JP3148829B2 - Walking control device for legged mobile robot - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a walking control device for a legged mobile robot, and more particularly, to a walking control device capable of walking stably even when there is unexpected unevenness.

[0002]

2. Description of the Related Art As a legged mobile robot, for example, a bipedal walking robot disclosed in Japanese Patent Application Laid-Open No. 62-97006 is known.

[0003]

In the case of a legged mobile robot, particularly a bipedal legged mobile robot, when the joint is driven by displacement control, if the posture of the legged mobile robot leans forward at least during the period of supporting both legs, Since the rear foot separates from the floor and the entire load rides on the front foot, an extremely large restoring force is generated to return to the rear. In other words, if the restoring force per unit angle of the posture is referred to as a restoring force coefficient, it will have a very large restoring force coefficient during the two-leg supporting period, even if the posture stabilization control is not performed at all. Therefore, if the posture stabilization control that feeds back the inclination of the upper body (or the shift of the center of gravity) to the movement of the two legs is further added in such a state, the restoring force coefficient is further increased, and a sufficient restoring force coefficient corresponding to the restoring force coefficient Can not give any damping. As a result, the posture becomes rather unstable. By the way, when the joints are moved by torque control, appropriate compliance can be given to the legs.However, since the compliance characteristics corresponding to the relative position between the robot and the floor greatly change depending on the posture, it is necessary to deal with unevenness and inclination of the floor. The disturbance suppression characteristics do not match.

Accordingly, a first object of the present invention is to maintain a constant posture restoration coefficient without introducing a joint torque control which is difficult to be put into practical use due to the influence of friction and inertia of a joint portion, thereby enabling a robot to be fixed. A legged mobile robot that can approximate an inverted pendulum that always has a certain restoring force, can linearly approximate the control system, and can easily design a posture stabilization control law. It is to provide a walking control device.

Furthermore, even if there is unexpected unevenness or inclination, it is possible to walk while maintaining the inclination of the body with respect to the vertical direction substantially as designed, without being greatly affected by the irregularities and inclination. An object of the present invention is to provide a walking control device for a legged mobile robot.

Furthermore, in such a legged mobile robot, the robot walks while balancing the reaction force received from the floor with the resultant force of gravity and inertia acting on the floor from the robot side. If the impact force at the time is large, it becomes a cause of losing posture, and stable walking cannot be expected.

Accordingly, a third object of the present invention is to provide a walking control device of a legged mobile robot capable of walking in a stable posture by minimizing a landing impact received by the robot. It is in.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides, for example ,
And a walking control device for a legged mobile robot having a plurality of legs connected thereto via joints .
The floor reaction force acting on the bot is measured and the point of action, ZM
Detecting means for detecting the P actual measurement position, the detected ZMP
The measured position is compared with the target ZMP position, and the deviation is calculated.
ZMP deviation calculating means for calculating a first deviation, before Symbol upper body
Tilt angle and / or of the inclination oblique angle and / or detection hand <br/> stage for detecting the tilt oblique angular velocity, and the detected body
Compares the inclination angular velocity with the command value and compares the deviation with the second deviation
An inclined deviation calculating means, for determining a Rutotomoni, driving at least one of the legs of the joint of the leg portion of the plurality of such said <br/> first and second error obtained is reduced It was configured to.

[0009]

The leg is driven so that the inclination angle and / or angular velocity of the upper body coincides with the command value, so that the restoring force of the robot is made constant, that is, the robot always has a certain restoring force. It can be approximated by an inverted pendulum, and a linear control characteristic can be obtained. As a result, not only this stabilization control but also other types of stabilization control can be easily adopted. In addition, the posture as designed can always be maintained, and the landing impact can be effectively reduced.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below by taking a bipedal walking robot as an example of a legged mobile robot. FIG.
Is an explanatory skeleton diagram showing the robot 1 as a whole, and has six joints on each of the left and right leg links 2 (for the sake of convenience of understanding, each joint is shown by an electric motor that drives it). The six joints are, in order from the top, joints 10R and 10L for turning the hip leg (R is the right side and L is the left side).
The same applies hereinafter), joint 12 in the roll direction of the waist (around the x axis)
R, 12L, joint 14 in the same pitch direction (around the y axis)
R, 14L, knee joints 16R, 16L in the pitch direction,
The joints 18R and 18L in the pitch direction of the ankle part and the joints 20R and 20L in the same roll direction are attached below the feet 22R and 22L, and the uppermost part is the upper body (housing). 24, in which the control unit 2
6 is stored.

In the above, the hip joint is joint 10R (L),
12R (L) and 14R (L), and the ankle joint is composed of joints 18R (L) and 20R (L).
In addition, the thigh links 32R, 32 between the waist joint and the knee joint.
L, the lower leg links 34R, 34 between the knee joint and the ankle joint.
L connected. Here, the leg link 2 is given six degrees of freedom for each of the left and right feet, and by driving these 6 × 2 = 12 joints (axes) to appropriate angles during walking, the entire foot To a desired motion, and can be arbitrarily walked in a three-dimensional space. As described above, the above-mentioned joint is formed of an electric motor, and further includes a speed reducer for boosting the output thereof. Details of the joint are described in the application proposed by the present applicant (Japanese Patent Application No.
No. 324218, Japanese Patent Laid-Open No. 3-184787), and the like, which is not the subject of the present invention, and therefore, further description is omitted.

In the robot 1 shown in FIG. 1, a known six-axis force sensor 36 is provided at the ankle, and force components Fx, F in the x, y, and z directions transmitted to the robot through the foot.
y, Fz and moment components Mx, M around the direction
By measuring y and Mz, the presence or absence of landing on the foot and the magnitude and direction of the force applied to the supporting leg are detected. In addition, foot 22R
At the four corners of (L), a capacitance type ground switch 38 (FIG. 1)
(Not shown) is provided to detect the presence / absence of the touchdown of the foot. Further, a tilt sensor 40 is provided on the upper body 24, and x
The tilt with respect to the z-axis in the -z plane and its angular velocity, similarly y
-Detect the inclination with respect to the z-axis in the z-plane and its angular velocity. The electric motor of each joint is provided with a rotary encoder for detecting the amount of rotation. Further, although omitted in FIG. 1, an inclination sensor 40 is provided at an appropriate position of the robot 1.
Are provided with an origin switch 42 for correcting the output and a limit switch 44 for fail countermeasures. These outputs are sent to the control unit 26 in the body 24 described above.

