OUT OF BALANCE METHOD AND APPARATUS

FIELD OF THE INVENTION

The invention relates to a laundry machine (such as a washer, dryer or combination washer-dryer) and to methods for controlling the laundry machine.

BACKGROUND TO THE INVENTION

Typically, a laundry machine operates in two distinct modes during its cycle:

- a) A cleaning mode in which the laundry machine drum rotates relatively slowly to tumble or agitate the clothes and wash liquid inside the drum, such that the clothing is cleaned by mechanical action. In this mode there is relative movement between the clothing and the inner surface of the drum; and
- b) A spin mode in which the drum rotates at a relatively high speed to remove liquid from the clothing by centrifugal force (for example to remove suds after a cleaning phase, or to remove as much water as possible during a dehydrating phase). In this mode the drum reaches a speed where the centrifugal force causes the clothing to adhere to (also termed “plastered” or “satellised”) the inner surface of the drum and to rotate with it.

Out of balance (OOB) loading occurs when the laundry load satellises during a spin phase with the mass of the load unevenly distributed about the centre of rotation of the drum. Spinning the drum in the OOB condition can cause undesired vibrations and resonances that result in noisy operation of the machine and potential damage to its drive and suspension systems. In some cases, the vibration may be of such magnitude that the drum is caused to strike the cabinet of the washing machine.

The laundry machine may be programmed to detect whether the drum is OOB at various stages during the spin phase. If OOB loading is detected then the laundry machine may be programmed to stop the drum completely so that the mass of the laundry load can be shifted. Further, the time taken to complete the spin phase may be significantly increased with repeated stopping of the drum to correct the OOB loading.

It is therefore an object of the invention to provide an improved or at least alternative method and/or apparatus for assessing out of balance in a laundry machine.

SUMMARY OF INVENTION

In one aspect the present invention may be said to comprise a method of assessing out of balance in a laundry apparatus comprising, during operation of the apparatus: receiving output from one or more OOB sensors, determining from the OOB sensor output: a mass and/or rotating inertia, and a relative phase between a rotating assembly motion and non-rotating assembly motion, and generating OOB output indicative of balance of laundry in the drum.

Optionally the method further comprises determining speed from the OOB sensors.

Optionally the method further comprises determining an OOB condition from the OOB output.

Optionally the method further comprises operating the laundry apparatus to mitigate OOB laundry if it exists.

Optionally the relative phase is determined from input received from a gyroscope and motor and/or drum speed.

Optionally the laundry apparatus comprises: a non-rotating assembly suspended within an outer cabinet, and a rotating assembly within the non-rotating assembly, comprising a drum for laundry, wherein the rotating assembly can be rotated relative to the non-rotating assembly by a motor.

Optionally the non-rotating assembly has a gyroscope.

Optionally the method comprises: further determining from the OOB sensor output: a non-rotating assembly parameter, and/or a rotating assembly parameter, to generate OOB output indicative of balance of laundry in the drum.

Optionally a non-rotating assembly parameter is determined from input received from a gyroscope.

Optionally the mass and/or rotating inertia is determined from input received from a weight sensor and/or motor.

Optionally a rotating assembly parameter is determined from input received from a motor.

Optionally the input received from the motor is one or more of motor current, voltage, torque, position and/or speed.

Optionally the OOB output is generated using a model.

Optionally the model is a function of: a mass and/or rotating inertia, and a relative phase between the rotating assembly motion and non-rotating assembly motion, and optionally motor speed.

Optionally relative phase between the rotating assembly motion and the non-rotating assembly motion comprises a phase difference between movement of one or more axes of the inner drum and motor and/or drum rotation.

Optionally the model comprises one or more of: equation(s), algorithm(s), numerical method(s), look-up table(s) and/or other mathematical construct(s) which can be used to process the OOB input parameters to generate the OOB outputs.

Optionally processing the OOB input parameters to generate OOB outputs comprises one or more of: simultaneously solving dynamic motion equations, and using look-up tables to retrieve appropriate values from pre-solved dynamic motion equations.

Optionally OOB output comprises one or more of: static OOB mass, dynamic OOB mass, dynamic OOB angle, a decision on existence of OOB, and/or control signal to operate the washing machine.

Optionally the method further comprises: determining whether an OOB condition exists, and/or determining the character or severity of the OOB condition if it exists.

Optionally either or both of the steps of determining whether an OOB condition exists, and/or determining the character or severity of the OOB condition if it exists comprises comparing one or more OOB outputs to a predetermined threshold or limit.

Optionally the method further comprises modifying operation of the laundry apparatus based on the OOB output.

Optionally modifying operation of the laundry apparatus comprises:

- stop or slow rotation of the drum;
- speed rotation of the drum;
- maintain the current speed of rotation of the drum;
- reverse the direction of rotation of the drum, or cause an oscillation of the drum in alternate rotational directions;
- cause the machine to enter a redistribution mode in which the drum is driven in a motion that shifts the load around the drum in order to distribute the mass of the load more evenly;
- alter the spin speed profile over the course of the wash cycle so that, for example, there is a lengthening or shortening of the time period for which the drum spins at certain speeds.

Optionally the laundry apparatus comprises a horizontal axis drum.

Optionally the laundry apparatus has a drum rotated by an axial flux motor.

Optionally the method is carried out during a spin cycle of the laundry apparatus operation, and optionally during a dehydration spin cycle.

Optionally the method is carried out during a first speed plateau of the spin cycle of the laundry apparatus operation.

In another aspect the present invention may be said to comprise a laundry apparatus comprising, a motor and drum, one or more sensors, comprising at least a gyroscope, and a controller, wherein the controller is configured to, during operation of the machine: receive output from one or more OOB sensors, determine from the OOB sensor output: a mass and/or rotating inertia, and a relative phase between a rotating assembly motion and non-rotating assembly motion, and generate OOB output indicative of balance of laundry in the drum.

Optionally the motor is an axial flux motor.

Optionally the drum is a horizontal axis drum.

Optionally the laundry apparatus further comprises determining speed from the OOB sensors.

Optionally the controller is further configured to determine an OOB condition from the OOB output.

Optionally the controller is further configured to operate the laundry apparatus to mitigate OOB laundry if it exists.

Optionally the relative phase is determined from input received from the gyroscope and motor and/or drum speed.

Optionally the laundry apparatus further comprises: a non-rotating assembly suspended within an outer cabinet, and a rotating assembly within the non-rotating assembly, wherein the drum is within the non-rotating assembly and configured to hold laundry during operation of the apparatus, and wherein the rotating assembly can be rotated relative to the non-rotating assembly by the motor.

