JP4770990B2 - Legged mobile robot and control method thereof - Google Patents

Description

  The present invention relates to a realistic robot mechanism configured by modeling biological mechanisms and operations, and more particularly to a legged mobile robot that models the body mechanisms of legged mobile animals such as humans and monkeys. Regarding the mechanism.

  More specifically, the present invention relates to a legged mobile robot of a type in which each of two or more movable legs realizes an operation pattern such as walking, running, jumping, etc. by cooperatively repeating landing and leaving actions. Leg movement type that can reduce the impact received from the floor as much as possible when landing after the robot leaves the floor, especially when executing jumps and other movement patterns The present invention relates to a robot mechanism and its control method.

  It is said that the word “robot” comes from the Slavic word ROBOTA (slave machine). In Japan, robots started to spread from the end of the 1960s, but many of them are industrial robots such as manipulators and transfer robots for the purpose of automating and unmanned production operations in factories. Met.

  Recently, research and development on legged mobile robots simulating the body mechanisms and movements of biped upright walking such as humans and monkeys has progressed, and expectations for practical use are also increasing. Leg-type movement with two legs standing upright is unstable and difficult to control posture and walking, compared to crawler type, four-legged or six-legged type, etc. It is excellent in that it can realize traveling motion.

  For example, among legged walking robots, a joint structure applied to a structure corresponding to a lower body is proposed (for example, see Patent Document 1).

  A legged mobile robot that emulates a human biological mechanism or movement is particularly called a “humanoid” or “humanoid robot”. The humanoid robot can provide, for example, life support, that is, support for human activities in various situations in daily life such as a living environment.

  The significance of researching and developing robots called humanoids or humanoids can be understood from, for example, the following two viewpoints.

  One is a human scientific viewpoint. In other words, through the process of creating a robot with a structure resembling human lower limbs and / or upper limbs, devising its control method and simulating human walking motion, the mechanism of human natural motion including walking Can be elucidated in engineering. Such research results can be greatly reduced to the progress of various other research fields dealing with human movement mechanisms, such as ergonomics, rehabilitation engineering, or sports science.

  The other is the development of a robot that supports life as a human partner, that is, supports human activities in various situations in the living environment and other daily lives. This kind of robot needs to learn how to adapt to a person or an environment with different personalities while learning from humans in various aspects of the human living environment, and needs to grow further in terms of functionality. At this time, it is considered that the robot having the “human shape”, that is, the same shape or the same structure as the human, functions effectively for smooth communication between the human and the robot.

  For example, when teaching a robot on the ground how to get through a room while avoiding obstacles that should not be stepped on, rather than having a completely different structure than the one you are teaching, such as a crawler or quadruped robot, A biped walking robot having the same appearance will be much easier to teach, and will be easier for the robot to teach (see, for example, Non-Patent Document 1). In the first place, since most of the human living environment is formed according to the form and behavior of human beings, having a humanoid form increases the affinity with the human living environment. It can be said that it is essential above.

  One of the uses of the humanoid robot is to perform various difficult operations in industrial activities and production activities. For example, maintenance work at nuclear power plants, thermal power plants, petrochemical plants, transportation and assembly work of parts at manufacturing plants, cleaning of high-rise buildings, substitution of dangerous work and difficult work such as rescue at fire sites etc. . However, robots specializing in this type of industrial use have the ultimate design and production theme of realizing specific uses or functions, and are supposed to be biped, but humans and monkeys stand upright. It is not always necessary to faithfully reproduce the body mechanisms and movements inherent to walking animals as mechanical devices. For example, while strengthening the degree of freedom and movement functions of the hand to realize a specific application, it limits the degree of freedom of the head, trunk (such as the spine), and the waist, which are relatively unrelated to the application. It should be allowed to some extent to omit it. As a result, biped walking and so-called edo may remain unnatural for humans in terms of the appearance of robot work and operations, but this point must be compromised.

  Further, as another use of the humanoid robot, there is a use that is close to life, that is, “symbiosis” with a human, rather than life support such as substitution of difficult work. This type of robot is designed to faithfully reproduce the whole body cooperative movement mechanism inherent in animals that walk on two legs upright, such as humans and monkeys, and to achieve its natural and smooth movement. To do. In addition, as long as it emulates highly intelligent upright animals such as humans and monkeys, it is desirable that the expression of movement using the extremities is rich. Furthermore, not only to faithfully execute the pre-input motion pattern, but also to realize a lively motion expression that responds to the opponent's language and attitude (such as “praise”, “speak”, “beat”). Is also required. In this sense, an entertainment robot that imitates humans is just right to call it a “humanoid robot”.

  As already known, the human body has hundreds of joints, or hundreds of degrees of freedom. It is preferable to give almost the same degree of freedom in order to give the movement to the legged mobile robot as close as possible to a human, but this is extremely difficult technically. This is because it is necessary to arrange at least one actuator for each degree of freedom. However, mounting several hundred actuators on a mechanical device called a robot is difficult in terms of manufacturing cost. This is impossible from the design point of view. In addition, if the degree of freedom is large, the amount of calculation for the position / motion pattern control, posture stability control, and the like of the robot increases exponentially.

  For this reason, it is common to construct a humanoid robot with joint degrees of freedom of about several tens, which is much smaller than the human body. Therefore, it can be said that one of the important issues in the design and control of humanoid robots is how to realize more natural movements with less freedom.

  For example, it is already clear from the viewpoint of ergonomics that a flexible mechanism such as the spine is important for performing various and complex operations in the human life. The degree of freedom of trunk joints, which means the spine, has low value for industrial applications, but is important for entertainment and other life-oriented humanoid robots. Moreover, it is required that the flexibility can be actively adjusted according to the situation.

  In addition, legged mobile robots that perform biped upright walking are superior in that they can realize flexible walking and running operations (for example, raising and lowering stairs and getting over obstacles), but the center of gravity is higher, so Posture control and stable walking control become difficult by the amount. In particular, in the case of robots that are closely linked to daily life, postures and stable walking must be controlled while richly expressing natural movements and emotions in intelligent animals such as humans and monkeys.

