AU2016427897A1

AU2016427897A1 - Pre-drain unbalance detection in a washing machine

Info

Publication number: AU2016427897A1
Application number: AU2016427897A
Authority: AU
Inventors: Eduardo Jordão Santos De Sá PALMEIRA; Cristiano Candido VALÉRIO
Original assignee: Electrolux do Brasil SA
Current assignee: Electrolux do Brasil SA
Priority date: 2016-10-25
Filing date: 2016-10-25
Publication date: 2019-05-02
Also published as: BR112019008226A2; CN109863266A; BR112019008226B1; WO2018076082A1

Abstract

A method of sensing unbalance in a washing machine due to unbalance of a wash assembly includes filling a tub of the wash assembly with water, agitating contents of the tub, and initiating an unbalance detection spin prior to draining the water from the tub. During at least a portion of the unbalance detection spin, sensor data is obtained from a sensor mounted to a portion of the washing machine. An unbalance parameter is obtained from the sensor data to determine whether a high dynamic unbalance condition is detected. If a high dynamic unbalance condition is detected, the contents of the tub are redistributed by agitating the contents of the tub in the water.

Description

PRE-DRAIN UNBALANCE DETECTION IN A WASHING MACHINE

FIELD OF THE INVENTION

Aspects of the present invention relate to sensing and correcting a dynamic unbalance in a laundry washing machine, e.g., a vertical-rotation-axis washing machine, prior to draining of the wash tub and initiation of a spin phase.

BACKGROUND OF THE INVENTION

Generally, a washing machine washes laundry by applying mechanical forces to the laundry immersed in washing water. The washing machine performs a washing operation for agitating the laundry within the washing water and a rinsing operation for removing detergent and other substances from the laundry. The washing machine extracts water from the moisture-laden laundry following each of these operations by applying centrifugal forces to the laundry via spinning of a wash drum about an axis of rotation, also known as a spinning process or spinning phase.

Unbalance of the wash assembly may be caused by a non-uniform distribution of a load of laundry inside the drum during the spinning process. Excessive unbalance poses various problems in the washing machine, such as collision of the wash assembly with the outer casing, severe vibration resulting in high noise levels, partial deformation of the laundry drum, and mechanical stress of the drum supporting members, i.e. bearings, dampers, and springs, inside the wash assembly. Accordingly, and particularly in vertical-rotation-axis washing machines, where a wash assembly is rotated by an electric drive unit about a substantially vertical axis or about an axis slightly tilted with respect to a vertical axis, steps should be taken to reduce vibration and walk of the machine during the spin cycle.

In that regard, unbalance is often monitored during a spin cycle when an unbalance condition is most readily detected. However, it is difficult to redistribute laundry once the water has been drained from the wash tub, particularly in vertical-axis-rotation washing machines. Accordingly, if an unbalance condition is discovered during the spin cycle, the wash tub must be refilled with water and subjected to a redistribution agitation stroke so that the laundry may be redistributed. Thus, sensing and correcting for an unbalance

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PCT/BR2016/050269 condition prior to draining of the wash tub, such that the laundry may be redistributed when water still remains in the wash tub, would be beneficial.

BRIEF SUMMARY OF SELECTED INVENTIVE ASPECTS

In view of the foregoing, in an aspect, a primary objective of the present invention is to provide a system for monitoring and controlling dynamic unbalance in washing machines, particularly (but not necessarily) verticalrotation-axis washing machines, prior to a spinning phase when water is still pooled in the wash tub.

Specifically, in an aspect, it is an object of the present invention to provide a system for sensing and controlling unbalance of the wash assembly in a vertical-rotation-axis washing machine which prevents collision of the wash assembly with the casing, and, at the same time, reduces vibration, walk of the washing machine, and/or mechanical stress on drum supporting members.

According to an aspect of the present invention, a method is provided of sensing unbalance in a washing machine due to unbalance of a wash assembly. The method includes filling a tub of the wash assembly with water, agitating contents of the tub, and initiating an unbalance detection spin prior to draining the water from the tub. Sensor data is obtained during the unbalance detection spin from a sensor mounted to a portion of the washing machine. An unbalance parameter, e.g., based on a measured acceleration, vibration or displacement, is determined from the sensor data and, if a high dynamic unbalance condition is detected based on the unbalance parameter, the contents of the tub are redistributed.

