Movement support apparatus

There is provided a movement support apparatus including a lower limb coupling portion configured to be coupled to a lower limb, an elastic member, a ground contact unit configured to include a ground contact plate coming into contact with a surface and a transmission portion transmitting force generated by the elastic member, and an ankle portion configured to be installed between the lower limb coupling portion and the ground contact unit. The ground contact unit is installed to be displaceable between a position at which the transmission portion comes into contact with the ankle portion and a position at which the transmission portion is uncoupled from the ankle portion.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Japanese Priority Patent Application JP 2013-144490 filed Jul. 10, 2013, the entire contents of which are incorporated herein by reference.

BACKGROUND

The present disclosure relates to a movement support apparatus.

In recent years, biomechanics, in which structures and movement functions of living things are mechanically analyzed, has been actively studied. Further, development of products reducing burdens on human bodies or products to which the structures and movements of living things using such biomechanics are applied has been advanced.

In particular, many studies of erect bipedalism which is a basic human action have been made, and technologies for supporting human walking and running more efficiently based on erect bipedalism mechanisms analyzed using biomechanics have been examined.

For example, JP 2012-501739T discloses an artificial foot and lower limb equipment or the like that supports human walking by applying torque to an ankle joint using an elastic member and a motor.

SUMMARY

Here, in the technology disclosed in JP 2012-501739T, torque is applied to an ankle joint from the elastic member when the angle between a lower limb or a foot part in the ankle joint is within a specific range. Accordingly, in the technology disclosed in JP 2012-501739T, when the angle between the lower limb and the foot part is within the above-mentioned range, torque may be applied in cases other than walking.

Thus, the present disclosure suggests a novel and improved movement support apparatus capable of switching transmission of a force from an elastic member to a joint part irrespective of an angle of a joint portion or a lower limb coupling portion coupled to a lower limb.

According to an embodiment of the present disclosure, there is provided a movement support apparatus including a lower limb coupling portion configured to be coupled to a lower limb, an elastic member, a ground contact unit configured to include a ground contact plate coming into contact with a surface and a transmission portion transmitting force generated by the elastic member, and an ankle portion configured to be installed between the lower limb coupling portion and the ground contact unit. The ground contact unit is installed to be displaceable between a position at which the transmission portion comes into contact with the ankle portion and a position at which the transmission portion is uncoupled from the ankle portion.

As described above, according to an embodiment of the present disclosure, it is possible to switch transmission of a force from the elastic member to the joint portion irrespective of an angle of the joint portion or the lower limb coupling portion coupled to a lower limb.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The description will be made in the following order.

1. Overview of movement support apparatus

1.1 Application example of movement support apparatus

1.2 Operation overview of movement support apparatus

2. Specific configuration of movement support apparatus

2.1 Specific configuration of movement support apparatus

2.2 Functional configuration of movement support apparatus

3. Operation example of movement support apparatus

4. Advantage example of movement support apparatus

<1. Overview of Movement Support Apparatus>

[1.1 Application Example of Movement Support Apparatus]

First, an overview of an embodiment of the present disclosure will be described with reference toFIG. 1.FIG. 1is an explanatory diagram illustrating an application example of a movement support apparatus1according to the embodiment of the present disclosure.

As illustrated inFIG. 1, the movement support apparatus1according to the embodiment of the present disclosure is, for example, an artificial foot put on a user3whose lower limb has been amputated.

The movement support apparatus1supports movement of the user3. Specifically, the movement support apparatus1is mounted on the lower limb of the user3to substitute for the amputated lower limb of the user3and reproduce walking and running functions. The movement support apparatus1according to the embodiment of the present disclosure can be particularly used properly for the user3of which a part including an ankle joint has been amputated since torque can be applied to the ankle joint by an elastic member or the like.

In the present specification, an example in which the movement support apparatus1according to the embodiment of the present disclosure is an artificial foot will be described, but embodiments of the present disclosure are not limited to the example. For example, the movement support apparatus1according to the embodiment of the present disclosure can also be used as movement support equipment put on a user whose walking ability is lowered due to aging, muscle weakness, or the like. For example, the movement support apparatus1according to the embodiment of the present disclosure can also be used as a movement apparatus included in a lower limb of a robot or the like performing bipedal walking.

[1.2 Operation Overview of Movement Support Apparatus]

Next, an overview of an operation of the movement support apparatus1according to the embodiment of the present disclosure will be described with reference toFIGS. 2 to 4.FIG. 2is an explanatory diagram illustrating an operation of a lower limb at the time of walking by a human being.FIG. 3a graph diagram illustrating power (left drawing) output by an ankle joint and an angle (right drawing) of the ankle joint at a movement speed of 1.25 m/s.FIG. 4is an explanatory diagram illustrating an overview of an operation at the time of walking of the movement support apparatus1according to the embodiment of the present disclosure.

