Multi-link spherical joint with collocated centers of rotation

A spherical joint, comprising:

• a shell that is hollow and at least partially spherical, wherein the shell includes a first shell section and a second shell section that are configured to be coupled together, wherein the shell also includes a plurality of shell rail sections including a first shell rail section, wherein the first shell rail section includes:
• a portion of an outer surface of the shell;
• a portion of an inner surface of the shell;
• and
• a first opening edge section that defines a first shell opening;
• a plurality of rotatable members including a first rotatable member, the first rotatable member including:
• a first outer cup positioned at least partially outside of the shell and having an outer track surface, wherein the outer track surface is at least partially spherical and comprises a radius that is substantially the same as a radius of the outer surface of the shell;
• and
• a first inner cup positioned at least partially inside of the shell and having an inner track surface, wherein the inner track surface is at least partially spherical and comprises a radius that is substantially the same as a radius of the inner surface of the shell, and wherein a diameter of the first inner cup is greater than a diameter of the first shell opening such that the first inner cup is configured to be inserted into an interior of the shell prior to the first and second shell sections being coupled together;
• a first cup connector portion extending through the first shell opening and coupling the first outer cup and the first inner cup together;
• and
• a first rotatable member connector portion configured to couple the first rotatable member to an elongated member;
• wherein the first shell rail section is positioned at least partially between the outer and inner track surfaces;
• and
• wherein the first rotatable member is configured to move along a first arcuate path with respect to the shell while a central longitudinal axis through the first rotatable member remains extending through a center of the shell.

A truss structure, comprising:

• a plurality of joints including a first joint, wherein each joint comprises:
• a shell that is hollow and at least partially spherical, wherein the shell includes a plurality of shell rail sections including a first shell rail section and a second rail section, wherein the first and second shell rail sections each include:
• a portion of an outer surface of the shell;
• a portion of an inner surface of the shell;
• and
• an opening edge section that defines a shell opening;
• a plurality of rotatable members including a first rotatable member and a second rotatable member, wherein the first rotatable member is configured to move along a first arcuate path with respect to the shell while a central longitudinal axis through the first rotatable member remains extending through a center of the shell, wherein the second rotatable member is configured to move along a second arcuate path with respect to the shell while a central longitudinal axis through the second rotatable member remains extending through the center of the shell, and wherein the first and second rotatable members each include:
• an outer cup positioned at least partially outside of the shell and having an outer track surface;
• and
• an inner cup positioned at least partially inside of the shell and having an inner track surface, wherein the first shell rail section is positioned at least partially between the outer and inner track surfaces of the first rotatable member, and wherein the second shell rail section is positioned at least partially between the outer and inner track surfaces of the second rotatable member;
• a plurality of actuators including a first actuator and a second actuator;
• wherein the first actuator is coupled to the outer cup of the first rotatable member of the first joint, wherein the first actuator is configured to extend and retract, wherein the first rotatable member of the first joint and the first actuator are configured to move with respect to the shell of the first joint while the central longitudinal axis through first rotatable member of the first joint and the first actuator remains extending through the center of the shell of the first joint;
• wherein the second actuator is coupled to the outer cup of the second rotatable member of the first joint, wherein the second actuator is configured to extend and retract, wherein the second rotatable member of the first joint and the second actuator are configured to move with respect to the shell of the first joint while the central longitudinal axis through second rotatable member of the first joint and the second actuator remains extending through the center of the shell of the first joint.