JP2003236778A - Legged mobile robot and control method for the robot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow bipedal walking alternately raising right and left leg parts by four degrees of freedom for each leg. <P>SOLUTION: The leg parts 12L and 12R of a legged mobile robot 10 comprise, as four degrees of freedom, hip articulate pitch axes 19L and 19R, knee articulate pitch axes 20L and 20R, ankle articulate pitch axes 21L and 21R, and ankle articulate roll axes 22L and 22R. A control part 23 controlling these operations laterally moves a robot gravity center point P by the operations of the ankle articulate roll axes 22L and 22R of the right and left leg parts 12L and 12R and the operations of the pitch axes 19L, 20L, and 21L (19R, 20R, 21R) of one leg part 12L (12R). <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a legged mobile robot that walks bipedally while alternately lifting left and right legs, and more specifically, a legged mobile robot that realizes bipedal locomotion with a small degree of freedom, and a legged mobile robot thereof. Regarding control method.

[0002]

2. Description of the Related Art A legged mobile robot that walks on two legs while alternately lifting left and right legs has already been developed. This type of legged mobile robot has a merit of being able to walk on a step, although its structure and control are slightly more complicated than those of walking with the left and right legs grounded.

In the case of bipedal walking as described above, in order to ensure stability in the one-leg supporting period, the center of gravity of the robot is moved to the supporting leg side prior to the lifting operation of the stepping leg.
An action is required to move the center of gravity of the robot in the left-right direction. In addition, the "robot center of gravity" described in the present application is ZMP.
(Zero Moment Point: The point on the floor where the moment due to the floor reaction force becomes zero) is included.

[0004]

However, in the conventional legged mobile robot described above, since the center of gravity of the robot is moved in the left-right direction by the roll motion of the hip joint and the ankle joint in the left and right legs, at least one leg 5
Two degrees of freedom (hip joint pitch axis, hip joint roll axis, knee joint pitch axis, ankle joint pitch axis and ankle joint roll axis)
Need. As a result, real-time control that requires heavy processing such as coordinate calculation, motion calculation, and target trajectory calculation becomes difficult as the number of controlled objects increases, and the cumulative error of the joint increases and the operation accuracy increases. It may decrease.

An object of the present invention is to enable bipedal walking in which the left and right legs are alternately lifted with four degrees of freedom per leg, and as a result, the processing load on the control unit is reduced and real-time control is enabled. At the same time, it is an object of the present invention to provide a legged mobile robot and a control method thereof that can reduce the accumulated error in the joint portion and improve the operation accuracy.

[0006]

To achieve the above object, a legged mobile robot according to the present invention comprises a pair of left and right legs provided on a robot body, and a thigh of the leg portion with respect to the robot body. A hip joint that is moved in the pitch direction, a shin of the leg, a knee joint that is moved in the pitch with respect to the thigh, and a foot of the leg with respect to the shin. An ankle joint that is operated in the pitch direction and a roll direction, and a control unit that controls the operation of each of the joints, the roll operation of the ankle joint in the left and right legs, and the movement of each joint in one leg. And a movement of the center of gravity of the robot in the left-right direction by a pitch operation.

Further, when moving the center of gravity of the robot in the left-right direction, the control section tilts the foot part in the direction opposite to the direction of movement of the center of gravity by the rolling motion of the ankle joints in the left and right legs, and It is preferable that the leg on the moving side of the center of gravity is contracted by the pitch motion of each joint on the leg on the moving side. In this case, the center of gravity can be kept lower than in the case where the center of gravity is moved by extending the other leg, so that the stability of the legged mobile robot during bipedal walking can be improved.

Further, the control unit is means for moving the center of gravity of the robot into one of the foot parts by the roll motion of the ankle joint part in the left and right leg parts and the pitch motion of each joint part in the one leg part. , A means for lifting the other leg by a pitch motion of each joint in the other leg, a means for stepping the other leg forward by a pitch motion of each joint in the other leg, and one leg Means for moving the center of gravity of the robot forward and landing the other leg part by the pitch motion of each joint part in each part, the roll motion of the ankle joint part in the left and right leg parts, and each joint part in one leg part And a means for moving the center of gravity of the robot between the left and right foot parts or into the other foot part. In this case, 1
While performing bipedal walking with four degrees of freedom per leg, it is possible to perform stable bipedal walking by always positioning the center of gravity of the robot during the one-leg supporting period within the foot portion of the supporting leg.

