JP2016209983A - Two-joint interlocking shift link mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To instantly switch hardness for holding a load and suppleness for absorbing external force.SOLUTION: A two-joint interlocking shift link mechanism (3) includes: an ankle link mechanism (4) for connecting a foot section (2a) and a lower thigh section (2b); and a knee link mechanism (5) for connecting the lower thigh section (2b) and an upper thigh section (2c). The knee link mechanism (5) is operated so that a speed reduction ratio is increased interlocking with an operation of the ankle link mechanism (4) according to an increase in an ankle angle (θa).SELECTED DRAWING: Figure 5

Description

  The present invention relates to a two-joint gear-shifting link mechanism provided with two interlocking joint mechanisms, and more particularly to a two-joint gear-shifting link mechanism provided on a leg portion or the like of a humanoid walking robot.

  The leg of the humanoid walking robot plays a role of supporting the whole body while being exposed to frequent impacts received from the ground. In the swing phase before the feet float and land, the legs are required to be flexible to absorb external forces in case of a collision with the ground or the outside world. On the other hand, in the stance phase after landing, the hardness that holds its own weight must be quickly recovered in the legs. In order to switch the extremely contradictory properties of suppleness and hardness in a short time, it is necessary to devise the structure of the leg portion.

  Non-Patent Document 1 has proposed a mechanism for reducing the load on the legs supporting the whole body by attaching a high-load spring in parallel to the knee motor of the humanoid walking robot.

  Non-Patent Document 2 has proposed a mechanism in which a planetary gear and a high-load spring are connected in series, and the force transmission characteristics change depending on the behavior of the drive shaft.

  In Non-Patent Document 3, a gap is provided in the connecting portion between the output shaft of the knee motor and the shin link, and the connecting portion between the output shaft and the shin link according to the ground contact state of the leg portion of the humanoid walking robot. We proposed a mechanism to switch the above properties by using the like as a clutch.

S. Shirata et al. Design and evaluation of gravity compensation mechanism for a humanoid robot.In Proc. Of 2007 IEEE / RSJ International Conference on Intelligent Robots and Systems, pp.3635-3640, 2007. Masahiro Takahashi, Tomohiro Koshi, and Koichi Koganezawa. A new mechanism of active / passive composite joint and biped robot using it. The Japan Society of Mechanical Engineers Robotics and Mechatronics'08 Lecture, 1P1-B05, 2008. M. Okada et al. Double spherical joint and backlash clutch for lower limbs of humanoids.In Proc. Of 2003 IEEE International Conference on Robotics and Automation, pp. 491-496, 2003.

  However, the mechanism of Non-Patent Document 1 has a problem that the load on the lower leg is increased during the swing leg period. In the mechanism of Non-Patent Document 2, since the rigidity of the lower leg part of the humanoid walking robot is significantly lowered as a whole, the controllability of the lower leg part is low. In the mechanism of Non-Patent Document 3, the problems of Non-Patent Document 1 and Non-Patent Document 2 are solved, but the control of detecting the ground contact state of the leg by a sensor and transitioning the connection / disconnection of the clutch is complicated, This is disadvantageous for the control of a humanoid walking robot that requires quick response.

  An object of the present invention is to provide a two-joint interlocking transmission link mechanism that does not require complicated feedback of force sensor information and can immediately switch between hardness for holding a load and flexibility for absorbing external force.

  In order to solve the above-described problems, a two-joint interlocking transmission link mechanism according to the present invention connects a first joint link mechanism that connects a first member and a second member, and connects the second member and a third member. The second joint link mechanism, and in conjunction with the operation of the first joint link mechanism according to an increase in the bending angle between the first member and the second member, The second joint link mechanism operates such that the reduction ratio increases.

  In this specification, the “reduction ratio of the link mechanism” means a ratio between the minute displacement angle of the input angle related to the driving node of the four-bar linkage mechanism and the minute displacement angle of the output angle related to the driven node. Shall.

  According to this feature, the reduction ratio of the second joint link mechanism increases in conjunction with the operation of the first joint link mechanism in accordance with an increase in the bending angle between the first member and the second member. When the bending angle between the first member and the second member is small, the flexibility to absorb the external force is required, and when the bending angle between the first member and the second member increases, the hardness that holds the load. If the flexure angle between the first member and the second member is increased in a state where the flexibility to absorb the external force appears by attaching the two-joint interlocking transmission link mechanism to the mechanism that requires the The reduction ratio of the second joint link mechanism increases in conjunction with the operation of the joint link mechanism. For this reason, the flexibility that absorbs the external force is immediately switched to the hardness that holds the load in conjunction with the operation of the first joint link mechanism. As a result, it is possible to provide a two-joint interlocking transmission link mechanism that can immediately switch between the hardness that holds the load and the flexibility that absorbs the external force.

  In the two-joint interlocking transmission link mechanism according to the present invention, the first member corresponds to the ankle of the human body, the second member corresponds to the lower leg of the human body, and the third member corresponds to the upper leg of the human body. It is preferable that the bending angle increases in accordance with a transition from the swing leg period before the ankle floats in the air to the stance period where the ankle lands and supports its own weight.