Optionally the controller is configured to further determine from the OOB sensor output: a non-rotating assembly parameter, and/or a rotating assembly parameter, to generate OOB output indicative of balance of laundry in the drum.

Optionally the non-rotating assembly parameter is determined from input received from the gyroscope.

Optionally the laundry apparatus further comprises a weight sensor and wherein the mass and/or rotating inertia is determined from input received from a weight sensor and/or motor.

Optionally the rotating assembly parameter is determined from input received from the motor.

Optionally the input received from the motor is derived from one or more of motor current, voltage, torque, position and/or speed.

Optionally the gyroscope is mounted on the non-rotating assembly.

Optionally the OOB output is generated using a model.

Optionally the model is a function of: a mass and/or rotating inertia, and a relative phase between the rotating assembly motion and non-rotating assembly motion, and optionally motor speed.

Optionally relative phase between drum movement and motor rotation comprises a phase difference between movement of one or more axes of the drum and motor and/or drum rotation.

Optionally OOB output comprises one or more of: static OOB mass, dynamic OOB mass, dynamic OOB angle, a decision on existence of OOB, and/or control signal to operate the washing machine.

Optionally the controller is further configured to: determine whether an OOB condition exists, and/or determine the character or severity of the OOB condition if it exists.

Optionally the laundry apparatus further comprises modifying operation of the washing machine based on the OOB output.

Optionally modifying operation of the washing machine comprises:

- stop or slow rotation of the drum;
- speed rotation of the drum;
- maintain the current speed of rotation of the drum;
- reverse the direction of rotation of the drum, or cause an oscillation of the drum in alternate rotational directions;
- cause the machine to enter a redistribution mode in which the drum is driven in a motion that shifts the load around the drum in order to distribute the mass of the load more evenly;
- alter the spin speed profile over the course of the wash cycle so that, for example, there is a lengthening or shortening of the time period for which the drum spins at certain speeds.

Optionally the controller generates OOB output during a spin cycle of the laundry apparatus operation, and optionally during a dehydration spin cycle.

Optionally the controller generates OOB output during a first speed plateau of the spin cycle of the laundry apparatus operation.

In another aspect the present invention may be said to comprise a method of assessing OOB condition in a laundry apparatus comprising:

- modelling motion of a laundry apparatus as notional drum that during comprises cyclical variation of motion in a rotational frame of reference and a translation frame of reference, and making an OOB assessment of an OOB condition based on parameters indicative of cyclical variation of motion in the frames of reference, and optionally if an the OOB condition indicates an imbalance, controlling the laundry apparatus to mitigate the imbalance.

A laundry apparatus for assessing and/or mitigating OOB condition comprising: a suspended assembly comprising a rotating assembly and a non-rotating assembly, one or more sensors on the rotating and/or non-rotating assembly which provide output indicative of rotational and/or translational cyclic variation in the suspended assembly, and a controller to use the output from the sensors to: model motion of the suspended assembly as notional drum that during operation comprises cyclical variation of motion in a rotational frame of reference and a translation frame of reference, and making an OOB assessment of an OOB condition based on parameters indicative of cyclical variation of motion in the frames of reference, and optionally if an the OOB condition indicates an imbalance, controlling the laundry apparatus to mitigate the imbalance.

In another aspect the present invention may be said to comprise a laundry apparatus for assessing and/or mitigating OOB condition comprising: a suspended assembly comprising a rotating assembly and a non-rotating assembly, an axial flux motor to rotate the rotating assembly, one or more sensors, including a gyroscope on the non-rotating assembly, and a controller to use the output from the one or more sensors including the gyroscope to make an OOB assessment.

In another aspect the present invention may be said to comprise a front-loader laundry apparatus comprising: an outer cabinet, a horizontal drum in the cabinet, a direct drive axial flux motor to rotate the drum, a gyroscope to measure movement of the drum.

Optionally said laundry apparatus comprises a non-rotating assembly suspended within the outer cabinet, and a rotating assembly, comprising the drum, received within the non-rotating assembly and configured to hold laundry during operation of the apparatus, wherein rotation of the rotating assembly relative to the non-rotating assembly is directly driven by the axial flux motor.

In another aspect the present invention may be said to comprise a method of assessing out of balance in an axial flux motor horizontal axis drum laundry apparatus comprising during operation of the laundry apparatus: receiving from sensors input to determine a rotating inertia, static imbalance, dynamic imbalance and phase difference between movement of one or more axes of the drum and motor and/or speed, and generating output indicative of out of balance mass in the drum.

In another aspect the present invention may be said to comprise a method of operating an axial flux motor horizontal axis drum laundry apparatus comprising during operation of the laundry apparatus: receiving from sensors a rotating inertia, static imbalance, dynamic imbalance and phase difference between movement of one or more axes of the drum and motor and/or drum speed, and generating output indicative of out of balance mass in the drum, and modifying operation of the machine based on the output.

In another aspect the present invention may be said to comprise an axial flux motor horizontal axis drum laundry apparatus comprising a gyroscope to measure movement of the drum during operation of the laundry apparatus, and a controller configured to: receive from sensors a rotating inertia, static imbalance, dynamic imbalance and phase difference between movement of one or more axes of the drum and motor and/or drum speed, and generate output indicative of out of balance mass in the drum.

Optionally the apparatus further comprises the controller modifying operation of the laundry apparatus based on the output.

It is intended that reference to a range of numbers disclosed herein (for example, 1 to 10) also incorporates reference to all rational numbers within that range (for example, 1, 1.1, 2, 3, 3.9, 4, 5, 6, 6.5, 7, 8, 9 and 10) and also any range of rational numbers within that range (for example, 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 “comprise” and “comprised” are to be interpreted in the same manner.

This invention may also be said broadly to 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 this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

BRIEF DESCRIPTION OF DRAWINGS

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

FIGS. 1A to 1D show horizontal axis laundry apparatus in diagrammatic form, directly driven by an electric motor and with a gyroscope and controller to implement OOB assessment and/or control.

FIGS. 2A, 2B, 2C show, in diagrammatic form, how static and dynamic OOB mass and angle can be modelled to provide an indication of the balance of laundry in a laundry apparatus drum.

FIGS. 3, 4, show in diagrammatic form and flow diagram form a high level method for assessing out of balance in a laundry apparatus.

