JP2001310278A - Quadruped walking robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light quadruped walking robot to be operated by a small energy consumption and capable of stably walking on an irregular ground with a degree of freedom as small as possible. SOLUTION: This quadruped walking robot is formed of a body 1 having a revolute pair γ of active joints and a pair of leg parts connected to both ends of the body through direct acting pairs αand β of active joints. A rotary pair of driving system of a fore and aft directional axis is provided at a central part of the body so as to select idle legs and adjust the height of the idle legs with the operation for twisting a front part and a rear part of the body. Two front legs and two rear legs are formed into a pair for unifying, and each central part is connected to the body with the passive revolute pair of the vertical shaft. This connection part is connected to the body for drive with the translation pair in the fore and aft direction so as to realize the movement of the idle leg in the fore and aft direction and the movement of the center of gravity in the fore and aft direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a four-legged walking robot that walks on four feet, and more particularly to a four-legged walking robot that can walk with four feet and maintain static stability with four feet.

[0002]

2. Description of the Related Art Conventionally, a robot that walks on four legs has been realized, and usually has three degrees of freedom (three driving systems) for one leg in order to exhibit a sufficient function. The function to move the leg to the position is realized. If one foot has three degrees of freedom, a total of twelve drive systems are required. For this reason, the conventional four-legged walking robot has many drive systems, and the drive systems are complicated and expensive, and the weight of the machine increases. As the weight increases, higher output actuators are required,
It is easy to fall into a vicious circle of additional weight. In addition, since the actuator keeps outputting force even in a stationary state, it consumes much energy.

[0003]

As described above, the conventional 4
A walking robot has many drive systems, the weight of the machine becomes heavy, and a high-output actuator is required.
Since the actuator keeps outputting torque even in a stationary state, there is a disadvantage that energy consumption is increased. In other words, the multi-degree of freedom means the improvement of the moving work performance, but it increases the weight, complicates the control, and the like. For this reason, the appearance of a four-legged walking robot that can stably walk on uneven terrain with a small degree of freedom is desired.

[0004] As a multi-legged walking machine proposed for this purpose, a journal of the Robotics Society of Japan, Vol. 2, No. 2
(April, 1984), "Basic Considerations on the Degree of Freedom of Multi-legged Walking Machines" (Kaneko, Abe, Tate). In this document, classifications of degrees of freedom are shown, and it is shown that the sum of active degrees of freedom and degrees of freedom of mechanisms can be important indicators when considering the degrees of freedom of walking machines. I have. And as minimum functions required for a multi-legged walking machine on the premise of static stability, (1) the ability to maintain static stability, (2) the ability to reach an arbitrary position on uneven terrain, 3) It is shown that the body can be held horizontally on uneven terrain and the absolute height of the body can be kept as constant as possible. It has been shown that six active degrees of freedom are necessary and sufficient requirements to realize these functions.

As described above, there are walking machines with reduced degrees of freedom in the past, but still have six degrees of freedom, and further simplification and weight reduction are required. Further, the technique disclosed in the above-mentioned literature does not have a structure in which the energy consumption is small in a stationary state.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a four-legged walking robot that can walk stably on uneven terrain with as little freedom as possible, and that is lightweight and consumes little energy. Is to provide.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a quadruped walking robot, and an object of the present invention is to provide a torso having a rotating pair of active joints and a linearly moving pair of active joints at both ends of the body. This is achieved by providing a pair of legs connected together.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Considering the functions of a quadruped walking robot from the standpoint of walking, it is important to be able to select an arbitrary scaffold and reach an arbitrary position while maintaining static stability on uneven terrain. At this time, it is not necessary to keep the body horizontal. For this purpose, any one leg can be used as a free leg, and it is necessary and sufficient that the free leg has three degrees of freedom.

