JP2997038B2 - Walking control device for legged mobile robot - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a walking control device for a legged mobile robot, and more specifically, to a legged mobile robot such as a bipedal walking robot.
The present invention relates to a walking control device for a legged mobile robot that changes a gait to restore the stability of a posture when the posture of the robot collapses.

(Problems to be solved by conventional technology and invention) One of the methods for stabilizing the walking of the legged mobile robot is as follows.
In some cases, the state of the robot is detected during walking, the gait of the robot is determined according to the detected amount of state, and where the next step is to be placed is calculated in real time for walking. An example of actually walking a robot according to this method is, for example, "Legged Robots on Rough Terrain: Experiments i
n Adjusting Step Length: IEEE 1988, by Jessica Hodgi
ns ".

However, in this type of technology, after recognizing the state of the robot, a very complicated determinant is solved to determine the gait, the next optimal landing position is calculated, and the swing leg is actually converted to that position. Since a series of processes for driving to a position were performed in real time, the determinant became large in a complex bipedal legged mobile robot having six degrees of freedom on one leg, for example. Either a very large and high-performance one is required, or the mechanism of the robot itself must be simplified, in other words, the degree of freedom of the legs must be reduced to reduce the burden on the computer. For example, the above real-time processing was difficult.

On the other hand, as one of the methods for walking the robot, the optimal value of each joint angle of the robot is calculated in advance with a large computer, and the resulting gait is stored in the computer equipped with the robot, A method of outputting during walking to walk is also proposed.
-97006 can be mentioned. According to this method, since the gait calculation itself is performed offline, it may take a long time. Therefore, even if the robot has a large degree of freedom, the load on the on-board computer is extremely reduced, and the gait is small, light, and low. A computer that is low in price and consumes little power is sufficient.

However, the biggest drawback of this method is that the gait is set in advance, so that it is impossible to cope with a case where the actual walking conditions are different from the set conditions. If there are unexpected irregularities in the place where the person actually walks, the robot receives a reaction force of a magnitude different from the expected reaction force at an unexpected timing, and if the difference is large, the walking posture is disturbed. If the turbulence exceeds the physical limit to compensate for the bottom area of the sole of the robot, the robot falls.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned drawbacks and to provide a walking control device for a legged mobile robot having the advantages of the above two methods. It is another object of the present invention to provide a walking control device for a legged mobile robot which can easily change a set gait to restore walking stability when unexpected walking conditions are encountered during actual walking.

Furthermore, when the target gait is set in advance offline, not only when the joint angle is set in detail as described above, but also with higher-level conceptual walking data such as a landing position or a center of gravity position. In addition, when taking a method of determining a gait in real time during walking, it is unavoidable that a sudden change in walking conditions is encountered and the gait must be changed.

Therefore, a second object of the present invention is to make it possible to easily change a gait immediately in response to an unexpected change in walking conditions, regardless of whether walking data is set in advance offline. An object of the present invention is to provide a walking control device for a robot.

Means for Solving the Problems In order to achieve the above-mentioned object, according to the present invention, for example, according to claim 1, a base and a plurality of leg links respectively connected thereto and provided with at least one joint are provided. In the walking control device for a legged mobile robot, the joints of the leg links are configured such that the robot assumes a posture that realizes the gait based on a preset walking pattern that determines the gait of the robot. First to determine drive control value
Control value determining means, gait change instructing means for instructing a change in the set gait, when a change in gait is instructed, the gait pattern is corrected, and the leg is corrected based on the corrected gait pattern. Second to determine the joint drive control value of the head link
Control value determination means, and an actuator for driving the joint based on the joint drive control value determined by any of the first and second control value determination means, and the second control value determination means Is configured such that after the robot takes a predetermined posture, the walking pattern is determined so as to realize the changed gait.

(Operation) The gait is set, the joint drive control value is determined so that the gait can be obtained, and when the gait needs to be changed, the control value is corrected so as to obtain the changed gait. Since the leg link passes through the predetermined posture, the gait can be corrected and easily recovered even when the posture collapses due to an unexpected road surface condition. In addition, since the gait is configured so as to take a predetermined posture once when changing the gait, the change in the gait is smooth, and no special angle correction value for connecting the posture is required. Otherwise, the data amount can be reduced.