FIG. 2 is a block diagram showing details of the control unit 26, which is constituted by a microcomputer. The output of the tilt sensor 40 and the like is converted into a digital value by the A / D converter 50, and the output is
Via the RAM 54. The output of an encoder disposed adjacent to each electric motor is input to the RAM 54 via a counter 56, and the ground switch 3
Outputs of the RAM 8 and the like are similarly sent to the RAM 5
4 is stored. In the control unit, there are provided first and second arithmetic units 60 and 62 each composed of a CPU. The first arithmetic unit 60 stores the characteristics of the trajectory of the waist posture stored in the ROM 64 as described later. The reference gait is generated by reading the parameters to be expressed, and then the target joint angle (joint drive pattern) is calculated and sent to the RAM 54. Further, the second arithmetic unit 62 reads out the target value and the detected actual value from the RAM 54 as described later, calculates a control value necessary for driving each joint, and outputs the control value via the D / A converter 66 and the servo amplifier. Output to the electric motor that drives each joint.

Next, the operation of the control device will be described.

FIG. 3 is a structured flow chart (PAD diagram) showing the operation. Referring to FIG.
First, in S10, the waist posture (that is, the inclination and direction of the waist) is calculated from the parameters representing the characteristics of the waist locus . Next, in S12, a ZMP target position derived from the equation of motion is calculated from the parameters representing the characteristics of the ZMP trajectory. (When the ZMP trajectory is represented by a polygonal line expression, the parameters representing the characteristics are also given by the folding point coordinates. Here, “ZMP” means a point on the floor where the moment due to the floor reaction force becomes zero. Next, in S14, the positions and postures of both feet are calculated from parameters representing the characteristics of the foot trajectory, for example, the landing position and the one-leg support period, and then in S16, the waist height that does not cause an unreasonable posture is determined. Then, the horizontal acceleration and the horizontal position of the waist are determined so that the ZMP becomes the target position . As described above , S10 to S18 show the work of creating the reference gait. In this embodiment, as described above, the parameters representing the characteristics of the trajectory of the waist posture are set in advance as data for each step. Then, the trajectories such as the waist, the ZMP, and the position / posture of the foot are calculated and used as a reference gait. As described later, the target angle of each joint is specifically calculated from the reference gait.

Next, the program proceeds to S20, where a leg compliance control value is calculated. FIG. 4 is a subroutine flowchart showing the operation.

Before starting the description according to FIG. 4, the compliance referred to in this embodiment will be described with reference to FIG.

As described above, if the force acting on the floor from the robot (the combined force of the robot's gravity and the inertial force) and the floor reaction force acting on the robot from the floor are balanced, the robot can walk stably. I do. If this is replaced with a concentrated load system, if the ZMP actual measurement position (the center point of the actual floor reaction force) matches the ZMP target position (the center point of the floor reaction force assumed by design values), the robot Walks while maintaining the posture as designed. Therefore, in the present invention, in the first embodiment, the floor reaction force applied to the rear foot and the floor reaction force applied to the front foot are measured from the six-axis force sensors 36 attached to both legs, and the resultant is the resultant force. A total measured floor reaction force is determined, and a ZMP measured position, which is the point of action, is determined and compared with a ZMP target position. Then, as shown in FIG. 6, if the measured ZMP position is shifted to the front (in this case, a moment is generated around the ZMP target position to tilt the robot backward) as shown in FIG. Lift the foot vertically (or lower the rear foot vertically depending on the amount of displacement, or lower the rear foot vertically while lifting the front foot vertically). By this operation, the floor reaction force applied to the front foot is relatively reduced as compared with the floor reaction force applied to the rear foot, so that the ZMP actual measurement position moves backward and the ZMP
Approach the target position. This control is referred to as “leg compliance control” in this specification. That is, in this specification, the leg compliance control means control for eliminating a deviation between the ZMP target position and the ZMP actual measurement position. Or Z
It can also be said that the control cancels the moment generated around the MP target position.

That is, when the robot walks in accordance with an ideal gait based on dynamics calculation, it is assumed that the robot slightly leans forward due to unexpected unevenness during the period of supporting both legs. If the leg compliance control described in this specification is not performed, the robot lifts its rear foot,
The entire load is applied to the front foot, and as a result, the floor reaction force action point (ZMP actual measurement position) shifts to the front foot sole. That is, the ZMP changes almost binaryly with respect to the inclination of the robot (FIG. 7). On the other hand, when the leg compliance control is performed, when the actually measured floor reaction force center (ZMP actual measurement position) is shifted forward from the designed floor reaction force center (ZMP target position), the front foot is lifted. Accordingly, the posture is such that both legs touch the ground while the upper body is tilted forward. At this time, the deviation between the measured ZMP position and the ZMP target position is proportional to the lifting height of the foot, and the lifting height of the foot is proportional to the inclination angle of the body. , The inclination angle of the upper body is also proportional. As will be described later, the proportional gradient is inversely proportional to the magnitude of the leg compliance, and the larger the amount of the leg compliance, the larger the proportional region with respect to the inclination angle of the robot (FIG. 8).

The leg compliance control is not limited to the two-leg support period, but may be performed during the one-leg support period. Also, as shown in FIG. 9, a shock absorbing mechanism such as a spring or rubber is provided below the ankle joint 18, 20R (L) to prevent oscillation of the leg compliance control and mechanically absorb the high frequency component of the load variation. It is desirable to insert it.

The calculation of the leg compliance control value will be described with reference to FIG.
At 00, the detection value of the six-axis force sensor 36 is fetched. Then
In S102, a ZMP actual measurement position is obtained. Referring to FIG. 10, the method will be described. A moment M → around an arbitrary origin is obtained, a force F → is obtained, and then M → =
The distance vector L → which is F → × L → is obtained, the object is translated in parallel by the distance L, and the intersection with the floor is obtained.

