JPH0631658A - Walk control device for leg type moving robot - Google Patents

Abstract

PURPOSE:To stabilize walk by obtaining an angle of a floor surface supposed by target walk capacity and an actual floor surface as a difference between a virtual plane and a supposed floor obtained by assuming no action by compliance, estimating reaction force according to a predetermined characteristic, and correcting the target walk capacity by a difference from actual floor reaction force. CONSTITUTION:An estimated tilt of a virtual plan of including an tread expected location is obtained through kinematics calculation from an attitude tilt detection value and an articulated displacement detection value of a robot detected by a tilt sensor. Next, a difference from an estimated floor surface tilt is obtained to estimate an estimated interference angle. Based on a compliance model from this estimated interference angle, estimated floor reaction force moment is obtained. From a difference between actual floor reaction force moment, obtained from a 6-shaft force sensor and a processing arithmetic device, and the estimated floor reaction force moment, a floor surface tilt estimated deviation is obtained by a correction rule, to correct an interference angle in an ideal condition, calculate the attitude tilt detection value processed, obtain an interference angle command value and to correct target walk capacity by reverse kinematic calculation.

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 specifically, it estimates the inclination angle of an actual floor surface and calculates the deviation from the inclination angle of the floor surface assumed in a desired gait. The present invention relates to the one in which the posture is corrected so as to cancel the floor reaction force deviation caused by the deviation.

[0002]

2. Description of the Related Art As legged mobile robots, particularly bipedal legged mobile robots, those described in JP-A-62-97005 and JP-A-63-150176 are known. For details on the control of robots including legged mobile robots, see "Robot Engineering Handbook" (edited by the Robotics Society of Japan, October 20, 1990).

[0003]

By the way, the posture of a legged mobile robot, particularly a bipedal legged mobile robot, tends to be inherently unstable. Therefore, the present applicant previously disclosed in Japanese Patent Application No. 4-137,881 (filed on April 30, 1992) a mechanical compliance mechanism at the foot portion of a robot, and a sensor provided at the foot portion is used for detection. We have proposed a compliance control technology that feeds back the generated moment and controls the moment to a predetermined value. In addition to the above, the applicant of the present invention discloses in another Japanese Patent Application No. 4-137,884 (filed on April 30, 1992) ZMP (Zero Momen
t Point), and if the calculated ZMP deviates from the target ZMP, compliance control is performed to drive the foot so as to eliminate the deviation, and the robot always has an inverted pendulum with a certain restoring force. We have proposed a technique for approximating stable walking. Furthermore, Japanese Patent Application No. 4-137,88
No. 5 (filed on April 30, 1992) proposes a technique for further stabilizing the posture by adding a feedback correction according to the posture inclination (inclination angle) of the upper body to the control.

By the way, in the above-mentioned proposed technique, the angle between the floor surface assumed when the desired gait satisfying the dynamic equilibrium condition is created (hereinafter, referred to as "assumed floor surface") and the actual floor surface is formed. When the shapes are the same and there is no other disturbance, the inclination of the actual posture converges to the inclination of the desired posture set when creating the gait. That is, when the difference between the inclination of the actual posture and the inclination of the target posture is called the posture inclination control deviation,
The attitude tilt control deviation converges to zero. However, when the shape of the actual floor surface is different from the shape of the assumed floor surface, that is, when there is a floor surface shape deviation, it becomes a disturbance and a posture tilt control deviation occurs. For example, when there is a tilt deviation between the actual floor surface and the assumed floor surface, if the attitude tilt feedback law is PD control, a steady control deviation of the attitude tilt proportional to the tilt deviation remains.

This will be described with reference to FIG. 18 and FIG. 19. As shown in FIG. 18, the assumed floor surface has an inclination of 0, while the actual floor surface has an inclination of θfloor. When the body deviates from the inclination of the target posture, the joint of the ankle is driven as indicated by an arrow by an amount obtained by multiplying the detected angle θ by the proportional gain K. As a result, the robot recovers the stable posture, but as shown in FIG.
fset remains. That is, from the geometrical relationship, the bending angle of the ankle = the angle of the floor θfloor−θoffset In addition, according to the control law, the bending angle of the ankle = K · θoffset in the steady state. Therefore, θoffset = the angle of the floor θfloor / (K + 1) Becomes If the proportional gain K is set to infinity, the steady control deviation θ
Although the offset approaches 0, since the proportional control gain K has a finite value, the steady control deviation also remains as a finite value.

In order to reduce the steady-state control deviation of such posture inclination to zero, the following can be considered. 1. Attitude tilt feedback rule is PID or I-
Method of integration type such as PD control. 2.6 A method of detecting the external force acting on the leg using an axial force sensor or the like, and making the torque control law of feeding back the detected value to the ankle displacement command to an integral type such as PID or I-PD control. However, in these methods, since the integral element is provided, the loop transfer function is delayed and the system is apt to be unstable. That is, a phase delay occurs and the system easily oscillates.

On the other hand, the steady-state control deviation of the posture inclination can be reduced to zero by using the following method that has been conventionally performed without using the above-proposed technique. 3. This is a method of cutting the ankle displacement control feedback to make the ankle a direct torque control system. 4. A method of making the ankle a current control system. Since these methods do not include displacement control, they are not affected by floor shapes such as slopes, steps, and unevenness. However, when these are used, the control system must be switched to the displacement control system during the swing phase, and there is a disadvantage that shock is likely to occur at the time of switching.

