JP3024028B2 - 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 specifically, to estimate a tilt angle of an actual floor surface and to determine a deviation from a floor surface tilt angle assumed in a target gait. And correcting the posture so as to cancel the floor reaction force deviation generated by the deviation.

[0002]

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

[0003]

By the way, a legged mobile robot, particularly a legged mobile robot that walks on two legs, naturally tends to have an unstable posture. In view of this, the present applicant previously disclosed in Japanese Patent Application No. 4-137,881 (filed on April 30, 1992) a mechanical compliance mechanism provided at the foot of a robot, and detection was performed by a sensor provided at the foot. Has proposed a compliance control technique in which the moment is fed back to control the moment to a predetermined value. Separately, the present applicant filed another Japanese Patent Application No. 4-137,884 (filed on April 30, 1992) with a ZMP (Zero Momen).
t Point), and if the calculated ZMP deviates from the target ZMP, compliance control for driving the foot is performed so as to eliminate the deviation, and the robot always has an inverted pendulum with a certain restoring force. A technique for walking stably by approximating with. 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 body to the control.

In the above-mentioned proposed technology, the angle between the floor surface assumed when creating a desired gait satisfying the dynamic equilibrium condition (hereinafter referred to as “assumed floor surface”) and the actual floor surface is described. If the shapes match, and there is no other disturbance, the inclination of the actual posture converges to the inclination of the target posture set when the gait was created. That is, when the difference between the inclination of the actual posture and the inclination of the target posture is referred to as a posture inclination control deviation,
The attitude tilt control deviation converges to zero. However, if the shape of the actual floor surface is different from the assumed floor shape, that is, if there is a floor 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 posture inclination feedback rule is PD control, a steady control deviation of the posture inclination proportional to the inclination deviation remains.

This will be described with reference to FIGS. 18 and 19. As shown in FIG. 18, while the inclination of the assumed floor is 0, the inclination of the actual floor is θfloor, and When the body deviates from the inclination of the target posture, the joint of the ankle is driven as shown 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 posture stability, but as shown in FIG. 19, the steady control deviation θof
fset remains. That is, from the geometrical relationship, the bending angle of the ankle = the angle of the floor θfloor−θoffset Also, according to the control law, the bending angle of the ankle = K · θoffset in a steady state, so that θoffset = the floor angle θfloor / (K + 1) Becomes If the proportional gain K is made infinite, the steady-state control deviation θ
Although the offset approaches 0, since the proportional control gain K is a finite value, the steady control deviation also remains as a finite value.

In order to make the steady control deviation of such a posture inclination zero, the following is conceivable. 1. PID or I-
Integral method such as PD control. 2. A method in which an external force acting on a leg is detected using a 6-axis force sensor or the like, and a torque control law that feeds back a detected value to an ankle displacement command is an integral type such as PID or I-PD control. However, in these methods, the provision of the integral element tends to cause a delay in the loop transfer function and make the system unstable. That is, a phase lag occurs, and the system easily oscillates.

On the other hand, the steady control deviation of the posture inclination can be made zero by using the following method conventionally used without using the above-mentioned proposed technique. 3. A method that cuts the ankle displacement control feedback and turns the ankle into a direct torque control system. 4. A method to make 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 irregularities. 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 an impact is likely to occur at the time of switching.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned drawbacks in the previously proposed technique, to estimate a floor shape deviation, and to correct the posture so as to cancel a floor reaction force deviation caused by the deviation. To provide a walking control device for a legged mobile robot.

Further, the aforementioned floor shape deviation is estimated,
It is an object of the present invention to provide a walking control device for a legged mobile robot configured to be able to respond arbitrarily, for example, to stop walking of the robot in response thereto.

Further, the walking control of a legged mobile robot can reduce the steady-state control deviation of the posture inclination, which has been a problem with the previously proposed technology, to substantially zero without impairing the stability of the posture inclination control system. It is intended to provide a device.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides, for example, a walking method of a link-type legged mobile robot having an upper body and a plurality of legs. In the control device, the robot is modeled by a rigid link, and a first means for setting a target gait for walking on the assumed floor, assuming a floor on which the robot is to be walked, A second means for detecting the posture inclination when walking, at least from the detected posture inclination, obtaining the posture of the robot assuming that there is no behavior or deformation due to compliance given to the robot, and obtaining the obtained posture and the assumption Third means for obtaining a relative positional relationship with the floor surface, based on the obtained relative positional relationship, the legs are brought into contact with the assumed floor surface by compliance given to the robot. Fourth estimated according to the characteristics previously set the floor reaction force and / or moment when varying
Means for determining the actual floor reaction force and / or moment of the robot, estimated floor reaction force and / or moment
Or, a sixth means for obtaining a deviation between the moment and the actual floor reaction force and / or moment, and correcting the assumed floor based on the obtained deviation, and correcting the desired gait based on the corrected assumed floor It is configured to include a seventh means for performing the above.