Further, in order to achieve the above object, a control method for a legged mobile robot according to the present invention is such that a pair of left and right leg portions provided on a robot body and a thigh portion of the leg portion are provided with respect to the robot body. A hip joint that operates in the pitch direction, a knee joint that operates the shin of the leg in the pitch direction with respect to the thigh, and a foot of the leg that pitches with respect to the shin. A method of controlling a legged mobile robot comprising an ankle joint part that is operated in a roll direction and a roll direction, and a control part that controls the operation of each joint part, and a roll operation of the ankle joint part in the left and right legs, By the pitch motion of each joint in one leg, the step of moving the center of gravity of the robot into one foot, and the pitch motion of each joint in the other leg lifts the other leg. The other The step of stepping the other leg forward by the pitch motion of each joint part of the robot part, and the pitch motion of each joint part of the one leg part move the robot center of gravity forward and land the other leg part A step of moving the robot center of gravity between the left and right foot parts or into the other foot part by a step, a roll operation of the ankle joint part in the left and right legs, and a pitch operation of each joint part in the one leg part; It is configured with.

A rotary shaft for performing three roll operations,
It is a legged mobile robot in which a plurality of bases (hip joints) of a foot for a robot having a rotary shaft for performing one pitch operation are connected.

Further, the rotating shaft for performing the roll operation is
An ankle joint portion, a knee joint portion, and a base portion of the foot,
In the legged mobile robot, the rotary shaft that performs the pitch motion is the ankle joint.

[0012]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a legged mobile robot, and FIG. 2 is a schematic perspective view showing the degree of freedom of the legged mobile robot. As shown in these figures, the legged mobile robot 10 includes a pair of left and right legs 12 on a robot body 11.
It is configured to include L and 12R. Each leg 12L, 12R
Are thighs 14L and 14R connected to the robot body 11 via hip joints 13L and 13R, and the thighs 14
Shins 16L and 16R connected to the lower ends of L and 14R via knee joints 15L and 15R, and shins 16L and 16R
The lower end portion of R has foot portions 18L and 18R connected to each other via ankle joint portions 17L and 17R. Hip joint 13
Hip joint pitch shafts 19 facing left and right are provided on L and 13R.
L and 19R are provided, and the hip joint pitch shaft 19 is provided.
The thighs 14L and 14R are moved in the pitch direction with respect to the robot body 11 with L and 19R as swing fulcrums. Further, knee joint portions 15L and 15R are provided with knee joint pitch shafts 20L and 20R that face in the left-right direction, and the knee joint pitch shafts 20L and 20R are used as rocking fulcrums for the shin portion 16.
L and 16R are operated in the pitch direction with respect to the thighs 14L and 14R. Further, the ankle joint portions 17L and 17R have ankle joint pitch axes 21L and 21R facing the left and right directions.
And ankle joint roll shafts 22L and 22R facing the front-rear direction, and these ankle joint pitch shafts 21L and
21R and the ankle joint roll shafts 22L and 22R are used as swing fulcrums, and the foot portions 18L and 18R are moved in the pitch direction and the roll direction with respect to the shin portions 16L and 16R. That is,
The legged mobile robot 10 of the present embodiment has four degrees of freedom per leg, and realizes bipedal locomotion by driving and controlling the four degrees of freedom while taking the robot center of gravity point P into consideration. It is a thing.

