Couch top pitch and roll motion by linear wedge kinematic and universal pivot

A couch top for positioning a patient, comprising:

• a base, comprising;
• a top side;
• and
• one or more first rails mounted on the top side parallel to a Y axis;
• a top, comprising:
• a bottom side;
• and
• one or more second rails mounted to the bottom side parallel to an X axis
• a universal joint coupled between the top and the base so the top is rotatable about the X and the Y axes, the universal joint comprising a cross shaft with a pitch shaft and a roll shaft;
• a first primary encoder on one end of the pitch shaft;
• a first secondary encoder on another end of the pitch shaft;
• a second primary encoder on one end of the roll shaft;
• a second secondary encoder on another end of the roll shaft;
• first and second actuators mounted on the base, the first and the second actuators being coupled to the top on different sides of the Y axis, each of the first and the second actuators comprising:
• a motor;
• a resolver on the motor;
• a screw drive, comprising:
• a spindle shaft coupled to the motor;
• and
• a wedge link comprising or being attached to a nut on the spindle shaft;
• a wedge assembly, comprising:
• a first carriage coupled to the wedge link, the first carriage comprising one or more first linear bearings riding on the one or more first rails on the base, the first carriage comprising one or more inclined rails parallel to the Y axis;
• a second carriage comprising one or more second linear bearings riding on the one or more inclined rails;
• a third carriage comprising one or more third linear bearings engaging the one or more second rails on the bottom side of the top, the third carriage comprising a spherical bushing;
• and
• a fastener securing the third carriage through the spherical bushing to the second carriage;
• a communication interface;
• a power amplifier coupled to motors of the first and the second actuators;
• an input/output (I/O) interface coupled to the first, the second, the third, and the fourth encoders and the resolvers;
• and
• a controller coupled to the communication interface, the power amplifier, and the I/O interface.

An assembly, comprising:

• a first structural element;
• a second structural element;
• a joint means coupled between the first structural element and the second structural element so one structural element is rotatable about first and second horizontal axes relative to the other structural element;
• and
• first and second actuating means coupled between the first and the second structural elements, wherein each of the first and the second actuating means provides precise control by converting multiple rotations to a horizontal displacement and the horizontal displacement to a vertical displacement smaller than the horizontal displacement.