[0012]

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

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below, taking a bipedal legged mobile robot as an example of a legged mobile robot. FIG. 1 is an explanatory skeleton diagram showing the robot 1 as a whole. The left and right leg links 2 are provided with six joints (for 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 rotation of the waist leg (around the z-axis) (R on the right and L on the left; the same applies hereinafter), and the 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 knee pitch direction, and joint 1 in the ankle pitch direction.
8R, 18L, and joints 20R, 20L in the same roll direction. Foot 22R, 22L is attached to the lower part, and the upper body (housing 24) is provided at the uppermost position. Stores a control unit 26.

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 provided with a speed reducer or the like for boosting its output. The details thereof are described in another application (Japanese Patent Application No. 1-324218, JP-A-3-184772
), And the description itself is not the gist of the present invention.

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 via 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 inclination angle and the inclination 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 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 the details of the control unit 26, which comprises 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 through a waveform shaping circuit 58.
4 is stored. In the control unit, first and second arithmetic units 60 and 62 each including a CPU are provided. The first arithmetic unit 60 calculates a target joint angle and sends it to the RAM 54 as described later. Further, the second arithmetic unit 62 reads out the target value and the detected actual value from the RAM 54, calculates a control value required for driving each joint, and outputs the control value to each joint via a D / A converter 66 and a servo amplifier. To the electric motor that drives the motor.

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

FIG. 3 is a block diagram showing the operation.
FIG. 4 is a flowchart showing the operation.

In general, in this control, the shape (angle) deviation between the assumed floor surface and the actual floor surface planned in the target gait is estimated,
The target gait is modified according to the deviation. That is,
A plane (hereinafter, referred to as “the foot 22R (L)”) that includes all or a part of the ground contacting part (usually the foot 22R (L)) of the posture determined assuming that the robot does not behave or deform due to compliance from the posture inclination and joint displacement of the robot. Estimating the angle between the virtual plane and the assumed floor surface (hereinafter referred to as “interference angle”, which is shown in FIG. 5), and controlling the interference angle. Controls the floor reaction force and corrects the desired gait so that the desired floor reaction force is generated.
In other words, while maintaining the relative positional relationship between the planned ground contact portion and the virtual plane, the position at which the virtual plane is virtually tilted
The floor reaction force is controlled by correcting the posture by converting the rotation to the posture (the rotation angle is the interference angle). From the intention, the interference between the posture (virtual plane) and the assumed floor (or actual floor), which is obtained from the posture inclination and joint displacement of the robot described above, assuming that the robot has no behavior or deformation due to compliance. A model that represents the relationship between the angle and the floor reaction force when the posture (virtual plane) is deformed so as to be in contact with the assumed floor (or actual floor) by the behavior or deformation due to compliance (hereinafter, the “compliance model”) ). Specifically, the configuration of the model is simplified as follows.

1. The interference angle is used for inputting the model. 2. The floor reaction force, which is the output of the model, is generally represented by the force and moment acting on a certain point of action. However, if the reference point of action is set at or near the target 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 can be ignored. Therefore, the compliance model in the present embodiment calculates only the moment component of the floor reaction force around the reference point of action.

Referring to the flow chart of FIG. 4, first, in step S10, an estimated inclination of a virtual plane including a portion to be grounded is obtained from the detected posture inclination and joint displacement of the robot through kinematics calculation. That is, the actual posture of the robot is determined based on the detected value of the posture and inclination of the robot and the detected value of the joint displacement, and the ground contact portion (foot 22R) in the absolute coordinate system whose vertical direction coincides with one of the coordinate axes is obtained.
A virtual plane including all or a part of (L) is obtained, and its estimated inclination is obtained. In this specification, “slope” or “slope” is used to mean “slope angle”.

