JP5436945B2 - Weighing device - Google Patents

Description

  The present invention relates to a weighing device, and in particular, a conveying means having a plurality of rotating bodies that rotate to convey an object to be weighed is supported by a load detecting means, and based on a load detection signal obtained from the load detecting means. The present invention relates to a weighing device for obtaining the weight of the object to be weighed.

  An example of this type of weighing device is a weighing conveyor for a weight sorter. That is, in a weighing conveyor for a weight sorter, a conveyor main body as a conveying means is supported by a load sensor such as a load cell as a load detecting means. Then, the weight of the object to be weighed is obtained based on the load detection signal obtained from the load sensor when the object to be weighed is being conveyed by the conveyor body.

  By the way, the conveyor body has various rotating bodies such as a motor and a pulley. That is, these rotating bodies are also supported by the load sensor. When these rotating bodies rotate, a plurality of vibration components corresponding to the respective rotating bodies appear in the load detection signal particularly due to the eccentric load of each rotating body. Needless to say, these vibration components cause a decrease in measurement accuracy. Therefore, in order to improve the measurement accuracy, it is necessary to remove these vibration components. However, the period of each vibration component is the same as the rotation period of the corresponding rotating body, and when converted into a frequency, it is approximately several [Hz] to several tens [Hz]. If such a low-frequency vibration component is to be removed by a normal filter circuit such as a low-pass filter circuit, an excessive response delay occurs, which is inconvenient. Therefore, conventionally, the technique disclosed in Patent Document 1 has been proposed.

  This prior art is applied to, for example, a belt-type weighing conveyor. That is, the belt-type measuring conveyor has two rollers (pulleys) for running an endless belt-like measuring belt and a motor for driving these two rollers as rotating bodies. Specifically, when the motor operates, the driving force is transmitted to one of the rollers via the timing belt. Further, the driving force is transmitted to the other roller via the measuring belt. Thereby, each roller is driven and the measuring belt runs. And the workpiece | work as a to-be-measured object is mounted in this measuring belt, and conveyance of the said workpiece | work is implement | achieved. Furthermore, the weight of the workpiece is obtained based on a weighing signal obtained from a scale as a load detecting means during the conveyance of the workpiece.

  Here, an encoder for encoding the rotation angle is attached to the motor. First, in a prior adjustment operation, a weighing signal when no workpiece is placed on the weighing conveyor (weighing belt) is stored in correspondence with the encoder signal from the encoder. In addition, in the actual operation, the weighing signal stored in advance is subtracted from the weighing signal when the work is placed on the weighing conveyor, corresponding to the encoder signal. As a result, the vibration component caused by the rotating body is removed, and accurate weighing is performed.

JP 2000-337949 A

  However, in the above-described prior art, it is assumed that the motor and each roller as a rotating body rotate in synchronization with each other. Specifically, it is assumed that the motor and each roller are rotating at the same rotation speed (rotation speed), or that the rotation speed of the motor is an integral number of the rotation speed of each roller. The This is because the vibration component caused by each of the rollers, which are other rotating bodies, is also collectively removed based on only the rotation angle of one rotating body called a motor. Therefore, the conventional technique has a problem that it cannot cope with a case where the precondition is not satisfied.

  Even if the above-mentioned premise is satisfied, the vibration component caused by each roller may not be accurately removed. For example, the timing belt that connects the motor and one of the driving-side rollers may be removed as necessary for maintenance or the like. In this case, the timing belt is attached again, but at this time, the relationship between the rotation angles of the motor and the driving side roller (rotational position relationship) is different from that before the timing belt is removed. That is, the phase difference between the vibration component caused by the motor and the vibration component caused by the driving roller changes. Then, although the vibration component caused by the motor is removed in the same manner as before, the vibration component caused by the driving roller is not accurately removed. In addition, the vibration component due to the other-side driven roller cannot be accurately removed. In order to solve this problem, it is necessary to perform adjustment work anew, which requires corresponding labor and cost.

  Furthermore, when attention is paid to the relationship between the rotation angles between the rollers, this may change in the middle. That is, between each roller, a driving force is transmitted from one driving side of each of the rollers to the other driven side by a frictional force with the measuring belt. At that time, the rollers may slip, and the relationship between the rotation angles between the rollers may change. Then, the phase difference between the two vibration components caused by each roller changes, and as a result, at least the vibration component caused by the driven roller is not accurately removed.

  Therefore, the present invention provides a measurement that can remove all vibration components caused by each of these rotating bodies more reliably and accurately than before, regardless of whether or not each rotating body rotates in synchronization with each other. An object is to provide an apparatus.

In order to achieve this object, the present invention provides a load detection signal obtained from a load detecting means, in which a conveying means having a plurality of rotating bodies that rotate to convey an object to be weighed is supported by the load detecting means. In the weighing device for obtaining the weight of the object to be weighed based on the plurality, a plurality of angle detection signals that are attached to the respective rotating bodies and individually detect the rotation angles of the respective rotating bodies and output the rotation angles. comprising a rotation angle detecting means, a memory means in which a plurality of vibration components each rotating body appears in a load detection signal due to rotation is stored in advance in accordance with the angle detection signal for the respective rotating bodies, the To do. Further, the reading means for reading out the vibration component corresponding to each rotating body from the storage means according to the angle detection signal for each rotating body, and the respective vibration components read by the reading means are subtracted from the load detection signal. And vibration component removing means for removing the respective vibration components.

That is, according to the present invention, the conveying means having a plurality of rotating bodies is supported by the load detecting means. And based on the load detection signal obtained from a load detection means when the to-be-measured object is conveyed by the conveyance means, the weight of the said to-be-measured object is calculated | required. Here, due to the rotation of each rotating body, a plurality of vibration components corresponding to the respective rotating bodies appear in the load detection signal. Needless to say, these vibration components cause a decrease in measurement accuracy. Therefore, in order to improve the measurement accuracy, it is necessary to remove these vibration components. Therefore, in the present invention, the rotation angle detecting means attached to each of the rotating body, the rotation angle of the respective rotational bodies can be individually detected. Then, in accordance with the angle detection signals for the respective rotating bodies output from the respective rotating angle detecting means, the vibration components caused by the respective rotating bodies are stored in advance in the storage means, for example, in advance adjustment operation. . Then, in actual operation, the vibration component corresponding to each rotating body is read from the storage means by the reading means according to the angle detection signal for each rotating body. Further, each read vibration component is subtracted from the load detection signal by the vibration component removing means. Thereby, each vibration component is removed from the load detection signal. In other words, vibration components caused by the respective rotating bodies are individually removed on the basis of the rotation angle of each rotating body.