Therefore, the object of the present invention is to eliminate the above-mentioned drawbacks in the previously proposed technique, to estimate the floor surface shape deviation and to correct the posture so as to cancel the floor reaction force deviation caused by the deviation. The present invention provides a walking control device for a legged mobile robot.

Further, by estimating the above-mentioned floor surface shape deviation,
Accordingly, it is an object of the present invention to provide a walking control device for a legged mobile robot configured so as to arbitrarily respond to such a situation as stopping walking of the robot.

Furthermore, the gait control of the legged mobile robot is such that the steady-state control deviation of the attitude inclination, which has been a problem in the previously proposed technique, is made to approach substantially zero without impairing the stability of the attitude inclination control system. The purpose is to provide a device.

[0011]

In order to solve the above-mentioned problems, the present invention is directed to walking of a link type legged mobile robot having an upper body and a plurality of legs, as set forth in claim 1, for example. In the control device, the robot is modeled with a rigid link, and a first means for setting a desired gait for walking on the assumed floor surface assuming the floor surface to be walked, the robot actually Second means for detecting a posture inclination when walking, at least from the detected posture inclination, the posture of the robot is obtained on the assumption that there is no behavior or deformation due to the compliance given to the robot, and the obtained posture and the assumption A third means for obtaining a relative positional relationship with the floor surface, and a figure in which the leg portion comes into contact with the assumed floor surface according to the compliance given to the robot from the obtained relative positional relationship. Fourth estimated according to the characteristics previously set the floor reaction force and / or moment when varying
Means, the fifth means for obtaining the actual floor reaction force and / or moment of the robot, the estimated floor reaction force and / or
Alternatively, sixth means for obtaining a deviation between the moment and the actual floor reaction force and / or the moment, and correcting the assumed floor surface based on the obtained deviation, and correcting the desired gait based on the corrected assumed floor surface The seventh means is provided.

[0012]

[Operation] Focusing on the fact that the difference between the assumed floor surface and the actual floor surface can be quantitatively estimated from the actual floor reaction force, and by using that concept, the shape deviation between the assumed floor surface and the actual floor surface is estimated, Since the floor reaction force deviation caused by the deviation is canceled, it is possible to walk in a more stable posture while utilizing the characteristics of the previously proposed compliance control.

[0013]

Embodiments of the present invention will be described below by taking a bipedal legged mobile robot as an example of the legged mobile robot. FIG. 1 is an explanatory skeleton diagram showing the robot 1 as a whole, and each of the left and right leg links 2 has six joints (each joint is shown by an electric motor for driving it for the sake of convenience). . The six joints are in order from the top, joints 10R and 10L for rotating the legs of the waist (around the z axis) (R on the right side, L on the left side, the same applies below), roll direction of the waist (around the x axis). Joints 12R and 12L, joints 14R and 14L in the same pitch direction (around the y axis), joints 16R and 16L in the pitch direction of the knee, and joint 1 in the pitch direction of the ankle
8R, 18L and joints 20R, 20L in the same roll direction. Foots 22R, 22L are attached to the lower part of the joint, and the upper body (housing 24) is provided at the uppermost position, and the inside thereof The control unit 26 is stored in.

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).
Further, the thigh links 32R, 32 are provided between the hip joint and the knee joint.
L, the lower leg links 34R, 34 between the knee joint and the ankle joint
Connected by L. 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, It is configured so that a desired movement can be given to the robot and the robot can walk arbitrarily in a three-dimensional space. As described above, the above-mentioned joint is composed of an electric motor, and further includes a speed reducer that boosts the output of the electric motor. For details, see yet another application proposed by the applicant (Japanese Patent Application No. 1-324218, JP-A-3-184782
No.) and the like, which are not the gist of the present invention per se, and further description will be omitted.

In the robot 1 shown in FIG. 1, a well-known 6-axis force sensor 36 is provided at the ankle portion, and force components Fx, F in the x, y, z directions transmitted to the robot through the foot.
y, Fz and moment components Mx, M around that direction
By measuring y and Mz, the presence or absence of landing of the foot and the magnitude and direction of the force applied to the supporting leg are detected. Also foot 22R
In the four corners of (L), a capacitance type grounding switch 38 (see FIG.
(Not shown in the figure) is provided to detect whether or not the foot is grounded. Further, an inclination sensor 40 is installed on the upper body 24, and x
The tilt angle and tilt angular velocity with respect to the z axis in the −z plane and the yz plane, that is, with respect to the gravity (vertical) direction are detected. The electric motor of each joint is provided with a rotary encoder that detects the amount of rotation. Further, although omitted in FIG. 1, the inclination sensor 40 is provided at an appropriate position of the robot 1.
An origin switch 42 for compensating the output of No. 1 and a limit switch 44 for fail countermeasure are provided. These outputs are sent to the control unit 26 in the body 24 described above.