Then, the process proceeds to S12, in which a difference between the obtained estimated inclination of the virtual plane and an estimated floor inclination described later (the initial value is an assumed floor inclination) is determined to obtain an estimated interference angle.
Subsequently, in S14, an estimated floor reaction force moment around a reference action point (for example, a 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. FIG. 6 shows that the applicant of the present invention has previously described (Japanese Patent Application No. 4-137,
No. 881) is a side view of a robot provided with a mechanical compliance mechanism 100 on an ankle. Assuming that there is no behavior due to compliance, a virtual plane is obtained as shown in the figure from the support leg contact portion, and an interference angle with the actual floor surface is obtained as shown. Then, when the compliance mechanism 100 operates, the compliance mechanism 100 bends (deforms) by the interference angle as shown in FIG.
A floor reaction force moment occurs. 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 it is assumed that a virtual plane including a portion that will be in contact with a ground when 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 idea that the shape deviation was expressed by the concept of interference angle and that it could be quantitatively estimated 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 characteristic.

The word "compliance" is ISO /
The flexible behavior of a robot or its associated tools against external forces as defined in TR 8373: 1988 (The flexible
behavior of a robot or any associated tools in re
sponse to externalforces). In this sense, “compliance” is based on the mechanism shown in FIG. 6 (FIG. 7) which was previously proposed by the present applicant in Japanese Patent Application No. 4-137,881. And those based on control proposed in Japanese Patent Application No. 4-137,884, etc. However, this specification is not limited to this, and "compliance" refers to the illustrated robot links 32, 34R (L), etc. It is used in the sense including the deformation (bending).
The term “compliance” in this specification is used in a broader sense than usual. In the first embodiment, since the estimated inclination of the virtual plane is obtained by using the detected value of the joint displacement, the “compliance” here is given by the deformation of the mechanism or the link as shown in FIG. 6 (FIG. 7). Means things.

Subsequently, the program proceeds to S16, where the actual floor reaction force moment around the same point of action is determined from the value detected by the six-axis force sensor 36. Then, the process proceeds to S18, where a floor inclination estimation deviation, which is an estimated value of the inclination deviation between the actual floor surface and the assumed floor surface, is obtained from the difference between the actual floor reaction force moment and the estimated floor reaction force moment by the illustrated correction rule ( The value is corrected if there is a previous value), and the estimated floor surface inclination deviation obtained is added to the assumed floor surface inclination to obtain an estimated floor surface inclination. Note that the correction rule may be a low-pass filter type, but in order to reduce the steady-state estimation error,
It is desirable to include pure integration. In the case of the embodiment, the transfer function of the correction rule was -K / S (where K is an integration constant).

Then, the process proceeds to S20 and the following steps to correct the posture of the desired gait such that the desired floor reaction force is generated while canceling the effects of the detected posture inclination of the robot and the estimated deviation of the floor inclination.

That is, first, the process proceeds to S20, where an interference angle in an ideal state is obtained from the desired floor reaction force moment by an inverse compliance model. This inverse compliance model is as shown in FIG. 3, and has a characteristic that the transfer function is opposite to that of the previous compliance model. That is, in this embodiment, since it is assumed that the robot is provided with the compliance characteristic proposed in the earlier application, in order to generate the floor reaction force expected in the target gait, the behavior due to compliance or the amount of link deformation is determined. It is necessary to add in advance. Therefore, an interference angle in an ideal state is obtained by setting an inverse compliance model as shown.

The program then proceeds to S22, in which the interference angle command is determined by adding the difference between the target value and the actual value of the posture inclination to the estimated interference angle in the ideal state and the estimated floor inclination calculated in S18. I do. This is because an extra moment is generated by the inclination deviation of the upper body and the deviation of the floor surface inclination (difference between the actual floor surface and the assumed floor surface), and is canceled. Then, the process proceeds to S24 to obtain a corrected posture in which the interference angle of the target gait with the assumed floor surface is corrected to the interference angle command, and proceeds to S26 to follow the joint displacement of the real robot using the joint displacement of the corrected posture as the joint displacement command. Let it.

The estimated floor inclination obtained in S18 is shown in FIG.
In 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 inclination is corrected by updating the previous value, and the estimated floor inclination is corrected again using the corrected estimated floor inclination. In this way, by repeating the correction while one is based on the other, the estimated deviation of the floor inclination converges to zero. In the first loop of the flow chart of FIG. 4, the initial value of the estimated floor inclination is set to the assumed floor inclination as described above, and the initial value of the estimated deviation of the floor inclination is set to zero.