(Example) Hereinafter, an example of the present invention will be described using a bipedal walking robot as an example of a legged mobile robot. FIG. 1 is an explanatory skeleton diagram showing the robot 1 as a whole, and has six joints (axes) on the right and left legs. The six joints (axes) are, in order from the top, joints (axes) 10 for hip rotation.
R, 10L (R is the right side, L is the left side; the same applies hereinafter), joints (axis) 12R, 12L in the waist pitch direction, joints (axis) 14R, 14L in the same roll direction, joints in the knee pitch direction (Axis) 16R, 16
L, the joints (axes) 18R, 18L in the pitch direction of the ankle, and the joints (axes) 20R, 20L in the same roll direction, with the feet 22R, 22L attached to the lower part, Is provided with a body (base) 24, in which a control unit 26 is stored.

In the above, the hip joint is a joint (axis) 10R (L), 12R
(L) and 14R (L), all of whose axes are 1
It is configured to intersect at points. Also joint (axis) 18R
The axis of the ankle joint composed of (L) and 20R (L) is also orthogonal to each other, and the three pitch direction joints (axis) 12R (L), 16R (L) and 18R (L) are arranged in parallel with each other, and their relative positional relationship does not change regardless of the behavior of other joints (axes). As shown in the figure, six degrees of freedom are provided for one leg, and the foot 22R (L) can be placed at any position and in any direction even if the body 24 is fixed. That is, by driving each of these 6 × 2 = 12 joints (axes) to an appropriate angle during walking, a desired movement can be given to the entire leg, and walking in a three-dimensional space arbitrarily. Can be. The thigh link 27R between the hip joint and the knee joint,
At 27L, the knee joint and the ankle joint are connected by lower leg links 28R and 28L.

These joints are mainly composed of an electric motor and a speed reducer that boosts its output. The details of the portion below the knee joint will be described below with reference to FIGS. 2 and 3, but the hip joint has a similar structure. In addition, since it is a left-right object, the following description is made on the right leg side. In FIGS. 2 and 3, the output of an electric motor (not shown) attached to the middle position of the thigh link 27R is output from the harmonic reducer 84 attached to the knee joint (shaft) 16R via the belt 82. Input to the input axis. Also, a concave portion 87 is formed on the upper end side of the lower leg link 28R, an electric motor 88 is housed in the concave portion 87, and the output thereof is input to a harmonic reducer 92 arranged at the ankle via a belt 90, and the foot 22R is It is driven in the pitch direction about the axis 18R. The foot 22R is configured to be swingable in the roll direction about the axis 20R that is orthogonal to the axis 18R, so that the harmonic reducer 94 and the electric motor 96 that supplies power thereto are directly connected. Provided. Each electric motor is provided with a rotary encoder and detects the rotation angle of the motor shaft (only a rotary encoder 89 for the electric motor 88 is shown in the figure).

Thus, a six-axis force sensor 98 is provided at the ankle, and separates the x, y, z three-directional components of the force transmitted to the robot via the foot and the three-directional components of the moment separately. Measurement is performed to detect the presence or absence of landing on the foot and the magnitude and direction of the force applied to the support leg. A known grounding switch 99 is provided at each of the four corners of the sole, which is formed substantially flat and has an elastic material 220 such as rubber to absorb an impact at the time of landing, and detects the presence or absence of grounding (secondary state). The illustration is omitted in FIGS. 3 to 3). Further, as shown in FIG. 1, a pair of inclination sensors 100 and 102 are provided at appropriate positions of the body 24, and an angle with respect to the z axis in the xz plane and its angular velocity, and similarly, a z in the yz plane Detect the angle to the axis and its angular velocity. These outputs are sent to the control unit 26 in the body 24 described above.

FIG. 4 is a block diagram showing details of the control unit 26, which is constituted by a microcomputer. The outputs of the tilt sensors 100 and 102 are converted into digital values by an A / D conversion circuit 104, and the output is sent to a RAM 10 via a bus 106.
Sent to 8. The output of the encoder 89 etc.
Through the RAM 108 and a ground switch 99.
Are similarly stored in the RAM 108 via the waveform shaping circuit 112. A CPU 114 is provided in the control unit, and as described later, the CPU 114 reads stored walking data, calculates a speed command value from a deviation from an actually measured value sent from the counter 110, and performs D / A conversion. The position control is transmitted to the servo amplifier 120 via the circuit 118 to realize the position control. As shown in the figure, the encoder output is sent to the servo amplifier via the F / V conversion circuit 122, and the speed feedback control as a minor loop is realized. The sign
Reference numeral 128 denotes a joystick for commanding a gait change such as a course and a stride, reference numeral 130 denotes an origin switch for determining an origin (upright) posture, and reference numeral 132 denotes a limit switch for preventing overrun.

