JPH08369B2 - Walking leg trajectory control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a walking leg motion control device for a walking machine, and more particularly to a walking leg motion trajectory control device suitable for causing the walking machine to walk stably.

[Conventional technology]

In recent years, there is a growing need for mobile robots that perform maintenance and inspection work inside buildings in place of humans. Robots that meet such demands move freely and at high speed in the environment where humans have been working until now,
It needs a function to proceed efficiently, but it also needs a function to move over obstacles in the building and to move through it. In order to meet these demands, various walking machines that move by walking legs have been proposed. As a walking machine of this type, there is one that realizes walking with a large number of walking legs, as shown in, for example, JP-A-59-110575 and JP-A-61-134805.

[Problems to be Solved by the Invention]

In a walking machine equipped with a large number of walking legs, for example, a pair of walking legs are moved alternately for walking. The walking leg for walking includes a section in a standing state in which the foot of the walking leg is landed on the floor and a section in a free leg state in which the walking leg is extended for walking. ,
When switching from the standing state to the swinging state or from the swinging state to the standing state, the speed of the foot of the walking leg in the traveling direction and the speed in the vertical direction change stepwise and are discontinuous. This step-like rapid speed change acts as an impact force on the walking machine, and, for example, the body of the walking machine sways, and there is a problem that it cannot run stably.

The present invention is based on the above-mentioned matters,
An object of the present invention is to provide a walking leg motion locus control device capable of reducing an impact force generated when switching from a standing state to a swinging state or from a swinging state to a standing state.

[Means for solving the problem]

The above object of the present invention is to control a joint portion of a walking leg by a leg drive control unit, and in a walking machine that walks by using the walking leg, when switching between standing and swinging of the walking leg. A foot locus generation section that generates a foot locus in which the foot speed is continuous, and a foot locus from the foot locus generation section is calculated as a target joint angle, and this is calculated. This is achieved by including a target joint angle calculation unit that outputs to the leg drive control unit.

[Action]

The joints of the walking leg are drive-controlled based on the continuous speed of the foot generated by the motion locus generation unit of the foot when the walking leg is switched between standing and swinging. Therefore, the walking leg does not cause a speed difference between its foot and the floor surface, and the impact force at the time of landing and at the time of leaving can be suppressed to a small level. As a result, the walking machine can walk stably.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of a walking machine provided with an embodiment of a walking leg motion trajectory control device of the present invention.
1 is a walking machine, and this walking machine 1 has a body 2 and a body 2
And four walking legs (two walking legs 3 and 4 on one side in the illustrated example) provided on the. These walking legs 3 and 4 are the first joints 3A and 4A provided on the torso 2 and the first joints 3A and 4A.
The first leg 3B, 4B connected to 4A and the first leg 3B, 4B
Second joints 3C and 4C provided at the other end of the second leg, second leg portions 3D and 4D connected to the second joint portions 3C and 4C, and the second leg portion
The third joint portion 3E, 4E connected to the other end of 3D, 4D and this third joint portion
It is composed of foot portions 3F and 4F connected to the joint portions 3E and 4E. A leg drive control unit 5 for driving the walking legs 3 and 4 is connected. The leg drive control section 5 includes actuators 50A to 50D connected to the first joint sections 3A and 4A and the second joint sections 3C and 4C, respectively, and the first joint sections 3A and 4A and the second joint section 3C, The joint angle detection sensors 51A to 51D that detect the joint angle of 4C, and the target joint angle θ from the motion trajectory generation unit 6
The deviations of ₁ , θ ₂ , θ ₃ , θ ₄ and the actual joint angles θ _s1 , θ _s2 , θ _s3 , θ _s4 from the joint angle detection sensors 51A to 51D are calculated, and these deviations are respectively calculated by the actuator 50A. .. to 50D and comparing sections 52A to 52D.

