A MULTI-SENSOR BASED MECHANICAL MEASUREMENT SYSTEM AND ITS MEASUREMENT METHOD

Abstract

The invention discloses a multi-sensor-based mechanical measurement system, comprising a sensor, a digital-to-analog conversion unit and a calculation unit; The said sensor include a plurality of sensors, and each of the sensors is connected to the said digital-to-analog conversion unit through a respective analog input channel; The said digital-to-analog conversion unit converts the data and transmits it to the calculation unit; The said computing unit performs a primary calibration on the said sensor corresponding to each of the said analog input channels according to the signal transmitted by each of the analog input channels one by one respectively, and performs secondary calibration according to the primary calibration results of all the said sensors. The invention has the advantages of high precision, high stability, high reliability, low error, low cost, easy maintenance, low failure rate, no need for pairing, strong adaptability to environment and location, light and compact, flexible expansion and the like.

Claims

1. A multi-sensor based mechanical measurement system, characterized in that: Including a sensor (2), a digital-to-analog conversion unit (8) and a calculation unit; The said sensor (2) includes a plurality of sensors, and each of the said sensors (2) is connected to the said digital-to-analog conversion unit (8) through a respective analog input channel (7); The said digital-to-analog conversion unit (8) converts the data and transmits it to the said calculation unit; The said calculation unit performs a separate primary calibration on the sensor (2) corresponding to each of the said analog input channels (7) according to the signal transmitted by each of the said analog input channels (7), and perform secondary calibration according to the primary calibration results of all the said sensors (2).

2. The multi-sensor-based mechanical measurement system according to claim 1, wherein: Also includes the support side (3), one ends of a plurality of the said sensors (2) are all connected to the said support side (3), the other ends of the plurality of said sensors (2) are respectively connected to the plurality of measurement sides (1), and there is no connection between each of the said measurement sides (1).

3. The multi-sensor-based mechanical measurement system system according to claim 2, wherein: A plurality of the said measurement sides (1) are connected through a connection layer (5).

4. The mechanical measurement system based on multiple sensors according to claim 3, is characterized in that: a buffer layer (4) is arranged between the said connection layer (5) and the said measurement side (1).

5. A measurement method based on a multi-sensor mechanical measurement system, characterized in that: Include the following steps: Step 1: The signals of the multiple sensors (2) are respectively transmitted to the digital-to-analog conversion unit (8) through the respective analog input channels (7); Step 2: Perform a calibration on each of the said sensors (2) respectively; Step 3: Perform secondary calibration according to the primary calibration results of all the said sensors (2).

6. A measurement method according to claim 5, is characterized in that: The secondary calibration in the step 3 includes the following steps: Step 3.1: Perform conversion processing of arbitrary complexity on the output measurement value of each sensor (2) after the primary calibration, and use the processing result as the output value; Step 3.2: Accumulate the output value in the step 3.1, and output the superimposed value; Step 3.3: Perform further processing of taring, calibration, and arbitrary complexity transformation on the superimposed value in Step 3.2, and use the processing result as the final result of the secondary calibration.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0060] FIG. 1 is a schematic structural diagram of an existing multi-sensor mechanical measurement system.

[0061] FIG. 2 is a schematic structural diagram of a pressure/weighing system applying an existing multi-sensor mechanical measurement system.

[0062] FIG. 3 is a schematic structural diagram of a tensile force system applying an existing multi-sensor mechanical measurement system.

[0063] FIG. 4 is a “voltage-weight” calibration curve of two sensors in an existing multi-sensor mechanical measurement system.

[0064] FIG. 5 is the optimized calibration curve of “voltage-weight” of two sensors in the existing multi-sensor mechanical measurement system.

[0065] FIG. 6 is a schematic structural diagram of the multi-sensor-based mechanical measurement system of the present invention.

[0066] FIG. 7 is a top view of a pressure/weighing system to which the present invention is applied.

[0067] FIG. 8 is a side view of FIG. 7.

[0068] FIG. 9 is a schematic structural diagram of a tension system applying the present invention.

