CN116265640A - Improvements relating to laundry devices and/or control thereof - Google Patents

Abstract

A method of mitigating unbalanced wash load in a washing machine having a horizontal axis drum, comprising: determining an indication of an angular position and optionally a radial position of the OOB mass of the washing machine drum, and controlling a rotational speed of the drum such that when the drum and the OOB mass are rotated, the rotational speed of the drum is varied relative to a normal speed based on the OOB mass such that an outward radial force on the wash load is reduced below an inward radial force and/or gravity.

Description

Improvements relating to laundry devices and/or control thereof

Technical Field

The present invention relates to a method and apparatus for reducing unbalanced mass in a laundry device.

Background

Typically, a washing machine (laundry device) operates in one of two modes.

1. A cleaning mode in which the laundry device drum rotates relatively slowly to tumble and/or agitate the laundry load (i.e., laundry, such as clothes, linens, etc.) and wash liquor within the drum, thereby cleaning the wash load by mechanical action.

2. A spin mode (also referred to as a "spin cycle") in which the drum rotates at a relatively high speed ("spin speed") to remove liquid from the wash load by centrifugal force (e.g., to remove foam after a cleaning phase, to saturate the wash load during a rinsing phase, or to remove as much water as possible during a spinning phase).

During the rotation mode, the force may cause the laundry load to adhere to and rotate with the inner surface of the drum. This may result in an unbalanced (OOB) condition in which the mass of the laundry load is unevenly distributed about the center of rotation of the drum when the laundry device is operated in a spin mode. This is undesirable. Rotating the drum in an unbalanced condition may cause undesirable vibrations and resonances that result in noisy operation and potential damage to the drive and suspension systems of the machine.

It is therefore an object of the present invention to provide an improved method and/or apparatus for reducing unbalance of laundry loads in laundry devices, which method and/or apparatus at least in some way solves one or more of the problems described above and/or at least provides the public with a useful alternative.

Disclosure of Invention

It is an object of the present invention to provide a method and/or apparatus for reducing unbalanced mass in a laundry device.

The present invention may include a method of mitigating unbalanced wash load in a washing machine having a horizontal axis drum, the method comprising: determining an indication of an angle and optionally a radial position of the OOB mass of the washing machine drum, and controlling a rotational speed of the drum such that when the drum and the OOB mass are rotated, the rotational speed of the drum varies based on the OOB mass relative to a normal speed such that an outward radial force on the wash load is reduced below an inward radial force and/or gravity.

Optionally, the rotational speed of the drum varies by less than one revolution of the drum.

The present invention may include a method of reducing unbalanced wash load in a washing machine having a horizontal axis drum, the method comprising:

an indication of OOB mass of a washing machine drum is determined, and a rotational speed of the drum is controlled such that when the drum and OOB mass rotate, the rotational speed of the drum varies relative to a normal speed based on the OOB mass within one revolution of the drum such that an outward radial force on the wash load is reduced below an inward radial force and/or gravity.

Optionally, determining an indication of OOB quality includes determining an angular position of the OOB quality.

Optionally, wherein the rotational speed of the drum varies based on the OOB quality and/or the angular position of the wash load.

Optionally, the OOB quality and/or the angular position of the wash load is determined based on time and/or the angular position of the drum as the drum rotates.

Optionally, the rotational speed of the drum is also reduced based on the radial position of the OOB mass.

Alternatively, a control signal having a different profile from the normal control signal is used to control the rotational speed of the drum.

Optionally, the control signal is based on the following changes when the drum rotates:

time; and/or

Angular position of the drum.

Optionally, the control signal varies as the drum rotates based on the OOB quality and/or the angular position of the wash load.

Optionally, the control signal for controlling the rotation speed of the drum includes:

angular start position/angular span/angular stop position of rotation deceleration;

the slope of the control signal may determine the speed of the speed decrease and/or the radial extent of the target area.

The amplitude of the control signal may determine how much the speed is reduced and/or the radial extent of the target area.

Optionally, the control signal profile generates a rotational speed profile of the rotating drum that generates a target zone and redistributes the OOB quality and/or wash load in the target zone.

Optionally, the target region includes an angular span and a radial extent.

In another aspect, the invention may include a laundry device comprising: the washing machine includes a drum, a motor to rotate the drum, one or more sensors, and a controller to receive input from the sensors and to control the motor to rotate the drum, wherein the controller is configured to mitigate unbalanced washing loads according to one or more methods described herein.

In another aspect, the invention may include a method of reducing load imbalance of laundry in a washing machine having a horizontal axis drum, the method comprising the steps of:

rotating the drum above a satellite speed (which is optionally a constant speed) of the laundry load; and

the drum speed is changed by sequentially decreasing the drum speed and then increasing the drum speed to below the satellites speed and then above the satellites speed within a single rotation of the drum, thereby selectively dropping the laundry load in the drum under the force of gravity.

Optionally, the drum speed is reduced to a speed below the satellite speed at a faster rate than the drum speed is subsequently increased to a speed above the satellite speed.

Optionally, the method further comprises the steps of:

a position (optionally an angular position) of the unbalanced mass of the unbalanced laundry load is determined.

Optionally, the step of varying the drum speed causes the rotation of the drum below the satellite speed to coincide with the position of the unbalanced mass in its rotation about the horizontal axis of the drum at, near or past a high point.

Optionally, the method further comprises the steps of:

determining a target area having an angular extent of angular position relative to the unbalanced mass, and optionally a radial extent relative to the radius of the drum; and wherein the drum speed is changed by sequentially decreasing and then increasing the drum speed to below and then above the satellites speed within a single rotation of the drum to selectively drop the laundry load located in the target area under the force of gravity.

Optionally, the angular extent of the target region is between about 0-90 degrees in either direction relative to the position of the unbalanced mass; or alternatively, between about 0-45 degrees, about 0-30 degrees, about 0-15 degrees, or about 0-5 degrees in either direction relative to the unbalanced mass.

Optionally, the radial extent of the target area is between about 25-100% of the radius of the drum; or alternatively between about 40-100%, about 60-100%, about 80-100%, or about 90-100% of the radius of the drum.

Optionally, one or more selected from below is used as an input from which the location of the unbalanced mass is determined.

a. Motor torque, power, current, speed, or voltage; and/or

b. Time (relative to a reference time point); and/or

c. Drum speed, drum angular position, drum linear acceleration, and/or drum angular acceleration.

Optionally, the location of the unbalanced mass is determined using:

d. sensor data, optionally selected from one or more data from an accelerometer or gyroscope; and/or

e. Motor data, optionally selected from one or more of motor torque, power, current, speed, or voltage.

Alternatively, the location of the unbalanced mass is determined using only motor data.

Optionally, during the step of varying the drum speed by sequentially reducing the drum speed and then increasing the drum speed below the satellites speed and then above the satellites speed, the rotation speed of the drum is controlled using a control signal having a different profile than the previous normal and/or constant control signal profile, and optionally having a pulse profile.