The above-described motion trajectory generation unit 6 is configured such that the body 2 is a motion trajectory generation unit.
60, a motion locus generation unit 70 of the feet 3F, 4F contacting the floor surface,
The data from the walking pattern parameter generation unit 80 that specifies the stride length, the height of foot rise, and the like, the above-described foot locus movement generation unit 70 and torso movement locus generation unit 60, and the length of the walking leg. Walking legs 3,4 based on data from database 90
Target joint angle calculation unit 100 that calculates the target joint angles of the first joint units 3A and 4A and the second joint units 3C and 4C, and a storage unit 110 that stores the target joint angle from the joint angle calculation unit 100. And a walking cycle generator 120 that adjusts the output time interval of the target joint angle.

The above-described foot locus generation unit 70 controls the movement of the walking leg during the switching period between the standing state and the free leg state of the walking leg, and as shown in FIG. The standing leg foot position generating section 71 for generating the position and the free leg foot position generating section 700 for generating the position of the foot during the free leg. The foot position generating unit 700 during a swinging leg includes a foot motion during horizontal swinging, a horizontal and vertical acceleration determining unit 701 that determines a foot motion during horizontal swinging, and horizontal and vertical accelerations as a function of time. An acceleration condition setting unit 702 for inputting and setting the values of the horizontal and vertical accelerations of the foot at the time of switching between the standing state and the swinging state to the foot motion / horizontal and vertical direction acceleration determining unit 701 at the time of swinging. And an acceleration integrator 703 that obtains a velocity by integrating each acceleration from the stepping motion and horizontal and vertical acceleration determining unit 701 when swinging the leg, and a foot motion, horizontal and vertical velocity when swinging the leg. The foot motion during swinging, which is determined by a function of time, the horizontal and vertical direction velocity determining unit 704, and the values of the horizontal and vertical speeds of the foot during switching between the standing state and the swinging state are described above. Leg movements when legged, horizontal and vertical velocity determination A speed condition setting unit 705 input and set in the unit 704, a speed integration unit 706 that obtains a position by integrating each speed from the foot motion during horizontal swing and horizontal and vertical direction speed determination unit 704, and a foot during free swing. Foot movement, horizontal and vertical position determiner 707 for determining leg movement, horizontal and vertical position as a function of time
And the horizontal and vertical position of the foot when switching between the standing state and the swinging state, the foot movement during swinging described above,
It is composed of a position condition setting unit 708 that inputs and sets the horizontal and vertical position determining unit 707.

 Next, the operation of the above-described embodiment of the present invention will be described.

FIG. 3 shows the movement form of one walking leg 3,4,
The walking legs 3 and 4 are standing periods W1 in which the feet 3F and 4F are in contact with the ground.
And a period W2 in which the legs 3F and 4F are in a free leg state in which the legs 3F and 4F are separated from the ground F. In this figure, the step length is indicated by a symbol H, and the foot-raising heights of the legs 3F, 4F are indicated by a symbol G, and the step H and the foot-elevating height G can be used as a parameter to freely set the motion during the free leg. .

Next, a method for determining the motion locus of the foot in the free leg state will be described.

FIG. 4 shows changes in the horizontal acceleration of the foot in the swinging state.
It is determined by the horizontal and vertical acceleration determination unit 701. That is, the movements of the legs 3F and 4F are described in the coordinate system of the body fixed in which the horizontal movement of the body 3 in FIG. 3 is stopped, and the horizontal acceleration a _x of the foot in this case is At Is represented by Here, _Am is a coefficient, t is a time, and T is a cycle of one step.

Next, when the walking legs 3 and 4 shift from the standing state to the free leg state, the acceleration condition setting unit 702 sets the foot at t = 0 (when the foot part leaves the floor surface, that is, the free leg) shown in FIG. The horizontal acceleration a _x of the parts 3F and 4F is set to zero so that the acceleration is continuously connected to the acceleration during standing. Also, when shifting from the swinging state to the standing state, The horizontal acceleration a _x of the foot portions 3F and 4F (when the foot portion lands) is set to zero as described above. Then, the change in acceleration is set by connecting a sine curve between them.