Since this embodiment is constructed as described above, it is possible to estimate the inclination deviation between the actual floor surface and the assumed floor surface and correct the desired gait, so that the floor reaction force deviation caused by the deviation can be canceled. it can. That is, if the joint displacement control gain is high in FIG. 3 and the actual joint displacement follows the command almost exactly, the block diagram in FIG. 3 can be approximated to the block diagram in FIG. As is clear from FIG. 9, since there is no intervening element between the desired floor reaction force moment and the actual floor reaction force moment, there is no influence from the configuration described in the embodiment. That is, even if the target floor reaction force is operated as in the technology proposed earlier, there are factors that make the system unstable, such as oscillating due to a phase delay while the actual floor reaction force is generated from the operation amount. Absent. On the other hand, since the correction rule includes an integral element, the input value to the correction rule becomes zero at the time of settling even if there is a tilt deviation between the actual floor surface and the assumed floor surface. Since the input to the correction rule is the output of the compliance, the output of the compliance converges to zero. That is, even if there is an inclination 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, an example is shown in which the target gait is corrected after estimating the angle deviation between the assumed floor surface and the actual floor surface. However, the gait is simply estimated by estimating the angle deviation. You do not need to modify it. This is because, even if the target gait is not corrected, when it is determined that the angle deviation is extremely large, 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 flowchart showing the operation thereof. 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 estimated deviation of the floor inclination (the initial value is zero) (S100 in the flow chart of FIG. 11). However, this is different from the first embodiment.
In the second embodiment, the interference angle command is used instead of the joint angle displacement detection value to obtain the estimated interference angle. Therefore, the “compliance” in the second embodiment is based on the deformation of the mechanism or the link and the control. And both. The remaining configuration and effects are not different from 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 the operation thereof. In the third embodiment, as shown, the estimated inclination of the virtual plane is determined from the detected posture inclination of the robot, the weighted average of the joint displacement detection value and the joint displacement command (value) (FIG. 13). The flow chart differs from the first embodiment in S200). Assuming that the weight of the joint displacement detection value of a certain joint is W (S), the weight of the joint displacement command (value) is (1-W (S)). In consideration of the above, the weight of the joint displacement detection value is increased for joints with a large contribution and the joints with small contribution can be used almost as it is for joints with a small contribution, Can be reduced. In addition, the frequency of the behavior of the joint displacement may be considered.
Since the joint displacement detection value contains high-frequency noise,
It is better to give a low-pass filter characteristic to W (S).
The remaining configuration and effects are not different from those of the first embodiment.
In the third embodiment, as shown in the figure, the configurations of the first and second embodiments are mixed, so that the "compliance" here is a part of the control and the deformation of the mechanism or the link. And

FIG. 14 is a block diagram showing a fourth embodiment of the present invention, and FIG. 15 is a flowchart showing the operation thereof. The feature of the fourth embodiment is that, as shown in the drawing, contrary to the previous embodiment, an interference angle is obtained from a floor reaction force moment to obtain an estimated floor inclination deviation to obtain an estimated floor inclination. . That is, the reverse compliance model shown in FIG. 3 or the like is connected to the next stage of the 6-axis force sensor and its processing operation unit, and the posture of the robot is obtained from the detected floor reaction force moment to obtain the interference angle (first and second). To be estimated). On the other hand, the estimated floor angle is subtracted from the estimated slope of the virtual plane including the planned ground contact area to obtain the estimated interference angle (second) as before, and the deviation of the estimated interference angle is determined to obtain the floor surface tilt estimation deviation. I asked for. More specifically, in order to compare the second estimated interference angle with the first estimated interference angle in the same dimension, in the configuration of FIG. 3, an inverse compliance model is connected to the next stage of the compliance model. However, at this time, the product of the transfer functions of both models is 1, and as a result, both are canceled.

