MXPA01005051A - Method and apparatus for detecting washing machine tub imbalance - Google Patents

Abstract

A method and system for detecting an imbalance condition in a rotating washing machine tub includes receiving an indication of the actual tub rotation speed, comparing the actual tub rotation speed to a predetermined desired rotation speed to calculate a speed error, and determining maximum and minimum speed errors. The difference between the maximum and minimum speed error is calculated, and a tub imbalance condition is detected based at least in part on the calculated difference. In one embodiment, the speed error is input to a controller that produces an output used to minimize the absolute speed error. The difference between the minimum and maximum controller output is then used to determine tub imbalance. In another aspect of the invention, the method and system include receiving an indication of a power level required to achieve a given washing machine rotation speed and comparing the required power level to a predefined standard power level associated with the given rotation speed. A tub imbalance condition is detected in response to the comparison.

Description

METHOD AND APPARATUS FOR DETECTING THE UNBALANCE OF THE WASHBASIN OF A WASHING MACHINE FIELD OF THE INVENTION This invention relates generally to laundry washing machines, and very particularly, to a method and system for detecting the condition of imbalance of a tub in a washing machine.

DESCRIPTION OF THE RELATED TECHNIQUE Household and commercial laundry washers are well known. A generally cylindrical bucket or basket for holding clothing and other items to be washed is mounted rotatably within a frame. Typically, an electric motor operates the cuvette. During a wash cycle, the clothes are penetrated with water and detergent or soap to wash them. The detergent is rinsed from the clothes, then, during one or more squeg cycles, the water is extracted from the clothes by rotating the tray. One way to categorize the washing machines is by the orientation of the bucket in the washing machine. Conventional vertical axis washers have the bucket placed to rotate around a vertical axis. Items that are to be washed are loaded into the bucket through a door, which is usually located on the top of the washing machine. A vertical shaft washer bucket includes an agitator placed on it, which cleans the clothes by inserting it and taking it out of the water. Typically, an engine operates the agitator, in addition to rotating the vertically oriented pan during the squeg cycles. The motor generally operates at a constant speed, and a series of gears or bands are configured to operate the proper component at the proper time during each cycle of the washing machine. Horizontal shaft washers, which have the bowl oriented to rotate about a substantially horizontal axis, do not include a stirrer, and a variable speed motor operates the bowl. During wash cycles, the bucket of the horizontal shaft washers rotates at a relatively low speed. The speed of rotation of the bucket is such that the clothes are lifted out of the water, using deflectors distributed in the bucket, and then returned to the water when the bucket is turned. Both the vertical axis washers and the horizontal axis washers remove the water from the clothes by rotating the tray, so that a centrifugal force draws the water out of the clothes. It is convenient to turn the bucket at a high speed and extract the maximum amount of water from the clothes in the shortest possible time, thus saving time and energy. The distribution of clothes on the periphery of the bucket affects the ability of the washing machine to rotate the bucket at a high speed. Vertical shaft washers are especially susceptible to imbalance problems. Several factors contribute to this problem. For example, when a wash or rinse cycle is completed and the water is drained from the bucket, the laundry gathers at the bottom of the bucket, is not distributed throughout the bucket. In conventional washing machines, the bucket is not perfectly cylindrical; rather, it includes a shot. When turning the bucket, the clothes will stick to the sides of the bucket. However, since typically a constant speed motor operates the vertically oriented bucket, the motor quickly places the bucket at the maximum rotation speed. There is little likelihood that clothing is distributed around the periphery of the bucket, so it sticks to the walls of the bucket in an unbalanced manner. The unbalanced rotating bowl vibrates together with the frame. In conventional vertical axis washers, if the vibration is too sharp, the cuvette will trigger a switch placed inside the frame, stopping the rotation of the cuvette and activating a bucket imbalance alarm. A user can manually redistribute the wet clothes inside the bucket and restart the squeg cycle. Horizontal shaft washers are typically less vulnerable to bowl imbalances. As already discussed, the bucket of a horizontal axis washing machine is put into operation by a variable speed motor. This allows the inclusion of a distribution cycle, in which the bowl is rotated more quickly than the rotation speed of a wash cycle, but more slowly than a spin cycle. The speed of rotation of the cuvette increases gradually, until the clothes begin to "stick" to the walls of the cuvette due to the centrifugal force. The slower rotation speed allows clothes to be distributed more evenly on the walls of the bucket. Since the clothes have been distributed in the bucket, the speed is increased at a maximum rotation speed to extract the water from the clothes. Although horizontal axis washers may be less prone to bucket imbalances, they are not immune to bucket imbalance problems. If the clothes are not evenly distributed during the distribution cycle, the unbalanced load inside the cuvette will cause unwanted vibrations when the cuvette turns. Instead of applying all the power of the motor to spin the bowl at the highest possible speed, the power in the movement of the bowl and the vibrations of the frame is wasted. In this way, it is convenient to detect the presence of an imbalance condition in a rotating bucket, and take corrective measures. However, prior art methods for detecting disequilibrium conditions have long been unsatisfactory. The present invention addresses these and other drawbacks associated with the prior art.