  In the present invention, one of the rotating bodies is a driving source such as a motor, and the other rotating body may be rotated by sequentially transmitting the driving force of the driving source. In this case, only the drive source is first rotated, and the vibration component caused by the drive source is stored in the storage unit based on the load detection signal obtained at this time. Subsequently, the rotating bodies other than the driving source are sequentially rotated according to the order in which the driving force of the driving source is transmitted, and based on the load detection signal obtained each time, the vibration component caused by each rotating body is stored in the storage means. May be stored sequentially.

  As described above, according to the present invention, vibration components caused by the respective rotating bodies are individually removed on the basis of the rotation angle of each rotating body. Therefore, all the rotating bodies are synchronized with each other in order to collectively remove vibration components caused by the respective rollers that are the other rotating bodies on the basis of only the rotation angle of one rotating body called a motor. However, unlike the prior art which is premised on rotating, it is not bound by such a premise. Further, even if a change occurs in the relationship between the rotation angles between the rotating bodies, all vibration components caused by the respective rotating bodies can be accurately removed regardless of this. That is, all the vibration components can be removed more reliably and accurately than in the past.

It is a figure showing a schematic structure of a weight sorter concerning one embodiment of the present invention. It is a block diagram which shows the electrical structure of the indicator in the same embodiment. It is an illustration figure which shows the aspect of each vibration component contained in the analog load detection signal in the embodiment. It is a figure which expands and shows the rotary encoder in the same embodiment. It is a block diagram which shows the notional structure of the initial load detection circuit in the embodiment. It is a timing diagram of each signal containing the vibration component resulting from the motor in the embodiment. It is an illustration figure which shows notionally the correction signal corresponding to a motor in the embodiment. FIG. 3 is a block diagram showing a conceptual configuration of a motor correction signal generation circuit in the same embodiment. It is a timing diagram of each signal containing the vibration component resulting from the drive side pulley in the embodiment. It is an illustration figure which shows notionally the correction signal corresponding to the drive side pulley in the embodiment. It is a block diagram which shows the notional structure of the drive side pulley correction signal generation circuit in the embodiment. It is a timing diagram of each signal including the vibration component resulting from the driven pulley in the same embodiment. It is an illustration figure which shows notionally the correction signal corresponding to a driven pulley in the embodiment. FIG. 3 is a block diagram showing a conceptual configuration of a driven pulley correction signal generation circuit in the same embodiment. It is a block diagram which shows the notional structure of the vibration component removal circuit in the embodiment. It is a flowchart which shows the flow of the vibration component correction | amendment task performed by CPU in the same embodiment. It is a flowchart which shows the subroutine of FIG. 18 is a flowchart showing a subroutine different from FIG. FIG. 19 is a flowchart showing yet another subroutine different from FIG.

  An embodiment of the present invention will be described by taking a weight sorter 10 as an example.

  As shown in FIG. 1, the weight sorter 10 according to the present embodiment includes a weighing conveyor 12, a carry-in conveyor 14 provided in the front stage (left side in FIG. 1) of the weighing conveyor 12, and the weighing conveyor 12. And a carry-out conveyor 16 provided at the rear stage (right side in FIG. 1). As shown by an arrow 20 in FIG. 1, an object 18 to be sorted by the weight sorter 10 is transported from the carry-in conveyor 14 to the weighing conveyor 12, and further from the weighing conveyor 12 to the carry-out conveyor. It is transported to 16. In this series of transport processes, when the object to be weighed 18 is on the weighing conveyor 12, the weight Wm of the object to be weighed 18 is obtained, and strictly speaking, a weight measurement value Wm ′ [k] described later is obtained. Based on the weight measurement value Wm ′ [k], a selection signal Q is generated for selecting whether the weight 18 of the object to be weighed is good or bad, or over / appropriate / light. This sorting signal Q is sent to a sorting device (not shown) attached to the carry-out conveyor 16, and the sorting device sorts the object 18 to be measured based on the sorting signal Q.

  Incidentally, the weighing conveyor 12 includes a so-called belt-type conveyor body 22. That is, the conveyor body 22 includes an endless belt-like conveyor belt 24 and a pair of pulleys 26 and 28 having the same diameter (same outer diameter) for running the conveyor belt 22. The conveyor body 22 is supported by a robust load cell 30 as load detection means. Specifically, the conveyor body 28 is coupled to the movable end (the right end in FIG. 1) of the load cell 30 via a suitable movable side support member 32. The fixed end (the left end portion in FIG. 1) of the load cell 30 is fixed to an appropriate base portion 36 such as a frame of the housing via an appropriate fixed side support member 34.

  Further, one pulley 26 of the conveyor body 22 is coupled to a motor 40 as a driving source via a timing belt 38 as a driving force transmitting means. The motor 40 is also supported by the load cell 30. Specifically, the motor 40 is fixed to an appropriate location on the movable side support member 32. A timing pulley 44 is attached to the rotating shaft 42 of the motor 40, and a timing pulley 46 having the same diameter (the same number of teeth) as that is also attached to the rotating shaft 48 of the one pulley 26. . A timing belt 38 is engaged with these timing pulleys 44 and 48.

  According to this configuration, when the motor 40 operates, the driving force is transmitted to the one pulley 26 via the timing belt 38. Further, the driving force transmitted to the one-side driving pulley 26 is transmitted to the other-side driven pulley 28 via the conveyor belt 24. As a result, the pulleys 26 and 28 rotate, and the conveyor belt 24 travels. Then, when the object 18 is placed on the conveyor belt 24, the object 18 is transported.

  Thus, when the object 18 is being conveyed by the weighing conveyor 12 including the conveyor belt 24, the analog load detection signal Wy (t) (t; time) output from the load cell 30 constituting the weighing conveyor 12 is used. Based on this, the above-described weight measurement value Wy [k] is obtained, and the selection signal Q is created. For this purpose, the analog load detection signal Wy (t) is sent to the indicator 100 that controls the weight sorter 10 as a whole.