  According to the above configuration, the two-joint interlocking transmission link mechanism can be applied to the mechanism related to the leg of the human body.

  In the two-joint interlocking transmission link mechanism according to the present invention, it is preferable that the first joint link mechanism includes a four-joint link mechanism.

  According to the above configuration, it is possible to immediately switch between the hardness that holds the load and the flexibility that absorbs the external force with a simple configuration.

  In the two-joint interlocking transmission link mechanism according to the present invention, the four-joint link mechanism includes a fixed joint fixed to the second member, a driving joint connected to the fixed joint and the first member, and the fixed joint. It is preferable to have a follower connected to a node and an intermediate clause connected to the prime mover and the follower.

  According to the above configuration, the four-bar linkage mechanism can be realized with a simple configuration.

  In the two-joint interlocking transmission link mechanism according to the present invention, the second joint link mechanism is connected to the third member fixing node fixed to the third member, the third member fixing node and the follower node. It is preferable to have a three-member first follower and a third member second follower connected to the third member fixed joint and the intermediate joint.

  According to the said structure, the reduction ratio of a 3rd member 1st follower node and a 3rd member fixed node can be increased.

  In the two-joint interlocking transmission link mechanism according to the present invention, it is preferable that the first joint link mechanism includes a parallel link mechanism.

  According to the said structure, a 1st joint link mechanism can be reached to a 1st member by a parallel link mechanism, and a 1st joint link mechanism can connect a 1st member and a 2nd member.

  In the two-joint-coupled transmission link mechanism according to the present invention, the first member is a foot of a humanoid walking robot, the second member is a lower leg of the humanoid walking robot, and the third member is the The upper leg of the humanoid walking robot is preferable.

  According to the said structure, the property suitable for the leg exercise | movement including the walk of a humanoid walking robot and standing work can be provided to a leg part.

  The two-joint interlocking transmission link mechanism according to the present invention has an effect of being able to immediately switch between the hardness for holding a load and the flexibility for absorbing an external force without using complicated force sensor information feedback.

(A) is a perspective view which shows the mechanism of the leg part of the humanoid walking robot which concerns on Embodiment 1, (b) is the front view. It is a model front view for demonstrating the knee torque which acts as a load to the knee joint in case the said humanoid walking robot stands upright. It is a graph which shows the relationship between the knee torque and the bending angle of a knee joint when the said humanoid walking robot stands upright. It is a schematic diagram for demonstrating the ankle angle in various situations of the said humanoid walking robot, (a) shows the condition where the sole of the said humanoid walking robot is touching the flat ground, (b) Shows a situation where the humanoid walking robot climbs a hill, (c) shows a situation where the humanoid walking robot goes down a hill, and (d) shows a situation where the humanoid walking robot gets over an obstacle. It is a schematic diagram which shows the 2 joint interlocking transmission link mechanism provided in the leg part of the said humanoid walking robot, (a) shows the state which the knee of the said humanoid walking robot extended, (b) shows the said knee. The bent state is shown. It is a schematic diagram which shows the said 2 joint interlocking transmission link mechanism, (a) shows the state which the ankle of the said humanoid walking robot extended, (b) shows the state which the said ankle bent. It is a graph which shows the relationship between the output angle and reduction ratio of the said humanoid walking robot. It is a graph which shows the relationship between the output angle when the ankle angle of the said humanoid walking robot is changed, and a reduction ratio. It is a graph which shows the relationship between the knee angle at the time of a walk, and knee torque. It is a graph which shows the relationship between the knee angle at the time of bending and extending and knee torque. It is a figure which shows operation | movement of the said 2 joint interlocking transmission link mechanism in the state which the ankle of the said humanoid walking robot extended. It is a figure which shows operation | movement of the said 2 joint interlocking transmission link mechanism in the state which the ankle of the said humanoid walking robot extended. It is a figure which shows operation | movement of the said 2 joint interlocking transmission link mechanism in the state which the ankle of the said humanoid walking robot extended. It is a figure which shows operation | movement of the said 2 joint interlocking transmission link mechanism in the state which the ankle of the said humanoid walking robot extended. It is a figure which shows operation | movement of the said 2 joint interlocking transmission link mechanism in the state in which the ankle of the said humanoid walking robot was bent. It is a figure which shows operation | movement of the said 2 joint interlocking transmission link mechanism in the state in which the ankle of the said humanoid walking robot was bent. (A) (b) is a figure which shows the aspect of a reverse drive test. (A) (b) is a figure which shows the aspect of a reverse drive test. It is the graph which compared the theoretical value of the torque and reduction ratio after conversion with respect to a knee angle when an ankle angle is 0 degree | times. It is the graph which compared the theoretical value of the torque and reduction ratio after conversion with respect to a knee angle when an ankle angle is 30 degree | times. It is the graph which compared the theoretical value of the torque and reduction ratio after conversion with respect to a knee angle when an ankle angle is 60 degree | times. It is a schematic diagram which shows the 2 joint interlocking transmission link mechanism provided in the leg part which the knee of the humanoid walking robot which concerns on Embodiment 2 extended. It is a schematic diagram which shows the 2 joint interlocking transmission link mechanism provided in the leg part which the knee of the said humanoid walking robot bent. It is a schematic diagram which shows the two joint interlocking transmission link mechanism provided in the leg part where the knee and the ankle of the said humanoid walking robot were bent.