In some aspects, redistributing the contents of the tub includes stopping the unbalance detection spin and initiating a rebalance agitation of the contents of the tub. Rebalancing the contents of the tub may further include determining if a maximum number of rebalance agitations has been performed and, upon determining that the maximum number of rebalance agitations has been performed, initiating an alert. Determining whether a dynamic unbalance

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PCT/BR2016/050269 condition is detected may include comparing the unbalance parameter to a predetermined threshold value.

According to another aspect of the present invention, a washing machine includes an outer casing and awash assembly housed inside the outer casing. The wash assembly includes a tub housing a drum rotatable about an axis of rotation. The washing machine further includes a drive system which selectively spins the drum about the axis. A control system is operably connected to the drive system and includes a sensor board assembly mounted to a portion of the washing machine. The sensor board assembly includes a sensor for measuring data for indicating a presence of an unbalance condition. The control system is configured to determine a dynamic unbalance parameter prior to draining water from a tub following a wash or rinse process.

This summary is provided to introduce a selection of concepts of the inventive subject matter that are further described below in the detailed description. This summary is not intended to identify essential features or advantages of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Additional features and advantages of various embodiments are further described below.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the invention are illustrated by way of example and not by limitation in the accompanying figures in which like reference numerals indicate similar elements and in which:

Fig. 1 shows a perspective view of a vertical-rotation-axis washing machine according to some aspects of the present invention.

Fig. 2A is a perspective view of a sensor board assembly that may be used in the vertical-rotation-axis washing machine depicted in Fig. 1.

Fig 2B is a close-up perspective view of a portion of a tub of the wash assembly of the vertical-rotation-axis washing machine depicted in Fig. 1, having fixing portions for mounting the sensor board assembly depicted in Fig. 2A thereto.

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Fig. 2C is another perspective view of the vertical-axis-rotation washing machine depicted in Fig. 1 including a close-up view of a portion of the tub having the sensor board assembly depicted in Fig. 2A mounted thereto.

Fig. 3 is a flow diagram showing a method for sensing unbalance in a vertical-rotation-axis washing machine such as the vertical-rotation-axis washing machine depicted in Fig. 1, prior to a spinning phase, when water is still pooled in the wash tub.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Aspects of the present invention are directed to a laundry washing machine unbalance or out of balance (OOB) detection and control system employing a sensor, e.g., a tub-mounted accelerometer. More particularly, some aspects are directed to an OOB detection and control system for verticalrotation-axis washing machines, i.e., top-load washing machines.

Fig. 1 shows one example of an automatic laundry washing machine 100 that may embody various aspects of the invention. Washing machine 100 includes a generally parallelepiped external cabinet or outer casing 102 and an opening 101 in a top wall of casing 102 that provides access to a suspended wash assembly 103 within the casing 102. The washing machine 100 also includes a control panel (not shown) for controlling the various operations of the washing machine 100, and a hinged lid (not shown) which covers the opening 101 during use of the washing machine 100 and which may be swung open to provide top-load access to portions of a wash assembly 103. Casing 102 houses the wash assembly 103, which is suspended within cabinet 102 by a number of shock-absorbing/dampening devices 106, so that a rotation axis R of the wash assembly 103 is substantially vertical (i.e., parallel to a vertical reference axis V shown in Fig. 1). It should be appreciated that in some embodiments the rotation axis R of the wash assembly 103 may be slightly titled with respect to the vertical reference axis V without departing from the scope of this disclosure.

Wash assembly 103 includes a substantially cylindrical tub 108 housing a wash drum 107, which is rotatable inside tub 108 about the axis of rotation R. The wash assembly 103 further includes a central column 105

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PCT/BR2016/050269 mounted on a bottom surface of the drum 107 for facilitating agitation of a load of laundry within the wash assembly 103.

In use, after placing a load of laundry in wash drum 107, along with a suitable type and quantity of laundry detergent, a wash process is initiated by an operator through interaction with the control panel. The process typically begins with a tub fill cycle, wherein water enters wash tub 108 via an inlet hose and through a valve and nozzle (not shown). Water fills the wash tub 108 to a predetermined level, which may depend on a user setting and/or upon the size of the wash load. Once the appropriate/set level is reached, the water supply valve is closed and the washing machine 100 enters a wash cycle comprising a number of sequential stages. For example, the wash cycle may include an agitation process including intermittent rotation of the central column 105 in one or two directions, i.e., starting and stopping of the rotation of the central column 105, to impart an effective wash action and circulation of the wash load.