Next, the acceleration integrator 203 integrates the equation (1) to obtain the fifth
Obtain the horizontal velocity v _x of the foot shown in the figure. This horizontal speed
v _x is Is represented by Here, C is a coefficient. At this time, the speed condition setting unit 705 starts from −v _B when the horizontal speed v _x is t = 0 so that the boundary condition between the standing leg and the free leg is satisfied. Set to end with. At this time, the speed v _B corresponds to the traveling speed of the body 2. By the speed setting by the speed condition setting unit 705 described above, the toe motion during horizontal swing, horizontal and vertical direction speed determination unit 704 performs the calculation based on the following equation.
That is, at t = 0, from the above equation (2), Therefore, Becomes Therefore, the horizontal velocity v _x is And the above equation (5) is The condition v _x = −v _{B for} is also satisfied. The change in the horizontal speed of the foot during this swing period is shown in the ground coordinate system in the fifth example.
FIG.

Next, the above equation (5) is converted into the horizontal position x in the velocity integration unit 706. This horizontal position x is (6)
It is represented by a formula.

Next, the foot movement at the time of swinging the leg, the horizontal and vertical direction position determining unit 707 determines the condition from the position condition setting unit 708, that is, t =
0 at x = 0, X = 2S, where S is the following calculation based on 1/4 of the step length H and the equation (6). That is, at t = 0, x = 0 = C ... (7) Therefore, C = 0 ... (8) And the speed v _B is Since the (10) equation (9) is substituted into equation and obtains the A _m, Becomes By substituting this A _m into equation (6), the horizontal position x becomes Becomes For reference, by substituting the equation (11) into the equations (5) and (6), the acceleration a _x and the velocity v _x are expressed as the equations (13) and (14), respectively.

Next, the vertical movement of the foot during the swing period will be described.

FIG. 6 shows changes in vertical acceleration of the feet 3F and 4F in the idle leg state. The change characteristic of the acceleration is determined by the foot motion, horizontal and vertical acceleration determination unit 701 when swinging the leg. When the motion of the foot is described in the coordinate system of the body in which the horizontal motion of the body 2 shown in FIG. 3 is stopped, the vertical acceleration a _y of the foot is: Is represented. Where B _m is a coefficient.

Next, the acceleration condition establishing unit 702 instructs the foot motion when swinging the legs and the horizontal and vertical acceleration determining unit 701 when the foot leaves the floor (t = 0) and when landing. The acceleration is set to zero so that the boundary condition of acceleration with Even when the foot lift height G of the foot is maximum, the vertical acceleration is set to zero. Furthermore, this swing period is a characteristic connected by a sine curve. And t =
From 0 Exercise of the foot up to Since the movement up to can be grasped as the movement in which the initial position and the traveling direction are opposite, here from t = 0 Up to.

The acceleration integrator 703 integrates the equation (15) to obtain the vertical velocity v _y . This vertical velocity v _y is Becomes

Next, the leg movements during horizontal swing and the horizontal and vertical velocity determination units
704 is the speed condition from the speed condition setting unit 705, that is, the foot
When leaving the floor on 3rd and 4th floor (t = 0) and when landing And its midpoint The following calculation is performed under the condition that the velocity is zero so that the boundary condition with the standing motion is satisfied with and. That is, at t = 0 Therefore, the vertical velocity v _y can be calculated by the equations (16) and (17). Becomes This equation (18) is And v _y = 0 is satisfied. FIG. 7 shows the change in vertical velocity at this time.

Next, the velocity integrator 706 obtains the vertical position y by the following equation (19).

Next, the foot movement during horizontal swing, horizontal and vertical position determination unit 707 determines the position condition from position condition setting unit 708, that is, 0 = C at t = 0, And y = G, but the foot-raising height G is from the walking pattern parameter 80. The vertical position is determined according to the following equation.