Hereinafter, the operation of the control device will be described with reference to the flowchart of FIG. In the control shown in the figure, it is assumed that the target joint angle is set in advance off-line, and virtual compliance control ("virtual compliance control of a multi-degree-of-freedom robot") in which impedance control is realized by speed-resolved control. (Transactions of the Society of Instrument and Control Engineers, VOL.22, NO.3, March 1986)).

First, after initializing each part of the apparatus in S10, a walking pattern nθi is searched in S12 (a gait determined from this walking pattern is referred to as a “standard gait” in this specification). This indicates a target value of each joint angle when the robot walks on a road surface that is ideally flat and has uniform hardness. Here, the subscript i indicates the number of the joint, and the subscript indicates the angle at time n. The number of the joint is 18L in order from the bottom for the left foot
= 1,20L = 2, .. 12L = 6, and for the right foot, from top to bottom
It is assumed that 12R = 7, 14R = 8,... 18R = 12. These time series data are calculated in advance by a large-sized computer and stored in the ROM 116 of the microcomputer in the control unit.

Subsequently, parameters kp, kv ... are input in S14. These are feedback gains and will be described later in detail. Subsequently, in S16, the timer value n, the counter value Count, and the joint number (counter) value i are reset to zero, and in S18, walking is started.
At 20, the value of the joint number i counter is set to 1. Then S2
The joint angle nθi (i
= 1) and other parameters are read from the memory. Where n
+ 1θi indicates the time after the current time t, that is, the target joint angle at the time of starting the next program. FIG. 6 shows an example of the walking pattern data (joint numbers 01 to
For 12, the target joint angle is set in advance for each time n, t, u, v. Offline. In S22, ωDt indicates a target inclination angular velocity (described later). Furthermore, Ft (ωw) is the period of both feet support, Ft
(Ωs) is one leg support period, Ft (C) is shock absorption control period, Ft
(T) is a gait switching period, and Ft (S) is a flag (described later) indicating a falling likely (falling risk) detection period. The flag is determined from the output of a six-axis force sensor or the like in the microcomputer described above. The bit is set to 1 when in the period.

Next, in S24, the detection value of the inclination sensor or the like is read. Here, iθR indicates the actual joint angle of the i-th joint, ωR indicates the actual inclination angular velocity, and M indicates the actual moment applied to the foot. Subsequently, in S26, it is determined from the above-mentioned flag whether or not it is in the detection period of falling. This will be described with reference to FIG. At the bottom of the figure, "HC" is the heel
"TO" means to-off, i.e., leaving the floor. Therefore, the period indicated by the solid line for the left and right feet is the stance period, the period indicated by the broken line is the swing period, and the period in which the solid lines overlap is the two-leg support period. In the embodiment, as shown in the drawing, the gait is switched in the swing phase, and the first half of the gait is detected as a fall detection period, and the risk of falling is detected to determine the corrected gait, and the corrected gait is corrected in the subsequent period. Is executed.

Here, the gait correction in this embodiment will be described. In this embodiment, as shown in FIG. 8, a plurality of preliminary landing positions are prepared in addition to the standard landing position. That is, the black circles in FIG. 8 indicate the landing positions expected by the walking pattern calculated by the large-scale offline computer shown in FIG. 6 in advance. Prepare the landing position, when the robot is about to fall, select the best landing position to recover the posture in it, change the gait to land there,
That is, the target joint angle is corrected to recover the posture stability.

Specifically, the detection of the possibility of falling (the possibility of falling) is performed by integrating the deviation between the target inclination angular velocity ωDT and the actual inclination angular velocity ωR as shown in FIG.
θ was obtained, and the gait was selected accordingly. That is, if the total sum is xθa in FIG. 9, the gait corresponding to the position orthogonal to the selection function is a, and therefore, the gait a (a) located slightly before the standard gait in FIG. Is selected, and the target joint angle is corrected so that the gait can be obtained. The details are shown in FIG. That is,
If the switching of the gait is determined after the ankle joint 20L (i = 01) is driven as t0θ01, t1θ01. To correct. At this time, not only the ankle joint 20L but also all or a part of the remaining 11 joints are corrected, and in the illustrated example, 18L, 16L, 12L, 12R, 16R, and 18R are corrected.