BRIEF DESCRIPTION OF THE INVENTION In one aspect of the invention, a method for detecting an imbalance condition in the rotating bowl of a washing machine includes receiving an indication of the actual rotation speed of the bowl and comparing the actual rotation speed of the bowl with a rotation speed. desired default to calculate the speed error. The maximum and minimum speed errors are determined and the difference between the maximum and minimum speed errors is determined. A cuvette imbalance condition is detected based at least in part on the calculated difference. In another aspect of the invention, a method for detecting an imbalance condition in a rotating washing machine bucket includes receiving an indication of the power level required to achieve a given washing machine rotation speed and comparing the required power level with a level of standard predefined power associated with the given rotation speed. A cuvette imbalance condition is detected in response to the comparison. In another aspect of the invention, a system for detecting an unbalance condition for a rotating washing machine bucket includes a processor and a memory accessible by the processor. The memory stores a demand value of rotation speed. A speed sensing device is adapted to indicate the speed of rotation of the washing machine bucket. The processor is programmed to compare the speed indicated by the speed sensing device with the speed demand to calculate a speed error. The processor is further programmed to determine minimum and maximum speed errors, and calculate the difference between the minimum and maximum speed errors to detect an unbalance condition. In an alternate system, the memory stores a standard power level associated with a given rotation speed. The processor is programmed to calculate a power level required to achieve the given rotation speed of the washing machine indicated by the speed detecting device, and to compare the required power level with the predefined standard power level to detect a condition of unbalance of the bucket. In another aspect of the invention, a method for controlling a washing tub that contains laundry that is being washed is presented. The method includes receiving the indication of a first demand for rotation speed of the cuvette for a first operational cycle and receiving the indication of the actual rotation speed of the cuvette during the first operational cycle. The method also includes calculating a velocity error by determining the difference between the first demand of rotation speed and the actual rotation speed at predetermined points in at least one revolution of the first operational cycle bucket and determining the scale of speed errors . The rotation of the cuvette is affected in response to the scale of velocity errors. In another aspect of the invention, a laundry washer includes a frame, a bowl mounted rotatably within the frame, and a motor operably coupled to the bowl to rotate the bowl within the frame. The laundry washer further includes a memory that stores a rotational speed demand value and a rotational speed detecting device. A processor is programmed to detect an unbalance condition of the rotating trough, at least in part, by comparing the speed of rotation of the trough with the speed demand to calculate a speed error, determining minimum and maximum speed error values. , and calculating the difference between the maximum and minimum speed error values. In a particular embodiment, the cuvette is oriented to rotate about a substantially horizontal axis. In another embodiment, the motor comprises a switched reluctance motor. In an alternate mode, the memory also stores a standard power level associated with a given rotation speed. The processor is programmed to calculate a power level required to achieve the speed of rotation of the washing machine given by the speed sensing device, and to compare the required power level with the predefined standard power level to detect a condition of imbalance of the bucket.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of the invention will become apparent after reading the following detailed description and after referring to the drawings in which: Fig. 1 is a block diagram, schematically illustrating a system for detecting the unbalance condition of a washing tub according to an embodiment of the present invention; Figure 2 is a perspective view of a horizontal axis washer in accordance with an exemplary embodiment of the present invention; Fig. 3 is a flow diagram, illustrating a method for detecting the imbalance of the bowl of a washing machine in accordance with the present invention; Figure 4 is a block diagram illustrating the speed control circuit according to an embodiment of the present invention; Figure 5 is a specific embodiment of the speed control circuit of Figure 4; Figure 6 is a fiow diagram illustrating one embodiment of a method in accordance with the present invention. Fig. 7 is a flow chart illustrating an alternate method according to the invention for detecting and correcting the imbalance condition of a washing tub; and Figure 8 is a flow diagram illustrating a method for controlling a washing machine in accordance with the present invention.