FIG. 2 is a block diagram showing the details of the control unit 26, which comprises a microcomputer. The output of the tilt sensor 40 or the like is converted into a digital value by the A / D converter 50, and the output is converted to the bus 52.
Is sent to the RAM 54 via. The output of the encoder arranged adjacent to each electric motor is input into the RAM 54 via the counter 56, and the ground switch 3
Outputs of 8 and the like pass through the waveform shaping circuit 58 and are similarly transferred to the RAM 5
4 is stored. The control unit is provided with first and second arithmetic units 60 and 62 each comprising a CPU. The first arithmetic unit 60 calculates a target joint angle and sends it to the RAM 54, as described later. In addition, the second arithmetic unit 62 reads out the target value and the detected actual value from the RAM 54, calculates the control value necessary for driving each joint, and the each joint via the D / A converter 66 and the servo amplifier. To an electric motor that drives the.

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

FIG. 3 is a block diagram showing the operation,
FIG. 4 is a flow chart showing the operation.

In summary, in this control, the shape (angle) deviation between the expected floor surface and the actual floor surface planned for the desired gait is estimated,
The target gait was modified according to the deviation. That is,
A plane including all or a part of the ground contact portion (usually, the foot 22R (L)) of the posture calculated from the posture inclination and joint displacement of the robot, assuming that the robot does not behave or deform due to compliance. A virtual plane "is virtualized, an angle formed by the virtual plane and the assumed floor surface (hereinafter referred to as" interference angle ", which is shown in FIG. 5) is estimated, and the interference angle is controlled. The floor reaction force is controlled by and the target gait is corrected so that the target floor reaction force is generated.
In other words, while maintaining the relative positional relationship between the planned contact area and the virtual plane, the position
The floor reaction force is controlled by rotationally converting the posture to correct the posture (the rotation angle is the interference angle). From that intention, the interference between the posture (virtual plane) and the assumed floor surface (or the actual floor surface), which is calculated assuming that the robot does not behave or deform due to compliance from the posture inclination and joint displacement described above. A model that represents the relationship between the corner and the floor reaction force when the posture (virtual plane) is deformed so as to contact the assumed floor surface (or actual floor surface) by behavior or deformation due to compliance (hereinafter referred to as "compliance model"). Called). The structure of the model is specifically simplified as follows.

1. The interference angle is used to input the model. 2. The floor reaction force, which is the output of the model, is generally expressed by the force and moment acting on a certain action point. However, if the reference action point is set at or near the desired ZMP of the desired gait, the floor reaction force Even if the force component changes, the posture inclination of the robot hardly changes, and since the main object of the present invention is to control the posture inclination of the robot, the force component of the floor reaction force may be ignored. Therefore, in the compliance model in this embodiment, only the moment component of the floor reaction force around the reference action point is calculated.

In the following, referring to the flow chart of FIG. 4, first, in S10, the estimated inclination of the virtual plane including the planned ground contact portion is obtained from the detected posture inclination value and joint displacement detection value of the robot through kinematics calculation. That is, the actually measured posture of the robot is obtained based on the detected posture inclination value and the detected joint displacement value of the robot, and the planned ground contact portion (foot 22R) in the absolute coordinate system in which the vertical direction coincides with one of the coordinate axes.
A virtual plane including (all or part of (L)) is obtained and the estimated inclination thereof is obtained. In this specification, "tilt" or "tilt" is used to mean "tilt angle".

Subsequently, in S12, the estimated interference angle is obtained by taking the difference between the obtained estimated inclination of the virtual plane and the estimated floor surface inclination described below (initial value is the assumed floor surface inclination).
Next, in S14, an estimated floor reaction force moment around the reference action point (for example, the target ZMP) is obtained from the obtained estimated interference angle based on the compliance model.

This will be described with reference to FIGS. 6 to 8. In FIG. 6, the applicant of the present invention first discloses (Japanese Patent Application No. 4-137,
FIG. 881) is a side view of a robot provided with a mechanical compliance mechanism 100 on the ankle as proposed in No. 881). Assuming that there is no behavior due to compliance, a virtual plane is obtained from the ground contact portion of the supporting leg as shown in the figure, and an interference angle with the actual floor surface is obtained as shown in the figure. Then, when the compliance mechanism 100 operates, as shown in FIG. 7, the compliance mechanism 100 bends (deforms) by an interference angle,
A floor reaction force moment is generated. This means that the interference angle can be estimated by measuring the floor reaction force moment as shown in FIG. The present invention has been made by paying attention to such knowledge, and a virtual plane including a portion that will be grounded assuming that there is no behavior due to compliance and a floor surface (an assumed floor surface and an actual floor surface) It was established from the fact that the shape deviation was expressed by the concept of interference angle and that it could be estimated quantitatively from the floor reaction force moment. Therefore, the characteristics shown in FIG.
Then, the floor reaction force moment is estimated from the estimated interference angle according to the characteristics.

The word "compliance" means ISO /
As defined in TR 8373: 1988 "The flexible behavior of a robot or its associated tools with respect to external forces (The flexible
behavior of a robot or any associated tools in re
sponse to external forces) ", and in that sense," compliance "is based on the mechanism shown in FIG. 6 (FIG. 7) proposed by the applicant in the above-mentioned Japanese Patent Application No. 4-137,881. And the control by the method proposed in Japanese Patent Application No. 4-137,884, etc. However, this specification is not limited to this, and "compliance" is not limited to the illustrated robot links 32, 34R (L). It is used in the sense of including the deformation (deflection) of
The term "compliance" used in this specification has a broader meaning than usual. In the first embodiment, since the estimated inclination of the virtual plane is obtained using the joint displacement detection value, the "compliance" here is given by the deformation of the mechanism or link as shown in FIG. 6 (FIG. 7). Means something.

