초록 ▼

The present invention is related to an articulated joint usable in e.g. robotics and rehabilitation, consisting of a first and second body, rotatably connected to each other, and comprising a third body, equally rotatable around a rotation axis, wherein the third body acts as a lever arm. This lever

The present invention is related to an articulated joint usable in e.g. robotics and rehabilitation, consisting of a first and second body, rotatably connected to each other, and comprising a third body, equally rotatable around a rotation axis, wherein the third body acts as a lever arm. This lever arm is connected via a spring to a pre-tension mechanism, which may be mounted on the second body, while the rotation of the lever arm with respect to the first body is controlled by an actuator. This construction leads to a joint wherein the position can be controlled independently from the compliance of the joint, thereby yielding a mechanism with improved characteristics compared to existing designs.

대표청구항 ▼

1. An articulated joint comprising a first body and a second body joined together so that one body is able to perform a pivoting motion with respect to the other body around a pivoting axis, wherein the joint further comprises: a third body coupled to the first body such that the third body pivots w

1. An articulated joint comprising a first body and a second body joined together so that one body is able to perform a pivoting motion with respect to the other body around a pivoting axis, wherein the joint further comprises: a third body coupled to the first body such that the third body pivots with respect to the first body at the pivoting axis and defining a lever arm having a point on the third body offset from the pivoting axis;an actuator coupled to the first body and to the third body and operable to set an angle between the third body and the first body by pivoting the third body with respect to the pivoting axis of the first body, wherein the actuator can set the angle between the third body and the first body independent of movement of the first body;an elastic element, wherein the elastic element is arranged for exerting a force between the point on the third body and a point on the second body offset from the pivoting axis, wherein the elastic element is capable of being pre-tensioned with a varying pre-tension by a pre-tension mechanism, such that the force exerted by the elastic element on the second body is due to an angle between the second body and the third body on the one hand, and to the pre-tension of the elastic element on the other hand; andthe pre-tension mechanism is operable for changing the pre-tension of the elastic element independent of the angle between the first body and the third body by changing an elongation of the elastic element,wherein, when the actuator is controlled to pivot the third body with respect to the pivoting axis of the first body, the force exerted by the elastic element between the second body and the third body generates a torque on the second body that moves the second body towards the third body with a compliance that is adaptable by the pre-tension mechanism changing the pre-tension of the elastic element. 2. The articulated joint according to claim 1, wherein said pre-tension mechanism and said elastic element are arranged directly between said point on the third body and said point on the second body. 3. The articulated joint according to claim 1, wherein said elastic element is connected to the pre-tension mechanism via a cable, wherein the pre-tension mechanism is mounted on a body selected from the group consisting of: the second body and the third body, and wherein the cable is guided around a guide present on the body on which the pre-tension mechanism is mounted and placed so that the cable passes through the point on the body on which the pre-tension mechanism is mounted, regardless of the relative position of the first body and the second body. 4. The articulated joint according to claim 3, wherein said elastic element is located at a location selected from the group consisting of: between said point on the second body and said point on the third body;between the pre-tension mechanism and said guide;distal of the pre-tension mechanism, as seen from the pivoting axis;between a fixed point on the second body and the guide; andbetween a fixed point on the third body and the guide. 5. The articulated joint according to claim 3, wherein said guide is selected from the group consisting of: a pulley, a protrusion, a hole and a set of pulleys arranged on either side of the cable, thereby forcing the cable to pass through a point. 6. The articulated joint according to claim 1, wherein said elastic element comprises a spring. 7. The articulated joint according to claim 6, wherein the spring is linear. 8. The articulated joint according to claim 1, wherein the actuator operable to set the angle between the third body and the first body is a servo-actuator with position feedback. 9. The articulated joint according to claim 1, wherein the pre-tension mechanism comprises a rotating spool, arranged to be actuated by a second actuator able to cause winding or unwinding of a cable onto or from said rotating spool, and wherein said second actuator is a rotational actuator. 10. The articulated joint according to claim 1, wherein a first distance between the pivoting axis connecting the first body and the second body and said point on the second body and a second distance between the pivoting axis of the third body and said point on the third body are such that a ratio of the first distance to the second distance is greater than 1.5. 11. The articulated joint according to claim 1, wherein said actuator is mounted on a bracket, so that the actuator has a rotation axis coinciding with the pivoting axis of the articulated joint, and wherein said third body is a lever arm placed directly on the actuator. 12. The articulated joint according to claim 1, wherein said actuator arranged for controlling the pivoting of the third body is coupled to the third body through a transmission coupling. 13. The articulated joint according to claim 12, wherein the third body is a gearwheel, which forms a part of a gearing mechanism. 