Although the invention is susceptible to various modifications and alternate forms, the specific embodiments thereof have been shown by way of example in the drawings and are described herein in detail. It should be understood, however, that the description of the specific embodiments of the present is not intended to limit the invention to the particular forms described, but on the contrary, the intention is to cover all the modifications, equivalents and alternatives included in the purpose and scope of the invention. the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION The illustrative embodiments of the invention are described below. For a better understanding, all the characteristics of a real implementation in this specification are not described. Of course, it should be noted that in the development of any real modality, numerous specific implementation decisions must be made to achieve the specific goals of those who develop the invention such as compliance with the restrictions related to the system and the industry, which will vary from one to the other. implementation to another. It will also be appreciated that such a development effort can be complex and time consuming, but nevertheless, it would be a routine practice for those skilled in the art to have the benefit of this description.

Figure 1 is a block diagram, schematically illustrating a washing machine 100 in accordance with one embodiment of the present invention. The washing machine 100 includes a frame 102, in which a bowl 104 is rotatably mounted. In an embodiment of the invention, the washing machine 100 is a horizontal axis washing machine. In other words, the basin 104 is configured to rotate about a substantially horizontal axis within the frame 102. Figure 2 illustrates a horizontal axis washer 101 in accordance with a specific embodiment of the invention. Referring again to Figure 1, a motor 106 operably connects to the basin 104 to operate the basin 104, for example, by means of a band. The machine 100 further includes a memory 108 that stores a demand value of rotation speed. A speed detecting device 110 is coupled to the motor 106 to set the actual speed of the motor 106, and therefore, the rotational speed of the cuvette 104. Alternatively, the speed detecting device 110 may be directly coupled to the cuvette 104 for detect its rotation speed. In other embodiments, the rotation speed of the motor 106 and therefore of the cuvette 104 is determined without the use of sensors by monitoring the electrical and magnetic parameters of the motor 106. An example of such operation without sensors is described in FIG. the US patent No. 5,701, 064 granted to the beneficiary of the present application, which is included herein as a reference in its entirety.

