Patent Description:
Mechanisms comprising a six-bar arrangement with two sets of intermeshing gears have been utilized to support horizontal or vertical loads for applications such as scissor jacks. These mechanisms have been limited to supporting linear motion. Other mechanisms, especially in the field of exoskeletons and robotics, require at least one degree of rotational freedom with a remote center so that the hardware can work around an object while maintaining an axis passing through that object. Spherical mechanisms are a common solution to this problem, utilizing curved segments rotating along axes that coincide about a single remote center of motion. These mechanisms, if passive, have been configured as <NUM>-bar scissors type segments that form the sides of a parallelogram or rhombus and move along the surface of a sphere originating at the common remote center of motion. An example of these mechanisms is given in <CIT>. At each end of the curved segment assembly, a revolute joint rotates orthogonally to the remote axis to create <NUM>nd and <NUM>rd degrees of freedom coinciding with the remote center of motion. If only a single degree of freedom about the remote axis is required or if a load is to be supported, the proximal and distal revolute joints of the parallelogram must be constrained to keep the mechanism from collapsing. This is done either by actuated means or by a motion controlling mechanism that adds additional segments and a prismatic joint to the assembly. It would be beneficial to have a remote center mechanism capable of rotational motion that can support applied loads about the remote axis without the added complexities inherent in the prior art.

Accordingly, the present disclosure provides a remote center mechanism as defined in appended claim <NUM>.

The present disclosure is directed to a remote center mechanism configured to create one degree of freedom between a base segment and a terminal segment while passively supporting an applied load. The mechanism utilizes six segments (vs four) in a hexagonal shape whose joints coincide at two remote centers of motion (vs 1RCM) to create a remote rotational axis (vs remote point). The mechanism thus rotates about an imaginary cylindrical shell rather than a spherical one. Instead of all the segments being curved, both the base segment and the terminal segment are planar and are coupled to a set of segments along parallel rotational axes that do not intersect. At both the base segment and the terminal segment, each set of segments are geared together in order to constrain the mechanism to one degree of freedom and resist applied loads. A primary embodiment of this mechanism is used in a shoulder supporting exoskeleton to create passive horizontal motion about the shoulder joint. Throughout its range of motion, the mechanism minimizes the profile of the device while transferring the loads from a torque generator located alongside the arm to a torso frame.

More specifically, the remote-center joint comprises a base segment, a terminal segment coupled, a first segment and a third segment each rotatably coupled to the base segment about parallel axes, wherein the first segment and the third segment are geared together, a second segment and a fourth segment each rotatably coupled to the terminal segment about parallel axes, wherein the second segment and the fourth segment are geared together, wherein the second segment is rotatably coupled to the first segment and the third segment is rotatably coupled to the fourth segment such that the terminal segment is rotatable relative to the base segment about an imaginary axis that does not pass through any mechanical joint of the remote-center joint. When the imaginary axis is parallel to a gravity line, the remote center joint transfers a weight of or attached to the terminal segment to the base segment without affecting motion of the terminal segment relative to the base segment about the imaginary axis. When a force or torque is applied to the terminal segment, reaction forces that do not apply a moment about the imaginary axis are transferred from the terminal link through the remote center joint to the base link without causing relative motion of the base link relative to the terminal link about the imaginary axis.

In another embodiment, a remote-center joint for an arm supporting exoskeleton comprises a base segment coupled to a torso frame of the arm supporting exoskeleton, wherein the torso frame is configured to be coupled to a torso of a person, a terminal segment coupled to an arm segment of the arm supporting exoskeleton, wherein the arm segment is configured to be coupled to an arm of the person, a first segment rotatably coupled to the base segment along a first axis, a second segment rotatably coupled to the first segment about a second axis, and rotatably coupled to the terminal segment about a third axis, wherein the first axis, second axis, and third axis intersect at a first point, a third segment rotatably coupled to the base segment along a fourth axis parallel to the first axis, wherein the third segment and the first segment are provided with intermeshing gears, and a fourth segment rotatably coupled to the third segment along a fifth axis, and rotatably coupled to the terminal segment along a sixth axis parallel to the third axis, wherein the fourth axis, fifth axis, and sixth axis intersects at a second point, and wherein the fourth segment and the second segment are provided with intermeshing gears, wherein the remote center joint rotates the arm segment relative to the torso frame about an imaginary axis connecting the first point and the second point crosses approximately through a shoulder joint of the person.

In a similar embodiment, a remote-center joint for an arm supporting exoskeleton comprises a base segment coupled to a torso frame of the arm supporting exoskeleton, wherein the torso frame is configured to be coupled to the torso of a person, a terminal segment coupled to an arm segment of the arm supporting exoskeleton, wherein the arm segment is configured to be coupled to the arm of a person, a first segment and a third segment each rotatably coupled to the base segment about parallel axes, wherein the first segment and the third segment are geared together, a second segment and a fourth segment each rotatably coupled to the terminal segment about parallel axes, wherein the second segment and the fourth segment are geared together, wherein the second segment is rotatably coupled to the first segment and the third segment is rotatably coupled to the fourth segment such that the remote center joint rotates arm segment relative to the torso frame about an imaginary axis that does not pass through any mechanical joint.

<FIG> shows a perspective view of remote center joint <NUM> in a partially extended position. Remote center joint <NUM> is configured to rotate terminal segment <NUM> relative to base segment <NUM> along imaginary axis <NUM>. Remote center joint <NUM> comprises first segment <NUM> rotatably coupled to base segment <NUM> along first axis <NUM>. Second segment <NUM> is rotatably coupled to first segment <NUM> about second axis <NUM> which intersects first axis <NUM> at first point <NUM>. Second segment <NUM> is rotatably coupled to terminal segment <NUM> about third axis <NUM> which intersects first point <NUM>. Third segment <NUM> is rotatably coupled to base segment <NUM> about fourth axis <NUM> parallel to first axis <NUM>. Fourth segment <NUM> is rotatably coupled to third segment <NUM> about fifth axis <NUM> which intersects fourth axis <NUM> at second point <NUM>. Fourth segment <NUM> is rotatably coupled to terminal segment <NUM> along sixth axis <NUM> which intersects second point <NUM>. Imaginary axis <NUM> of rotation of terminal segment <NUM> relative to base segment <NUM> is a line connecting first point <NUM> and second point <NUM>. Third segment <NUM> is geared to first segment <NUM> and fourth segment <NUM> is geared to second segment At least a portion of a weight, force, or torque applied to terminal segment <NUM> is transferred by remote center joint <NUM> to base segment <NUM>.