First, the walking by a human being can be divided into a step in which a foot part does not come into contact with the ground surface and a step in which the foot part comes into contact with the ground surface. The step in which the foot part comes into contact with the ground surface is further divided into six steps “A” to “F,” as illustrated inFIG. 2.

Specifically, the step in which the foot part comes into contact with the ground surface can be divided in to step “A” in which the heel comes into contact with the ground surface, step “B” in which the entire bottom surface of the foot part including the tip of the toe comes into contact with the ground surface, step “C” in which the same positional relation as that when the lower limb and the foot part are upright to the ankle joint is realized, step “D” in which the heel is uncoupled from the ground surface, step “E” in which the foot part is kicking the ground surface, and step “F” immediately before the tip of the toe is uncoupled from the ground surface. When the foot part uncoupled from the ground surface comes into contact with the ground surface from the heel again, the step returns to step “A.”

Here, the power (left drawing) output by the ankle joint at the time of walking and the angle (right drawing) of the ankle joint at the time of walking will be described in correspondence with the above-described steps of the walking with reference toFIG. 3. InFIG. 3, corresponding positions of steps “A” to “F” ofFIG. 2in the graph ofFIG. 3are denoted with signs.

The left drawing ofFIG. 3shows the power output by the ankle joint at the time of walking and specifies that a direction (hereinafter referred to as a plantar flexion direction) in which the lower limb is bent toward an opposite side to the tip of the toe is positive and a direction (hereinafter referred to as a dorsiflexion direction) in which the lower limb is bent toward the toe tip side with respect to the foot part is negative. The right drawing ofFIG. 3shows a change in the angle of the ankle joint at the time of walking and specifies that a positional relation between the lower limb and the foot part at the time of erecting is 0°, a direction (hereinafter referred to as a dorsiflexion direction) in which the lower limb is bent toward the toe tip side with respect to the foot part is positive, and a direction (hereinafter referred to as a plantar flexion direction) in which the lower limb is bent toward the opposite side to the tip of the toe is negative.

As illustrated in the left drawing ofFIG. 3, the maximum absolute value of the power output by the ankle joint at the time of walking from step “A” to step “C” is 50 W. On the other hand, it is necessary for the ankle joint to output the absolute value of power of 250 W or more through step “D” and step “E” in which an operation in which the foot part kicks the ground surface is performed.

Accordingly, for example, when the power output by the ankle joint described above is substituted using a motor, it is necessary to use the motor capable of outputting the power necessary at step “D” and step “E.” However, since a motor having large output power has a large size, the motor is heavy. For this reason, mounting a movement support apparatus including a motor having the large output considerably burdens the user3.

As illustrated in the right drawing ofFIG. 3, the angle of the ankle joint at step “A” is 0° and the angle of the ankle joint is negative (on the plantar flexion side) from step “B” to step “C.” Since the ankle joint is rotated with weight shift in the dorsiflexion direction from step “C” to step “D,” the angle of the ankle joint is positive (on the dorsiflexion side). Thereafter, since the ankle joint is rotated with the kicking of the ground surface in the plantar direction from step “D” to step “F,” the angle of the ankle joint is changed from the positive value (dorsiflexion side) to the negative value (plantar flexion side). Thus, in step “D” and step “E” in which it is necessary for the ankle joint to output the maximum power, the angle of the ankle joint becomes negative (the plantar flexion side) for a part of the steps.

Here, in the technology disclosed in JP 2012-501739T, torque is applied to the ankle joint from the elastic member when the angle of the ankle joint is positive (on the dorsiflexion side). Accordingly, in the technology disclosed in JP 2012-501739T, when the maximum power is output by the ankle joint, it is difficult to apply torque from the elastic member to the ankle joint, and thus movement support for the user3may not be performed properly in some cases. Further, in the technology disclosed in JP 2012-501739T, since it is necessary to use a motor capable of outputting the maximum power necessary for the ankle joint in step “D” and step “E,” it is necessary to use a motor with a large size and a heavy weight.

Accordingly, as the result of the thorough repeated examinations on the movement support apparatuses, the inventors of the present disclosure have devised the movement support apparatus1according to the embodiment of the present disclosure to resolve the above-mentioned matters. The movement support apparatus1according to the embodiment of the present disclosure is capable of transmitting force from an elastic member to an ankle joint when the ankle joint outputs the maximum power irrespective of an angle of the ankle joint.

Hereinafter, an overall operation of the movement support apparatus1according to the embodiment of the present disclosure will be described schematically with reference toFIG. 4.FIG. 4is an explanatory diagram schematically illustrating the overall operation of the movement support apparatus1according to the embodiment of the present disclosure. Further, step “A” to step “F” inFIG. 4correspond to step “A” to step “F” described inFIG. 2, respectively.

As illustrated inFIG. 4, for example, the movement support apparatus1according to the embodiment of the present disclosure includes a lower limb coupling portion100, an ankle portion110, a ground contact unit120, an elastic member130, and a motor150. With progress of walking steps, coupling between the elastic member130and the ankle portion110is switched.