Next, the process proceeds to S104, where the ZMP actual measurement position and the ZMP target position are compared, and the deviation (the first
Is calculated. Specifically, the shift direction, that is, Z
When the MP actual measurement position is shifted from the ZMP target position,
It is determined whether it is shifted to the front side or to the rear side, and the difference (shift amount) x is calculated by the distance. Then S
A predetermined gain Kf and an actually measured floor reaction force F (or a vertical component (z direction) component F thereof) are added to the calculated difference x at step 106.
z) to obtain a foot posture correction amount (a method that does not multiply the floor reaction force may be used). That is, as described above , ZMP
If the measured position is shifted before the ZMP target position, FIG.
Although the moment generated around design floor reaction force central (ZMP target position) as shown in causes the rearward inclination of the robot, or raising the foot of the front leg vertically lowering the foot of the rear leg vertically Alternatively, the posture of the foot is corrected so that the foot of the front foot is raised vertically and the foot of the rear foot is lowered vertically, and the position of the foot is corrected according to the posture correction amount in S108. This causes a reverse moment,
That is, the ZMP actual measurement position can be brought closer to the ZMP target position, the balance of the posture can be restored, and the robot can walk in the posture as designed.
At this time, the posture correction amount (the lifting height of the foot) is shown in FIG.
As shown in, is determined in accordance with the deviation amount x, the deviation amount x posture correction amount since it is proportional to the inclination angle of the body is proportional to the inclination angle of the body. That is, assuming that the ratio between the posture restoring force of the robot and the inclination angle of the body is the posture restoring force coefficient of the robot, the posture correction amount is determined according to the inclination angle of the body,
The posture restoring force coefficient of the robot can be made as constant as possible. That is, the robot can always be approximated by an inverted pendulum having a constant restoring force coefficient, and a linear control characteristic can be obtained. Note that the posture correction direction is such that when the measured ZMP is shifted rearward from the design ZMP and a forward moment is acting on the robot, the driving direction of the foot is reversed and the foot of the rear foot is raised. Alternatively, the posture correction amount of the foot is determined so as to lower the foot of the front foot or to perform both of them .

Returning again to the flowchart of FIG. 3, the program proceeds to S22, in which the target angles of the twelve joints are obtained from the position and posture of the foot and the position and posture of the waist. still,
When the posture of the foot is corrected according to the flowchart of FIG. 4 in the calculation of the leg compliance control value in S20, the target angle is obtained based on the corrected posture. Then, the process proceeds to S24, where the inclination of the robot (the actual posture inclination angle and the actual posture inclination angular velocity) is determined from the output of the inclination sensor 40 described above.
Is detected, the deviation from the command value is calculated, and the deviation decreases .
To modify the target attitude so. A detailed description of this correction will be omitted. Then, the process proceeds to S26, in which the joint is controlled to follow the target angle. This is controlled by the second arithmetic unit 62 shown in FIG. 2, but since this control is not related to the gist of the present invention, detailed description is omitted.

[0024] Since this embodiment is configured as described above, determined
The plurality of pieces so that the first and second deviations are reduced.
Drives the joints of at least one of the legs
More specifically, the robot is moved to the corrected target posture.
To follow the joint displacement of the
The legs (more specifically) so that the second deviation is reduced.
Or the shock absorption mechanism shown in FIG.
And the floor has unexpected irregularities and Z
Even if the measured MP position deviates from the ZMP target position, the difference is effectively eliminated, and even if a moment is generated to overturn the robot around the ZMP target position,
It was constructed so as to cancel it. In other words, the robot can always be approximated by an inverted pendulum with a certain restoring force, so that the control characteristics can be made linear and the design of the control system becomes easy, and other posture stabilization control This facilitates the combination and facilitates stable walking even when unexpected irregularities are present on the floor. Also since the control to match the ZMP actual measurement position on the ZMP target position, landing impact is also reduced (where landing impact refers to large ones of the floor reaction force).

FIG. 11 shows a second embodiment of the present invention.
5 is a flowchart showing a leg compliance control value calculation subroutine similar to FIG. 4. Explaining focusing on the differences from the first embodiment, the shift direction and the shift amount x are obtained (S200 to S204), and then the process proceeds to S206, as shown at the end of FIG. As shown in the figure, the coordinate rotation angle when assuming that the floor is tilted while keeping the constant is obtained as shown in the figure, and the process proceeds to S208, and the position and posture of both feet are rotated around the ZMP target position by the rotation angle described above. To correct. Here, the floor inclination angle θ is determined by θ = shift amount x gain Kf.

In this embodiment, when the measured ZMP position is shifted forward as shown at the end of FIG. 6, the foot on the rear side strongly kicks the actual floor (shown by the solid line). A floor reaction force is generated, and the measured ZMP position can be brought closer to the ZMP target position. That is, also in this case, a moment in the opposite direction to the moment shown in the upper part of FIG. 6 can be generated, and the posture can be prevented from being collapsed. Also in this embodiment, a restoring force proportional to the amount of displacement can be provided. That is, a linear control characteristic can be obtained with a constant restoring force coefficient.

FIG. 12 is a flow chart similar to FIG. 3 but showing a third embodiment of the present invention. The following description focuses on the differences from the first embodiment (or the second embodiment). In this embodiment, after calculating the leg compliance control values in S300 to S306, the process proceeds to S308, and the posture is not excessive. The height of the waist in the vertical direction (z direction) is obtained, and then the process proceeds to S310, where the leg compliance control is performed to correct the foot position and posture, so that the horizontal acceleration and the horizontal position of the waist are set so that the ZMP is at the target position. And S
Proceeding to 312, a target joint angle is determined based on the foot position / posture and the waist position / posture (correction values when corrected in the subroutine of S306). The remaining configuration including S314 and S316 is not different from the first embodiment (or the second embodiment).