<FIG> shows a side view of remote center joint <NUM>. It can be seen that imaginary axis <NUM> is substantially separated from the hardware profile and does not interest any segment of remote center joint. In other embodiments, imaginary axis <NUM> does not pass through any mechanical joint. This is in opposition to a real axis which is formed by two or more links and crosses through the hardware of those links, such as first axis <NUM> formed between base segment <NUM> and first segment <NUM>. This allows for remote center joint <NUM> to be placed outside of an object while rotating along an axis that passes through that object. Additionally, remote center joint <NUM> creates imaginary axis <NUM> through only rotational joints, as opposed to creating an axis through a curved track and carriage. Rotational joints are simpler to add bearing surface to and seal, increasing the robustness of remote center joint. Additionally, the collapsed configuration of remote center joint as seen in <FIG> is much smaller than what would be possible with a curved track and carriage.

<FIG> and <FIG> show a top view of remote center joint <NUM>. In this view, first point <NUM> is coincident with second point <NUM> and imaginary axis <NUM> is perpendicular to the page. In the view of <FIG> and <FIG>, first axis <NUM> overlaps and hides fourth axis <NUM>, second axis <NUM> overlaps and hides fifth axis <NUM>, and third axis <NUM> overlaps and hides sixth axis <NUM>. It can be seen that first point <NUM>, and thus imaginary axis <NUM> is substantially separated from the hardware profile. This allows for remote center joint <NUM> to be placed to the side of an object while rotating along an axis that passes through that object.

In <FIG> remote center joint <NUM> is in a flexed position, forming a small joint rotation angle <NUM> between first axis <NUM> and third axis <NUM> about first point <NUM>. Joint rotation angle <NUM> may similarly be defined as the angle between base segment <NUM> and terminal segment <NUM> about first point <NUM>. A collapsing motion is defined as motion of terminal segment <NUM> relative to base segment <NUM> that results in a reduction of joint rotation angle <NUM>. An extension motion is defined as motion of terminal segment <NUM> relative to base segment <NUM> that results in an increase of joint rotation angle <NUM>.

In <FIG> remote center joint <NUM> is in an extend position, forming a large joint rotation angle <NUM> compared to <FIG>. In <FIG> it can be seen how remote center joint <NUM> is capable of moving around an object while maintaining imaginary axis <NUM> passing through the object. It can be seen that terminal segment <NUM> rotates relative to base segment <NUM> through the intermediate segments and axes without terminal segment <NUM> being directly coupled to base segment <NUM>. Rotation of terminal segment <NUM> about imaginary axis <NUM> is not generated by a single joint, but instead is generated by the collective six joints forming first axis <NUM>, second axis <NUM>, third axis <NUM>, fourth axis <NUM>, fifth axis <NUM>, and sixth axis <NUM>. It can also be appreciated by one skilled in the art that despite the number of segments and axes between terminal segment <NUM> and base segment <NUM>, terminal segment <NUM> has only one degree of freedom and is thus not able to translate or rotate in directions other than about imaginary axis <NUM> due to forces that may be applied to any segment of remote center joint <NUM>. This allows for controlled and predictable motion of terminal segment <NUM> relative to base segment <NUM>.

Passive motion of remote center joint <NUM> may be achieved through forces applied to terminal segment <NUM> about imaginary axis <NUM> while base segment <NUM> remains fixed. Forces applied to terminal segment <NUM> not creating a movement about imaginary axis <NUM> will be transferred to base segment <NUM> without affecting motion of remote center joint <NUM>. In some embodiments, forces from a rotary or linear actuator, either active or passive, may be applied between any two segments of remote center joint <NUM> to control motion between terminal segment <NUM> and base segment <NUM>. The actuator may be mounted directly onto remote center joint <NUM>, or forces from an externally mounted actuator may be transferred to remote center joint <NUM> through a cable or cable and pulley system.

<FIG> shows a top view of first segment <NUM> with first axis <NUM> and second axis <NUM> converging at first point <NUM>. Arc angle <NUM> is defined as the angle between first axis <NUM> and second axis <NUM>. First distance <NUM> is the measure between first point <NUM> and first segment <NUM> along first axis <NUM>. Second distance <NUM> is the measure between first point <NUM> and first segment <NUM> along second axis <NUM>. In some embodiments as shown in <FIG> first distance <NUM> of first segment is different than second distance <NUM> of first segment. In other embodiments not shown, first distance <NUM> of first segment is the same as second distance <NUM> of first segment. First distance <NUM> and second distance <NUM> may be utilized to change the position of first point <NUM> or to alter the profile of remote center joint <NUM>. It may be understood by one stilled in the art that first segment <NUM> may be of any shape to create first axis <NUM> and second axis <NUM>. In <FIG> first segment <NUM> has a single bent profile, however first segment <NUM> may have a curved profile <NUM> as shown in <FIG> or a double bent profile <NUM> as show <FIG>, among many others. Each segment may be of any shape as long as it comprises two intersecting axes of rotation when coupled to neighboring segments. One of skill in the art may also understand that the above description may similarly apply to second segment <NUM>, third segment <NUM>, or fourth segment <NUM>. When applied to other segments, first distance <NUM> corresponds to the distance along first axis <NUM>, third axis <NUM>, fourth axis <NUM> or sixth axis <NUM> connecting to base segment <NUM> or terminal segment <NUM> as applicable. When applied to other segments, second distance <NUM> corresponds to the distance along second axis <NUM> or fifth axis <NUM> as applicable.

