JP2010188025A - Mechanical self-weight compensator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a self-weight compensator which aims assisting lower limb rehabilitation and is less risky for a person when used by being mounted on him/her. <P>SOLUTION: The mechanical self-weight compensator includes: a first power transmission mechanism which is pivotally attached onto a joint rotary shaft, so as to transmit a joint rotary angle to a self-weight compensation torque generator incorporated in a link; a second power transmission mechanism which is incorporated in the link, so as to convert the joint rotary angle into the desired extension amount of a spring member incorporated in the link; and the spring member. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a self-weight compensator that can be used by being attached to a patient without using a special power source in lower limb rehabilitation, and a mechanism thereof.

Conventionally, as a device that accurately compensates its own weight using a spring restoring force, a device that can compensate for its own weight torque without depending on posture by using a deformed pulley in Non-Patent Document 1, Patent Document 1, Non-Patent Document 2 discloses a device that can compensate for its own weight torque without depending on the posture without using a complicated structure by stretching a spring so that the natural length is 0 between the vertical axis and the link. Document 3 proposes a self-weight compensator capable of arbitrarily changing the compensation self-weight according to the weight of the wearer of the device by incorporating a device capable of adjusting elasticity. In addition, as a self-weight compensator for rehabilitation, Non-Patent Document 4 is a ceiling-suspended self-weight compensator, and Non-Patent Document 5 and Non-Patent Document 6 are used to compensate for the weight of the upper arm of a wheelchair user As a device, a wheelchair-mounted self-weight compensation device has been proposed. Further, Non-Patent Document 7 proposes a lower limb self-weight compensation device that is mounted with a support on the back. Further, Non-Patent Document 8 proposes a self-weight compensation device using a spring member for the purpose of reducing a load applied to a motor that drives a humanoid joint.

JP2003-181789

N. Ulrich et al .: PASSIVE MECHANICAL GRAVITY COMPENSATION FOR ROBOT MANIPULATORS, Proc. Of the IEEE International Conference on Robotics and Automation, 1536/1541, 1991 J.L. Herder: Development of a Statically Balanced Arm Support: ARMON, Proc. Of the 2005 IEEE 9th International Conference on Rehabilitation Robotics, 1114/1120, 2007 B. M. Wisse et al .: Energy-Free Adjustment of Gravity Equilibrators Using the Virtual Spring Concept, Proc. Of the IEEE 10th International Conference on Rehabilitation Robotics, 742/750, 2007 A. H. A. Stienen et al .: Freebal: dedicated gravity compensation for the upper extremities, Proc. Of the IEEE 10th International Conference on Rehabilitation Robotics, 804/808, 2007 Morita et al .: Journal of Biomechanism Society, Vol. 30, No. 4, 200/204, 2006 B. Mastenbroek et al .: Development of a Mobile Arm Support (Armon): Design Evolution and Preliminary User Experience, Proc. Of the 2007 IEEE 10th International Conference on Rehabilitation Robotics, 1114/1120, 2007 SK Banala, SK Agrawal, A. Fattah, V. Krishnamoorthy, W. Hsu, J. Scholz and K. Rudolph: Gravity Balancing Leg Orthosis and Its Performance Evaluation, IEEE Transaction on Robotics, vol. 22, no. 6, 1228 / 1238, 2006 S. Shirata et al .: Design and Evaluation of a Gravity Compensation Mechanism for a Humanoid Robot, Proc. Of the IEEE / RSJ International Conference on Intelligent Robots and Systems, 3635/3640, 2007

  However, the self-weight compensation device described above has a risk of getting fingers or clothes caught when worn directly on a person, such as when wires or springs are stretched between links, or there is a vertical base. It had a certain structure. In the self-weight compensator that is assumed to be worn on a person as a lower limb rehabilitation device, safety is given the highest priority. In addition, a compact structure is also desired in order to reduce the uncomfortable feeling when worn. For this reason, the conventional self-weight compensator having a structure in which a spring member or a wire is stretched between the links cannot be said to be sufficient from the viewpoint of safety and wearability.

