JP5322147B2 - Foot mechanism of multi-legged walking device - Google Patents

Description

  The present invention relates to a foot mechanism that is attached to and grounded on a leg unit of a multi-legged walking movement device that maintains a standing balance by floor reaction force control.

  A conventional multi-legged walking type mobile device, for example, a biped walking type robot, generally has an upper body unit 110 and leg units 4 and 4 attached to the lower part of the upper body unit 110 as shown in FIG. Yes. The leg unit 4 includes a hip joint part 5, a knee joint part 7 connected to the hip joint part 5 via a thigh link 6, an ankle joint part 9 connected to the knee joint part 7 via a lower leg link 8, and an ankle The foot part mechanism 101 is connected to the joint part 9.

The hip joint portion 5 includes a swing shaft 51 around the Z axis, a swing shaft 52 around the X axis, and a swing shaft 53 around the Y axis. The knee joint portion 7 includes a swing shaft 71 around the Y axis. The ankle joint portion 9 includes a swing shaft 91 around the X axis and a swing shaft 92 around the Y axis. That is, the leg unit 4 has 6 degrees of freedom.
Here, the X-axis direction, the Y-axis direction, and the Z-axis direction refer to the front-rear direction (forward +), the lateral direction (right +), and the vertical direction (upward +) of the biped walking robot 112 ( same as below).

  Each of the swing shafts 51 to 53, 71, 91, 92 is constituted by a drive motor that rotates around the respective shaft. Each drive motor is driven and controlled by a control unit 111 stored in the upper body unit 110.

  The control unit 111 drives a gait generator (not shown) that generates gait data in response to an externally requested operation, and the drive motors of the joints 5, 7, and 9 based on the gait data. A walking control unit (not shown) for controlling.

  The gait generator generates gait data including the target angles, target angular velocities, and the like of the drive motors at the joints 5, 7, and 9. The walking control unit swings the leg unit 4 in a predetermined walking pattern by driving and controlling the drive motors of the joints 5, 7, and 9 according to the gait data. Thereby, the bipedal walking robot 112 realizes bipedal walking.

  Regarding the standing balance maintenance of the biped walking robot as described above, the ZMP norm can be applied. Here, “ZMP (Zero Moment Point)” is the center of pressure of the floor reaction force received by the sole of the robot, and when the sole is a plane, the moment received by the sole from the floor (the horizontal component of ) Is zero. The ZMP norm is a norm that the robot can walk stably without falling if the ZMP is inside a support polygon formed by connecting three or more grounding points with lines.

  Based on this ZMP norm, a multi-leg walking type mobile device is controlled by controlling the state of the robot so that an actual ZMP during walking (hereinafter referred to as an actual ZMP) matches a target ZMP in a predetermined walking pattern. Can maintain the standing balance.

  By the way, a foot mechanism of a conventional multi-legged walking robot often has a sole composed of a single plane. If the sole is a single plane, as shown in FIG. 9 (quoting FIG. 2 of Non-Patent Document 1), the entire sole may not touch the ground, such as riding on the convex portion C when walking on rough terrain. In this case, the area of the support polygon SP is small, and it is difficult to maintain a standing balance.

For this problem, for example, a foot mechanism described in Non-Patent Document 1 has been proposed.
The foot mechanism 201 described in Non-Patent Document 1 has support members 203 that passively move up and down at the four corners of the foot mechanism 201 as shown in FIG. 10 (quoting FIG. 3 of Non-Patent Document 1). It follows the unevenness of the road surface. Each support member 203 is provided with a switch (not shown) that senses grounding. When the switch senses the grounding of all four support members 203, each support member 203 is locked. As a result, the support polygon is quickly formed and held.

