Surgical table base with high stiffness and adjustable support members with force feedback

1. A base for a surgical table, comprising:

a base body having an upper side that is arranged to support a surgical table, any equipment carried by the surgical table, and a patient on the surgical table, which collectively represents a table load that is carried by the base body to support the surgical table on a surface;

a support assembly coupled to a lower side of the base body to support the base body on the surface, the support assembly including four support members that are spaced about the base body and form a rectangular region below the base body,

wherein each support member 1) is disposed at a different corner of the rectangular region, 2) has an end coupled to the lower side of the base body and a surface-engaging end, 3) is configured to transmit a portion of a total load represented by the weight of the base and the table load through the surface-engaging end to the surface, and 4) maintains a fixed vertical orientation with respect to a vertical axis of the base,

wherein three support members of the four support members are non-adjustable relative to the base body, and surface-engaging ends of the three support members are in contact with the surface, thereby defining a plane along the surface,

wherein a fourth support member of the four support members comprising a fixed portion that has the end coupled to the lower side of the base body and a movable portion that is slidably coupled to the fixed portion and has the surface-engaging end, the fourth support member being adjustable to 1) slide the movable portion along the vertical axis to move the surface-engaging end of the movable portion in a vertical direction and 2) come into contact with a portion of the surface while the surface-engaging ends of the three support members are in contact with the surface, thereby redistributing the total load between the four support members;

a load sensor operably coupled to the support assembly and disposed to detect the portion of the total load carried by at least one of the three non-adjustable support members;

a position sensor that is coupled to the fourth support member to sense a position of the movable portion with respect to the fixed portion; and

a controller configured to

determine an available range of motion of the fourth support member for moving the surface-engaging end based on the position of the movable portion;

receive a signal from the load sensor indicative of the portion of the total load carried by the at least one of three non-adjustable support members,

upon a determination that 1) the portion of the total load is not within an acceptable range and 2) the available range of motion exceeds a threshold, cause the fourth support member to move the surface-engaging end of the movable portion to change the portion of the total load carried by the at least one of the three non-adjustable support members.

2. The base of claim 1 , wherein at least one of the support members includes a wheel to support the base for movement on the surface.

3. The base of claim 2 , wherein the fourth support member includes the wheel.

4. The base of claim 1 , wherein the fixed portion is a first fixed portion and the movable portion is a first movable portion, wherein the support assembly includes a fifth support member that is adjustable in the vertical direction, the fifth support member comprising:

a second fixed portion that is coupled to the lower side of the base body;

a second movable portion that is slidably coupled to the fixed portion; and

a wheel that is coupled to a distal end of the second movable portion, wherein the wheel is configured to support the base for movement on the surface,

wherein the fifth support member is disposed within the rectangular region and is off-center.

5. The base of claim 1 , wherein the four support members are a first plurality of support members, wherein the support assembly further comprises a second plurality of support members that are separate from the first plurality of support members and that are each adjustable in the vertical direction, wherein each support member of the second plurality of support members comprises a wheel, wherein the second plurality of support members are configured to support the base for movement on the surface.

6. The base of claim 5 , wherein the second plurality of support members are movable vertically to change the base from a first, movable configuration in which the base is supported only on the wheels of the second plurality of support members and is movable relative to the surface on the wheels, and a second, fixed configuration in which the base is supported by the first plurality of support members and is fixed relative the surface.

7. The base of claim 4 , wherein the wheel is a first wheel, wherein the at least one of the three support members comprises a second wheel, wherein the fifth support member is movable vertically to change the base from a first, movable configuration in which the fifth support member is in a vertically extended position such that the base is supported only on the first and second wheels and is movable relative to the surface, and a second, fixed configuration in which the fifth support member is in a vertically retracted position such that the base is supported by the four support members and is fixed relative to the surface.

8. The base of claim 1 , wherein the controller is configured to, upon the determination that the portion of the total load is not within the acceptable range, send a signal to alert a user that the four support members are not balancing the total load to support the surgical table.

9. The base of claim 1 , further comprising an actuator coupled to the fourth support member and operable to move the surface-engaging end of the movable portion of the fourth support member.

10. The base of claim 9 , wherein the actuator includes a motor.

11. The base of claim 10 , wherein the controller is configured to cause the fourth support member to move by sending a signal to the motor to cause the motor to move the surface-engaging end of the movable portion to change the portion of the total load carried by the at least one of the three non-adjustable support members.

12. The base of claim 11 , wherein the signal from the load sensor is a first load sensor signal and the signal to the motor is a first motor signal, the controller being further operable to:

receive a second signal from the load sensor indicative of the portion of the total load carried by the at least one of the three non-adjustable support members;

determine whether the portion of the total load is not outside of the acceptable range; and

if the portion of the total load is not outside of the acceptable range, send a second signal to the motor to cause the motor to stop moving the surface-engaging end of the movable portion.