Optionally, the control signal varies based on one or more selected from the group consisting of:

f. motor torque, power, current, speed, or voltage; and/or

g. Time (relative to a reference time point); and/or

h. Drum speed, drum angular position, drum linear acceleration, and/or drum angular acceleration; and/or

i. The mass of the laundry load; and/or

j. The size/diameter of the drum;

optionally, the control signal comprises one or more selected from the group consisting of:

k. angular start position/angular span/angular stop position of rotation speed decrease and subsequent speed increase;

start and/or end of the time of the decrease in rotational speed and subsequent increase in speed (relative to a reference point in time);

m. slope or rate of rotation speed decrease followed by rotation speed increase; and/or

n. the magnitude or amplitude of the increase in rotational speed and subsequent increase in speed.

Optionally, the control signal profile generates a rotational speed profile of the rotating drum that selectively drops the laundry load in the drum under gravity; and

optionally, wherein the control signal profile generates a rotational speed profile of the rotating drum that selectively drops the laundry load in the target area under gravity.

In another aspect, the invention may be included in a laundry device comprising:

the rotating drum is provided with a rotating shaft,

a motor for rotating the drum,

optionally one or more sensors, and

a controller receiving input from the motor and/or the sensor (if present) and controlling the motor to rotate the drum,

wherein the controller is configured to mitigate unbalanced wash loads according to one or more methods described herein.

The numerical ranges disclosed herein (e.g., 1 to 10) also include all rational numbers (e.g., 1, 1.1, 2, 3, 3.9, 4, 5, 6, 6.5, 7, 8, 9, and 10) within that range as well as any rational number ranges within that range (e.g., 2 to 8, 1.5 to 5.5, and 3.1 to 4.7).

The term "comprising" as used in this specification means "consisting at least in part of … …". Related terms such as "comprising (comprise, comprised)" should be interpreted in the same manner.

The invention may also consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more of said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which the invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

Drawings

Embodiments will be described below with reference to the following drawings, in which:

fig. 1A, 1B and 1C schematically illustrate a drum of a laundry device in an unbalanced (OOB) state.

Fig. 2A, 2B illustrate a schematic or model of a drum of the laundry device in an OOB state as shown in any one of fig. 1A, 1B or 1C.

Fig. 3 schematically shows a laundry device for performing the method of the present embodiment.

Fig. 4 shows an exemplary laundry device for performing the method of the present embodiment, having a cross-section through the cabinet of the laundry device.

Fig. 5 illustrates a cross-section of a drum and drive motor assembly of an exemplary laundry device for performing the method of the present embodiment.

Fig. 6A-6E illustrate various relative angular positions of OOB quality of a satellite laundry load.

Fig. 7 illustrates an exemplary cyclic variation of a driving torque of a motor rotating a drum of a laundry device with time.

Fig. 8 shows an exemplary angular rotational speed profile of the laundry drum during a spin cycle.

Fig. 9A-17 illustrate various motor speed/torque variations and OOB mass positions to mitigate laundry load imbalance in a laundry appliance.

Fig. 18 is a flowchart illustrating a method of reducing OOB laundry load in a laundry device.

Fig. 19 to 22 show various wash load distributions and associated target areas.

Fig. 23 illustrates a typical improvement of OOB state of redistributing laundry load quality in a drum by performing a speed drop.

Detailed Description

Various embodiments of laundry devices for assessing and mitigating unbalanced (OOB) wash loads are described below.

1. Imbalance interpretation

First, an explanation will be provided of unbalanced washing load in a laundry device (also referred to as a "washing machine" or "washer", which is used interchangeably).

Typically, the washing machine (laundry device) 1 operates in two different modes during its cycle:

a) A cleaning mode in which the laundry device drum 11 rotates relatively slowly to turn over and/or agitate the laundry load (i.e., laundry, such as clothes, linen, etc.) and wash liquor within the drum, thereby cleaning the wash load by mechanical action. In this mode, there is a relative movement between the washing load and the inner surface of the drum; and

b) A rotation mode (also referred to as a "rotation cycle") in which the drum 11 rotates at a relatively high speed ("rotation speed") to remove liquid from the wash load by centrifugal force (e.g., to remove foam after a cleaning phase, to saturate the wash load during a rinsing phase, or to remove as much water as possible during a spinning phase). In this mode, the drum 11 reaches a satellite speed in which the centrifugal force is sufficient to overcome the gravitational force acting on the laundry load, so as to cause the laundry load to adhere to the inner surface of the drum 11 and rotate therewith (also known as a "smoothed" or "satellite" condition of the laundry load, see for example fig. 1B). It should be understood that "rotational speed" and "speed" herein relate to angular speed, and any reference to rotational speed, angular speed (or angular rate), rotational speed is used interchangeably to describe the rotational (turning) rate.

Referring to fig. 1A, 1B and 1C, when the laundry apparatus is operated in a rotation mode, an unbalanced (OOB) state occurs when the mass of the laundry load 2 is unevenly distributed around the rotation center of the drum 11. Note that fig. 1A to 1C schematically show non-limiting examples of actual distribution of laundry that may cause OOB. Rotating the drum 11 in an unbalanced condition may cause undesirable vibrations and resonances that result in noisy operation and potential damage to the drive and suspension systems of the machine. In some cases, the amplitude of the vibration may cause the drum 11 to strike the cabinet 12 of the washing machine.

To address or improve (more generally, "mitigate") the OOB conditions, the wash load may be more evenly redistributed around the center of rotation. For example:

fig. 1A shows an OOB state in which the mass of the wash load 2 is unevenly distributed around the circumference of the drum, but concentrated in one circumferential region of the drum. In this case, by moving some of the load away from the mass concentration area, the OOB state can be resolved or improved (together "eased") such that a more uniform wash layer is smeared out around the circumference of the drum;

fig. 1B shows an OOB state, in which the washing load mass 2 is not at all at one circumferential region of the drum. In this case, the OOB status may be resolved or improved by transferring some of the wash load to an area without quality;

fig. 1C shows an OOB state in which a single wash load item (e.g., a sheet or towel) is rolled up or gathered at a specific circumferential region of the drum 11. In this case, the OOB condition may be resolved or improved by moving the articles in a manner that causes them to spread, unwind or redistribute, and to be more evenly placed around the circumference of the drum.

In this embodiment, each OOB state shown in fig. 1A, 1B, and 1C may be illustrated/modeled as a point mass (OOB mass) 4 that acts through the center of mass of the unbalanced wash load, as shown in fig. 2A, 2B. When the drum rotates at a speed ω, centrifugal force F presses the masses radially outward. The higher the velocity ω, the greater the centrifugal force.

The OOB mass 4 is a notional mass (a position that may change over time) with a notional position, which is not the mass of the actual wash load 2 or its distribution, but rather a model/illustration of such actual mass 2 is provided. The rotation of the unbalanced washing load (indicated, for example, by the rotation of the OOB mass) causes an oscillating excitation of the drum (which hangs on a spring inside the laundry device) and thus an oscillating movement of the drum in a plane orthogonal to the rotation axis, here indicated by the arrows X and Y. The goal of resolving or improving (mitigating) the OOB state is at least in part to reduce the magnitude of this motion.

2. Washing device with OOB function

An exemplary apparatus for performing the method of the present embodiment is described with reference to fig. 3 to 5.