Also, a foot mechanism described in Patent Document 1 has been proposed.
As shown in FIG. 11 (cited FIG. 2 of Patent Document 1), the foot mechanism 301 described in Patent Document 1 mainly includes a base portion 302, and a flange portion 331 fixedly disposed near the rear end of the base portion 302. The joint portions (drive motors) 332 and 332 provided at the lower end of the base portion 302 extend substantially side by side from the joint portions 332 and 332 and can swing up and down with respect to the base portion 302. And a pair of foot tip portions 333 and 333 arranged. A triaxial force sensor 334 for obtaining floor reaction force information is provided on the lower surfaces of the distal ends of the heel portion 331 and the toe portions 333 and 333. The joints 332 and 332 are appropriately driven and controlled based on the detection values from the three-axis force sensors 334 so that the heel part 331 and the toe parts 333 and 333 are always grounded at three points even on rough terrain. It has become.
Kenji Hashimoto, Yusuke Sugawara, Akihiro Hayashi, Masami Kawase, Akihiro Ota, Tomoaki Tanaka, Nobutsuka Endo, Nobumasa Sawado, Noritama Hayashi, Ikuo Takanishi: Development of a foot mechanism to improve the illegal ground adaptability of biped robots (3rd report: Realization of rough terrain walking by developing a new holding mechanism), Proc. Of the 24th Annual Conference of the Robotics Society of Japan, 2F15, 2006. JP 2004-90194 A

  However, the foot mechanism described in Non-Patent Document 1 requires a mechanism for moving the support member up and down, a mechanism for locking the support member, a switch for detecting grounding, and the like, and has a complicated configuration.

  Further, the foot mechanism described in Patent Document 1 has a complicated configuration because the foot tip portion swings. The foot mechanism described in Patent Document 1 further requires three three-axis force sensors to obtain floor reaction force information sufficient for standing balance control. In general, since a multi-axis force sensor is expensive and fragile, it is difficult to apply this foot mechanism to a large multi-legged walking type walking device that walks on rough terrain.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to secure the area of the support polygon even when walking on rough terrain and to provide a floor necessary and sufficient for standing balance control. An object of the present invention is to provide a foot mechanism of a multi-legged walking type mobile device having a simple configuration capable of acquiring reaction force information.

In order to solve the above-mentioned problems, the present invention provides (1) a foot mechanism that is attached to the lower end of a leg unit in a multi-legged walking type mobile device in which standing balance is maintained by control using ZMP and is grounded. A base member attached to the lower end of the leg unit; and a support member fixed to the base member and having three grounding points that are not arranged in a straight line, and is configured to be grounded only at the grounding point. A floor reaction force detection device for detecting a floor reaction force at the ground contact point , which is provided in the support member and used for calculating ZMP on a first virtual sole plane including all the ground contact points. Te provides a foot mechanism of the prior SL multi-legged walking type mobile device comprising as only to detect the floor reaction force, in that it comprises an acting in the normal direction of the first virtual sole plane Is.
Here, “foot” refers to a portion corresponding to an ankle to toe in humans, and “leg” refers to a portion corresponding to an ankle to pelvis in humans (hereinafter the same).
The “first virtual sole plane” refers to a plane including (passing through) all the tips (grounding points) of the three support members in the foot mechanism (hereinafter the same). In other words, the “first virtual sole plane” does not coincide with the actual floor surface as shown in FIG. 7 when the tip of the support member rides on the protrusion, for example, on rough terrain. Note that FIG. 7 shows two support members for the foot mechanism for convenience of two-dimensional representation.
In addition, the “floor reaction force acting in the normal direction of the first virtual sole plane including all the grounding points” is, for example, that when the tip of the support member rides on the protrusion on an uneven terrain or the like. When illustrated, it is as shown in FIG.

Further, the present invention provides (2) a foot mechanism that is attached to the lower end of the leg unit in the multi-legged walking type mobile device in which the standing balance is maintained by the control using the ZMP , A base member attached to the lower end, a support member fixed to the base member, including three reference ground points not aligned on a straight line fixed to the base member, and all of the reference ground points Three slide pieces that are slidable on an axis passing through the reference grounding point along the normal direction of the second virtual sole plane, and each have a grounding point in the vicinity of the reference grounding point. The contact point is provided only at the contact point, and the slide member is provided on the support member, and the slide piece is in the direction of the slide and is opposed to the floor reaction force at the contact point. And a floor reaction force detector provided on the support member for detecting the floor reaction force at the ground contact point used for calculating the ZMP on the second virtual sole plane. And a detector for detecting a slide displacement amount of the slide piece, and from the slide displacement amount detected by the detector, only a floor reaction force acting in a normal direction of the second virtual sole plane is obtained. What is calculated is provided. A foot mechanism of a multi-legged walking type moving device is provided.
Here, the “reference grounding point” is a point fixed to the base member defined in the vicinity of the actual grounding point and does not necessarily match the actual grounding point. It refers to the point where there is no problem even if it is handled in the same way as the grounding point.

