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

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.

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.