A processor 112 is programmed to detect an unbalance condition of the rotating trough 104, based at least in part on the difference between the actual speed of rotation of the trough 104 (as detected by the device 110) and the stored speed demand. in the memory 108. In one embodiment of the invention, the processor 112 is programmed according to the method illustrated in Figure 3 to determine the unbalance condition of the cuvette 104. Referring to the flow diagram of Figure 3, a indication of the actual rotation speed of cuvette 104 is received in block 120. In block 122, a speed error is calculated by comparing the actual rotation speed, as determined in block 102, with the stored speed demand in memory 108. In other words, the actual rotation speed is subtracted from the speed demand to obtain the speed error. In block 124 the maximum and minimum speed errors are determined. In particular embodiments this is done for each revolution of the cuvette 104. In block 126, the difference between the maximum and minimum velocity errors is calculated to determine the disequilibrium condition. The difference between the maximum and minimum velocity errors calculated in block 126 provides an indication of the degree to which cuvette 104 is out of balance; the greater the difference between the maximum and minimum speed errors, the greater the imbalance of the cup 104. In an example embodiment of the invention, the washing machine 100 includes a control that controls the speed of rotation of the cup 104. Figure 4 illustrates a speed control circuit 130 used in an embodiment of the invention. The speed demand 132, as stored in the memory 108, is compared to the actual rotation speed 134, as indicated by the device 110, at a summation point 136 to produce the speed error 138. The speed error 138 one enters a controller 140, which produces an output power 142 that is applied to the motor 106 to correct the speed error 138. The controller 140 is effective to keep the speed error low. In this way, the maximum and minimum output power 142 of the controller 140 can be used to detect an unbalance condition. Figure 5 illustrates a proportional-integral-derived (PID) rate control circuit 150, which is used in a specific embodiment of the invention. The speed control circuit 150 is implemented in a computer program by means of the processor 112, which, in this example embodiment, comprises a microcontroller. A Motorola microcontroller model MC68HC05P9 is a suitable processor. The Motorola MC68HC05P9 microcontroller includes a memory on chip; therefore, the memory 108 is contained within the processor 112. In a mode using the PID speed control circuit 150 shown in Fig. 5, the motor 106 comprises a switched reluctance motor as is known in the art. A reluctance motor is an electrical machine whose torque is produced by the tendency of a moving part to move to a position in which the inductance of an energized winding increases to the maximum (i.e. the reluctance is minimized). The switched reluctance motor is generally constructed without conductive windings or permanent magnets in the rotating part (called a rotor) and includes electronically connected windings that carry unidirectional currents in the stationary part (called the stator). Commonly, diametrically opposed pairs of pole stators can be connected in series or in parallel to form a phase of a potentially multi-phase switched reluctance motor. The torque develops by applying a voltage to each of the phase windings in a predetermined sequence synchronized with the angular position of the rotor so that a magnetic force of attraction results between the poles of the rotor and stator as they approach each other. In this way, In a switched reluctance machine, a rotor position detector is typically used to provide signals corresponding to the angular position of the rotor, so that the phase windings can be properly energized as a function of the rotor position. The rotor position detector can take several forms. In some systems, the rotor position detector may comprise a rotor position transducer that provides output signals that change state each time the rotor rotates to a position where a different switching setting of the devices in the rotor is required. power converter. In other systems, the rotor position detector may comprise a relative position encoder that provides a pulse (or similar signal) each time the rotor rotates through a preselected angle. In one embodiment of the present invention utilizing a switched reluctance motor, the output power of the rotor position detector functions as a tachometer that generates a speed feedback signal 152, which indicates the speed of the motor 106, and thus Thus, the speed of rotation of the cup 104. In an example speed detector system, the rotor position sensor for the motor 106 provides 48 pulses per revolution of the motor 106. The 48 pulses per revolution of the rotor position sensor they are divided by the controller chip (not shown) of the motor 106 in 8 pulses per revolution. These 8 pulses are provided to the processor 112. The washing machine uses a belt drive to rotate the bucket 104, the system having a belt ratio of 12: 1. In this way, there are 96 pulses of the tachometer per revolution of the cuvette 104 provided to the processor 112. However, the present invention is not limited to the detection of a speed like this. One skilled in the art could determine the actual rotation speed of the cuvette using other procedures than a tachometer. For example, in another example embodiment using a sensor-reluctance reluctance motor, 8 pulses per revolution are provided based on the motor speed determined by parameters of the motor being examined. In embodiments using an induction motor to operate the cuvette 104, the slip can be examined to determine the velocity.