For reference, the vertical acceleration a _y and the vertical velocity v _y are obtained from the following equations based on the equations (18) and (19), respectively.

Also Similarly, the vertical position y is obtained by the following equation.

FIG. 8 and FIG. 9 show changes in position in the horizontal direction X and the vertical direction Y with respect to time of the legs 3F and 4F during the swing leg period obtained as described above. The position change curves shown in these figures are cycloidal curves when the X axis is the change in time T and the Y axis is the position change in the horizontal and vertical directions.

When the horizontal and vertical movements of the foot during the swing period thus determined are replaced by the trajectory of the ground coordinate system, the result is as shown in FIG. 10, and the position of the torso is fixed. When replaced with the locus of the fixed body coordinate system, the result is as shown in FIG. The locus shown in FIG. 11 is a locus of the feet 3F and 4F obtained by driving the joints of the walking legs 3 and 4.

Next, the foot motion at the time of swinging the leg and the motion of the foot obtained by the horizontal and vertical position determining unit 707 are
Is added to As a result, the target joint angle calculation unit 100 further causes the foot position during standing from the standing foot position generating unit 71 and, for example, the constant velocity linear motion of the trunk from the motion trajectory generation unit 60 of the trunk, and the database 90. Based on the dimensions of the walking legs 3 and 4 and the position of each joint, the target joint angle of each joint is obtained. This target joint angle is stored in the target joint angle storage unit 110, and is output to the leg drive control unit 5 in the walking cycle from the walking cycle generating unit 120. Based on this, the leg drive control unit 5 controls the traveling leg 3,
The respective joints of 4 are driven to cause the walking legs 3 and 4 to walk.

As described above, by determining the acceleration and speed of the legs 3F, 4F during the swinging leg so as to satisfy the boundary condition with the standing time, when the legs 3F, 4F land and leave the ground. Since there is no relative motion between the floor surface and the feet 3F, 4F, it is possible to suppress the generation of horizontal and vertical reaction forces due to the collision with the floor surface. Also, since the changes in the acceleration of the feet 3F, 4F can be smoothed, the vibrations of the feet 3F, 4F are suppressed, and the changes in the rotational angular acceleration of each joint are also smoothed, so that the target trajectory can be achieved. Follows well, and the torque change at each joint is smooth. This does not require high performance in terms of torque performance and acceleration performance of the actuator, reduces the weight of the actuator, and is also effective in reducing the weight of the walking machine. Furthermore, since it is possible to reduce the reaction force from the floor surface at the time of landing and when leaving the floor surface, the load on the walking machine is reduced, so that the weight and the life of the walking machine can be reduced. Further, the floor reaction force applied at the time of landing and at the time of leaving the ground acts as a disturbance to the stability of the posture of the walking machine during walking. Therefore, reducing it allows the walking machine to walk stably. Also, when the walking machine loses stability during walking, the speed near the landing point of the foot and the floor departure point becomes smaller,
The impact caused by the collision between the floor surface and the foot is small, and then the trunk can be returned to a stable state.

In the above-described embodiment, the horizontal and vertical position speeds and accelerations of the foot during standing are matched with those at the time of swinging, but there is a method of determining the motion of the foot from the trajectory of the foot. is there. One of the measures is to move the locus of the foot along a part of the circumference of the ellipse. In this embodiment, the constitution of the motion locus generating unit 70 of the foot portion in the embodiment shown in FIG. 2 is possible by making it as shown in FIG. In FIG. 12, the same symbols as in FIG. 12 are the same parts. The swing leg foot position generating unit 700 is configured to set the swing leg motion, the horizontal and vertical position setting unit 710.
And a position condition for inputting and setting the values of the horizontal and vertical position of the foot portion at the time of switching between the standing state and the swinging leg state to the above-described foot movement during swinging leg and the horizontal and vertical position determining unit 710. A setting unit 711 and a position differentiating unit 712 that obtains speed by differentiating each position from the foot motion, horizontal and vertical direction position determining unit 710 when swinging a leg, and a foot motion, horizontal and vertical when swinging a leg. The foot motion during swinging, which determines the directional speed as a function of time, the horizontal and vertical speed determining unit 713, and the values of the horizontal and vertical speeds of the foot when switching between the standing state and the swinging state, Speed setting unit 714 for inputting and setting to the foot motion, horizontal and vertical direction speed determining unit 713 during the swinging leg
And a foot horizontal and vertical position determining unit 715 for swinging the foot to obtain horizontal and vertical positions of the foot. A running pattern parameter generation unit 80 is connected to the horizontal and vertical position determining unit 715 of the foot when swinging.