Upon completion of the wash cycle, wash liquid contained within the drum 107 and/or the wash tub 108 is drained via a central drain pipe (not shown). Next, a spin cycle is initiated in which the wash drum 107 is rotated at a high rate of speed. This rotation of the drum 107 forces wash liquid absorbed by the laundry out of the load, and out of the drum 107 through apertures 116 formed in the side of the drum 107. Notably, agitation involves central column 105 rotating while wash tub 108 remains stationary or idle, whereas a spin cycle involves central column 105 and wash tub 108 moving together at a relatively high speed (e.g., higher than a speed associated with agitation) to extract water from the wash load. The wash load may further be subjected to a rinse cycle, in which the water supply valve is again opened to allow fresh water to enter the wash tub 108, followed by agitation, draining, and spinning of the drum 107 as discussed. The foregoing process is usually repeated for one or more rinse cycles.

During any of the above-discussed operations, the laundry within the wash assembly 103 may become unbalanced. Specifically, unbalance occurs when an uneven distribution of a load of laundry offsets the center of

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PCT/BR2016/050269 mass of wash assembly 103 with respect to the axis of rotation R of drum 107. As the center of mass moves farther away from the center of the wash assembly 103 (i.e., as the unbalance increases), an oscillatory component of the spinning drum 107 increases causing excessive vibration of the wash assembly 103. Because of the aforementioned problems associated with excessive vibration, it is thus beneficial to continually monitor the vibration and/or unbalance of the wash assembly 103 during the spinning phase, and to reduce the spinning speed and/or terminate rotation altogether if the vibration becomes excessive. Accordingly, the movement and/or acceleration of wash assembly 103 may be monitored while water is contained therein to determine whether a spinning phase (e.g., during rinsing) can be safely performed. In case an excessive unbalance condition is present, the laundry in the wash assembly 103 may be agitated while water is still contained therein to eliminate or reduce the unbalance condition, without wasting water and time to re-load and drain water.

If an unbalance condition is detected during the spinning phase, at which point the water and/or wash liquid has been drained from the tub, redistribution of the load of laundry may be very difficult. Often the tub must be refilled with water in order for a redistribution agitation to effectively redistribute the load of laundry. Moreover, unbalance conditions tend to initially arise during the agitation phase; i.e., prior to draining the water from the tub and initiation of the spinning phase. This initial unbalance condition typically worsens in severity during the spinning phase. Thus detection and control of unbalance conditions may be more effective while water is pooled in the tub because redistribution of the laundry load is more easily accomplished, particularly for vertical-rotationaxis washing machines. Accordingly, aspects of the present invention sense unbalance conditions prior to draining the tub and initiating the spin phase such that, e.g., the water still within the tub 108 can be used to redistribute the unbalanced load.

In that regard, aspects of the invention detect vibration or OOB prior to the spinning phase (i.e., while water is still pooled in the tub) using a sensor mounted to a portion of the washing machine. For example, a control

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PCT/BR2016/050269 system including a main controlled 15 and a sensor board assembly 110 may be mounted to wash tub 108. In an embodiment as best seen in Fig. 2A, the sensor board assembly 110 includes an accelerometer 111 configured to create an electrical signal corresponding to acceleration imparted on the accelerometer. Although the following description of the washing machine is described in connection with the accelerometer 111 used to detect the OOB condition, it should be appreciated that in alternative embodiments other suitable sensors (such as a displacement sensor or the like) may be used to detect the OOB condition. Additionally, although the following description of the washing machine is described in connection with the sensor being mounted to the tub 108, it should be appreciated that in alternative embodiments the sensor may be mounted to another portion of the washing machine 100 that can be expected to experience detectable acceleration, displacement or vibration in relation to OOB conditions.