13. A method performed by a programmed processor for stabilizing a surgical table on a surface, the surgical table having a base including a support assembly having four support members spaced about the base and forming a rectangular region below the base, each support member 1) being disposed at a different corner of the rectangular region, 2) having an end coupled to a lower side of the base and a surface-engaging end, 3) being configured to transmit a portion of a total load of the surgical table through the surface-engaging end to the surface, and 4) maintaining a fixed vertical orientation with respect to a vertical axis of the base, three support members of the four support members being non-adjustable relative to the base, and a fourth support member of the four support members comprising a fixed portion that has the end coupled to the lower side of the base and a movable portion that is slidably coupled to the fixed portion and has the surface-engaging end, the fourth support member being adjustable to slide the movable portion along the vertical axis to move the surface-engaging end of the movable portion in a vertical direction, the base having a load sensor disposed to detect the portion of the total load carried by one of the support members, and the method comprising:

while surface-engaging ends of the three support members are in contact with the surface, thereby defining a plane along the surface, receiving a first signal from the load sensor indicative of the portion of the total load carried by the one of the three support members;

receiving a second signal from a position sensor that is coupled to the fourth support member, the second signal from the position sensor indicating a position of the movable portion with respect to the fixed portion;

determining an available range of motion of the fourth support member for moving the surface-engaging end based on the position of the movable portion; and

upon a determination that 1) the portion of the total load is not within an acceptable range and 2) the available range of motion exceeds a threshold, causing the fourth support member to

move the surface-engaging end of the movable portion relative to the plane, and

come into contact with a portion of the surface while the surface-engaging ends of the three support members are in contact with the surface, thereby redistributing the total load between the four support members.

14. The method of claim 13 , wherein the surgical table includes a motor coupled to the fourth support member and operable to move the surface-engaging end of the movable portion, wherein the causing the surface-engaging end of the movable portion to move includes sending a motor signal to the motor to move the surface-engaging end.

15. The method of claim 13 , wherein the signal to the motor is a first motor signal, further comprising:

receiving a second signal from the load sensor indicative of the portion of the total load carried by the one of the three support members;

determining whether the portion of the total load is not outside of the acceptable range; and if the portion of the total load is not outside of the acceptable range, sending a second motor signal to the motor to cause the motor to stop moving the surface-engaging end of the movable portion.

16. A base for a surgical table, comprising:

a base body having an upper side that is arranged to support a surgical table, any equipment carried by the surgical table, and a patient on the surgical table, which collectively represent a table load to be carried by the base body to support the surgical table on a surface;

a support assembly coupled to a lower side of the base body to support the base body on the surface, the support assembly including four support members that are spaced about the base body and form a rectangular region below the base body,

wherein each support member 1) is disposed at a different corner of the rectangular region, 2) has an end coupled to the lower side of the base body and a surface-engaging end, 3) is configured to transmit a portion of a total load represented by the weight of the base and the table load through the surface-engaging end to the surface, and 4) maintains a fixed vertical orientation with respect to a vertical axis of the base,

wherein three support members of the four support members are non-adjustable relative to the base body and surface-engaging ends of the three support members are in contact with the surface, thereby defining a plane along the surface,

wherein a fourth support member of the four support members comprising a fixed portion that has the end coupled to the lower side of the base body and a movable portion that is slidably coupled to the fixed portion and has the surface-engaging end, the fourth support member being adjustable to 1) slide the movable portion along the vertical axis to move the surface-engaging end of the movable portion in a vertical direction and 2) come into contact with a portion of the surface while the surface-engaging ends of the three support members are in contact with the surface, thereby redistributing the total load between the four support members;

at least four load sensors operably coupled to the support assembly, each load sensor disposed to detect the portion of the total load carried by a respective one of the support members;

a position sensor that is coupled to the fourth support member to sense a position of the movable portion with respect to the fixed portion; and

a controller operable to: receive a signal from each of the load sensors indicative of the portion of the total load carried by the respective one of the support members,

determine a center of gravity for the surgical table based on the signal from each of the load sensors,

determine an available range of motion of the fourth support member for moving the surface-engaging end based on the position of the movable portion, and upon a determination that 1) the center of gravity is not located within an acceptable location and 2) the available range of motion exceeds a threshold, cause the fourth support member to move the surface-engaging end of the movable portion to change the location of the center of gravity to be within the acceptable location.

17. The base of claim 16 , wherein the acceptable location is based on a boundary defined at least in part by at least one of the support members or the base body.

18. The base of claim 16 , wherein the acceptable location is based on a distance from a central axis of the surgical table.