  As shown in FIG. 2, the indicator 100 has an amplifier circuit 102, and an analog load detection signal Wy (t) is input to the amplifier circuit 102. The amplification circuit 102 performs amplification processing on the input analog load detection signal Wy (t), and the analog load detection signal Wy (t) after this amplification processing is input to the low-pass filter circuit 104. The low-pass filter circuit 104 removes a noise component in a relatively high frequency band included in the input analog load detection signal Wy (t), for example, a noise component mainly due to an electrical factor of 100 [Hz] or more. The analog load detection signal Wy (t) after the analog filtering processing by the low-pass filter circuit 104 is input to the A / D conversion circuit 106.

  The A / D conversion circuit 106 samples the input analog load detection signal Wy (t) in accordance with the rising edge of the clock pulse CK supplied from the clock pulse (CK) generation circuit 108 as pulse generation means. As a result, the analog load detection signal Wy (t) is converted into a digital load detection signal Wy [k] (k: sampling number). The sampling period by the A / D conversion circuit 106, that is, the period ΔT of the clock pulse CK is, for example, 1 [ms].

The digital load detection signal Wy [k] converted by the A / D conversion circuit 106 is sent to the CPU (Central Processing Unit) via the input / output interface circuit 110.
Processing Unit) 112. The CPU 112 obtains the weight measurement value Wm ′ [k] based on the input digital load detection signal Wy [k], and more specifically, based on a digital load detection signal Wy ′ [k] after digital filtering processing described later. . Further, the CPU 112 creates a selection signal Q based on the weight measurement value Wm ′ [k]. The sorting signal Q is sent to the above-described sorting device via the input / output interface circuit 110.

  The CPU 112 is connected to a memory circuit 114 as a storage unit, and the memory circuit 114 stores a control program for controlling the operation of the CPU 112. Further, the CPU 112 includes an operation key 116 as an instruction input means for inputting various instructions to the CPU 112, a liquid crystal display 118 as an information output means for outputting various information according to the operation of the CPU 112, and the like. They are connected via the input / output interface circuit 110. The operation keys 116 and the display 118 may be integrated with each other, for example, a touch screen.

  Here, when the weight sorter 10 of the present embodiment is operating, in short, focusing on the analog load detection signal Wy (t) when the motor 40 is operating, this analog load detection signal Wy (t). Three vibration components Wa (t), Wb (t), and Wc (t) as shown in an exaggerated manner in FIG. Of these, the vibration component Wa (t) shown in (a) is caused by the eccentric load of the motor 40. Therefore, the period Ta of the vibration component Wa (t) caused by the motor 40 is the same as the rotation period of the motor 40. When this is converted into the frequency fa, it is approximately several [Hz] to several tens [Hz]. is there. The vibration component Wb (t) shown in FIG. 3B is due to the eccentric load of the driving pulley 26, and the vibration component Wc (t) shown in FIG. This is due to the eccentric load. The period Tb (or frequency fb) of the vibration component Wb (t) attributed to the driving pulley 26 is the same as the period Ta (or frequency fa) of the vibration component Wa (t) attributed to the motor 40. Further, the cycle Tc (or frequency fc) of the vibration component Wc (t) caused by the driven pulley 28 is basically the same as the cycle Ta (or frequency fa) of the vibration component Wa (t) caused by the motor 40. In other words, it is the same as the cycle Tb (or frequency fb) of the vibration component Wb (t) caused by the driving pulley 26.

  Strictly speaking, however, the period Tc of the vibration component Wc (t) attributed to the driven pulley 28 is equal to the period Tb of the vibration component Wb (t) attributed to the drive pulley 26 (or the vibration attributed to the motor 40). It is not necessarily the same as the cycle Ta) of the component Wa (t). That is, the cycle Tc of the vibration component Wc (t) caused by the driven pulley 28 and the cycle Tb of the vibration component Wb (t) caused by the drive pulley 26 may be different from each other. This is because although the diameters of the pulleys 26 and 28 are the same as described above, there may be some errors in the diameters. Further, when the diameters of the pulleys 26 and 28 are different from each other in this way, the relationship between the phases (initial phases) φb and φc of the respective vibration components Wb (t) and Wc (t) also changes, and in short, the phase difference (φb -Φc) also changes. This change in phase difference also occurs when each pulley 26 and 28 slips.

  Furthermore, if attention is paid to the relationship between the phase φa of the vibration component Wa (t) caused by the motor 40 and the phase φb of the vibration component Wb (t) caused by the drive pulley 26, this may also change. . That is, the timing belt 38 connecting the motor 40 and the driving pulley 26 may be removed as necessary for maintenance or the like. In this case, the timing belt 38 is newly attached, but at this time, the relationship between the phases φa and φb is different from that before the timing belt 38 is removed, that is, the phase difference (φa−φb) is different. Change. Accordingly, the relationship (φa−φc) between the phase φa of the vibration component Wa (t) caused by the motor 40 and the phase φc of the vibration component Wc (t) caused by the driven pulley 28 is also obtained. Differences occur.

  Needless to say, these vibration components Wa (t), Wb (t) and Wc (t) cause a decrease in measurement accuracy. Therefore, in order to improve the measurement accuracy, it is necessary to remove these vibration components Wa (t), Wb (t) and Wc (t) independently. Therefore, in the present embodiment, the following devices are made.

  That is, if the digital aspects of the vibration components Wa (t), Wb (t), and Wc (t) are Wa [k], Wb [k], and Wc [k], respectively, the weight Wm of the object to be weighed 18 is It is represented by the following formula 1.

<< Formula 1 >>
Wm = α · {Wy [k] −Wp−Wz− (Wa [k] + Wb [k] + Wc [k])}
= Α · {Wy [k] −Wi− (Wa [k] + Wb [k] + Wc [k])}
where Wi = Wp + Wz

  In Equation 1, α is a span coefficient as an adjustment coefficient. Wp is a tare load component applied to the load cell 30 from the beginning like each weight component of the conveyor body 22, the motor 40, the movable support member 32, etc., and Wz is an offset component of the amplifier circuit 102, etc. This is a zero shift component that inevitably exists. The tare load component Wp or the zero shift component Wz includes a load component due to foreign matters such as water droplets and dust adhering to the load cell 30 or the conveyor main body 22 supported by the load cell 30. The tare load component Wp and the zero shift component Wz are combined into one as the initial load component Wi.