  Numerous techniques related to posture control and stable walking have been proposed for robots of the type that perform legged movement by biped walking. Stable “walking” in this context can be defined as moving with legs without falling down.

  At the time of walking, gravity, inertial force, and these moments act on the road surface from the walking system due to gravity and acceleration caused by walking motion. According to the so-called “Dalambert principle”, they balance with the floor reaction force and the floor reaction force moment as a reaction from the road surface to the walking system. As a result of the dynamic reasoning, there is a point where the pitch and roll axis moment become zero on the side of the support polygon formed by the sole contact point and the road surface, or “ZMP (Zero Moment Point)”.

  Many of the proposals regarding the stable walking of the robot use this ZMP as a standard for determining the stability of walking. The biped walking pattern generation based on the ZMP norm has advantages such that a foot landing point can be set in advance and it is easy to consider the kinematic constraint conditions of the foot according to the road surface shape.

  For example, a walking control device for a legged mobile robot has been proposed (see, for example, Patent Document 2). The walking control device described in the publication controls ZMP, that is, a point on the floor where the moment caused by the floor reaction force when walking is zero to coincide with the target value.

  In addition, there is a proposal for a legged mobile robot in which the ZMP is located inside the support polyhedron (polygon) or at a position having at least a predetermined margin from the end of the support polyhedron (polygon) when landing or leaving the floor. (For example, see Patent Document 3). As a result, even if a disturbance or the like is received, there is a ZMP margin for a predetermined distance, and the stability of walking can be improved.

  In addition, a proposal has been made for controlling the walking speed of a legged mobile robot according to a ZMP target position (see, for example, Patent Document 4). That is, the legged mobile robot described in the publication uses the walking pattern data set in advance, drives the leg joint so that the ZMP matches the target position, detects the inclination of the upper body, The discharge speed of the walking pattern data set according to the detected value is changed. As a result, when the robot leans forward, for example, by stepping on unexpected irregularities, the posture can be recovered by increasing the discharge speed. In addition, since the ZMP can be controlled to the target position, there is no problem even if the discharge speed is changed during the both-leg support period.

  Further, a proposal has been made for controlling the landing position of a legged mobile robot according to a ZMP target position (see, for example, Patent Document 5). That is, the legged mobile robot described in the publication detects a deviation between the ZMP target position and the actually measured position and drives one or both of the legs so as to eliminate it, or around the ZMP target position. A stable walking is performed by detecting the moment and driving the leg so that it becomes zero.

  In addition, a proposal has been made for controlling the tilt posture of a legged mobile robot according to a ZMP target position (see, for example, Patent Document 6). In other words, the legged mobile robot described in the publication detects a moment around the ZMP target position, and when a moment is generated, drives the leg so that the moment becomes zero, so that a stable walking is performed. It has become.

  Unlike stationary robots such as manipulators and crawl-type mobile robots, legged mobile robots realize walking motions as a whole robot by repeatedly repeating the landing and getting-off motions of multiple movable legs. To do. At the time of landing, a reaction force from the floor surface is applied as an impact to the movable legs and the entire robot. Naturally, repeated impacts and corner impacts cause fatigue and breakage of joints (actuators) and other parts.

  In addition, human legged movement is not limited to walking movement, and further includes movement with a relatively long bed leaving period such as running and jumping. Although all of the above-described conventional technologies related to humanoid robots are only proposals for walking motions, the realization of motion patterns including the robot's bed leaving period, such as running and jumping, is typical of human beings in nature or naturally. This is one of the operation patterns. Needless to say, the movement pattern of jumping or dropping from a high place is included in the design goals of legged or humanoid robots.

  For example, in the case of the above-described humanoid robot for entertainment, a highly entertaining work such as dancing or playing games such as sports is performed. Therefore, in addition to the movement patterns that occur during human work, such as walking and stair climbing, the frequency of executing movement patterns with a long bed leaving period, such as running, jumping, jumping off high places, etc., is extremely high. is expected. In addition, a long bed leaving period means falling from a higher position. Since the robot itself is a heavy object, a much larger impact is applied when it falls than when the movable leg during normal walking is subjected to landing.

  It can be said that entertainment-oriented humanoid robots are more frequently impacted by landing. For this reason, the joint actuator is easily damaged or broken, and other parts are easily damaged.

  For example, in a situation where a legged mobile robot is likely to fall, control of the legged mobile robot that can reduce damage to the robot due to the fall and damage to the object on the other side that the robot collides with when it falls Proposals have been made for devices (see, for example, Patent Document 7).

  However, this proposed control device can reduce damage to the robot body or the case, but does not attempt to reduce the impact applied to the joint actuator.

  In addition, this proposed control device simply controls to lower the center of gravity of the robot when landing due to falling, and mitigates the impact received from the floor surface through the entire period from leaving the floor to landing. There is no mention of such points. In the first place, it considers only when the legged mobile robot falls, and is irrelevant to an operation pattern with a relatively long bed leaving period, such as a jump operation or a fall from a high place.

  In addition, the proposed control device controls to lower the center of gravity of the robot when landing due to falling, but the posture of the robot after landing is only assumed to be in a falling state. In other words, it is unrelated to the technical problem of stably controlling the posture of the robot so that it does not fall when it leaves the floor by a jumping operation and then landes again.

Japanese Patent Laid-Open No. 3-184782 JP-A-5-305579 JP-A-5-305581 JP-A-5-305583 JP-A-5-305585 JP-A-5-305586 JP-A-11-481705

Takanishi, “Control of biped robots” (Japan Society for Automotive Engineers Kanto Branch <Koyo> No. 25, 1996 APRIL)

  The present invention has been made in view of the technical problems as described above, and the object thereof is to walk, run, jump by each of two or more movable legs executing a landing and a leaving operation in a coordinated manner repeatedly. It is an object of the present invention to provide an excellent control mechanism for a legged mobile robot that realizes an operation pattern such as the above.