FIGS. 5, 6 show in diagrammatic form a particular example of a method for assessing out of balance in a laundry apparatus.

FIG. 7 shows motor angular position over time for a motor driving rotation of the rotating assembly of the laundry apparatus.

FIG. 8 shows the output, for x, y and z axes, of a gyroscope mounted to a non-rotating assembly of the laundry apparatus.

FIGS. 9A, 9B shows a graph of the various spin speeds versus time of a typical dehydration spin cycle during which multiple out of balance assessments are made at various time points, and an improved dehydration spin cycle according to the present embodiments.

FIG. 10A, 10B respectively show a matrix of criteria for determining and OOB condition.

DETAILED DESCRIPTION
1. Overview of General Embodiment
1.1 Out of Balance

A brief description of out of balance will be described with reference to FIGS. 2A, 2B. It should be appreciated that those skilled in the art will understand the nature of out of balance, so it does not need to be described in detail. The present method involves determining, using a model, the static and dynamic imbalance of a representative drum (“notional drum”) 1 as it spins with an out of balance load. It should be noted that an actual washing machine has a rotating inner drum 11 and a non-rotating outer drum 5, which together form part of a rotating and non-rotating assembly respectively. This combination can be more generally modelled by a notional drum 1. The notional drum 1 and the actual drums 5, 11 will be described herein.

In a horizontal axis machine, the static imbalance is a vector, the scalar quantity of which can be represented as shown in FIG. 2A, by an equivalent notional mass (“static OOB mass”) 27 located centrally along the axial direction (x-axis) of the drum, and at the drum radius R. The static OOB mass exerts a radially outward centrifugal force on the drum as it spins, and causes an oscillatory vibration of the suspended assembly in a plane orthogonal to the axis of rotation, here represented by the arrows Y and Z.

The static OOB mass 27 causes gravity to exert torque on the notional drum 1 about the axis of rotation (about the x-axis). That is, there is a negative torque (relative to the direction of rotation “m”) as the drum lifts the mass towards its highest point of the revolution, and a positive torque as the mass falls toward its lowest point of the revolution. This results in a variation in the rotational speed (i.e. angular velocity) of the drum during each revolution, and thus a cyclic variation of the rotating notional drum 1.

The dynamic imbalance is a vector, the scalar quantity of which can be represented as shown in FIG. 2B by an equivalent pair of notional masses (“dynamic OOB mass”) 28A, 28B that are equal and opposite each other rotationally, but separated axially. As the notional drum 1 rotates, the mass pair generate rocking couples about the x, y and/or z axes that cause the notional drum 1 to “wobble” or otherwise moves with a cyclic variation. Note that for some systems, the dynamic imbalance may tend to generate a rocking couple about only one, or primarily one, of either the x, y or z axis.

Note, by cyclic variation, it is not necessarily meant just rotational motion, but rather any motion that occurs according to some cyclical motion such as rotation and/or simple harmonic motion/sine wave function).

The movement of the drum when spinning in the out of balance condition is thus dependent on both the cyclic variations of the static imbalance, the cyclic (e.g. “wobbling”) variations of the dynamic imbalance and the phase difference between those two excitations, as well as the natural resonances of the suspended assembly system.

It should be appreciated that the static and dynamic OOB masses 27, 28A, 28B are not necessarily representative of the actual physical location and size of actual OOB masses in drum, but rather notional masses that provide a model which can specify notional drum 1 motion. The size and location/distribution of the OOB masses can be used to make an assessment as to whether or not the actual inner/outer drum assembly 11, 5 might be out of balance (due to an unevenly distributed real mass (i.e. laundry load)), and how severe or problematic the out of balance loading is going to be during advancement of the spin phase.

While FIGS. 2A, 2B represent static and dynamic imbalance in a horizontal axis machine, the OOB condition in a vertical axis machine can likewise be modelled in terms of static and dynamic imbalance.

FIG. 2C shows a diagrammatic representation of the static and dynamic OOB masses, which do not necessarily rotate in phase with one another. The dynamic OOB angle is the angle between the orientation of the static imbalance and the orientation of the dynamic imbalance.

So, in general terms, the method and apparatus relate to balance of a laundry apparatus that can be modelled (“out of balance model”) as a notional drum 1 with static and dynamic imbalance vectors from which cyclic variation of nominal static and dynamic masses can be determined. The cyclic variation can be rotational motion and/or other cyclical motion such as simple harmonic motion/sine wave function). This results in a cyclic variation of a rotating (could also be termed “angular”) frame of reference and a cyclic variation in a translational frame of reference (which can result in precession/wobbling). The cyclic variation provides information from which an out of balance condition can be determined (OOB assessment). From this, information, inferences of actual laundry balance/imbalance can be made and/or where imbalance exists, actions to mitigate (e.g. reduce or eliminate) the imbalance in the notional drum 1 can lead to mitigation of actual imbalance in the actual inner/outer drums 11, 5.

To model out of balance, various OOB sensors, such as one or more gyroscopes, accelerometers, IMUs, motor sensors, positional sensors, angular sensors and the like can be used to provide input information. The OOB sensors can be placed on the actual laundry apparatus in suitable locations to capture cyclic variation of the rotational and/or translation frames of reference. The OOB sensors provide OOB input parameters which can be used to model the notional drum and the static/dynamic imbalance and/or static/dynamic OOB masses and/or cyclic variation. This provides OOB output parameters, such as static OOB mass, dynamic OOB mass, and dynamic OOB angle. These are used to make an OOB assessment to determine the OOB condition (which could be imbalance, balance, or other assessment), from which laundry apparatus control strategies can be determined and/or implemented.

The examples from this point on provide description of particular sensors, their arrangements, their outputs, the types of movement of the drums and the like. These are by way of example only, and it will be appreciated at a more general level, any arrangement could be provided that implements the method and apparatus described in general terms above.

1.2 Washing Machine Apparatus with OOB Functionality

An exemplary apparatus for carrying out the method (which can comprise the model described) of the present embodiments is described in relation to FIGS. 1A to 4.