In some embodiments of remote center joint <NUM>, arc angle <NUM> of first segment <NUM>, second segment <NUM>, third segment <NUM>, and fourth segment <NUM> defines the range of motion of terminal segment <NUM> relative to base segment <NUM>. In general, the range of motion of remote center joint <NUM> is the lesser of arc angle <NUM> of first segment <NUM> added to arc angle <NUM> of second segment <NUM> compared to arc angle <NUM> of third segment <NUM> added to arc angle <NUM> of fourth segment <NUM>. In a preferred embodiment of remote center joint <NUM>, arc angle <NUM> of first segment <NUM>, second segment <NUM>, third segment <NUM>, and fourth segment <NUM> are equal. This allows the segments of remote center joint <NUM> to move symmetrically as shown in <FIG>, <FIG>, and <FIG>. In other embodiments, arc angle <NUM> of first segment <NUM> is equal to arc angle <NUM> of third segment <NUM> and arc angle <NUM> of second segment <NUM> is equal to arc angle <NUM> of fourth segment <NUM> while the arc angle of first segment <NUM> is not equal to the arc angle of second segment <NUM>. This causes symmetric motion between first segment <NUM> and third segment <NUM>, and symmetric motion between second segment <NUM> and fourth segment <NUM>, but asymmetric motion between first segment <NUM> and second segment <NUM> as shown in <FIG>. In particular, the segments with (reduced) arc angle <NUM> will rotate about base segment <NUM> or terminal segment <NUM> to a greater degree than the segments with (increased) arc angle <NUM>. This changes the profile of remote center joint <NUM> throughout the range of motion of terminal segment <NUM> relative to base segment <NUM>. Still in other embodiments not shown, arc angle <NUM> of first segment <NUM> is equal to arc angle <NUM> of second segment <NUM> and arc angle <NUM> of third segment <NUM> is equal to arc angle <NUM> of fourth segment <NUM> while the arc angle <NUM> of first segment <NUM> is not equal to the arc angle <NUM> of third segment <NUM>. This creates a similar asymmetry as seen in <FIG> but between the first segment <NUM> and second segment <NUM> compared to the third segment <NUM> and fourth segment <NUM>. In some embodiments the arc angle <NUM> is different between each of the first segment <NUM>, second segment <NUM>, third segment <NUM>, and fourth segment <NUM> creating asymmetry of motion between each segment. One of skill in the art may understand that changing the arc angle <NUM> of various segments may be used to alter the profile, strength, or aesthetic look of remote center joint <NUM>.

In some embodiments of remote center joint <NUM>, first distance <NUM> and second distance <NUM> of first segment <NUM>, second segment <NUM>, third segment <NUM>, and fourth segment <NUM> defines the distance of imaginary axis <NUM> from the hardware, the orientation of imaginary axis <NUM>, and the profile of remote center joint <NUM>.

In a preferred embodiments of remote center joint <NUM>, first distance <NUM> and second distance <NUM> of first segment <NUM> is equal to first distance <NUM> and second distance <NUM> of third segment <NUM> and first distance <NUM> and second distance <NUM> of second segment <NUM> is equal to first distance <NUM> and second distance <NUM> of fourth segment <NUM>. This creates symmetric motion between first segment <NUM> and third segment <NUM> and creates imaginary axis <NUM> that is perpendicular to first axis <NUM>, third axis <NUM>, fourth axis <NUM>, and sixth axis <NUM> as shown in <FIG>.

In another embodiment of remote center joint <NUM>, first distance <NUM> of first segment <NUM> is different than first distance <NUM> of third segment <NUM> and first distance <NUM> of second segment <NUM> is different than first distance <NUM> of fourth segment <NUM>. This effect, not shown, tilts imaginary axis <NUM> such that it is not perpendicular to first axis <NUM>, third axis <NUM>, fourth axis <NUM>, and sixth axis <NUM>. In another embodiment of remote center joint <NUM>, second distance <NUM> of first segment <NUM> is different than second distance <NUM> of third segment <NUM> and second distance <NUM> of second segment <NUM> is different than second distance <NUM> of fourth segment <NUM>. This effect, not shown, creates an asymmetry in profile between the first segment <NUM> and second segment <NUM> compared to the third segment <NUM> and fourth segment <NUM>.

In some embodiments, first distance <NUM> and second distance <NUM> of first segment <NUM> is the same as first distance <NUM> and second distance <NUM> of second segment <NUM>, and first distance <NUM> and second distance <NUM> of third segment <NUM> is the same as first distance <NUM> and second distance <NUM> of fourth segment <NUM>. This configuration is shown in <FIG>, <FIG> and <FIG> such that first segment <NUM> and second segment <NUM> may be joined by a double supported clevis joint. In addition, terminal segment <NUM> will contact base segment <NUM> in a fully flexed position as the segments are not configured to overlap.

In another embodiment, first distance <NUM> and second distance <NUM> of first segment <NUM> is different than first distance <NUM> and second distance <NUM> of second segment <NUM>, and first distance <NUM> and second distance <NUM> of third segment <NUM> is different than first distance <NUM> and second distance <NUM> of fourth segment <NUM>. This configuration is shown in <FIG> and <FIG> such that first segment <NUM> and second segment <NUM> may overlap each other. As a result, terminal segment <NUM> will not contact base segment <NUM> in a fully flexed position to increase the range of motion of remote center joint <NUM> so that it may move bidirectionally. Altering the first distance <NUM> of any segment will affect how far base segment <NUM> overlaps terminal segment <NUM> at the fully flexed position, and altering the second distance <NUM> of any segment will affect the overlap between segments, specifically the overlap between first segment <NUM> and second segment <NUM> along second axis <NUM>, or the overlap between third segment <NUM> and fourth segment <NUM> along fifth axis <NUM>. Each segment may have varying the first distance <NUM> or second distance <NUM> depending on the mechanical connection in order to align their respective axes to first point <NUM> or second point <NUM>.

In some embodiments, first distance <NUM> and second distance <NUM> of the first segment <NUM>, second segment <NUM>, third segment <NUM>, and fourth segment <NUM> are defined such that imaginary axis <NUM> is perpendicular to the first axis <NUM>.

In some embodiments the gearing between first segment <NUM> and third segment <NUM> is a <NUM>:<NUM> ratio. In other embodiments the gearing between second segment <NUM> and fourth segment <NUM> is a <NUM>:<NUM> ratio. In the primary embodiment the gearing between segments occurs through gear teeth integrated into each segment. In other embodiments, separate gears may be attached to each segment to accomplish controlled geared motion between segments. Still in other embodiments, a high friction coating may be sufficient to gear two segments together.

In some embodiments, two segments of remote center joint <NUM> may be configured to hard stop against each other to limit the range of motion of terminal segment <NUM> relative to base segment <NUM>. Hard stopping motion of remote center joint <NUM> at an extended position may be utilized to limit the range of motion of remote center joint <NUM>, or to prevent remote center joint <NUM> from entering a position after which it becomes difficult to re-collapse the joint. Similarly, hard stopping motion of remote center joint <NUM> at a flexed position may be utilized to limit the range of motion. Remote center joint <NUM> may further comprise a hard stop spring, such as a spring plunger, coupled to any of the segments and configured to selectively contact another segment in order to bias remote center joint <NUM> away from the hard stop position.