That is, the leg compliance control is performed mainly to prevent the measured ZMP position from deviating from the ZMP target position even if there is disturbance due to unevenness or inclination of the floor. It is also desirable that the ZMP target position itself does not shift. That is, only by correcting the foot posture by leg compliance control, Z
The MP measurement position can be returned to the ZMP target position,
As a result, the posture of the body may change, and the ZMP target position itself may deviate from the expected position. Here, if the mass of the legs, especially the mass of the tip, is sufficiently smaller than that of the upper body, the deviation of the design ZMP position can be ignored, and the horizontal position of the upper body can be the same as the reference gait. In the configuration shown in FIG. 1, it is difficult to say that the mass of the foot 22 is sufficiently smaller than that of the upper body 24, but the first embodiment (or the second embodiment)
In the case of Example), the effect on the upper body caused by performing the leg compliance control was considered to be substantially very small, and was ignored. On the other hand, in the third embodiment, as shown, the horizontal position and acceleration of the body are corrected. Therefore, in addition to the effects of the first embodiment (or the second embodiment), there is an effect that the posture can be stabilized more precisely. In the third embodiment, the correction of the waist height in the vertical direction in S308 may not be performed.

[0029] Incidentally, the smaller the leg compliance operation, may be transferred to the leg compliance control value calculation subroutine gait generator 2 during or subsequently. In doing so, the calculations of the gait generator 1 and the gait generator 2 can be performed off-line in advance, which is convenient when using a computer with low computational power.

FIG. 13 shows a fourth embodiment of the present invention. Similar to FIG. 4 (first embodiment) and FIG. 11 (second embodiment), a subroutine flow chart relating to leg compliance control value calculation is shown. It is. Referring to the figure, after the values detected by the six-axis force sensor are taken in S400, the flow proceeds to S402 to obtain the moment actually generated around the ZMP target position, and proceeds to S404 to obtain the actual moment and the moment command. The difference from the value (usually set to zero) is obtained, and the process proceeds to S406 and S408, where the deviation is multiplied by the gain as in the second embodiment to obtain the coordinate rotation angle. I asked for.

The fourth embodiment differs from the previous embodiment in the method of decomposing the measured floor reaction force. That is, while the previous embodiment focuses on the action point position when the floor reaction force is decomposed by a vector of only a force without a moment, in the fourth embodiment, the value applied to the ZMP target position is defined as the force and moment. It focuses on the moment when it is decomposed into, and in that sense, it is not essentially different from the conventional detection method.

In the fourth embodiment, the target joint angle is calculated after calculating the leg compliance control value in accordance with the subroutine flowchart of FIG. 13. In this case, FIG. 3 of the first embodiment is used. As shown, the position / posture of the body may not be corrected, or the position / acceleration of the body in the horizontal direction may be corrected as shown in FIG. 12 of the third embodiment. As an effect of the fourth embodiment, since the leg compliance control value is determined by directly detecting the moment around the ZMP target position, a more linear and stable posture control is realized as compared with the previous embodiment. Can be.

The fourth embodiment will be described with reference to a flat gait based on the block diagram of FIG.
If the gait is on the slope of 1, the following description will show Δθ and Δθ
comm may be replaced by θ1 + Δθ and θ1 + Δθcomm). In the figure, a so-called reverse kinematics calculation unit that calculates the displacement of each joint from the set position and posture calculates the posture when the floor is inclined by Δθcomm in the reference gait. Fig. 1
The robot joint displacement shown in (1) follows the posture command issued from the inverse kinematics calculation unit. The robot illustrated in FIG. 1 assumes that perfect rigid body, and have One the attitude obtained from the actual joint displacement, robots and foot ground surface tangent (A in FIG.
(A dash line) is defined as Δθ. Is sufficiently high follow-up performance of the displacement controller, is Δθ Δ θ com
matches m. In this case, the transfer function G from the robot and the relative angle of the floor, to a floor reaction force actual moment M about the ZMP target position is as shown in Equation 1.

[0034]

(Equation 1)

This is because, as shown in FIG.
It is equivalent to a bending spring of (1 / Kleg + Kf).

In the fourth embodiment, when a moment is generated around the target ZMP position due to the robot stepping on unexpected irregularities or the like, the moment is directly detected and coordinate rotation is performed in proportion to the magnitude of the moment. The angle is virtually obtained, and the position / posture of the foot is set to the target ZM by the virtual angle.
Correct to rotate around P position, ie, target Z
Directly detecting the moment generated around the MP position,
Since a moment in the opposite direction is generated around the same position so as to cancel this, as described above, the linearization of the control characteristic and the posture are further achieved as compared with the first to third embodiments. Can be realized. Furthermore,
When correcting the position / acceleration of the upper body in the horizontal direction in the same manner as shown in FIG. 12, the linearization of the control characteristics and the stabilization of the posture can be achieved even more accurately.

Since the ZMP target position moves continuously or intermittently, for a gait in which the ZMP target position moves rapidly, the moment calculation center and the rotation center of the leg compliance operation are set to the ZMP target position. In such a case, a sudden change in the behavior is likely to occur, and there is a possibility that the user cannot stably walk due to bouncing or the like. Therefore,
For such a gait, the moment calculation center and the rotation center of the leg compliance operation are close to the ZMP target position but move more gently, for example, a point where the ZMP target position is filtered and smoothed. Is good.

FIG. 16 is a flow chart showing a leg compliance control value calculation subroutine similar to that of FIG. 13 of the fourth embodiment, showing a fifth embodiment of the present invention. Instead of the ZMP target position, a reference point,
For example, ankles of supporting legs (ankle joints 18, 2 in FIG. 1)
The moment around the point of projection of 0R (L) on the floor is determined, and the moment is rotated around that point (S5).
02, S508). The rest of the configuration including the other steps is the same as in the fourth embodiment, and whether or not the body is modified is also the same as in the fourth embodiment. The floor reaction force moment is slightly easier to obtain, but the effect is the same as that of the fourth embodiment except that the control value is slightly inferior to that of the fourth embodiment. Note that the reference point may be a moving point.

FIG. 17 shows the sixth embodiment. The difference from the previous embodiment is that if the foot farther from the ZMP target position is moved violently, the legs may oscillate. As shown in FIG. 18, the movement angle θ1 of the foot on the far side on the rotational coordinate is smaller than that of the foot on the near side θ2. Although the driving method of the foot is in accordance with the second embodiment, the vertical movement of the first embodiment is also appropriate, and the upper body may or may not be modified.