  It is a further object of the present invention to provide an excellent control mechanism for a legged mobile robot capable of mitigating as much as possible the impact received from the floor surface when landing after the robot has left the floor. It is to provide.

  It is a further object of the present invention to provide a legged mobile robot capable of mitigating as much as possible the impact that the joint actuator receives from the floor surface when landing after the robot has jumped or performed other actions. It is to provide an excellent control mechanism.

  A further object of the present invention is to reduce the impact received from the floor surface as much as possible by performing a series of operations throughout the period from the robot jumping or performing other leaving operations to the landing. It is to provide an excellent control mechanism for a legged mobile robot.

  A further object of the present invention is to provide a legged mobile robot that can stably control the posture so that the robot does not fall over when landing after the robot has jumped or performed other floor movements. It is to provide an excellent control mechanism.

The present invention has been made in consideration of the above-mentioned problems, and the first side surface thereof is composed of at least a lower limb and an upper body disposed above the lower limb, and performs various operations according to the movement of the lower limb. A legged mobile robot that realizes a pattern,
A joint actuator with variable impedance provided at least on the lower limbs;
Detecting means for detecting whether the robot is leaving or landing; and
The impedance of the joint actuator is reduced in response to detecting that it is during the bed leaving period, and the impedance of the joint actuator is returned to the original value before the landing operation in response to detecting the landing. Control means for performing predetermined control, etc.
It is a legged mobile robot characterized by comprising.

  According to the legged mobile robot according to the first aspect of the present invention, the robot lowers the impedance of its joint actuator during the bed leaving period so that the joint actuator itself functions as a cushioning material. Can wait.

  Further, at the time of landing, the buffering effect can be ensured by restoring the impedance of the joint actuator to the original state over a predetermined time.

  In addition, after the impedance of the joint actuator is restored and the normal control state is restored, the posture control is performed so that the ZMP of the robot 100 enters the stable region based on the stability determination standard by the ZMP, so that the robot after landing Can avoid a secondary dangerous situation in which a person falls.

Further, the second aspect of the present invention is a legged mobile robot composed of at least a lower limb and an upper body disposed above the lower limb, and realizing various operation patterns by movement of the lower limb,
Detecting means for detecting whether the robot is leaving or landing; and
First driving means for extending and bending the lower limbs;
Second driving means for extending and bending the upper body;
Control means for controlling the driving of the first and second driving means,
The control means includes
In response to detecting that it is during a bed leaving period, the first and second are such that the upper body extends in a direction opposite to the direction of gravity and / or the lower limb extends in the direction of gravity. And controlling each of the driving means of
In response to detecting the landing, each of the first and second driving means is controlled so that the position of the center of gravity of the entire robot is lowered.
This is a legged mobile robot.

  According to the legged mobile robot according to the second aspect of the present invention, during the bed leaving period, the robot takes a posture that extends in the vertical direction (described later: see FIG. 8), and the center of gravity position is landed. Wait for landing in a position that is as high as possible from the sole of the foot. Furthermore, the maximum impact force received from the floor surface at the time of landing can be reduced by taking an operation pattern in which the position of the center of gravity gradually decreases within a predetermined acceleration range when landing.

  In addition, when landing, by performing posture control so that the ZMP of the legged mobile robot enters the stable region, it is possible to avoid a secondary dangerous situation in which the robot falls over after landing. it can.

  Here, in response to detecting the landing, the control means controls each of the first and second driving means so that the position of the center of gravity of the entire robot falls within an allowable acceleration. Also good.

  In addition, the control means determines whether the ZMP of the robot is in the stable region at the time of landing, and if the determination result is negative, the control unit is configured so that the ZMP enters the stable region. You may make it perform the process which changes the attitude | position of a robot.

The third aspect of the present invention is a legged mobile robot that is composed of at least a lower limb and an upper body disposed above the lower limb, and realizes various operation patterns by movement of the lower limb,
Detecting means for detecting whether the robot is leaving or landing; and
First driving means for driving each joint of the lower limbs;
Second driving means for driving each joint of the upper body;
Control means for controlling the driving of the first and second driving means,
The control means includes
In response to detecting that it is during the bed leaving period, it is determined whether or not the virtual ZMP on the virtual floor plane is within the virtual stable region,
In response to the negative determination result, each of the first and second driving means is controlled so that the virtual ZMP falls within the virtual stable region.
This is a legged mobile robot.

  According to the legged mobile robot according to the third aspect of the present invention, the robot can stand by until it leaves the floor while maintaining a stable posture with respect to the virtual floor plane during the bed leaving period. As a result, it is possible to eliminate as much as possible the possibility that the robot loses balance at the time of landing and the robot falls, and that part or all of the robot is damaged by the fall.

  The control means reduces the impedance of the joint actuator in response to detecting that it is during the bed leaving period, and returns the impedance of the joint actuator to the original value in response to detecting the landing. Thus, an impact absorbing operation at the time of landing may be performed. Alternatively, the control means may perform an impact absorbing operation at the time of landing so that the position of the center of gravity of the entire robot is lowered within an allowable acceleration in response to the detection of the landing by the robot.

According to a fourth aspect of the present invention, there is provided a control method for a legged mobile robot comprising at least a lower limb and an upper body disposed above the lower limb, and realizing various motion patterns by movement of the lower limb. And at least the joint actuator provided in the lower limb is variable in impedance,
(A) reducing the impedance of the joint actuator during a bed leaving period;
(B) performing predetermined control such as returning the impedance of the joint actuator to the original value at the time of landing;
A control method for a legged mobile robot.

  In the control method according to the fourth aspect of the present invention, in step (b), the impedance may be continuously returned toward the original value continuously for a predetermined time.

A control method according to the fourth aspect of the present invention is as follows.
(C) upon landing, determining whether the ZMP of the robot is within a stable region;
(D) If the determination result in step (c) is negative, changing the posture of the robot so that ZMP falls within the stable region;
May be further provided.