In summary, as shown in fig. 3, the laundry device 1 (in this case a horizontal shaft/front loading laundry device) has a motor 10, an outer drum 5 and a horizontal shaft inner drum 11 suspended (e.g. by springs 18) in an outer cabinet ("housing") 12, a weight sensor 14 and a motor sensor 15. The motor drives the drum in rotation and oscillates in rotation in the axial direction along the x-axis (see inserted in fig. 1). The output signal of the weight sensor 14 can be used to derive information indicative of the load size (mass). The laundry device also has an accelerometer 17 ("motion sensor") for detecting the motion of the drum 5, 11. The output signals of the motor sensor 15 (which may be an angular position sensor, or an angular velocity sensor), the weight sensor 14, and/or the accelerometer 17 may be used to derive information representing the movement of the drum 11 due to the OOB state. Note that the weight sensor 14 and the motor sensor 15 are optional, and alternatively, the load mass and motor speed may be determined "sensorless" via motor current/torque (e.g., output from a motor controller). According to the present method, the controller 16 controls the motor 10 to drive the drum 11.

Referring to fig. 3, the controller is connected to the motor 10 and/or motor sensor 15, accelerometer (or other motion sensor) 17, weight sensor 14, and any other sensor (e.g., water pressure sensor) of the laundry device. (note that these may also be provided in the exemplary embodiment of fig. 4). The controller 16 may provide a signal to drive the motor 10, which motor 10 in turn drives the rotation of the inner drum 11. The controller 16 is programmed to receive input data, determine OOB output parameters (OOB evaluation-described later) to characterize the OOB state, and then take appropriate actions to resolve or improve (mitigate) the OOB state (OOB mitigation).

Accelerometer 17 (if used), weight sensor 14 (if used), motor speed 15 (if used), and/or position sensor (if used), as well as any other components that provide information that may characterize the OOB state, are referred to as "OOB sensors. In addition to OOB evaluation and OOB mitigation, OOB sensors may also be used for other evaluation and control. As previously described, the motor 10 itself may act as an OOB sensor so that data from the motor (e.g., current, torque, position, speed, and temperature) may be processed to provide information that may be used alone or in combination with other information to enable characterization of the OOB state.

For example, the controller 16 may be programmed to take one or more of the following actions to resolve or improve (mitigate) the OOB quality 4, thereby resolving or improving (mitigate) the OOB state:

stop or slow the drum rotation;

increasing the drum rotation speed;

maintaining the current rotation speed of the drum;

reversing the direction of rotation of the drum, or oscillating the drum in alternating directions of rotation;

performing a drop in the rotation speed of the drum, which causes at least some of the washing load to be redistributed and satellite at the new position; and

the rotation speed profile is changed during the revolution of the drum rotation, so that there is, for example, an extension or a shortening of the period of time during which the drum rotates at a specific speed.

Preferably, these actions mitigate (e.g., eliminate or at least reduce) the OOB state/mass 4 within one revolution of the drum or within a small number of revolutions. Taking action may reassign the actual wash load mass 4, which may alleviate the OOB mass 4, thereby alleviating the OOB status. The reference to reassignment implies some movement of the actual wash load. This may occur, for example, due to slowing down the rotation, such that redistribution occurs due to gravity, friction, centrifugation, elastic forces, or other forces.

Referring to fig. 4, a washing apparatus 1 of a horizontal axis (also referred to as "front loading") type is shown as one example of a washing apparatus of a general washing apparatus according to fig. 2A, 2B. The front loader comprises an outer casing 12, the outer casing 12 having a front door 3 to allow access to a perforated rotatable inner drum 11, the inner drum 11 being for holding a laundry load such as erases for washing and being mounted within the outer casing for rotation about a horizontal axis (x-axis). A generally cylindrical fixed (non-rotating) outer drum 5 for containing washing liquid is mounted (suspended on springs 18) within the cabinet 12 around the rotating inner drum 11. A motor 10 is attached to the rear of the outer drum 5 to directly drive the inner drum 11 to rotate about a horizontal axis relative to the outer drum 5.

Fig. 5 shows a cross section of the inner and outer drum 11 and 5 and the motor 10 of the laundry device of fig. 4. In fig. 5, the outer casing 2 is not shown. The stator 6 of the axial flux motor 7 is fixedly attached to the end of the (non-rotating) outer drum 5, for example by being mounted to a carrier housing structure 21, which carrier housing structure 21 is held in the end wall 5a of the outer drum 5. The rotor 8 outside the outer drum 5 is rotatably fixed to the outer end of a rotor shaft 9, the rotor shaft 9 extending through a passage in the end of the outer drum 5 and engaging at its other end with a rotating inner drum 11. The rotor shaft 9 is mounted by at least one or more bearings 20, such as roller bearings carried by the carrier housing member 16.

It should be understood that fig. 4 and 5 are examples only, and that the method of the present embodiment can alternatively be performed in different laundry devices, such as laundry devices that are directly driven by some other type of motor (e.g., radial flux motor), or in machines that are not directly driven, but are driven by a belt and/or gearbox. The laundry device may be a horizontal axis machine, or a tilt axis machine (e.g., a machine in which the drum 11 is tilted at a 45 degree angle).

3. OOB method for washing machine

A method, comprising:

OOB assessment-i.e., determining OOB parameters (e.g., OOB status and/or OOB quality), then

OOB mitigation-i.e., OOB status/OOB quality mitigation and/or wash load redistribution.

The method will be first outlined and then described with examples. These summaries and examples are collectively referred to as "OOB methods".

3.1OOB evaluation/alleviation-overview

The method implemented by the controller may generally follow the steps shown in fig. 18.

In step 60, the controller 16 rotates the drum 11 by operating the motor 10 to start a rotation cycle of the washing machine 1. The controller 16 is configured to drive rotation of the drum according to a (e.g. predetermined) angular velocity profile during a rotation cycle. For example, as shown in fig. 8, the controller may operate the drum rotation according to a spin cycle speed profile. This shows the change in rotational speed over time during the rotation cycle 80. During the rotation period, the rotation speed has various phases including a ramp portion where the rotation speed increases and a plateau portion where the rotation speed is maintained constant for a period of time. For example, as shown in fig. 8, the rotational speed profile includes three stages 81, 82, 83, 84, the first stage including a ramp portion 81A and a land portion 81B, the second stage including a ramp portion 82A and a land portion 82B, the third stage including a ramp portion 83A and a land portion 83B, and the third stage including a ramp portion 84A and a land portion 84B. This is by way of example only, and other rotational speed profiles may be used.

The OOB method of the present embodiment is implemented at one or more OOB decision points, typically at one of (but not limited to) a speed platform, where the OOB state is substantially "stable". In this example, the method is performed at a first speed platform 81B, which is typically about 93RPM, but this is not limiting and is merely exemplary. Alternatively, the method may be performed at a subsequent speed stage (e.g., 82B, 83B, 84B) or higher rotational speed. For example, the rotational speed may be up to 500RPM (e.g., 100, 200, 300, 400, or 500 RPM). At step 61, the rotational speed is increased at least by the first resonant frequency of the suspension assembly, up to the first speed platform 81B, through which point the load is centrifuged 43, thereby causing the load to rest against the inner circumference 41 of the drum 11 (due to centrifugal force). This may be referred to as component "satellites".