[0069] FIG. 10 is a schematic structural diagram of another embodiment of the tension system to which the present invention is applied.

[0070] FIG. 11 is a schematic structural diagram of another embodiment of the pressure/weighing system to which the present invention is applied.

[0071] FIG. 12 is a schematic structural diagram of another embodiment of the pressure/weighing system to which the present invention is applied.

[0072] FIG. 13 is a schematic structural diagram of another embodiment of the tension system to which the present invention is applied.

[0073] FIG. 14 is a schematic structural diagram of still another embodiment of the tension system to which the present invention is applied.

DETAILED DESCRIPTION OF PRESENT INVENTION

[0074] Embodiments of the present invention are further described below with reference to the accompanying drawings.

[0075] Please refer to FIG. 6, a multi-sensor-based mechanical measurement system includes a sensor 2, a digital-to-analog conversion unit 8 and a calculation unit; the said sensor 2 include a plurality of sensors, and each of the said sensors 2 is connected to the said digital-to-analog conversion unit 8 through a respective analog input channel 7; the said digital-to-analog conversion unit 8 converts the data and transmits it to the said calculation unit; the said computing unit performs a primary calibration on the said sensor 2 corresponding to each of the said analog input channels 7 according to the signal transmitted by each of the analog input channels 7 one by one respectively, and performs secondary calibration according to the primary calibration results of all the said sensors 2. The computing unit described in the present invention can be a single or any number of digital computing devices with computing capabilities, including but not limited to: computers, single-board computers, embedded industrial control equipment, FPGA, ASIC, DSP equipment, etc.

[0076] Primary calibration means that each sensor 2 has its own dedicated AI channel 7, so that the system can perform accurate calibration for each sensor 2 separately, so as to maintain its precise calibration curve for each sensor 2 respectively. This effectively prevents the inaccuracy and configuration difficulties caused by the superposition (accumulation) of different calibration curves. In addition, problems such as difficulty in sensor pairing in the process of equipment production and maintenance are also avoided.

[0077] Not only that, but assigning one or more AI channels to each sensor 2 (which can be used for other supporting environmental sensors) also ensures that the system can perform the real-time tracking and calibration of deviations caused by various internal and external factors such as temperature, humidity, air pressure, creep, condensation, dust, and fatigue for each sensor respectively. It ensures that each sensor is not only calibrated accurately during initialization, but also maintains its long-term stable and accurate work during subsequent use.

[0078] The process of secondary calibration can range from simple arithmetic accumulation to arbitrarily complex expressions, or arbitrarily complex arithmetic and logical operation codes.

[0079] It should be noted that, unless otherwise specified, the “calibration curve” in this article is a general term. In actual calibration, various methods such as straight lines, piecewise functions, and curves (including but not limited to algorithms such as Lagrangian interpolation, Newton interpolation, etc.) can be used to complete the calibration.

[0080] Preferably, the measurement sides of each sensor in the system are deployed separately, so as to be independent (not connected) to each other. Each sensor constitutes an independent measurement unit, which independently completes the measurement (ADC and calibration) of its own component. This effectively avoids problems such as the eccentric error caused by the mutual stress between the sensors.

[0081] Preferably, generally speaking, a plurality of discretely arranged measuring units do not need any additional mechanism, and can naturally work together well. However, in some special scenarios, for reasons of beauty, equipment protection, or load-friendliness, a flexible or rigidly fixed connection layer can also be added between each measurement unit.

[0082] Please refer to FIG. 7 and FIG. 8, a pressure/weighing system, including the above-mentioned multi-sensor-based mechanical measurement system, also includes a support surface (support side) 3, a plurality of the sensors 2 are arranged on the support surface (support side) 3, and each of the sensors 2 is respectively provided with a measurement surface (measurement side) 1, where the measurement surface (measurement side) 1 is a tray (pallet) in this case.

[0083] Preferably, each of the trays is not connected, which ensures that the measurement surfaces (measurement sides) 1 of each sensor 2 are independent (not connected) of each other, and they each form an independent measurement unit, independently complete the measurement (ADC and calibration) work that belong to their own part of the component.