FIG. 3 is a block diagram showing the input / output of the control unit. As shown in this figure, the legged mobile robot 1
0 is a control unit 23 including a CPU, ROM, RAM and the like.
Is provided. On the input side of the control unit 23, hip joint pitch angle sensors 24L and 24R (for example, potentiometers) that detect the rotation angles of the hip joint pitch axes 19L and 19R, and knee joint pitch that detects the rotation angles of the knee joint pitch axes 20L and 20R. Angle sensors 25L and 25R and ankle joint pitch axis 2
Ankle joint pitch angle sensors 26L and 26R for detecting rotation angles of 1L and 21R, and ankle joint roll shafts 22L and 22R
Ankle joint roll angle sensor 27L that detects the rotation angle of the
7R is connected via a predetermined input circuit. On the other hand, on the output side of the control unit 23, hip joint pitch movement actuators 28L and 28R (for example, DC servomotors) for pitching the thighs 14L and 14R with respect to the robot body 11 and shins 16L and 16R are large. Thighs 14L, 14R
Knee joint pitch movement actuators 29L and 29R for making a pitch movement with respect to each other, ankle joint pitch movement actuators 30L and 30R for performing a pitch movement of the foot portions 18L and 18R with respect to the shin portions 16L and 16R, and the foot portion 18
Ankle joint roll operation actuators 31L, 31 for rolling the L, 18R with respect to the shins 16L, 16R
R is connected through a predetermined output circuit, and these actuators 28L to 31L and 28R to 31R are
Drive control is performed based on a biped walking program described in advance. The control procedure of bipedal walking in the legged mobile robot 10 will be described below with reference to FIGS. 4 to 12. However, in the following description, the pitch axes 19L to 21L and 19R to
The rotation directions CW and CCW of the rolls 21R are the rotation directions CW and CCW of the roll shafts 22L and 22R with the left side view as a reference viewpoint.
Uses the front view as the reference viewpoint. Also, the hip joint pitch axis 1
The rotational driving directions of 9L and 19R are the pitch movement directions of the thighs 14L and 14R with respect to the robot body 11, and the rotational driving directions of the knee joint pitch axes 20L and 20R are the thighs 14L.
The pitch movement directions of the shins 16L and 16R with respect to L and 14R and the rotational driving directions of the ankle joint pitch axes 21L and 21R are the foot flats 18L and 18R with respect to the shins 16L and 16R.
Of the foot part 1 relative to the shins 16L and 16R.
It is a roll operation direction of 8L and 18R.

FIG. 4 is a timing chart showing the operation timing of each pitch axis and roll axis. As shown in this figure, the legged mobile robot 10 realizes bipedal walking by performing seven motion steps (processes) as basic walking motions and alternately performing the basic walking motions left and right. The standing state and the seven operation steps (right leg stepping operation) will be sequentially described below.

FIG. 5A is a left side view of the legged mobile robot showing a standing state, FIG. 5B is a front view of the legged mobile robot, and FIG. 5C is a plan view of a foot portion. . As shown in these figures, in the standing state, the left and right legs 12 are
L, 12R joint parts 13L, 13R, 15L, 15
R, 17L, and 17R are kept symmetrical. At this time, the center of gravity P of the robot is located in the center between the left and right foot portions 18L and 18R.

FIG. 6A is a left side view of the legged mobile robot showing operation step 1 (movement of the center of gravity 1), and FIG.
[Fig. 3] is a front view of the legged mobile robot, and (C) is a plan view of a foot portion. As shown in these figures, in the operation step 1, the ankle joint roll shafts 22L and 22R of the left and right leg portions 12L and 12R are operated in the CCW direction. As a result, the legged mobile robot 10 stands up at the edges of the foot portions 18L and 18R with respect to the floor surface, but the robot center of gravity P is still located at the center between the left and right foot portions 18L and 18R.

FIG. 7A is a left side view of the legged mobile robot showing operation step 2 (movement of center of gravity 2), and FIG. 7B.
[Fig. 3] is a front view of the legged mobile robot, and (C) is a plan view of a foot portion. As shown in these drawings, in the operation step 1, the leg 12L on the side supporting the center of gravity (hereinafter,
It is called a supporting leg. ) The hip joint pitch axis 19L and the ankle joint pitch axis 21L are operated in the CW direction, and the knee joint pitch axis 20L is operated in the CCW direction, and the support leg 12L
Shrink. As a result, the legged mobile robot 10 is entirely tilted toward the support leg 12L, and the robot center of gravity P is set to the support leg 1L.
It moves into the 2L foot portion 18L. It should be noted that this operation step can be performed at the same time as the operation step 1 or before the operation step 1. Particularly, when the operation steps 1 and 2 are performed at the same time, it is possible to perform a continuous and smooth movement of the center of gravity.