In some embodiments, the accelerometer may sense acceleration of the tub 108 in one direction (e.g., a substantially horizontal or vertical direction); while in other embodiments the accelerometer may sense acceleration along at least two sensing axes. For example, the accelerometer may be a surface micromachined capacitive three-axis accelerometer, such as Freescale MMA8452Q 3-Axis Digital Accelerometer. The accelerometer 111 is mounted onto a circuit board 122 to provide electrical communication between the sensor board assembly 110 and the main controller 115. The accelerometer 111 and circuit board 122 are disposed within assembly housing 124 which is mounted on an outer portion of wash tub 108. In embodiments where the washing machine is a vertical-rotation-axis and where the accelerometer 111 is configured to sense acceleration along more than one sensing axis, one sensing axis may be substantially parallel to the axis of rotation R of drum 107 (i.e., vertical) and at least one sensing axis is orthogonal to the axis of rotation R of drum 107 (i.e., horizontal).

In some embodiments, and as shown in Fig. 2B, the wash tub 108 may include a mounting frame 127 attached to an outer portion of the wash tub

108 between adjacent lateral ribs 120a, 120b on an outer surface of the wash

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PCT/BR2016/050269 tub 108. Mounting frame 127 has screw holes 128 for mounting the sensor board assembly 110 thereto with screws 126. Accordingly, the sensor board assembly 110 may be added to known washing machine tubs at minimal cost and with only minor modifications made to the hardware of the existing wash assembly.

The control system may further include a processing unit (not shown) for receiving sensor data from the sensor board assembly 110 and determining a dynamic unbalance parameter. In embodiments where the sensor board assembly includes an accelerometer, the accelerometer may be configured to sense acceleration along more than one sensing axis, and the processing unit may determine more than one dynamic unbalance parameter; e.g., an acceleration in one direction substantially parallel to the axis of rotation R of drum 107 (i.e., in the vertical direction) and an acceleration in at least one direction substantially orthogonal to the axis of rotation R of drum 107 (i.e., in the horizontal direction). Finally, and returning to Fig. 1, a drive system 112 (e.g., motor) is operably connected to drum 107 to drive a rotation of the drum 107, e.g., for a spinning phase, and main controller 115 is configured to control the drive system 112, e.g, to adjust a spin speed.

In some embodiments, an unbalance parameter may be obtained from data provided by the sensor, e.g., based on a measured acceleration, displacement, or vibration. If the unbalance parameter exceeds a predetermined unbalance threshold, a critical unbalance condition of wash assembly 103 may be determined. The predetermined unbalance threshold may be determined by correlation with an oscillation value resulting when exceeding a critical unbalanced condition from experimental data and thereafter incorporated into control system for a given washing machine model. Further, separate unbalance thresholds may exist for various wash cycles, e.g., a predrain unbalance check, or unbalance monitoring during a spin phase. If an unbalance parameter exceeds the predetermined unbalance threshold, main controller 115 may perform a corrective routine to mitigate or prevent damage from the unbalance condition. In an embodiment, main controller 115 may

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PCT/BR2016/050269 initiate a rebalance agitation if an unbalance condition is detected while water is still pooled in the tub 108, as described herein.

Fig. 3 depicts a flow chart of a method for monitoring and controlling vibration due to a dynamic unbalance in the vertical-rotation-axis washing machine 100 prior to a spinning phase of a wash assembly 103, when water is still pooled in tub 108. The sequence of steps depicted for this method is for illustrative purposes only, and is not meant to limit the method as it is understood that the steps may proceed in a different logical order or additional or intervening steps may be included without detracting from the invention.

The method starts with filling the tub with water 301 and then agitating contents of the tub 310 as part of a wash or rinse phase of a laundry cycle. An unbalance detection spin 320 is initiated upon completion of the agitation step 310, wherein the drum 107 rotates about the axis of rotation R at a preset spin speed for a preset spin duration. In some embodiments, an amount of water may be drained from the tub 108 prior to the unbalance detection spin 320, depending on a number of factors, including but not limited to: a model of the washing machine, an amount of contents, e.g., laundry, in the tub 108, and/or a level of water in the tub 108. During the unbalance detection spin, a sensor, such as an accelerometer a displacement sensor, is mounted to a portion of the washing machine, e.g., the tub 108, to measure one or more parameters indicative of an unbalance condition. Control system obtains the sensor data at step 330.