  As can be seen from Equation 1, if the span coefficient α, the initial load component Wi, and the vibration components Wa [k], Wb [k], and Wc [k] are known, the digital load detection signal Wy [ k] is substituted to obtain the weight Wm of the object 18 to be weighed. Further, each vibration component Wa [k], Wb [k], and Wc [k] has periodicity as shown in FIG. 3, and each mode includes each vibration component Wa [k], It depends on the rotation angle between the motor 40 that is the source of Wb [k] and Wc [k] and the pulleys 26 and 28.

  Therefore, first, an optical rotary encoder 200 as shown in FIG. 4 is attached to the rotation shaft 42 of the motor 40 in order to detect the rotation angle of the motor 40. Specifically, the rotary encoder 200 includes a rotating disk 202 and two optical sensors 204 and 206. The rotating disk 202 is made of a metal such as aluminum and is fixed to the rotating shaft 42 of the motor 40. In the vicinity of the periphery of the rotating disk 202, a plurality of through holes 208, 208,... Are provided at equal intervals along the periphery. Further, a substantially concave shape is formed at one position of the periphery. A notch 210 is provided. On the other hand, each of the optical sensors 204 and 206 is, for example, a reflective type (photo reflector), and each of the through holes 208, 208,... It is supported by a suitable fixing member 212 so that it can be detected. That is, one photosensor 204 outputs the same number of rectangular pulses as the through holes 208, 208,... Each time the motor 40 (rotating shaft 42) makes one rotation. A one-rotation divided signal Da indicating that the angle (circumference) is divided by the number of the through holes 208, 208,... Is output. The other optical sensor 206 outputs one rectangular pulse each time the motor 40 makes one rotation, that is, outputs a one-rotation signal Sa indicating that the motor 40 has made one rotation. These signals Da and Sa are given to the above-described indicator 100 as angle detection signals, and in detail, are given to the CPU 112 via the input / output interface circuit 110.

Similarly, a rotary encoder 300 is attached to the rotating shaft 48 of the driving pulley 26 as shown in FIG. The angle detection signals (one rotation division signal and one rotation signal) Db and Sb output from the rotary encoder 300 are also given to the indicator 100. Further, the same rotary encoder 400 is attached to the rotating shaft 50 of the driven pulley 28. And this rotary. Angle detection signals Dc and Sc output from the encoder 400 are also given to the indicator 100.

  As described above, the rotary encoders 200, 300, and 400 are attached to the motor 40 and the pulleys 26 and 28, respectively, and a preliminary adjustment operation is performed.

  That is, the adjustment mode is selected by operating the operation key 116 shown in FIG. Then, the timing belt 38 is removed and the conveyor belt 24 is removed. Further, the CPU 112 acquires the digital load detection signal Wy [k] when the motor 40 is in a stopped state and in a so-called no-load state in which the object to be weighed 18 does not exist. The digital load detection signal Wy [k] at this time is expressed by the following equation 2 from the above equation 1.

<< Formula 2 >>
Wy [k] = Wi
∵ Wm = 0, Wa [k] = 0, Wb [k] = 0, Wc [k] = 0

  That is, the digital load detection signal Wy [k] includes only the initial load component Wi. Here, when an initial load component storage command is input by operating the operation key 116, the CPU 112 stores the digital load detection signal Wy [k] in the memory circuit 114 as the initial load component Wi. Strictly speaking, a digital load detection signal Wy ′ [k] after the digital filter processing described below is stored as the initial load component Wi.

  That is, the CPU 114 constitutes an initial load detection circuit 500 as shown in FIG. The initial load detection circuit 500 includes a digital filter circuit 502, and a digital load detection signal Wy [k] is input to the digital filter circuit 502. The digital filter circuit 502 applies an appropriate digital filtering process such as a moving average process to the input digital load detection signal Wy [k], so that a relatively low frequency included in the digital load detection signal Wy [k] is obtained. The noise component of the band, for example, the noise component of 20 [Hz] to 100 [Hz] including the frequency of the commercial AC power supply is removed. The digital load detection signal Wy ′ [k] after the digital filtering process by the digital filter circuit 502 is stored as the initial load product Wi.

  Subsequently, the motor 40 is operated. Since both the timing belt 38 and the conveyor belt 24 are removed as described above, the pulleys 26 and 28 do not rotate and only the motor 40 rotates. Accordingly, the digital load detection signal Wy [k] at this time includes only the initial load component Wi and the vibration component Wa [k] caused by the motor 40. That is, the vibration component Wa [k] caused by the motor 40 is extracted by subtracting the initial load component Wi from the digital load detection signal Wy [k]. Then, based on the extracted vibration component Wa [k], a correction signal Wa [na] for removing the vibration component Wa [k] is generated.

  Specifically, the mutual relationship among the one rotation signal Sa, the one rotation divided signal Da, the clock pulse CK, and the vibration component Wa [k] caused by the motor 40 is illustrated in FIG. As shown. As shown in FIG. 6, the one rotation signal Sa in (a) becomes H (high) level when the notch 210 is detected by one of the optical sensors 204 shown in FIG. 4, and L otherwise. This is a binary signal that becomes (low) level. The one-rotation divided signal Da in (b) becomes H level when any of the through holes 208, 208,... Is detected by the other optical sensor 206, and becomes L level otherwise. It is a value signal. The period Tsa in which the one-rotation signal Sa is at the H level includes any period Tda in which the one-rotation divided signal Da is at the H level. Further, the H level period Tsa of the one rotation signal Sa is longer than the H level period Tda of the one rotation divided signal Da. These signals Sa and Da are given to the CPU 112 as described above.

  The CPU 112 starts from the time point a0 when the rising edge of the clock pulse CK of FIG. 6C first arrives in the H level period Tda of the one rotation division signal Da included in a certain H level period Tsa of the one rotation signal Sb. In the H-level period Tda of the one-rotation divided signal Da included in the H-level period Tsa next to the one-rotation signal Sb, the period up to the time point a0 ′ when the rising edge of the clock pulse CK first arrives is shown in FIG. This is recognized as the period Ta of the vibration component Wa [k] caused by the motor 40. Further, the CPU 112 delimits the period Ta every time the rising edge of the clock pulse CK first arrives in each H level period Tda of the one-rotation divided signal Da, and separates Na intervals na of 0 to Na−1. Set. The number Na of the section na is the same as the number of the through holes 208, 208,.