  Hereinafter, embodiments of the present invention will be described in detail.

(Embodiment 1)
(Basic configuration of the two-joint gear shifting link mechanism 3)
FIG. 1A is a perspective view showing the mechanism of the leg 2 of the humanoid walking robot 1 according to the first embodiment, and FIG. 1B is a front view thereof. The leg 2 of the humanoid walking robot 1 includes a foot 2a (first member) corresponding to the ankle of the human body, a crus 2b (second member) corresponding to the lower leg of the human body, and an upper corresponding to the upper leg of the human body. A thigh 2c (third member).

  The two-joint interlocking transmission link mechanism 3 includes an ankle link mechanism 4 (first joint link mechanism) that connects the foot portion 2a and the crus 2b, and a knee link mechanism that connects the crus 2b and the crus 2c. 5 (second joint link mechanism).

  In conjunction with the operation of the ankle link mechanism 4 corresponding to the increase in the ankle angle θa (the bending angle between the first member and the second member) representing the bending between the foot portion 2a and the crus 2b, The knee link mechanism 5 operates so that the reduction ratio of the link mechanism 5 increases. The ankle angle θa increases in accordance with the transition from the swing leg period before the foot part 2a floats in the air to the landing stage where the foot part 2a lands and supports its own weight.

  The ankle link mechanism 4 includes a link 4a (fixed node) fixed to the crus 2b, a link 4b (drive node) connected to the link 4a and the foot 2a, and a link 4c (linked to the link 4a). This is a four-joint link mechanism having a follower joint) and a link 4d (intermediate joint) connected to the link 4b and the link 4c.

  The knee link mechanism 5 includes a link 5a (third member fixing node) fixed to the upper leg 2c, a link 5b (third member first follower node) connected to the link 5a and the link 4c, a link 5a, A link 5c (third member second driven node) connected to the link 4d.

(Basic concept of the two-joint gear shifting link mechanism 3)
It is not preferable to use an elastic element to constitute a mechanism that immediately switches between the hardness that holds the load and the flexibility that absorbs the external force because the controllability of the mechanism is lowered. The transfer characteristic of the knee motor driving force varies depending on the load. Specifically, it is required to amplify the driving torque of the knee motor in the stance phase where the ankle lands and supports its own weight. It is required to reduce inertia during the swing phase before the ankle floats in the air. Both the amplification factor of the driving torque and the magnitude of the load inertia with respect to the motor are determined by the reduction ratio of the transmitter. Therefore, what should be changed is not the rigidity but the reduction ratio.

  The driving torque amplification requirement in the stance phase is more conspicuous as the knee angle θk representing the knee flexion is larger. On the other hand, the inertia reduction request during the swing phase does not relate to the knee angle θk. It is not preferable to discriminate between the stance period and the free leg period based on the sensor information because the responsiveness of the control is reduced. There is a need to develop a mechanism that can quickly obtain a high reduction ratio without using a sensor.

  In this embodiment, the present inventors pay attention to the fact that the ankle angle θa also increases at the same time when a high reduction ratio is required in the knee in many situations, and the reduction ratio is determined by the interlocking of the ankle joint and the knee joint. A two-joint interlocking transmission link mechanism 3 in which the angle changes is proposed.

  First, the effectiveness of such a two-joint interlocking transmission link mechanism 3 will be examined through a thought experiment. The knee joint is based on a four-joint link mechanism (knee link mechanism 5). The four-joint link mechanism provided in the knee joint has a mechanism in which the reduction ratio increases according to the bending angle even if it is a single unit. Furthermore, one section of the four-link mechanism is replaced with a displacement enlarging mechanism (ankle link mechanism 4) composed of the lower leg and the ankle, and the reduction ratio change rate of the knee link mechanism 5 increases as the ankle angle θa increases. I am doing so. A two-joint interlocking transmission link mechanism 3 according to the present embodiment was prototyped, and it was confirmed that a desired reduction ratio characteristic was obtained with respect to bending of the knee angle θk and the ankle angle θa.

(Knee joint load torque of humanoid walking robot 1)
FIG. 2 is a schematic front view for explaining the knee torque τ acting on the knee joint 8 when the humanoid walking robot 1 is upright based on the load Mg. The same components as those described with reference to FIG. 1 are denoted by the same reference numerals, and detailed description of these components will not be repeated.

  A knee joint 8 is disposed between the lower leg 2b and upper leg 2c of the leg 2 of the humanoid walking robot 1. As shown in FIG. 1, when the humanoid walking robot 1 is standing still, the knee torque τ acting on the knee joint 8 based on the load Mg is from the viewpoint of the length of the moment arm L. The knee angle θk corresponding to the bending increases as the knee angle increases.

  FIG. 3 is a graph showing the relationship between the knee torque τ and the knee angle θk when the humanoid walking robot 1 is standing upright. The result of the simulation is shown.