  The foot part mechanism of the multi-legged walking type moving apparatus of the present invention is configured such that the sole is not flat or curved and is grounded only at the three points of the tip of the support member. Therefore, according to the foot mechanism of the present invention, even on rough terrain, the ground can be reliably grounded at three points, and a support polygon formed by connecting the ground points with lines is ensured.

  Further, according to the foot mechanism of the present invention, the support polygon is ensured even on rough terrain as described above, so it is necessary to provide the foot mechanism with a special mechanism for securing the support polygon. Absent. Therefore, the foot mechanism of the present invention has a simple and robust configuration and is inexpensive.

In addition, according to the foot mechanism of the present invention, a virtual sole plane including each contact point or a reference contact point is defined, and an actual ZMP based on a local coordinate axis fixed to the virtual foot plane is easily calculated. Can do.
In other words, since the ground contact point or the reference ground contact point is fixed with respect to the base member and the coordinates thereof are known, it is a floor reaction force at each contact point and acts in the normal direction of the virtual sole plane. The actual ZMP can be easily calculated simply by detecting the floor reaction force.

  Further, as described above, the actual ZMP can be calculated by detecting only the floor reaction force in the normal direction of the virtual plantar plane. A uniaxial force sensor with a normal direction can be used. Therefore, there is no need to use an expensive and fragile multi-axis force sensor.

Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.
1 is a perspective view showing an example of a foot mechanism according to the present invention, FIG. 2 is a schematic view showing an example of a biped walking robot to which the foot mechanism of FIG. 1 is applied, and FIG. 3 is a foot mechanism of FIG. FIG. 4 is a block diagram showing a configuration of a control unit in the biped walking robot of FIG. 2.

  As shown in FIG. 1, the foot mechanism 1 according to the present embodiment includes a base member 2 attached to a lower end of a leg unit 4 described later, three support members 31, 32, 33 extending from the base member 2, have.

  As shown in FIG. 1, the support members 31, 32, and 33 are connected portions 31a, 32a, and 33a extending from the base member 2, and grounding body portions 31b, 32b, and 33b provided at the tips of the connected portions 31a, 32a, and 33a. And grounding pieces 31d, 32d, and 33d attached to the grounding main body portions 31b, 32b, and 33b via uniaxial force sensors (floor reaction force detection devices) 31c, 32c, and 33c.

  The connecting portions 31a, 32a, 33a are formed in a bar shape, and extend below the base member 2 in different directions.

  The grounding main body portions 31b, 32b, 33b are connected to the tips of the connecting portions 31a, 32a, 33a. Uniaxial force sensors 31c, 32c, 33c and grounding pieces 31d, 32d, 33d are sequentially attached to the lower ends of the grounding main body portions 31b, 32b, 33b.

Ground strip 31d, 32d, 33d has become ground body section 3 1b, 32 b, and 33b side tapered extending downwardly. The grounding pieces 31d, 32d, and 33d are grounded only at the grounding points 31e, 32e, and 33e at the tips thereof.

  The uniaxial force sensors 31c, 32c, and 33c are sheet-like pressure sensors, and detect the floor reaction force received when the foot mechanism 1 is grounded via the grounding pieces 31d, 32d, and 33d. In the uniaxial force sensors 31c, 32c, and 33c, the direction perpendicular to the sheet surface is the detection axis. The uniaxial force sensors 31c, 32c, and 33c have their detection axis directions aligned with the normal direction of the virtual sole plane (first virtual sole plane) P1 that includes all of the ground contact points 31e, 32e, and 33e. Is arranged.