Next, in S16, the actual floor reaction force moment around the same point of action is obtained from the value detected by the 6-axis force sensor 36. Subsequently, the procedure proceeds to S18, in which the estimated floor surface inclination, which is an estimated value of the inclination deviation between the actual floor surface and the assumed floor surface, is calculated from the difference between the actual floor reaction force moment and the estimated floor reaction force moment according to the illustrated correction rule ( If there is a previous value, correct it) and then add the estimated deviation of floor inclination obtained to the estimated floor inclination to obtain the estimated floor inclination. The correction law may be a low pass filter type, but in order to reduce the steady estimation error,
It is desirable to include pure integration. In the case of the embodiment, the transfer function of the correction law is −K / S (where K is an integration constant).

Next, in S20 and subsequent steps, the posture of the desired gait is corrected so that the desired floor reaction force is generated while canceling out the influence of the detected posture inclination of the robot and the estimated deviation of the floor inclination.

That is, first, in S20, the interference angle in the ideal state is obtained from the desired floor reaction force moment by the inverse compliance model. This inverse compliance model is as shown in FIG. 3, and has the characteristic that the transfer function is opposite to that of the previous compliance model. That is, in this embodiment, since it is premised that the robot is provided with the compliance characteristic proposed in the previous application, in order to generate the floor reaction force expected in the desired gait, the behavior or the link deformation due to the compliance is calculated. It is necessary to add in advance. Therefore, the anti-compliance model as shown is set to obtain the interference angle in the ideal state.

Next, in S22, the interference angle command is determined by adding the difference between the target value and the actual value of the posture inclination and the floor surface inclination estimated deviation obtained in S18 to the obtained interference angle in the ideal state. To do. This is because an extra moment is generated by an amount corresponding to the inclination deviation of the upper body and the inclination deviation of the floor surface (difference between the inclination of the actual floor surface and the assumed floor surface), and is canceled. Next, in S24, the corrected posture in which the interference angle of the desired gait with the assumed floor surface is corrected to the interference angle command is obtained, and in S26, the joint displacement of the actual robot is tracked using the joint displacement of the corrected posture as the joint displacement command. Let

The estimated floor inclination calculated in S18 is shown in FIG.
At the next loop of the flow chart, the estimated interference angle is obtained by using in S12, and S1 is obtained from the obtained value.
At 8, the estimated floor surface inclination is corrected by updating the previous value, and the estimated floor surface inclination is corrected again using the corrected floor surface inclination estimated deviation. In this way, by repeating the correction while assuming that one side is the other side, the floor surface inclination estimation deviation converges to zero. In the first loop of the flow chart of FIG. 4, the initial value of the estimated floor surface inclination is the assumed floor surface inclination as described above, and the initial value of the floor surface inclination estimation deviation is set to zero.

Since this embodiment is configured as described above, the inclination deviation between the actual floor surface and the assumed floor surface is estimated and the desired gait is corrected, so that the floor reaction force deviation caused by the deviation can be canceled. it can. That is, if the gain of the joint displacement control is high in FIG. 3 and the actual joint displacement follows the command almost faithfully, the block diagram of FIG. 3 can be approximated to the block diagram of FIG. 9. As is apparent from FIG. 9, since there is no intervening element between the desired floor reaction force moment and the actual floor reaction force moment, it is not affected by the configuration described in the embodiment. That is, even if the target floor reaction force is manipulated as in the previously proposed technique, there is an element that makes the system unstable, such as oscillation due to a phase delay while the actual floor reaction force is generated from the manipulated variable. Absent. On the other hand, since the correction law includes an integral element, even if there is a tilt deviation between the actual floor surface and the assumed floor surface, the input value to the correction law becomes 0 during settling. Since the input to the correction law is the output of compliance, the output of compliance therefore converges to zero. That is, even if there is a tilt deviation between the actual floor surface and the assumed floor surface, the steady value of the actual floor reaction force moment is not affected.

In the first embodiment, the target gait is corrected after estimating the angle deviation between the assumed floor surface and the actual floor surface. However, the gait can be calculated simply by estimating the angle deviation. You don't have to modify it. This is because, even if the desired gait is not corrected, when it is found that the angular deviation is extremely large, the control such as stopping the walking of the robot can be performed.

FIG. 10 is a block diagram showing a second embodiment of the present invention, and FIG. 11 is a flow chart showing its operation. As shown in the figure, in the second embodiment, the estimated interference angle input to the model is immediately obtained as the difference between the interference angle command and the floor surface inclination estimation deviation (initial value zero) (S100 in the flow chart of FIG. 11). However, it is different from the first embodiment.
Since the interference angle command is used instead of the joint angle displacement detection value to obtain the estimated interference angle in the second embodiment, “compliance” in the second embodiment is due to deformation of the mechanism or link and control. And both are included. The remaining structure and effects are the same as those of the first embodiment.