In general terms, as shown in FIG. 1A, 1B, 1C the laundry apparatus 1 (in this case a horizontal axis/front-loader laundry apparatus—but more generally could be, without any limitation, a washer, dryer or combination washer-dryer) has a motor 10, a horizontal axis internal drum 11 and an outer drum 5 suspended in an outer cabinet (“housing”) 12, a gyroscope 13, a weight sensor 14, and a motor sensor 15. The motor drives the drum 11 to rotate and rotationally oscillate in the axial direction along the x axis (see insert FIG. 1D). The output signals of the weight sensor 14 can be used to derive information representative of the drum mass and/or rotational inertia. The output signals of the motor sensor 15 (which could be an angular sensor, an angular velocity sensor, to obtain one or more of motor current, voltage, torque, position and/or speed) can be used to derive information representative of the cyclic variations in angular velocity of the inner drum 11 spinning with an out of balance load. Note, the weight sensor 14 and motor sensor 15 are optional and instead it is possible to determine load mass (and therefore load inertia) and motor speed (and therefore cyclic variations in the angular velocity of the drum) “sensorlessly” via the motor current/torque (e.g. from output from a motor controller).

Referring to FIG. 1A a laundry machine (apparatus) 1 of the horizontal-axis (also termed “front-loading”) variety is shown. The front-loading machine includes an outer cabinet 12 with a front door 3 allowing access to a perforated rotatable inner drum 11 for holding a load of laundry such as clothing for washing, and mounted within the outer cabinet to rotate about a horizontal axis (x-axis). A generally cylindrical, fixed (non-rotating) outer drum 5 for containing washing liquid is mounted (suspended, for example on springs 18) within the cabinet 12 around the rotating inner drum 11. A motor 10 is attached at the rear of the outer drum 5 to directly drive rotation of the inner drum 11 relative to the outer drum 5 about the horizontal axis.

FIG. 1B shows, in cross section, the inner and outer drums 11 and 5, and motor 10, of the laundry machine. In FIG. 1B the outer cabinet 2 is not shown. The stator 6 of the motor (shown in this Figure as an axial flux motor 7) is fixedly attached at the end of the (non-rotating) outer drum 5, for example by mounting to the bearing housing structure 16 which is held in the end wall 5a of outer drum 5. Rotor 8 external to the outer drum 5 is rotationally fixed to the outer end of a rotor shaft 9 which extends through a passage in the end of the outer drum 5 and engages with the rotating inner drum 4 at its other end. The rotor shaft 9 is mounted via at least one or more bearings 14, such as roller bearings, carried by the bearing housing component 16.

The following description refers to:

- a) the “rotating assembly”, which comprises the inner drum 11 containing a laundry load and the rotating parts of the motor 10/7 (for example the rotor 8);
- b) the “non-rotating assembly”, which comprises the outer drum 5 and fixed/non-rotating parts of the motor 10/7 (for example the stator 6) and
- c) the “suspended assembly”, which comprises the rotating assembly and non-rotating assembly which are, as an assembled unit, suspended inside of the cabinet 12.

As an example, the rotating assembly could have motion in the rotational frame of reference, and the non-rotating assembly could have motion in the translational frame of reference, although this is not essential.

It will be appreciated that the method of the present embodiments could alternatively be carried out in a laundry machine directly driven by some other type of electric motor (such as a radial flux motor), or in a machine that is not directly driven and is instead driven via a belt and/or gearbox. However, as the method relies on detecting cyclic variations (e.g. by measuring angle and/or angular velocity to obtain one or more of motor current, voltage, torque, position and/or speed)) to determine the static imbalance of the rotating inner drum 11, it may be preferred to carry out the method in a directly driven laundry machine where the rotor of the motor has a direct rigid connection to the rotating inner drum.

The embodiment shown has an axial flux motor, but that is not essential and e.g. a radial flux motor could be used for the apparatus/method described herein. However, carrying out the method in a laundry machine driven by an axial flux motor, can be beneficial because such a motor provides a higher torque (compared to a radial flux motor of similar diameter and thickness).

It will be further appreciated the method could alternatively be carried out in a machine with a vertical axis drum.

In order to carry out the method of the present embodiments, the apparatus provides a method and/or apparatus to determine various input parameters, as follows.

A method and/or apparatus is provided for determining the cyclic variation in angular velocity of the non-rotating assembly as it “wobbles” or otherwise moves with cyclic variation in 3 dimensional space. These variations can be detected by OOB sensors associated with the non-rotating assembly. For example, a gyroscope 13 (or other angular velocity sensor) is attached to the non-rotating assembly, for example, at a location along the axial length of the suspended outer drum 5, as shown diagrammatically in FIG. 1C. The rocking motion of the suspended outer drum 5 is measured by the gyroscope. During operation, the gyroscope 13 outputs a combined signal, or three separate signals, indicating the movement of the drum in the x, y and/or z axes. The axes can be seen in FIG. 1D. Generally, the output signals take the form of a sine wave, as the drum 11 moves about each axis in approximately a sinusoidal manner. An example of the output signal from a suitable gyroscope is shown in FIG. 8. The output signals of the gyroscope are used to derive information representative of the cyclic variation in the angular velocity of the non-rotating assembly.

As just one example, the gyroscope 13 could optionally be part of an Inertial Measurement Unit (IMU) which contains a 3-axis gyroscope and 3-axis linear accelerometer. It is not necessary to have a 3-axis gyroscope. It is possible to have just a 1 or 2-axis gyroscope, or a 3-axis gyroscope but only use one or two of the axis outputs. It is also not necessary to have an accelerometer. Only the gyroscope out is required for the embodiments described. However, an accelerometer can provide optional useful additional information. An IMU is suggested as one possible gyroscope component that might be used, because it is a readily available component-even if not all the functionality/output is required. Other types of gyroscope components could be used instead. The gyroscope 13 is preferably mounted to the outer drum (e.g. 5 in FIG. 1C) of the suspended assembly of the washing machine. Studying the way that the suspended assembly reacts to excitation and mounting the gyroscope so that one of its axes aligns with the drum's preferred axis of motion can make the calculation stages of the method easier.

Another method and/or apparatus is provided by which to determine the second moment of mass/rotational inertia of the notional drum 1. To this end the apparatus may have a weight sensor 14 used for determining the mass of the drum (including the clothing load and any absorbed water) and/or rotational inertia. For example, the mass sensor may be located in the feet of the washing machine, or attached at the suspension, for example, in order to measure extension of springs 18 under the weight of the load. However it is alternatively possible to use data from the motor (such as one or more of motor current, voltage, torque, position and/or speed) to estimate the mass and rotational inertia of the rotating assembly based on the torque required to accelerate the rotating inner drum 11 from a first speed to a second speed.