  The walking motion includes a walking motion at three different heights of the center of gravity, and the bending / extending motion includes a bending / extending motion at three speeds. Curve C1 corresponds to the flexion and extension movement at speed T = 2. Curve C2 corresponds to the bending / extending motion at speed T = 3, and curve C3 corresponds to the bending / extending motion at speed T = 4. Curves C4, C6, and C8 all correspond to the walking motion in the stance phase. Curve C4 corresponds to the gait walking movement at the first center of gravity height, curve C6 corresponds to the gait walking movement at the second center of gravity height, and curve C8 corresponds to the third center of gravity height. Corresponds to the gait movement during the stance phase. Curves C5, C7, and C9 all correspond to walking movements during the swing phase. Curve C5 corresponds to the walking movement in the swing phase at the first center of gravity height, curve C7 corresponds to the walking motion in the swing leg period at the second center of gravity height, and curve C9 corresponds to the third center of gravity height. Corresponds to the walking movement during the swing phase.

  As shown by the curves C1 to C3, it can be seen that the knee torque τ acting as a load increases as the flexion angle (knee angle θk) of the knee joint 8 increases during flexion and extension. As shown by the curves C4, C6, and C8, it can be seen that the knee torque τ increases as the knee angle θk increases even in the stance phase of the walking motion.

  Therefore, it can be said that the knee torque τ acting as a load on the knee joint 8 in the stance phase is related to the knee angle θk. On the other hand, as indicated by the curves C5, C7, and C9, the knee torque τ acting on the knee joint 8 during the swing phase is substantially constant regardless of the knee angle θk, and no relationship with the knee angle θk is observed. .

  Here, attention is focused on the ankle angle θa of the ankle joint. FIG. 4 is a schematic diagram for explaining the ankle angle θa in various situations of the humanoid walking robot 1. FIG. 4A shows a situation in which the sole of the humanoid walking robot 1 is in contact with the flat ground. (B) shows the situation where the humanoid walking robot 1 climbs the hill, (c) shows the situation where the humanoid walking robot 1 goes down the hill, and (d) shows the situation where the humanoid walking robot 1 shows the obstacle 6. Indicates the situation to get over. The same reference numerals are assigned to the same components as those described above, and detailed description of these components will not be repeated.

  As shown in FIG. 4A, a situation is considered in which the sole of the humanoid walking robot 1 is in contact with the flat ground. In order to maintain a standing position in a situation where the knee is bent greatly during the stance phase, the ankle also needs to be bent. On the other hand, considering the movement of the human body, experience has often shown that the ankle is not bent during the swing phase. From this, it is hypothesized that when the load acting on the knee joint 8 (knee torque τ) is large, the bending angle (ankle angle θa) of the ankle joint is also large. This hypothesis is based on the situation where the sole of the humanoid walking robot 1 is in contact with the flat ground and the ankle is not bent during the swing phase. For this reason, a thought experiment is performed for a situation where the ground is not flat or a situation where the ankle bends during the swing leg period.

  When climbing a hill, when the plantar is in contact with the ground, as shown in FIG. 4 (b), the ankle in the stance phase is more bent than walking on a flat ground. For this reason, when the knee torque τ is large, the tendency of the hypothesis that the ankle angle θa is large becomes more remarkable.

  Conversely, when going down a slope, as shown in FIG. 4C, the ankle angle θa itself is smaller than that on a flat ground. However, the tendency for the ankle flexion angle (ankle angle θa) to increase as the load (knee torque τ) increases becomes the same as when walking on a flat ground. Also, since the ankle does not stretch except in situations where the slope of the slope is extremely large, the above hypothesis can be said to be correct except in extreme situations.

  Further, as a situation where the ankle is bent during the swing leg period, a situation where the humanoid walking robot 1 gets over the obstacle 6 as shown in FIG. In this case, it is desirable that the knee joint 8 behaves firmly so that the leg 2 does not come into contact with the obstacle 6 although the load (knee torque τ) acting on the knee joint 8 is small during the swing phase. The demand for 8 is considered to be close to the demand for a situation where the load acting on the knee joint 8 is large. Therefore, the situation that the ankle is bent during the swing leg period because the humanoid walking robot 1 gets over the obstacle 6 is based on the above hypothesis that the ankle joint bend angle (ankle angle θa) is large when the load is large. There is no denial.

  From the above, there are situations where the above hypothesis is not correct, such as downhills with extremely steep slopes, but the hypothesis is considered to be correct in relatively many situations. From this, a mechanism is constructed in which the reduction ratio of the knee joint 8 increases as the bending angle (ankle angle θa) of the ankle joint increases.

(Specific configuration of the two-joint gear shifting link mechanism 3)
FIG. 5 is a schematic diagram showing the two-joint interlocking transmission link mechanism 3 provided on the leg portion 2 of the humanoid walking robot 1. FIG. 5A shows a state where the knee of the humanoid walking robot 1 is extended. b) shows a state where the knee is bent. 6A and 6B are schematic views showing the two-joint interlocking transmission link mechanism 3. FIG. 6A shows a state where the ankle of the humanoid walking robot 1 is extended, and FIG. 6B shows a state where the ankle is bent.