  Then, for each interval na, the CPU 112 resamples the vibration component Wa [k] in synchronization with the rising edge of the clock pulse CK, and removes the vibration component Wa [k] in the interval na from the average value. Correction signal Wa [na]. The correction signal Wa [na] is conceptually expressed as shown in FIG. 7, for example. The correction signal Wa [na] is stored in the register 120 in the memory circuit 114. Note that the correction signal Wa [na] generated over a plurality of cycles and averaged for each interval na may be stored in the memory circuit 114.

  In order to obtain the correction signal Wa [na], the CPU 112 configures a motor correction signal generation circuit 510 shown in FIG. 8 in terms of software. That is, the motor correction signal generation circuit 510 includes the digital filter circuit 502 shown in FIG. 5, and the digital load detection signal Wy [k] is input to the digital filter circuit 502. The digital load detection signal Wy ′ [k] after the digital filtering process by the digital filter circuit 502 is input to the adder circuit 512. The initial load component Wi previously stored is input to the adder circuit 512, and the adder circuit 512 subtracts the initial load component Wi from the digital load detection signal Wy ′ [k]. Thereby, the vibration component Wa [k] due to the motor 40 is extracted. Further, the vibration component Wa [k] is input to the resampling circuit 514. In addition, the re-sampling circuit 514 receives the one-rotation signal Sa, the one-rotation divided signal Da, and the clock pulse CK for the motor 40, and the re-sampling circuit 514 is used for correction in the manner described above. A signal Wa [na] is generated. The correction signal Wa [na] is stored in the register 120 in the memory circuit 114 in the state shown in FIG.

  After the generation of the correction signal Wa [na], the motor 40 is temporarily stopped and the timing belt 38 is attached. As a result, the motor 40 and the driving pulley 26 are coupled. At this time, since the initial load component Wi increases by the weight of the timing belt 38, the initial load component Wi is stored again. That is, the CPU 112 acquires the digital load detection signal Wy [k] when the motor 40 is in a stopped state and is in a no-load state where the object to be weighed 18 does not exist. Then, when the initial load component storage command is input by operating the operation key 116, the initial load component Wi is newly stored in the same manner as described above.

  Then, the motor 40 is activated. As a result, the motor 40 and the driving pulley 26 rotate. The driven pulley 28 does not rotate. Accordingly, the digital load detection signal Wy [k] at this time includes the initial load component Wi, the vibration component Wa [k] caused by the motor 40, and the vibration component Wb [k] caused by the driving pulley 26. It becomes. That is, by subtracting the initial load component Wi and the vibration component Wa [k] caused by the motor 40 from the digital load detection signal Wy [k], the vibration component Wb [k] caused by the drive pulley 26 is extracted. Is done. Based on the extracted vibration component Wb [k], a correction signal Wb [nb] for removing the vibration component Wb [k] is generated.

  Specifically, the mutual relationship between the one-rotation signal Sb, the one-rotation divided signal Db, the clock pulse CK, and the vibration component Wb [k] caused by the drive-side pulley 26 for the drive-side pulley 26 is expressed as follows. As shown in FIG. 9, for example, as shown in FIG. In the same manner as described with reference to FIG. 6, the CPU 112 corrects the correction signal Wb [nb] for removing the vibration component Wb [k] caused by the drive pulley 26 for each section nb. Is generated. Then, the correction signal Wb [nb] is stored in the register 130 in the memory circuit 114 in the state shown in FIG. The correction signal Wb [nb] may also be averaged over a plurality of cycles.

  In order to obtain the correction signal Wb [nb], the CPU 112 configures a drive pulley correction signal generation circuit 530 shown in FIG. 11 in terms of software. That is, the driving pulley correction signal generation circuit 530 also includes a digital filter circuit 502, and the digital load detection signal Wy [k] is input to the digital filter circuit 502. The digital load detection signal Wy ′ [k] after the digital filtering process by the digital filter circuit 502 is input to the same adder circuit 512 as shown in FIG. The adder circuit 512 subtracts the initial load component Wi from the digital load detection signal Wy ′ [k], and the subtracted signal Wy ″ [k] is input to another adder circuit 532. The circuit 532 reads the correction signal Wa [na] corresponding to the motor 40 from the register 120 shown in FIG. 7 in accordance with the timings of the one-rotation signal Sa and the one-rotation divided signal Da and the clock pulse CK for the motor 40. At the same time, the read correction signal Wa [na] is further subtracted from the signal Wy ″ [k] after subtraction by the adder circuit 512 in the previous stage. Thereby, the vibration component Wb [k] due to the driving pulley 26 is extracted. The vibration component Wb [k] is input to the same resampling circuit 514 as shown in FIG. In addition to the vibration component Wb [k], the re-sampling circuit 514 receives the 1-rotation signal Sb, the 1-rotation divided signal Db, and the clock pulse CK for the driving pulley 26. The re-sampling circuit 514 The correction signal Wb [na] corresponding to the drive pulley 26 is generated in the same manner as when the correction signal Wa [na] corresponding to the motor 40 is generated. The correction signal Wb [nb] is stored in the register 130 in the memory circuit 114 in the state shown in FIG.

  After the generation of the correction signal Wb [nb] corresponding to the driving pulley 26, the motor 40 is stopped again. And the conveyor belt 24 is attached. As a result, the pulleys 26 and 28 are coupled. At this time, since the initial load component Wi further increases by the weight of the conveyor belt 24, the initial load component Wi is stored again. That is, the CPU 112 acquires the digital load detection signal Wy [k] when the motor 40 is in a stopped state and is in a no-load state where the object to be weighed 18 does not exist. Then, by inputting an initial load component storage command by operating the operation key 116, the initial load component Wi is stored again.

  Here, the object to be weighed 18 (sample load) having a known weight Wm is placed on the weighing conveyor 12 (conveyor belt 24) while the motor 40 remains stopped. Then, the digital load detection signal Wy [k] at this time is acquired by the CPU 62. In this case, the following formula 3 based on the above formula 1 is established.