<FIG> shows a perspective view of remote center joint <NUM> in a fully extended position where at least one extension hard stop <NUM> limits further extension motion. In this embodiment, as also shown in <FIG> in a more flexed position, both first segment <NUM> and third segment <NUM> include extension hard stop <NUM>. When extension hard stop <NUM> of first segment <NUM> contacts extension hard stop <NUM> of third segment <NUM>, both first segment <NUM> and third segment <NUM> are prevented from further rotation about first axis <NUM> and fourth axis <NUM> respectively, thus preventing further extension motion of terminal segment <NUM> relative to base segment <NUM>. It may be understood by one skilled in the art that hard stops may be placed between any set of two segments to prevent rotation corresponding to collapsing or extending motion of terminal segment <NUM> relative to base segment <NUM>. In some embodiments one of the segments comprises first extension hard stop <NUM> and another of the segments comprises second extension hard stop <NUM>, wherein at a fully extended position, first extension hard stop <NUM> and second extension hard stop <NUM> contact each other to prevent remote center joint <NUM> from increasing joint rotation angle <NUM>.

In a preferred embodiment, remote center joint <NUM> further comprises first magnet <NUM> coupled to first extension hard stop <NUM> and second magnet <NUM> coupled to second extension hard stop <NUM>, wherein first magnet <NUM> and second magnet <NUM> are configured to repel first extension hard stop <NUM> from second extension hard stop <NUM>. In another embodiment, remote center joint <NUM> further comprises first magnet <NUM> coupled to first extension hard stop <NUM> and second magnet <NUM> coupled to second extension hard stop <NUM>, wherein first magnet <NUM> and second magnet <NUM> are configured to attract first extension hard stop <NUM> to second extension hard stop <NUM>. In some embodiments, remote center joint <NUM> further comprises first magnet <NUM> coupled to any of the segments, and second magnet <NUM> coupled to any other segment, wherein first magnet <NUM> and second magnet <NUM> are configured to bias remote center joint away from an extended hard stop position. In other embodiments, first magnet <NUM> and second magnet <NUM> are configured to bias remote center joint <NUM> into an extended hard stop position. In the embodiment of <FIG> and <FIG>, first magnet <NUM> is coupled to first segment <NUM>, and second magnet <NUM> is coupled to third segment <NUM>. First magnet <NUM> and second magnet <NUM> are configured to repel each other to bias the rotation of first segment <NUM> and third segment <NUM> in a direction that corresponds to a reduction in joint rotation angle <NUM> of terminal segment <NUM> relative to base segment <NUM>. In this configuration the force between first magnet <NUM> and second magnet <NUM> is greatest at the fully extended position and reduces as remote center joint <NUM> moves away from this position. One of skill in the art may recognize that a similar result could be obtained through a spring, such as a spring plunger, coupled to first segment <NUM> or third segment <NUM> in a similar location. An opposite result may be achieved by reversing the polarity of either first magnet <NUM> or second magnet <NUM> so that they attract each other, resulting in a bias of remote center joint <NUM> towards the fully extended position. One of skill in the art may also recognize that an equivalent function may be achieved between any two segments of remote center joint <NUM>, with the polarity of first magnet <NUM> and second magnet <NUM> impacting whether remote center joint <NUM> is biased towards or repelled from any position of terminal segment <NUM> relative to base segment <NUM>, most notably for the fully extended and fully flexed positions.

<FIG> shows remote center joint <NUM> in a fully flexed position where at least one flexion hard stop <NUM> prevents further collapsing motion. In this embodiment, as also shown in <FIG> in a more extended position, both first segment <NUM> and terminal segment <NUM> include the at least one flexion hard stop <NUM>. When the at least one flexion hard stop <NUM> of first segment <NUM> contacts the at least one flexion hard stop <NUM> of terminal segment <NUM>, first segment <NUM> is prevented from further rotation about first axis <NUM>, thus preventing further collapsing motion of terminal segment <NUM> relative to base segment <NUM>. It may be understood by one skilled in the art that hard stops may be placed between any set of two segments to prevent rotation corresponding to collapsing or extending motion of terminal segment <NUM> relative to base segment <NUM>. In some embodiments one of the segments comprises a first flexion hard stop <NUM> and another of the segments comprises a second flexion hard stop <NUM>, wherein at a fully flexed position, the first flexion hard stop <NUM> and the second flexion hard stop <NUM> contact each other to prevent remote center joint <NUM> from decreasing joint rotation angle <NUM>.

In a preferred embodiment, remote center joint <NUM> further comprises first magnet <NUM> coupled to first flexion hard stop <NUM> and stow magnet <NUM> coupled to second flexion hard stop <NUM>, wherein first magnet <NUM> and stow magnet <NUM> are configured to attract first flexion hard stop <NUM> to second flexion hard stop <NUM>. In some embodiments, remote center joint <NUM> further comprises first magnet <NUM> coupled to any of the segments, and stow magnet <NUM> coupled to any other segment, wherein first magnet <NUM> and stow magnet <NUM> are configured to bias remote center joint <NUM> into a collapsed hard stop position. Holding remote center joint <NUM> in a flexed position may be utilized to store the mechanism in a low-profile manner when not in use. In some embodiments, first magnet <NUM> is configured to attract stow magnet <NUM> in order to bias and hold remote center joint <NUM> in a flexed position. In some embodiments, remote center joint <NUM> may further comprise stow switch <NUM> configured to move stow magnet <NUM> between a first position and a second position. When stow magnet <NUM> is in the first position it comes into contact with first magnet <NUM> when remote center joint <NUM> is in a fully flexed position, thus applying a force to hold remote center joint <NUM> in a fully flexed position. When stow magnet <NUM> is in the second position it does not come into contact with first magnet <NUM> when remote center joint <NUM> is in a fully flexed position and does not apply a force to hold remote center joint <NUM> against flexion hard stop <NUM>. In the primary embodiment, first magnet <NUM> is coupled to first segment <NUM> and stow magnet <NUM> is moveably coupled to terminal segment <NUM>. It may be understood by one skilled in the art that the first magnet <NUM> and stow magnet <NUM> may be placed between any two segments to accomplish the same function as described above.

In some embodiments, remote center joint <NUM> further comprises a stow mechanism configured to hold remote center joint <NUM> in a collapsed configuration when not in use. Many types of mechanism may be used between any two segments to hold remote center joint <NUM> in place. Examples include hook and latch, male/female connectors, or an over the center toggle mechanism, among others.