The performance desired to be realized by the two-joint interlocking transmission link mechanism 3 is as follows.
(i) The reduction ratio changes according to the flexion angle between the knee and the ankle.
(ii) No additional actuator is required for shifting.

  As a mechanism for realizing these performances, a four-bar link mechanism is used. The four-bar linkage mechanism is a reduction mechanism in which a ratio of a minute displacement angle between an input angle and an output angle is a reduction ratio. In addition, the relationship between the input and output of the four-bar linkage is determined by the length of each link. For this reason, the parameters that determine the reduction ratio of the four-bar linkage are the input angle, the output angle, and the length of each link.

  In the present embodiment, a mechanism is proposed in which the input angle of the knee joint is interlocked with the angle of the four-joint link mechanism, and the length of the link changes according to the angle of the ankle joint (ankle angle θa).

  Referring to FIGS. 5 and 6, actuators are connected to the pins b and h. The upper thigh 2c is fixed to the link 5a. The crus 2b is fixed to the link 4a. The foot portion 2a is fixed to the link 4b. There is no link between the pin c and the pin d (virtual link 4v), and the distance Lcd between the pin c and the pin d is the link 4a. It is restrained by 4b, 4c and 4d.

  As shown in FIGS. 5A and 5B, when the ankle posture (ankle angle θa) is constant, even if the knee angle changes, the distance between the pins c, d, e, f, g, and h The positional relationship does not change, and therefore the distance Lcd between the pin c and the pin d does not change. FIGS. 5A and 5B show a state where the knee joint is rotated while keeping the posture of the ankle constant. The links 5a, 5b, and 5c respectively connected to the four pins a, b, c, and d behave as a four-joint link mechanism, thereby realizing a motion of bending the knee.

  The angle of the ankle joint is an ankle angle θa based on the link 4a connected to the pins e · h · c and the link 4b connected to the pins g · h. 6 (a) and 6 (b), when the ankle angle θa is changed, the four-bar linkage mechanism including the links 4a, 4b, 4c, and 4d connected to the pins e, f, g, and h, respectively. The posture changes.

  Here, the pins c, e, and h are connected to the same link 4a, and the pins d, f, and g are connected to the same link 4d. For this reason, when the ankle angle θa increases, the relative position between the pin c and the pin d changes, and the distance Lcd between the pin c and the pin d increases. As a result, the characteristics of the links 5a, 5b, and 5c connected to the pins a, b, c, and d change, and the reduction ratio increases.

  At this time, in the knee link mechanism 5, the angle between the link 5a connected to the pins a and b and the link 5b connected to the pins b and c is restricted by the actuator. For this reason, the angle by pin b * c * d changes with the change of the distance Lcd between the pin c and the pin d. As a result, the position of the lower leg 2b with respect to the upper leg 2c changes. Therefore, the knee angle θk of the knee joint changes at the same time as the ankle angle θa is changed.

From the above, the two-joint interlocking transmission link mechanism 3 according to the embodiment is a mechanism having the following characteristics.
-The reduction ratio produced by the knee link mechanism 5 connected to the pins a, b, c, and d increases as the knee joint flexion angle (knee angle θk) increases.
The length between the pin c and the pin d increases as the bending angle of the ankle joint (ankle angle θa) increases, and accordingly, the knee link mechanism 5 connected to the pins a, b, c, and d. The reduction ratio produced by increases.
-Only the bending angle of the ankle joint (ankle angle θa) cannot be changed independently.

(Motion analysis and reduction ratio change)
Each link length of the two joint interlocking transmission link mechanism 3 is determined so as to satisfy the following conditions.
(i) The knee joint has a movable range of 150 degrees or more.
(ii) The reduction ratio of the knee link mechanism 5 changes monotonously with respect to the change in the length Lcd of the virtual link 4v.

  FIG. 7 is a graph showing the relationship between the output angle of the humanoid walking robot 1 and the reduction ratio. A curve C10 indicates the reduction ratio change when the output angle is changed when the ankle angle θa is constant in the two-joint interlocking transmission link mechanism 3. When the output angle is smaller than 100 degrees, the speed is increased, and when the output angle is 100 degrees or more, the speed is decreased.

  FIG. 8 is a graph showing the relationship between the output angle and the reduction ratio when the ankle angle θa of the humanoid walking robot 1 is changed.

  The change in reduction ratio is shown when the ankle angle θa increases in steps of 10 degrees from the ankle angle θa = 0 degrees to θa = 60 degrees, and the ankle bends. Curve C11 corresponds to the ankle angle θa = 0 degrees. Curve C12 corresponds to ankle angle θa = 10 degrees, and curve C13 corresponds to ankle angle θa = 20 degrees. Curves C14, C15, C16, and C17 correspond to ankle angles θa = 30 degrees, 40 degrees, 50 degrees, and 60 degrees, respectively.

  The reduction ratio increases as the ankle angle θa increases. There is a problem that the magnitude of the reduction ratio according to the ankle angle θa is reversed when the output angle is around 200 degrees. Further, in the curves C15, C16, and C17 corresponding to the ankle angle θa = 40 degrees, 50 degrees, and 60 degrees, there is a problem that a singular point is generated when the output angle is as small as about 50 degrees.