The fifth aspect of the present invention is a legged mobile robot control method comprising at least a lower limb and an upper body disposed above the lower limb, and realizing various motion patterns by movement of the lower limb. The legged mobile robot includes first driving means for extending and bending the lower limbs, and second driving means for extending and bending the upper body,
(A) During the bed leaving period, each of the first and second driving means is controlled so that the upper body extends in a direction opposite to the direction of gravity and / or the lower limbs extend in the direction of gravity. And steps to
(B) controlling each of the first and second driving means so that the position of the center of gravity of the entire robot is lowered in response to detecting the landing;
This is a control method for a legged mobile robot.

  In the control method according to the fifth aspect of the present invention, in the step (b), each of the first and second drive means is controlled so that the position of the center of gravity of the entire robot falls within an allowable acceleration. May be.

A control method according to the fifth aspect of the present invention is
(C) upon landing, determining whether the ZMP of the robot is within a stable region;
(D) If the determination result in step (c) is negative, changing the posture of the robot so that ZMP falls within the stable region;
May be further provided.

The sixth aspect of the present invention is a legged mobile robot control method comprising at least a lower limb and an upper body disposed above the lower limb, and realizing various motion patterns by movement of the lower limb. There,
(A) determining whether the legged mobile robot is in a bed leaving period;
(B) detecting the direction of gravity of the legged mobile robot;
(C) setting a virtual floor plane of the legged mobile robot;
(D) setting a virtual stable region of the legged mobile robot;
(E) calculating a virtual ZMP of the legged mobile robot;
(F) determining whether the virtual ZMP is within a virtual stable region;
(G) in response to the determination result in the step (f) being negative, changing the posture of the legged mobile robot so that the virtual ZMP falls within the virtual stable region;
A control method for a legged mobile robot.

  The control method according to the sixth aspect of the present invention includes a step of reducing the impedance of the joint actuator in response to detecting that it is during a bed leaving period, and a step of reducing the impedance of the joint actuator in response to detecting landing. The step of returning the impedance to the original value may be further included.

  In addition, in response to detecting the landing, the robot may further include a step of controlling the posture so that the position of the center of gravity of the entire robot falls within an allowable acceleration.

  According to the present invention, it is possible to provide an excellent legged mobile robot and a method for controlling the same that can alleviate as much as possible the impact received from the floor surface when landing after the robot has left the floor after jumping. Can do.

  Further, according to the present invention, an excellent legged mobile robot capable of reducing as much as possible the impact that the joint actuator receives from the floor surface when landing after the robot has jumped or performed other flooring operations, and The control method can be provided.

  In addition, according to the present invention, the impact received from the floor surface can be reduced as much as possible through a series of operations through the entire period until the robot reaches the floor after jumping or performing other bed leaving operations. An excellent legged mobile robot and its control method can be provided.

  In addition, according to the present invention, when the robot is landing after jumping or performing other bed leaving operations, it is possible to stably control the posture of the robot so that the robot does not fall down. The control method can be provided.

  Other objects, features, and advantages of the present invention will become apparent from more detailed description based on embodiments of the present invention described later and the accompanying drawings.

It is the figure which showed a mode that the humanoid robot 100 used for implementation of this invention was looked at from the front. It is the figure which showed a mode that the humanoid robot 100 used for implementation of this invention was looked at from back. It is the figure which showed typically the degree-of-freedom composition model which humanoid robot 100 concerning this example has. It is the figure which showed typically the control system structure of the humanoid robot 100 which concerns on a present Example. It is the flowchart which showed an example of the process sequence at the time of the robot 100 landing. 2 is a block diagram showing a servo circuit and a control system related to one actuator used in the robot 100. FIG. It is the flowchart which showed the other example regarding the process sequence at the time of the robot 100 landing. FIG. 3 is a diagram illustrating a state in which the robot 100 during the bed leaving phase has both hands and both legs extended and the posture (the height) from the tip of the foot that reaches the floor to the center of gravity of the entire robot 100 is as long as possible. It is the figure which showed the specific example of the attitude | position which the robot 100 takes at the time of landing. It is the chart which showed the impact force which robot 100 receives from a floor surface at the time of landing. Is a chart showing the relationship between the impact force received from the speed and the floor to move the center of gravity of the robot 100 from point G ₀ to point G _F during implantation. It is the flowchart which showed the other example regarding the process sequence at the time of the robot 100 landing. 3 illustrates a virtual floor plane for the robot 100 when leaving the bed. 3 illustrates a virtual stable region of the robot 100 when getting out of bed. It is the figure which showed typically an example of the joint model structure about a humanoid robot. It is the figure which showed typically the other example of the joint model structure about a humanoid robot.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 and FIG. 2 show a state in which the humanoid or humanoid robot 100 used for carrying out the present invention is viewed from the front and the rear. Further, FIG. 3 schematically shows the joint degree-of-freedom configuration of the humanoid robot 100.

  As shown in FIG. 3, the humanoid robot 100 connects an upper body including two arms and a head 1, a lower limb composed of two legs that realize a moving operation, and an upper limb and a lower limb. Consists of the trunk.

  The neck joint that supports the head 1 has three degrees of freedom: a neck joint yaw axis 2, a neck joint pitch axis 3, and a neck joint roll axis 4.

  Each arm portion includes a shoulder joint pitch axis 8, a shoulder joint roll axis 9, an upper arm yaw axis 10, an elbow joint pitch axis 11, a forearm yaw axis 12, a wrist joint pitch axis 13, and a wrist joint roll. It comprises a shaft 14 and a hand portion 15. The hand portion 15 is actually a multi-joint / multi-degree-of-freedom structure including a plurality of fingers. However, since the movement of the hand portion 15 has little contribution or influence to the posture stability control or the walking movement control of the robot 100, it is assumed in this specification that there is zero degree of freedom. Therefore, it is assumed that each arm portion has seven degrees of freedom.

  The trunk has three degrees of freedom: a trunk pitch axis 5, a trunk roll axis 6, and a trunk yaw axis 7.