[0084] For pressure/weighing systems, each sensor 2 is usually fixed downwards (or upwards) on a support surface (support side) 3 individually (respectively), The supporting surface 3 can be any stable surface to which the sensor can be fixed, such as (including but not limited to) a cement/steel concrete surface (such as a cement floor, ceiling); a wood surface; a metal surface; a composite material surface; supports such as reinforced concrete beams/piers; steel beams, keels, etc. for buildings or shelves.

[0085] The sensor 2 can be fixed to the support surface 3 in various ways, such as (including but not limited to) bolts (screws), bayonet, welding, bonding and the like. The sensor 2 can be connected to the support surface 3 by various connecting pieces, such as (including but not limited to) gaskets, angle irons, profiles and the like.

[0086] On the top (or bottom) of the sensor, separate measuring surfaces (measuring sides) for carrying the actual load, such as independent trays (or hooks, hanging rods), are respectively fixed. The sensor 2 and the measurement surface (measurement side) 1 such as a tray can also be connected and fixed in any manner.

[0087] In this way, each sensor 2 in the system constitutes an independent single-sensor weighing unit. In order to ensure independence in its work, each weighing unit should be independent of each other. Specifically, for pressure/weighing units using pallets, the pallet (tray) of each sensor 2 should not come into contact with the pallets of other sensors 2 (other pressure units). Between the two pallets, according to the actual situation, it is usually better to have a distance of 1 to 50 mm.

[0088] However, since the measurement surfaces (measurement sides) 1 such as the trays are independent (not connected); therefore, even if all sensors 2 are fixed on the same support surface 3 and it is clear that the supporting surface 3 does not meet the requirements of absolute rigid body, absolute level and absolute flatness, etc., nor does it affect the individual measurement accuracy of each pressure/weighing cell. This is because they have nothing to do with each other, so various stresses such as levers (seesaws) and mutual torsion as described above will not be generated due to loads or other reasons. Therefore, the overall measurement accuracy is greatly improved.

[0089] However, obviously, the support surface (support side) 3 should not be too soft, so that the measurement surfaces 1 such as the pallet after adding the load contact each other due to the deformation of the supporting surface 3, resulting in interference due to mutual contact (connection). Therefore, the support surface 3 should still be as firm and stable as possible. But obviously, the present invention greatly reduces the requirements on the levelness, flatness and rigidity of the support surface 3.

[0090] Therefore, in addition to the above advantages, the present invention can greatly reduce the size and weight of the measurement system. Traditionally, in order to avoid the stress of various mutual interference between sensors as much as possible, it is necessary to ensure that components such as trays, brackets and chassis are as rigid as possible (deformed as little as possible), and kept it as flat and level as possible. Obviously, the higher the range and the larger the tray (pressure surface) area of the pressure/weighing system, the more difficult it will be to achieve the rigidity and flatness mentioned above (necessarily the use of thicker, stronger materials). Therefore, the existing pressure/weighing system usually increases geometrically in the parameters such as the weight and volume of its products with the increase of its range and tray area.

[0091] For example: a pressure/weighing system with a pallet area of 100×100 cm (1 square meter) and a measuring range of 1000 kg is usually much higher in volume and weight than the sum of nine measuring units with a pallet area of 32×32 cm and a measuring range of 200 kg. Even when the latter is combined, it has a measuring surface of at least 1 square meter and a total capacity of 1800 kg.

[0092] However, the present invention completely avoids the above-mentioned disadvantages by separating the measuring units and then recombining them. That is, every time the range and/or area in the measurement system is doubled, the volume and weight of the system will only increase by the same proportion (doubling) at most, without geometrically (exponentially) increasing its volume and/or weight.

[0093] This not only saves material significantly, reduces production costs and reduces product size. At the same time, it also greatly improves product scalability and adaptability: the linear expansion of elements such as measurement surface and range can be freely realized according to the actual needs of users.