  In order to improve the former problem, the reduction ratio at the middle flexion band used during walking is reduced, and the reduction ratio when the output angle shown in FIG. Judging from the fact that the reduction ratio is sufficient compared to the demand, it was judged acceptable.

  The latter problem takes into account the fact that a singular point is unavoidable in order to increase the reduction ratio in the four-bar linkage mechanism, and that the operation of extending the knee while bending the ankle is low. Thus, the two-joint interlocking transmission link mechanism 3 is employed. In this two-joint interlocking transmission link mechanism 3, the output angle = 42.8 degrees in FIGS. 7 and 8 is set to the knee angle θk = 0 degrees.

  FIG. 9 is a graph showing the relationship between knee angle θk and knee torque τ during walking. FIG. 10 is a graph showing the relationship between knee angle θk and knee torque τ during flexion and extension.

  When the two-joint interlocking transmission link mechanism 3 according to the embodiment is used, when only the knee link mechanism 5 is used, or when the conventional single-joint mechanism is used, the walking motion and the flexion / extension motion shown in FIG. FIGS. 9 and 10 show the required torque (knee torque τ) to the actuator when the mechanism is used.

  A curve C18 shown in FIG. 9 corresponds to a conventional single joint mechanism. A curve C19 corresponds to the knee link mechanism 5. A curve C20 corresponds to the two-joint interlocking transmission link mechanism 3. A curve C21 shown in FIG. 10 corresponds to a conventional single joint mechanism. A curve C22 corresponds to the knee link mechanism 5. A curve C23 corresponds to the two-joint interlocking transmission link mechanism 3.

  Referring to FIG. 9, the curve 20 corresponding to the two-joint interlocking transmission link mechanism 3 has the smallest load on the actuator (knee torque τ). Next, the curve C19 corresponding to the knee link mechanism 5 has the smallest load. The curve C18 corresponding to the conventional single joint mechanism has the largest load.

  Referring to FIG. 10, the curve (23) corresponding to the two-joint interlocking transmission link mechanism 3 has the smallest load on the actuator (knee torque τ). Next, the curve C22 corresponding to the knee link mechanism 5 has the smallest load. The curve C21 corresponding to the conventional single joint mechanism has the largest load.

  As described above, the two-joint interlocking transmission link mechanism 3 has the smallest load, the knee link mechanism 5 has the next smallest load, and the conventional single-joint mechanism has the largest load. As shown in FIG. 10, when the knee angle θk is 90 degrees or more, which is a particularly heavy load, the load of the curve 23 (knee torque τ) corresponding to the two-joint interlocking transmission link mechanism 3 is the conventional single joint. The load of the curve 21 corresponding to the mechanism (knee torque τ) and the load of the curve C22 corresponding to the knee link mechanism 5 (knee torque τ) are reduced, and a desirable result is obtained.

(Operation of 2-joint-coupled transmission link mechanism 3)
FIGS. 11-14 is a figure which shows operation | movement of the 2 joint interlocking transmission link mechanism 3 in the state in which the ankle of the humanoid walking robot 1 was extended. 15 and 16 are diagrams illustrating the operation of the two-joint interlocking transmission link mechanism 3 in a state where the ankle of the humanoid walking robot 1 is bent.

  As a result of the operation of the two-joint interlocking shift link mechanism 3, it was confirmed that the two-joint interlocking shift link mechanism 3 has a movable range of the knee angle θk = 0 ° to 150 ° and the ankle angle θa = 0 ° to 60 °. .

  17 (a), 17 (b), 18 (a), and 18 (b) are diagrams showing aspects of the reverse drive test. With respect to the two-joint interlocking transmission link mechanism 3, the force gauge 9 is connected to the pins a and b from the point P1 shown in FIGS. 17A and 17B at a plurality of knee angles θk and ankle angles θa. A force was applied in a direction perpendicular to the link 5a. However, when the knee angle θk was 120 degrees, the center of rotation of the mechanism was close to the point P1, and the force from the point P1 did not move the two-joint interlocking transmission link mechanism 3. For this reason, force was applied from the point P2 shown in FIGS. 18 (a) and 18 (b).

  Table 1 shows the force applied by the force gauge 9 when the two-joint interlocking transmission link mechanism 3 starts moving when force is applied by the force gauge 9 for each knee angle θk and each ankle angle θa.

  Table 1 shows the results obtained by performing an attempt to apply force 10 times for each posture based on each knee angle θk and each ankle angle θa. Also, the blank in Table 1 indicates that the posture cannot be taken outside the movable range of the two-joint interlocking transmission link mechanism 3.

  FIG. 19 is a graph comparing the converted torque and the theoretical value of the reduction ratio with respect to the knee angle θk when the ankle angle θa is 0 degree. FIG. 20 is a graph comparing theoretical values of torque and reduction ratio after conversion with respect to the knee angle θk when the ankle angle θa is 30 degrees, and FIG. 21 is a conversion with respect to the knee angle θk when the ankle angle θa is 60 degrees. It is the graph which compared the theoretical value of the later torque and reduction ratio.