FIG. 8A is a left side view of the legged mobile robot showing operation step 3 (movement of the stepped leg), FIG. 8B is a front view of the legged mobile robot, and FIG.
It is a top view of a foot part. As shown in these figures,
In operation step 3, the leg portion 12R on the stepping side
Hip joint pitch axis 19R (hereinafter referred to as the stepped-out leg)
And the ankle joint pitch axis 21R is operated in the CW direction, and the knee joint pitch axis 20R is operated in the CCW direction,
Shorten the foot 12R. At this time, since the robot center of gravity P is moving into the foot portion 18L of the support leg 12L, the stepping leg 12R is lifted along with the above operation.

FIG. 9A is a left side view of the legged mobile robot showing operation step 4 (stepping action of the stepped leg), FIG. 9B is a front view of the legged mobile robot, and FIG.
It is a top view of a foot part. As shown in these figures,
In operation step 4, the knee joint pitch shaft 20R of the stepping leg 12R is moved in the CW direction to move the stepping leg 1R.
2R is moved forward, and the ankle joint pitch axis 21R is moved in the CCW direction so that the foot portion 18R of the stepping leg 12R is kept parallel to the floor surface. By this operation, the center of gravity P of the robot moves to the front part of the foot portion 18L of the support leg 12L.

FIG. 10 (A) is a left side view of the legged mobile robot showing operation step 5 (stepping the foot on the floor), FIG. 10 (B) is a front view of the legged mobile robot, and FIG. ,
It is a top view of a foot part. As shown in these figures,
In operation step 5, the hip joint pitch shaft 19L of the support leg 12L is operated in the CCW direction, and the knee joint pitch shaft 20L and the ankle joint pitch shaft 21L are operated in the CW direction. By this motion (ankle joint pitch motion),
The center of gravity P of the robot moves further forward and is disengaged from the foot portion 18L of the support leg 12L. At this time, the legged mobile robot 10 falls forward and the stepping leg 12R is landed.
At this time, the robot body 11 and the foot portion 1 are moved by the hip joint pitch motion and the knee joint pitch motion of the support legs 12L.
8L is kept in parallel.

FIG. 11A is a left side view of the legged mobile robot showing operation step 6 (upright motion 1), and FIG. 11B.
[Fig. 3] is a front view of the legged mobile robot, and (C) is a plan view of a foot portion. As shown in these figures, in the operation step 6, the hip joint pitch shaft 19L of the support leg 12L is
And the ankle joint pitch axis 21L is operated in the CCW direction, and the knee joint pitch axis 20L is operated in the CW direction,
The support leg 12L is extended. By this operation, the center of gravity P of the robot moves between the left and right foot portions 18L and 18R, and accordingly, the legged mobile robot 10 moves the foot portion 18 to the floor surface.
It rises at the edges of L and 18R.

FIG. 12A is a left side view of the legged mobile robot showing operation step 7 (upright motion 2), and FIG.
[Fig. 3] is a front view of the legged mobile robot, and (C) is a plan view of a foot portion. As shown in these figures, in the operation step 7, the ankle joint roll shafts 22L and 22R of the left and right leg portions 12L and 12R are operated in the CW direction. By this operation, the left and right foot portions 18L and 18R become parallel to the floor surface, and the legged mobile robot 10 stands upright (upright). At this time, the center of gravity P of the robot is the left and right foot portions 18L,
It is located in the center of the polygon formed by 8R and maintains a stable state. Note that this operation step can be performed at the same time as the operation step 6 or before the operation step 6. In particular, when the operation steps 6 and 7 are performed at the same time, it is possible to perform a continuous and smooth erecting operation.