In some embodiments, the preset spin speed of the unbalance detection spin at step 320 is generally much lower than a full spin phase spin speed. For example, the preset spin speed of the unbalance detection spin may be on the order of 80-120 RPM, while a full spin phase maximum spin speed may be upwards of 1,500 RPM. Furthermore, the preset spin duration of the unbalance detection spin is generally of short duration, e.g., 10-30 seconds, in comparison to a full spin phase. For example, in some embodiments the preset spin duration of the unbalance detection spin is 20 seconds. The preset spin duration may also vary depending on a number of factors such as the washing machine model or type, the particular washing cycle (e.g., heavy soil or

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PCT/BR2016/050269 delicate), and a relative weight of contents in the tub. Sensor data may be obtained at a preset sample rate, which may also vary depending on a number of factors, such as the preset spin duration and/or the preset spin speed. In some embodiments, control system will obtain sensor data at step 330 for only a certain spin speed range or for a certain duration of the unbalance detection spin. For example, sensor data may be obtained at step 330 during a predetermined interval of the unbalance detection spin, such as the final 45 seconds. In another example, sensor data may be obtained at step 330 when a speed of the unbalance detection spin is within a certain range, such as 72 to 120 RPM.

Sensor data is obtained from the sensor until the unbalance detection spin has been determined to be completed, i.e., the unbalance detection spin has run for the preset spin duration, at step 335, or upon obtaining a data value above a first threshold at 333. The sensor data is processed at step 340 by a processing unit of the control system in order to obtain a dynamic unbalance parameter, e.g., a maximum unbalance parameter. Unbalance detection at low speeds with water in the tub may be more difficult due to a lower level of the sensor signal at the low spin speeds. Accordingly, more advanced data processing of the sensor signal may be necessary to obtain an unbalance measure of sufficient precision. For example, processing the raw sensor data may include converting the sensor signal from a time domain to a frequency domain, e.g., by a Fast Fourier Transform (FFT) or a Discrete Fourier Transform algorithm, and obtaining a sensor value peak in the region of the rotating frequency. A filter, such as a low pass filter, a bandpass filter, or the like, may also be applied when processing the raw sensor data, e.g., as an anti-aliasing filter for conditioning the sensor signal and/or for smoothing the sensor signal. Processing the sensor data at step 340 may also include aligning sensor data with a measured spin speed during the unbalance detection spin and cutting the sensor signal, i.e., excluding sensor data in regions corresponding spin speeds outside of a preferred spin speed range. For example, the preferred spin speed range may be a range substantially close to the maximum speed of the unbalance detection spin, such as 72 to 120 RPM.

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Various operating quantities are determined from the processed sensor data in order to quantify dynamic unbalance conditions, such as a maximum unbalance parameter. For example, the maximum unbalance parameter may be based on a measured acceleration, displacement or vibration, depending on the type of sensor employed. In some embodiments, a maximum unbalance parameter corresponds to an unbalance magnitude, e.g., is based only on a component of sensor data of one direction, e.g., horizontal or vertical, and a predetermined threshold value is obtained from a lookup table based on the directional component of the sensor data. Additionally or alternatively, the lookup table may provide predetermine threshold values which vary based on one or more factors, such as the direction in which the sensor is measuring sensor data and/or operating variable of the wash cycle.

Once a maximum unbalance parameter is obtained from the processed data at step 350, a determination is made of whether the maximum unbalance parameter exceeds a predetermined threshold value, i.e., a second threshold, at step 355 (using, e.g., a lookup table, as discussed). If the maximum unbalance parameter exceeds the second threshold value at 355 and/or if sensor data exceeds the first threshold value at 333, then the contents of the tub are redistributed. For example, in some embodiments, redistributing the contents of the tub includes stopping the unbalance detection spin at step 360 and initiating a rebalance agitation of the contents of the tub at step 370 (if a maximum amount of retribution agitations have not already been attempted as will be more fully discussed below in connection with steps 365 and 380) using the water still pooled within the wash tub 108. During the rebalance agitation, intermittent and rapid rotation of the drum 107 occurs in one or two directions,

i.e., starting and stopping of the rotation of the drum 107, to impart a circulation and redistribution of the wash load. Following the rebalance agitation 370, a subsequent unbalance detection spin is initiated and the method restarts at step 320 and a recheck for the presence of an unbalance condition (e.g., whether a subsequently obtained maximum unbalance parameter exceeds a predetermined second threshold value or whether subsequently obtained sensor data exceeds a predetermined first threshold value) is performed.