  The force applied by the force gauge 9 in the experiments of FIGS. 17 and 18 is converted into a torque around the point P shown in FIG. 17A and compared. The converted torque corresponds to the torque around the output shaft of the 4-joint link connected to the knee. For this reason, in the situation where only the speed reducer is connected to the input of the 4-bar link, the converted torque corresponds to the torque obtained by multiplying the resistance torque of the speed reducer by the speed reduction ratio. The result of comparing the converted torque in each posture and the theoretical value of the reduction ratio is shown in FIGS.

  FIG. 19 shows the result when the ankle angle θa = 0 degrees. FIG. 20 shows the result when the ankle angle θa = 30 degrees, and FIG. 21 shows the result when the ankle angle θa = 60 degrees. When the knee angle θk and the ankle angle θa are small, the transition of the measured torque value tends to be close to the theoretical value of the reduction ratio.

  However, as shown in FIG. 21, when the ankle angle θa = 60 degrees and the knee angle θk = 120 degrees, a result contrary to the above tendency was obtained. As a cause, when the knee angle θk and the ankle angle θa are increased and the reduction ratio is increased, the force required for the input shaft to start to move increases, and accordingly the deflection of the link member of the two-joint interlocking transmission link mechanism 3 increases. It is thought that it was because it became. When deflection occurs in the link member, each link length changes, and the obtained reduction ratio changes. In the posture of the two-joint interlocking transmission link mechanism 3 in which the reduction ratio is actually increased, a deflection that can be visually confirmed has occurred. In addition, the prototype 2-joint interlocking transmission link mechanism 3 was so large that the deflection could be visually recognized, but the backlash was relatively small, and the influence of the backlash can be ignored.

(Embodiment 2)
FIG. 22 is a schematic diagram showing a two-joint interlocking transmission link mechanism 3A provided on a leg 2A with a knee extended in a humanoid walking robot 1A according to the second embodiment. FIG. 23 is a schematic diagram showing a two-joint interlocking transmission link mechanism 3A provided on a leg 2A where the knee of the humanoid walking robot 1A is bent. FIG. 24 is a schematic diagram showing a two-joint interlocking transmission link mechanism 3A provided on a leg 2A where the knee and ankle of the humanoid walking robot 1A are bent. The same reference numerals are assigned to the same components as those described above, and detailed description of these components will not be repeated.

  In addition to the knee link mechanism 5 and the ankle link mechanism 4, the two-link interlocking transmission link mechanism 3A is provided with a parallel link mechanism 7 (first joint link mechanism). The leg 2A of the humanoid walking robot 1A has a foot 2a, a crus 2bb, and a crus 2c.

  A link 5a connected to the pins a and b is fixed to the upper thigh 2c. The link 4a connected to the pins e · h and the link 7a connected to the pins h · j are fixed to the crus 2bb. Here, the link 4a and the link 7a are integrally formed. Therefore, the relative positional relationship between the pins e, h, and j does not change. A link 7b connected to the pins i and j is fixed to the foot portion 2a. The link 5a drives the knee joint. The link 7a and the link 7b drive the ankle joint. The rotation of the links 7a and 7b causes the movement of the parallel link mechanism 7 including the link 4b, the link 7b, and the pair of links 7a. The movement of the parallel link mechanism 7 is immediately converted into the movement of a four-joint link mechanism (ankle link mechanism 4) composed of the links 4a, 4b, 4c and 4d, and the length between the pins c and d changes. . The knee motion can be regarded as a motion of a four-joint link mechanism (knee link mechanism 5) composed of links 5a, 5b and 5c and having a variable length between pins c and d.

  Under the condition that the length between the pins c and d is fixed, the ratio of the angle change between the upper thigh 2c and the lower thigh 2bb to the change in the angle formed by the links 5a and 5b decreases. That is, the reduction ratio increases.

  Further, the degree of increase in the reduction ratio becomes more remarkable as the length between the pins c and d is longer. For example, the link 5b shown in FIG. 22 rotates around the pin b in the direction away from the link 5a, so that the link 7b further approaches the link 7a from the bent state as shown in FIG. When the ankle is bent by rotating around the pin j, the posture shown in FIG. 24 is obtained, and the length between the pins c and d increases.

  In the first and second embodiments, the load (knee torque) acting on the knee joint is intended to produce a leg mechanism of a humanoid robot that satisfies the conflicting requirements of high output, high rigidity in the stance phase, and flexibility in the swing phase. A method of pseudo-reading τ) from ankle joint angle information (ankle angle θa) was proposed. In addition, using a four-joint link mechanism, we developed a mechanism in which the reduction ratio increases as the knee joint flexion angle (knee angle θk) and ankle joint flexion angle (ankle angle θa) increase. Went. Except for the case where the knee joint flexion angle (knee angle θk) and ankle joint flexion angle (ankle angle θa) were large, a tendency close to the theory was observed. Therefore, it was found that the two-joint interlocking transmission link mechanism 3 or 3A according to the embodiment exhibits the characteristics as a variable deceleration mechanism. In order to solve a problem in which a tendency different from the theory is found, the two-joint interlocking transmission link mechanism 3 or 3A may be made of a material having a small deflection.