InFIG. 4, coupling and non-coupling between the elastic member130and the ankle portion110are expressed by presence and absence of the illustration of the elastic member130. Specifically, in step “A” and step “F” in which the elastic member130is not illustrated, the coupling between the elastic member130and the ankle portion110is not made. Further, in step “B” to step “E” in which the elastic member130is illustrated, the coupling between the elastic member130and the ankle portion110is made, and thus force transmission is possible.

Here, the lower limb coupling portion100is a portion coupled to a lower limb of the user3and the ankle portion110is a portion corresponding to an ankle part of a human being. The ground contact unit120is a portion corresponding to a foot part of a human being. The elastic member130and the motor150apply torque to the ankle portion110.

As illustrated inFIG. 4, the elastic member130is not coupled to the ankle portion110in step “A” in which the heel comes into contact the ground surface. Next, in step “B,” the elastic member130is coupled to the ankle portion110when the entire ground contact unit120including the toe tip side comes into contact with the ground surface.

Subsequently, throughout step “B” to step “D,” the elastic member130accumulates elastic energy while the angle of the ankle portion110is rotated in the dorsiflexion direction. Throughout step “D” to step “E,” the elastic member130applies the accumulated elastic energy as torque to the ankle portion110to reduce a load of the motor150. Further, in step “F,” the elastic member130releases the coupling with the ankle portion110when the tip of the toe is uncoupled from the ground surface.

As described above, in the movement support apparatus1according to the embodiment of the present disclosure, the coupling between the elastic member130and the ankle portion110is switched based on ground contact of the entire ground contact unit120. Accordingly, in the movement support apparatus1according to the embodiment of the present disclosure, the torque can be applied from the elastic member130to the ankle portion110in step “D” and step “E” in which the maximum power is necessary in the ankle portion110.

In the above configuration, even when the motor150is used, the maximum output of the motor150can be reduced, thereby reducing the size and the weight of the motor150. Accordingly, the movement support apparatus1according to the embodiment of the present disclosure can reduce a load of the user3. Further, since the movement support apparatus1is reduced in size and weight, the application range of the movement support apparatus1can be increased even for the user3who has had a small part amputated.

<2. Specific Configuration of Movement Support Apparatus>

[2.1 Specific Configuration of Movement Support Apparatus]

Next, a specific configuration of the movement support apparatus1according to the embodiment of the present disclosure will be described with reference toFIG. 5.FIG. 5is an explanatory diagram illustrating the cross-sectional configuration of the movement support apparatus1according to the embodiment of the present disclosure.

As illustrated inFIG. 5, the movement support apparatus1according to the embodiment of the present disclosure includes a lower limb coupling portion101, an ankle portion111, a ground contact unit121, an elastic member131, a coupling plate141, and a heel-side ground contact plate143. The ground contact unit121includes a ground contact plate122, a slider plate123, a transmission portion126including an ankle-side transmission portion124and an elastic-member-side transmission portion125, an abutting portion127, and a ground-contact unit coupling plate129.

One side of the lower limb coupling portion101is coupled to a lower limb of the user3and the other side thereof is coupled to the ankle portion111. Accordingly, the lower limb coupling portion101can couple the lower limb of the user3coupled via another artificial foot part, an adapter, or the like to the ankle portion111and the ground contact unit121.

The ankle portion111is installed between the lower limb coupling portion101and the ground contact unit121. The ankle portion111has a circular shape on the plane perpendicular to the ground surface and including a movement direction of the user3and a rotational mechanism that is rotatable around an axis perpendicular to the plane. The ankle portion111can rotate the coupled lower limb coupling portion101by the rotational mechanism.

The ankle portion111includes a motor (not illustrated) applying torque to the rotational mechanism to which the above-described lower limb coupling portion101is coupled. The ankle portion111can apply torque when the lower limb coupling portion101is rotated by the included motor. The ankle portion111may include a Harmonic Drive (registered trademark) which is strain wave gearing to amplify torque to be applied. A method of controlling an output of the motor will be described below.

Here, a part of the outer edge of the ankle portion111is formed in a shape engaging with the ankle-side transmission portion124. Specifically, the part of the outer edge of the ankle portion111is formed with a pinion gear shape engaging with a rack gear included in the ankle-side transmission portion124. Accordingly, when the ankle portion111comes into contact with the transmission portion126, the ankle portion111engages with the rack gear shape of the transmission portion126, so that force can be transmitted from the transmission portion126. The ankle portion111and the ankle-side transmission portion124can convert force of a linear direction from the elastic member131into force of a rotational direction and apply the force to the ankle portion111using the rack-and-pinion mechanism for the force transmission.