FIG. 19 shows a seventh embodiment of the present invention, which deals with a case where a lateral overturning force is applied in the traveling direction. That is, in the previous embodiment, the control value was calculated by detecting the traveling direction, that is, the moment My acting around the y-axis, but in this embodiment, the moment in the lateral direction (around the x-axis) was calculated. Mx is also detected to calculate the control value (S700 to S708). The second
Although described according to the embodiment, this technique is also applicable to other embodiments. Although the moment was used, the lateral force F
y may be used.

FIG. 20 shows an eighth embodiment of the present invention. In the block diagram of FIG. 14 showing the fourth embodiment, a filter 80 is interposed between the robot main body and the floor. . For example, the transfer function of this filter is 1 /
(1 + TS) (where T is a time constant). Assuming that the followability of the displacement controller is sufficiently high, Δθ is Δθco
mm. Accordingly, the transfer function G from the relative angle between the robot and the floor to the actual floor reaction force moment M around the ZMP target position is as shown in Expression 2.

[0042]

(Equation 2)

If the leg rigidity Kleg is sufficiently high, 1 / Kl
eg can be ignored, and the equation becomes as shown in Equation 3.

[0044]

(Equation 3)

This is equivalent to a mechanism in which a torsion spring and a torsion damper are assembled in parallel as shown in FIG. That is,
A damping effect equivalent to inserting a mechanical damper between the robot body and the floor can be obtained, and jumping when the free leg lands can be prevented. Further, since such a low-pass filter is inserted into the feedback loop of the compliance control, as a secondary effect, the loop gain for high frequencies can be reduced, the stability of the compliance control system can be increased, and oscillation can be prevented. In addition, high frequency noise entering from the six-axis force sensor 36 can be removed.

FIGS. 22 to 28 show a ninth embodiment of the present invention.

In a legged mobile robot, when the joint is driven by displacement control, if the above-described leg compliance control is not performed, and if the posture leans forward even a little during the two leg support period during walking, the rear foot Since the flat is off the floor and the entire load is on the front foot, an extremely large restoring force is generated to return to the rear. That is, the above-mentioned restoring force coefficient becomes extremely large during the two-leg supporting period. Therefore, if the posture stabilization control that feeds back the inclination of the body or the shift of the center of gravity to the movement of the two legs in such a state is further performed, the restoring force coefficient is further increased, and a sufficient damping effect corresponding thereto can be provided. become unable. As a result, the posture becomes rather unstable. Therefore, in this embodiment, the posture stabilization control is performed according to the inclination of the body while performing the leg compliance control described above. In addition, instead of performing the leg compliance described above, compliance can be given to the leg by driving the joint by torque control.However, the compliance characteristic corresponding to the relative position between the robot and the floor greatly depends on the posture. Therefore, the disturbance suppression characteristics for unevenness and inclination of the floor do not match.

The ninth embodiment will be described below with reference to the flowcharts of FIGS.

FIG. 22 is a view for explaining the third embodiment shown in FIG.
2 is the same main routine flow chart as that of FIG. 2 except that in S810, not only the leg compliance control value but also the stabilization control value is calculated. FIG. 23 is a subroutine flow diagram showing the operation.
Is a chart showing the difference between the actual moment and the command value (see above).
(First deviation) obtained (S900-S904), then S
At 906, a stabilization control value is obtained by multiplying a predetermined gain by a deviation (the above-described second deviation) between the actual inclination angle, the inclination angular velocity, and the command value of the body, and adds the result to the leg compliance control value. calculated coordinate rotation angle Te, and so as to modify its value in S908. In this way, it has to be directed to the same joints stabilization control value and the leg compliance control value, and controls the easily.

FIG. 24 is a block diagram showing this.
As shown, the posture stabilization control of the upper body is performed using PD control. Here, as described above, Δθ is Δθcom
m, and assuming that the measured ZMP position matches the ZMP target position, FIG. 24 can be modified as shown in FIG. As is clear from FIG. 25, the total system including the robot and the control system is linear, and
Various linear control theories such as classical control theory, optimal control theory, and robust control theory can be applied to the attitude tilt stabilization control. FIG. 26 shows an example using the state feedback control.

In the ninth embodiment, since the configuration is as described above, the first and second deviations obtained are reduced.
At least one of the plurality of legs
Drive the joints, more specifically, the corrected target posture
Follow the joint displacement of the robot.
Said legs so that the first and second deviations are reduced.
Elastic deformation of the part (more specifically, the shock absorbing mechanism shown in FIG. 9)
Will be generated stress due to, without using a practical use is difficult to joint torque control by the effect of wear and inertia of the joint portion, it is possible to realize a posture stabilization control.
That is, if the displacement of both feet is intentionally shifted from the design value, the leg compliance control generates a posture restoring force corresponding to the shift amount. Therefore, in the posture stabilization control based on the body tilt feedback, the displacement of both feet can be used as the operation amount in order to generate the restoring force. Also, regardless of whether it is a single leg support period or a double leg support period,
Since the posture restoring force coefficient of the robot can be kept almost constant, the robot can always be approximated as an inverted pendulum with a certain restoring force, and the control system can be linearly approximated, and the posture stabilization control law Can be easily designed.
Also, even if there is unexpected unevenness or inclination on the floor, it is possible to walk while maintaining the inclination of the upper body with respect to the vertical direction almost as designed, without being affected so much.

Here, the same configuration as that described in the eighth embodiment can be applied to the filter 800 shown in FIG. 25 as will be described later. Add consideration. That is, if attention is paid to the dynamic characteristics of the control system and the compliance control is summarized by regarding the floor reaction force moment command as 0, FIG. 25 can be modified as shown in FIG. FIG. 27 is equivalent to the inverted pendulum having the spring and the actuator shown in FIG. This simplification enables not only the application of various linear control theories, but also the inference of robot attitude control from the behavior of a simple model. The best combination of properties can be easily found without much experimentation and simulation. Needless to say, the filter 800 may have a damping effect equivalent to a mechanical damper, as in FIG. That is, in the posture control for feeding back the inclination angle of the body, FIG.
As shown in, the inclination angle velocity of the body (or the inclination angle of the straight line connecting the ground point and the center of gravity) is also fed back in order to enhance stability. However, due to insufficient link system rigidity and insufficient gait, etc. When the body vibrates at a high frequency, a large high-frequency fluctuation occurs in the tilt angular velocity. Therefore, when the tilt angular velocity feedback gain is increased, the legs may vibrate or oscillate. Therefore, if the same filter as that used in the eighth embodiment is used, the stability of the attitude control system can be increased by supplementing the tilt angular velocity feedback. Stability can be ensured. The effect of preventing jumping when the free leg lands is the eighth effect.
This is the same as the embodiment.

