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A laundry machine includes a drum supported at least two spaced apart support locations for rotation about a rotation axis. A balance correction system is able to apply a variable amount of a balance correction mass at a selectable angular location of the drum at least two spaced apart locations alo

A laundry machine includes a drum supported at least two spaced apart support locations for rotation about a rotation axis. A balance correction system is able to apply a variable amount of a balance correction mass at a selectable angular location of the drum at least two spaced apart locations along the drum rotation axis. A controller receives outputs of a set of sensors, and is programmed to continuously calculate balance corrections to apply.

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1. A laundry machine comprising: a drum for holding a laundry load, the drum supported at at least two spaced apart support locations for rotation about a rotation axis,sensors collectively providing: output from which a force component of a supporting force on parallel axes at the two spaced apart

1. A laundry machine comprising: a drum for holding a laundry load, the drum supported at at least two spaced apart support locations for rotation about a rotation axis,sensors collectively providing: output from which a force component of a supporting force on parallel axes at the two spaced apart support locations can be derived,output from which an acceleration component of acceleration of the two spaced apart support locations on the parallel axes can be derived,output from which angular velocity of said drum rotation axis can be derived, the derived angular velocity being about an axis perpendicular to the drum rotation axis, parallel to the axes of the force component and through the centre of mass of the drum and any held laundry load, wherein the sensor output from which the angular velocity is derived results from motion of the support locations perpendicular to the drum rotation axis,output from which a mass of the rotating drum and/or laundry load, and the axial location along the drum rotation axis of the centre of mass of the drum and/or laundry load, can be continuously derived,a balance correction system able to apply a variable amount of a balance correction mass at a selectable angular location of the drum at at least two spaced apart locations along the drum rotation axis, anda controller receiving outputs of the sensors, and programmed to continuously calculate balance corrections to apply, the calculation accounting for: a) an effect of acceleration of the support locations on the derived force component,b) an effect conservation of angular momentum has on the force component sensor output due to the angular velocity of the drum rotation axis about the axis through the drum and/or laundry load's centre of mass, perpendicular to the drum rotation axis and parallel to the force component axes, andc) an effect the axial location of the centre of mass of the rotating drum and/or laundry load has on the effects in a) and b). 2. The laundry machine as claimed in claim 1, wherein the sensors comprise: first sensors at the two spaced apart support locations, measuring forces such that the force component on parallel axes at the locations can be derived,second sensors at two spaced apart locations, providing output from which the acceleration component on the parallel axes at the locations of the second sensors can be derived,a third sensor or sensors, providing output from which the angular velocity of the drum rotation axis about the axis through the drum and any held laundry load's centre of mass, perpendicular to the drum rotation axis and parallel to the force component axes can be derived,a fourth sensor or sensors providing output from which the mass of the rotating drum and/or laundry load, and the axial location along the drum rotation axis of the centre of mass of the drum and/or laundry load, can be derived,the sensors not necessarily being individual relative to each other. 3. The laundry machine as claimed in claim 1, wherein the calculation estimates forces induced due to movement of the support locations in line with the force component axes. 4. The laundry machine as claimed in claim 1, wherein the calculation estimates forces induced due to movement of the support locations in a plane transverse to the force component axes. 5. The laundry machine as claimed in claim 4, wherein the calculation estimates forces induced due to movement of the support locations in a plane transverse to the force component axes as the product of a mass and inertia term and an acceleration term. 6. The laundry machine as claimed in claim 5, wherein the mass and inertia term accounts for the effect at each support location of movement applied at that support location and movement applied at the other support location based on reaction around the derived axial location along the drum rotation axis of the centre of mass of the drum and/or load. 7. The laundry machine as claimed in claim 5, wherein the acceleration term accounts for the movement on the force component axes and movement transverse to the force component axes. 8. The laundry machine as claimed in claim 7, wherein the acceleration term accounts for movement transverse to the force component axes by allocating a proportion of the total angular acceleration to each support location based on the derived axial location along the spin axis of the centre of mass of the drum and/or load between the support locations. 9. The laundry machine as claimed in claim 1, further including a support frame for the drum, and first and second bearings supporting the drum to rotate about a horizontal axis, wherein the bearings are rigidly, or substantially rigidly, supported in the support frame. 10. The laundry machine as claimed in claim 9, wherein the sensors include a first horizontal accelerometer sensing horizontal acceleration of the first bearing and a second horizontal accelerometer sensing horizontal acceleration of the second bearing. 11. The laundry machine as claimed in claim 1, further including balancing chambers distributed around each of two ends of the drum and water supply paths to transmit water to selected balancing chambers. 12. The laundry machine as claimed in claim 11, wherein the controller selectively supplies water to the balance chambers in each spin cycle, after calculating the required balance requirements, where the controller uses a physical model of the machine dynamics and calculates an absolute balance requirement accounting for accelerations that are being created or resisted in the vertical direction at each support location due to rotation or oscillation of the rotating drum in the horizontal plane. 13. The laundry machine as claimed in claim 12, wherein the controller estimates oscillation of the rotating drum in the horizontal plane from horizontal accelerations at the support locations. 14. The laundry machine as claimed in claim 13, wherein the controller converts the estimated oscillation to nominal vertical acceleration and applies this nominal acceleration effect as a correction to measured vertical acceleration. 15. The laundry machine as claimed in claim 14, wherein the controller uses corrected vertical accelerations to correct the derived components. 16. The laundry machine as claimed in claim 12, wherein the controller corrects derived components for the accelerations using a mass term that adjusts for the contribution of an acceleration applied at one support location to the derived force component at the other support location. 17. A laundry machine comprising: a drum supported at at least two spaced apart support locations on a single support shaft for rotation about a rotation axis,sensors collectively providing: output from which a force component of a supporting force on parallel axes at the two spaced apart support locations can be derived,output from which an acceleration component of acceleration of the two spaced apart support locations on the parallel axes can be derived,output from which angular velocity of said drum rotation axis can be derived, the derived angular velocity being about an axis perpendicular to the drum rotation axis, parallel to the axes of the force component and through the centre of mass of the drum and any held laundry load, wherein the sensor output from which the angular velocity is derived results from motion of the support locations perpendicular to the drum rotation axis,output from which a mass of the rotating drum and/or laundry load, and the axial location along the drum rotation axis of the centre of mass of the drum and/or laundry load, can be continuously derived,a balance correction system able to apply a variable amount of a balance correction mass at a selectable angular location of the drum at at least two spaced apart locations along the drum rotation axis, anda controller receiving outputs of the sensors, and programmed to continuously calculate balance corrections to apply, the calculation accounting for flexing of the single support shaft. 18. The laundry machine as claimed in claim 17, wherein the calculation estimates a force induced by additional centrifugal forces from angular displacement of the drum's principle axis away from the drum rotation axis due to shaft flexing. 19. The laundry machine as claimed in claim 17, wherein the calculation uses a stored value for stiffness of the support shaft and drum.