Another method and/or apparatus is provided by which to determine cyclic variations in the angular velocity of the rotating assembly. As explained in relation to FIG. 2A, the real mass/laundry load that the static OOB mass represents causes a cyclic variation in the angular velocity of the spinning drum. These variations can be detected by OOB sensors associated with the rotating assembly. To this end, the apparatus may have a motor speed and/or position sensor 15 use for determining the angular velocity of the motor. For example a hall effect sensor or encoder could be used. However it is alternatively possible to use data from the motor, such as current, (or some other type of sensorless control methodology) to estimate the position and/or speed of the motor.

The gyroscope 13, weight sensor 14 (if used), motor speed 15 (if used) and/or position sensor (if used) and any other component that provides information from which the OOB condition can be characterised is termed an “OOB sensor”. The OOB sensors might be used for other assessment and control also, in addition to OOB assessment and control. As described previously, the motor itself can be used as an OOB sensor, to the extent that data from the motor (such as current, torque, position, speed and temperature) can be processed to provide information which may alone, or in combination with other information, enable the OOB condition to be assessed. This might comprise determining whether an OOB condition exists, and/or determining the character or severity of the OOB condition if it exists. This might comprise comparing one or more OOB outputs to a predetermined threshold or limit.

FIGS. 10A, 10B respectively show a matrix of criteria for determining and OOB condition.

For example, referring to FIG. 10A, a two dimensional matrix 110 setting out quadrants 110A to 110B for values of static OOB mass 112 and dynamic OOB mass 113 could be used, each quadrant 110A to 110B separated by a combination of static OOB mass 114 and dynamic OOB mass thresholds 115. Depending on which quadrant 110A to 110B the combination of determined static 112 and dynamic OOB 113 masses fall, a OOB condition can be determined as existing 11A or not existing 11B, and what control should be applied (being any of those described herein).

This could be extended, for example, referring to FIG. 10B, to a three dimensional matrix 120 setting out cubic regions e.g. 120A for values of static OOB mass 112 and dynamic OOB mass 113 and dynamic OOB angle 121. Each cubic region e.g. 120A is separated by a combination of static OOB mass 114 and dynamic OOB mass 115 thresholds and a dynamic OOB angle 122 threshold. Depending on which cubic region e.g. 120A the combination of determined static 114 and dynamic OOB 113 masses and dynamic OOB angle 121 fall, a OOB condition can be determined as existing 11A or not existing 11B, and what control should be applied (being any of those described herein).

Other criteria to make OOB condition decisions could be used, and the above is by way of example only. Look-up tables, algorithms, empirical data, formula or others could be used, for example.

The apparatus also has a controller 16. The controller is connected to the motor and/or motor sensor, gyroscope, weight sensor and any other OOB sensors (e.g. accelerometers) and any other sensors of the laundry machine. The controller can provide signals to drive the motor, which in turn drives rotation of the drum. The controller is programmed among other things to receive input data, generate OOB output (to be described later) indicative of the balance of laundry in the drum, and then take appropriate action.

For example, the controller could be programmed to take one or more of the following actions:

- stop or slow rotation of the drum;
- speed rotation of the drum;
- maintain the current speed of rotation of the drum;
- reverse the direction of rotation of the drum, or cause an oscillation of the drum in alternate rotational directions;
- cause the machine to enter a redistribution mode in which the drum is driven in a motion that shifts the load around the drum in order to distribute the mass of the load more evenly;
- alter the spin speed profile over the course of the wash cycle so that, for example, there is a lengthening or shortening of the time period for which the drum spins at certain speeds.

1.3 OOB Control Method

An example of an OOB assessment method, and subsequent OOB apparatus control method of the washing apparatus 1 based on the assessment, will now be described. The assessment and subsequent apparatus control method more generally can be termed an OOB control method. The OOB control method is implemented in the controller and/or by control of various operations of the washing machine 1, such as control of the motor 10. This is just one non-limiting example.

In general terms, the controller 16 receives inputs and makes an assessment about the balance of the load in the washing machine drum. Based on the assessment, the controller 16 can then take appropriate operational actions on the washing machine.

1.3.1 OOB Assessment Method

Referring to FIGS. 3 and 4, to make the OOB assessment, the controller 16 uses the following OOB input parameters 20, which come from OOB sensors.

- Rotating inertia 20A
  - this can be determined from mass information and take the units (Kg·m²)
- Rotating assembly parameter 20B
  - One or more parameters being or indicative of rotating assembly motion, one non-limiting example being motion in a rotational frame of reference, such as magnitude and phase of cyclic variation in angular velocity of the rotating assembly.
- Non-rotating assembly parameter 20C

One or more parameters being or indicative of non-rotating assembly motion, one non-limiting example being motion in a translation frame of reference such as magnitude and phase of cyclic variation in angular velocity of the non-rotating assembly.

The rotating and non-rotating inputs can be used to determine a relative phase angle between the phase of the rotating assembly motion and phase of the non-rotating Assembly motion (“relative phase”) 20D, which is fed into the model. This could be deemed to be an OOB input parameter into the model in lieu of the rotating assembly and no-rotating assembly parameters.

In some embodiments, such as shown in FIG. 4, optionally motor (or inner drum) speed may be a further OOB input parameter. The motor speed may be ascertainable from the motor/motor sensor output and/or rotating assembly parameter, given that the motor is directly driving rotation of the rotating assembly. Alternatively there may be a separate sensor or sensor output for communicating information from which motor speed can be derived.

The controller 16 receives and processes the OOB sensor outputs (from the controller perspective, OOB sensor input) from various the sensors (e.g. sensor 13, 14, 15), step 30, to determine/generate the OOB input parameters 20, step 31. In particular, the controller 16 receives and processes the following OOB sensor input:

- the weight sensor 14 and/or motor/motor sensor 15 to determine mass and/or rotating inertia,
- the motor/motor sensor 15 to determine the rotating assembly parameter/motion,
- the gyroscope 13 to determine the non-rotating assembly parameter/motion,
- the gyroscope 13 and motor/motor sensor 15 to determine relative phase between the rotating assembly motion and the non-rotating assembly motion.
- optionally also motor current or sensor to determine motor speed

Details of how these are determined will be described later. It should be noted that in step 31, the box “calculate magnitude and phase angle” relates to the relative phase input, but also contains the rotating assembly parameter and non-rotating assembly parameter information. As will be described later, the magnitude and phase angle relating to each of the rotating and non-rotating assembly are determined by processing the OOB sensor output.