Although various examples have been shown in the above embodiment, the modifications are not limited thereto. That is, in this control, the following are arranged. Detection target a. Amount of deviation between ZMP target position and ZMP actual measurement position b. Moment of force generated by floor reaction force around ZMP target position c. 1. Moment of force generated by floor reaction force around reference point Foot movement a. Up and down one leg b. Upper and lower legs c. Foot rotation d. 2. Reduce the amount of movement of the foot farther from the ZMP target position than that of the other foot. Horizontal movement of upper body a. Maintain reference gait b. 3. Correct position and acceleration in the horizontal direction. Vertical movement of upper body a. Maintain reference gait b. 4. Recalculate waist height Upper body posture stabilization control a. No b. However, all of these can be combined, and the examples are only examples.

In the above description, an example is shown in which the present invention is applied to the case where the walking data is set in advance. However, the present invention is not limited to this, and the present invention may be applied to a technique in which the walking data is obtained in real time.

In the above description, a legged mobile robot that walks on two legs has been described as an example. However, the present invention is not limited to this, and is applicable to a legged mobile robot having three or more legs.

[0056]

According to the first aspect, the upper body 24,
And a plurality of legs connected to it via joints (leg
In the walking control device of the legged mobile robot 1 having the link 2) , the floor reaction force acting on the robot is measured, and the
Detecting means for detecting the ZMP actual measurement position as the action point (6-axis force
Sensor 36, control unit 26, S20, S306, S
100, S102, S200, S202), the detected
Comparing the measured ZMP actual position with the target ZMP position,
The deviation (deviation direction, deviation amount X) is obtained as a first deviation.
ZMP deviation calculating means (control unit 26, S20,
S306, S104, S204), inclined obliquely angle of the upper body
And / or detecting means for detecting an inclination oblique angular velocity (gradient Se
Capacitors 40, the control unit 26), and the detected
Inclination deviation calculating means (control units 26, S24, S314) for comparing the inclination angle and / or the inclination angular velocity of the body with the command value and obtaining the deviation as a second deviation.
And the obtained first and second deviations decrease.
It said plurality of legs, at least one of the legs of the joint of the (10~20R, L) to drive (electric motor as
Data, control unit 26, S24, S26, S314, S
316), the displacement of the leg joint can be used as the operation amount in order to generate the restoring force in the posture stabilization control by the body tilt feedback, and the influence of the wear and inertia of the joint portion can be used. Accordingly, the control system can be linearly approximated without introducing joint torque control which is difficult to put into practical use, and posture stabilization control can be easily realized. In addition, when unexpected irregularities are encountered, the collapse of the posture can be suppressed as much as possible, the posture as designed can be maintained, and the impact at the time of landing can be effectively absorbed.

[0057] In the second aspect, wherein, the body 24, it
Multiple legs (leg links) connected to the
In the walking control device of the legged mobile robot 1 including 2)
A desired gait generator for generating a desired posture of the robot
Stage (control unit 26, S10 to S18, S300 to S
304, S308, S310), acting on the robot
Floor reaction force to detect the ZMP actual measurement position
Detecting means (6 axis force sensor 36, control unit 2
6, S20, S306, S100, S102, S20
0, S202), target the detected ZMP actual measurement position
And the deviation (shift direction, shift)
ZMP deviation calculating means for obtaining the amount X) as the first deviation
(Control unit 26, S20, S306, S104, S
204), the inclination angle and / or inclination angle speed of the body
Detecting means (inclination sensor 40, control unit
26), the detected inclination angle of the upper body and / or
The inclination angular velocity is compared with the command value, and the deviation is compared with the second deviation.
Deviation calculating means (control unit 26, S2
4, S314), and the determined first and second
Target posture correcting means for correcting the target posture according to the deviation of
Stage (control unit 26, S24, S26, S314, S
316), and the target posture correcting means includes:
Follow the joint displacement of the robot to the corrected target posture
And thus the first and second deviations obtained are reduced.
In order to reduce the stress generated by the elastic deformation of the legs,
It was that (electric motor, the control unit 26, S24, S2
6, S314, S316) , the body tilts
Restoring force in attitude stabilization control by oblique feedback
In order to generate the displacement, the amount of displacement of the leg joint is
Can be used, depending on the wear of the joints and the effect of inertia.
Without introducing joint torque control that is difficult to
The control system can be linearly approximated, and posture stabilization control can be performed.
It can be easily realized. Also encounter unexpected irregularities
The design value can be minimized when the posture collapses
The street posture can be maintained, and the impact at the time of landing can be effectively absorbed.