<< Formula 3 >>
Wm = α · {Wy [k] −Wi}
［Wa [k] = 0, Wb [k] = 0, Wc [k] = 0

  In this state, when a span adjustment command is input by operating the operation key 116, the CPU 112 obtains a span coefficient α, that is, performs a span adjustment process so that the expression 3 is satisfied. This span coefficient α is also stored in the memory circuit 114.

  Then, the motor 40 is activated again. As a result, the motor 40 and the pulleys 26 and 28 rotate. Therefore, the digital load detection signal Wy [k] at this time is added to the initial load component Wi, the vibration component Wa [k] caused by the motor 40, and the vibration component Wb [k] caused by the drive pulley 26, and The vibration component Wc [k] resulting from the driven pulley 28 is included. In other words, the initial load component Wi, the vibration component Wa [k] caused by the motor 40, and the vibration component Wb [k] caused by the driving pulley 26 are subtracted from the digital load detection signal Wy [k], thereby being driven. The vibration component Wc [k] due to the side pulley 28 is extracted. Based on the vibration component Wc [k], a correction signal Wc [nc] for removing the vibration component Wc [k] is generated.

  Specifically, the mutual relationship between the one-rotation signal Sc, the one-rotation divided signal Dc, the clock pulse CK, and the vibration component Wc [k] caused by the driven pulley 28 for the driven pulley 28 is expressed as follows. As shown in FIG. 12, for example. The CPU 112 generates a correction signal Wc [nc] for removing the vibration component Wc [k] caused by the driven pulley 28 for each section nc shown in FIG. The correction signal Wc [nc] is also stored in the register 140 in the memory circuit 114 in the state shown in FIG. The correction signal Wc [nc] may also be stored as averaged over a plurality of periods.

  In order to obtain the correction signal Wc [nb] corresponding to the driven pulley 28, the CPU 112 configures the driven pulley correction signal generation circuit 550 shown in FIG. That is, the driven pulley correction signal generation circuit 550 also includes a digital filter circuit 502, and the digital load detection signal Wy [k] is input to the digital filter circuit 502. The digital load detection signal Wy ′ [k] after the digital filtering process by the digital filter circuit 502 is input to the adder circuit 512. The adder circuit 512 subtracts the initial load component Wi from the digital load detection signal Wy ′ [k], and the subtracted signal Wy ″ [k] is input to another adder circuit 532. 7, the correction signal Wa [na] corresponding to the motor 40 is read from the register 120 shown in FIG. 7 in accordance with the timings of the one-rotation signal Sa and the one-rotation divided signal Da and the clock pulse CK for the motor 40. The correction signal Wb [nb] corresponding to the driving pulley 26 is read from the register 130 shown in FIG. 10 in accordance with the timings of the one rotation signal Sb and the one rotation division signal Db and the clock pulse CK for the driving pulley 26. The read out correction signals Wa [na] and Wb [nb] are added to the previous addition circuit 5. Signal after subtraction by 2 Wy "further subtracted from the [k]. Thereby, the vibration component Wc [k] resulting from the driven pulley 28 is extracted. The vibration component Wc [k] is input to the resampling circuit 514. In addition to the vibration component Wc [k], the re-sampling circuit 514 receives the one-rotation signal Sc, the one-rotation divided signal Dc, and the clock pulse CK for the driven pulley 28. The re-sampling circuit 514 The correction signal Wc [nc] corresponding to the driven pulley 28 is generated in the same manner as the generation of the correction signal Wa [na] corresponding to the motor 40 and the correction signal Wb [nb] corresponding to the driving pulley 26. To do. The correction signal Wc [nc] is stored in the register 140 in the memory circuit 114 in the state shown in FIG.

  This completes the prior adjustment operation. Then, the actual operation is performed by selecting the operation mode by operating the operation key 116.

  In this actual operation, the weight measurement value Wm ′ [k] is obtained by the CPU 112 as described above. For this purpose, the CPU 112 configures the vibration component removal circuit 600 shown in FIG.

  That is, the vibration component removal circuit 600 also includes a digital filter circuit 502, and the digital load detection signal Wy [k] is input to the digital filter circuit 502. The digital load detection signal Wy ′ [k] after the digital filtering process by the digital filter circuit 502 is input to the adder circuit 512. The adder circuit 512 subtracts the initial load component Wi from the digital load detection signal Wy ′ [k], and the subtracted signal Wy ″ [k] is input to another adder circuit 532. 7, the correction signal Wa [na] corresponding to the motor 40 is read from the register 120 shown in FIG. 7 in accordance with the timings of the one-rotation signal Sa and the one-rotation divided signal Da and the clock pulse CK for the motor 40. 10, the correction signal Wb [nb] corresponding to the driving pulley 26 is read from the register 130 in accordance with the timings of the one-rotation signal Sb and the one-rotation divided signal Db and the clock pulse CK for the driving pulley 26, Further, the correction signal Wc [nc] corresponding to the driven pulley 28 from the register 140 shown in FIG. Reading is performed in accordance with each timing of the one-rotation signal Sc and the one-rotation divided signal Dc and the clock pulse CK with respect to the driven pulley 28. Then, the read correction signals Wa [na], Wb [nb] and Wc [nc ] Is further subtracted from the signal Wy ″ [k] after subtraction by the adder circuit 512 in the preceding stage. Further, the subtracted signal Wm ″ [k] is input to the multiplication circuit 602. The multiplication circuit 602 multiplies the input signal Wm ″ [k] by the span coefficient α, thereby measuring the weight measurement value Wm. '[K] is generated. That is, according to the vibration component removal circuit 600, the weight measurement value Wm ′ [k] is obtained based on the following equation 4 based on the above equation 1.

<< Formula 4 >>
Wm '[k]
= Α · {Wy [k] −Wi− (Wa [na] + Wb [nb] + Wc [nc])}
≒ Wm

  In order to obtain the weight measurement value Wm ′ [k] based on this equation 4, the CPU 112 is a subroutine of the vibration component correction task shown in FIG. 16 in accordance with the control program stored in the memory circuit 114. This process is executed together with the processes shown in FIGS. Note that the correction signals Wa [na], Wb [nb], and Wc [nc] are already stored in the memory circuit 114.