Fig. 8 shows the rotational speed of the drum 11 in a conventional rotation cycle 80. The inner drum 11 is driven through the speed of resonance of the suspension assembly (i.e., drum, wash load and motor on springs supported within the cabinet) and then at a constant speed for a period of time, e.g., 81B, 82B, 83B, 84B. During a first period of time of the constant speed or speed platform 81B, the wash load satellites 41. That is, the load is smoothed relatively uniformly in thickness and distribution to the inner surface of the drum 11 by the centrifugal force. However, as explained with respect to fig. 1A to 1C, some loads may not be evenly distributed about the rotation axis, and this may cause an OOB state of the drum 11, which may be represented by a conceptual OOB mass 4 (as described above and with respect to fig. 2A), and the motion thereof will be described below.

At step 62, at an appropriate point in the spin cycle 80 (e.g., at the first platform 81B), the controller 16 determines an imbalance (OOB) parameter (e.g., OOB quality 4 and/or OOB status). This may be information indicating the position (e.g. angular position) and/or size of the OOB mass 4, and may additionally include information about the distributed mass of the suspension assembly, and/or information about where the load mass is located along the axial direction of the drum. The OOB parameter may be determined in any method known in the art for detecting and characterizing unbalanced loads in a laundry device.

At step 63, after determining the OOB parameters, the controller 16 determines whether the OOB parameters (e.g., OOB status and/or OOB quality 4) are acceptable or whether reassignment is therefore required. Also, various methods are known in the art for determining whether an OOB parameter is acceptable or whether the parameter exceeds a certain threshold above which vibration or movement of the drum is excessive or predicted to be excessive at higher speeds. In general, if the OOB parameter is above the threshold or on the wrong side of the threshold, determining an OOB state; if the OOB parameter is below or on the correct side of the threshold, the OOB state is resolved. For example, such an approach generally considers whether the magnitude of the OOB mass 4 exceeds a certain threshold, and the threshold to be exceeded may vary depending on where the load mass is concentrated in the axial direction (concentrating the load mass near the front of the drum (away from the bearing) is considered to be a greater problem than concentrating the load mass near the rear of the drum and near the bearing). If the OOB parameter is acceptable (e.g., OOB quality is below a threshold), at step 64, the spin cycle continues in a manner generally known to those skilled in the art. For example, the rotational speed may proceed to the next speed platform, where the evaluation of the OOB parameters is repeated in the manner described above. However, if the OOB parameters are not acceptable, further action is taken to improve or resolve (i.e., mitigate) the OOB state prior to increasing the drum speed.

The controller 16 then determines the angular position of the OOB quality at step 65.

The OOB mass 4 and its movement are further described with reference to fig. 6A-6D. These figures show the 0, 90, 180 and 270 degree angular positions of the OOB mass 4 during one revolution of the inner drum 11 in the counterclockwise direction a (wherein the reference of the 0 degree angular position is set to the lowest point of the OOB mass at which it rotates). In this reference system, the rotation bottom B is 0 degrees, 90 degrees is the right hand side R, the rotation top T is 180 degrees, and 270 degrees is the left hand side L, but note that the angular position is a conceptual reference system for descriptive purposes and not limiting. Any suitable frame of reference may be used.

In step 65, to perform the method of the present embodiment, the controller 16 determines the angular position of the OOB mass 4 as the drum rotates. For example:

a) One or more accelerometers (or other motion sensors) 17 attached to the inner and/or outer drum 11 may be used to measure the magnitude of acceleration in the X and Y directions (as shown in fig. 2A, 2B) from which the angular position of the OOB mass 4 may be derived; and/or

b) The angular position of the OOB mass 4 may be determined by monitoring the cyclical variation of the motor torque (or some parameter indicative of the motor torque, such as current, amperage, or motor angular speed or acceleration) that occurs in response to the torque exerted by the OOB mass on the drum. As shown in fig. 7, when the OOB mass is at the 90 degree angular position, the motor torque reaches a maximum value, and thus, a negative torque is applied with respect to the counterclockwise movement of the drum under the force of gravity. Conversely, when the OOB mass is at the 270 degree angular position, the motor torque reaches a minimum, and therefore, under the force of gravity, a positive torque is applied relative to the counterclockwise motion of the drum. The time for the OOB mass to reach the 180 degree angular position (i.e., the highest point during rotation) may be estimated to occur approximately halfway between the occurrence of maximum and minimum motor torques.

Motor speed and/or position sensor 15 may be used to determine the angular velocity of motor 10. For example, a hall effect sensor or encoder may be used. Alternatively, however, data from the motor, such as current, (or some other type of sensorless control method) may be used to estimate the position and/or speed (i.e., angular position and/or angular speed) of the motor.

In at least some embodiments, to implement the method of the present embodiments, the apparatus provides a method and/or apparatus for determining the quality of the wash load 2. The weight sensor 14 may be used to determine the mass of the wash load. For example, the weight sensor 14 may be located in a foot 30 of the washing machine (see FIG. 4), or on the suspension 18 (see FIG. 3), to measure the spring extension under the load weight. Alternatively, however, the data from the motor may be used to estimate the mass of the washing load 2, for example based on the torque required to accelerate the rotating inner drum from a first speed to a second speed, or on the time the motor spends on coasting after briefly rotating the load in a dry state.

Thus, based on the foregoing, the controller 16 monitors the rotating drum 11 and determines and/or receives OOB parameters that indicate the presence/absence and/or severity of OOB status/quality of the drum 11. As part of the above, the controller 16 may also determine and/or receive information representative of the approximate position of the OOB mass 4 (i.e., the angular position relative to a reference point, such as the rotational bottom/imaginary 0 degree angular position in fig. 6A-6D) as the OOB mass 4 and the drum 11 rotate.

It should be noted that although the present description refers to the angular position of the OOB mass 4, this OOB mass is an imaginary point mass 4 on the circumference of the drum, which is a model/representation of the resultant force due to the real OOB state in the drum (i.e. due to the mass of the real wash load 2). Thus, there may be no actual mass at the angular position of the OOB mass 4, e.g., there may be two actual masses 2 near the OOB mass 4, one at a positive angular position relative to the OOB mass and one at a negative angular position relative to the OOB mass, as shown in fig. 6E. The method of the present invention is based on the assumption that at least some of the mass (actual mass) of the actual wash load 2 may be in the vicinity of the OOB mass 4, and thus that taking measures to redistribute items at or near the location of the OOB mass 4 has a higher likelihood of improving or resolving the OOB state than can be achieved by randomly redistributing items.

In general, in order to attempt to improve or resolve the OOB status, and attempt to redistribute the actual wash load (actual mass) 2, the OOB mass 4 is reduced or eliminated. At step 66, the method and apparatus of the present disclosure determine an appropriate change in rotational speed and vary the rotational speed (also referred to as "angular speed") of the washing machine drum 11 at a target angular position of the drum rotation cycle. The change in rotational speed is less than/within one revolution of the drum. Changing the rotational speed of the washing machine drum may redistribute the actual load such that the conceptual OOB mass 4 is reduced or eliminated. If the OOB quality 4 decreases/disappears, it can be inferred that the actual wash load 2 has been at least partially redistributed, which results in an improvement or resolution of the OOB status. At a general level, the method is based on the following: by redistributing the actual wash load mass 4 modeled by the OOB mass 4, there is a higher percentage opportunity to improve or resolve the OOB state.