[0094] Please refer to FIG. 9. In a multi-sensor tensile force measurement system consisting of N sensors (of course there are at least N AI channels), each sensor can be connected to a measuring end (measuring side) 1 (each measuring side here is a steel cable) to form independent measuring side units. In this case, each sensor is an independent measuring unit. Each measuring unit can measure its own tensile force component independently of each other.

[0095] Referring to FIG. 10, due to the equivalence of the supporting end (support side) and the measuring end (measuring side) of the tensile force measurement system in the previously described case (please refer to FIG. 3 and its associated background note), We can also replace the supporting side with independent connecting devices such as steel cables. At this time, each sensor is still its own independent measurement unit. Each measuring unit can still measure its own tensile force component independently of each other. And at this time, the equivalence between the support end (support side) 3 and the measurement end (measurement side) 1 in the tensile force measurement system is restored.

[0096] Preferably, a plurality of the measurement sides (1) are connected through a connection layer (5).

[0097] Generally speaking, after each sensor 2 forms an independent measurement unit, they can naturally work well together without any additional mechanism. However, in some special scenarios, for reasons of aesthetics, equipment protection, or load-friendliness, a connection layer 5 may also be added between each measurement unit. As shown in FIG. 11, cover the connecting layer 5 on the tray of some or all of the measurement units. For example: in a set of multi-sensor discrete matrix weighing system with a total area of 100×100 cm consisting of 9 independent measuring units with a tray area of 32×32 cm combined in a 3×3 array, a connection layer can be deployed for aesthetics, small cargo friendly (seamless), protection of the weighing cell, etc. Preferably, the connecting layer 5 is a flexible element, for example, a 100×100 cm rubber pad (or any soft material such as silicone, textile, woven fabric, etc.) is laid on the surface of the tray 1. Although soft materials such as rubber and textiles deployed in a flexible manner such as simple laying can theoretically generate stress (mainly mutual torsion) between different weighing cells, the stress is usually negligible because it is too weak.

[0098] Similarly, in addition to the above-mentioned soft materials, the connecting layer 5 can also be various types of hard large cover plates, such as (including but not limited to) metal plates, PP plates, glass steel plates, plexiglass plates, plywood, MDF, wooden boards, PC board, PVC board, etc., so as to achieve the purpose of protection and beauty similar to the previous one. Preferably, a buffer layer 4 is provided between the connection layer 5 and the tray 1, as shown in FIG. 12, The more recommended deployment method is: firstly lay rubber rings, rubber pads, PVC pads, springs, hydraulic mechanisms or buffer layers of other soft materials on the measurement side (tray, etc.) of each independent measurement unit. Then, on the buffer layer 4, a whole hard cover plate such as a metal plate and a glass fiber reinforced plastic plate is laid. The advantage of this is that since the tray is usually made of hard materials such as metal, the buffer layer 4 in the middle can play a role of buffering and protection between the measurement side 1 such as the tray and the connecting layer 5.

[0099] In addition, this sandwich deployment has two additional benefits:

[0100] 1. A large rigid cover plate (100×100 cm in the example above) can transfer the load relatively more evenly to the individual measuring cells in the system.

[0101] 2. Ring-shaped soft materials such as rubber rings have better mechanical distribution for the force applied to the sensor by the load. After the annular rubber gasket is placed on the square measuring cell tray, it is assumed that the tray is square and the sensor is fixed in the center of the tray. Then when the measuring unit is under load, its longest force arm distance is shortened from half of the square diagonal to the radius of the rubber ring. We know that for a single sensor system, a smaller force arm means a lower eccentric error (this is equivalent to the fact that the load can never be applied to the four corners of the pallet since all four corners have been lifted by the circular rubber pads). This improves the overall accuracy of the system, and also facilitates the creation of independent weighing units with a larger coverage area. Obviously, in addition to squares, the above principles can also be easily extended to any rectangle, parallelogram, ellipse, triangle, trapezoid, pentagon, hexagon and other polygons or other geometric shapes.