[0058] In the third aspect, wherein, the body 24, it
Multiple legs (leg links) connected to the
In the walking control device of the legged mobile robot 1 including 2)
A desired gait generator for generating a desired posture of the robot
Stage (control unit 26, S10 to S18, S300 to S
304, S308, S310, S80-S808), before
Floor reaction force around a predetermined reference point acting on the robot.
Floor reaction force moment detection means (6-axis force
Sensor 36, control unit 26, S20, S306, S
810, S400, S402, S500, S502, S
600, S602, S700, S702, S900, S
902), the detected floor reaction force moment is targeted.
And the deviation is referred to as the first deviation.
For calculating the floor reaction force moment deviation (control unit
G26, S20, S306, S810, S404, S5
04, S604, S704, S904), the inclination of the upper body
Detecting means for detecting a tilt angle and / or a tilt angular velocity
(Tilt sensor 40, control unit 26)
The tilt angle and / or tilt angular velocity of the upper body
Comparing and calculating the slope deviation as a second deviation
Delivery means (control unit 26, S24, S314, S81
0, S906), and the determined first and second
Target posture correcting means for correcting the target posture according to the deviation of
Stage (control unit 26, S24, S26, S314, S
316, S810, S814, S906, S908),
And the target posture correcting means performs the correction.
The joint displacement of the robot follows the target posture
So that the first and second deviations determined above are reduced.
To, Ru cause stress due to the elastic deformation of the leg portions (Electric
Motor, control unit 26, S24, S26, S31
4, S316, S814, S816), the posture stabilization control by the body tilt feedback is performed.
In order to generate restoring force, the amount of operation
The amount of shift can be used, and the wear and inertia of the joints
Introduce joint torque control that is difficult to put into practical use due to its influence
The control system can be linearly approximated without any
Control can be easily realized. Also unexpected
Even when bumps and valleys are encountered, the posture can be minimized.
Can maintain the posture as designed,
The impact of landing can be effectively absorbed to Rukoto.

According to a fourth aspect of the present invention, the target posture correction
Means are proportional to the determined first and second deviations.
Owing to this configuration to modify the target attitude Te, the design value communication
Posture while maintaining linear control characteristics.
Properties can be obtained, and the impact at the time of landing can be absorbed .

According to a fifth aspect of the present invention, the predetermined reference point
Since There were composed as a ZMP position a target, more
The posture as designed can be secured, and linear
Control characteristics can be obtained, and the impact at the time of landing can be absorbed .

According to a sixth aspect of the present invention, the target posture correction
The means may include a tip of one of the plurality of legs.
By correcting the target position and / or posture of (foot)
The target posture is modified so that it is relatively simple
Posture and linear control characteristics according to the design values
The impact can be secured, and the landing impact can be absorbed .

According to a seventh aspect of the present invention, the target posture correction
The means comprises a target position and / or posture of the tip of the leg.
Is modified by moving the leg in the vertical axis direction.
Fruit can be obtained. In claim 8,
The target posture correcting means may be configured such that the tip of the leg portion
Without changing the relative position, the posture when the floor is virtually tilted
By doing so, it was configured to correct the target posture,
Simply take the posture when you virtually tilt the floor,
The effects described above can be obtained. Also, in claim 9
If so, the target posture correction means is provided when the floor is tilted.
The rotation center is set to the ZMP target position or a predetermined reference point.
The center of rotation can be matched with the detection point.
Can achieve the above-mentioned effects more accurately.
You. According to a tenth aspect, the target posture correction is performed.
The means is a rotation angle of the tip of the leg remote from the rotation center.
Make the degree smaller than that of the tip of the leg on the near side
Configuration, so that unnecessary oscillation of the legs may occur.
The above-described effect can be obtained without fear of the risk. Also,
In the eleventh aspect, the target posture correcting unit is configured to
Maintain body position and / or posture in target posture
The target position and / or posture of the tip of the leg
Is modified so that it is a simple method.
Thus, the above-described effects can be obtained. Claim 1
In the second aspect, the high frequency component of the detected value is provided to the detecting means.
Configured to connect filters 80 and 800 for attenuating noise
Therefore, it is possible to prevent the occurrence of jumping when the free leg lands, and also to increase the stability of the control system to prevent its oscillation, and furthermore, noise enters the detection means. Sometimes, it can be prevented well.

[Brief description of the drawings]

FIG. 1 is a schematic view showing the entire walking control device of a legged mobile robot according to the present invention.

FIG. 2 is an explanatory block diagram of a control unit shown in FIG.

FIG. 3 is a main diagram showing the operation of the control unit shown in FIG. 2;
It is a flow chart.

4 is a flowchart showing a leg compliance control value calculation subroutine in the flowchart of FIG. 3;

FIG. 5 is an explanatory diagram illustrating leg compliance control of FIG. 4;

FIG. 6 is a diagram for explaining the leg compliance control of FIG. 4 and is an explanatory diagram showing a driving method of the leg.

7 is a graph showing a relationship between a deviation amount between a ZMP target position and a ZMP actual measurement position in the leg compliance control of FIG. 4 and a tilt angle of the robot.

8 is a graph showing a relationship between a deviation amount between a ZMP target position and a ZMP actual measurement position in the leg compliance control of FIG. 4 and a magnitude of a leg compliance control value.

FIG. 9 is an explanatory diagram showing a foot structure of a robot suitable for the leg compliance control of FIG. 4;

FIG. 10 is an explanatory diagram showing a method of detecting a ZMP actually measured position in the leg compliance control of FIG. 4;

FIG. 11 is a flowchart showing another example of leg compliance control value calculation according to the second embodiment of the present invention.

FIG. 12 is a flowchart showing an example in which the body position is re-corrected together with leg compliance control according to the third embodiment of the present invention.

FIG. 13 is a flowchart showing another example of leg compliance control value calculation according to the fourth embodiment of the present invention.

FIG. 14 is a block diagram illustrating a fourth embodiment.

FIG. 15 is a diagram schematically illustrating the robot shown in FIG. 14;

FIG. 16 is a flowchart showing another example of leg compliance control value calculation according to the fifth embodiment of the present invention.

FIG. 17 is a flowchart showing another example of leg compliance control value calculation according to the sixth embodiment of the present invention.

FIG. 18 is an explanatory diagram illustrating control of a sixth embodiment.

FIG. 19 is a flowchart showing another example of leg compliance control value calculation according to the seventh embodiment of the present invention.

FIG. 20 is a block diagram showing a state where a filter is interposed in a control loop according to an eighth embodiment of the present invention.

FIG. 21 is an explanatory diagram for mechanically explaining the characteristics of the filter of FIG. 20;

FIG. 22 is a flowchart showing control in which another stabilization control is combined with leg compliance control according to a ninth embodiment of the present invention.

FIG. 23 is a flow chart showing a control value calculation subroutine of leg compliance control and stabilization control in the flow chart of FIG. 22;

FIG. 24 is a block diagram illustrating a ninth embodiment.