FIG. 12 is a block diagram showing a third embodiment of the present invention, and FIG. 13 is a flow chart showing its operation. In the third embodiment, as shown in the drawing, the estimated tilt of the virtual plane is obtained from the detected posture tilt value of the robot and the weighted average (value) of the joint displacement detection value and the joint displacement command (value) (FIG. 13). This is different from the first embodiment in S200) of the flow chart. As for the weighting coefficient, if the joint displacement detection value of a certain joint is W (S), that of the joint displacement command (value) is (1-W (S)), but at this time, it is the degree of contribution to the compliance operation. In consideration of the above, joint weights with large contributions are increased in joint displacement detection value, and joints with small contributions are reduced, and joint displacement command values can be used almost as they are for joints with small contributions. It is also possible to reduce the calculation amount of. Besides that, the frequency of the behavior of the joint displacement may be taken into consideration.
Since the joint displacement detection value contains high-frequency noise,
It is even better to give W (S) a low-pass filter characteristic.
The remaining structure and effects are the same as in the first embodiment.
As shown in the drawing, the third embodiment is a mixture of the configurations of the first embodiment and the second embodiment, so that the "compliance" here is partly due to control and deformation due to mechanism or link. Including and

FIG. 14 is a block diagram showing a fourth embodiment of the present invention, and FIG. 15 is a flow chart showing its operation. As shown in the figure, the feature of the fourth embodiment is that, contrary to the previous embodiment, the floor surface inclination estimated deviation is obtained by obtaining the interference angle from the floor reaction force moment to obtain the estimated floor surface inclination. . That is, the anti-compliance model shown in FIG. 3 or the like is connected to the next stage of the 6-axis force sensor and its processing calculator, and the posture of the robot is obtained from the detected floor reaction force moment to determine the interference angle (first It will be estimated. On the other hand, the estimated inclination of the floor surface is subtracted from the estimated inclination of the virtual plane including the planned contact area to obtain the estimated interference angles (second) as before, and the deviation of the estimated interference angles is obtained to estimate the floor inclination. I asked for. More specifically, in order to compare the second estimated interference angle with the first estimated interference angle in the same dimension, the inverse compliance model is connected to the next stage of the compliance model in the configuration of FIG. However, at that time, the product of the transfer functions of both models becomes 1, and as a result, the two cancel each other.

Due to the difference in the above configuration, S304 to S308 in the flow chart of FIG. 15 are different from the flow chart of FIG. 3 of the first embodiment.
The remaining structure is the same as that of the first embodiment. Further, although an example of obtaining the estimated floor surface inclination by using the interference angle instead of the floor reaction force moment is shown only when the first embodiment is modified, the present invention is not limited to this and the disclosure is omitted. It goes without saying that it is possible by modifying the second embodiment or the third embodiment.

FIG. 16 is a block diagram showing a fifth embodiment of the present invention. In this example, a feedback control loop for the floor reaction force is added to the outside of the configuration of the first example. In the case of the fifth embodiment, this configuration can further improve the control accuracy of the floor reaction force control.

FIG. 17 is a block diagram showing a sixth embodiment of the present invention. In this example, the configuration of the first embodiment and the like is applied to a minor loop of posture inclination control, and a desired floor reaction force moment is operated according to the posture inclination. In the case of the sixth embodiment, it is possible to realize the posture inclination control that is not easily influenced by the floor surface shape deviation, and it is possible to eliminate the steady deviation. That is, when the inclination of the actual floor surface is different from the assumed inclination of the floor surface, a floor reaction force deviation occurs, and even if it is attempted to cancel it by performing feedback control of the body and posture inclination to the target value, The steady-state deviation remains as described with reference to FIGS. 18 and 19. However, as a result of the configuration shown in FIG. 17, even if there is a tilt deviation between the actual floor surface and the assumed floor surface, it can be estimated and canceled. At this time, as described above with reference to FIG. 9, since the correction rule includes the integral element, the steady deviation does not appear, and the integral element is used as the target floor reaction force moment (input) in the configuration of FIG. Without interposing between the actual floor reaction force moment (output), that is, there is no intervening thing including the integral element, so if the target floor reaction force is corrected, the actual floor reaction force will be corrected. The reaction force also reacts immediately, no phase delay occurs, and the system does not oscillate.

In the structures of the first to sixth embodiments described above, in the one-leg supporting period, when the joint displacement command is obtained from the interference angle command and the desired gait, the joint displacement command of the supporting leg ankle You may only fix it. In that case, the inverse kinematics calculation is not required, and the calculation amount is greatly reduced. Further, even in the two-leg supporting period, the floor reaction force obtained by combining all the floor reaction forces of each foot is controlled as in the embodiment, but when it is desired to control the floor reaction force of each foot independently, The interference angle of each foot may be manipulated with respect to the foot. However,
Controllability is not very good because control interference between legs occurs.

Further, in the above configuration, the floor shape is estimated by comparing the estimated value and the detected value with respect to the floor reaction force moment. Generally, the floor reaction force is represented by a force, a moment, and an action point, or a ZMP, a force acting on the ZMP, and a moment in the floor normal direction. In any of the expressions, not all the components are related to the posture control, so only the necessary elements need be obtained. The model can output only what is needed. When the floor reaction force is expressed using the desired ZMP of the desired gait as the reference point of action, the force component has almost no relation to the behavior of the posture inclination, and thus may be omitted. The output of the model may be the amount of deviation between the ZMP position of the floor reaction force of the model and the target ZMP. The reference point of action is a part of the robot, such as the ankle (ankle 18,
It may be at the intersection of 20R (L). That is, if the ankle moment is used instead of the floor reaction force moment in the embodiment, control of the ankle moment is realized.