At step 66, the controller determines an appropriate rotational speed change to mitigate the OOB based on the information received:

a) The received information indicates the size of the OOB quality, and/or

B) The information received indicates the radius R of the cylinder, and/or

C) The received information indicates the angular velocity of the drum/OOB mass, and/or

D) The received information indicates an angular position of the OOB quality, and/or

E) The received information indicates the size (volume and/or mass) of the wash load, and/or

F) The received information indicates the satellite velocity.

At step 66, the controller 16 controls the rotational speed of the washing machine drum 11 by controlling the rotational speed of the motor 10 based on the determined rotational speed, wherein the determined rotational speed is based on the controller 16 determining and/or receiving the input OOB status/quality 4.

For example, the rotational speed variation may be a speed profile ("lightening speed profile") that includes a speed that varies with the time/angular position of the drum 11. Generally, the velocity profile may be as follows. During rotation of the inner drum 11, with the angular position of the OOB mass (when rotating with the drum): a) approaching a target angular position, b) being near the target angular position, c) being at the target angular position, and/or d) leaving the target angular position 40 of the washing machine 10), the angular speed of the washing machine drum 11 decreases. Preferably, the angular velocity of the drum is reduced by less than one revolution before the drum returns to normal.

Preferably, the target angular position is at a point more than half way (e.g. above the point R/90 angular position shown in fig. 6 b), at which the effect of gravity may be to bring the mass 2 radially inwards/away from the drum, and/or to drop the laundry load to the lower part of the drum. The centrifugal force 43, which is reduced in speed to OOB mass 4, is no longer sufficient to counteract gravity G to keep the mass satellite during the upper half of rotation. Thus, OOB mass may drop under gravity G when deceleration occurs. Then, as the angular position of the OOB mass 4 moves away from the location 40, or out of the vicinity of the location (e.g., a target area such as a wedge), the angular velocity increases and/or returns to normal, causing the mass to satellite again at the inner surface of the drum for subsequent rotation.

Therefore, when the OOB mass 4 reaches the target angular position (or when the OOB mass approaches the target angular position), the drum 11 decelerates to the second angular velocity, and accelerates back again to its first angular velocity or increased angular velocity after leaving the target angular position, resulting in performing "speed drop".

The deceleration of the drum reduces the centrifugal force 43 on the laundry in the drum, allowing at least some of the laundry load mass 4 in the upper half of the drum 11 to drop under the force of gravity G and fall to another peripheral location of the drum. It is contemplated that when mass 2 falls and/or falls into a location where there was a localized area of previously low garment mass, mass 2 may spread out (e.g., as shown in fig. 1B), thereby causing the mass of the garment to be more evenly redistributed about the center of rotation. When the drum returns to its first speed or increased speed, the falling mass will satellite in a new position. This will preferably take place within one revolution of the drum rotation and the drum continues to rotate at a high speed after the speed reduction has been performed.

Note that although the angular position of the OOB mass 4 is used as a reference point for changing the velocity, it may actually be the target area 70, such as described later with reference to fig. 20.

In some embodiments, the speed reduction is performed such that the deceleration rate is achieved in a faster/shorter period of time than the subsequent acceleration rate returns to the satellite speed. For example, a rotating drum rotating at about 93RPM may be decelerated at a rate of about 1000 RPM/second and then subsequently accelerated at a rate of about 50RPM while returning to satellite speed.

In this regard, it has been found advantageous to use the mass of the laundry load/drum to help perform motor speed reduction so that deceleration and acceleration during speed reduction can be synchronized with the rise and fall of OOB mass during rotation thereof. For example, referring to fig. 6B and 7, it is advantageous to slow down the OOB mass 4 when passing through the 90 degree position, at which point the negative torque applied by the OOB mass 4 is greatest and can assist in rapid deceleration of the drum speed. Conversely, when the OOB mass drops from the top of the rotation (i.e., 180 degree position) to the bottom (i.e., 0 degree position), the torque exerted by the OOB mass may be used to assist in accelerating the drum speed back to satellite speed within a single rotation of the drum.

As an example (not limited thereto), during the rotation cycle, the washing machine drum 11 rotates at a first angular speed S1, at which first angular speed S1 the washing load is completely satellite. Then, during a single rotation cycle, when the angular position of the OOB mass (while rotating with the drum) reaches the target angular position (see detailed description later, but as an example this may be 90 degrees in fig. 6B), the drum decelerates to the second angular speed S2 and accelerates back again to its first angular speed (i.e., performs a "speed dip"). Generally, when the OOB mass reaches, approaches, or leaves the top 180 degree angular position (e.g., as shown in fig. 6C), the drum decelerates to speed S2. When the drum returns to its angular speed S1, the falling mass will satellite in the new position. This will preferably be done within one revolution of the drum. More details about the example described in fig. 9A, 9B will be provided later.

Once the controller has controlled the motor to the speed profile, step 62, the controller 16 again measures the OOB mass 4/OOB status, and if not acceptable, again determines and implements a rotational speed change, step 63; or if acceptable at step 63, continue with the normal rotation profile at step 64. For example, after or in parallel with performing "speed-down", the imbalance parameters will be monitored and again determined at step 62. If the speed drop is effective in redistributing the actual load mass 2 such that the OOB status is resolved or improved to a level where OOB parameters (e.g., OOB mass 2) are acceptable, rotation may continue according to the normal profile 80, as in steps 63, 64. However, if the OOB parameters are not acceptable (indicating that there is still a problematic OOB state), such as step 63, the mitigating speed profile may again be applied to perform a further speed reduction or a series of speed reductions. Of course, due to the redistribution of actual load masses 2, the OOB masses 4 may have changed in location, size, and other parameters, and thus the mitigation speed profile may also change, such as initial timing, speed change, and/or target location/area for the new OOB mass 2. However, in some embodiments, a mitigation speed profile (e.g., target position/zone and corresponding speed change) is set, and the same mitigation speed profile is repeatedly applied, changing the timing of the signal only in accordance with the angular position of OOB mass 2.

More generally, if desired, the change in rotational speed of the washing machine at the target angular position of the OOB mass 4 will be repeated until the controller 16 has determined that the OOB state/mass 4 has been sufficiently improved or resolved (e.g., the OOB parameter is less than the threshold or on the correct side of the threshold), at which point the rotation of the drum 11 will return to the predetermined angular speed profile of the spin cycle. For example, referring to fig. 8 and 18, the method may also be performed multiple times, e.g., once per rotational speed platform 81B, 82B, 83B. Even when the OOB quality/state is reduced at a first rotational speed stage (e.g., 81B), a new OOB quality/state may occur as the rotational speed ramps up to a subsequent stage (e.g., 82). Thus, the method of FIG. 18 may be performed at different times during the rotation period.