Due to the difference in the above configuration, steps S304 to S308 are different in the flow chart of FIG. 15 from the flow chart of FIG. 3 of the first embodiment.
The remaining configuration is not different from the first embodiment. Further, an example in which the estimated floor inclination is obtained using the interference angle instead of the floor reaction force moment is shown only when the first embodiment is modified. However, the present invention is not limited to this, and the disclosure is omitted. Needless to say, it is also 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 further floor reaction force is added outside the configuration of the first embodiment and the like. 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 the minor loop of the posture inclination control, and the 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 hardly affected by the floor shape deviation, and it is possible to eliminate the steady deviation. In other words, if the inclination of the actual floor is different from the inclination of the assumed floor, a floor reaction force deviation occurs, and even if an attempt is made to cancel it by feedback controlling the body and posture inclination to the target value, A steady state error remains as described with reference to FIGS. 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 earlier with reference to FIG. 9, since the correction rule includes an integral element, a steady-state deviation does not appear, and the integral element is used as a target floor reaction force moment (input) in the configuration of FIG. There was no interposition between the actual floor reaction force moment (output), that is, there was no intervening element between the moment and the actual floor reaction force. The reaction force also reacts immediately, so that there is no phase lag, and the system does not oscillate.

In 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 is obtained. You may modify only. In that case, since the inverse kinematics operation is not required, the operation amount is greatly reduced. In addition, when controlling the floor reaction force obtained by synthesizing all the floor reaction forces of each foot even in the two-leg supporting period, the operation is as in the embodiment, but if it is desired to independently control the floor reaction force of each foot, What is necessary is just to operate the interference angle of each foot with respect to the foot. However,
Since control interference between the legs occurs, the controllability is not very good.

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. In general, the floor reaction force is represented by a force, a moment, and a point of action, or a ZMP, a force acting on the ZMP, and a moment in a direction normal to the floor. Regardless of the expression, not all components are involved in attitude control, so only necessary elements need to be obtained. The model may output only what is necessary. If the floor reaction force is expressed using the desired ZMP of the desired gait as a reference point of action, the force component hardly affects the behavior of the posture and 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 action point is a part of the robot, for example, an ankle (ankle joint 18,
20R (L)). That is, if the ankle moment is used instead of the floor reaction force moment in the embodiment, the control of the ankle moment is realized.

In the above configuration, the angle between the actual floor surface and the assumed floor surface is defined as an angle. However, the angle is not limited to this, and may be, for example, a step. However, in the above-described configuration, even if the difference is actually a step, the estimation amount is estimated as a difference in average inclination. If the characteristics of the actual floor surface can be grasped in advance that the inclination does not change but there is an uncertain step, or that the inclination angle changes smoothly without a step, the estimated amount is changed to a step accordingly. Or be inclined. When the inclination deviation is estimated as in the above configuration, the interference angle of the gait is corrected, but when the deviation of the step is estimated, the contact height of both legs may be corrected. Further, although the terms “tilt” and “tilt” mean the tilt angle, a tilt angular velocity or a value obtained by linearly combining the two may be used instead of the tilt angle.

Further, in the above configuration, 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. Is better. Even when the vertical floor reaction force is small or zero, such as during a swing phase or when a robot jumps, it is better to lower the correction gain or set it to zero. Further, the floor surface inclination estimation deviation may be set to 0 or may be gradually returned to 0.

In the one-leg supporting period, the limit at which a moment of floor reaction force can be generated is determined by the size of the foot contact surface and the vertical floor reaction force. Has characteristics. Naturally, the inverse compliance characteristic is also non-linear, and as the target floor reaction force increases, the interference angle, which is the output, sharply increases. Since it is not preferable that the interference angle of the actual robot becomes too large,
It is better to provide a limiter for the interference angle 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 suddenly 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-described configuration is also changed according to the walking period, the accuracy of estimating the floor shape deviation increases. .

Although the compliance model shown in the above-described configuration gives only the spring characteristics and does not take damping characteristics into consideration, a model taking damping characteristics into consideration is set for a robot having damper characteristics. May be.

In the above-described configuration, since the inclination of the floor is estimated, if it is known that the change in the inclination is gentle, the inclination of the floor in the next step is predicted and the next step is estimated. The desired gait itself may be changed in real time to a gait that matches the estimated inclined floor surface.

Further, in estimating the floor inclination deviation, even if the floor reaction force fluctuates after the estimated deviation converges by the correction law, the estimated deviation should not fluctuate. If they are different, when the floor reaction force fluctuates, the correction of the estimated deviation malfunctions, and the estimated deviation also fluctuates. Since the correction rule is composed of an integral and a low-pass filter element, the malfunction may cause a delay in the floor reaction force control, and in the worst case, oscillation may occur. To prevent this, adaptive control may be performed to match the compliance model to the identified value while identifying the compliance of the actual robot. In adaptive control, usually
Observe the fluctuation of the estimated floor reaction force output from the compliance model when the actual floor reaction force fluctuates.
It is identified so as to match the variation of the real robot.