It should be emphasized here that the walking pattern that determines or defines the corrected (changed) gait is configured to realize the changed gait after the robot 1 has taken a predetermined posture. At the beginning of the gait switching period (No.
In FIG. 10, “tiθna”) promises to output a predetermined reference attitude. That is, the gait is switched to the corrected gait after passing through the posture as shown in FIG. 11 once. This configuration is to prevent the number of gaits calculated in advance and stored in the memory of the computer from increasing in proportion to the square of the landing position as the number of preliminary landing positions increases. That is, in the example shown in FIG. 8, 25 landing positions are prepared, but this is a case where the standard gait is changed first from the standard gait. In the next landing, the gait a may be corrected to the gait b at the next landing, and the gait c may be corrected at the next one step. That means that if you prepare 25 candidate points for one landing, 25 landing positions where the next step may land from the 25 landing positions where your feet may be currently placed Considering all combinations of gaits for landing a free leg on a position, 25 × 25 = 625 gaits must be set in advance. In consideration of this point, in the present embodiment, a predetermined reference posture is once taken at the time of switching,
That is, the joint angle is once reset to a predetermined angle and then corrected. With this configuration, it is possible to suppress an increase in the number of gaits to be set in advance.

Returning to the flow chart of FIG. 5 again, when it is determined in S26 that it is in the detection period of falling down, the integrated value of the inclination angular velocity, that is, the sum xθ, y of the inclination angles is determined in S28 as described above.
Find θ. If not, the sum is set to zero in S30. Next, in S32, it is determined whether or not it is in a gait switching period, and when affirmative, the process proceeds to S34, in which a gait is selected according to the sum xθ, yθ, and the corrected target joint angle of the gait selected in S36. Is read.

Next, the position feedback control value iV1 is calculated in S38, and the speed feedback (forward) is performed in S40.
The control value iV2 is calculated. That is, as shown in FIG. 12, the deviation Δ between the joint angle command value nθi and the actual joint angle iθR
a position feedback value obtained by multiplying θ by a proportional gain kp;
A speed command value obtained by adding a feedforward value obtained by multiplying a gain by a deviation between the joint angle command value nθi at the current time and the joint angle command value n + 1θi at the next time is output to the servo amplifier 120. FIG. 12 is a block diagram of the joints excluding the ankle joint, and control values and the like based on the compliance control are fed back to the ankle joint as shown in the block diagram of FIG. 13, which will be described later. .

Subsequently, in S42, it is determined whether or not it is an ankle joint. When the result is affirmative, the process proceeds to S44 and thereafter, and first, the inclination angular velocity feedback and the like are performed. Specifically, first, the flags are set in S44 to S46.
Bit on of Ft (ωw) or Ft (ωs), that is, whether it is a two-leg support period or a one-leg support period, is determined, and S48 is performed based on the determination result.
Alternatively, in S50, as shown in FIG. 13, the third speed feedback control value iV3 is calculated by multiplying the gain kω by the deviation Δω between the target tilt angular speed ωDt and the actual tilt angular speed ωR. That is, in the present embodiment, there is a danger that the robot will fall when the inclination angular velocity deviates from the target value in conjunction with the compliance control with the aim of further stabilizing walking, or a moment is applied to the ankle joint from outside. Judge that
The deviation is multiplied by an appropriate gain kω to drive the ankle joint of the leg on the landing side to generate a ground contact force, thereby correcting the collapse of the posture of the robot. When it is determined in the flowchart of FIG. 5 that neither the both-leg support period nor the one-foot support period is present, the control value is set to zero in S52.

Subsequently, the virtual compliance control value is determined in S54 and subsequent steps. That is, the joint driving speed is controlled in accordance with the moment acting on the ankle joint to reduce the impact at the time of landing. Specifically, a predetermined time T until the free leg of the robot gets off the floor and landed on it.
COMP is set as the shock absorption control period, and when it is determined in S54 that the period is within the period, the process proceeds to S56, where the gain kc is changed to kc = k
_COMP × f (Count) is calculated, a fourth speed feedback value iV4 is calculated by multiplying the moment M detected in S58 (FIG. 13), and when a landing is detected in S60, the counter value is incremented in S62. . As described above, the gain of the shock absorption is set as a function of the counter value COUNT, and is gradually reduced with time upon landing, and is finally set to zero.
If it is determined in S54 that it is not in the shock absorption control period, the process proceeds to S64.
Resets the control value iV4 to zero, and resets the counter value to zero in S66.