The feedback from the tachometer 152, which indicates the actual speed, is compared to the speed demand 132 at the summation point 136 to produce the speed error 138. The speed error 138 is applied to the proportional modes 154, integral 156 and derivative 158 of the controller and the PID action is summed at the summation point 160. The output power of the controller is a torque demand 162 which is required to correct the speed error 138. The controller 140 is effective in maintaining the error of speed 138 as a low signal. The output power of the controller 140 is sufficient to counteract the tendency of the speed to change. Then the difference between the maximum and minimum output power of the controller 140 directly indicates the imbalance. In other embodiments, each of the proportional modes 154, integral 156 and control derivative 158 are not used in the speed control circuit 150. For example, it would be a routine practice for one skilled in the art to have the benefit of This explanation will implement the invention using only a proportional control action. Fig. 6 illustrates an exemplary method, used with a mode using a speed control circuit as shown in Fig. 5. During each revolution of the trough 104 of a washing machine each demand signal of the torque 162 is captured and compared to determine the demands of the maximum and minimum torque 162 in block 170. The scale of demand signals of the torque 162 for each revolution of the trough 104 are determined in block 172 subtracting the minimum demand of the torque 162 of the maximum torque demand 162. In alternate modes, the maximum or minimum torque demand is not determined during each revolution of the bucket. Instead, it is determined during some preset revolutions, for example, any other revolution, or any half revolution. In other embodiments, the minimum and maximum torque demand can be determined periodically, for example, at predetermined intervals. The memory 108 comprises a predetermined standard torque demand scale, to which the difference between the minimum and maximum torque demand is compared to the standard torque demand scale in block 174 during distribution. In decision block 176, processor 112 determines whether the actual scale exceeds the standard. If the real scale is within the standard, the operation continues. If the actual scale exceeds the standard, a corrective action can be taken in block 178. For example, if the actual torque demand scale exceeds the standard, the clothes can be turned over again, and then the cycle can be restarted. distribution. This often corrects the imbalance. Alternatively, the distribution chute may be modified to better balance the cuvette 104. Furthermore, since the minimum and maximum torque demands are determined at a plurality of angular locations based on feedback from the tachometer 152, the unbalance position of the tachometer can be determined. the cuvette 104. For example, the information related to the angular position of the minimum and maximum demands of the torque on the torque demand scale, for a given load, can be related empirically to angular positions of load imbalance. These relationships can be provided in a query box stored in memory 108 and accessed by processor 112 to implement corrective measures at specific unbalance points. This may be necessary, for example, if the bucket is not balanced at the factory. It should be noted that using the output power 142 or torque demand 162 to determine the unbalance can cause a phase change in the estimated position of an equilibrium. However, an expert in the art could compensate for this phase change by knowing the controller's time constants and other controller parameters. As described in the background of the invention of the present, washing machines typically include a variety of operating cycles. Washers (particularly horizontal shaft washers) include one or more washing cycles, distribution cycles and squeezing cycles. The above-described method for detecting the unbalance can be used during any cycle of the washing machine, although unbalance of the tray is an uncommon problem during the washing cycles, in which, in a washing machine with horizontal axis, a speed of bucket rotation of approximately 50 rpm to turn the clothes in and out of the water.