[0102] In summary, after adding a sandwich-type flexible connection layer to the whole measurement system, although it is possible to introduce slight mutual stress between the sensors, it can get the advantages of beautiful, seamless (friendly to small goods), durable, easy to maintain, etc. Even due to the reduction of the eccentric error of each weighing cell (shortening of the maximum force arm), the overall measurement accuracy may not decrease but increase.

[0103] Of course, in some special applications, part or all of the weighing cells can also be rigidly fixed. For example, fasten a 100×100 cm steel plate to the 9 measuring units in the above example by means of welding, screws and other fixing means. Obviously, if good rigidity, levelness and flatness cannot be guaranteed, then this fixing method will generate strong stress between the sensors (both lever stress and mutual torsion stress), and these stresses are likely to become more pronounced as the system load is (unbalanced) heavier. But even in this situation, the present invention still has obvious advantages over the prior art:

[0104] 1. It avoids all the disadvantages caused by the junction box (hub), such as poor accuracy, difficult pairing, complex tuning, extra noise, extra faults, and limited number of sensors.

[0105] 2. Even with the stress and eccentric error of a rigidly fixed cover, it is easier and more convenient to perform the calibration via a purely digital software system rather than via a potentiometer in the junction box.

[0106] Further, even if a rigid connection is used, a sandwich structure similar to the previous one can still be adopted, that is, a soft buffer layer 4 made of rubber or other materials is added between each measuring unit tray and the integral cover plate. The buffer layer 4 still has the advantages of absorbing impact force and reducing the eccentric error of each measuring unit. At the same time, the buffer layer can also absorb part of the stress, making the measurement results more accurate.

[0107] Referring to FIG. 13, in the tensile force measurement system, soft or hard flexible or rigid connection layers 5 can also be added to multiple independent measurement units. For example: FIG. 13 shows a way of adding springs, hydraulic mechanisms, etc. to each independent measuring end (measuring side) as a buffer layer 4, and twist it into a loose large steel cable (flexible connection) as the realization of the connection layer 5.

[0108] Please refer to FIG. 14. Both ends of each measuring unit in the tensile force measuring system are respectively fixed on a steel plate by elastic (hydraulic or spring, etc.) suspension, connecting the hard (steel plate) connection layer 5 with the flexible (spring) buffer layer 4.

[0109] Or fix both ends of each measuring unit on the same reinforced concrete column (There are two columns in total, each column has N rigid fixed points to connect the steel cables at the same end of N units: rigid (fixed point) butt rigid (reinforced concrete column) connection layer); Or fix both ends of each measuring unit directly on a rubber plate (A total of two rubber sheets, each with N fixed points connecting the steel cables at the same end of the N units: rigid (fixed point) butt soft (rubber sheet) connection layer) And various means to implement various permutations and combinations of soft/hard materials and flexible/rigid connections.

[0110] Of course, when it is necessary to add a connection layer 5, if there is no clear reason, we still recommend the use of a better performing flexible connection. However, as mentioned above, even with the rigidly connected integral cover, the present invention still has significant advantages over the prior art.

[0111] When the flexible or rigid connection layer 5 on all measurement units is completed, the overall secondary calibration of the system can be performed (if the connection layer is not required, this step can also be skipped and the secondary calibration is performed directly). At this point, after successfully deploying non-goods loads such as rubber pads, springs, steel plates, containers (baskets, etc.), and after the above-mentioned processing steps of scaling, offset, weighted accumulation, and formula transformation, the obtained secondary calibration value is the 0-point weight value of the current system. In other words, the overall superposition value including rubber pads, springs, steel plates, containers, etc. is the overall 0-point value of the current measurement system.

[0112] After determining the 0-point value, we can also determine the overall calibration curve of the system by adding weights continuously. If a rigid connection layer is used, automatic or manual fine-tuning of parameters such as scaling factors, offsets, and weights of each measurement unit may be required to eliminate eccentric errors. Conversely, when a flexible connection layer is used, or no connection layer is used, high accuracy and small errors can often be achieved directly without similar fine-tuning. Of course, in the case of very bad external conditions such as the lack of a sufficiently stable support surface, the support surface is too rugged, the inclination of the measurement surface is large, etc. It may occasionally be necessary to fine-tune some of the measurement units using the method described above, even if no rigid link layer is used.