In order to solve such a problem and to construct a self-weight compensation device that can be safely used by being worn by a person, it is necessary to fix a wire or a link stretched between links as in the prior art. There is a need to develop a compact self-weight compensator that does not require a base and can incorporate the entire self-weight compensation mechanism in the link.
The present invention has been made in view of such problems, and aims to assist lower limb rehabilitation, and to provide a self-weight compensation device that is less likely to give a person when worn and used. To do.

In order to achieve the above object, a self-weight compensation device according to claim 1 of the present invention is pivotally mounted on a joint rotation shaft for transmitting a rotation angle of a joint to a self-weight compensation torque generating device built in the link. One power transmission mechanism, a second power transmission mechanism built in the link that converts a joint rotation angle into a desired extension amount of the spring member built in the link, and a spring member.
In this device, by rotating the joint, the rotation of the joint is transmitted to the spring member via the first and second power transmission mechanisms, and the spring member is expanded. At this time, a spring restoring force acts on the second power transmission mechanism as a reaction force obtained by extending the spring member. This reaction force is reversely applied to the joint via the first and second power transmission mechanisms. The reaction torque is generated around the joint.
In the present apparatus, it is considered that the first and second power transmission mechanisms are appropriately configured to compensate the self-weight torque by the reaction force torque generated around the joint by the elasticity of the spring member.
In the self-weight compensator according to claim 1 of the present invention, the first and second power transmission mechanisms are configured so that the extension amount of the spring is proportional to the sine of 1/2 of the joint rotation angle. By configuring the first and second power transmission mechanisms in this way, the reaction torque generated around the joint by the extension of the spring member is given as the sine of the joint rotation angle, and as a result, A torque can be generated around the joint that completely cancels the moment generated by.
Thus, in the self-weight compensator according to claim 1 of the present invention, the self-weight compensation torque is generated using the reaction force generated when the spring member is stretched, so that the spring member is stretched as in the prior art. Self-weight compensation can be performed using only the internal force generated in the link without providing a support column outside.
In addition, since it is not necessary to arrange a mechanism that does not interlock with the movement of the device, such as a column, the entire device can be designed compactly, so that not only safety is improved, but also operability is improved and the device is reduced in weight. Can do.
The self-weight compensator according to claim 2 of the present invention is a self-weight compensator that can be attached to a lower limb constituted by a link connected by a rotary joint, and a gear that reduces the rotational angular velocity of the joint to 1/2, A first pulley fixed to the gear; a rotatable second pulley having the same radius as the first pulley and pivotally attached to a shaft fixed perpendicular to the link; A wire that crosses and couples the two pulleys, and a spring member having both ends connected to the first and second pulleys via a universal joint, and when the joint is rotated by an angle θ, The first pulley rotates in the opposite direction to the joint by θ / 2, and the second pulley is in the opposite direction to the first pulley by a wire that crosses and connects the first and second pulleys. Rotate by the same angle. As a result, the spring member stretched between the first and second pulleys is parallel to the straight line connecting the shafts of the first and second pulleys.

Will be stretched by a length proportional to. On the other hand, the rotation position of the first and second pulleys also rotates the attachment position of the pulley and the spring member. As a result, each of the first and second pulleys

The reverse elastic force proportional to

It will work with a moment arm proportional to. As a result, the first and second pulleys

A torque proportional to the torque acts in a direction to return the rotation of the pulley. Since the torque acting on the second pulley is transmitted to the first pulley by a wire that crosses and connects the first and second pulleys, the sum of these torques is given to the first pulley.

Torque proportional to is generated. This torque is doubled through the gear and transmitted to the joint. As a result, around the joint

Therefore, accurate weight compensation that does not depend on the posture can be realized by appropriately setting the elastic coefficient of the spring member.
In the self-weight compensator according to claim 2 of the present invention, since the spring member is arranged in parallel with the link, the width required for the gravity compensation mechanism can be remarkably reduced, and a lightweight and compact self-weight compensator can be configured. It has become.

