall of the mixer drum at a first depth, while the SONAR array <NUM> is mounted inside of the mixer drum at a second depth. In effect, the two SONAR arrays <NUM> and <NUM> are separated by a standoff depth indicated by an arrow labeled D.

Consistent with that set forth above, the scoops' are added to extract a sample of slurry as the drum rotates.

By way of example, and according to some embodiments, walls of the scoops may be coated with hydrophobic polymer (e.g., like PU) to allow clean release of sample from the scoop.

By way of example, and according to some embodiments, the SONAR array(s) may be used to monitor the slurry flow rate with the drum rotation at the drum surface (e.g., using SONAR array <NUM>), and at one or more standoff depths D into the slurry (e.g., using SONAR array <NUM>).

<FIG> shows a system <NUM> having a sensor (e.g., such as an acoustic-based sensor like element <NUM>, or a PVDF sensor, or a PZT sensor, or a SONAR array sensor) and a signal processor or signal processing module <NUM> for implementing the present invention.

In operation, the sensor <NUM>, or the PVDF sensor, or the PZT sensor, or the SONAR array sensor may be configured to mount on a wall of a mixing drum like that shown in <FIG>, <FIG>, <FIG> and <FIG>, sense a noise characteristic of a mixture of a slurry, including concrete, contained in a mixing drum when rotating, and provide acoustic sensor signaling containing information about the noise characteristic sensed.

The signal processor <NUM> may be configured to receive the acoustic sensor signaling, and determine corresponding signaling containing information about a slump characteristic of the mixture of concrete contained in the mixing drum, based upon the signaling received.

The functionality of the signal processor or processor control module <NUM> may be implemented using hardware, software, firmware, or a combination thereof. In a typical software implementation, the processor module may include one or more microprocessor-based architectures having a microprocessor, a random access memory (RAM), a read only memory (ROM), input/output devices and control, data and address buses connecting the same, e.g., consistent with that shown in <FIG>, e.g., see element <NUM>. By way of example, the input/output devices may be configured to receive the signaling Sin sensed by the sensor <NUM>, the PVDF sensor, the PZT sensor, and provide the signaling Sin to the signal processor <NUM> for further processing. By way of further example, the input/output devices may be configured to receive the corresponding signaling Sout from the signal processor <NUM>, and provide the corresponding signaling Sout.

A person skilled in the art would be able to program such a microprocessor-based architecture(s) to perform and implement such signal processing functionality described herein without undue experimentation. The scope of the invention is not intended to be limited to any particular implementation using any such microprocessor-based architecture or technology.

By way of example, the present invention is disclosed based upon using the assignee's AIRtrac™ sensor. However, the scope of the invention is not intended to be limited to the same. For example, embodiments are envisioned, and the scope of the invention is intended to include, e.g. using other types or kinds of acoustic-based sensors that may be configured to attach inside a rotating container or drum having a known geometry, sense angular positions of the sensor and sense associated entry and exit points when the sensor enters and exits concrete contained in the rotating container or drum, and provide signaling containing information about the angular positions and the associated entry and exit points.

By way of example, the present invention is disclosed based upon using a rotating drum forming part of a concrete mixing truck. However, the scope of the invention is not intended to be limited to the same. For example, embodiments are envisioned, and the scope of the invention is intended to include, e.g. using other types or kinds of rotating containers or drums that may be configured to receive and contain concrete, as well as rotate and mix the concrete.

By way of example, the present invention is disclosed based upon mixing a slurry like concrete using a rotating drum. However, the scope of the invention is not intended to be limited to the same. For example, embodiments are envisioned, and the scope of the invention is intended to include, e.g. processing other types or kinds of slurries, including other types or kinds of slurries that are sensitive to the amount of entrained air contained therein, other types or kinds of or slurries that are mixed and poured from a rotating container or drum.

Means for attaching a sensor inside a rotating container or drum is known in the art, and the scope of the invention is not intended to be limited to any particular types or kinds thereof.

By way of example, the sensor may include a sensor housing that may be fastened inside the rotating container or drum using fasteners like screws.

PVDF technology including PVDF "patches", as well as PZT technology including PZT elements, are known in the art, and the scope of the invention is not intended to be limited to any particular type or kind thereof.

Moreover, one skilled in the art would understand and appreciate how to implement PVDF "patches" and/or PZT elements in order to sense noise characteristic, e.g., consistent with that disclosed herein.

Claim 1:
A system (<NUM>) comprising
an acoustic sensor (<NUM>) mounted on a wall of a mixing drum, configured to sense noise characteristic of a mixture of a slurry, including concrete, contained in the mixing drum when rotating, and provide acoustic sensor signaling containing information about the noise characteristic sensed; and
a signal processor (<NUM>) configured tc determine the slump characteristic based upon noise characteristics at different spatial locations when rotating the mixing drum that indicate differences in the slump of the mixture of slurry,
receive the acoustic sensor signaling, and
determine corresponding signaling containing information about a slump characteristic of the mixture of the slurry, including concrete, contained in the mixing drum, based upon the signaling received.