 Next, the operation of the above-described embodiment will be described.

The loci of movement of the feet 3F and 4F in this embodiment form a part of an ellipse, and an example thereof is shown in FIG. The movement of the body portion 2 is a constant velocity movement parallel to the floor surface as in the above-described embodiment. The walking cycle of one step is T seconds, and when standing and swinging
50% each. Then, when the ellipse shown in FIG. 13 is displayed by a parametric expression, x = Lcos ... (25) y = Rcos. Here, L represents the major axis of the ellipse, and R represents the minor axis. Then, with the change in the swinging leg being constant, the coordinate axes are set as shown in FIG. 13, and at time t = 0, the foot floor detachment operation starts from point 101, and The following equation shows the motion of the foot when the user makes a landing motion at point 103.

The calculation of the above equations (27) and (28) is performed by the foot movement and horizontal and vertical position determining portion 710 when swinging the leg.

Next, the speed of the foot is calculated by the position differentiator 712 (27).
Equation (28) is differentiated. The differential result is given by the following equation, and is set in the foot motion, horizontal and vertical direction speed determination unit 712 when swinging.

Here, L = S ₁ / cos θ (32) R = G / (sin θ + 1) (33) S ₁ is 1/2 of the stride H of the foot when the torso 2 is fixed
When the foot is described in the ground coordinate system, the step height H
1/4 of that. G is the height of raising the foot.

Here, θ is a constant that determines the point 103 on the arc of the ellipse.

Next, the foot motion during horizontal swing, horizontal and vertical speed determination unit 713 sets the setting condition from the speed condition setting unit 714, that is, t = 0. Under the condition that v _x = −v _B , the velocity is calculated so that the value of θ satisfies the following equation.

Next, the horizontal and vertical position determining unit 71 for the foot when swinging
In step 5, the position of the foot is calculated based on the expressions (27) and (28) described above. This calculation result is added to the leg drive control unit 5 by the same operation as in the above-described embodiment, and the walking legs 3 and 4 are
Walks.

Fig. 14 shows the trajectory of the foot with respect to the earth coordinate system. FIG. 15 shows the change of the horizontal position of the foot with time, FIG. 16 shows the change of the vertical position of the foot with time, and FIG. 17 shows the change of the horizontal speed of the foot with time. As can be seen from FIG. 17, the feet 3F and 4F have a horizontal velocity of zero when they leave the floor and land, and are connected to the stance movement.

In this embodiment, since the relative velocity with respect to the floor in the horizontal direction becomes zero at the moment when the feet 3F, 4F contact the floor surface, the impact force due to the floor surface contact can be suppressed. Further, as shown in FIG. 14, since the approach angles of the feet 3F, 4F with respect to the floor surface are configured to be larger, even if the body 2 is tilted and the landing time is delayed, horizontal displacement is small, It is possible to reduce the amount of dragging of the foot and the amount of horizontal internal force generated between the foot and the other foot that is standing.

