Spherical surface link mechanism, spherical surface link actuating device, link actuating device, and origin positioning method

A link actuating device comprising:

• a spherical surface link mechanism;
• a light source;
• and
• a detector that receives light emitted from the light source, wherein
• the spherical surface link mechanism includes a proximal end link hub, a distal end link hub, a plurality of links, and a plurality of intermediate link hubs,
• each of the plurality of links includes a first end link member, a second end link member, and an intermediate link member,
• the first end link member is coupled, at one end of the first end link member, to the proximal end link hub to be rotatable about a first axis,
• the second end link member is coupled, at one end of the second end link member, to the distal end link hub to be rotatable about a second rotation axis,
• the intermediate link member is coupled, at one end of the intermediate link member, to another end of the first end link member to be rotatable about a third rotation axis and is coupled, at another end of the intermediate link member, to another end of the second end link member to be rotatable about a fourth rotation axis,
• a first center axis, which is a center axis of the proximal end link hub, the first rotation axis, and the third rotation axis cross at a first spherical surface link center point,
• a second center axis, which is a center axis of the distal end link hub, the second rotation axis, and the fourth rotation axis cross at a second spherical surface link center point,
• each of the plurality of intermediate link hubs is connected to the intermediate link member of each of the plurality of links,
• the plurality of intermediate link hubs are coupled to one another to be rotatable about a fifth rotation axis that passes the first spherical surface link center point and the second spherical surface link center point,
• each of the plurality of intermediate link hubs includes a coupling section and a beam section,
• the beam section is connected, at one end of the beam section, to the coupling section and connected, at another end of the beam section, to the intermediate link member,
• a second through-hole piercing through the coupling section in a direction of the fifth rotation axis is formed in a position deviating from a center of the coupling section,
• the second through-holes of the coupling sections of the plurality of intermediate link hubs overlap one another when the distal end link hub is present in an origin position and the coupling sections of the plurality of intermediate link hubs are coupled to one another to be mutually rotatable about the fifth rotation axis,
• a third through-hole piercing through the proximal end link hub in a direction of the first center axis is formed in the proximal end link hub,
• a fourth through-hole piercing through the distal end link hub in a direction of the second center axis is formed in the distal end link hub,
• the second through-hole, the third through-hole, and the fourth through-hole of each of the plurality of intermediate link hubs are present in positions where the second through-hole, the third through-hole, and the fourth through-hole overlap one another when the distal end link hub is present in the origin position, and
• the light is received by the detector passing through the second through-hole, the third through-hole, and the fourth through-hole of each of the plurality of intermediate link hubs when the distal end link hub is present in the origin position.

An origin positioning method comprising preparing a link actuating device including a spherical surface link mechanism, an origin positioning member, and a driving source, wherein

• the spherical surface link mechanism includes a proximal end link hub, a distal end link hub, a plurality of links, and a plurality of intermediate link hubs,
• each of the plurality of links includes a first end link member, a second end link member, and an intermediate link member,
• the first end link member is coupled, at one end of the first end link member, to the proximal end link hub to be rotatable about a first axis,
• the second end link member is coupled, at one end of the second end link member, to the distal end link hub to be rotatable about a second rotation axis,
• the intermediate link member is coupled, at one end of the intermediate link member, to another end of the first end link member to be rotatable about a third rotation axis and is coupled, at another end of the intermediate link member, to another end of the second end link member to be rotatable about a fourth rotation axis,
• a first center axis, which is a center axis of the proximal end link hub, the first rotation axis, and the third rotation axis cross at a first spherical surface link center point,
• a second center axis, which is a center axis of the distal end link hub, the second rotation axis, and the fourth rotation axis cross at a second spherical surface link center point,
• each of the plurality of intermediate link hubs is connected to the intermediate link member of each of the plurality of links, and
• the plurality of intermediate link hubs are coupled to one another to be rotatable about a fifth rotation axis that passes the first spherical surface link center point and the second spherical surface link center point, and
• the origin positioning method further comprises:
• disabling, with the origin positioning member, two or more of the plurality of intermediate link hubs to mutually rotate about the fifth rotation axis when the distal end link hub is present in an origin position;
• applying, with the driving source, preload on each of the plurality of links;
• and
• in a state in which the preload is applied on the plurality of links, outputting or recording at least any one of a position of each of the plurality of links, torque applied to each of the plurality of links from the driving source, and an operation amount of the driving source.