  As shown in FIG. 2, the foot mechanism 1 configured as described above has a base member 2 at the lower end of each leg unit 4 in a biped walking robot 12 having an upper body unit 10 and leg units 4, 4. Can be connected and attached.

  As shown in FIG. 2, the leg unit 4 of the biped robot 12 includes a hip joint portion 5, a knee joint portion 7, an ankle joint portion 9, a thigh link 6 that connects the hip joint portion 5 and the knee joint portion 7, and a knee The lower leg link 8 connects the joint portion 7 and the ankle joint portion 9.

  As shown in FIG. 2, the hip joint portion 5 includes a swing shaft 51 around the Z axis, a swing shaft 52 around the X axis, and a swing shaft 53 around the Y axis. The knee joint portion 7 includes a swing shaft 71 around the Y axis. The ankle joint portion 9 includes a swing shaft 91 around the X axis and a swing shaft 92 around the Y axis. Thereby, the leg unit 4 has 6 degrees of freedom.

  Each of the swing shafts 51 to 53, 71, 91, 92 is constituted by a drive motor that rotates around the respective shaft. Each drive motor includes a rotary encoder that detects the amount of rotation. Each drive motor is driven and controlled by a control unit 11 stored in the upper body unit 10.

  As shown in FIG. 4, the control unit 11 includes a gait generator 11a, a calculator 11b, a corrector 11c, and a drive motor controller 11d.

  The gait generator 11a includes a target angle, a target angular velocity, a target ZMP, and the like of each of the swing shafts 51 to 53, 71, 91, 92 in the leg unit 4 in response to a request operation signal input from the outside. Gait data is generated and output to the correction unit 11c.

  The calculation unit 11 b receives an angle signal of each drive motor from a rotary encoder provided in the drive motor of each joint portion 5, 7, 9 in the leg unit 4. Based on the angle signal, the calculation unit 11b calculates joint state data relating to the angles, angular velocities, and the like of the drive motors of the joints 5, 7, and 9 and outputs the calculated joint state data to the drive motor control unit 11d.

Further, a floor reaction force detection value is input from the uniaxial force sensors 31c, 32c, and 33c in the foot mechanism 1 to the calculation unit 11b. The calculating part 11b calculates actual ZMP based on each floor reaction force detection value in each support member 31,32,33, and outputs it to the correction | amendment part 11c. The actual ZMP is calculated from the following equation.
Here, the following expressions are defined based on the local coordinate axes (see FIG. 3) in which the x-axis and the y-axis are on the virtual sole plane P1. That is, the actual ZMP in the foot mechanism 1 of the present invention is calculated with respect to the local coordinate axis fixed to the virtual sole plane P1.

ｘ_実ｚｍｐ：実ＺＭＰのｘ座標
ｙ_実ｚｍｐ：実ＺＭＰのｙ座標
ｘ_ｉ：床反力を受けている点のｘ座標
ｙ_ｉ：床反力を受けている点のｙ座標
ｆ_ｉ：仮想足底平面Ｐ１に垂直な床反力の大きさ

x _{real zmp} : x coordinate of real ZMP y _{real zmp} : y coordinate of real ZMP x _i : x coordinate of point receiving floor reaction force y _i : y coordinate of point receiving floor reaction force f _i : virtual The magnitude of the floor reaction force perpendicular to the sole plane P1

In the case of the foot mechanism 1 of the present invention, the points receiving the floor reaction force are the ground contact points 31e, 32e, 33e. Therefore, x _i and y _i in the above formulas (1) and (2) include coordinates (x ₁ , y ₁ ) and (x ₂ , y ₂ ) of the grounding points 31e, 32e, and 33e shown in FIG. , (X ₃ , y ₃ ) are substituted.

The uniaxial force sensors 31c, 32c, and 33c are components in the normal direction of the virtual sole plane P1 that includes all of the ground contact points 31e, 32e, and 33e among the floor reaction forces received by the ground contact points 31e, 32e, and 33e. to detect only the detected value is substituted into f _i in the ready above formula (1) and (2).