Subsequently, all the control values calculated in S68 are added to obtain the sum iVC
The OMM is obtained and output to the servo amplifier 120, the value of the joint number counter is incremented in S70, it is determined whether or not the last joint has been exceeded in S72, and if affirmative, the next target joint angle is searched in S74. In step S76, the control value is continuously determined for each joint unless it is determined in step S76 that walking has ended.

In the present embodiment, as described above, in addition to the standard gait, the present embodiment determines a preset gait as described above, and a landing position corresponding to the gait for each landing of the leg link, as described above. First control value determining means for determining a joint drive control value of the leg link to land on a landing position corresponding to the gait based on a walking pattern including a plurality of landing candidate positions including: And a second control value determining means for selecting any one of the plurality of landing candidate positions and determining a joint drive control value of the leg link to land at the selected position when the change is instructed. It was configured as follows. That is, in addition to the standard gait, when it is determined that the robot is likely to fall, the optimal gait is selected from the prepared gaits. Therefore, since the standard gait is calculated in advance, the load on the on-board computer is reduced in that respect, and since the gait for which the landing position is changed is also calculated in advance, those data are stored in the on-board computer. It is sufficient to let the user select the optimal gait from among them according to a predetermined procedure.As a result, it is possible to ensure sufficient real-time performance even with a low-level computer, and to create a robot with multiple degrees of freedom. You can walk stably.

As is well known, when designing the gait, it is general to divide the motion into two in-plane motions of a plane in the traveling direction and a plane in the left-right direction, calculate the motion, and combine the motions again after the calculation.
When using that method, the number of landing candidate positions described above is
Instead of 25, 9 would be enough. However, according to this method, the accuracy of the gait decreases as the distance from the standard gait increases, such as the right front or the left rear, so that the error becomes an error. If you have more candidate points, you will have the ability to respond to large changes in the situation, so if you generalize this idea to have m candidate points before and after the standard position and n candidate points on the left and right, accurate gait Is required, the total number of gaits to be stored is m × n = mn. However, if a small error is accepted, m + n-1 will suffice. According to this, even if the number of candidate points increases in the future, the storage capacity of the computer can be greatly reduced. Further, the candidate points may be linked to each other by a method such as linear interpolation, or a gait corresponding to a finite number of landing positions stored in advance from a gait corresponding to an arbitrary landing position may be interpolated or extrapolated. The contents may be interpolated as necessary to save the storage capacity.

Further, the gait is switched so as to pass through the reference posture shown in FIG. 11 so as to save the storage capacity. However, in this embodiment, this reference posture is shown only by an angle. However, the reference posture may include the angular velocity in addition to the angle, and further include the angular acceleration,
The gait may be switched after passing through that state.

FIG. 14 shows a second embodiment of the present invention. In the case of the first embodiment, a plurality of landing points were prepared, and all the joints were corrected to select one of them and land there, but in the case of the second embodiment, when a danger of falling was detected. As shown in the figure, the hip and ankle joints of the joints were modified to restore the posture stability.

Specifically, in S34 of the flow chart of FIG. 5, the correction angle δθ is determined based on the determination function shown in FIG. 15 in accordance with the sum xθ, yθ of the integrated values of the inclination angles, and the hip joint and the ankle joint are determined by this δθ. Correct by adjusting the joint angle. Specifically, if the sum is a value in the x direction, that is, xθ, the joints in the pitch direction (12L (R), 18L (R)) are corrected,
If Δθ determined in FIG. 15 is a positive value, the value is added, and if Δθ is a negative value, the value is subtracted. FIG. 16 shows the corrected data. Although only the correction in the pitch direction is shown in the figure, the correction in the roll direction is also the same, and δθ is obtained from yθ according to the same or similar function as the decision function in FIG.
L (R)).

Here, when switching the gait, if the gait is switched from the initially set standard gait to the above-described corrected gait at once, the realization of smooth walking is impaired, so the gait is gradually corrected as shown in FIG. I did it. In the example shown in FIG. 16 and FIG. 16, the correction is made in five steps. This is the same when the stability of the posture is restored and the normal gait is returned again.