3.2 example of rotational speed variation

With reference to fig. 9A, 9B, an example of determining and implementing a mitigation speed profile will be described. Fig. 9A shows a profile of motor torque over time, which varies at time T1. Fig. 9B shows an angular velocity versus time (alleviation of the velocity profile) profile. As an example, this will refer to two rotational speeds S1, S2 during a rotation period. These are merely exemplary and should not be limiting. A variety of speeds, or tilting/varying speeds, may be used. In this case, S1, S2 refer to target speeds, and in order to reach these speeds, the motor will pass through the speed range en route.

In this case, for example, OOB evaluation may be initially performed at the first rotational speed platform 81B in fig. 8. Referring to fig. 18, step 66 and fig. 9B, the controller 16 determines a reduced speed profile that varies the angular speed of the motor (i.e., the motor speed drops) between the rotational speed S1 and the lower speed S2, and controls the motor accordingly by a control signal.

a) S1 generally coincides with the angular velocity at the speed plateau (e.g., 81 of fig. 8) of the predetermined speed profile of the wash cycle. Considering that the radius R of the drum, S1 is higher than the speed required for satellite washing loads. Various methods for determining satellite velocity are known in the art (e.g., where f=mmw2r, solve for W, where Mg > mw2r, and W < sqrt (g/r).

b) The deceleration of S2 should achieve a sufficient reduction in centrifugal force such that at least some of the wash load mass falls under gravity G and falls to another circumferential position of the drum. Therefore, S2 should be lower than the satellite speed.

In some embodiments, S2 may be obtained empirically, noting that the time taken to achieve redistribution may be reduced by minimizing the difference between S1 and S2.

The controller 16 also determines a mitigation speed profile that will slow the rotation of the drum 11 to a speed S2 below the satellite speed at a desired time T1 (corresponding to a certain angular position of the OOB mass 4), as step 66, with the result that the real mass located within the "target area" of the drum may drop under gravity G and redistribute at alternative circumferential positions.

The reduced speed profile causes the motor to change from standard, the normal motor speed being the speed at which the drum is rotated at a constant rotational speed. The mitigation speed profile of this example has one or more of the following:

a) Start time T1 and/or stop time, and/or duration of motor speed reduction, and/or target time T1 to reach speed S2, and/or duration of holding speed S2;

b) Slope or rate of acceleration and/or deceleration; and

c) The magnitude of the rotation speed S1, and/or the target reduction speed S2, and/or the magnitude of the motor speed reduction is determined.

As shown in fig. 9A and 9B, the control signal decelerates the drum to S2 at a time T1/180 degrees, where the time T1/180 degrees approximately coincides with the OOB mass (or where the target area is used) reaching, approaching or exiting an angular position of 180 degrees (e.g., as shown in fig. 6C, where the reference of the 0 degree angular position is set to the OOB mass at its lowest point during rotation). Various methods known in the art for determining the angular position of OOB quality are discussed above in connection with fig. 6A-7.

As an example, referring to fig. 6A-7, motor data may be used to determine when peak motor torque (Tmax) occurs, and this may be understood to reflect the time the OOB mass reaches a 90 degree angular position. The time it takes for the OOB mass to complete a further quarter turn to the 180 degree angular position (T1) can then be estimated from the known angular speed of the drum (S1). Thus, the control signal must drive the drum to speed S2 approximately T1 seconds after Tmax. Because the deceleration is not instantaneous, the controller may initiate the deceleration at a time Ti prior to T1. In some embodiments, the controller 16 may be configured to slow the drum when the OOB mass reaches a certain angular position slightly before or after reaching the 180 degree angular position, in which case T1 may decrease or increase accordingly.

It will be appreciated that the motor may alternatively be driven to vary the rotational speed over a specific time interval, additionally or alternatively the motor may be driven to vary the rotational speed in dependence on the angular position of the rotor of the motor itself (which is directly coupled to the washing machine drum). In this case, the control signal may include, for example, a start and/or stop angular position, and/or a range of angular positions over which the rotational speed of the rotor varies, and/or a target angular position of the arrival speed S2 of the rotor, and/or a range of angular positions of the motor during which the motor angular speed remains at S2. It will be appreciated by those skilled in the art that determining the change angular velocity based on time or based on the angular position (of the drum) is interchangeable and is merely a matter of the control/sensor means used. The examples herein are not limiting and any control means that achieves a speed change at the appropriate location/range of drum rotation may be used.

In this embodiment, the controller 16 determines the angular position of the OOB quality, step 65.

On a general level, the OOB method proceeds based on the following: by redistributing the actual wash load mass 2 at or near the OOB mass 4, there is a higher percentage of opportunities to improve or resolve the OOB status than can be achieved by randomly redistributing the actual load mass or by redistributing the actual load mass away from the OOB mass. That is, by decelerating the drum to S2 at approximately the same time that the OOB mass reaches the 180 degree angular position, a conceptual "target zone" 70 (see fig. 11, 12 or more generally fig. 20) is created around the OOB mass such that the actual wash load mass located within the target zone can be redistributed by the change in drum speed. At its broadest level, this approach would work if the "target area" extended 90 degrees in either direction from the angular position of the OOB mass, as shown for example by the shaded hemispherical area in fig. 11.

In this embodiment, the motor speed control signal profile is defined such that it controls the motor drum 11 such that a reduction in rotational speed occurs over a range of angular drum rotational positions such that the radially outward centrifugal force acting on the actual mass 2 (at the radial and/or angular position of the OOB mass 4) is less than the radially inward/gravitational force G acting on the actual mass 2 such that the actual mass 2 will disengage from the position where it is located and fall. The actual mass may drop and/or flip directly so that the wash load may be redistributed and the OOB mass removed.

Referring to fig. 20, the reduction in drum speed may occur during the angular span 71, creating an imaginary wedge-shaped region (target region 70) in which any actual wash load mass located therein will experience reduced centrifugal force and may experience redistribution. Typically, the speed profile will be such that a speed reduction occurs when the OOB mass 2 is near, and/or at the top 40 of the washing machine. However, this is not complete. In fact, the reduction may occur at any point between the halfway horizontal points 73A, 73B of angular rotation, i.e. at any point within the range of 180 ° of angular rotation, such as angle A, B, resulting in a target area span C (=180-a-B). The target region 70 will also have a radial extent R determined by the rotational speed profile in the manner described above.

Thus, in general, the motor speed control signal can be varied to vary the speed profile of the rotating drum to produce a target zone 70 defined by an angular span C and/or an angular start position B and a stop position a and/or a radial span R, where the radial span R is a radial extent from the center of the target zone.

It has been found that the angular range of the target area can be changed by the profile of the operating control signal as follows:

it will be appreciated that if the drop in motor speed is performed very quickly, there will be only a momentary decrease in centrifugal force as the OOB mass 4 passes over the top of the drum 11, and only the actual wash mass located near the OOB mass (e.g., mass located in the target area (shaded area) in fig. 13) will drop and redistribute. Thus, the angular range of the target region can be reduced by increasing the deceleration and acceleration rates as the control signal parameters. Fig. 12 shows a control signal in which the rate of deceleration and acceleration has been increased (relative to the control signal shown in fig. 10 above). Fig. 13 illustrates the resulting reduction in the angular extent of the target area (as compared to the target area previously illustrated in fig. 11) such that the target area extends only 40 degrees on either side of the OOB mass. That is, the acceleration and deceleration parameters of the control signal may be selected such that only the actual wash mass in the target area 40 degrees on either side of the OOB mass may be redistributed by the change in drum speed, while the mass outside the target area remains satellites.