The method described in conjunction with Figure 3 and Figure 5 is particularly suitable for distribution cycles, which typically operate at a cup rotation speed of about 55 to 110 rpm (clothes will begin to "stick" to the walls of the tray 104 at approximately 60 rpm). In comparison, the minimum speed of rotation that is normally considered a "squeezing cycle" is approximately 250 rpm. In a particular embodiment of the invention, a rotation speed of the cuvette of approximately 350 to 450 is considered a "low" rotation speed, a rotation speed of the cuvette of approximately 650 to 850 is considered an "average rotation speed". "and approximately 1000 rmp are considered a" high "rotation speed. As already discussed above, it is convenient to rotate the cup 104 at a high speed to extract the maximum amount of water from the clothes. At high speeds of rotation of the cuvette of a squeezing cycle, it may be difficult to implement the method illustrated in Figure 3 or Figure 5, depending on the speed of the procedure and the available power. Figure 7 illustrates another method in accordance with the present invention for detecting the unbalance of a washing machine bucket. The embodiment illustrated in Figure 7 is especially suitable for use with high rotation speeds of a spin cycle, although the method can be applied to other cycles, such as a wash cycle. In block 200, an indication of the power required to achieve a rotation speed of the given cuvette is received. In a particular embodiment, the indication of the power level is obtained during the acceleration of the cuvette 104. In the block 202, the power level received in the block 200 is compared to a predetermined "normal" power level or level scale. of power required to achieve the requested speed with a given load. As shown in decision block 204, if the actual power level exceeds the standard power level for the given speed demand, a corrective measure is taken in block 206. If the actual power does not exceed the standard power level the system continues in operation. Figure 8 illustrates a method for controlling a washing machine in accordance with one embodiment of the invention. In this exemplary embodiment, the washing machine is a horizontal axis washing machine that includes at least one first and second cycles, which may respectively comprise distribution and squeezing cycles. For the distribution cycles, in which the speed of rotation of the cuvette gradually increases until the clothes "stick" to the walls of the cuvette, a procedure is basically used as shown in figure 5 to detect a bucket imbalance condition. For squeezing cycles, in which the bowl is rotated at a high speed to remove the water from the clothes, a procedure as illustrated by the lines of figure 7 is used. In block 210, a cycle of distribution. The minimum torque demand 162, as emitted by the PID control circuit 150, is subtracted from the maximum torque demand to determine the torque demand scale in block 212. In decision block 214, the The torque demand scale is compared to a standard demand for the predetermined torque, and if the torque demand scale exceeds the standard, a corrective measure is taken. In one embodiment, the clothing is rotated again and the distribution cycle illustrated in block 216 is restarted. If the torque demand scale does not exceed the standard, the distribution cycle continues until the clothes are distributed to the consumers. sides of the trough 104, illustrated in block 218. When the laundry is properly distributed, the squeezing cycle (block 220) begins by increasing the speed of rotation of the trough 104 at the desired rotation speed in block 222. In block 224, the demand of the average torque 162 is monitored at various speeds to determine the power. The power is monitored in order to determine if excessive power is required for a given rotation speed with a given load. In decision block 226, the power for the given speed is compared to a standard or "normal" power level for the given speed. If the actual power exceeds the standard, power is being wasted in the vibration of the cuvette 104, instead of being supplied to the load. Thus, if the actual power does not exceed the standard, the squeeze cycle continues in block 228. If the actual power exceeds the standard in decision block 226, a corrective measure is taken. In this example embodiment, the laundry returns to a washing speed in block 230, and the distribution cycle is repeated. Other corrective measures can be used in alternative modalities; for example, reducing the rotation speed. Since some embodiments according to the invention described herein use the output power of the controller 140, the unbalance condition can be determined at any point during a particular cycle of the washing machine. It is not necessary for cuvette 104 to be rotating "at speed" (the desired dispensing or squeezing speed) to implement the methods of the present invention. Rather, an imbalance condition can be detected at any point after the cuvette 104 begins to rotate. Furthermore, the actual speed can be compared with any pre-selected speed demand 132. This allows the imbalance condition to be detected and corrected as soon as possible in the cycle, reducing wasted energy and other problems associated with unbalance conditions. Those skilled in the art having the benefit of this disclosure will be able to observe that the embodiment illustrated above is capable of numerous variations without departing from the scope and purpose of the invention. It is fully intended that the invention for which this patent is sought encompasses all variations within its scope without being limited to the specific embodiment described above. Accordingly, the exclusivity rights sought to be patented are as described in the following claims.

Claims (43)

NOVELTY OF THE INVENTION CLAIMS

1. - A method for detecting an imbalance condition in a rotating washing machine bucket, the method comprising: receiving an indication of the actual rotation speed of the bucket; comparing the actual rotation speed of the cuvette with a predetermined desired rotation speed to calculate the velocity error; determine the maximum and minimum speed errors; calculate the difference between the maximum and minimum speed error; and detecting a cuvette imbalance condition based at least in part on the calculated difference.

2. The method according to claim 1, further characterized in that detecting the imbalance condition of a cuvette based at least in part on the calculated difference includes: comparing the difference between the maximum and minimum velocity errors to a predetermined limit; and detect the imbalance condition of the cuvette in response to the comparison.