In some embodiments, remote center joint <NUM> further comprises a spring <NUM> configured to act between at least two segments to bias the motion of terminal segment <NUM> relative to base segment <NUM>. Spring <NUM> may be selected from a list including torsion spring, compression spring, gas spring, leaf spring, elastic band, or other common resilient element known to those skilled in the art. In some embodiments, spring <NUM> is configured to bias the motion of terminal segment <NUM> relative to base segment <NUM> throughout the range of motion of remote center joint <NUM>. Spring <NUM> may be configured to bias remote center joint <NUM> in an extending or collapsing direction. When spring <NUM> is configured to bias remote center joint <NUM> in a collapsing direction it may fulfill a function similar to the stow mechanism described above. In some embodiments, spring <NUM> is configured to bias terminal segment <NUM> in a collapsing direction relative to base segment <NUM> only at the extreme extended range of motion of remote center joint <NUM>. In other embodiments, spring <NUM> is configured to bias terminal segment <NUM> in an extending direction relative to base segment <NUM> only at the extreme collapsed range of motion of remote center joint <NUM>.

It may be understood by one skilled in the art that each segment may be composed of one or more links. In some embodiments, as shown in <FIG> each segment comprises a single link arranged so that each joint is double supported. In other embodiments, as shown in <FIG>, some segments may comprise two links arranged in parallel so that each joint is double supported. Still in other embodiments, as shown in <FIG>, each segment may comprise a single link arranged so that each joint is single supported. Each arrangement may be utilized for one or more segments to optimize remote center joint <NUM> for strength, range of motion, profile, or other common characteristics.

<FIG> and <FIG> show an embodiment of remote center joint <NUM> wherein the segments are configured so that in the fully collapsed configuration first axis <NUM> and third axis <NUM> become approximately coincident. This allows remote center joint <NUM> to maximize its range of motion and minimize its profile when stowed. In the embodiment of <FIG> and <FIG> first segment <NUM> and third segment <NUM> are comprised of single linkages, while second segment <NUM> and fourth segment <NUM> are comprised of at least two linkages that overlap first segment <NUM> and third segment <NUM> while each joint remains double supported. <FIG> shows remote center joint <NUM> in a fully flexed position and <FIG> shows remote center joint <NUM> in an extended position.

<FIG> shows an embodiment where two of remote center joint <NUM> are connected in series in order to maximize the range of motion of a second terminal segment <NUM> relative to base segment <NUM> or to minimize profile of the mechanism. In this embodiment, remote center joint <NUM> further comprises second base segment <NUM>, fifth segment <NUM>, sixth segment <NUM>, seventh segment <NUM>, eighth segment <NUM>, and second terminal segment <NUM>. Second base segment <NUM> is coupled to terminal segment <NUM>. Fifth segment <NUM> is rotatably coupled to second base segment <NUM> about seventh axis <NUM>. Sixth segment <NUM> is rotatably coupled to fifth segment <NUM> about eighth axis <NUM> that intersects seventh axis <NUM> at third point <NUM>. Second terminal segment <NUM> is rotatably coupled to sixth segment <NUM> about ninth axis <NUM> that intersects third point <NUM>. Seventh segment <NUM> is rotatably coupled to second base segment <NUM> along tenth axis <NUM> that is parallel to seventh axis <NUM> and seventh segment <NUM> is geared to fifth segment <NUM>. Eighth segment <NUM> is rotatably coupled to seventh segment <NUM> along eleventh axis <NUM> that intersects tenth axis <NUM> at fourth point <NUM>. Eighth segment <NUM> is rotatably coupled to second terminal segment <NUM> along twelfth axis <NUM> that intersects fourth point <NUM> and eighth segment <NUM> is geared to sixth segment <NUM>. Second terminal segment <NUM> is configured to rotate relative to second base segment <NUM> about second imaginary axis <NUM> passing between third point <NUM> and fourth point <NUM>. In some embodiments, second segment <NUM> is geared to fifth segment <NUM> in a <NUM>:<NUM> ratio to create symmetrical motion between the first remote center joint <NUM> and the second remote center joint <NUM>. In some embodiments, fourth segment <NUM> is geared to seventh segment <NUM> to create symmetrical motion between first remote center joint <NUM> and second remote center joint <NUM>. One of skill in the art may understand that any number of remote center joint <NUM> may be connected in series in a similar manner to accomplish a given range of motion, loading, profile, or other mechanical requirement. In some embodiments the linkages of the various remote center joint <NUM> connected in series may have varying radius, arc angle, or flat sections to vary the location of the multiple imaginary axes or the relative motion of the various segments.

In some embodiments as shown in <FIG> and <FIG>. , remote center joint <NUM> may be used as part of shoulder supporting exoskeleton <NUM>. Shoulder supporting exoskeleton <NUM> may also be referred to as arm supporting exoskeleton <NUM>. In one embodiment, remote center joint <NUM> is used to provide motion between torso frame <NUM> coupled to person's torso <NUM> and arm segment <NUM> coupled to person's upper arm <NUM>. In some embodiments, arm segment <NUM> is a shoulder supporting actuator configured to at least partially support the gravitational effects due to the weight of the arm about the shoulder joint. In some embodiments, the motion provided by remote center joint <NUM> as a part of shoulder supporting exoskeleton <NUM> corresponds to relatively horizontal motions of upper arm <NUM> of person <NUM> while arm segment <NUM> provides motion for or applies a supportive force to relatively vertical motions of upper arm <NUM> of person <NUM>. When shoulder supporting exoskeleton <NUM> is worn by person <NUM>, imaginary axis <NUM> created by remote center joint <NUM> passes approximately through the shoulder joint of person <NUM> while the hardware remains behind or to the side of the body of person <NUM>. This allows arm segment <NUM> to move relative to torso frame <NUM> about an axis that approximately coincides with the shoulder joint of person <NUM> to provide a natural range of motion and minimize relative motion between shoulder supporting exoskeleton <NUM> and upper arm <NUM> of person <NUM> or torso <NUM> of person <NUM>. Approximately through the shoulder joint of person <NUM> may mean that an axis crosses through the body of the person near the shoulder joint, scapula, or upper arm. Additionally, this configuration allows for all needed hardware to be placed behind or to the side of person <NUM>, without any hardware being located above the shoulder of person <NUM> or next to a head <NUM> of person <NUM>. The passive motion of remote center joint <NUM> is controlled by forces from upper arm <NUM> of person <NUM> being transferred through arm segment <NUM> to terminal segment <NUM> while base segment <NUM> is fixed to torso frame <NUM> which is in turn fixed to torso <NUM> of person <NUM>. Supportive forces and torques that are applied to upper arm <NUM> of person <NUM> from the arm segment <NUM> are transferred through remote center joint <NUM> to torso frame <NUM>, which in turn applies the forces and torques to torso <NUM> of person <NUM> and hips <NUM> of person <NUM>. In some embodiments, multiples of remote center joint <NUM> may be used as part of shoulder supporting exoskeleton <NUM>. In the primary embodiment shoulder supporting exoskeleton <NUM> comprises a torso frame <NUM>, a left remote center joint <NUM> coupled to torso frame <NUM>, a left arm segment <NUM> coupled to left remote center joint <NUM>, a right remote center joint <NUM> coupled to torso frame <NUM>, and right arm segment <NUM> coupled to right remote center joint <NUM>, wherein torso frame <NUM> is configured to be coupled to torso <NUM> of person <NUM>, left arm segment <NUM> is configured to be coupled to upper arm <NUM> of person <NUM> on the left side, and right arm segment <NUM> is configured to be coupled to upper arm <NUM> of person <NUM> on the right side.