The OOB input parameters 20 are processed in a model 24 (e.g. comprising look-up tables and/or equations), step 32, in order to determine/generate one or more OOB outputs 25, step 33, being OOB output parameters and/or control signals. For example, processing the OOB input parameters to generate OOB outputs comprises one or more of: simultaneously solving dynamic motion equations, and using look-up tables to retrieve appropriate values from pre-solved dynamic motion equations. The OOB outputs are a range of parameters and/or signals which can be used to assess or characterise the out of balance condition and/or assess actions that should be taken and/or implement those actions 26, step 33.

For example, the OOB output parameters can be one or more of:

- the static OOB mass (obtained from “static imbalance” vector) (in kg·m) and/or the magnitude and direction of a force exerted by the static OOB mass during rotation (acting at the mass centre of the suspended assembly.
- the dynamic OOB mass (obtained from the “dynamic imbalance” vector) (in kg·m²) and/or the magnitude and direction of a force exerted by the pair of dynamic OOB masses during rotation; and
- the dynamic OOB angle (“phase angle”) between the orientation of the dynamic imbalance vector and the orientation of the static imbalance vector.

An OOB condition (can also be termed an OOB state) means the state of the wash load/drum—whether it is out of balance or not out of balance, or some other indicator of its balance status.

Also, for example, the OOB control signals can be anything to control an operation of the laundry apparatus in response to a OOB condition.

- stop or slow rotation of the inner drum;
- speed rotation of the inner drum;
- maintain the current speed of rotation of the inner drum;
- reverse the direction of rotation of the inner drum, or cause an oscillation of the inner drum in alternate rotational directions;
- cause the machine to enter a redistribution mode in which the inner drum is driven in a motion that shifts the load around the drum in order to distribute the mass of the load more evenly;
- alter the spin speed profile over the course of the wash cycle so that, for example, there is a lengthening or shortening of the time period for which the inner drum spins at certain speeds.

To determine OOB outputs 25, the OOB input parameters 20 are provided into a process model 24 that is implemented by the controller 16. The model 24 implements a function of the OOB input parameters as follows.

Model=f(rotating inertia,rotating assembly parameter,non-rotating assembly parameter)

Optionally speed could be used as well leading to

Model=f(rotating inertia,rotating assembly parameter,non-rotating assembly parameter,relative phase,speed)

and could comprise equation(s), algorithm(s), numerical method(s), look-up table(s) and/or other mathematical construct(s) which can be used to process the OOB input parameters 20 to generate the OOB outputs 25. The model can be based on equations which describe the motion of the notional drum 1 under OOB conditions (which can lead to inferences about the OOB condition of the actual suspended assembly), assuming it to behave as a rigid rotating body. Motion of the suspended assembly may also be described as a mass/damper/spring systems. When using a look-up table, a speed could be used in addition, for example.

The above considers processing of the rotating and non-rotating assembly parameters as part of the model. Optionally, it is possibly to characterise the model just item 24. In this case as the rotating assembly parameter and non-rotating assembly parameter are used to obtain relative phase which is fed into the model, the model could be characterised as follows.

Model=f(rotating inertia,relative phase)

Model=f(rotating inertia,relative phase,speed)

Either characterisation is valid and does not change the outcome. Insofar the model characterisation comprises the rotating and non-rotating assembly parameters as inputs, the model could be deemed to comprise as part of it the model which takes the relative phase as input.

The inputs to the model were described above, will be described in more detail later with specific examples.

The controller 16 implements the model 24 at suitable times in the laundry apparatus cycle. During those periods, the method of FIG. 4 is repeated/iterated. During the periods where the model 24 is implemented, the controller 16 can generate the OOB outputs 17 continuously or periodically, based on taking sensor 13, 14, 15 outputs or other outputs continuously or periodically.

2. Exemplary Embodiment of Washing Machine with OOB Functionality

One particular example of the general embodiment is now described with reference to FIGS. 1 to 6.

2.1 Washing Machine Apparatus

Referring to FIG. 1A, 1B, 1C, a washing machine with sensors including a gyroscope 13 is provided, as previously described.

In this embodiment, the platform is provided for the gyroscope 13 X-axis to be aligned with the axis (X-axis) of rotation of the drum 11. The gyroscope sensor is mounted on the non-rotating assembly, on a sidewall of the outer drum 5. The gyroscope sensor is part of an Inertial Measurement Unit IC (IMU) which also includes a 3-axis accelerometer, however only the gyroscope output is required for processing. If the IMU were instead mounted in the rotating reference frame, the accelerometer would show the static OOB as an acceleration vector—in this embodiment, both the rotating assembly parameter/motion and non-rotating assembly parameter/motion could be derived from a single IMU, however the difficulties of mounting and axially positioning the IMU on the motor/inner drum 11 make this alternative less attractive.

2.2 OOB Assessment Method

Referring to FIGS. 5 and 6, the controller 16 implements a dynamic behaviour model 24 on an operating basis at a suitable time in the washing machine cycle.

In one example, the method is implemented during a spin cycle (dehydration cycle). Referring to the top half of FIG. 9A, typically, a spin cycle has various stages where the drum angular velocity (spin speed) increases at each stage. As the spin speed increases, it reaches a plateau where the speed remains constant, before accelerating to a higher spin speed plateau. In prior art OOB detect mechanisms, multiple OOB decisions are be made during the cycle-typically an OOB decision is made at each plateau. The washing apparatus will not increase the spin speed to the next plateau, unless an out of balance detection is undertaken, and no out of balance is detected at a previous plateau. In many cases, the out of balance loading may not be detected until the spin speed has got up to the second, third or subsequent plateau. If that is the case, it is necessary to then take action by significantly slowing or stopping rotation of the drum at a late stage of the spin cycle. The out of balance load may shift as the drum rotation slows/stops, and then the whole process (advancing through speed plateaus with multiple OOB decisions) can be repeated again to increase the spin speed back to the maximum speed which is needed for efficient dehydration.

In contrast, in one example of the present disclosure, referring to the bottom half of FIG. 9A, the OOB method (to determine an OOB condition) is made at the first spin speed cycle plateau, but the efficacy of the method is such that the dynamic behaviour of the drum (in its present loading condition) can be more accurately predicted for subsequent/higher speeds. This may be sufficient to make a decision to push to higher spin speeds, without further OOB detection being required. This means that if OOB load mitigation is required, it can be done at the early stage when the drum is still spinning relatively slowly, rather than a later stage. OOB monitoring can still continue throughout all spin cycle stages, but there is a better chance that any out of balance is detected and mitigated much earlier.