In the case of the second embodiment, it is not necessary to prepare a plurality of landing positions, and since only a part of the joints to be corrected is sufficient, the posture can be more easily adjusted even when the set walking data encounters an unexpected change in condition. It can correct the collapse and restore a stable posture. In the case of the second embodiment as well, it is assumed that the gait passes through the reference posture once during the gait switching period.
As a result, the gaits to be stocked need only be independent time-series joint angle data, and no special connection joint angle data is required, so that the storage capacity can be saved.

FIG. 18 is an explanatory view showing a third embodiment of the present invention. The difference from the first embodiment is that the correction of the angle is obtained by multiplication or division instead of addition and subtraction. That is, as shown in the figure, according to the total sum xθ (yθ), the correction coefficient is determined to be k1, k2 when it is a positive value, and 1 / k1, 1 / k2 when it is a negative value. Is modified by multiplying the joint angle in the pitch (roll) direction. FIG. 19 is an explanatory diagram showing the correction. Also in the case of the third embodiment, as shown in FIG. 20, the gait is increased with time to realize a smooth gait change.

In the third embodiment and the second embodiment described above, an example is shown in which the correction amount is multiplied (divided) and added (decreased), that is, corrected using a linear function. In terms of the pitch direction, nθiREV = nθiSTD × Axθ + Bxθ∵nθiREV: changed gait joint angle, nθiSTD: standard gait joint angle, and A and B: constants.

In any case, various modifications are possible in the second and third embodiments. For example, the direction of the correction amount is changed according to the sign of the sum and the size is made the same, but they may be independently determined. In the third embodiment, another correction coefficient may be used instead of division. Further, the function need not be a linear function, and may be determined using, for example, fuzzy inference.

Further, in the above-described first to third embodiments, the danger of overturning (appearing to fall) is calculated from the inclination angle. However, the present invention is not limited to this, and the inclination angle speed may be used. May be calculated, and when the movement speed of the locus of the action point moves faster from the heel-equivalent part to the toe-equivalent part than in the normal case, it may be determined to fall forward.

In each of the above embodiments, only the joint on the free leg side is targeted for correction. However, the present invention is not limited to the free leg. For example, the joint on the standing leg side and the joint on the free leg side may be corrected equally.

Furthermore, although the method of calculating the target joint angle offline in advance is premised, the present invention is not limited to this, and similarly, even when the target data is set offline,
It is also appropriate when using a higher concept such as a landing position or a position of the center of gravity, and even when a method of determining a gait in real time is assumed, sudden changes in road surface conditions can be performed as long as circumstances permit. That is reasonable.

Although the present invention has been described with respect to a bipedal legged mobile robot, the present invention is not limited thereto, and is applicable to a legged mobile robot having three or more legs.

(Effect of the Invention) The walking control device for a legged mobile robot according to claim 1, wherein the robot assumes a posture in which the robot realizes the gait based on a preset walking pattern that determines a gait of the robot. As described above, the first control value determination means for determining the joint drive control value of the leg link, the gait change instruction means for instructing the change of the set gait, when the gait change is instructed, Second control value determining means for correcting the walking pattern and determining a joint drive control value of the leg link based on the corrected walking pattern; and the first and second control values.
And an actuator for driving the joint based on the joint drive control value determined by any of the control value determination means, and the second control value determination means, after the robot takes a predetermined posture, Since the configuration is such that the walking pattern is determined so as to realize the changed gait, it is possible to correct the gait in response to a change in walking conditions and to rebuild the posture, thereby realizing stable walking. Can be. In addition, since the leg link passes through the reference posture and changes the gait, the change in posture is smoothly continuous and, for example, when the gait is stored in advance as data, special connection data is used. And the amount of data can be reduced, and as a result, a control device can be realized using a relatively low-level computer.

3. The walking control device for a legged mobile robot according to claim 2, wherein a plurality of landing candidate positions including a landing position corresponding to the gait for each landing of the leg link for determining a preset gait. A first control value determination unit that determines a joint drive control value of the leg link to land at a landing position corresponding to the gait based on a walking pattern including: Gait change command means to command,
A second control value determining means for selecting one of the plurality of landing candidate positions when a gait change is instructed and determining a joint drive control value of the leg link to land at the position; And an actuator for driving the joint based on the joint drive control value determined by any of the first and second control value determination means, so that the set gait may change unexpectedly. When the controller is encountered, the posture can be quickly re-established, and stable walking can be continued.Also, when the control device is realized by a computer, data calculated offline is stored in advance, and the data can be selected and output in a timely manner. For simplicity, it can be configured at a relatively low level.