FIG. 25 is a block diagram showing a simplified modification of the block diagram of FIG. 24;

FIG. 26 is a block diagram showing an example in which the ninth embodiment is implemented by a state feedback control method.

27 is a block diagram showing an example in which the block diagram of FIG. 25 is modified by setting the transfer characteristic of the filter to 1;

FIG. 28 is an explanatory diagram showing FIG. 27 by replacing it with a mechanical configuration.

[Explanation of symbols]

Reference Signs List 1 legged mobile robot (bipedal walking robot) 2 leg link 10R, 10L leg rotation joint 12R, 12L crotch roll direction joint 14R, 14L crotch pitch direction joint 16R, 16L knee joint Joints in the pitch direction 18R, 18L Joints in the pitch direction of the ankle 20R, 20L Joints in the roll direction of the ankle 22R, 22L Foot 24 Upper body 26 Control unit 36 6-axis force sensor 80, 800 Filter

Continuation of the front page (56) References JP-A-3-161290 (JP, A) JP-A-6-211177 (JP, A) JP-B-48-39425 (JP, B1) Miomir Vukobratovic, translated by Ichiro Kato , "Walking Robots and Artificial Feet", Nikkan Kogyo Shimbun, March 31, 1975, p. 121-178 (58) Field surveyed (Int. Cl. ⁷ , DB name) B25J 5/00 B25J 13/00, 13/08

Claims (12)

(57) [Claims] 1. An upper body and a joint connected thereto via a joint.
A walking control device for a legged mobile robot having a plurality of legs, comprising: a . Measure the floor reaction force acting on the robot and its action
Detecting means for detecting a measured ZMP actual position ; b . ZMP targeting the detected ZMP actual measurement position
ZM which is compared with the position and the deviation is obtained as a first deviation
P deviation calculating means, c . Detecting means for detecting an inclination oblique angle and / or tilt the swash angular velocity of the previous SL upper body, and d. The detected tilt angle and / or tilt of the upper body
The angular velocity compared with the command value, slope deviation calculating means for calculating <br/> using the deviation as a second difference, the provided Rutotomoni, the first and second deviation reduction obtained
Walk controller of a legged mobile robot, wherein at least Turkey to drive one of the legs of the joint line of the plurality of legs so that little. 2. The upper body is connected to the upper body via a joint.
Walking control device for legged mobile robot with multiple legs
In a . A desired gait generator for generating a desired posture of the robot
Steps, b . Measure the floor reaction force acting on the robot and its action
Detecting means for detecting a measured ZMP actual position ; c . ZMP targeting the detected ZMP actual measurement position
ZM which is compared with the position and the deviation is obtained as a first deviation
P deviation calculating means, d . Detecting the tilt angle and / or tilt angular velocity of the body
Issuing detection means, e . The detected tilt angle and / or tilt of the upper body
Compare the angular velocity with the command value and use the deviation as the second deviation
Means for calculating the inclination deviation to be obtained, and f . According to the determined first and second deviations,
Target posture correcting means for correcting a target posture , and wherein the target posture correcting means corrects the target posture.
The joint displacement of the robot follows the target posture
So that to reduce the first and second deviations obtained the Te
Generating a stress due to elastic deformation of the legs.
A walking control device for a legged mobile robot. 3. The upper body is connected to the upper body via a joint.
Walking control device for legged mobile robot with multiple legs
In a . A desired gait generator for generating a desired posture of the robot
Steps, b . Floor around a predetermined reference point acting on the robot
You detect a reaction force moment floor reaction force moment detecting means, c. The floor reaction force which is the target of the detected floor reaction force moment.
Force moment, and determine the deviation as the first deviation.
Means for calculating the floor reaction force moment deviation, d . Detecting the tilt angle and / or tilt angular velocity of the body
Issuing detection means, e . The detected tilt angle and / or tilt of the upper body
Compare the angular velocity with the command value and use the deviation as the second deviation
Means for calculating the inclination deviation to be obtained, and f . According to the determined first and second deviations,
Target posture correcting means for correcting a target posture , and wherein the target posture correcting means
The joint displacement of the robot follows the target posture
So that the first and second deviations determined above are reduced.
Generating a stress due to elastic deformation of the legs.
A walking control device for a legged mobile robot. 4. The method according to claim 1, wherein the desired posture correcting means is configured to determine the desired posture.
Correcting the target attitude in proportion to the first and second deviations
The leg type according to claim 2 or 3, wherein
Walking control device for mobile robots. 5. The method according to claim 1, wherein the predetermined reference point is a target ZMP position.
The device according to claim 3 or 4, wherein
A walking control device for a legged mobile robot. 6. The target posture correcting means includes a target position and / or a target position of a tip of one of the plurality of legs.
The walking control device for a legged mobile robot according to any one of claims 2 to 5 , wherein the target posture is corrected by correcting the posture . 7. The method according to claim 7, wherein the target posture correcting means is provided at a tip of the leg.
Correct the target position and / or attitude of the end in the vertical
It is carried out by moving the walk controller of a legged mobile robot according to claim 6 wherein wherein the. Wherein said target position modifying means, without changing the relative position with respect to the floor of the tip of the front Kiashi portion, to correct the target position by the posture when tilted virtually bed The walking control device for a legged mobile robot according to claim 6, wherein : Wherein said target position modifying means, the legs of claim 8 wherein wherein the center of rotation and the ZMP target position or wherein the predetermined reference point <br/> and to Turkey when tilting the bed Walking control device for mobile robots. 10. The apparatus according to claim 7, wherein the target posture correcting means is configured to rotate the target posture.
Rotate the rotation angle of the tip of the leg far from the
Specially, make the correction smaller than that of the tip.
10. The walking control of a legged mobile robot according to claim 9, wherein
apparatus. 11. The target posture correcting means includes : the target posture
While maintaining the position and / or posture of the upper body in the force,
Correct the target position and / or posture of the tip of the leg
The method according to any one of claims 2 to 10, wherein
The walking control device of the legged mobile robot according to the above. 12. A said detecting means, the legged mobile robot according to claim 1 wherein 11 wherein, wherein the benzalkonium connecting a filter that attenuates high frequency components <br/> detection value Walking control device.