Washing machine appliance out-of-balance detection

1. A method for operating a washing machine appliance, the washing machine appliance having a tub and a basket rotatably mounted within the tub, the basket defining a chamber for receipt of articles for washing, the method comprising:

flowing a volume of liquid into the tub;

agitating articles within the tub for a first period, the tub containing the volume of liquid;

draining a first portion of the volume of liquid from the tub, the first portion less than the volume flowed into the tub, wherein a sum of the first portion and a second portion of the volume of liquid remaining in the tub equals the volume;

measuring movement of the tub during agitation of the articles within the tub after draining the first portion of the volume of liquid from the tub, wherein the step of measuring movement occurs after agitating articles within the tub for the first period and for an intermediate measurement period;

agitating articles within the tub for a second period when the final measured movement is greater than an out-of-balance movement threshold;

draining liquid from the tub when the final measured movement is less than the out-of-balance movement threshold; and

spinning the basket after draining liquid from the tub,

wherein agitating articles within the tub comprises redistributing the articles during a tumbling cycle within the tub through a repeated starting-stopping pattern of agitation strokes according to a corresponding agitation profile prior to the draining liquid from the tub.

2. The tub of claim 1 , wherein the tub contains only the second portion of the volume of liquid during the step of agitating articles within the tub for the second period.

3. The tub of claim 1 , wherein additional liquid is flowed into the tub after the measuring step and before the step of agitating articles within the tub for the second period, and wherein the additional liquid is flowed into the tub when the final measured movement is greater than an out-of-balance movement threshold.

4. The tub of claim 1 , wherein the first portion is less than or equal to 60% of the volume.

5. The method of claim 1 , wherein, during the step of measuring movement, agitating of the articles is actively ceased upon determination that the measured movement is less than the out-of-balance movement threshold.

6. The method of claim 1 , wherein the movement is measured using an accelerometer.

7. The method of claim 1 , wherein movement is measured using at least one of an accelerometer, a gyroscope, an optical sensor, an inductive sensor, a Hall effect sensor, a potentiometer, a load cell, or a strain gauge.

8. The method of claim 1 , wherein the movement is measured using an accelerometer and a gyroscope.

9. The method of claim 8 , wherein the tub defines an X-axis, a Y-axis and a Z-axis which are mutually orthogonal to each other, the Z-axis extending along a longitudinal direction and defining a center of the tub, and wherein the gyroscope measures movement about the Z-axis.

10. The method of claim 9 , wherein the movement measured by the accelerometer is measured in a plane defined by the X-axis and Y-axis and along a direction perpendicular to a vector that passes through the center.

11. A washing machine appliance, comprising:

a tub;

a basket rotatably mounted within the tub, the basket defining a wash chamber for receipt of articles for washing;

a valve;

a nozzle configured for flowing liquid from the valve into the tub;

an agitation element;

a measurement device mounted to the tub;

a motor in mechanical communication with the basket, the motor configured for selectively rotating the basket within the tub and further configured for selectively rotating the agitation element; and

a controller in operative communication with the valve, the motor and the measurement device, the controller configured for:

flowing a volume of liquid into the tub;

agitating articles within the tub for a first period, the tub containing the volume of liquid;

draining a first portion of the volume of liquid from the tub, the first portion less than the volume flowed into the tub, wherein a sum of the first portion and a second portion of the volume of liquid remaining in the tub equals the volume;

measuring movement of the tub during agitation of the articles within the tub after draining the first portion of the volume of liquid from the tub, wherein the step of measuring movement occurs after agitating articles within the tub for the first period and for an intermediate measurement period;

agitating articles within the tub for a second period when the final measured movement is greater than an out-of-balance movement threshold;

draining liquid from the tub when the final measured movement is less than the out-of-balance movement threshold; and

spinning the basket after draining liquid from the tub

wherein agitating articles within the tub comprises redistributing the articles during a tumbling cycle within the tub through a repeated starting-stopping pattern of agitation strokes according to a corresponding agitation profile prior to the draining liquid from the tub.

12. The washing machine appliance of claim 11 , wherein the tub contains only the second portion of the volume of liquid during the step of agitating articles within the tub for the second period.

13. The washing machine appliance of claim 11 , wherein additional liquid is flowed into the tub after the measuring step and before the step of agitating articles within the tub for the second period, and wherein the additional liquid is flowed into the tub when the final measured movement is greater than an out-of-balance movement threshold.

14. The washing machine appliance of claim 11 , wherein the first portion is less than or equal to 60% of the volume.

15. The washing machine appliance of claim 11 , wherein, during the step of measuring movement, agitating of the articles is actively ceased upon determination that the measured movement is less than the out-of-balance movement threshold.

16. The washing machine appliance of claim 11 , wherein the measurement device includes an accelerometer, and wherein the movement is measured using the accelerometer.

17. The washing machine appliance of claim 11 , wherein the measurement device includes at least one of an accelerometer, a gyroscope, an optical sensor, an inductive sensor, a Hall effect sensor, a potentiometer, a load cell, or a strain gauge, and wherein the movement is measured using at least one of the accelerometer, the gyroscope, the optical sensor, the inductive sensor, the Hall effect sensor, the potentiometer, the load cell, or the strain gauge.

18. The washing machine appliance of claim 11 , wherein the measurement device includes an accelerometer and a gyroscope, and wherein the movement is measured using the accelerometer and the gyroscope.

19. The washing machine appliance of claim 18 , wherein the tub defines an X-axis, a Y-axis and a Z-axis which are mutually orthogonal to each other, the Z-axis extending along a longitudinal direction and defining a center of the tub, and wherein the gyroscope measures movement about the Z-axis.

20. The washing machine appliance of claim 19 , wherein the movement measured by the accelerometer is measured in a plane defined by the X-axis and Y-axis and along a direction perpendicular to a vector that passes through the center.