Further, in the above construction, the difference between the actual floor surface and the assumed floor surface is an angle, but it is not limited to this, and it may be a step, for example. However, in the above-mentioned configuration, even if the difference in level is actually the difference, the estimated amount is estimated as the difference in average inclination. If it is known in advance that the characteristics of the actual floor surface are such that there is no change in inclination but there is an indeterminate step, or that the inclination angle changes smoothly without a step, the estimated amount should be changed accordingly. Or it may be inclined. When the inclination deviation is estimated as in the above-described configuration, the gait interference angle is corrected, but when the step deviation is estimated, the ground contact heights of both legs may be corrected. Furthermore, “inclination” and “inclination” mean an inclination angle, but an inclination angular velocity or a value obtained by linearly combining both may be used instead of the inclination angle.

Further, in the above construction, when a landing impact occurs, the actual floor reaction force may change drastically and may not be accurately estimated. Therefore, the correction gain K is set to a small value or set to zero. Better Even when the vertical floor reaction force is small or is 0 during the swing period or when the robot bounces, it is better to lower the correction gain or set it to 0. Further, the floor surface inclination estimation deviation may be set to 0 or may be gradually returned to 0.

Further, in the one-leg supporting period, the limit at which the floor reaction force moment can be generated is determined by the size of the foot contact surface and the vertical floor reaction force, and the nonlinear model as shown in the compliance model of FIG. It has characteristics. The inverse compliance characteristic is naturally also non-linear, and when the target floor reaction force increases, the output interference angle increases rapidly. Since it is not desirable that the interference angle of the real robot becomes too large,
It is better to provide an interference angle limiter in the inverse compliance model so that the interference angle does not increase even if the target floor reaction force becomes too large. Alternatively, the characteristics of the inverse compliance model may be linearized to prevent the interference angle from rapidly increasing.

Further, since the compliance characteristic changes depending on the walking cycle such as the one-leg supporting period or the two-leg supporting period, if the compliance model in the above configuration is also changed depending on the walking period, the estimation accuracy of the floor shape deviation becomes high. .

Further, the compliance model shown in the above-mentioned configuration gives only the spring characteristic and does not consider the damping characteristic. However, for the robot having the damper characteristic, the model considering the damping characteristic is set. May be.

Further, in the above configuration, the floor inclination is estimated. Therefore, if it is known that the change in the inclination is gentle, the floor inclination in the next step is predicted and the next step is taken. The desired gait itself may be changed in real time to a gait suitable for the estimated inclined floor surface.

Further, in the estimation of the floor surface inclination deviation, the estimation deviation should not change even if the floor reaction force changes after the estimation deviation converges by the correction rule. If they are different, if the floor reaction force changes, the correction of the estimated deviation malfunctions and the estimated deviation also changes. Since the correction law is composed of integration and low-pass filter elements, this malfunction causes a delay in floor reaction force control, and in the worst case, oscillation may occur. In order to prevent this, adaptive control that matches the compliance model with the identification value may be performed while identifying the compliance of the actual robot. With adaptive control,
Observe the fluctuation of the estimated floor reaction force output from the compliance model when the actual floor reaction force fluctuates, and the fluctuation amount is
It is identified so as to match the variation of the real robot.

Further, although the bipedal legged mobile robot has been described above as an example, the present invention is not limited to this, and the present invention is also applicable to a legged mobile robot having three or more legs. However, it is applicable to other types of mobile robots such as wheel type and crawler type.

[0048]

According to the first aspect of the present invention, in a walking control device for a link type legged mobile robot having an upper body and a plurality of legs, the robot is modeled with a rigid link to walk. First means for setting a desired gait for walking on the assumed floor surface assuming a planned floor surface, second means for detecting a posture inclination when the robot actually walks, at least Third means for obtaining the posture of the robot from the detected posture inclination on the assumption that there is no behavior or deformation due to the compliance given to the robot, and for obtaining a relative positional relationship between the obtained posture and the assumed floor surface. ,
Fourth means for estimating a floor reaction force and / or a moment when the posture is changed so that the leg portion comes into contact with the assumed floor surface by the compliance given to the robot, from the obtained relative positional relationship, Fifth means for obtaining the actual floor reaction force and / or moment of the robot, obtaining a deviation between the estimated floor reaction force and / or moment and the actual floor reaction force and / or moment, and based on the obtained deviation Since the sixth means for correcting the assumed floor surface and the seventh means for correcting the desired gait on the basis of the corrected assumed floor surface are provided, the floor surface and the actual floor assumed by the desired gait Even if there is a difference in shape such as the angle with the floor surface, the target gait itself is corrected so as to cancel the floor reaction force deviation caused by it, so it is possible to always walk in a stable posture. Kill.