<FIG> shows a rear view of remote center joint <NUM> as part of shoulder supporting exoskeleton <NUM>. Remote center joint <NUM> is configured to rotate terminal segment <NUM>, coupled to upper arm <NUM> of person <NUM>, relative to base segment <NUM>, coupled to torso <NUM> of person <NUM>, along imaginary axis <NUM> passing through the body of person <NUM>. Remote center joint <NUM> comprises first segment <NUM> rotatably coupled to base segment <NUM> along first axis <NUM>. Second segment <NUM> is rotatably coupled to first segment <NUM> about second axis <NUM> which intersects first axis <NUM> at first point <NUM>. Second segment <NUM> is rotatably coupled to terminal segment <NUM> about third axis <NUM> which intersects first point <NUM>. Third segment <NUM> is rotatably coupled to base segment <NUM> about fourth axis <NUM> parallel to first axis <NUM>. Third segment <NUM> is geared to the first segment <NUM>. Fourth segment <NUM> is rotatably coupled to third segment <NUM> about fifth axis <NUM> which intersects fourth axis <NUM> at second point <NUM>. Fourth segment <NUM> is rotatably coupled to terminal segment <NUM> along sixth axis <NUM> which intersects second point <NUM>. Fourth segment <NUM> is geared to second segment <NUM>. Imaginary axis <NUM> of rotation of terminal segment <NUM> relative to base segment <NUM> is a line connecting first point <NUM> and second point <NUM>.

In some embodiments, remote center joint <NUM> is configured to provide horizontal shoulder motion for shoulder supporting exoskeleton <NUM> wherein base segment <NUM> is coupled to torso frame <NUM> of shoulder supporting exoskeleton <NUM> and terminal segment <NUM> is coupled to arm segment <NUM> of shoulder supporting exoskeleton <NUM>. When person <NUM> is standing upright, remote center joint <NUM> provides motion along imaginary axis <NUM> substantially parallel to gravity line <NUM>. In this embodiment, when person <NUM> is standing upright, remote center joint <NUM> transfers a weight of the arm segment <NUM> to the torso frame <NUM> without affecting motion of terminal segment <NUM> relative to base segment <NUM>. Similarly, when the person <NUM> is standing upright, remote center joint <NUM> accommodates for a horizontal motion of the upper arm <NUM> of person <NUM> between arm segment <NUM> and torso frame <NUM> when the arm supporting exoskeleton <NUM> is worn by the person <NUM>.

In some embodiments, when person <NUM> is standing upright, as a part of shoulder supporting exoskeleton <NUM> remote center joint <NUM> provides motion along imaginary axis <NUM> skew to gravity line <NUM> to bias the motion of upper arm <NUM> of person <NUM> relative to torso <NUM> of person <NUM>.

In some embodiments, torso frame <NUM> further comprises shoulder straps <NUM> that at least partially encircle a person's s torso <NUM>, and belt <NUM> that at least partially encircles hips <NUM> of person <NUM> to couple shoulder supporting exoskeleton <NUM> to person <NUM>. Remote center joint <NUM> may further comprise anchor strap <NUM> coupled to base segment <NUM> at its first end and configured to couple to shoulder strap <NUM> from its second end. Anchor strap <NUM> may be tightened to better secure remote center joint <NUM> to person <NUM>. In other embodiments, anchor strap <NUM> may be coupled to base segment <NUM> from both ends, and be configured to at least partially encircle persons shoulder, upper arm <NUM> of person <NUM>, or torso <NUM> of person <NUM>.

Torso frame <NUM> may further comprise lower spine <NUM> and upper spine <NUM>. To adjust the position of remote center joint <NUM> relative to belt <NUM>, the location of upper spine <NUM> may be adjusted and held in place relative to lower spine <NUM> along the major axis of lower spine <NUM>. This adjustment may be used to adjust the exoskeletons to persons of different height in order to align support axis <NUM> of arm segment <NUM> with persons shoulder joint. The shoulder joint of person <NUM> may refer to any area around the shoulder including but not limited to the glenohumeral joint, scapula, humerus, and clavicle. In some embodiments, torso frame <NUM> further comprises hip frame <NUM> coupled to both ends of belt <NUM> from its distal sides and to lower spine <NUM> from its center. Hip frame <NUM> may be configured to transfer forces from torso frame <NUM> to hips <NUM> of person <NUM>.

Torso frame <NUM> may further comprise spine mount <NUM> located substantially behind torso <NUM> of person <NUM>. In some embodiments, remote center joint <NUM> is adjustably coupled to spine mount <NUM> along an axis perpendicular to the major axis of upper spine <NUM> or lower spine <NUM>. Remote center joint <NUM> may be moved and fixed in place relative to spine mount <NUM> in order to adjust for the size of person <NUM> to better align imaginary axis <NUM> of rotation with the persons shoulder joint. In other embodiments, remote center joint <NUM> may be rotationally coupled to torso frame <NUM> about an axis substantially parallel to imaginary axis <NUM> created between first point <NUM> and second point <NUM>. This rotational coupling may occur between base segment <NUM> and spine mount <NUM>, or base segment <NUM> may comprise two separate segments capable of rotation relative to each other. A rotational coupling between remote center joint <NUM> and torso frame <NUM> may be used to extend the range of motion of arm segment <NUM> relative to torso frame <NUM>. In other embodiments, remote center joint <NUM> may be prismatically coupled to torso frame <NUM> along a direction perpendicular to imaginary axis <NUM> created between first point <NUM> and second point <NUM>. A prismatic coupling between remote center joint <NUM> and torso frame <NUM> may be used to extend the range of motion of arm segment <NUM> relative to torso frame <NUM> or to dynamically adjust the alignment of imaginary axis <NUM> created between first point <NUM> and second point <NUM> with the shoulder joint of person <NUM>. Still in other embodiments, remote center joint <NUM> may be coupled to torso frame <NUM> with a resilient member configured to deform under load and return to its original position when the load is removed. The resilient member may be configured to increase the range of motion between arm segment <NUM> and torso frame <NUM>. In another embodiment remote center joint <NUM> may be rotationally coupled to arm segment <NUM>. This may occur through a rotational coupling between terminal segment <NUM> and arm segment <NUM>, or terminal segment <NUM> may comprise two independent segments capable of rotating relative to each other. A rotational coupling between remote center joint <NUM> and arm segment <NUM> may be used to extend the range of motion of arm segment <NUM> relative to torso frame <NUM>. It may be understood by one skilled in the art that the rotational couplings between remote center joint <NUM> and torso frame <NUM> or arm segment <NUM> may comprise a spring or magnets to bias motion or hard stops to limit motion as described in regards to the motion of the remote center joint above.