This implementation comprises calculating the following equations in the model 24:

Model=f(rotating inertia,rotating assembly parameter,non-rotating assembly parameter)

Optionally speed could be used as well leading to

Model=f(rotating inertia,rotating assembly parameter,non-rotating assembly parameter,relative phase,speed)

Optionally, as previously described, the model could be re-characterised as:

Model=f(rotating inertia,relative phase)

Model=f(rotating inertia,relative phase,speed)

from the following inputs. In general, these inputs could be determined continuously or at discrete points in time (using a suitable sampling period), using sensors and/or sensorlessly. Below are just examples of how the parameters could be determined.

In general terms, the overall method determines model inputs (rotating assembly parameter, non-rotating assembly parameter, (or relative phase), speed), step 31, which can be termed “OOB input parameters”. Each of these OOB input parameters might take the form for example, of an OOB input signal that specifies the OOB input parameter. Model determines OOB output parameters (such as static OOB mass, dynamic OOB mass and dynamic OOB angle), step 32. Together, these can be used to determine an OOB condition (such as whether the laundry apparatus is out of balance or not) which can then be used to determine and implement a suitable control action, step 33.

2.2.1 Rotating Inertia

The mass and/or rotating inertia, of the rotating assembly may be determined by applying an acceleration to the motor 10 and observing the response of the drum 11. For example, if the motor speed is increased from 120-180 RPM, the response (e.g. lag) in the actual increase in angular velocity of the rotating assembly can be used to determine mass and/or inertia. Alternatively, the motor could be allowed to coast and the response of the drum observed. Rotating inertia is specified in kg·m².

This is just one example, and the rotating inertia could be calculated from other inputs relating to the motor, or relating to other aspects of the apparatus. In yet further variation, a weight sensor could be used to measure the mass of the load, and hence calculate the rotating inertia.

2.2.2 Rotating Assembly Parameter

Referring to FIGS. 5 and 6, the rotating assembly parameter 20B is calculated from the motor/sensor output and provided to the model 24. FIG. 5 shows the steps, while FIG. 6 shows representation of the information determined at each step.

To determine the rotating assembly parameter 20B, the controller 16 receives motor speed input 60 (in this case, angular position versus time) from the motor 10 controller and/or motor speed/angular position sensor 15 in order to determine motor speed (that is, motor angular velocity). As shown in FIG. 7, the input 60 could take the form of an angular position of the motor 10 at various points in time, which via differentiation can be converted to an angular velocity.

Referring to FIG. 6, the angular position information 60 is accumulated over time and is differentiated to provide an angular velocity (also termed “motor speed” or “drum rotation speed”) 62. The angular velocity comprises a base velocity component 63 (offset), which relates to the intended rotational speed of the motor 10/drum 11 (that is, rotational speed in normal conditions, in the absence OOB). As can be seen, the base velocity component 63 is actually increasing (increasing trend), which indicates an increase of rotational speed of the motor as the spin cycle progresses. The angular velocity 62 also comprises an oscillating (“cyclic”) component 64, that relates to the per revolution variation in angular velocity variation due to static OOB mass. That is, this is the variation as the drum 11/motor 10 speeds up and slows down as the static OOB mass rotates with the drum 11 (as previously explained in relation to FIG. 2A). The base component 63 can be filtered out (to de-trend and remove offset 61-63) from the angular velocity 62, leaving the oscillating (“cyclic”) component 64. This component 64 is a rotating assembly parameter signal (that represents a rotating assembly (OOB) input parameter−1/rev ripple magnitude and phase of angular velocity of the rotating assembly spinning about the x axis) that is provided to the model as the rotating assembly parameter 20B. This can be used to determine static OOB mass (one of the OOB output parameters 25) as will be described in the model description below.

It should be noted that the diagram in FIG. 6 is representative only of what the controller generates. It only indicates step-wise conceptually what occurs in by the controller but not necessarily what actually occurs. That is, the controller does not necessarily generate the graphs, the actual signals or all the individual steps shown. But, the controller generates an output that can be defined by those steps.

2.2.3 Non-Rotating Assembly Parameter

Referring to FIGS. 5 and 6, the non-rotating assembly parameter 20C is calculated from the gyroscope and provided to the model 24. FIG. 5 shows the steps, while FIG. 6 shows representation of the information at each step.

During operation, the gyroscope 13 outputs a combined signal, or three separate signals, indicating the movement of non-rotating assembly. The gyroscope measures tilt in the x, y and z axes. FIG. 8 shows typical outputs from a gyroscope on z, y and z axes. Generally this takes the form of a sine wave, as the drum 11 wobbles on each axis in approximately a sinusoidal manner. Since the rotating assembly moves together with the non-rotating assembly (i.e. both are part of the suspended assembly) the non-rotating assembly parameter is indicative of the motion of both the inner drum 11 and outer drum 5.

To determine the non-rotating assembly parameter 20B, the controller 16 receives sensor input 65 from the gyroscope 13. The controller can receive and process all three gyroscope signals (that is X, Y and Z axes), or just two signals for two of the axes, or just one signal for one axis. In one variation, the signal for a single (z) axis is taken. In another variation, the signal for two, (z, y axes) is taken.

For these purposes, the single, z-axis variation will be described.

The gyroscope 13 z-axis output is captured/sampled 65 and then processed. Where there is a dynamic imbalance, the output of the gyroscope 13 will be generally sinusoidal, although may have noise or other variations also, as can be seen in graph 65, FIG. 6. The signal can be filtered (de-trended and remove any offsets 66) leaving the oscillating (“cyclic”) component 66 (which in this case is the variation in angular velocity about the z-axis). This component 66 is a non-rotating assembly parameter signal (that represents a non-rotating assembly OOB input parameter−1/rev signal magnitude and phase of angular velocity of the non-rotating assembly moving about the z axis) that is provided to the model 24 as the non-rotating assembly parameter 20C. This can be used to determine dynamic OOB mass (one of the OOB output parameters 25) as will be described in the model description below.

A similar process could be undertaken on the y and/or x axes gyroscope 13 outputs also.