As described above, according to the present embodiment, the legged mobile robot 10 includes the pair of left and right legs 12L and 12R provided on the robot body 11 and the thighs 14L and 14R of the legs 12L and 12R. , Hip joints 13L and 13R that move in the pitch direction with respect to the robot body 11,
Knee joints 15L and 15R for moving the shins 16L and 16R of the legs 12L and 12R in the pitch direction with respect to the thighs 14L and 14R, and foot portions 18L and 18R of the legs 12L and 12R. Is provided with ankle joints 17L and 17R for operating the shins 16L and 16R in the pitch direction and the roll direction, and a controller 23 for controlling the operation of each joint, and the controller 23 controls the left and right sides. Legs 12L,
Roll motion of the ankle joints 17L and 17R in 12R and each joint 13 in one leg 12L (12R)
L, 15L, and 17L (13R, 15R, and 17R pitch movements move the robot center of gravity point P in the left-right direction. As a result, bipedal walking for alternately lifting the left and right legs 12L and 12R is performed per leg. This is possible with four degrees of freedom, and as a result, the processing load on the control unit 23 is reduced and real-time control is possible, and the cumulative error in the joints can be reduced to improve the operation accuracy. .

When the robot center of gravity point P is moved in the left-right direction, the control section 23 controls the left and right legs 12L, 1L.
By the rolling motion of the ankle joints 17L and 17R in 2R, the foot portions 18L and 18R are tilted in the direction opposite to the direction of movement of the center of gravity, and the leg 12L (12R) on the side of movement of the center of gravity.
Each joint 13L, 15L, 17L (13R, 1
5R, 17R), the leg portion 12L (12R) on the side of moving the center of gravity is contracted by the pitch movement of the other leg portion 12R.
The center of gravity can be kept low and the stability of the legged mobile robot 10 during bipedal walking can be increased as compared with the case where the center of gravity is moved by the stretching operation of (12L).

Further, the control unit 23 includes the left and right legs 12
The robot center of gravity P is determined by the roll motion of the ankle joints 17L and 17R in L and 12R and the pitch motion of the joints 13L, 15L and 17L (13R, 15R and 17R) in the one leg 12L (12R). Operation steps 1 and 2 for moving into one foot 18L (18R)
And each joint 13 in the other leg 12R (12L)
R, 15R, 17R (13L, 15L, 17L) pitch operation, the operation step 3 of lifting the other leg 12R (12L), and the joints 13R, 15R, 17R (in the other leg 12R (12L). 13L, 15
L, 17L) pitch action of the other leg 12R
Step 12 of stepping forward on (12L), and the joints 13L and 15 of one leg 12L (12R)
By the pitch motion of L, 17L (13R, 15R, 17R), the robot center of gravity point P is moved forward and the other leg 12R (12L) is landed on the operation step 5 and the left and right legs 12L, 12R. Ankle joint 17L, 17
R roll action and each joint part 13L, 15L, 17L (13R, 15R,
17R) to move the center of gravity P of the robot between the left and right foot portions 18L and 18R (or within the other foot portion) according to the pitch operation 17R).
While performing bipedal walking with four degrees of freedom per leg, the robot center of gravity P in the one-leg supporting period is always positioned in the foot portion 18L (18R) of the supporting leg 12L (12R), and stable 2 Can walk on foot.

Although one embodiment of the present invention has been described above with reference to the drawings, the present invention is not limited to the matters shown in the above embodiment, and the claims and the detailed description of the invention, and It includes a range in which those skilled in the art can make changes and applications based on well-known techniques.

[0027]

As described above, according to the present invention, bipedal walking in which the left and right legs are alternately lifted is made possible with four degrees of freedom per leg, and as a result, the processing load on the control unit is reduced. In addition to enabling real-time control, it is possible to reduce cumulative errors in joints and improve operation accuracy.

[Brief description of drawings]

FIG. 1 is a perspective view of a legged mobile robot.

FIG. 2 is a schematic perspective view showing degrees of freedom of a legged mobile robot.

FIG. 3 is a block diagram showing input / output of a control unit.

FIG. 4 is a timing chart showing the operation timing of each pitch axis and roll axis.

5A is a left side view of the legged mobile robot showing a standing state, FIG. 5B is a front view of the legged mobile robot,
(C) is a plan view of the foot portion.

FIG. 6A is an operation step 1 (movement of center of gravity 1).
3B is a left side view of the legged mobile robot, FIG. 4B is a front view of the legged mobile robot, and FIG.

FIG. 7A is an operation step 2 (movement of center of gravity 2).
3B is a left side view of the legged mobile robot, FIG. 4B is a front view of the legged mobile robot, and FIG.