  In addition, each leg constituting the lower limb includes a hip joint yaw axis 16, a hip joint pitch axis 17, a hip joint roll axis 18, a knee joint pitch axis 19, an ankle joint pitch axis 20, and a joint roll axis 21. It is comprised with the foot | leg part (plant sole) 22. Assume that the intersection point of the hip joint pitch axis 17 and the hip joint roll axis 18 defines the hip joint position of the robot 100 according to the present embodiment. The human foot (sole) 22 is actually a structure including a multi-joint / multi-degree-of-freedom sole, but the sole of the humanoid robot 100 according to the present embodiment has zero degrees of freedom. . Accordingly, each leg is configured with 6 degrees of freedom.

  In summary, the entire humanoid robot 100 according to the present embodiment has a total of 3 + 7 × 2 + 3 + 6 × 2 = 32 degrees of freedom. However, the humanoid robot 100 for entertainment is not necessarily limited to 32 degrees of freedom. It goes without saying that the degree of freedom, that is, the number of joints, can be increased or decreased as appropriate in accordance with design and manufacturing constraints and required specifications.

  Each degree of freedom of the humanoid robot 100 as described above is actually implemented using an actuator. It is preferable that the actuator be small and light in light of demands such as eliminating the appearance of extra bulges on the appearance and approximating the shape of a human body, and performing posture control on an unstable structure such as biped walking. . In this embodiment, a small AC servo actuator of a gear direct connection type and a servo control system of a single chip built in a motor unit is mounted. This type of AC servo actuator is disclosed in, for example, Japanese Patent Application No. 11-33386, which has already been assigned to the present applicant.

  FIG. 4 schematically shows a control system configuration of the humanoid robot 100. As shown in the figure, the humanoid robot 100 performs adaptive control for realizing cooperative operation between each mechanism unit 30, 40, 50R / L, 60R / L and each mechanism unit representing human limbs. It is comprised with the control unit 80 to perform (however, each of R and L is a suffix which shows each of right and left, and so on).

  The entire operation of the humanoid robot 100 is controlled by the control unit 80 in an integrated manner. The control unit 80 includes data and commands for the main control unit 81 composed of main circuit components (not shown) such as a CPU (Central Processing Unit) chip and a memory chip, and each component of the power supply device and the robot 100. It comprises a peripheral circuit 82 including an interface (not shown) for performing transmission and reception.

  In this embodiment, the power supply apparatus has a configuration (not shown in FIG. 4) including a battery for driving the robot 100 autonomously. If it is a self-supporting drive type, the physical action radius of the humanoid robot 100 can be freely walked without being restricted by the power cable. Further, during various exercises including walking and other upper limbs, it is not necessary to consider interference with the power cable, and operation control is facilitated.

Each degree of freedom of joint in the robot 100 shown in FIG. 3 is realized by a corresponding actuator. That is, the head unit 30 includes a neck joint yaw axis actuator A ₂ , neck joint pitch axis actuator A ₃ , neck joint roll representing the neck joint yaw axis 2, neck joint pitch axis 3, and neck joint roll axis 4. A shaft actuator A ₄ is provided.

The trunk unit 40 includes a trunk pitch axis actuator A ₅ , a trunk roll axis actuator A ₆ representing the trunk pitch axis 5, the trunk roll axis 6, and the trunk yaw axis 7. A shaft actuator A ₇ is respectively provided.

Further, the arm unit 50R / L is subdivided into an upper arm unit 51R / L, an elbow joint unit 52R / L, and a forearm unit 53R / L, but the shoulder joint pitch axis 8, the shoulder joint roll axis 9, and the upper arm Shoulder joint pitch axis actuator A ₈ representing shoulder joint pitch axis 11, elbow joint roll axis 12, wrist joint pitch axis 13, wrist joint roll axis 14, shoulder joint roll axis actuator A ₉ , upper arm yaw An axis actuator A ₁₀ , an elbow joint pitch axis actuator A ₁₁ , an elbow joint roll axis actuator A ₁₂ , a wrist joint pitch axis actuator A ₁₃ , and a wrist joint roll axis actuator A ₁₄ are provided.

The leg unit 60R / L is subdivided into a thigh unit 61R / L, a knee unit 62R / L, and a shin unit 63R / L, but the hip joint yaw axis 16, the hip joint pitch axis 17, the hip joint Hip joint yaw axis actuator A ₁₆ , hip joint pitch axis actuator A ₁₇ , hip joint roll axis actuator A ₁₈ , knee joint pitch representing the roll axis 18, knee joint pitch axis 19, ankle joint pitch axis 20, and ankle joint roll axis 21. An axis actuator A ₁₉ , an ankle joint pitch axis actuator A ₂₀ , and an ankle joint roll axis actuator A ₂₁ are provided.

Each of the actuators A ₂ , A ₃ ... Is more preferably a small AC servo actuator (described above) of a gear direct connection type and a servo control system that is mounted on a motor unit in a single chip.

  For each mechanism unit such as the head unit 30, the trunk unit 40, the arm unit 50, and each leg unit 60, sub-control units 35, 45, 55, and 65 for actuator drive control are respectively provided. Furthermore, grounding confirmation sensors 91 and 92 for detecting whether or not the soles of the leg portions 60R and 60L have landed are mounted, and a posture sensor 93 for measuring posture is provided in the trunk unit 40. ing. In this embodiment, an acceleration sensor is used as the attitude sensor 93. The control targets can be dynamically corrected by detecting the landing and leaving periods of the sole 22, the inclination of the trunk portion, and the like based on the outputs of the sensors 91 to 93.

  The main control unit 80 performs adaptive control on each of the sub-control units 35, 45, 55, and 65 in response to the outputs of the sensors 91 to 93, and the upper limbs, the trunk, and the humanoid robot 100. The coordinated movement of the lower limbs can be realized. The main control unit 81 sets a foot movement, a ZMP trajectory, a trunk movement, an upper limb movement, a waist height, and the like according to a user command and the like, and commands for instructing an operation according to these setting contents. Transfer to the controller 35, 45, 55, 65.