4. The walking control device for a legged mobile robot according to claim 3, wherein a plurality of landing candidate positions including a landing position corresponding to the gait for each landing of the leg link for determining a predetermined gait. A first control value determination unit that determines a joint drive control value of the leg link to land at a landing position corresponding to the gait based on a walking pattern including: Gait change command means to command,
When a gait change is instructed, an arbitrary landing position is generated by interpolation and extrapolation from the finite number of landing positions, and a joint drive control value of the leg link is determined so as to land at that position. The second control value determination means and the actuator for driving the joint based on the joint drive control value determined by any of the first and second control value determination means are provided. Even when unexpected gait encounters unexpected changes, the posture can be quickly reestablished and stable walking can be continued.Also, when the control device is implemented by a computer, data calculated offline is stored in advance. Since it is only necessary to select and output in a timely manner, it can be configured with a relatively low level.

5. The walking control device for a legged mobile robot according to claim 4, wherein the second control value determination unit is configured to perform the change after the robot takes a predetermined posture when a change in gait is instructed. Since the joint drive control value is determined so as to realize a proper gait, the number of gaits to be set can be effectively reduced, and the load on the computer can be further reduced. Also, a smooth change can be realized when the posture changes. Thus, the number is more specifically configured as described in claim 5.

The walking control system of a legged mobile robot according to claim 6, wherein
Since the joint drive control value determining means is configured to determine the joint drive control value so that the gait is smoothly changed over time, the gait can be changed smoothly even when changing the gait. Thus, more stable walking can be realized.

The walking control device for a legged mobile robot according to claim 7, wherein the control value correcting means is configured to correct the control value in a predetermined period during one cycle of the gait. The gait can be clearly switched, the gait can be switched in a timely manner, and more stable walking can be realized.

9. The walking control device for a legged mobile robot according to claim 8, wherein the gait change command means includes an inclination angle n of at least one of the base and the leg link with respect to a vertical axis.
A detecting means for detecting a next differential value, instructing a change of the gait when the detected value is equal to or more than a predetermined value, a danger of falling of the robot can be reliably detected, and the posture is reestablished accordingly. And stable walking can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the entire walking control device of a legged mobile robot according to the present invention, FIG. 2 is an explanatory side view showing a portion below a knee joint in FIG. 1, and FIG. III is a partial cross-sectional view, FIG. 4 is an explanatory block diagram of the control unit, FIG. 5 is a flowchart showing the operation of the control device, and FIG. 6 is a walking pattern (standard gait) preset offline.
FIG. 7 is an explanatory diagram showing the swing phase and the stance phase of the left and right feet on the time axis, and showing a fall detection period and a corrected gait output period therein, and FIG. 8 is a landing candidate. FIG. 9 is an explanatory diagram showing a position, FIG. 9 is an explanatory diagram showing a selection function of a corrected gait, and FIG. 10 is a diagram showing correction of the walking pattern of FIG.
FIG. 10 (A) is a partial view of FIG. 10 showing the component A of FIG. 10, and FIG. 10 (B) is a diagram of FIG. FIG. 10 is a partial view showing the component B of FIG. 10, and FIG.
10 (D) is a partial view of FIG. 10 showing a component D of FIG. 10, FIG. 11 is an explanatory view showing a reference posture, FIG.
The figure is a block diagram illustrating the control algorithm shown in the flowchart of FIG. 5 for the joints excluding the ankle joint.
FIG. 13 is a block diagram for explaining a control algorithm for the ankle joint, FIG. 14 is an explanatory diagram showing correction of control values in the second embodiment of the present invention, and FIG. FIG. 16 is an explanatory view showing the determination of FIG.
FIG. 17 is an explanatory diagram showing the correction of the walking pattern in FIG. 17, FIG. 17 is an explanatory diagram showing the temporal characteristics of the correction amount, FIG. 18 is an explanatory diagram showing the correction factor of the control value showing the third embodiment of the present invention, FIG. FIG. 19 is an explanatory view showing the correction of the walking pattern in FIG. 6 and FIG.
FIG. 13 is an explanatory diagram showing the time-dependent characteristics of the correction coefficient of the third embodiment. 1 ... Legged mobile robot (biped robot), 10R, 10
L ... Leg rotation joint (axis), 12R, 12L ... Crotch pitch direction joint (axis), 14R, 14L ... Crotch roll direction joint (axis), 16R, 16L ... Knee pitch joints (axes), 18R, 18L ... Ankle pitch joints (axes), 20R, 20L ... Ankle roll joints (axes), 22R, 22L ... feet , 24 ... body, 26 ... control unit, 27R, 27L ... thigh link, 28R, 28L ... lower leg link, 84, 92, 94 ... harmonic reducer, 82, 90 ... belt, 88, 96 …… Electric motor, 89… Rotary encoder, 87 …… Recess, 98 …… 6 axis force sensor, 99… Ground switch, 100,102 …… Tilt sensor, 104 …… A / D conversion circuit, 1
06 Bus, 108 RAM, 110 Counter, 112 Waveform shaping circuit, 114 CPU, 116 ROM, 118 D / A conversion circuit, 120 Servo amplifier, 122 F / V conversion circuit, 128
…… Joystick, 130 …… Origin switch, 132 ……
Limit switch,