  The correction unit 11c is configured so that the actual ZMP input from the calculation unit 11b matches the target ZMP input from the gait generation unit 11a or falls within the support polygon SP. Gait data such as target angles 53, 71, 91, and 92, and target speeds are corrected. The corrected gait data is input to the drive motor control unit 11d.

  Based on the difference between the corrected gait data from the correction unit 11c and the joint state data from the calculation unit 11b, the drive motor control unit 11d generates control signals for the drive motors of the joint units 5, 7, and 9. Generate. The drive motor control unit 11d controls the drive of each drive motor by outputting the control signal to each drive motor.

  The biped walking robot 12 configured as described above maintains a standing balance as follows.

  First, the gait generator 11a in the control unit 11 performs gait data such as the target angles, target speeds, and target ZMP of the swing shafts 51 to 53, 71, 91, and 92 based on externally requested operations. Is output to the correction unit 11b.

  Next, the calculation unit 11b calculates joint state data related to the angles, angular velocities, and the like of the drive motors of the joints 5, 7, and 9 based on signals from the rotary encoders provided in the joints 5, 7, and 9. And output to the drive motor controller 11d.

  Next, the uniaxial force sensors 31 c, 32 c, 33 c of the foot mechanism 1 detect the floor reaction force applied to the contact points 31 e, 32 e, 33 e and output the detected value to the calculation unit 11 b of the control unit 11.

  Next, the computing unit 11b calculates the actual ZMP on the virtual sole plane P1 including the ground contact points 31e, 32e, 33e based on the floor reaction force detection values from the uniaxial force sensors 31c, 32c, 33c. , And outputs it to the correction unit 11c.

  Next, the correction unit 11c corrects the gait data from the gait generation unit 11a so that the actual ZMP from the calculation unit 11b matches the target ZMP from the gait generation unit 11a, and the corrected gait. Data is output to the drive motor controller 11d.

  Next, based on the difference between the corrected gait data from the correction unit 11c and the joint state data from the calculation unit 11b, the drive motor control unit 11d determines the drive motors of the joint units 5, 7, and 9. A control signal is generated, and each drive motor is controlled based on the control signal.

  In the biped walking robot 12 configured as described above, the bottom of the foot mechanism 1 is not flat, but the tips of the three support members 31, 32, 33 extending from the base member 2, that is, the grounding points 31e, 32e and 33e are grounded. Therefore, even on rough terrain, the grounding points 31e, 32e, 33e can be reliably grounded, and a support polygon SP formed by connecting the grounding points with lines is secured.

  In addition, according to the foot mechanism 1 of the present invention, the support polygon SP is ensured even on rough terrain as described above, so that a special mechanism for securing the support polygon SP in the foot mechanism 1 is ensured. There is no need to provide. Therefore, the foot mechanism 1 has a simple and robust configuration and is inexpensive.

Further, according to the foot mechanism 1 of the present invention, the virtual sole plane P1 including all the grounding points 31e, 32e, and 33e is defined, and the real ZMP based on the local coordinate axis fixed to the virtual sole plane P1 is easily performed. Can be calculated.
That is, since the point that receives the floor reaction force is fixed to the ground contact points 31e, 32e, and 33e, it is the floor reaction force at each of the ground contact points 31e, 32e, and 33e and the floor reaction in the normal direction of the virtual sole plane P1. The actual ZMP can be easily calculated simply by detecting the force.

  Further, as described above, the actual ZMP can be calculated by detecting only the floor reaction force in the normal direction of the virtual sole plane P1, so that the detection direction is set as the virtual sole plane as the floor reaction force detection device. A uniaxial force sensor with a normal direction of P1 can be used. Therefore, there is no need to use an expensive and fragile multi-axis force sensor.

Further, by performing the standing balance control using the ZMP norm independently for each leg unit 4, it is possible to maintain the standing balance of the entire multi-leg walking type moving apparatus. The foot mechanism 1 can be suitably used. This is because according to the foot mechanism 1 of the present invention, the actual ZMP relating to the local coordinate axes defined on the soles of the foot mechanisms 1 can be easily calculated.
The reason why the standing balance of the entire multi-leg walking type moving apparatus can be maintained by performing the standing balance control using the ZMP norm independently for each leg unit 4 is as discussed below. It is.