The walking motion of a four-legged walking robot has a total of 12 degrees of freedom with one leg having three degrees of freedom when focusing on the movement of each leg. Looking at the movements later, the only movements that are moving up and down the free leg, moving the free leg forward, and moving the torso forward. Although the swing leg switches on the way, the degree of freedom to work simultaneously is always 3 or less. From this, it is considered that the quadrupedal walking with three degrees of freedom can be realized by properly positioning the active joint (actuator). 3 for swing movement
The degree of freedom and the movement of the center of gravity require a total of four degrees of freedom, one degree of freedom. Even if the movement of the free leg is two degrees of freedom, it is possible to move forward and backward, curve and turn. Sidewalking is not possible because the left and right movement of the swing leg is involved. Therefore, three degrees of freedom can be used, and four degrees of freedom are better. Also,
Since the support leg is restrained by contact with the ground, it is not necessary to restrain the drive leg by three degrees of freedom, so that a passive joint can be introduced.

[0010] The rotation system of the front-rear direction shaft is installed in the center of the body, and the play legs can be selected and the height of the play legs can be adjusted by twisting the front and rear parts of the body. Also, before 2
The leg and the rear two legs are combined in pairs, and the center of each is connected to the fuselage by a passive rotating pair of vertical axes. The connecting portion is connected to and driven by the translational pair in the front-rear direction with respect to the body, thereby realizing the front-rear movement of the free leg and the front-rear movement of the center of gravity. A robot satisfying such conditions is shown in FIG.

In the robot of FIG. 1 according to the present invention, in order to reduce the degree of freedom of the quadruped walking robot, instead of driving each leg as in the prior art, twisting of the long body 1 and the two ends of the body 1 The front legs 2 and the rear legs 3 provided are driven in a total of three degrees of freedom in the forward and backward movements. The torso 1 is twisted by a rotating pair of active joints (actuators) γ provided substantially at the center of the torso 1, and the front leg 2 and the rear leg 3
Is performed by linearly-coupled active joints (actuators) α and β provided at both ends of the body 1. With these three degrees of freedom, static walking of an arbitrary stride including a turning on an uneven ground is realized. Specifically, the center of gravity is moved back and forth by the actuators α and β, and the free leg is moved back and forth, and the actuator γ is used to change the height of the free leg and stably ground the support leg on uneven ground.

FIG. 2 shows a state in which the state of the three-degree-of-freedom robot according to the present invention is divided into a position of the center of gravity projection point and a ground contact state of the legs. The position of the center of gravity projection point is divided by a support leg diagonal line. Are divided into four ranges A, B, C, and D. As a result, the state of the robot is shown in FIG. 2 with two legs in contact with all four legs (FIGS. 2 (B) and 2 (D)) and with one free leg (FIGS. 2 (A), (C) and (D), (F)), which can be divided into a total of six states, that is, four states. The positions where the centroid projection points fall in the sections B and D are not used. In FIG. 2, marks indicate free legs that are not grounded, and black circles indicate support legs that are grounded.

Here, the projection of the center of gravity from section A to section C can be realized by simultaneously moving the active joints (actuators) α and β in opposite directions. In addition, the state A in FIG.
0, when the active joint (actuator) γ is driven in the positive direction, the fourth leg becomes the free leg, the state A in FIG.
4. In the state A, the third leg becomes a free leg when driven in the negative direction.
3 can be transferred. Further, in the state D0 in FIG. 2B in which all the legs touch the ground and the center of gravity projection point is in the section D, when the active joint (actuator) γ is driven, the first leg and the second leg 2A and the state D1 of FIG.
The state can be shifted to the state D2 of (C). State D1 in FIG.
In, the free legs are active joints (actuators) α, β,
It has three degrees of freedom by driving γ. Considering symmetry, the free leg also has three degrees of freedom in states D2, A3, and A4. Table 1 shows the relationship between the active joints (actuators) α, β, γ and the movement of the swing legs in the reference posture.

[0014]

[Table 1] FIG. 3 shows the appearance of the present invention, and Table 2 shows the specifications of the robot.