Continuation of the front page (56) References JP-A-2-3582 (JP, A) JP-A-62-9705 (JP, A) JP-A-62-9706 (JP, A) (58) Fields studied (Int .Cl. ⁷ , DB name) B25J 5/00

Claims (8)

(57) [Claims] 1. A walking control device for a legged mobile robot comprising a base and a plurality of leg links respectively connected to the base and having at least one joint, comprising: a. First control value determining means for determining a joint drive control value of the leg link based on a walking pattern for determining a gait such that the robot assumes a posture for realizing the gait; b. Gait change instructing means for instructing a gait change; c. When a gait change is instructed, the gait pattern is corrected, and based on the corrected gait pattern, the joint drive control value of the leg link is changed. A second control value determining means for determining; and d. An actuator for driving the joint based on the joint drive control value determined by any of the first and second control value determining means. The second control value determining means determines the walking pattern so as to realize the changed gait after the robot has taken a predetermined posture, and the walking control device for a legged mobile robot is characterized in that . 2. A walking control device for a legged mobile robot comprising a base and a plurality of leg links respectively connected to the base and having at least one joint, comprising: a. Determining a landing pattern corresponding to the gait based on a walking pattern including a plurality of landing candidate positions including a landing position corresponding to the gait for each landing of the leg link; First control value determining means for determining a joint drive control value of the link; b. Gait change instructing means for instructing a change in the preset gait; c. When a gait change is instructed, Second control value determining means for selecting one of a plurality of landing candidate positions and determining a joint drive control value of the leg link to land at the position; and d. The first and second controls Determined by one of the value determination means A walking control device for a legged mobile robot, comprising: an actuator that drives the joint based on the joint drive control value. 3. A walking control device for a legged mobile robot comprising a base body and a plurality of leg links respectively connected to the base body and having at least one joint, comprising: a. Determining a landing pattern corresponding to the gait based on a walking pattern including a plurality of landing candidate positions including a landing position corresponding to the gait for each landing of the leg link; First control value determining means for determining a joint drive control value of the link; b. Gait change instructing means for instructing a change in the preset gait; c. When a gait change is instructed, A second control value determining means for generating an arbitrary landing position by interpolation and extrapolation from a limited number of landing positions and determining a joint drive control value of the leg link in order to land at that position; andd. The first and second control value determining means A walking control device for a legged mobile robot, comprising: an actuator that drives the joint based on the joint drive control value determined by any one of the above. 4. When the gait is commanded to change, the second control value determining means sets the joint drive so as to realize the changed gait after the robot takes a predetermined posture. 4. A control value is determined.
A walking control device for a legged mobile robot according to the above item. 5. The joint drive control value is calculated by dividing the robot into two in-plane motions, a surface in a traveling direction and a surface in a left-right direction. 5. The walking control device for a legged mobile robot according to claim 4, wherein the total number of the plurality of landing candidate points is m + n-1, where m is n in the direction and n is in the left and right direction. 6. The system according to claim 1, wherein said second joint drive control value determining means determines said joint drive control value such that said gait is smoothly changed with time. A walking control device for a legged mobile robot according to any one of claims 5 to 13. 7. The leg according to claim 1, wherein the control value correcting means corrects the control value during a predetermined period during one cycle of the gait. Walking control device for mobile robots. 8. The gait change instructing means includes detecting means for detecting an nth-order differential value of an inclination angle of at least one of the base body and the leg link with respect to a vertical axis, and the detected value is equal to or more than a predetermined value. The walking control device for a legged mobile robot according to any one of claims 1 to 7, wherein a command to change the gait is issued at the time.