Further, although the above description has been made with reference to a bipedal legged mobile robot 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, the present invention is applicable to other types of mobile robots such as a wheel type and a crawler type.

[0048]

According to a first aspect of the present invention, there is provided a walking control device for a link-type legged mobile robot having an upper body and a plurality of legs, wherein the robot is modeled by rigid links to perform walking. A first means for setting a target gait for walking on the assumed floor surface assuming a planned floor surface, a second means for detecting a posture inclination when the robot actually walks, A third means for obtaining a posture of the robot assuming that there is no behavior or deformation due to compliance given to the robot from the detected posture inclination, and obtaining a relative positional relationship between the obtained posture and the assumed floor surface; ,
Fourth means for estimating a floor reaction force and / or moment when the posture is changed from the obtained relative positional relationship by the compliance given to the robot so that the leg portion comes into contact with the assumed floor surface, Fifth means for determining the actual floor reaction force and / or moment of the robot, determining a deviation between the estimated floor reaction force and / or moment and the actual floor reaction force and / or moment, and based on the determined deviation Since it is configured to include the sixth means for correcting the assumed floor and the seventh means for correcting the target gait based on the corrected assumed floor, the floor assumed in the target gait can be corrected. Even when there is a difference in shape such as the angle from 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 the walking control device for a link type legged mobile robot having an upper body and a plurality of legs, the robot is modeled by rigid links,
First means for setting a desired gait for walking on the assumed floor, assuming a floor to be walked, and second means for detecting a posture inclination when the robot actually walks A position of the robot is obtained from at least the detected posture inclination, assuming 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. A characteristic in which a floor reaction force and / or a moment when a posture is changed by the compliance given to the robot so that the leg portion comes into contact with the assumed floor surface based on the obtained relative positional relationship. A fourth means for estimating according to
Fifth means for determining an actual floor reaction force and / or moment of the robot, and determining a deviation between the estimated floor reaction force and / or moment and the actual floor reaction force and / or moment, based on the determined deviation Since the configuration is such that the sixth means for correcting the assumed floor surface is provided, the walking of the robot is stopped, for example, in accordance with the difference in shape between the assumed floor surface and the actual floor surface, while having a simpler configuration, This makes it possible to prevent the posture from becoming more unstable.

According to a third aspect of the present invention, in the walking control apparatus for a link type legged mobile robot having an upper body and a plurality of legs, the robot is modeled by rigid links,
First means for setting a desired gait for walking on the assumed floor, assuming a floor 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 obtaining a first relative positional relationship between the obtained posture and the assumed floor surface, an actual floor reaction force of the robot and / or A fourth means for determining the moment,
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 in accordance with preset characteristics, the first and second means. Sixth means for obtaining a deviation of the relative positional relationship and correcting the assumed floor based on the obtained deviation, and seventh means for correcting the target gait based on the corrected assumed floor With such a configuration, the same effects as those described in claim 1 can be obtained.

According to a fourth aspect of the present invention, in the walking control device for a link type legged mobile robot having an upper body and a plurality of legs, the robot is modeled by rigid links.
First means for setting a desired gait for walking on the assumed floor, assuming a floor 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 obtaining a first relative positional relationship between the obtained posture and the assumed floor surface, an actual floor reaction force of the robot and / or A fourth means for determining the moment,
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 in accordance with preset characteristics, and the first and second means. Find the deviation of the relative positional relationship of
Since the apparatus is provided with the sixth means for correcting the assumed floor based on the obtained deviation, the same effect as described in claim 2 can be obtained.

According to a fifth aspect of the present invention, the third means is configured to obtain the posture of the robot from the detected posture inclination and the detected value of the joint displacement 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.

According to a sixth aspect of the present invention, the third means is configured to determine the posture of the robot from the detected posture inclination and the joint displacement command value of the link of the robot. The same effect can be obtained with a simple configuration.

According to a seventh aspect of the present invention, the third means is configured to determine the posture of the robot based on the detected posture inclination and a weighted average value of the joint displacement detection value and the joint displacement command value of the link of the robot. Is obtained, for example, it is possible to use the command value of the joint having a low contribution to the compliance operation as it is, and to achieve the same effect while reducing the amount of calculation.