The ground contact plate122is formed with a plate shape that extends when the movement direction of the user3is a longitudinal direction and with a shape of which one end on the toe tip side is gently curved in the thickness direction. The ground contact plate122comes into contact with the ground surface on the toe tip side curved in the thickness direction and is coupled to the coupling plate141through the ground-contact unit coupling plate129having a coupling point P on the opposite side to the ground contact side and the position at which the slider plate123is installed. Since the ground contact plate122is a member supporting the weight of the user3and coming into contact with the ground surface, the ground contact plate122is preferably formed of, for example, a material having a high strength that is not easily corroded, such as carbon fiber reinforced plastic.

The slider plate123is a linear slider having a slider groove and is formed on the ground contact plate122. The ankle-side transmission portion124is installed above the slider plate123and the ankle-side transmission portion124slides along the slider groove on the slider plate123.

The slider plate123is formed to be longer than the combined length of the ankle-side transmission portion124and the elastic-member-side transmission portion125, and thus a surplus portion is formed at one end opposite to the elastic-member-side transmission portion125. In such a configuration, the slider plate123can slide the ankle-side transmission portion124to the opposite side to the elastic-member-side transmission portion125when the movement support apparatus1kicks the ground surface, thereby performing kicking the ground surface more smoothly.

The transmission portion126includes the ankle-side transmission portion124formed on the slider plate123and the elastic-member-side transmission portion125coming into contact with the elastic member131. The ankle-side transmission portion124and the elastic-member-side transmission portion125are separated from each other and are coupled by a coupling part with elasticity. In such a configuration, the ankle-side transmission portion124and the elastic-member-side transmission portion125can be isolated from each other when external force is applied, and can return to the contact state when no external force is applied.

The ankle-side transmission portion124is formed in a rack gear shape engaging with the pinion gear formed in the part of the outer edge of the ankle portion111. In such a configuration, when the ankle-side transmission portion124comes into contact with the ankle portion111, the shape of the ankle-side transmission portion124can engage with the shape of the ankle portion111. Thus, the force from the elastic member131can be transmitted to the ankle portion111.

The elastic-member-side transmission portion125is installed between and comes into contact with both of the ankle-side transmission portion124and the elastic member131. In such a configuration, the elastic-member-side transmission portion125can transmit the force from the elastic member131to the ankle-side transmission portion124. The elastic-member-side transmission portion125can be slid on the slider plate123to the side of the elastic member131to elastically deform the elastic member131.

The abutting portion127is installed to be fixed to the coupling plate141on the opposite side to the elastic-member-side transmission portion125with respect to the elastic member131. Accordingly, when the elastic-member-side transmission portion125is slid to the side of the abutting portion127, the abutting portion127can compress the elastic member131between the abutting portion127and the elastic-member-side transmission portion125to elastically deform the elastic member131.

The ground-contact unit coupling plate129is installed to have the coupling point P on both sides of the ground contact plate122. The ground-contact unit coupling plate129couples the ground contact unit121, which includes the ground contact plate122, the slider plate123, the transmission portion126, and the abutting portion127, to the coupling plate141at the coupling point P. In such a configuration, the ground-contact unit coupling plate129can displace the ground contact unit121around the coupling point P between a position at which the transmission portion126comes into contact with the ankle portion111and a position at which the transmission portion126and the ankle portion111are isolated from each other.

Here, the coupling point P is installed such that the ground contact side of the ground contact plate122and the transmission portion126are present on the same side with respect to the coupling point P. In such a configuration, when the ground contact unit121is displaced around the coupling point P, the displacement direction of the ground contact side of the ground contact plate122and the displacement direction of the transmission portion126are identical. Accordingly, when the ground contact plate122comes into contact with the ground surface, the ground contact plate122is displaced upward due to the reactive force from the ground surface and the transmission portion126is also displaced upward. At this time, since the upward displaced transmission portion126comes into contact with the ankle portion111, force can be transmitted from the elastic member131to the ankle portion111. Accordingly, the movement support apparatus1can switch the coupling of the elastic member131and the ankle portion111irrespective of the angle of the lower limb coupling portion101and the ankle portion111.

The elastic member131is installed between the elastic-member-side transmission portion125and the abutting portion127. When the transmission portion126and the ankle portion111come into contact with each other, the elastic member131is compressed to be elastically deformed by the fixed abutting portion127and the elastic-member-side transmission portion125slid with the rotation of the ankle portion111. In such a configuration, the elastic member131applies the repulsive force at the time of the elastic deformation to the ankle portion111through the transmission portion126. Here, for example, the elastic member131may be a coil spring or may be a plate spring, a tension spring, an air spring, or the like.

The coupling plate141is formed in substantially an “L” plate shape and is installed between both sides of the ankle portion111, the ground-contact unit coupling plate129, and the heel-side ground contact plate143. The ankle portion111, the ground-contact unit coupling plate129of the ground contact unit121, and the heel-side ground contact plate143are interposed between the two coupling plates141with the same shape, so that the coupling plates141couples them to each other. InFIG. 5, the coupling plate141present on the closer side is not illustrated to clarify the configuration.