Then, in each of the sub-control section 35, 45 ... interprets the command received from the main control unit 81 outputs a drive control signal to the actuators A _2, A ₃ .... Here, “ZMP” refers to a point on the floor where the moment due to floor reaction force during walking is zero, and “ZMP trajectory” refers to, for example, during the walking operation period of the robot 100. It means the trajectory that ZMP moves.

  Next, a processing procedure when the humanoid robot 100 is dropped and landed after a bed leaving period such as a jump will be described.

  FIG. 5 illustrates an example of a processing procedure during landing in the form of a flowchart. Hereinafter, each step of this flowchart will be described.

  When the robot 100 performs a bed leaving operation (step S11), the ground contact confirmation sensors 91 and 92 provided on the soles of both feet are turned off (step S12), and the main control unit 81 detects the bed leaving state. . The movement pattern of the leaving action here is not particularly specified, such as a jumping action or an action of jumping off from a high place, and therefore the description thereof is omitted in this specification.

  In response to detecting the bed leaving motion, the control parameter value of each joint actuator is changed (step S13). More specifically, the control parameter is changed so that the impedance of the actuator is lowered. Since the actuator with low impedance is in a flexible state, it functions as a buffer when landing and can absorb the impact received from the floor surface. In particular, it is preferable to change the impedance of an actuator that receives a large impact near the floor, such as an ankle joint or a knee joint.

  FIG. 6 shows a block diagram of a servo circuit related to one actuator used in the robot 100 and its control system 200. As shown in the figure, the control system is a type of control system that receives position command and speed command and feeds back position detection. The position command is input to the position controller 201, the output of the position controller 201 and the speed command are input to the speed controllers 202 and 203, the output of the speed controller 203 is supplied to the actuator 204, and the actuator 204 is driven. . In addition, a position detection signal from an encoder (not shown) attached to the actuator 204 is fed back to the position controller 201, and a time differentiated signal is fed back to the speed controller 202.

Each of K _pp , K _vi , and K _vp shown in FIG. 6 is a control parameter for this servo control system. By changing at least one of these parameters to a small value, the impedance of the actuator 200 decreases.

  The actuator 200 is a small AC servo actuator of the type directly connected to the gear and having a servo control system integrated into a motor unit. For example, Japanese Patent Application No. 11-29 already assigned to the present applicant. No. 33386.

  Returning to FIG. 5 again, the processing procedure will be described. In step S14, both the ground sensors 91 and 92 of both feet are turned on (or one of the sensors is turned on), and the robot 100 is on standby until it reaches the floor surface.

  When landing of the robot 100 is detected, the control parameter value of the joint actuator changed in step S13 is returned to the original value (step S15). As a result, the impedance of the actuator is recovered, and a state before leaving the bed where the operation of the robot 100 can be controlled is obtained. However, if the impedance is sharply recovered, the effect as a buffer material is lost, and therefore, it returns to the original value over a predetermined time T (for example, about several hundred milliseconds).

  Next, it is determined whether or not the ZMP of the robot 100 is in a stable region, for example, at the planted sole (step S16). If ZMP is not in the stable region, the posture of the entire robot 100 is changed so as to enter the stable region (step S17).

  On the other hand, if the ZMP is in the stable region, the entire processing procedure is terminated.

  According to the landing processing procedure as shown in FIG. 5, the robot 100 may reduce the impedance of its joint actuator during the bed leaving period, and wait for the robot 100 to land while the actuator functions as a cushioning material. it can.

  Further, when the robot 100 is landed, the buffering effect can be ensured by restoring the impedance to the original state after a predetermined time.

  In addition, after the robot 100 has landed and the impedance of the joint actuator has recovered and returned to the normal control state, the posture control is performed so that the ZMP of the robot 100 enters the stable region based on the stability determination criterion by the ZMP. By doing so, it is possible to avoid a secondary dangerous situation in which the robot 100 falls over after landing.

  FIG. 7 illustrates another example in the form of a flowchart regarding a processing procedure at the time of landing. Hereinafter, each step of this flowchart will be described.

  When the robot 100 performs a bed leaving operation (step S21), the ground contact confirmation sensors 91 and 92 provided on the soles of both feet are turned off (step S22), and the main controller 81 determines whether the robot 100 has left the floor. Detected. As for the leaving action here, an action pattern such as a jumping action or an action of jumping down from a high place is not particularly specified, and thus description thereof is omitted in this specification.

  In response to detecting the bed leaving motion, the pitch axis at each joint of the upper limb and trunk of the robot 100 is rotationally driven in the direction opposite to the direction of gravity, and the lower limbs and legs are extended in the direction of gravity (step S23). ).

  FIG. 8 schematically illustrates an example of a posture in which the pitch axis at each joint of the upper limb and trunk of the robot 100 is rotationally driven in the direction opposite to the direction of gravity and the lower limbs and legs are extended in the direction of gravity. ing. As shown in the figure, the posture of the robot 100 is controlled so that both hands and both feet of the robot 100 extend. As a result, the distance (height) h from the tip of the foot to the center of gravity G of the entire robot 100 is longer than the center of gravity G ′ before extending the limb.

  In step S24, both the ground sensors 91 and 92 of both feet are turned on (or one of the sensors is turned on) and waits until the robot 100 reaches the floor surface.

  When the landing of the robot 100 is detected, the pitch axes of the upper limb, the lower limb, and the trunk joint of the robot are driven so that the center of gravity of the robot 100 is lowered (step S25).

  An example of a posture in which the center of gravity of the robot 100 is lowered is a state in which both legs, hip joints, and trunk joints are bent and bent as shown in FIG. 9, for example. It will be understood that the distance from the foot that has landed to the center of gravity is sufficiently short.

By the bending operation in step S25, the center of gravity of the robot 100 moves from the landing time G ₀ to the landing operation end time (when stable) G _F (where G ₀ > G _F ). By spending a predetermined time T for this series of landing operations, the impact force that the robot 100 receives from the floor surface is gently dispersed during the time T as shown in the chart of FIG. 10, and the maximum impact force is also reduced. The

  However, the bending operation in step S25 needs to be controlled with emphasis on the driving speed of each joint axis so that the value of the acceleration sensor 93 does not exceed the allowable acceleration value (that is, the posture is bent). This is because if the bending motion is performed at a value exceeding the allowable acceleration, the impact applied to the robot 100 is rather amplified.