FIG. 8 (A) is a left side view of the legged mobile robot showing operation step 3 (stepping leg lifting operation);
[Fig. 3] is a front view of the legged mobile robot, and (C) is a plan view of a foot portion.

FIG. 9A is a left side view of the legged mobile robot showing operation step 4 (stepping operation of the stepping leg); FIG.
[Fig. 3] is a front view of the legged mobile robot, and (C) is a plan view of a foot portion.

FIG. 10 (A) is a left side view of the legged mobile robot showing operation step 5 (landing operation of the stepping leg);
[Fig. 3] is a front view of the legged mobile robot, and (C) is a plan view of a foot portion.

11A is a left side view of the legged mobile robot showing operation step 6 (upright movement 1), FIG. 11B is a front view of the legged mobile robot, and FIG. FIG.

12A is a left side view of the legged mobile robot showing operation step 7 (upright movement 2), FIG. 12B is a front view of the legged mobile robot, and FIG. FIG.

[Explanation of symbols]

P robot center of gravity 10-legged mobile robot 11 Robot body 12L, 12R legs 13L, 13R hip joint 14L, 14R thigh 15L, 15R knee joint 16L, 16R shin 17L, 17R Ankle joint 18L, 18R foot part 19L, 19R Hip pitch axis 20L, 20R Knee joint pitch axis 21L, 21R Ankle joint pitch axis 22L, 22R Ankle joint roll axis 23 Control unit

Claims (6)

[Claims] 1. A pair of left and right legs provided on a robot main body, a hip joint for moving a thigh of the leg in a pitch direction with respect to the robot main body, and a shin of the leg. A knee joint part that moves in the pitch direction with respect to the thigh, an ankle joint part that moves the foot part of the leg in the pitch direction and the roll direction with respect to the shin, and motions of the joint parts A control unit that controls the robot center of gravity in the left-right direction by a roll motion of the ankle joint part in the left and right legs and a pitch motion of each joint part in the one leg. A legged mobile robot characterized by. 2. The control unit, when moving the center of gravity of the robot in the left-right direction, tilts the foot portion in the direction opposite to the direction of movement of the center of gravity by rolling action of the ankle joints in the left and right legs, and The legged mobile robot according to claim 1, wherein the leg on the center of gravity moving side is contracted by the pitch motion of each joint in the leg on the moving side. 3. The means for moving the center of gravity of the robot into one foot by means of a roll motion of the ankle joint part in the left and right legs and a pitch motion of each joint part in the one leg. , A means for lifting the other leg by a pitch motion of each joint in the other leg, a means for stepping the other leg forward by a pitch motion of each joint in the other leg, and one leg Means for moving the center of gravity of the robot forward and landing the other leg part by the pitch motion of each joint part in the knee part, the roll motion of the ankle joint part in the left and right leg parts, and each joint part in one leg part And a means for moving the center of gravity of the robot between the left and right foot parts or into the other foot part by the pitch movement of.
The legged mobile robot described in. 4. A pair of left and right legs provided on the robot body, a hip joint that moves the thighs of the legs in the pitch direction with respect to the robot body, and a shin of the legs. A knee joint part that moves in the pitch direction with respect to the thigh, an ankle joint part that moves the foot part of the leg in the pitch direction and the roll direction with respect to the shin, and motions of the joint parts A control method for a legged mobile robot comprising: a control unit that controls the robot center of gravity by a roll motion of an ankle joint part on the left and right legs and a pitch motion of each joint part on one leg. The step of moving into one foot, the step of lifting the other leg by the pitch motion of each joint in the other leg, and the step of pitching each joint in the other leg, the other leg Step forward And the step of moving the center of gravity of the robot forward by the pitch motion of each joint in one leg, and landing the other leg, and the rolling motion of the ankle joint in the left and right legs. A step of moving the center of gravity of the robot between the left and right foot parts or into the other foot part by the pitch motion of each joint part of the leg part. 5. A legged mobile robot formed by connecting a plurality of bases (hip joints) of a robot for a robot having a rotary shaft that performs three roll motions and a rotary shaft that performs one pitch motion. 6. A rotary shaft for performing the roll motion is an ankle joint, a knee joint, and a base of the foot, and a rotary shaft for performing the pitch motion is the ankle joint. The legged mobile robot according to claim 5.