The heel-side ground contact plate143is formed on the heel side which is the rear side in the movement direction of the user3. The heel-side ground contact plate143comes into contact with the ground surface to support the weight of the user3. The heel-side ground contact plate143comes into contact with the ground contact unit121displaced downward due to its weight around the coupling point P to support the ground contact unit121. Here, since the heel-side ground contact plate143is a member supporting the weight of the user3and coming into contact with the ground surface, as in the ground contact plate122, the heel-side ground contact plate143is preferably formed of, for example, a material having a high strength that is not easily corroded, such as carbon fiber reinforced plastic.

In the above-described embodiment, the example in which the elastic member131is installed on the heel side below the ankle portion111has been described. However, embodiments of the present disclosure are not limited to the position of the elastic member131illustrated inFIG. 5. For example, the elastic member131may be a tension spring installed on the heel side with respect to the ankle portion111. Further, the elastic member131may be installed on the heel side so that the extension direction is vertical. Embodiments of the present disclosure are not limited by a type, an installation position, and an installation direction of the elastic member.

In the above-described embodiment, the example in which the elastic member131and the ground contact unit121are separately configured has been described, but embodiments of the present disclosure are not limited to the example. The elastic member131may include the ground contact unit121.

[2.2 Functional Configuration of Movement Support Apparatus]

Next, the functional configuration of the movement support apparatus1according to the embodiment of the present disclosure will be described with reference toFIG. 6.FIG. 6is a block diagram illustrating the functional configuration of the movement support apparatus1according to the embodiment of the present disclosure.

As illustrated inFIG. 6, the movement support apparatus1according to the embodiment of the present disclosure includes an angle sensor161, a torque sensor163, a posture sensor165, a motor control unit153, a motor151, strain wave gearing155, an ankle portion111, and a ground contact unit121. Here, since the ground contact unit121and the ankle portion111are the same as those described with reference toFIG. 5, the detailed description will be omitted herein.

The angle sensor161measures an angle of an ankle joint. Specifically, for example, the angle sensor161measures the angle of the ankle joint by measuring an angle of the ground contact unit121with respect to the lower limb coupling portion101or measuring a rotation angle or the like of the ankle portion111. For example, the angle sensor161may be a sensor including a resolver, a rotary encoder, or a potentiometer.

The torque sensor163measures torque applied to the ankle portion111. Specifically, the torque sensor163measures a sum value of torque applied from the motor151and the elastic member131to the ankle portion111. For example, the torque sensor163may be a sensor including a distortion gauge or a piezoelectric element.

The posture sensor165measures an inclination of the ankle portion111in a space. Specifically, the posture sensor165measures an inclination of the ankle portion111in the vertical direction and the horizontal direction in a space. For example, the posture sensor165may be a sensor including a gyroscope.

The motor control unit153controls an output of the motor151based on information from various sensors. Specifically, the motor control unit153controls an output of the motor151based on information measured by the angle sensor161, the torque sensor163, and the posture sensor165and controls torque applied to the ankle portion111. The motor control unit153may calculate a movement speed based on information measured by the angle sensor161and the torque sensor163and control an output of the motor151based on the movement speed.

The motor control unit153may be configured to include a central processing unit (CPU) which is an arithmetic processing device, a read-only memory (ROM) storing arithmetic parameters, a program, and the like used by the CPU, and a random access memory (RAM) temporarily storing a program used in execution of the CPU, parameters properly changed in the execution, and the like.

The motor151generates torque and applies the torque to the ankle portion111. The strain wave gearing155is, for example, a decelerator called a Harmonic Drive (registered trademark) and amplifies the torque output by the motor151. Specifically, the torque output by the motor151is amplified by the strain wave gearing155and is applied to the ankle portion111.

For example, the rotation of the motor151may be converted in a linear direction by a ball screw or the like, may be converted into an elastic force of a coil spring or the like, and may be applied to the ankle portion111. However, when the strain wave gearing155is used, the size and the weight of a mechanism applying torque from the motor151or the like to the ankle portion111can be reduced. Accordingly, to reduce the burden on the user3, it is more preferable to use the strain wave gearing155. In such a configuration, since the movement support apparatus1can be reduced, an application range of the movement support apparatus1according to the embodiment of the present disclosure can be increased even for the user who has had a small part amputated.

Torque is applied to the ankle portion111by the motor151and the ground contact unit121. Here, the ground contact unit121may include the elastic member131, whether the torque from the elastic member131is applied to the ankle portion111is switched depending on whether the transmission portion126comes into contact with the ankle portion111.

<3. Operation Example of Movement Support Apparatus>

Next, examples of operations of the movement support apparatus1according to the embodiment of the present disclosure will be described with reference toFIGS. 7A to 7F.FIGS. 7A to 7Fare explanatory diagrams illustrating examples of operations of the movement support apparatus1at the walking steps (step “A” to step “F”) according to the embodiment of the present disclosure. Here, since the reference numerals given in the movement support apparatus1and constituent elements inFIGS. 7A to 7Fare the same as the reference numerals given to the constituent elements described with reference toFIG. 5and description thereof is the same, the description will be omitted herein.