2.2.4 Relative Phase Angle

To determine relative phase 20D, the controller 16 looks at the phase difference between the variation in motor angular velocity (which represents the spin of the rotating assembly on the x-axis), and the variation in angular velocity detected by the gyroscope (which represents the wobbling (or other cyclic variation) movement of the notional drum 1 in the x, z and/or y axis). In this example, the z-axis movement is used. In particular, and referring to FIG. 6, the controller 16 uses the non-rotating assembly parameter signal 66 and the rotating OOB signal 64 previously determined, and determines the relative phase angle between them 68. It can do this by calculating a 1/revolution ripple magnitude and phase 67 from each signal 66, 64 and determining a phase diagram. This results in a phase difference OOB input 68 (which is a relative phase OOB input signal (that represents a relative phase OOB input parameter), which can be provided to the model 24 as the relative phase OOB input. This can be used to determine dynamic OOB angle (one of the OOB output parameters 25) as will be described in the model description below.

2.2.5 Motor Speed

Motor speed relates to the speed of the motor rotating (e.g. angular velocity) and can be measured in any suitable way, such as through motor current. In some embodiments motor speed could be determined by processing the rotating assembly parameter signal (in which case the motor speed may be represented by the base velocity component 63), however in other embodiments it may be provided as a separate signal or parameter.

2.2.5 Model

In this embodiment, the model 24 comprises a series of equations describing the motion of the rotating assembly (assuming it to behave as a rigid body both spinning about the x axis and wobbling about the z axis) which are solved simultaneously using numerical methods. If additional axes of gyroscope data are provided to the model, then the equations could be derived and solved to also take into account wobble of the drum on its other axes.

The model is a function of three OOB input parameters (or two parameters if re-characterising the model so the relative phase as an input instead of rotating/non-rotating assembly parameters), which are obtained as described above

- rotating inertia 20A
- rotating assembly parameter 20B
- non-rotating assembly parameter 20C
- relative phase between non-rotating assembly motion and rotating assembly motion 20D
- and optionally rotational speed

The equations of motion for a rotating rigid body could be derived by a skilled person or obtained from a reference (e.g. textbook) on dynamic modelling. In one variation, this model can be represented by the following equations.

Model=f(rotating inertia,rotating assembly parameter,non-rotating assembly parameter)

Optionally speed could be used as well leading to

Model=f(rotating inertia,rotating assembly parameter,non-rotating assembly parameter,relative phase,speed)

Optionally, as previously described, the model could be re-characterised as:

Model=f(rotating inertia,relative phase)

Model=f(rotating inertia,relative phase,speed)

In some embodiments the model may be solved using look-up tables to retrieve appropriate values from pre-solved equations of motion. For example, if the dynamic motion equations are pre-solved for different rotational speeds, then the appropriate values may be selected from a table based on the actual rotational speed at which the laundry machine is operating at the time the OOB assessment is made.

It will be appreciated that other equations and models can be used, that still are a function of the four parameters listed above.

Referring to FIGS. 2A and 2B, using the model the controller 16 can determine and output the following OOB output parameters 25 representative of the actual static and dynamic imbalance of the rotating assembly:

- Static OOB mass-refer to explanation in relation to FIG. 2A.
- Dynamic OOB mass-refer to explanation in relation to FIG. 2B.
- Dynamic OOB angle-refer to explanation in relation to FIG. 2C

These OOB outputs 25 are indicative of the balance (that is balanced or out of balance) of laundry in the drum. The outputs can be used to determine the existence of an OOB condition and/or determine what can be done to mitigate the OOB condition. For example, the three OOB output parameters are compared to thresholds or limits (for example, thresholds or limits that define acceptable static and dynamic OOB mass values for operation of the laundry machine at certain rotational speeds), and from that a determination is made whether the laundry apparatus is out of balance—it is, the OOB condition (status) is deemed out of balance and the appropriate control actions are taking to mitigate (which comprises reducing, resolving, improving or eliminating) OOB laundry in the drum. In another example, the OOB output parameters are placed in a matrix or other data structure, and from that OOB condition determined.

2.3 OOB Apparatus Control Method

If the laundry apparatus is out of balance, the controller 16 can operate the apparatus to do one or more of:

- stop or slow rotation of the drum;
- speed rotation of the drum;
- maintain the current speed of rotation of the drum;
- reverse the direction of rotation of the drum, or cause an oscillation of the drum in alternate rotational directions;
- cause the machine to enter a redistribution mode in which the drum is driven in a motion that shifts the load around the drum in order to distribute the mass of the load more evenly;
- alter the spin speed profile over the course of the wash cycle so that, for example, there is a lengthening or shortening of the time period for which the drum spins at certain speeds.

One or more of these actions can mitigate OOB laundry in the drum (e.g. redistributing the laundry so it is no longer clumped in one location). In general terms, mitigation involves moving the drum in an attempt to shift the laundry so it is no longer out of balance.

3. Other Embodiments and/or Variations

A laundry machine herein can cover, without any limitation, a washer, dryer or combination washer-dryer.

Also covered are any other variations that enable the use of OOB input parameters, including the use of a relative phase between rotational and translation frames of reference (e.g. between the motor speed and the x, y and/or z axis movement), as inputs to a model that can assess out of balance, which could in then be used to make appropriate control of the machine. The OOB sensors, their placement and OOB parameter inputs described are not the options. Any suitable arrangement of OOB sensors to obtain suitable OOB inputs for the model can be used. As one example, a single IMU could be used to obtain the inputs. In another options, a laundry apparatus with an axial flux motor and a gyroscope could be used.

4. Advantages

Referring to FIG. 5, the embodiments give much more information about the OOB mass size and distribution much earlier in the spin cycle. This enables an early decision about OOB condition, and enables earlier actions to be taken, which minimises disruption to the spin cycle.

- Most of the determination of how the spin cycle will perform can now be done during the first speed plateau. OOB detection will remain active for the entire spin cycle in case there is a change in load behaviour, but with a more complete characterisation of the OOB mass size and distribution at an early stage in the cycle (i.e. at a relatively low speed), behaviour throughout the spin cycle (i.e. as spin speeds increase) can be predicted with much higher accuracy
- Accurate prediction early in the spin cycle brings a change in cycle logic—at the beginning of spin, accelerate to the first plateau, measure OOB mass and distribution, and predict the outcome of the spin cycle. If the prediction is good, go ahead. If the prediction is poor, redistribute the load and try again
- Early decisions to redistribute save cycle time-redistribution is quicker and more successful with a load that has not yet been spun hard, and/or it takes less time to slow or stop the inner drum for load redistribution when the drum is only spinning at a low speed.
- More accurate determination of OOB mass and distribution may allow to remove some plateaus from the spin cycle, however these may be retained for other reasons such as spin energy optimisation

OUT OF BALANCE METHOD AND APPARATUS

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