In some embodiments, arm segment <NUM> comprises proximal segment <NUM> coupled to terminal segment <NUM> of remote center joint <NUM>, distal segment <NUM> rotatably coupled to proximal segment <NUM> about support axis <NUM>, and arm brace <NUM> coupled to distal segment <NUM>. In other embodiments, arm segment <NUM> comprises distal segment <NUM> configured to rotate relative to terminal segment <NUM> about support axis <NUM> orthogonal to the imaginary axis <NUM>, wherein the support axis <NUM> crosses approximately through the shoulder joint of the person <NUM>, and torque generator coupled to the distal segment <NUM> configured to apply a torque about the support axis <NUM> such that the distal segment <NUM> applies a force to the person's arm. Still in other embodiments, arm segment <NUM> further comprises proximal segment <NUM> configured to be coupled to terminal segment <NUM>, and distal segment <NUM> configured to rotate relative to proximal segment <NUM> about support axis <NUM> that crosses approximately through the shoulder joint of person <NUM> orthogonal to imaginary axis <NUM>, wherein distal segment <NUM> is configured to attach to the arm of person <NUM>, and torque generator coupled to proximal segment <NUM> from its first end and to distal segment <NUM> from its second end, the torque generator configured to apply a torque about support axis <NUM> such that distal segment <NUM> applies a force to the person's arm to at least partially support the weight of the person's arm.

A torque generator may include a motor, spring, pneumatic, hydraulic or other type of torque or force creating actuator. Torque generator is attached to distal segment <NUM> from its first end and may be attached to terminal segment <NUM> or proximal segment <NUM> from its second end. In other embodiments, torque generator remotely actuates distal segment <NUM> about support axis <NUM> and it attached to distal segment <NUM> from its first end and to any other component of remote center joint <NUM> or torso frame <NUM> from its second end, the forces being transferred to distal segment <NUM> through a Bowden cable or similar device.

In some embodiments, arm segment <NUM> is configured to create a torque between proximal segment <NUM> and distal segment <NUM> about support axis <NUM> in order to at least partially support the weight of upper arm <NUM> of person <NUM>. This torque is applied to upper arm <NUM> of person <NUM> by arm brace <NUM>, and reaction forces and torques are applied to remote center joint <NUM> through proximal segment <NUM>. Remote center joint <NUM> transfers vertical forces from arm segment <NUM> to torso frame <NUM> which is configured to apply the loads to the hips of person <NUM>. Horizontal components of torques from arm segment <NUM> in turn cause terminal segment <NUM> to rotate relative to base segment <NUM> about imaginary axis <NUM>. In some embodiments of remote center joint <NUM>, arm segment <NUM> is configured to apply a torque to arm of person <NUM> about support axis <NUM> orthogonal to imaginary axis <NUM>, wherein reaction forces from the torque that do not create a moment about imaginary axis <NUM> are transferred through remote center joint <NUM> to torso frame <NUM> without affecting motion of terminal segment <NUM> relative to base segment <NUM>.

In some embodiments, support axis <NUM> is orthogonal to imaginary axis <NUM> created between first point <NUM> and second point <NUM>. As upper arm <NUM> of person <NUM> moves horizontally, orthogonal to gravity line <NUM>, remote center joint <NUM> maintains support axis <NUM> passing approximately through persons shoulder joint. In <FIG> and <FIG> a top view and back view of person <NUM> can be seen where persons left arm is oriented to persons side and persons right arm is oriented in front of person <NUM>. It can be seen that when upper arm <NUM> of person <NUM> is oriented to the side of person <NUM>, remote center joint <NUM> moves into a flexed position, as with persons left arm. It can also be seen that when upper arm <NUM> of person <NUM> is oriented in front of person <NUM>, remote center joint <NUM> moves into an extended position, as with persons right arm. Remote center joint <NUM> moves to allow arm segment <NUM> to move in unison with upper arm <NUM> of person <NUM> while torso frame <NUM> remains fixed to torso <NUM> of person <NUM>.

In some embodiments, arm brace <NUM> is adjustably coupled to distal segment <NUM> to adjust the position of arm brace <NUM> relative to support axis <NUM> in order to adjust for the length of upper arm <NUM> of person <NUM>. Arm brace <NUM> may be attached to upper arm <NUM> of person <NUM> through an arm strap. In other embodiments the orientation of proximal segment <NUM> can be adjusted relative to remote center joint <NUM> about an axis parallel to support axis <NUM> to adjust the support provided by arm segment <NUM> to person <NUM>. Still in other embodiments the orientation of proximal segment <NUM> can be adjusted relative to remote center joint <NUM> about an axis orthogonal to imaginary axis <NUM> connecting first point <NUM> and second point <NUM> to adjust the support provided by arm segment <NUM> to person <NUM>. In some embodiments, arm segment <NUM> is rotatably coupled to remote center joint <NUM> about an axis parallel to imaginary axis <NUM> connecting first point <NUM> and second point <NUM> to increase the range of motion of arm segment <NUM> relative to torso frame <NUM>.

In some embodiments, as shown in <FIG> and <FIG>, remote center joint <NUM> may be used as part of neck supporting exoskeleton <NUM>. Neck supporting exoskeleton <NUM> may be used to at least partially support the weight of the head <NUM> of person <NUM> as it moves relative to torso <NUM> of person <NUM>. Neck supporting exoskeleton <NUM> may further comprise torso frame <NUM> coupled to remote center joint <NUM> and configured to couple to torso <NUM> of person <NUM>, and head pillow <NUM> coupled to remote center joint <NUM> and configured to contact the head <NUM> of person <NUM>. In use, remote center joint <NUM> may be configured to create imaginary axis <NUM> between first point <NUM> and second point <NUM> that passes approximately through persons neck. When the head <NUM> of person <NUM> rotates relative to torso <NUM> of person <NUM>, remote center joint <NUM> moves head pillow <NUM> relative to torso frame <NUM> about an axis substantially aligned with persons biological spine to prevent relative motion between head pillow <NUM> and the head <NUM> of person <NUM> to reduce discomfort due to chafing. In <FIG> it can be seen that person's head <NUM> is rotated backwards relative to torso <NUM> of person <NUM>, as if person <NUM> was looking upwards, forcing remote center joint <NUM> into a flexed position. Here, imaginary axis <NUM> between first point <NUM> and second point <NUM> passes through persons neck. In <FIG> it can be seen that person's head <NUM> is rotated forwards relative to <FIG> relative to torso <NUM> of person <NUM>, as if person <NUM> was looking forward, forcing remote center joint <NUM> into an extended position. Here, imaginary axis <NUM> between first point <NUM> and second point <NUM> remains passing through persons neck.