  That is, when receiving the rising edge of the clock pulse CK, the CPU 112 proceeds to step S1 in FIG. 16 and acquires the digital load detection signal Wy [k]. In step S3, a digital filtering process is performed to obtain a digital load detection signal Wy ′ [k] after the process. Further, the CPU 112 proceeds to step S5 to determine whether or not the weight sorter 10 is operating, in other words, whether or not the motor 40 is operating. Here, when the motor 40 is not operating, the CPU 112 proceeds to step S7.

  In step S7, the CPU 112 performs initial setting. Specifically, “0” is set in each of three flags Fa, Fb, and Fc described later. When this initial setting is completed, the CPU 112 once ends the vibration component correction task.

  On the other hand, if the motor 40 is operating in step S5, the CPU 112 proceeds to step S9. In step S9, preparation is made to remove the vibration component Wa [k] caused by the motor 40, that is, the correction signal Wa [na] for removing the vibration component Wa [k] is shown in FIG. Is read from the register 120 shown in FIG. Details of step S9 will be described later with reference to FIG.

  Then, the CPU 112 proceeds to step S11 to make preparations for removing the vibration component Wb [k] caused by the drive pulley 26, that is, the correction signal Wb [for removing the vibration component Wb [k]. nb] is read from the register 130 shown in FIG. Details of step S11 will also be described later with reference to FIG.

  Further, the CPU 112 proceeds to step S13 and makes preparations for removing the vibration component Wc [k] caused by the driven pulley 28, that is, the correction signal Wc [for removing the vibration component Wc [k]. nc] is read from the register 140 shown in FIG. Details of step S13 will also be described later with reference to FIG.

  Then, the CPU 112 proceeds to step S15, and substitutes the correction signals Wa [na], Wb [nb], and Wc [nc] read in steps S9 to S13 so far into the above-described equation 4. That is, the weight measurement value Wm ′ [k] is obtained by the vibration component removal circuit 600 shown in FIG. The weight measurement value Wm ′ [k] represents the accurate weight value Wm of the object 18 that does not include the vibration components Wa [k], Wb [k], and Wc [k]. Further, the CPU 112 proceeds to step S17, and creates the above-described sorting signal Q based on the weight measurement value Wm ′. Specifically, the weight measurement value Wm ′ is compared with a preset sorting reference value, and the sorting signal Q representing the comparison result is created. Then, the CPU 112 proceeds to step S19, transmits this sorting signal Q to the sorting device, and ends the vibration component correction task.

  In step S9 described above, the CPU 112 executes a subroutine shown in FIG.

  That is, the CPU 112 proceeds to step S101, and determines whether or not the signal level of the one rotation signal Sa described above is H level. Here, when the signal level of the one rotation signal Sa is, for example, H level, the CPU 112 proceeds to step S103. In step S103, it is determined whether or not the signal level of the one-rotation divided signal Da is H level. If the signal level of the one-rotation divided signal Da is H level, for example, the process proceeds to step S105.

  In step S105, the CPU 112 determines whether or not “0” is set in the above-described flag Fa. This flag Fa is an index indicating whether or not the rising edge of the one-rotation divided signal Da is detected. When the flag Fa is “0”, it indicates that the rising edge of the one-rotation divided signal Da has not been detected. In other words, it represents a state waiting for the rising of the one-rotation divided signal Da to arrive. When the flag Fa is “1”, it indicates that the rising edge of the one-rotation divided signal Da is detected, and strictly speaking, it indicates that it is immediately after the rising edge of the one-rotation divided signal Da is detected. . Here, when the flag Fa is “0”, that is, when the rising of the one-rotation divided signal Da is waiting, the CPU 112 proceeds to step S107 and sets the flag Fa to “1”. "Is set. And after execution of this step S107, it progresses to step S109.

  In step S109, the CPU 112 sets (that is, resets) 0 (zero) to the count value na of the counter for counting the interval na described above. In step S111, 0 is also set to the count value Xa of the counter for counting the rising edges of the clock pulse CK. In step S113, the correction signal Wa [na] corresponding to the current section na is read from the memory circuit 114. Furthermore, it progresses to step S115, the said area na is updated, ie, the value of the said area na is incremented only by "1," and it progresses to step S117.

  In step S103 described above, when the signal level of the one-rotation divided signal Da is not H level, that is, when the signal level of the one-rotation divided signal Da is L level, the CPU 112 skips steps S105 to S115. The process directly proceeds to step S117. Further, when “1” is set in the flag Fa in step S105, that is, immediately after the rising of the one-rotation divided signal Da is detected, the process directly proceeds to step S117.

  In step S117, the CPU 112 updates the count value Xa of the counter for counting the rising edges of the clock pulse CK, that is, increments the count value Xa “1”. In step S119, the incremented count value Xa is compared with a preset reference value Ha. The reference value Ha is a determination reference for determining whether or not the H-level period Tda of the one-rotation divided signal Da has elapsed since the rising of the one-rotation divided signal Da has been detected. When this is converted into a period Tha, it is set to be a little longer than the H level period Tda of the one-rotation divided signal Da. In this step S119, for example, when the current count value Xa is equal to or greater than the reference value Ha (Xa ≧ Ha), the CPU 112 detects the rise of the one-rotation divided signal Da and detects the one-rotation divided signal Da. It is determined that the H level period Tda has elapsed, and the process proceeds to step S121. In step S121, “1” is set to the flag Fa, and the subroutine ends. On the other hand, if the current count value Xa is less than the reference value Ha (Xa <Ha), the CPU 112 ends this subroutine without proceeding from step S119 to step S121.

  Steps S119 and S121 are provided in this way because the rising edge of the one-rotation divided signal Da has arrived again due to the rising edge of the clock pulse CK that comes immediately after the rising edge of the one-rotation divided signal Da is detected. This is to prevent being detected as a thing, that is, being erroneously detected. That is, the detection of the rising of the one-rotation divided signal Da is not permitted for a certain period Tha immediately after the rising of the one-rotation divided signal Da is truly detected. By providing the non-permission period Tha, erroneous detection of the rising of the one-rotation divided signal Da is prevented.

  Furthermore, in step S101 described above, when the signal level of the one rotation signal Sa is not the H level, that is, when the signal level of the one rotation signal Sa is the L level, the CPU 112 proceeds to step S123. In step S123, as in step S103 described above, it is determined whether or not the signal level of the one-rotation divided signal Da is H level.