It is a schematic diagram of the 1-link self-weight compensation apparatus of Embodiment 1. It is a schematic diagram of the 2-link self-weight compensator of Embodiment 2.

Embodiments embodying the invention will be described below with reference to the drawings.
(First embodiment)
FIG. 1 is a diagram conceptually showing a self-weight compensation apparatus according to Embodiment 1 of the present invention. The self-weight compensator according to the first embodiment is a self-weight compensator with one degree of freedom that can prevent a fall due to its own weight when tilting forward with the trunk fully extended.
The weight compensation device of the first embodiment has a sole 1 as a base, a gear 2 fixed to the sole 1, a gear 3 having a diameter twice as large as that of the gear 2, and a rotating shaft common to the gear 3. , A pulley 4 fixed to the gear 3, a pulley 6 coupled to the pulley 4 with a wire, and a spring member 5 connected to the pulley 4 and the pulley 6 by a universal joint.
When the spring member 5 is in the upright posture, it is connected so that the natural length becomes 0. When the spring member 5 is tilted to the right side of the angle θ as shown in FIG. 1, the gear 3 rotates clockwise by θ / 2, and the gear 4 Is rotated counterclockwise by the wire by θ / 2. At this time, the spring member 5 is

  Only stretches. Therefore, if the spring constant of the spring member 5 is K, the restoring force is parallel to the link center line at both ends of the spring.

Will work. On the other hand, the spring restoring force and the moment arm between the pulley 4 and the pulley 6 are as shown in FIG.

Therefore, the pulley 4 has a downward moment with respect to the paper surface.

However, the pulley 6 has an upward moment relative to the paper surface.

Will work. Since the pulley 4 and the pulley 6 are connected by a wire, and the pulley 6 is pivotally attached to the link by a free joint, the moment generated in the pulley 4 is −M6 due to the tension acting on the wire. Therefore, the total moment generated by the spring restoring force in the pulley 4 is a downward moment with respect to the page.

It is described by. Since the gear 3 is pivotally connected by a link and a free joint, this should balance the moment applied from the gear 2 to the gear 3. Therefore, the moment applied from the gear 2 to the gear 3 is an upward moment with respect to the page.

The spring constant is expressed as follows: m is the weight of the wearer and the link including the link, l is the distance from the center of gravity to the center of rotation of the gear 2, and g is the acceleration of gravity.

If you choose like

Thus, a torque that completely cancels the moment generated by gravity can be generated.
(Second Embodiment)
FIG. 2 is a diagram conceptually showing a self-weight compensation apparatus according to Embodiment 2 of the present invention. The self-weight compensator according to the second embodiment is a self-weight compensator that is composed of two links and can be completely compensated for torque generated in a joint due to body weight by being attached to a person's lower limb.
The self-weight compensation device according to the second embodiment has a sole 1 as a base, a gear 2 fixed to the sole 1, a gear 3 having a diameter twice as large as the gear 2, and a rotation shaft common to the gear 3. A pulley 4 fixed to the gear 3, a pulley 6 coupled to the pulley 4 with a wire, a spring member 5 connected to the pulley 4 and the pulley 6 with a universal joint, a timing belt 7 connecting the first joint and the second joint, A timing pulley 8 fixed to the bottom 1, a timing pulley 9 rotatably mounted via a rotation shaft and a bearing of the second joint, a gear 10 fixed to the timing pulley, and a diameter twice the diameter of the gear 10 A pulley 11 fixed to the gear 11, a pulley 13 coupled to the pulley 12 with a wire, and a spring member 14 connected to the pulley 12 and the pulley 13 with a universal joint. Composed.
The spring member 5 and the spring member 14 are connected so that the natural length becomes zero when they are in the upright posture.
The self-weight compensator according to the second embodiment maintains the same posture as the gear 8 by the timing belt when the first link is tilted to the angle θ1 and the second link is tilted to the right side of the angle θ2 as shown in FIG. The gear 11 rotates clockwise by (θ1 + θ2) / 2 with respect to the second link. Thus, the spring member 14 is

In the same way as the self-weight compensation device of the first embodiment, the second link is expanded.