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If a subsequently obtained maximum unbalance parameter is determined to still exceed the predetermined threshold value at step 355, a rebalance agitation of the contents of the tub 370 may be repeated. Some loads however may not be able to be rebalanced by the agitation routine. Thus, rebalancing the contents of the tub may also include first determining if a maximum number of rebalance agitations have been performed at step 365. If it is determined that the maximum number of rebalance agitations has been performed, an alert to a user is executed at step 380 in order to notify a user to manually redistribute the contents of the wash tub 108 in order to complete the wash cycle. In some embodiments, the wash cycle will stop until a user entry is received associated with restarting the wash cycle (e.g., if the user has manually redistributed the contents of the wash tub 108). In some embodiments, the wash cycle may continue with the unbalance condition still present. For example, rather than executing an alert at 380, the wash cycle may continue at step 399 with a spin cycle even if the maximum number of rebalance agitations has been performed and, if the drum hits the cabinet during the spin, the spin will stop immediately. If a maximum unbalance parameter does not exceed a predetermined threshold value at step 355, the water pooled in the tub 108 is drained at step 390. Subsequently, the wash cycle continues at step 399. In other words, if the unbalance detection was conducted as part of a wash cycle, the wash cycle may continue with a rinse cycle or with a subsequent wash cycle, as appropriate. Similarly, if the unbalance detection was conducted as part of a rinse cycle, the wash cycle may continue with a spin cycle or with a subsequent rinse cycle, as appropriate.

Fig. 4 depicts an exemplary representation of a sensor signal 410 during a washing process in accordance with one or more aspects of the present disclosure. Also depicted is a control flag signal 420 indicating that a spin speed or agitation speed has reached a target. As shown in FIG. 4, after an agitation phase 430, and while there is still water in the tub, an unbalance condition is detected at 440, e.g., based on a sensed acceleration above a threshold, before reaching a target spin speed shown by control flag 420. Detection of an unbalance condition 440 may be indicative of a washing group

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PCT/BR2016/050269 (e.g., tub) hitting the cabinet. The first threshold may be exceeded upon detection of an unbalance condition 440, e.g., by comparing raw sensor data to a preset threshold. Accordingly, the spinning may be stopped before reaching the target spin speed. In other words, for the detection of an unbalance condition 440, processing the sensor signal may not be necessary to detect unbalance, e.g., an acceleration signal that exceeds the first threshold, since the sensor signal is strong enough for the system to detect the issue.

As shown in FIG. 4, after the detection of an unbalance condition at 440, one or more rebalance agitations at 450 may be attempted in order to reduce or eliminate the unbalance condition. For example, after a first rebalance agitation is performed and subsequent unbalance detection detects that there is no longer an unbalance condition, no further unbalance detection spins may be needed. However, where the sensor signal is relatively low, further signal processing, e.g., a Fast Fourier Transform, may be performed to determine if the unbalance is low enough to safely start a spinning phase. When the processed signal is above the second threshold, subsequent rebalance agitations may be performed, otherwise, the water is drained and a spinning phase is performed at 460.

Systems and methods according to aspects of the present invention have the advantage of detecting the presence of a dynamic component of unbalance of the wash assembly prior to a spinning phase when water is still pooled in the wash tub, and so greatly reduces the risk of the washing assembly colliding with the casing during subsequent spinning phases. The benefits include noise and vibration reduction, operating more often at a maximum spin speed and a safer product. Additionally detecting and controlling an unbalance condition prior to a spinning phase when water is still pooled in the wash tub has the added benefit of time savings and water savings.

The invention has been described in terms of particular exemplary embodiments. Numerous other embodiments, modifications and variations within the scope and spirit of the invention will occur to persons of ordinary skill in the art from a review of this disclosure.

Claims

1. A method of sensing unbalance in a washing machine due to unbalance of a wash assembly comprising:

(a) filling a tub of the wash assembly with water;

(b) agitating contents of the tub;

(c) initiating an unbalance detection spin prior to draining the water from the tub;

(d) obtaining sensor data during at least a portion of the unbalance detection spin from a sensor mounted to a portion of the washing machine;

(e) obtaining an unbalance parameter from the sensor data;

(f) determining whether a dynamic unbalance condition is detected based on the unbalance parameter; and (g) upon determining that a dynamic unbalance condition is detected, redistributing the contents of the tub by agitating the contents of the tub in the water.