According to a second aspect of the present invention, in a walking control device for a link type legged mobile robot having an upper body and a plurality of legs, the robot is modeled by a rigid link,
First means for setting a desired gait for walking on the assumed floor surface assuming a floor surface to be walked, and second means for detecting a posture inclination when the robot actually walks A. At least from the detected posture inclination, the posture of the robot is obtained on the assumption that there is no behavior or deformation due to compliance given to the robot, and a relative positional relationship between the obtained posture and the assumed floor surface is obtained. The characteristic that presets the floor reaction force and / or the moment when the posture is changed so that the leg is in contact with the assumed floor surface according to the compliance given to the robot from the obtained relative positional relationship. A fourth means of estimating according to
Fifth means for obtaining an actual floor reaction force and / or moment of the robot, and a deviation between the estimated floor reaction force and / or moment and the actual floor reaction force and / or moment is obtained, and based on the obtained deviation Since it is configured to include the sixth means for correcting the assumed floor surface, the walking of the robot is stopped according to the difference in shape between the assumed floor surface and the actual floor surface, although the structure is simpler. This makes it possible to prevent the posture from becoming more unstable.

According to a third aspect of the present invention, in a walking control device for a link type legged mobile robot having an upper body and a plurality of legs, the robot is modeled by a rigid link,
First means for setting a desired gait for walking on the assumed floor surface assuming a floor surface to be walked, and second means for detecting a posture inclination when the robot actually walks A third means for obtaining a posture of the robot from at least the detected posture inclination and a first relative positional relationship between the obtained posture and the assumed floor surface, an actual floor reaction force of the robot, and / or The fourth means of determining the moment,
Fifth means for obtaining a second relative positional relationship between the posture of the robot and the assumed floor surface according to preset characteristics from the obtained actual floor reaction force and / or moment, the first and second means. Sixth means for obtaining a deviation of the relative positional relationship and correcting the assumed floor surface based on the obtained deviation, and seventh means for correcting the desired gait based on the corrected assumed floor surface are provided. With this configuration, the same effect as described in claim 1 can be obtained.

According to a fourth aspect of the present invention, in a walking control device for a link type legged mobile robot having an upper body and a plurality of legs, the robot is modeled by a rigid link,
First means for setting a desired gait for walking on the assumed floor surface assuming a floor surface to be walked, and second means for detecting a posture inclination when the robot actually walks A third means for obtaining a posture of the robot from at least the detected posture inclination and a first relative positional relationship between the obtained posture and the assumed floor surface, an actual floor reaction force of the robot, and / or The fourth means of determining the moment,
Fifth means for obtaining a second relative positional relationship between the posture of the robot and the assumed floor surface according to preset characteristics from the obtained actual floor reaction force and / or moment, and the first and second means. The relative positional deviation of
Since the sixth means for correcting the assumed floor surface based on the obtained deviation is provided, the same effect as described in claim 2 can be obtained.

In the fifth aspect, the third means is configured to obtain the posture of the robot from the detected posture inclination and the joint displacement detection value of the link of the robot. The difference between the floor surface and the actual floor surface can be accurately estimated, and the desired gait can be appropriately corrected.

In the sixth aspect, the third means is configured to obtain the posture of the robot from the detected posture inclination and the joint displacement command value of the link of the robot. Although it has a simple structure, the same effect can be obtained.

In the seventh aspect, the third means determines the posture of the robot from the detected posture inclination, a weighted average value of the joint displacement detection value of the robot link and the joint displacement command value. Therefore, it is possible to use, for example, the command value of the joint having a low contribution to the compliance operation as it is, and the same effect can be obtained while reducing the calculation amount.

In the eighth aspect, the sixth means is configured to correct the virtual floor surface by using a correction rule including an integral element, so that the steady deviation can be brought close to zero. .

In the ninth aspect, the seventh means is constituted so as to include the feedback control means for correcting the desired gait so that the obtained actual posture inclination becomes the desired value. When correcting the assumed floor surface using a correction rule including elements, the steady deviation can be brought close to zero, and if the gain of the joint displacement control system is high, the target floor reaction force and the actual floor can be corrected. Since there is no intervening force with the reaction force, there is no phase delay and no system instability.

[Brief description of drawings]

FIG. 1 is an explanatory diagram generally showing a walking control device for a legged mobile robot according to the present invention.

2 is a block diagram showing details of a control unit in FIG. 1. FIG.

FIG. 3 is a block diagram showing a first embodiment of the present invention.

FIG. 4 is a flow chart showing the operation of the first embodiment.

5 is an explanatory diagram showing interference angles shown in FIGS. 3 and 4. FIG.

FIG. 6 is an explanatory diagram showing the operation of the mechanical compliance mechanism previously proposed by the applicant in association with the interference angle.

FIG. 7 is an explanatory diagram showing a state in which the mechanism shown in FIG. 6 is bent by an interference angle.

FIG. 8 is an explanatory diagram showing the relationship between the floor reaction force moment and the interference angle, which is the basis of the present invention, obtained from FIGS. 6 and 7.

FIG. 9 is a block diagram showing a state in which the block diagram of FIG. 3 is approximated.

FIG. 10 is a block diagram showing a second embodiment of the present invention.

FIG. 11 is a flow chart showing the operation of the second embodiment.

FIG. 12 is a block diagram showing a third embodiment of the present invention.

FIG. 13 is a flow chart showing the operation of the third embodiment.

FIG. 14 is a block diagram showing a fourth embodiment of the present invention.

FIG. 15 is a flow chart showing the operation of the fourth embodiment of the present invention.

FIG. 16 is a block diagram showing a fifth embodiment of the present invention.

FIG. 17 is a block diagram showing a sixth embodiment of the present invention.

FIG. 18 is an explanatory diagram showing a state in which the robot has an unstable posture on an inclined floor surface.