Similarly, it was found that extending the amount of time spent at speed S2 can increase the angular range of the target area. However, it may take a finite time at speed S2, since the motor speed must return to S1 (or at least to the speed at which the load satellites) within the time it takes for the drum to complete one revolution, and preferably to S1 (or at least to above the satellite speed) within the time it takes for the drum to complete more than half a revolution of T1.

This is more generally shown in fig. 21, where a faster tilt (see left hand side) has a smaller angular target range and a slower tilt (see right hand side) has a larger angular target range.

One reason that it may be desirable to change the angular extent of the target area on either side of the OOB mass is that, as explained with respect to fig. 6E, there is an opportunity that virtually no real load mass 2 is located at the angular position of the OOB mass 4. In this case, attempting to reallocate quality within the vicinity of OOB quality 4 may not be successful (i.e., there is no actual quality 2 reallocation) and the OOB status may not be resolved or improved. In this case, it is desirable to repeat the "speed drop" with an increasing angular extent of the target area (right hand side of fig. 21) in the hope that the actual load mass that was not redistributed in the previous attempt can now be captured in the target area and successfully redistributed.

It has further been found that the radial extent of the target area can be changed by the profile of the operating control signal as follows:

theoretically, the angular velocity required to satellite the OOB quality depends on the radius R of the drum (as shown in fig. 15), and the value of S2 can be calculated accordingly. Alternatively, the value of S2 may be obtained empirically by satellite-sizing the article at the periphery of the drum.

However, if there is a full load of laundry in the drum 11, not all the real masses 2 will be located at the radius R of the drum. In this case, the OOB state may be improved or solved by redistributing the real mass located at the smaller radius R2 of the drum (e.g., as shown in fig. 17). In order to redistribute the load mass at this smaller radius R2, it is not necessary to slow down the drum as required to redistribute the mass at radius R.

Fig. 16 shows a control signal in which the speed S2 has been increased (relative to the control signal shown in fig. 4 above). Fig. 17 shows the resulting reduction in the radial extent of the target area (compared to the target area shown in fig. 15 above) such that the target area extends to a radius R2, which radius R2 is smaller than the radius R at which the OOB mass is located. That is, the S2 parameter of the control signal may be selected such that only the actual cleaning mass located in a target area smaller than the radius of the OOB may be redistributed by the variation of the drum speed, while the mass located outside the radial extent of the target area remains satellites.

In one example, the mass of the wash load may be measured (by the method previously described), and if the measured load mass exceeds a certain threshold designated to indicate "full" or large load, a smaller radius R2 (as compared to the maximum value of R) may be allocated. A smaller radial value R2 may be assigned because a larger mass/full load may have a load mass located at a smaller radius R2 (e.g., as shown in fig. 17) than a smaller mass/half load, which is more likely to have a load mass located near the periphery R of the drum (e.g., as shown in fig. 1B).

Thus, in the manner described above, a control signal/speed profile may be calculated that will slow the drum to a speed S2 below the satellite speed to achieve a redistribution of the actual mass within a defined target area, which is defined in terms of angular position relative to the OOB mass and the angular and radial extent of the drum radius R.

Fig. 22 illustrates some general control signal parameters that result in a reduced speed profile that results in various target areas 70 to redistribute OOBs that fall within the target areas.

1.3.2 exemplary embodiment

An example of how to determine an appropriate control signal profile can be given with respect to a washing machine having a wash load capacity of about 8kg and a drum radius of about 0.262m, rotating at a rotational speed S1 of about 93RPM (9.7 rad/sec) on a first speed plateau of a wash cycle rotational speed profile. Before starting the spin cycle, the mass of the wash load has been determined to be about 6kg:

a) The satellite speed of the actual wash load mass just within the radial periphery of the drum can be calculated as sqrt (G)/. 262) =6.11 rad/sec or 58RPM, with the speed S2 set to about 58RPM accordingly.

b) Since the 6kg wash load is 3/4 of the machine wash capacity, it can be determined that the load is large. In case of large loads, it is not desirable to target the actual wash load mass just within the radial periphery of the drum, but rather the actual wash load mass at a smaller radial distance R2, for the purpose of redistribution. Thus, the speed S2 is modified (i.e., slightly increased) to reduce the radial extent of the target area, and S2 becomes 6.3rad/sec or about 60RPM.

c) The time ttorque_max, which may be the angular position at which the OOB mass reaches 90 degrees, is determined from motor data indicative of peak torque during each revolution. The time required for the drum to re-rotate one quarter turn at 93RPM may be calculated as 0.166 seconds, which is approximately the time required for the OOB mass to reach the 180 degree angular position. The controller determines the speed profile such that the drum decelerates to S2 at time T1, approximately 0.166 seconds after time t_torquemax.

d) The control signal may be activated at a time Ti just prior to T1, for example, the time Ti may be about 0.15 seconds after ttorque_max. In order to reduce the angular velocity from S1 at time Ti to S2 at time T1 as necessary, a deceleration rate is determined, and a substantially equal acceleration rate may be determined to increase the angular velocity back to S1. Because the rate of deceleration and acceleration is large, only the true load mass that is located near the OOB mass (i.e., within 40 degrees of either side of the angular position of the OOB mass) is captured within the "target area" for redistribution. Preferably, the deceleration and re-acceleration is completed within Trequest_max of 0.33 seconds (which is the time it takes for the OOB mass to travel half a turn from an angular position of 90 degrees to 270 degrees at 93 RPM).

However, as previously described, deceleration of the drum to speed S2 may occur slightly before or after time T1, at which the OOB mass is estimated to reach its 180 degree angular position. It has been found experimentally that activating the control signal at a time T1 between 0.15 and 0.2 seconds after time ttorq _ max can result in an improved opportunity to resolve or improve OOB status by redistributing items located near OOB quality (as compared to randomly redistributing laundry loads).

Performing several speed drops in series may increase the chance that the OOB state is adequately resolved or improved by repeating the time of steps 62 and 63. Because steps 62 and 63 take some time to perform, it is desirable to minimize the number of times that must be performed during the reassignment process. For example, in some laundry devices, it has been found that using the above-described method for reassignment can acceptably improve or resolve OOB laundry loads in an average time of about 65 seconds.

Fig. 23 shows a typical improvement of OOB status for redistributing load quality in a drum by performing a speed drop. Here, the "BE" value on the vertical axis is related to drum energy due to the swing caused by the OOB load, and is an indication of the severity of the OOB state. As the number of speed decreases increases, the BE value decreases, indicating that the OOB status is improved by the redistribution of the actual load mass within the drum.