14. The articulated joint according to claim 1, wherein: the second body is able to pivot with respect to the first body around the pivoting axis and a second pivoting axis;said first body and the second body are coupled by a cardan coupling;the third body is mounted for pivoting with respect to a plate on the pivoting axis, perpendicular to said plate; andsaid plate is arranged for pivoting on the second pivoting axis. 15. The articulated joint according to claim 1, wherein: the second body is able to rotate with respect to the first body around the pivoting axis and a second pivoting axis;said first body and the second body are coupled by a cardan coupling equipped with a cross-piece;said third body is mounted pivotally with respect to said cross-piece, whilst being connected through the spring to the pre-tension mechanism on the second body;a fourth body is mounted pivotally with respect to said cross-piece, whilst being connected through a second spring to a second pre-tension mechanism on the first body; andan additional actuator is arranged to actuate pivoting of the fourth body with respect to the cross-piece. 16. The articulated joint according to claim 1, wherein the first body is an elongated arm, and wherein the pivoting axis is essentially parallel to said elongated arm, so that a pivoting motion of the second body around said axis parallel to the elongated arm may be actuated. 17. The articulated joint according to claim 1, wherein: said elastic element is connected to the pre-tension mechanism via a cable;the pre-tension mechanism is mounted on the first body; andthe cable is: guided around a first guide, placed at the pivoting axis in such a way that the cable passes through said pivoting axis, regardless of the relative position of first body and the second body; andguided around a second guide present on a body selected from the group consisting of: the second body and the third body, and placed so that the cable passes through said point on the selected body comprising the second guide regardless of the relative position of the first body and the second body. 18. The articulated joint according to claim 17, wherein said elastic element is located at a location selected from the group consisting of: between said point on the second body and said point on the third body;between the pre-tension mechanism and the first guide;between the pre-tension mechanism and the second guide;between the first and the second guide;distal of the pre-tension mechanism, as seen from the pivoting axis;between a fixed point on the second body and said first guide;between a fixed point on the third body, and said first guide;between a fixed point on the second body and said second guide; andbetween a fixed point on the third body, and said second guide. 19. The articulated joint according to claim 17, wherein said first guide and the second guide are selected from the group consisting of: a pulley, a protrusion, a hole, and a set of pulleys arranged on either side of the cable, thereby forcing the cable to pass through the point on the selected body. 20. The articulated joint according to claim 17, wherein a distance B between the pivoting axis connecting the first body and the second body and said point on the second body and a distance C between a pivoting axis of the third body and said point on the third body are such that a ratio C/B is greater than 1.5. 21. An articulated joint according to claim 1, wherein the pre-tension mechanism comprises a linear actuator. 22. The articulated joint of claim 1, wherein the pre-tension mechanism comprises a second actuator operable to change an elongation of the elastic element. 23. The articulated joint of claim 1, wherein the first, second and third bodies are each formed of a rigid link. 24. The articulated joint of claim 1, wherein the pre-tension mechanism is arranged for changing the pre-tension of the elastic element independent of the relative position between the first body and the second body. 25. An articulated joint comprising a first body and a second body joined together so that one body is able to perform a pivoting motion with respect to the other body around a pivoting axis, wherein the joint further comprises: a third body coupled to the first body such that the third body pivots with respect to the first body at the pivoting axis and defining a lever arm having a point on the third body offset from the pivoting axis;an actuator coupled to the first body and to the third body and operable to set an angle between the third body and the first body by pivoting the third body with respect to the pivoting axis of the first body, wherein the actuator can set the angle between the third body and the first body independent of movement of the first body;an elastic element, wherein the elastic element is arranged for exerting a force between the point on the third body and a point on the second body offset from the pivoting axis; anda pre-tension mechanism operable to biasing the elastic element in a variable amount, wherein the pre-tension mechanism can change a biasing force of the elastic element independent of the angle between the first body and the third body by changing an elongation of the elastic element, such that the force exerted by the elastic element on the second body is due to an angle between the second body and the third body on the one hand, and to the biasing force of the elastic element on the other hand,wherein, when the actuator is controlled to pivot the third body with respect to the pivoting axis of the first body, the force exerted by the elastic element between the second body and the third body generates a torque on the second body that moves the second body towards the third body with a compliance that is adaptable by the pre-tension mechanism changing the biasing force of the elastic element. 26. The articulated joint of claim 25, wherein the first, second and third bodies are each formed of a rigid link. 27. The articulated joint of claim 25, wherein the pre-tension mechanism can change the biasing force of the elastic element independent of the relative position between the first body and the second body.