FIG. 19 is an explanatory diagram showing a steady-state deviation when the posture is recovered in the state of FIG.

[Explanation of Codes] 1-legged mobile robot (bipedal walking robot) 2 leg links 10R, 10L joints for rotating legs 12R, 12L joints in the roll direction of the waist 14R, 14L joints in the pitch direction of the waist 16R, 16L Knee pitch direction joint 18R, 18L Ankle pitch direction joint 20R, 20L Ankle roll direction joint 22R, 22L Foot 24 Body 24 Control unit 36 6-axis force sensor 100 Mechanical compliance mechanism

Claims (9)

[Claims] 1. A walking control device for a link-type legged mobile robot having an upper body and a plurality of legs, comprising: a. First means for modeling the robot with a rigid link and setting a desired gait for walking on the assumed floor surface assuming a floor surface to be walked, b. Second means for detecting a posture inclination when the robot actually walks; c. At least from the detected posture inclination, the posture of the robot is obtained on the assumption that there is no behavior or deformation due to the compliance given to the robot, and a relative positional relationship between the obtained posture and the assumed floor surface is obtained. Means, d. From the obtained relative positional relationship, the floor reaction force and / or the moment when the posture is changed by the compliance given to the robot so that the legs come into contact with the assumed floor surface are estimated according to preset characteristics. Fourth means, e. Fifth means for determining the actual floor reaction force and / or moment of the robot, f. Sixth means for obtaining a deviation between the estimated floor reaction force and / or moment and the actual floor reaction force and / or moment, and correcting the assumed floor surface based on the obtained deviation, and g. A walking control device for a legged mobile robot, comprising: a seventh means for correcting the desired gait based on the corrected assumed floor surface. 2. A walking control device for a link type legged mobile robot having a body and a plurality of legs, comprising: a. First means for modeling the robot with a rigid link and setting a desired gait for walking on the assumed floor surface assuming a floor surface to be walked, b. Second means for detecting a posture inclination when the robot actually walks; c. At least from the detected posture inclination, the posture of the robot is obtained on the assumption that there is no behavior or deformation due to the compliance given to the robot, and a relative positional relationship between the obtained posture and the assumed floor surface is obtained. Means, d. From the obtained relative positional relationship, the floor reaction force and / or the moment when the posture is changed by the compliance given to the robot so that the legs come into contact with the assumed floor surface are estimated according to preset characteristics. Fourth means, e. Fifth means for determining the actual floor reaction force and / or moment of the robot, and f. Sixth means for obtaining a deviation between the estimated floor reaction force and / or moment and the actual floor reaction force and / or moment, and correcting the assumed floor surface based on the obtained deviation, A walking control device for a legged mobile robot. 3. A walking control device for a link-type legged mobile robot having an upper body and a plurality of legs, comprising: a. First means for modeling the robot with a rigid link and setting a desired gait for walking on the assumed floor surface assuming a floor surface to be walked, b. Second means for detecting a posture inclination when the robot actually walks; c. Third means for obtaining a posture of the robot from at least the detected posture inclination and obtaining a first relative positional relationship between the obtained posture and the assumed floor surface, d. Fourth means for determining the actual floor reaction force and / or moment of the robot, e. Fifth means for obtaining a second relative positional relationship between the posture of the robot and the assumed floor surface from the obtained actual floor reaction force and / or moment according to preset characteristics, f. The deviation between the first and second relative positional relationships is calculated,
Sixth means for correcting the assumed floor surface based on the obtained deviation, and g. A walking control device for a legged mobile robot, comprising: a seventh means for correcting the desired gait based on the corrected relative floor surface. 4. A walking control device for a link-type legged mobile robot having an upper body and a plurality of legs, comprising: a. First means for modeling the robot with a rigid link and setting a desired gait for walking on the assumed floor surface assuming a floor surface to be walked, b. Second means for detecting a posture inclination when the robot actually walks; c. Third means for obtaining a posture of the robot from at least the detected posture inclination and obtaining a first relative positional relationship between the obtained posture and the assumed floor surface, d. Fourth means for determining the actual floor reaction force and / or moment of the robot, e. Fifth means for obtaining a second relative positional relationship between the posture of the robot and the assumed floor surface according to preset characteristics from the obtained actual floor reaction force and / or moment, and f. The deviation between the first and second relative positional relationships is calculated,
A walking control device for a legged mobile robot, comprising: a sixth means for correcting the assumed floor surface based on the obtained deviation. 5. The method according to claim 1, wherein the third means obtains the posture from the detected posture inclination and a joint displacement detection value of the link of the robot. A walking control device for the legged mobile robot described. 6. The method according to claim 1, wherein the third means obtains the posture from the detected posture inclination and a joint displacement command value of the link of the robot. A walking control device for the legged mobile robot described. 7. The third means obtains the posture from the detected posture inclination, a joint displacement detection value of a link of the robot, and a weighted average value of joint displacement command values. A walking control device for a legged mobile robot according to any one of items 1 to 4. 8. The legged mobile robot according to claim 1, wherein the sixth means corrects the assumed floor surface using a correction rule including an integral element. Walking control device. 9. The method according to claim 1, wherein the seventh means includes feedback control means for correcting the desired gait so that the calculated actual posture inclination becomes a desired value.
Item 5. A walking control device for a legged mobile robot according to any one of items 5 to 8.