[0113] It can be seen that the secondary calibration is mainly used for calibration at the overall level of the system, eliminating the additional (non-cargo) load (taring) caused by the connection layer and container, and correct the eccentric error caused by other external factors such as rigid connection layer. The secondary calibration process plays an important role in the final overall accurate measurement of the system.

[0114] A measurement method based on a multi-sensor mechanical measurement system, comprising the following steps:

[0115] Step 1: The signals of the plurality of sensors 2 are respectively transmitted to the digital-to-analog conversion unit 8 through the respective analog input channels 7;

[0116] Step 2: Perform primary calibration on each of the sensors 2 respectively;

[0117] Step 3: Perform secondary calibration according to the primary calibration results of all the sensors 2.

[0118] Different from the primary calibration process, the secondary calibration is a process of inputting the output measurement values of each sensor after the primary calibration, re-calibrating these input values, and finally outputting the overall measurement result value of the system.

[0119] In other words, the input of the secondary calibration is the output of each sensor after the primary calibration process, and the output of the secondary calibration can be used as the measurement result of the whole system for subsequent use and processing.

[0120] The secondary calibration process usually includes the following steps:

[0121] Step 1: Perform scaling and offset processing on the output measurement value of each sensor through primary calibration, and use the processing result as the current output value of the measurement unit to participate in the next calculation. For example: the measurement value of each measurement unit can be converted such as “output value=scaling factor×measurement value+offset”, where “Scale Factor” and “Offset” are configurable items, which are automatically configured by the system or manually configured by the administrator. Of course, the above formula is just an example, and in actual use, the measured value obtained from one calibration can be converted into an output value through any complexity. The conversion method can be either a formula such as the aforementioned “scale factor×measurement value+offset”, or a script or program of arbitrary complexity.

[0122] Step 2: Accumulate the output values of all measurement units in this round. The “accumulate” here is not limited to simple arithmetic addition, but can also be various forms of superposition operations such as (including but not limited to) weighted accumulation, weighted square sum, weighted mean square sum, and weighted accumulated mean square error. For example, a weighted summation algorithm with N measurement units can be defined as follows: superposition value=weight 1×measurement unit 1 output value+weight 2×measurement unit 2 output value+ . . . +weight N×measurement unit N output value.

[0123] Step 3: Perform further processing such as taring, calibration, and arbitrary complexity transformation on the accumulated value generated in the second step, and use the processing result as the final result of the overall secondary calibration of the system. The transformation here can be either a formula such as “scale factor×measurement+offset−tare” above, or a script or program of arbitrary complexity.

[0124] It is easy to see that in the present invention, no matter whether each sensor is connected using discrete fixing, flexible connection surface or rigid connection surface, its functions and precautions of the secondary calibration process are similar, and its main functions are:

[0125] 1. The output values of the individual measuring units are accumulated (superimposed) in some form in a reasonable manner.

[0126] 2. Eliminates and calibrates measurement deviations caused by factors such as: additional stress, errors, imbalances, counterweights introduced by various processes such as “making independent arrangements” and “implementing connection layer”, and abnormal loads (connection layer, containers, etc.).

[0127] In summary, the present invention adopts the design of no junction box (hub) in which each sensor is independently connected to the ADC, combined with discrete calibration, discrete arrangement, secondary calibration, and optional connection layer design, to achieve a mechanical measurement system with the advantages of high accuracy, high stability, high reliability, low error, low cost, easy maintenance, low failure rate, no need for pairing, strong adaptability to environment and location, light and compact, and flexible expansion.

[0128] It should be noted that although the embodiments of the present invention are only directed to pressure/weighing and tension measurement systems, but its principles and ideas are obviously also applicable to various other mechanical measurement systems such as shear force, rotational force, horizontal force, friction force, support force, and load force. Any use of the method described in the present invention in various mechanical measurement systems including but not limited to the above all belong to the protection scope of the present invention.