It can be seen that this torque is generated.
Similarly, with respect to the torque generated in the first link, the same analysis as that of the self-weight compensation device of the first embodiment can be performed,

It is shown that the torque is generated.
Therefore, the weight of the first link including the wearer and the weight compensator is m1, the distance between the center of gravity and the center of rotation of the gear 2 is l1, and the weight of the second link including the wearer and the weight compensator is m2, the distance from the center of gravity to the center of rotation of the gear 10 is l2, and the spring constant is

Therefore, it is possible to construct a self-weight compensator that completely cancels the gravitational moment.

(Other embodiments)
In the above, the present invention has been described with reference to the first and second embodiments. However, the present invention is not limited to the above-described embodiments, and it is needless to say that the present invention can be appropriately modified and applied without departing from the spirit of the present invention. Absent.

  The self-weight compensation device of the present invention can be used not only for lower limb rehabilitation but also for work assist devices in assembly factories and power assist for heavy machinery. It can also be used as an output assist for the drive system of a humanoid robot.

DESCRIPTION OF SYMBOLS 1 ... Sole 2 used as a base 2 ... Gear 3 ... Gear 4 with a diameter twice as large as the gear 2 ... Pulley 5 fixed to the gear 3 ... Spring member 6 ... Pulley 7 coupled to the pulley 4 with a wire ... Timing belt 8 ... Timing pulley 9 fixed to the sole 1 ... Timing pulley 10 pivotally attached to the second joint ... Gear 11 pivotally attached to the second joint ... Twice the diameter of the gear 10 A gear 12 having a diameter ... a pulley 13 fixed to the gear 11 ... a pulley 14 coupled to the pulley 12 by a wire ... a spring member

Claims (2)

A first power transmission mechanism pivotally mounted on a joint rotation shaft for transmitting a rotation angle of the joint to a self-weight compensation torque generating device built in the link, and a spring member built in the link. The second power transmission mechanism built in the link for converting to a desired amount of deformation and the spring member, and the rotation angle of the joint via the first and second power transmission mechanisms By transmitting to the member, the spring member is extended, and an elastic force is generated in the spring member as an internal force acting in the link, and the reaction force generated at that time is transmitted via the first and second power transmission mechanisms. A self-weight compensator that generates torque around the joint axis by completely transmitting the self-weight of the wearer by transmitting to the joint axis.   A self-weight compensator that can be attached to a lower limb constituted by a link connected by a rotary joint, a gear that reduces the rotational angular velocity of the joint to 1/2, a first pulley fixed to the gear, A rotatable second pulley having the same radius as that of the first pulley and pivotally mounted on a shaft fixed perpendicular to the link; a wire for cross-connecting the first and second pulleys; Is formed by a spring member connected to the first and second pulleys via a universal joint, the rotation angle of the joint is converted to a half rotation angle via the gear, and the first pulley is The second pulley is rotated in the opposite direction to the first pulley by a wire that is rotated by an angle that is ½ of the rotation angle of the joint and that crosses and connects the first and second pulleys. By rotating only the angle, between the first and second pulleys The spring member is stretched in parallel with the straight line connecting the pulley shafts, the spring restoring force and the moment arm between the pulley shafts are made the length given by the cosine of the pulley rotation angle, and the amount of stretch of the spring member Is set to a length given by the sine of the pulley rotation angle, and the torque given by the sine of the rotation angle of each pulley is generated around the axis of the first and second pulleys by the restoring force of the spring member. The generated torque is transmitted to the rotation axis of the joint via the gear and the wire, thereby generating a torque given as a sine function of the rotation angle of the joint around the rotation axis of the joint. A self-weight compensator that completely compensates for its own weight torque