[0015]

[Table 2] The active joints α and β are constituted by a linear motion mechanism using a ball screw, and the active joint γ is driven via a harmonic gear.

The actual design of the robot has the structure shown in FIGS. That is, a body rotating part (active joint γ) 10 is provided at the center of the body 1, legs 11 and 12 are provided at both ends of the body 1, and both ends of the legs 11 and 12 are provided. , The walking feet 13 and 14 are hung. The legs 11 and 12 are connected to the upper part of the body 1 via passive joints (active joints α and β) 15 and 16, respectively, and are moved by linear motion actuators 17 and 18 in the left and right directions shown in the figure. ing. The torso rotating part (active joint γ) 10 is rotated by a rotation actuator 19.

The above example is a three-degree-of-freedom quadruped walking robot, but FIG. 6 shows a four-degree-of-freedom robot with legs extendable. In the example shown in FIG. 6, an active joint δ driven by differential rotation is provided on the leg, and the leg can freely expand and contract.

FIG. 7 shows a detailed mechanism of the active joint δ. The actuator 30 drives the differential mechanism 31 and drives the bevel gear mechanisms 32 and 33 by the differential operation.
Screws 34 and 35 are screwed into the bevel gear mechanisms 32 and 33, respectively, and nuts 36A and 36B and 37A and 37B are screwed into the screws 34 and 35, respectively. The screws of the screws 34 and 35 are engraved in opposite directions toward both ends with respect to the center. The nuts 36A, 36B and 37A, 37B are respectively connected to end portions of leg portions, and the nuts 36A, 36B are rotated by rotating the screw 34 via the bevel gear mechanism 32.
B opens or closes, and by rotating the screw 35 through the bevel gear mechanism 33, the nuts 37A and 37B open or close. Nuts 36A, 36B and 37A,
Since 37B is connected to both ends of the leg, the distance between the feet and the distance between the feet shown in FIG. 6 can be differentially controlled.

[0019]

As described above, according to the quadruped walking robot of the present invention, the robot is configured with a small number of degrees of freedom (three or four degrees of freedom), thereby realizing a reduction in weight and a control mechanism. Is also simplified. Moreover, the degree of freedom is reduced as much as possible while maintaining a stable walking function, and the weight is reduced. In addition, a structure in which energy consumption at rest is small is achieved, and the power source mounted on the vehicle can be reduced in weight.

[Brief description of the drawings]

FIG. 1 is a schematic structural view of a three-degree-of-freedom robot according to the present invention.

FIG. 2 is a center-of-gravity projection view showing an operation example of the robot according to the present invention.

FIG. 3 is an external view of a robot according to the present invention.

FIG. 4 is a plan structural view of an actual robot.

FIG. 5 is a sectional view taken along line AA in FIG.

FIG. 6 is a schematic structural view of a four-degree-of-freedom robot according to the present invention.

FIG. 7 is a mechanism diagram showing an example of a leg extension / contraction mechanism.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Torso 2 Front leg part 3 Hind leg part alpha, beta Active joint (actuator) of direct-acting pair even rotation γ Active joint (actuator) of pair rotation 10 Torso rotating part (active joint γ) 11, 12 Leg 13, 14 Foot 30 Actuator 31 Differential mechanism

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Fumitoshi Ito 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term (reference) 3F060 AA00 CA14 CA26 GA05 GA13 GB11 GB19 GB25 GB28 GD13 HA02

Claims (4)

[Claims] 1. A body having a rotating pair of active joints, and a pair of legs connected to both ends of the body via direct-moving pair of active joints, respectively. Quadruped walking robot. 2. The four-legged walking robot according to claim 1, wherein said pair of legs has a structure in which legs are suspended via arms. 3. The four-legged walking robot according to claim 2, wherein said arm portion is configured to expand and contract. 4. The four-legged walking robot according to claim 3, wherein the expansion and contraction of the arm is performed by a differential mechanism.