In some embodiments, after each execution of a speed down (steps 65 and 66), OOB parameters are monitored/determined and acceptability is assessed (i.e., steps 62 and 63 are repeated). However, in some embodiments, a series of speed drops may be performed (i.e., steps 65 and 66 are repeated several times over several different revolutions of the drum) before steps 62 and 63 are repeated. In the case of several speed drops performed in series, the angular speed of the drum may return each time to its original angular speed S1, or alternatively at least to a speed higher than the satellite speed, and this speed may be, for example, a slightly slower speed than S1.

Claims (28)

1. A method of reducing unbalanced laundry load in a washing machine having a horizontal axis drum, the method comprising the steps of:

Rotating the drum above a satellite speed (optionally a constant speed) of the laundry load; and

the drum speed is changed by sequentially decreasing the drum speed and then increasing the drum speed to below the satellites speed and then above the satellites speed within a single rotation of the drum, thereby selectively dropping the laundry load in the drum under the force of gravity.

2. The method of claim 1, wherein the drum speed decreases to a speed below the satellite speed at a faster rate than the drum speed subsequently increases to a speed above the satellite speed.

3. The method according to claim 1 or 2, further comprising the step of:

a position (optionally an angular position) of the unbalanced mass of the unbalanced laundry load is determined.

4. A method according to claim 3, wherein the step of varying the drum speed coincides with rotation of the drum below the satellite speed, wherein the unbalanced mass is located at, near or through a high point of its rotation about the horizontal axis of the drum.

5. The method according to claim 3 or 4, further comprising the step of:

determining a target region having an angular extent of angular position relative to the unbalanced mass, and optionally a radial extent relative to a radius of the drum; and

wherein the drum speed is changed by sequentially decreasing and then increasing the drum speed to be lower than the satellites and then higher than the satellites within a single rotation of the drum to selectively drop the laundry load located in the target area by gravity.

6. The method of claim 5, wherein the angular range of the target region is between about 0-90 degrees in position relative to the unbalanced mass in either direction; or alternatively between about 0-45 degrees, about 0-30 degrees, about 0-15 degrees, or about 0-5 degrees in either direction relative to the unbalanced mass.

7. A method according to claim 5 or claim 6, wherein the radial extent of the target region is between about 25% -100% of the radius of the drum; or alternatively between about 40% -100%, about 60% -100%, about 80% -100% or about 90% -100% of the radius of the drum.

8. The method of any of claims 2 to 7, wherein one or more selected from the following is used as an input from which the location of the unbalanced mass is determined:

a. motor torque, power, current, speed, or voltage; and/or

b. Time (relative to a reference time point); and/or

c. Drum speed, drum angular position, drum linear acceleration, and/or drum angular acceleration.

9. The method according to any of claims 2 to 8, wherein the location of the unbalanced mass is determined using:

a. sensor data, optionally selected from one or more data from an accelerometer or gyroscope; and/or

b. Motor data, optionally selected from one or more of motor torque, power, current, speed, or voltage.

10. The method of claim 9, wherein the location of the unbalanced mass is determined using only motor data.

11. A method according to any one of claims 1 to 10, wherein during the step of varying the drum speed by sequentially decreasing and then increasing the drum speed below the satellite speed and then above the satellite speed, a control signal is used to control the rotational speed of the drum, the control signal having a different profile than the previous normal and/or constant control signal profile, and optionally having a pulse profile.

12. The method of claim 11, wherein the control signal varies based on one or more selected from the group consisting of:

a. motor torque, power, current, speed, or voltage; and/or

b. Time (relative to a reference time point); and/or

c. Drum speed, drum angular position, drum linear acceleration, and/or drum angular acceleration; and/or

d. A mass of the laundry load; and/or

e. The size/diameter of the drum.

13. The method of claim 11 or 12, wherein the control signal comprises one or more selected from the group consisting of:

a. angular start position/angular span/angular stop position of rotation speed decrease and subsequent speed increase;

b. time to start and/or end the rotation speed decrease and subsequent speed increase (relative to the reference point in time);

c. a decrease in rotational speed followed by a slope or rate of increase in rotational speed; and/or

d. The decrease in rotational speed and the magnitude or amplitude of the subsequent increase in speed.

14. The method of any one of claims 11 to 13, wherein the control signal profile produces a rotational speed profile of a rotating drum that selectively drops a laundry load in the drum under gravity; and

Optionally, wherein the control signal profile generates a rotational speed profile of the rotating drum that selectively drops the laundry load in the target area under gravity.

15. A laundry appliance comprising:

a roller;

a motor for rotating the drum;

optionally one or more sensors; and

a controller receiving input from the motor and/or the sensor (if present) and controlling the motor to rotate the drum,

wherein the controller is configured to mitigate unbalanced wash loads according to the method of any one of claims 1 to 14.

16. A method of mitigating unbalanced wash load in a washing machine having a horizontal axis drum, the method comprising:

determining an indication of an angular position and optionally a radial position of OOB mass of a drum of the washing machine; and

the rotational speed of the drum is controlled such that when the drum and the OOB mass rotate, the rotational speed of the drum varies relative to a normal speed based on the OOB mass such that the outward radial force on the wash load is reduced below the inward radial force and/or gravity.

17. The method of claim 16, wherein the rotational speed of the drum varies by less than one revolution of the drum.

18. A method of mitigating unbalanced wash load in a washing machine having a horizontal axis drum, the method comprising:

determining an indication of OOB quality of a drum of the washing machine; and

the rotational speed of the drum is controlled such that when the drum and the OOB mass rotate, the rotational speed of the drum varies relative to a normal speed over one revolution of the drum based on the OOB mass such that the outward radial force on the wash load is reduced below the inward radial force and/or gravity.

19. The method of claim 18, wherein determining an indication of OOB quality comprises determining an angular position of the OOB quality.

20. The method of any of claims 16 to 19, wherein a rotational speed of the drum varies based on the OOB quality and/or an angular position of the wash load.

21. The method of claim 20, wherein the OOB quality and/or the angular position of the wash load is determined based on:

a time when the drum rotates; and/or

The angular position of the drum as it rotates.

22. The method of any of claims 16-21, wherein a rotational speed of the drum is further reduced based on a radial position of the OOB mass.

23. A method according to any one of claims 16 to 22, wherein the rotational speed of the drum is controlled using a control signal having a different profile to the normal control signal.

24. The method of claim 23, wherein the control signal is based on the following changes:

a time when the drum rotates; and/or

The angular position of the drum as it rotates.

25. A method according to claim 23 or 24, wherein the control signal for controlling the rotational speed of the drum comprises:

an angular start position/angular span/angular stop position at which the rotational speed decreases;

the slope of the control signal can determine the speed of the speed decrease and/or the radial extent of the target area; and

the amplitude of the control signal can determine how much the speed is reduced and/or the radial extent of the target area.

26. The method of any of claims 23 to 25, wherein the control signal profile produces a rotational speed profile of a rotating drum that produces a target zone that redistributes OOB mass and/or wash load in the target zone.

27. The method of claim 26, wherein the target area comprises an angular span and a radial extent.

28. A laundry appliance comprising:

a roller;

a motor for rotating the drum;

one or more sensors; and

a controller receiving input from the sensor and controlling the motor to rotate the drum,

wherein the controller is configured to mitigate unbalanced wash loads according to the method of any one of claims 16 to 27.

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