Figure 11 shows the relationship between the impact force received from the speed and the floor to move the center of gravity of the robot 100 from point G ₀ to point G _F during landing on the chart. More specifically, T respectively T ₁ (time required from i.e. implantation up to the stabilization) required time gravity center position moves from point G ₀ to point G _F, T _2, and T ₃ (where, T _{The case where 1} <T ₂ <T ₃ ) is plotted. As can be seen from the figure, the shorter the required time, the faster the acceleration of movement of the center of gravity position, and the maximum value of the impact force F received from the floor surface increases in proportion to this. Conversely, the longer the time required for the movement of the center of gravity, the lower the acceleration, the impact upon landing is absorbed by the movement of the center of gravity, and the maximum value of the impact force F is reduced.

  Next, it is determined whether or not the ZMP of the robot 100 is in a stable region, for example, at the planted sole (step S26). If ZMP is not in the stable region, the posture of the entire robot 100 is changed so as to enter the stable region (step S27).

  On the other hand, if the ZMP is in the stable region, the entire processing procedure is terminated.

  According to the landing processing procedure as shown in FIG. 7, the robot 100 takes a posture in which the robot 100 extends in the vertical direction during the bed leaving period (see FIG. 8), and the center of gravity position is as much as possible from the sole where the floor is landing. It is possible to wait for landing in a high position. Furthermore, the maximum impact force received from the floor surface can be reduced by taking an operation pattern in which the position of the center of gravity gradually decreases within a predetermined acceleration range during landing.

  Further, when landing, by performing posture control so that the ZMP of the robot 100 enters the stable region, it is possible to avoid a secondary dangerous situation in which the robot 100 falls over after landing. .

  FIG. 12 illustrates another example of the processing procedure at the time of landing in the form of a flowchart. Hereinafter, each step of this flowchart will be described.

  When the robot 100 performs a bed leaving operation (step S31), the ground contact confirmation sensors 91 and 92 provided on the soles of both feet are turned off (step S32), and the main control unit 81 detects the bed leaving state. . As for the leaving action here, an action pattern such as a jumping action or an action of jumping down from a high place is not particularly specified, and thus description thereof is omitted in this specification.

  In response to detecting the bed leaving motion, the main control unit 81 calculates the direction of gravity based on the output of the attitude sensor 93 (step S33), and sets the virtual floor plane (step S34). In the present specification, the “virtual floor plane” refers to a plane assumed to have landed in the current posture of the robot 100. A plane whose normal vector is the gravity vector at the lowest point of the robot 100 (either a left or right foot or both feet in a normal leaving operation such as a jump) corresponds to a virtual floor plane (see FIG. 13).

  Next, a virtual stable area on the virtual floor plane is set (step S35). In this specification, the “virtual stable region” refers to a region on the floor where the robot 100 can maintain stability when it is landed on the virtual floor plane in the current posture of the robot 100. . For example, it corresponds to both feet that have landed on a virtual floor plane (see FIG. 14).

  Next, a virtual ZMP is calculated (step S36). The “virtual ZMP” is a point on the virtual floor plane where the moment due to the floor reaction force on the virtual floor plane is zero.

  In decision block S37, it is determined whether or not the virtual ZMP is within the virtual stable region.

  If the determination result is negative, the posture of the robot 100 is changed by driving at least some joint actuators of the upper limb, lower limb, and trunk of the robot 100 so that the virtual ZMP falls within the virtual stable region ( Step S38).

  As a result of the posture control as described above, the robot 100 can wait for the landing while always maintaining a stable posture with respect to the virtual floor plane during the bed leaving period. At the time of landing, the virtual floor plane coincides with the actual floor plane, but in step S39 described above, the robot 100 can land in a stable posture. The landing operation may include an impact absorbing operation as described with reference to FIGS.

  In short, if the posture control processing procedure as shown in FIG. 12 is followed, the robot 100 can stand by until it leaves the floor while maintaining a stable posture with respect to the virtual floor plane during the bed leaving period. As a result, it is possible to eliminate as much as possible the possibility that the robot 100 will fall out of balance at the time of landing, and that part or all of the robot 100 will be damaged by the fall. Furthermore, a perfect landing operation can be realized by incorporating the above-described shock absorbing operation.

  The present invention has been described in detail above with reference to specific embodiments. However, it is obvious that those skilled in the art can make modifications and substitutions of the embodiments without departing from the gist of the present invention.

  In the present specification, the present invention has been described by taking a humanoid robot that performs legged movement with two legs as an example, but the gist of the present invention is not limited to a biped robot. For example, the present invention can be suitably applied to a quadruped walking robot such as a pet-type robot that models a dog or other legged mobile robots having a lower number of legs. Further, as shown in the present embodiment, the present invention can be applied to a robot of a type in which an upper limb or a head is not mounted on the trunk (trunk unit).

  In short, the present invention has been disclosed in the form of exemplification, and should not be interpreted in a limited manner. In order to determine the gist of the present invention, the claims section described at the beginning should be considered.

  In determining the gist of the present invention, it is not appropriate to strictly apply FIG. 3 for the names of joints and the like for the biped robot 100. It should be interpreted flexibly by contrast with the animal's physical mechanism.

  For reference, the joint model configuration of a humanoid robot is illustrated in FIG. In the example shown in the figure, a portion including the shoulder joint 5 to the upper arm, the elbow joint 6, the forearm, the wrist 7 and the hand portion 8 is referred to as an “upper limb”. The range from the shoulder joint 5 to the hip joint 11 is called a “trunk” and corresponds to the human torso. In addition, a range from the hip joint 11 to the trunk joint 10 among the trunk is referred to as a “lumbar region”. The trunk joint 10 has an effect of expressing the degree of freedom of the human spine. Further, a portion including the thigh 12, the knee joint 14, the crus 13, the ankle 15, and the foot 16 below the hip joint 11 is referred to as “lower limb”. Generally, the upper part of the hip joint is called the “upper body” and the lower part is called the “lower body”.