As illustrated inFIG. 7A, first, the heel-side ground contact plate143comes into contact with the ground surface in step “A.” At this time, the ankle-side transmission portion124and the ankle portion111do not come into contact with each other so and a gap is empty. Then, the ground contact plate122is displaced downward due to its weight around the coupling point P to come into contact with the heel-side ground contact plate143. In the initial state, the elastic member131has a natural length.

Next, as illustrated inFIG. 7B, the ground contact plate122comes into contact with the ground surface in step “B.” When the ground contact plate122comes into contact with the ground surface, the ground contact plate122is displaced upward around the coupling point P due to the reactive force from the ground surface. Accordingly, the slider plate123and the ankle-side transmission portion124installed on the ground contact plate122are likewise displaced upward, so that the ankle-side transmission portion124comes into contact with the ankle portion111.

Here, since the outer edge of the ankle portion111and the ankle-side transmission portion124are a rack-and-pinion mechanism having the engaging shape, the force can be transmitted as the shapes thereof engage with each other. Further, since the ground contact plate122is displaced upward around the coupling point P, the gap between the ground contact plate122and the heel-side ground contact plate143is empty.

Subsequently, as illustrated inFIG. 7C, the lower limb coupling portion101and the ankle portion111are rotated in the dorsiflexion direction in step “C” more than at the position of step “B.” Since the ankle-side transmission portion124has the shape engaging with the ankle portion111, the ankle-side transmission portion124is slid on the slider plate123with the rotation of the ankle portion111to move the elastic-member-side transmission portion125to the side of the abutting portion127. Accordingly, the elastic member131is compressed between the elastic-member-side transmission portion125and the abutting portion127to apply the repulsive force to the ankle portion111and accumulate elastic energy by the elastic deformation.

Next, as illustrated inFIG. 7D, the heel-side ground contact plate143becomes uncoupled from the ground surface in step “D.” At this time, since the lower limb coupling portion101and the ankle portion111are further rotated in the dorsiflexion direction, the elastic member131is further elastically deformed by the ankle-side transmission portion124and the elastic-member-side transmission portion125to apply the repulsive force to the ankle portion111. In this step, the heel-side ground contact plate143is uncoupled from the ground surface. However, since the side of the tip of the toe of the ground contact plate122comes into contact with the ground surface and receives the reactive force from the ground surface, the contact between the ankle portion111and the ankle-side transmission portion124is not released.

Subsequently, as illustrated inFIG. 7E, kicking the ground surface is performed by the ground contact plate122in step “E.” At this time, the rotation direction of the ankle portion111is changed to the plantar flexion direction after step “D.” Accordingly, the elastic energy accumulated in the elastic member131from step “B” to step “D” is applied as the repulsive force of the elastic member131to the ankle portion111after step “D.” In such a configuration, as described with reference to the right drawing ofFIG. 3, the elastic member131can apply the repulsive force to the ankle portion111through step “D” and step “E” in which power is most necessary in the ankle portion111. When the motor151is used, the maximum value of the motor output can be reduced.

Further, as illustrated inFIG. 7F, the kicking on the ground surface by the ground contact plate122is completed in step “F.” At this time, the ankle portion111is rotated in the plantar flexion direction more than in step “E” and the ankle-side transmission portion124becomes uncoupled from the elastic-member-side transmission portion125with the rotation of the ankle portion111.

Here, when the elastic-member-side transmission portion125and the ankle-side transmission portion124are integrally formed and the length of the elastic member131returns to the natural length inFIG. 7Eand the like, the ankle-side transmission portion124is not able to be further moved to the side of the tip of the toe. In this case, since the ankle portion111engages with the ankle-side transmission portion124, the ankle portion111is not able to be further rotated in the plantar flexion direction, thereby obstructing natural kicking of the user3.

In the movement support apparatus1according to the embodiment of the present disclosure, the ankle-side transmission portion124and the elastic-member-side transmission portion125are configured to be separated from each other. Accordingly, even when the length of the elastic member131returns to the natural length inFIG. 7Eand the like, the ankle-side transmission portion124can be separated from the elastic-member-side transmission portion125to be moved. Accordingly, the ankle-side transmission portion124does not obstruct the rotation of the ankle portion111and the user3can perform natural kicking.

Although not illustrated, when the ground contact plate122becomes away from the ground surface in step “F,” the reactive force received from the ground surface by the ground contact plate122disappears, and thus the ground contact unit121is displaced downward around the coupling point P. Therefore, the contact between the ankle portion111and the ankle-side transmission portion124is released. Here, since the ankle-side transmission portion124and the elastic-member-side transmission portion125are coupled to each other by the coupling part with elasticity, the ankle-side transmission portion124returns to the contact position with the elastic-member-side transmission portion125by the elastic force of the coupling part with the releasing of the contact. In such a configuration, when the movement support apparatus1comes into contact with the ground surface again, the operation returns to step “A” and the same operation can be repeated.