According to claim 8, the sixth means is configured to correct the virtual floor using a correction rule including an integral element, so that the steady-state error can be made close to zero. .

According to a ninth aspect of the present invention, the seventh means includes feedback control means for correcting the desired gait so that the obtained actual posture inclination becomes a desired value. When the assumed floor surface is corrected using the correction rule including the element, the steady-state deviation can be made close to zero, and the correction rule is set such that if the gain of the joint displacement control system is high, the target floor reaction force and the actual floor Since there is no intervening force between the reaction force and the reaction force, the system does not become unstable due to phase lag.

[Brief description of the drawings]

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

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

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

FIG. 4 is a flowchart showing the operation of the first embodiment.

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

FIG. 6 is an explanatory diagram showing an operation of a mechanical compliance mechanism proposed by the present applicant in relation to an interference angle.

FIG. 7 is an explanatory view showing a state where 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 are the basis of the present invention, obtained from FIGS. 6 and 7.

FIG. 9 is a block diagram showing a state approximating the block diagram of FIG. 3;

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

FIG. 11 is a flowchart 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 flowchart 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 flowchart 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.

FIG. 19 is an explanatory diagram showing a steady state deviation when the posture is recovered in the state of FIG. 18;

[Explanation of symbols]

Reference Signs List 1 legged mobile robot (biped robot) 2 leg link 10R, 10L leg rotation joint 12R, 12L waist roll direction joint 14R, 14L waist pitch direction joint 16R, 16L knee pitch direction Joints 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 100 Mechanical compliance mechanism

Claims (9)

(57) [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 rigid links and assuming a floor on which walking is planned, and setting a target gait for walking on the assumed floor; b. Second means for detecting a posture inclination when the robot actually walks; c. From at least the detected posture inclination, a posture of the robot is obtained assuming 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 moment when the posture is changed so that the leg portion comes into contact with the assumed floor by the compliance given to the robot is estimated in accordance with a preset characteristic. Fourth means, e. Fifth means for determining the actual floor reaction force and / or moment of the robot; f. Sixth means for determining 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 based on the determined deviation; and g. Seventh means for correcting the target gait based on the corrected assumed floor surface. A walking control device for a legged mobile robot, comprising: 2. 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 rigid links and assuming a floor on which walking is planned, and setting a target gait for walking on the assumed floor; b. Second means for detecting a posture inclination when the robot actually walks; c. From at least the detected posture inclination, a posture of the robot is obtained assuming 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 moment when the posture is changed so that the leg portion comes into contact with the assumed floor by the compliance given to the robot is estimated in accordance with a preset characteristic. 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. 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 rigid links and assuming a floor on which walking is planned, and setting a target gait for walking on the assumed floor; 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 from the obtained actual floor reaction force and / or moment in accordance with preset characteristics, f. Calculating a deviation between the first and second relative positional relationships;
Sixth means for correcting the assumed floor based on the obtained deviation; and g. Seventh means for correcting the target gait based on the corrected relative floor surface, the walking control device for a legged mobile robot, comprising: 4. A walking control device for a linked legged mobile robot having an upper body and a plurality of legs, comprising: a. First means for modeling the robot with rigid links and assuming a floor on which walking is planned, and setting a target gait for walking on the assumed floor; 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 from the obtained actual floor reaction force and / or moment in accordance with preset characteristics, and f. Calculating a deviation between the first and second relative positional relationships;
A walking control device for a legged mobile robot, comprising: sixth means for correcting the assumed floor surface based on the obtained deviation. 5. The apparatus according to claim 1, wherein the third means obtains the posture from the detected posture inclination and a detected value of a joint displacement of the link of the robot. The walking control device of the legged mobile robot according to the above. 6. The apparatus 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. The walking control device of the legged mobile robot according to the above. 7. The robot according to claim 6, wherein the third means obtains the posture from the detected posture inclination, and a weighted average value of a joint displacement detection value and a joint displacement command value of the link of the robot. Item 5. The 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 apparatus according to claim 1, wherein said seventh means includes feedback control means for correcting said desired gait such that the obtained actual posture inclination becomes a desired value.
Item 7. The walking control device for a legged mobile robot according to any one of items 5 to 8.