Base segment <NUM> may be coupled to torso frame <NUM> which is coupled to torso <NUM> of person <NUM>. On of skill in the art may understand that for the neck supporting exoskeleton <NUM>, upper spine <NUM> may be coupled to torso <NUM> of person <NUM> in a manner equivalent to that discussed above for shoulder supporting exoskeleton <NUM>. Terminal segment <NUM> may be coupled to head pillow <NUM> configured to contact the head <NUM> of person <NUM> and apply a supportive force.

In some embodiments as shown in <FIG>, remote center joint <NUM> may further comprise spring <NUM> coupled between at least two segments. Spring <NUM> may be configured to bias remote center joint <NUM> into an extended position. When the head <NUM> of person <NUM> rotates backwards relative to torso <NUM> of person <NUM>, spring <NUM> causes remote center joint <NUM> to resist the motion of head pillow <NUM> relative to torso frame <NUM> to at least partially support the weight of the head <NUM> of person <NUM>. When the head <NUM> of person <NUM> rotates forwards relative to torso <NUM> of person <NUM>, spring <NUM> causes remote center joint <NUM> to assist the motion of head pillow <NUM> relative to torso frame <NUM> to at least partially support the weight of the head <NUM> of person <NUM>. One of skill in the art may appreciate that as a part of a neck supporting exoskeleton <NUM>, remote center joint <NUM> may be configured to support sideways or forward rotation of the head <NUM> of person <NUM> relative to torso <NUM> of person <NUM> instead of rearwards motion.

<FIG> and <FIG> shows an embodiment of remote center joint <NUM> configured to accommodate bi-directional spinal twisting motion of torso <NUM> of person <NUM> relative to hips <NUM> of person <NUM>. This may be used as a part of shoulder supporting exoskeleton <NUM>, neck supporting exoskeleton <NUM>, or any other type of wearable device such as a back-supporting exoskeleton, backpack, load carriage device, etc. In this embodiment, remote center joint <NUM> is configured to create imaginary axis <NUM> between first point <NUM> and second point <NUM> passing through persons spine and oriented along the length of persons spine, parallel to gravity line <NUM> when person <NUM> is standing upright. In some embodiments, base segment <NUM> is fixed relative to persons lower torso and terminal segment <NUM> is fixed relative to persons upper torso. When person <NUM> performs a spinal twisting motion, terminal segment <NUM> tracks persons upper torso while base segment <NUM> remains fixed with persons lower torso. Persons upper torso may indicate motion of the rib cage, chest, shoulders, neck, or head. Persons lower torso may indicate motion of the pelvis or lumbar spine. When persons spine is in a neutral position, remote center joint <NUM> may be biased into a flexed position as shown in <FIG>. When persons spine is twisted to the right or the left, remote center joint <NUM> may be biased into an extended position as shown in <FIG>. While accommodating for twisting motion of persons pine, remote center joint <NUM> may transfer forces and toques between terminal segment <NUM> and base segment <NUM>.

As can be seen in <FIG> and <FIG>, each segment of remote center joint <NUM> may consist of one link, with the joints between them arranged in a single supported fashion. This allows each link to overlap with the connected linkages so that remote center joint <NUM> may extend in two directions about imaginary axis <NUM> between first point <NUM> and second point <NUM>. A consequence of this is that when first axis <NUM> aligns with third axis <NUM> and fourth axis <NUM> aligns with sixth axis <NUM> as shown in <FIG>, a singularity occurs where first segment <NUM> can rotate relative to third segment <NUM> without any motion between base segment <NUM> and terminal segment <NUM>. To avoid this singularity as shown in <FIG>, remote center joint <NUM> may further comprise first magnet <NUM> coupled to any of the segments, and second magnet <NUM> coupled to any other segment, wherein first magnet <NUM> and second magnet <NUM> are configured to bias remote center joint <NUM> away from a position in which first axis <NUM> aligns with third axis <NUM> and fourth axis <NUM> aligns with sixth axis <NUM>. First magnet <NUM> and second magnet <NUM> in this orientation will toggle remote center joint <NUM> around this singularity position. In some embodiments, first magnet <NUM> is positioned in line with first axis <NUM> and second magnet <NUM> is positioned in line with third axis <NUM>, wherein first magnet <NUM> is configured to repel second magnet <NUM>. One of skill in the art may understand that first magnet <NUM> and second magnet <NUM> can similarly be placed in line with fourth axis <NUM> and sixth axis <NUM>, respectively.

One of skill in the art may understand that the embodiments of remote center joint <NUM> described herein may be use in many applications. In the field of exoskeletons, remote center joint <NUM> may be used for any other body motion. In addition to those described above, remote center joint <NUM> may be used to allow an exoskeleton to move with a person during motions including but not limited to internal/external shoulder rotation, internal/external hip rotation, wrist pronation/supination, finger flexion, ankle pronation/supination, spinal flexion, or spinal side bending. In addition to the exoskeleton field, one of skill in the art may utilize remote center joint <NUM> for applications in robotics, surgical equipment, tool mounting equipment, or any other device or mechanism where one end must rotate relative to another.

Claim 1:
A remote-center joint (<NUM>) comprising:
a base segment (<NUM>);
a terminal segment (<NUM>);
a first segment (<NUM>) and a third segment (<NUM>) each rotatably coupled to the base segment (<NUM>) about parallel axes (<NUM>, <NUM>), wherein the first segment and the third segment are geared together; and
a second segment (<NUM>) and a fourth segment (<NUM>) each rotatably coupled to the terminal segment about parallel axes (<NUM>, <NUM>), wherein the second segment and the fourth segment are geared together,
wherein the second segment is rotatably coupled to the first segment and the third segment is rotatably coupled to the fourth segment such that the terminal segment is rotatable relative to the base segment about an imaginary axis (<NUM>) that does not pass through any mechanical joint of the remote-center joint.