一方、各足のＺＭＰについて考えると、足ｉのみのＺＭＰは次のようになる。

多脚歩行式移動装置全体のＺＭＰは、各足のＺＭＰを用いると、次のように表される。

一般にｆ_ｉｊｚ＞０であることから、α_ｉ＞０であり、式（６）から、

である。したがって、単一平面上における多脚歩行式移動装置の接地状態について、次のことがわかる。
・多脚歩行式移動装置全体のＺＭＰは、各足ＺＭＰのつくる凸包内に存在する。
・各足ＺＭＰの作る凸包内における多脚歩行式移動装置全体のＺＭＰの位置は、すべて
の足を考慮した支持多角形内でα_ｉに依存して変化する。
接地しているＮ本の足それぞれの支持多角形の凸包が多脚歩行式移動装置全体の支持多角形であることを考えれば、全体と各足のＺＭＰの関係は次のようになる。
・少なくとも１つの各足ＺＭＰが、その足の支持多角形内（境界を除く）に存在するな
らば、多脚歩行式移動装置全体のＺＭＰは、全体の支持多角形内に存在する。
すなわち、必ずしも多脚歩行式移動装置全体のＺＭＰを考慮しなくても、各足ＺＭＰを各足についてローカルに計測し、各足ＺＭＰを各足の支持多角形内に保つように制御することによって、多脚歩行式移動装置全体の立位バランス保持が可能である。
また、式（６）から、例えば上体を動かして各足に加える重量の割合、つまりα_ｉを変化させることにより、各足ＺＭＰ位置とは独立に、各足ＺＭＰの作る凸包内で多脚歩行式移動装置全体のＺＭＰの位置を操作できる。すなわち、各足ＺＭＰの各足ローカルな制御によって多脚歩行式移動装置全体の立位バランスを保持しつつ、全く独立な制御を上体に適用し、多脚歩行式移動装置全体のＺＭＰを、例えばある単一の足の支持多角形内に移動させることが可能である。これは、多脚歩行式移動装置の歩行運動における立位バランス保持と歩行動作生成を、それぞれ独立した制御で別個に行なうことを可能にする知見である。 [Discussion on a single horizontal plane]
It is assumed that there are i = 1, 2,..., N feet in contact with the grounded state of the multi-legged walking device. The ground point of the foot i is discretized for simplicity, and p _ij (j = 1, 2,..., N _i ).
Here, if the floor is a single plane, the floor reaction force perpendicular to the floor at the ground contact point p _ij is _defined as f _ij , and the ZMP of the entire multi-legged mobile device is derived as follows.

On the other hand, when considering the ZMP of each foot, the ZMP of only the foot i is as follows.

The ZMP of the entire multi-legged walking device is expressed as follows using the ZMP of each leg.

In general, since f _ijz > 0, α _i > 0, and from equation (6),

It is. Therefore, the following can be understood about the ground contact state of the multi-legged walking type mobile device on a single plane.
-The ZMP of the entire multi-legged walking device exists in the convex hull made by each leg ZMP.
• The ZMP position of the entire multi-legged walking movement device within the convex hull created by each foot ZMP varies depending on α _i within the support polygon considering all feet.
Considering that the convex hull of the support polygon of each of the N feet that are in contact with the ground is the support polygon of the entire multi-leg walking type moving apparatus, the relationship between the whole and the ZMP of each foot is as follows.
• If at least one foot ZMP is in the support polygon of that foot (excluding the border), the ZMP of the entire multi-legged walking device is in the overall support polygon.
That is, by measuring each foot ZMP locally for each foot and controlling each foot ZMP within the support polygon of each foot without necessarily considering the ZMP of the entire multi-legged walking device It is possible to maintain the standing balance of the entire multi-legged walking device.
Further, from the equation (6), for example, by changing the proportion of the weight applied to each foot by moving the upper body, that is, α _i , it can The ZMP position of the entire leg-walking mobile device can be operated. That is, while maintaining the standing balance of the entire multi-legged walking device by local control of each foot ZMP, completely independent control is applied to the upper body, and the ZMP of the entire multi-legged walking device is For example, it can be moved into a single foot support polygon. This is a knowledge that enables standing balance maintenance and walking motion generation in the walking motion of the multi-legged walking device to be separately performed by independent control.