  In step S123, when the signal level of the one rotation division signal Da is, for example, H level, the CPU 112 proceeds to step S125. In step S125, the CPU 112 determines whether or not “0” is set in the flag Fa as in step S105 described above. If “0” is set in the flag Fa, the CPU 112 proceeds to step S127. In step S127, “1” is set in the flag Fa, and the process proceeds to step S111 described above.

  On the other hand, when the signal level of the one-rotation divided signal Da is L level in step S123, the CPU 112 proceeds to step S117 described above. Further, when “1” is set in the flag Fa in step S125, the process directly proceeds to step S117.

  Also in step S11 in FIG. 16, the CPU 112 executes the subroutine shown in FIG. 18 as in FIG. Steps S201 to S227 in FIG. 18 correspond to steps S101 to S127 in FIG. That is, in FIG. 18, Sa, Da, Fa, na, Xa, Wa [na] and Ha in FIG. 17 are Sb, Db, Fb, nb, Xb, Wb [nb] and Hb, respectively (see FIG. 9). Has been replaced. Therefore, a detailed description of FIG. 18 is omitted.

  Also in step S13 in FIG. 16, the CPU 112 executes a similar subroutine as shown in FIG. That is, steps S301 to S327 in FIG. 19 also correspond to steps S101 to S127 in FIG. In short, FIG. 19 shows that Sa, Da, Fa, na, Xa, Wa [na] and Ha in FIG. 17 are Sc, Dc, Fc, nc, Xc, Wc [nc] and Hc, respectively (see FIG. 12). Has been replaced. Therefore, detailed description of this FIG. 19 is also omitted.

  As described above, according to the present embodiment, with reference to the rotation angles of the motor 40 and the pulleys 26 and 28 as the rotating body, the vibration components Wa [k], Wb [k], and Wc resulting therefrom. [K] is removed independently. Therefore, all the rotating bodies are synchronized with each other in order to collectively remove vibration components caused by the respective rollers that are the other rotating bodies on the basis of only the rotation angle of one rotating body called a motor. However, unlike the prior art which is premised on rotating, it is not bound by such a premise. Further, even if a change occurs in the relationship between the rotational angles of the motor 40 and the pulleys 26 and 28, the vibration components Wa [k], Wb [k] and Wc [k] are completely independent of this. ] Can be accurately removed. That is, the vibration components Wa [k], Wb [k], and Wc [k] can be removed more reliably and accurately than in the past.

  In addition, although this embodiment demonstrated the case where this invention was applied to the weighing conveyor 12 for the weight sorter 10, it does not restrict to this. For example, the weighing conveyor 12 is not limited to a belt type, but may be a roller type or a chain type. That is, the present invention functions effectively as long as the weighing device has a configuration in which the rotating body such as the motor 40 and the pulleys 26 and 28 is supported by the load detecting means such as the load cell 30. In addition, a certain amount of the objects to be weighed are discharged from a conveyor scale that calculates the weight (transported amount) of the rose-shaped objects to be continuously transported by the belt conveyor, or from a storage tank that contains subdividable objects to be weighed. In other weighing devices such as the loss-in-weight type quantitative supply device, the rotating body such as a motor is supported by the load detection means, but the present invention can naturally be applied to these.

  In the present embodiment, the reflection type is used as the optical sensors 204 and 206 shown in FIG. 4, but a transmission type (photo interrupter) may be used. Further, instead of the optical sensors 204 and 206, other sensors such as a magnetic sensor and a color sensor may be employed. In this case, it goes without saying that the mode (respective through holes 208, 208,... And notches 210) of the rotating disk 202 needs to be appropriately determined in accordance with the types of these sensors.

  Furthermore, the so-called timing charts shown in FIGS. 6, 9, and 12 are examples only until they are tired, and are not limited to this. That is, as long as the rotation angles of the motor 40 and the pulleys 26 and 28 as a rotating body can be individually detected, it does not matter. In an extreme case, for each of the motor 40 and each of the pulleys 26 and 28, only the one rotation signals Sa, Sb and Sc are captured, and the periods Ta, Tb and Tc of these one rotation signals Sa, Sb and Sc are respectively converted into clock pulses CK. The rotation angles of the motor 40 and the pulleys 26 and 28 may be detected by dividing the signals by short-cycle signals such as the above.

Further, for example, by attaching a marker to one place on the circumference of each of the timing pulley 44 of the motor 40 and the timing pulley 46 of the drive side pulley 26, the gap between the motor 40 and the drive side pulley 26 is set. It is possible to assist the rotation angle relationship to be unchanged. That is, when the timing belt 38 is removed and then attached again, the timing belt 38 is attached so that the respective markers face each other in the same direction. Thereby, the rotational angle relationship between the motor 40 and the driving pulley 26 can be kept constant .

DESCRIPTION OF SYMBOLS 10 Weight sorter 12 Weighing conveyor 18 Object to be weighed 22 Conveyor main body 24 Conveyor belt 26 Drive side pulley 28 Driven side pulley 30 Load cell 38 Timing belt 112 CPU
200, 300, 400 Rotary encoder

Claims (2)

Measuring means for obtaining the weight of the object to be weighed based on a load detection signal obtained from the load detecting means supported by the load detecting means by a conveying means having a plurality of rotating bodies that rotate to convey the object to be weighed. In the device
A plurality of rotation angle detecting means for outputting an angle detection signal representing the rotation angle of each said plurality of rotating bodies of respective rotation angles attached to the plurality of rotating bodies is detected separately,
Storage means in which a plurality of vibration components appearing in the load detection signal due to the rotation of the plurality of rotating bodies are stored in advance according to the angle detection signal for each of the plurality of rotating bodies;
Reading means for reading each of the plurality of vibration components from the storage means according to the angle detection signal for each of the plurality of rotating bodies;
Vibration component removing means for removing each of the plurality of vibration components by subtracting each of the plurality of vibration components read by the reading means from the load detection signal;
A weighing apparatus comprising: One of the plurality of rotating bodies is a driving source, and the other rotates by sequentially transmitting the driving force of the driving source,
The plurality of vibration components are sequentially stored in the storage means based on the load detection signal obtained when the plurality of rotating bodies are sequentially rotated in the order of transmission of the driving force starting from the driving source.
The weighing device according to claim 1.

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