3. The method according to claim 1, further characterized in that the unbalance condition is detected during a cycle of the selected washing machine of at least one of a washing cycle, a distribution cycle and a squeezing cycle.

4. - The method according to claim 1, further characterized in that the errors of maximum and minimum speed are determined during a predetermined number of revolutions of the washing machine bowl.

5. The method according to claim 4, further characterized in that the predetermined revolutions of the washing bowl of the washing machine each comprise a washing machine revolution.

6. The method according to claim 4, further characterized in that the revolutions of the predetermined washing tub each comprise half a revolution of the washing tub.

7. The method according to claim 1, further characterized in that receiving an indication of the actual rotation speed of the cuvette comprises receiving feedback from a tachometer.

8. The method according to claim 1, further characterized in that comparing the actual rotation speed of the cuvette with a predetermined desired rotation speed comprises comparing the actual rotation speed of the cuvette with one of a plurality of rotation speeds desired defaults.

9. The method according to claim 1, further characterized in that it comprises: applying the speed error to a controller that provides an output signal; further characterized in that determining the maximum and minimum speed errors comprises determining the maximum and minimum controller output signals. 1.

The method according to claim 9, further characterized in that applying the speed error to a controller comprises applying the speed error to at least one of a proportional mode, an integral mode and a derivative mode.

11. The method according to claim 1, further characterized in that it comprises determining an angular location of the unbalance condition.

12. A method for detecting an imbalance condition in a rotating washing machine bucket, comprising the method; receiving an indication of a power level required to maintain a given rotation speed of a washing machine; comparing the required power level with a predefined standard power level associated with the given rotation speed; and detecting a bucket imbalance condition in response to the comparison.

13. The method according to claim 12, further characterized in that the indication of the power level is determined when the bucket of the washing machine is accelerating.

14. The method according to claim 12, further characterized in that the unbalance condition is detected during a washing machine cycle selected from at least one of a washing cycle., a distribution cycle and a squeezing cycle.

15. The method according to claim 12, further characterized in that the given speed comprises a preselected speed of a plurality of desired predetermined rotation speeds.

16. The method according to claim 12, further characterized in that receiving an indication of the power level includes determining the required torque demand for the given speed.

17. A method for detecting an imbalance condition in a rotating washing machine bucket, the method comprising: receiving an indication of the actual speed of rotation of the bucket; comparing the actual rotation speed of the cuvette with a predetermined desired rotation speed to calculate the velocity error; apply the speed error to a controller that provides an output signal; determine maximum and minimum controller output signals; and detecting an imbalance condition of the cuvette based at least in part on the difference between the maximum and minimum controller output signals.

18. The method according to claim 17, further characterized in that applying the speed error to a controller comprises applying the speed error to at least one of a proportional mode, an integral mode and a derived mode.

19. - A system for detecting an imbalance condition for a rotating bucket of a washing machine, comprising: a processor; a memory accessible by the processor and storing a demand value of rotation speed; and a speed sensing device adapted to provide an indication of the speed of rotation of the cuvette to the processor; being the processor programmed to compare the rotation speed of the bucket with the speed demand to calculate the speed error, determine maximum and minimum speed errors, and calculate the difference between the maximum and minimum speed errors to detect a condition of imbalance.

20. The system according to claim 19, further characterized in that the memory stores a predetermined speed error limit; further characterized in that the processor is programmed to compare the difference between the maximum and minimum speed errors with the predetermined limit.

21. The system according to claim 19, further characterized in that the processor is programmed to determine the maximum and minimum speed error values during a predetermined number of revolutions of the cuvette.

22. The system according to claim 21, further characterized in that the processor is programmed to determine the minimum and maximum speed error values during each revolution of the cuvette.

23. - The system according to claim 21, further characterized in that the processor is programmed to determine the maximum and minimum speed error values during each half revolution of the cuvette.

24. The system according to claim 19, further characterized in that the rotation speed detecting device comprises a tachometer.