  FIG. 16 illustrates another joint model configuration of a humanoid robot. The example shown in the figure is different from the example shown in FIG. 14 in that the trunk joint 10 is not provided. Refer to the figure for the names of each part. As a result of the omission of the trunk joint corresponding to the spine, the upper body movement of the humanoid robot loses its expressive power. However, in the case of a humanoid robot for industrial purposes such as dangerous work or substitution of work, there is a case where movement of the upper body is not required. It should be understood that the reference numerals used in FIGS. 15 and 16 do not match those in other drawings such as FIG.

DESCRIPTION OF SYMBOLS 1 ... Head, 2 ... Neck joint yaw axis 3 ... Neck joint pitch axis, 4 ... Neck joint roll axis 5 ... Trunk pitch axis, 6 ... Trunk roll axis 7 ... Trunk yaw axis, 8 ... Shoulder joint pitch axis DESCRIPTION OF SYMBOLS 9 ... Shoulder joint roll axis, 10 ... Upper arm yaw axis 11 ... Elbow joint pitch axis, 12 ... Forearm yaw axis 13 ... Wrist joint pitch axis, 14 ... Wrist joint roll axis 15 ... Hand part, 16 ... Hip joint yaw axis 17 ... Hip joint Pitch axis, 18 ... Hip joint roll axis 19 ... Knee joint pitch axis, 20 ... Ankle joint pitch axis 21 ... Ankle joint roll axis, 22 ... Foot (plant sole)
DESCRIPTION OF SYMBOLS 30 ... Head unit, 40 ... Trunk unit 50 ... Arm unit, 51 ... Upper arm unit 52 ... Elbow joint unit, 53 ... Forearm unit 60 ... Leg unit, 61 ... Thigh unit 62 ... Knee joint unit, 63 ... Tibial unit 80 ... Control unit 81 ... Main control unit 82 ... Peripheral circuit 91,92 ... Earth contact confirmation sensor 93 ... Attitude sensor 100 ... Humanoid robot

Claims (14)

A legged mobile robot having at least a lower limb,
A joint actuator provided at least on the lower limb;
Detecting means for detecting whether the robot is leaving or landing; and
In response to detecting that the detection means is in the period of getting out of bed, the impedance of the joint actuator is lowered, and in response to detection of landing by the detection means, a predetermined impedance is set to the impedance of the joint actuator. Control means for controlling;
A legged mobile robot comprising:   2. The legged mobile robot according to claim 1, wherein the control means returns the impedance of the joint actuator to the original value in response to the detection means detecting the landing.   The said control means returns the impedance of the said joint actuator continuously toward the original value continuously for a predetermined time in response to the said detection means detecting landing. The legged mobile robot according to 1.   The control means, after returning the impedance of the joint actuator to the original value, determines whether or not the ZMP of the robot is within the stable region, and if the determination result is negative, the ZMP is The legged mobile robot according to claim 1, wherein a process of changing a posture of the robot so as to fall within a stable region is executed. A legged mobile robot having an upper body and a lower limb connected to the upper body,
Detecting means for detecting whether the robot is leaving or landing; and
First driving means for extending and bending the lower limbs;
Second driving means for extending and bending the upper body;
Control means for controlling the driving of the first and second driving means,
The control means includes
In response to detecting that the detecting means is in the period of getting out of bed, the first and second are so that the upper body extends in a direction opposite to the direction of gravity and the lower limb extends in the direction of gravity. And controlling each of the driving means of
In response to the detection means detecting landing, each of the first and second driving means is controlled so that the center of gravity of the entire robot is lowered.
This is a legged mobile robot. In response to the detection of the landing by the detection means, the control means controls each of the first and second drive means so that the position of the center of gravity of the entire robot falls within an allowable acceleration. The legged mobile robot according to claim 5 , wherein: The control means determines whether or not the ZMP of the robot is in the stable region after lowering the center of gravity of the entire robot, and if the determination result is negative, the ZMP is in the stable region. The legged mobile robot according to claim 5 , wherein a process of changing the posture of the robot so as to enter is executed. A method for controlling a legged mobile robot having at least a lower limb, wherein at least a joint actuator provided in the lower limb is variable in impedance
(A) reducing the impedance of the joint actuator during a bed leaving period;
(B) performing predetermined control on the impedance of the joint actuator when landing;
A control method for a legged mobile robot, comprising:   9. The control method for a legged mobile robot according to claim 8, wherein, in the step (b), the impedance of the joint actuator is returned to an original value in response to detection of landing.   9. The step (b) according to claim 8, wherein the impedance of the joint actuator is continuously returned toward the original value for a predetermined time in response to the detection of the landing. The control method of the legged mobile robot as described. further,
(C) determining whether the ZMP of the robot is within a stable region after returning the impedance of the joint actuator to an original value;
(D) If the determination result in step (c) is negative, changing the posture of the robot so that ZMP falls within the stable region;
The method for controlling a legged mobile robot according to claim 8, comprising: A control method of a legged mobile robot having an upper body and a lower limb connected to the upper body, wherein the legged mobile robot extends a first driving means for extending and bending the lower limb, and extending the upper body And second driving means for bending,
(A) controlling each of the first and second driving means so that the upper body extends in a direction opposite to the gravitational direction and the lower limb extends in the gravitational direction during a bed leaving period;
(B) controlling each of the first and second driving means so that the position of the center of gravity of the entire robot is lowered in response to detecting the landing;
A control method for a legged mobile robot, comprising:   13. The legged mobile robot according to claim 12, wherein in the step (b), each of the first and second driving means is controlled so that the center of gravity of the entire robot is lowered within an allowable acceleration. Control method. further,
(C) determining whether the ZMP of the robot is within a stable region after lowering the center of gravity of the entire robot;
(D) If the determination result in step (c) is negative, changing the posture of the robot so that ZMP falls within the stable region;
The method for controlling a legged mobile robot according to claim 12, comprising:

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