  In the walking motion of the human body, the present inventors have (i) a point in which knees and ankles are bent simultaneously in a scene where the knee is required to be rigid, and (ii) by changing the speed reduction ratio instead of rigidity. Focusing on the fact that an effect equivalent to changing the stiffness is obtained, the reduction ratio of the knee joint is increased as the ankle joint flexion angle (ankle angle θa) increases without directly using the force sensor information. A two-joint interlocking transmission link mechanism 3.3A has been developed.

  The two-joint interlocking transmission link mechanism 3 or 3A according to the first and second embodiments does not use force sensor information, and does not use an active transmission or a passive elastic element such as a high-load spring. High reliability and responsiveness, and therefore high controllability. According to the two-joint interlocking transmission link mechanisms 3 and 3A, the effects of secondary expansion of the maximum knee flexion angle (150 degrees or more) and reduction of foot tip inertia can be obtained.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  An example in which the two-joint interlocking transmission link mechanism 3 or 3A is provided at the foot part 2a, the lower leg part 2b or 2bb, or the upper leg part 2c of the leg part 2 of the humanoid walking robot 1 has been shown. It is not limited. For example, the two-joint interlocking transmission link mechanism 3A may be provided on the electric prosthesis, the leg portion, the lower leg portion, and the upper leg portion of the artificial leg.

  In addition, the two-joint interlocking shift link mechanism 3 or 3A may be provided in the foot mounting part, the lower leg mounting part, or the upper leg mounting part of a power assist suit used for nursing work, transport work, rehabilitation and the like.

  Further, a two-joint interlocking transmission link mechanism 3.3A may be provided on an arm connected to a bucket of a construction machine such as a power shovel.

  INDUSTRIAL APPLICABILITY The present invention can be used for a two-joint interlocking shift link mechanism including two interlocking joint mechanisms, and in particular, can be used for a two-joint interlocking shift link mechanism provided on a leg portion of a humanoid walking robot. it can.

  In addition, the present invention can be used for an electric prosthesis, a foot part of a prosthetic leg, a lower leg part, and an upper leg part. And this invention can also be utilized for the step mounting part, lower leg mounting part, upper leg mounting part of the power assist suit used for care work, conveyance work, rehabilitation, etc.

  For mechanisms that transition discontinuously from one support state to another, such as a leg, the requirement that the stiffness must be changed drastically is common. The present invention can satisfy the above requirements in a simple manner based on the motion of the two joints constituting the leg.

  However, the application field of the present invention is not limited to the field related to the leg. For example, this invention can be utilized also for the arm part of a construction machine. For example, the present invention can be used for an arm connected to a bucket of a power shovel.

1 Humanoid walking robot 2 Leg 2a Foot (first member)
2b Lower leg (second member)
2c Upper leg (third member)
3 2-joint-linked shift link mechanism 4 Ankle link mechanism (first joint link mechanism)
4a Link (fixed clause)
4b link
4c link (following clause)
4d link (intermediate section)
5 Knee link mechanism (second joint link mechanism)
5a Link (third member fixing node)
5b Link (3rd member 1st follower)
5c Link (3rd member 2nd follower)
6 Obstacles 7 Parallel link mechanism (first joint link mechanism)
7a link 7b link aj pin θk knee angle θa ankle angle (flexion angle)

Claims (7)

A first joint link mechanism for connecting the first member and the second member;
A second joint link mechanism for connecting the second member and the third member;
In conjunction with the operation of the first joint link mechanism in response to an increase in the bending angle between the first member and the second member, the second reduction ratio of the second joint link mechanism is increased. A two-joint interlocking transmission link mechanism in which a joint link mechanism operates. The first member corresponds to the ankle of the human body;
The second member corresponds to the lower leg of the human body;
The third member corresponds to the upper leg of the human body;
2. The two-joint interlocking transmission link mechanism according to claim 1, wherein the bending angle increases in accordance with a transition from a swing leg period before the ankle floats and landing to a stance period where the ankle lands and supports its own weight. .   The two-joint interlocking transmission link mechanism according to claim 1, wherein the first joint link mechanism includes a four-joint link mechanism. A fixed joint fixed to the second member;
A driving node coupled to the fixed node and the first member;
A follower connected to the fixed node;
4. The two-joint interlocking transmission link mechanism according to claim 3, further comprising an intermediate node connected to the driving node and the driven node. The second joint link mechanism is a third member fixing node fixed to the third member;
A third member first follower connected to the third member fixed joint and the follower;
The two-joint interlocking transmission link mechanism according to claim 4, further comprising a third member second follower connected to the third member fixed joint and the intermediate joint.   The two-joint interlocking transmission link mechanism according to claim 1, wherein the first joint link mechanism includes a parallel link mechanism. The first member is a foot of a humanoid walking robot;
The second member is a lower leg of the humanoid walking robot;
The two-joint interlocking transmission link mechanism according to claim 1, wherein the third member is an upper leg portion of the humanoid walking robot.

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