25. The system according to claim 19, further characterized in that it comprises a controller, the controller emitting a torque demand signal based at least in part on the speed error; programmed the processor to determine the demand signals of the maximum and minimum torque.

26. The system according to claim 25, further characterized in that the controller includes at least one of a proportional mode, an integral mode and a derivative mode.

27.- A system for detecting an imbalance condition for the rotating bucket of a washing machine, comprising: a processor; a memory accessible by the processor and storing a standard power level associated with a given rotation speed; and a speed sensing device adapted to indicate the speed of rotation of the washing tub; the processor being programmed to calculate a power level required to achieve the given rotation speed of the washing machine indicated by the speed detecting device, and compare the required power level with the predefined standard power level to detect an unbalanced condition.

28. The system according to claim 27, further characterized in that it comprises a controller that emits a torque demand signal; The processor is programmed to determine the required power based on the torque demand and the speed indicated by the speed sensing device.

29. The system according to claim 28, further characterized in that the controller includes at least one of a proportional mode, integral mode and a derived mode.

30. A method for controlling the bucket of a washing machine that contains articles to be washed, the method comprising: receiving an indication of a first demand for rotation speed of the bucket for a first operational cycle; receive an indication of the actual rotation speed of the cuvette during the first operational cycle; calculating a velocity error by determining the difference between the first rotational speed demand and the actual rotational speed at predetermined points in at least one revolution of the first operational cycle cuvette; determine the scale of speed errors; and affect the rotation of the bucket in response to the scale of speed errors.

31. The method according to claim 27, further characterized in that at least one cell revolution comprises each cell revolution of the first cycle of operation.

32. - The method according to claim 27, further characterized in that it comprises: receiving an indication of a second demand for rotation speed of the cell for a second operational cycle; determine the power required to achieve the second speed; and affect the rotation of the bucket in response to the power required to achieve the second speed.

33.- A clothes washer that includes: a frame; a bucket mounted rotatably within the frame; a motor operably coupled to the bowl to rotate the bowl within the frame; a memory that stores a demand value of rotation speed; a rotation speed detecting device; a processor programmed to detect an unbalance condition of the rotating trough, at least in part by comparing the rotation speed of the trough with the speed demand to calculate a speed error, determining minimum and maximum speed error values and calculating the difference between the minimum and maximum speed error values.

34. The laundry washing machine according to claim 33, further characterized in that the memory stores a predetermined speed error limit; further characterized in that the processor is programmed to compare the difference between the maximum and minimum speed errors with the predetermined limit.

35. - The laundry washing machine according to claim 33, further characterized in that the motor comprises a switched reluctance motor.

36.- The laundry washing machine according to claim 35, further characterized in that the switched reluctance motor includes a rotor position sensor that indicates the speed of the motor.

37.- The clothes washer according to claim 35, further characterized in that the switched reluctance motor is adapted to determine the motor speed based on the operating parameters of the motor.

38.- The laundry washing machine according to claim 35, further characterized in that the rotation speed detecting device comprises a tachometer.

39. The laundry washing machine according to claim 35, further characterized in that it comprises a controller, the controller emitting a torque demand signal based at least in part on the speed error; the processor being programmed to determine the minimum and maximum torque demand signals and furthermore characterized in that the memory stores a predetermined torque demand limit and the processor is programmed to compare the difference between the demand signals of the maximum motor torque and minimum with the predetermined limit.

40. - The laundry washing machine according to claim 39, further characterized in that the controller includes at least one of a proportional mode, an integral mode and a derivative mode.

41. The laundry washing machine according to claim 35, further characterized in that the trough is oriented to rotate about a generally horizontal axis.

42. The clothes washer according to claim 35, further characterized in that the trough is oriented to rotate about a generally vertical axis.

43. The clothes washer according to claim 35, further characterized in that the memory also stores a standard power level associated with a given rotation speed; the processor is further programmed to calculate a power level required to achieve the given rotation speed of the washing machine indicated by the speed detecting device and to compare the required power level with the predefined standard power level to detect a condition of unbalance of the bucket.