Due to the above-described operations, the movement support apparatus1according to the embodiment of the present disclosure brings the transmission portion126into contact with the ankle portion111to transmit the force from the elastic member131to the ankle portion111when the ground contact plate122comes into contact with the ground surface. When the ground contact plate122moves away from the ground surface, the movement support apparatus1releases the transmission of the force from the elastic member131to the ankle portion111by releasing the contact between the transmission portion126and the ankle portion111. Accordingly, the movement support apparatus1according to the embodiment of the present disclosure can apply the force from the elastic member131to the ankle portion111in step “D” and step “E” in which power is most necessary in the ankle portion111.

<4. Advantage Example of Movement Support Apparatus>

Advantage examples of the movement support apparatus1according to the embodiment of the present disclosure will be described with reference toFIGS. 8A to 8C.FIG. 8Ais a graph diagram illustrating power (left drawing) output by the ankle portion111of the movement support apparatus1at a movement speed of 1.25 m/s and torque (right drawing) applied by the elastic member131and the motor151.FIG. 8Bis a graph diagram illustrating the same parameters as those ofFIG. 8Aat a movement speed of 1.50 m/s andFIG. 8Cis a graph diagram illustrating the same parameters as those ofFIG. 8Aat a movement speed of 1.75 m/s.

Here, in the left diagram of each ofFIGS. 8A to 8C, power output by the motor151is indicated by a solid line and power output by the entire ankle portion111is indicated by a dashed line. In the right drawing of each ofFIGS. 8A to 8C, torque applied by the motor151is indicated by a solid line, torque applied by the elastic member131is indicated by a dotted line, and torque applied to the entire ankle portion111, which is a sum of the torque applied by the motor151and the torque applied by the elastic member131, is indicated by a dashed line. In the left drawing of each ofFIGS. 8A to 8C, the plantar flexion direction is assumed to be positive and the dorsiflexion direction is assumed to be negative, as in the left drawing ofFIG. 3. In the right drawing of each ofFIGS. 8A to 8C, the dorsiflexion direction is assumed to be positive and the plantar flexion direction is assumed to be negative.

As illustrated in the left drawing of each ofFIGS. 8A to 8C, the maximum value of the absolute value of the power output by the entire ankle portion111increases as the movement speed is faster. Specifically, in step “D” and step “E,” the absolute value of the power output by the entire ankle portion111is 250 W at the movement speed of 1.25 m/s, as illustrated inFIG. 8A, is 350 W at the movement speed of 1.50 m/s, as illustrated inFIG. 8B, and is 500 W at the movement speed of 1.75 m/s, as illustrated inFIG. 8C. However, the power output by the motor151is different from the power output by the entire ankle portion111and the absolute value thereof converges at substantially 150 W regardless of the movement speed. This is because in the movement support apparatus1according to the embodiment of the present disclosure, the torque is applied to the ankle portion111by the elastic member131so that the power output to the ankle portion111by the motor151is not increased even in step “D” and step “E.”

Here, in the advantage examples illustrated inFIGS. 8A to 8C, as illustrated in the right drawing of each ofFIGS. 8A to 8C, the elastic force (for example, a spring constant) of the elastic member131is determined so that the torque applied by the elastic member131is greater than the torque applied to the entire ankle portion111. Therefore, a force direction (that is, the sign of the graph) of the torque applied to the ankle portion111by the motor151is an opposite direction to that of the torque applied by the elastic member131. In particular, in step “D” and step “E” in which the movement speed is slow in the left drawings ofFIGS. 8A and 8B, the torque applied to the ankle portion111by the elastic member131is greater than the torque applied by the motor151. Therefore, the sign of the power output by the motor151is opposite to that of the power output by the entire ankle portion111.

The elastic force (for example, a spring constant) of the elastic member131is not limited to the elastic force exemplified above. The elastic force of the elastic member131can be properly selected so that the power necessary in the motor151is minimized in the range of the movement speed used in the movement support apparatus1.

Here, in the movement support apparatus1according to the embodiment of the present disclosure, an elastic deformation amount of the elastic member131is changed by the rotation angle of the ankle portion111from the time point at which the ground contact plate122comes into contact with the ground surface and the ankle portion111and the transmission portion126engage with each other. On the other hand, when the movement speed is faster, the step length of a human being naturally increases. Therefore, the angle of the ankle joint at the time of the contact with the ground surface naturally increases, and thus the rotation angle of the ankle portion111also increases at the time of walking.

Accordingly, in the movement support apparatus1according to the embodiment of the present disclosure, as the movement speed becomes faster and the rotation angle of the ankle portion111increases, the elastic deformation amount of the elastic member131can be increased and the torque applied to the ankle portion111can be increased. As illustrated inFIGS. 8A to 8C, as the movement speed is faster, the power necessary in the ankle portion111increases. Therefore, in the movement support apparatus1according to the embodiment of the present disclosure, the torque applied from the elastic member131to the ankle portion111can be automatically increased according to the movement speed.