2. The method according to claim 1, further comprising:

(a) determining if a maximum number of rebalance agitations has been performed; and (b) upon determining that the maximum number of rebalance agitations has been performed, executing an alert.

3. The method according to claim 2, wherein the maximum number of rebalance agitations is determined based on at least one of a washing machine type, a washing cycle selection, and a weight range of the contents in the tub.

4. The method according to claim 1, wherein a spin speed of the unbalance detection spin is less than a spin speed of a full spin phase.

5. The method according to claim 1, wherein determining whether a dynamic unbalance condition is detected includes comparing the unbalance parameter to a predetermined threshold value.

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6. The method according to claim 5, wherein the predetermined threshold value is determined based on at least one of a washing machine model, a washing cycle selection, a weight range of the contents in the tub, and a sensor measurement direction.

7. The method according to claim 1, wherein the sensor is an accelerometer.

8. The method according to claim 7, wherein the accelerometer is mounted to the tub.

9. The method according to claim 1, wherein the sensor is a displacement sensor.

10. The method according to claim 1, wherein obtaining a unbalance parameter from the sensor data includes converting raw sensor data to processed sensor data and obtaining a unbalance parameter from the processed sensor data.

11. The method according to claim 10, wherein converting raw sensor data to processed sensor data includes converting the raw sensor data from a time domain to a frequency domain.

12. The method according to claim 11, wherein converting the raw sensor data from a time domain to a frequency domain includes applying at least one of a Fast Fourier Transform algorithm and a Discrete Fourier Transform algorithm.

13. The method according to claim 10, wherein converting raw sensor data to processed sensor data includes applying a filter.

14. The method according to claim 10, converting raw sensor data to processed sensor data includes excluding sensor data corresponding to a spin speed outside of a preferred spin speed range.

15. The method according to claim 1, wherein the unbalance detection spin includes rotating the drum at a preset spin speed for a preset spin duration.

16. The method according to claim 15, wherein obtaining sensor data during at least a portion of the unbalance detection spin occurs during a predetermined interval of the unbalance detection spin.

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17. The method according to claim 1, further comprising, upon completion of the unbalance detection spin, draining the water from the tub and initiating a full spin phase.

18. A method of sensing unbalance in a wash assembly of a washing machine, wherein the wash assembly includes a tub housing a drum rotatable about an axis of rotation, the method comprising:

(a) initiating an unbalance detection spin of the drum prior to draining water from the tub following a washing process;

(b) obtaining sensor data during the unbalance detection spin from a sensor mounted to a portion of the washing machine;

(c) obtaining an unbalance parameter;

(d) determining whether a dynamic unbalance condition is detected based on the unbalance parameter;

(e) upon determining that a dynamic unbalance condition is detected:

(f) initiating a rebalance agitation of contents of the tub; and (g) initiating a subsequent unbalance detection spin to recheck for a dynamic unbalance condition; and (h) upon determining that a dynamic unbalance condition is not detected:

(i) draining the water from the tub; and (j) initiating a full spin phase.

19. The method according to claim 18, further comprising:

(a) determining if a maximum number of rebalance agitations has been performed; and (b) upon determining that the maximum rebalance agitations have been performed, executing an alert.

20. A washing machine, comprising:

(a) an outer casing;

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PCT/BR2016/050269 (b) a wash assembly housed inside the outer casing including a tub housing a drum rotatable about an axis of rotation;

(c) a drive system for selectively spinning the drum about the axis of rotation; and

5 (d) a control system operably connected to the drive system, the control system including a sensor board assembly mounted to portion of the washing machine and including a sensor for measuring data indicative of an unbalance condition, wherein the control system is configured to:

10 (e) determine a dynamic unbalance parameter during an unbalance detection spin, when water is pooled in the tub following a wash process, (f) determine a presence of a unbalance condition based on the dynamic unbalance parameter, and

15 (g) in response to determining the presence of the unbalance condition, rebalancing contents of the tub by agitating the contents of the tub in the water pooled in the tub.