[Discussion on rough terrain]
As in the discussion on a single horizontal plane, it is assumed that there are i = 1, 2,... The ground point of the foot i is discretized for simplicity, and p _ij (j = 1, 2,..., N _i ). The foot i is grounded (N _i ≧ 3) at at least three points, and a plane including these three points is defined as a virtual sole plane of the foot i. However, since it is rough ground, the virtual sole plane of each foot is not necessarily on the same horizontal plane.
Even in this case, let the floor reaction force perpendicular to the virtual sole plane i at the ground contact point p _{ij be} f _ij, and for all the vertical floor reaction forces on at least one foot i, f _ij > 0 (j = 1, 2, .., N _i ), the ZMP of the foot i is in the support polygon of the foot i, and the foot i is not peeled off from the ground contact state in the virtual sole plane.
That is, even on rough terrain, each foot ZMP is measured locally for each foot without necessarily defining a new ZMP of the entire multi-legged mobile device and performing complicated analysis, and each foot ZMP is supported. By controlling to keep within the square, it is possible to maintain the standing balance of the entire multi-legged walking movement device.

As mentioned above, although embodiment of this invention was described concretely, this invention is not limited to these.
In principle, the positional relationship between the three contact points in the foot mechanism of the present invention is fixed, but there is no practical problem as long as the displacement is relatively small in the normal direction of the virtual sole plane. Therefore, as shown in FIG. 5, a simple buffering mechanism may be introduced into the support members 31 ′, 32 ′, 33 ′ of the foot mechanism 1 ′.

  That is, the support members 31 ′, 32 ′, 33 ′ are connected to the connecting portions 31 a, 32 a, 33 a extending from the base member 2, and the grounding main body portions 31 b, 32 b, 33 b provided at the tips of the connecting portions 31 a, 32 a, 33 a The slide pieces 31g, 32g, and 33g that are slidably held by the grounding main body portions 31b, 32b, and 33b, and the compression springs that urge the slide pieces 31g, 32g, and 33g in the slide direction and against the floor reaction force (Biasing means) 31f, 32f, and 33f may be included.

  At this time, the slide pieces 31g, 32g, and 33g are composed of shaft portions 31j, 32j, and 33j and grounding portions 31h, 32h, and 33h, as shown in FIG. 5B. The grounding portions 31h, 32h, and 33h are formed in a hemispherical shape that protrudes downward. The grounding portions 31h, 32h, and 33h are made of a flexible material such as hard rubber or urethane. The shaft portions 31j, 32j, 33j are accommodated and guided in the grounding main body portions 31b, 32b, 33b. The slide pieces 31g, 32g, and 33g are arranged so that the slide direction coincides with the normal direction of the virtual sole plane (second virtual sole plane) P2 including all the reference ground points 31m, 32m, and 33m. .

  Here, the reference grounding points 31m, 32m, and 33m are points on the slide axis of the slide pieces 31g, 32g, and 33g, and are fixed points near the actual grounding point, for example, the foot mechanism 1 ′. The bottom points of the slide pieces 31g, 32g, 33g when the foot is not grounded, and the slide pieces 31g, 32g, 33g when the foot mechanism 1 'is grounded on a flat surface so as to receive an even floor reaction force. An appropriate point such as a grounding point is determined in advance.

  The compression springs 31f, 32f, and 33f are disposed between the grounding main body portions 31b, 32b, and 33b and the grounding portions 31h, 32h, and 33h of the slide pieces 31g, 32g, and 33g.

  In the vicinity of the slide pieces 31g, 32g, and 33g, as shown in FIG. 5B, detectors 31k, 32k, and 33k for detecting the slide amount of the slide pieces are arranged. As the detectors 31k, 32k, and 33k, a potentiometer, a laser displacement meter, a gap sensor, or the like can be used.