When a human being ascends or descends stairs, the feet of the human being come into contact with the stairs from the side of the tips of the toes in an operation of the lower limbs unlike the case described with reference toFIG. 2. In the movement support apparatus1according to the embodiment of the present disclosure, the ankle portion111and the transmission portion126come into contact with each other when the ground contact plate122on the side of the tip of the toe comes into contact with the ground surface. Therefore, even when the foot comes into contact with the ground surface from the tips of the toes, the force can be likewise transmitted to the ankle portion111. Accordingly, the movement support apparatus1according to the embodiment of the present disclosure can be properly used even when a human being ascends or descends stairs.

As described above, in the movement support apparatus1according to the embodiment of the present disclosure, the elastic member131and the ankle portion111come into contact with each other and the force from the elastic member131is transmitted to the ankle portion111when the ground contact unit121comes into contact with the ground surface. Further, when the ground contact plate122is uncoupled from the ground surface, the movement support apparatus1releases the transmission of the force from the elastic member131to the ankle portion111by releasing the contact between the transmission portion126and the ankle portion111. Accordingly, the movement support apparatus1according to the embodiment of the present disclosure can apply the force from the elastic member131to the ankle portion111when the power is most necessary in the ankle portion111.

The movement support apparatus1according to the embodiment of the present disclosure applies the force from the elastic member131to the ankle portion111when the power is most necessary in the ankle portion111, thereby reducing the maximum output of the motor151. Accordingly, in the movement support apparatus1according to the embodiment of the present disclosure, it is possible to reduce the size and the weight of the motor151. Further, it is possible to reduce the load on the user3.

In the movement support apparatus1according to the embodiment of the present disclosure, the entire size of the movement support apparatus1can also be reduced by reducing the size of the motor151. Accordingly, the movement support apparatus1according to the embodiment of the present disclosure can also be applied to the user3who has had a smaller part amputated.

The preferred embodiment of the present disclosure has been described in detail with reference to the appended drawings, but the technical scope of the present disclosure is not limited to the example. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.

In the above-described embodiment, the movement support apparatus1has been described as an artificial leg, but embodiments of the present disclosure are not limited to the example. For example, the movement support apparatus1may be movement support equipment for a user whose walking ability is lowered due to aging, muscle weakness, or the like or may be a movement apparatus included in a lower limb of a robot or the like performing bipedal walking.

Additionally, the present technology may also be configured as below.(1) A movement support apparatus including:

a lower limb coupling portion configured to be coupled to a lower limb;

an elastic member;

a ground contact unit configured to include a ground contact plate coming into contact with a surface and a transmission portion transmitting force generated by the elastic member; and

an ankle portion configured to be installed between the lower limb coupling portion and the ground contact unit,

wherein the ground contact unit is installed to be displaceable between a position at which the transmission portion comes into contact with the ankle portion and a position at which the transmission portion is uncoupled from the ankle portion.(2) The movement support apparatus according to (1),

wherein the ground contact unit performs the displacement around a coupling point, and

wherein the ground contact plate and the transmission portion are installed on a same side with respect to the coupling point.(3) The movement support apparatus according to (1) or (2),

wherein the ground contact plate is a toe tip ground contact plate coming into contact with the surface on a front side in a movement direction, and

wherein the movement support apparatus further includesa heel-side ground contact plate configured to come into contact with the surface on a rear side in the movement direction.(4) The movement support apparatus according to any one of (1) to (3), wherein the transmission portion includes a rack gear and the ankle portion includes a pinion gear engaging with the rack gear.(5) The movement support apparatus according to any one of (1) to (4), wherein the transmission portion includes an ankle-side transmission portion located on a side of the ankle portion and an elastic-member-side transmission portion located on a side of the elastic member and configured to be separated from the ankle-side transmission portion.(6) The movement support apparatus according to (5), wherein the ankle-side transmission portion and the elastic-member-side transmission portion are coupled through a coupling member with elasticity.(7) The movement support apparatus according to any one of (1) to (6), further including:

an actuator configured to apply force to the ankle portion.(8) The movement support apparatus according to (7), wherein the actuator is a motor.(9) The movement support apparatus according to (7), further including:

a conversion portion configured to convert the force of the actuator to be applied to the ankle portion.(10) The movement support apparatus according to (9), wherein the conversion portion is strain wave gearing.(11) The movement support apparatus according to any one of (7) to (10), further including:

at least one of an angle sensor configured to detect an angle of the ankle portion, a torque sensor configured to detect torque applied to the ankle portion, or a posture sensor configured to detect an inclination of the ankle portion,

wherein the actuator controls an output of the actuator based on an output of the sensor.(12) The movement support apparatus according to any one of (1) to (11), wherein the elastic member is one of a coil spring, a plate spring, a tension spring, or an air spring.