〔The invention's effect〕

As described above, according to the present invention, when the free leg and the standing leg are switched, the acceleration component and the velocity component of the foot portion are continuous. The impact force between them can be suppressed to be small. As a result, the walking machine can be made to walk stably.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a walking machine provided with an embodiment of the device of the present invention, FIG. 2 is a diagram showing an example of the configuration of a motion locus generation unit of a foot constituting the device of the present invention, and FIG. FIG. 4 is a diagram showing a walking form of one walking leg in a walking machine, and FIG.
The figure which shows the horizontal direction acceleration change of the foot part of the walking leg in the example which is shown in the figure, the figure which shows the horizontal direction speed change of the foot part, the figure 6 which shows the vertical direction acceleration change of the foot part, 7th
Fig. 8 shows the vertical velocity change of the foot, Fig. 8 shows the horizontal position change of the foot, Fig. 9 shows the vertical position change of the foot, and Fig. 10 shows the ground coordinate system. Fig. 11 is a movement locus diagram of the foot in Fig. 11, Fig. 11 is a movement locus diagram of the foot in the body fixed coordinate system, and Fig. 12 is a configuration of another example of the movement locus generation unit of the foot constituting the device of the present invention. FIG. 13, FIG. 13 is a movement trajectory diagram of the foot in the body fixed coordinate system of the embodiment shown in FIG. 12,
Fig. 14 is a movement locus diagram of the foot in the earth coordinate system, Fig. 15 is a diagram showing a horizontal position change of the foot, Fig. 16 is a diagram showing a vertical position change of the foot, and Fig. 17 is a foot. It is a figure which shows the horizontal direction speed change of a part. 1 …… Walking machine, 2 …… Body, 3,4 …… Walking leg, 5 ……
Leg drive controller, 6 ... Motion locus generator.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuji Hosoda 502 Jinritsu-cho, Tsuchiura-shi, Ibaraki Hiritsu Seisakusho Co., Ltd.Mechanical Research Laboratory (72) Kazutoshi Suga, 502 Kintate-cho, Tsuchiura-shi, Ibaraki Hiritsu Seisakusho Co., Ltd. Inside the Mechanical Research Laboratory (72) Inventor Makoto Hattori 502 Jinritsucho, Tsuchiura City, Ibaraki Prefecture Hiritsu Mfg. Co., Ltd. Inside the Mechanical Research Laboratory (72) Inventor Yutaka Nakano 3-1-1 Sachimachi, Hitachi City, Ibaraki Hitachi Ltd. Hitachi Factory Examiner Shinichi Shimada (56) References JP 62-97006 (JP, A)

Claims (1)

[Claims] 1. A walking machine which controls an indirect portion of a walking leg by a leg drive control unit and walks by the walking leg,
A walking pattern parameter generating unit that specifies a stride length, a foot rising height, and the like, an acceleration condition setting unit that sets horizontal and vertical accelerations of the foot when switching between a standing state and a free leg state, and the walking Based on the data from the pattern parameter generation unit and the acceleration from the acceleration condition setting unit, the foot motion during swinging, horizontal and vertical accelerations are determined as a function of time. A directional acceleration determining unit, an acceleration integrator that obtains a velocity from each acceleration from the acceleration determining unit, and a velocity condition setting unit that sets horizontal and vertical velocities of the foot when switching between a standing state and a free leg state. And the speed from the speed condition setting unit and the speed from the acceleration integrator, the foot motion at the time of swinging, horizontal and vertical velocities are determined as a function of time. Section movement, horizontal and vertical speed determination unit, a speed integrator that determines the position from each speed from this speed determination unit, and horizontal and vertical position of the foot when switching between the standing state and the free leg state. At the time of swinging, the foot condition, horizontal and vertical position during swinging is determined as a function of time by the position condition setting unit to be set, the position from the velocity integrator and the position from the position condition setting unit. And a horizontal and vertical position determining unit, and a target joint angle calculating unit that calculates a target joint angle based on the position from the position determining unit and outputs the calculated target joint angle to the joint unit. Walking locus motion trajectory control device.