  The floor reaction force is calculated based on the sliding amounts of the slide pieces 31g, 32g, and 33g detected by the detectors 31g, 32g, and 33g, that is, the contraction amounts of the compression springs 31f, 32f, and 33f, and the Hooke's law.

  According to the foot mechanism 1 ′ provided with the buffer mechanism as described above, the impact when the foot mechanism 1 ′ is grounded is mitigated, and each drive part and each joint part of the multi-leg walking type moving device are protected. be able to.

  Further, the foot mechanism 1 'is a point where the reference grounding points 31m, 32m, and 33m are on the slide shaft, and are fixed points that are close to the actual grounding point (the point that does not displace even if the slide piece is displaced). ). Therefore, as illustrated in FIG. 8, even if the slide pieces 31g, 32g, and 33g slide according to the grounding situation and the reference grounding points 31m, 32m, and 33m do not match the actual grounding point, There is a slight difference in the calculation of the actual ZMP, and there is no problem even if the actual ZMP is calculated by treating the reference grounding point as the grounding point. That is, according to the foot mechanism 1 ′, the actual ZMP based on the local coordinate axis fixed to the virtual sole plane P <b> 2 can be easily calculated as in the above embodiment.

It is a perspective view which shows an example of the foot | leg part mechanism concerning this invention. It is the schematic which shows an example of the bipedal walking robot to which the foot | leg part mechanism of FIG. 1 is applied. It is a figure for demonstrating the method to calculate ZMP in the foot | leg part mechanism of FIG. It is a block diagram which shows the structure of the control unit in the bipedal walking robot of FIG. It is a perspective view which shows the modification of the foot | leg part mechanism concerning this invention. It is the schematic which shows an example of the biped walking type robot concerning a prior art example. It is a figure for demonstrating the 1st virtual sole plane. It is a figure for demonstrating the 2nd virtual sole plane. It is a figure which shows the state at the time of the foot mechanism concerning a prior art example walking on rough terrain. It is a figure for demonstrating the foot part mechanism concerning another prior art example. It is a figure for demonstrating the foot part mechanism concerning another prior art example.

Explanation of symbols

P Virtual foot plane 1 Foot mechanism 2 Base members 31, 32, 33 Support members 31a, 32a, 33a Connection portions 31b, 32b, 33b Grounding body portions 31c, 32c, 33c Single-axis force sensor (floor reaction force detection device)
31d, 32d, 33d Grounding pieces 31e, 32e, 33e Grounding point

Claims (2)

A foot mechanism that is attached to the lower end of a leg unit in a multi-legged walking type mobile device in which a standing balance is maintained by control using ZMP ,
A base member attached to the lower end of the leg unit;
A support member that is fixed to the base member and has three grounding points that are not arranged in a straight line, and is configured to be grounded only at the grounding point;
A floor reaction force detection device for detecting a floor reaction force at the ground contact point , which is provided in the support member and used for calculation of ZMP on a first virtual sole plane including all the ground contact points. and detects only the floor reaction force acting in the direction normal to the front Symbol first virtual sole plane,
A foot part mechanism of a multi-legged walking type moving device. A foot mechanism that is attached to the lower end of a leg unit in a multi-legged walking type mobile device in which a standing balance is maintained by control using ZMP ,
A base member attached to the lower end of the leg unit;
A support member fixed to the base member, and a third virtual ground plane including three reference ground points that are not aligned on a straight line that is fixed to the base member, and a second virtual foot plane that includes all of the reference ground points Slidable on an axis passing through the reference grounding point along the normal direction, and three slide pieces each having a grounding point in the vicinity of the reference grounding point, and grounding only at the grounding point And what is supposed to
An urging means provided on the support member, for urging the slide piece in a direction opposite to the floor reaction force at the ground contact point in the direction of the slide;
A floor reaction force detection device that is provided on the support member and detects a floor reaction force at the ground contact point used for calculation of ZMP on the second virtual sole plane, the slide displacement of the slide piece A detector for detecting the amount, and calculating only the floor reaction force acting in the normal direction of the second virtual sole plane from the amount of slide displacement detected by the detector;
A foot part mechanism of a multi-legged walking type moving device.

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