JP2005177918A - Robot device and compliance device for robot device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize impact absorption and dynamic operation in performing sudden operation such as running or jumping. <P>SOLUTION: A movable leg of a robot is composed of a linear motion mechanism of one degree of freedom combining a mixed control system comprising an active servo control system and a passive mechanism control system. A mechanism system passive and capable of responding in a wide band is arranged in series between a driving system based on active control comprising a servo motor, and an output part (an effector such as a joint). The passive mechanism system is composed of preload, friction and other nonlinear elements in addition to compliance elements such as a spring and a damper. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a robot apparatus that includes a plurality of movable legs and performs legged work, and more particularly, to a robot apparatus that autonomously performs abrupt operations such as running and jumping.

  More particularly, the present invention relates to a robot apparatus that realizes shock absorption and dynamic operation when performing abrupt operations such as running and jumping, and a compliance device for the robot apparatus.

  A mechanical device that uses an electrical or magnetic action to perform a movement resembling human movement is called a “robot”. 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 has progressed, and expectations for practical use have also increased. A legged mobile robot modeled on human movement is particularly called a “humanoid” or “humanoid robot”.

  Leg type movement with two legs standing up is unstable and difficult to control posture and walking, compared to crawler type, four or six legs type, etc., but walking with irregularities on the work path such as rough terrain and obstacles It is excellent in that it can realize flexible movement work, such as being able to cope with discontinuous walking surfaces such as up and down of surfaces and stairs and ladders.

  Many techniques relating to posture control and stable walking related to a biped legged mobile robot have already been proposed. Stable “walking” as used herein is defined as “moving with legs without falling down”. The overturning of the airframe means that the robot is interrupting the work being executed, and considerable effort and time are spent to get up from the overturned state and resume the work. In addition, there is a risk that the robot body itself or the object on the other side colliding with the falling robot may be fatally damaged by the fall. For this reason, posture stability control for avoiding falls is positioned as one of the most important issues in the development of legged mobile robots.

  In a robot that performs upright walking, the normal upright posture as a basic posture is unstable in the first place. In many cases, ZMP (Zero Moment Point) is used as a norm for determining the stability of walking for posture stability control of a legged mobile robot. The standard for discriminating the stability by ZMP is the principle of D'Alembert that gravity and inertia force from the walking system to the road surface, and these moments balance with the floor reaction force and the floor reaction force moment as a reaction from the road surface to the walking system. based on. As a result of mechanical reasoning, there is a point where the pitch axis and roll axis moments become zero, that is, ZMP (for example, non-MPM) inside the support polygon (that is, the ZMP stable region) formed by the plantar contact point and the road surface. (See Patent Document 1).

  In the case of a biped robot, the robot is generally performed by repeating a walking cycle divided into the following operation periods.

(1) Single leg support period with left leg lifted right leg (2) Both leg support period with right leg grounded (3) Single leg support period with right leg lifted with left leg (4) Both legs with left leg grounded Support period

  As described above, since the legged mobile robot repeatedly performs discrete ground contact movements with the environment, it is extremely important to reduce the impact at the time of ground contact in order to stabilize the behavior of the robot. As long as your feet are in contact with the road surface, you will always receive reaction force from the road surface. For this reason, the stability and controllability at the time of the legged work in the legged mobile robot is affected not only by the movement pattern of the limbs but also by the state of the road surface (ground, floor surface) where the legged work such as walking is performed.

  Here, the degree of freedom of the movable part of the robot is generally realized by driving and controlling the rotation angle and angular velocity of the motor / actuator corresponding to the joint axis by a servo control system. The servo control system is superior in that the characteristics can be clearly determined and controlled, and thus has many advantages such as ensuring stability and ensuring safety in terms of operation.

  Conventional robot walking technology has been centered on relatively stable walking, and even if it is called “dynamic walking” from the viewpoint of control engineering, its motion is visually gentle. It ’s far from running around. In such operations, drive control by servo control is well suited and can provide high performance to the aircraft.

  On the other hand, it has been impossible until now to make a robot run at high speed. This is because it is difficult to obtain sufficient speed and acceleration with a normal motor / actuator, and it is not suitable for abrupt operations such as so-called flying and jumping.

  Conventionally, as a robot capable of jumping, for example, “3D One Leg Hopper” can be cited (for example, see Non-Patent Document 2). This type of robot is equipped with a pneumatic direct acting cylinder on a leg and supports it with a gimbal mechanism to transmit force in an arbitrary direction. The gimbal angle is variable on the roll axis and the pitch axis. Due to the characteristics of the pneumatic cylinder, it can be moved with a relatively large force and at a high speed, and Hopping, that is, jumping can be realized.

  However, in order to drive the pneumatic cylinder, a power source such as a compressor having sufficient capacity is required. It is not realistic to mount such a power source in a robot body that searches for a free path.

  Further, when the robot apparatus travels or jumps, it is particularly important to reduce the impact at the time of ground contact.

  For example, a biped walking robot has been proposed in which a foot is filled with a soft member to achieve shock absorption / relaxation at landing and stabilization of posture after landing (see, for example, Patent Document 1). . However, this is not a robot that runs or jumps.

  Considering the realization of rapid movements such as running and jumping of robot devices using a motor / servo system, the vicious cycle of using an extremely large motor and securing the power source necessary to drive the motor is repeated. It will be. This is because the speed and acceleration capabilities of the motor are limited, and it is difficult to perform jumping or running with the capability of the motor alone.

JP 2001-129774 A "Migir Vokobratovic" "LEGGED LOCATION ROBOTS" (Ichiro Kato's "Walking Robot and Artificial Feet" (Nikkan Kogyo Shimbun)) Two authors, Mark H. Raibert, “Experiments in Balance with a 3D one-legged hopping machine” (International Journal of Robotics Research) the International Journal of Robotics Research), 1984, Vol. 3, No. 2, pp. 75-92).

  An object of the present invention is to provide an excellent robot apparatus capable of autonomously performing a rapid operation such as running or jumping.

  It is a further object of the present invention to provide a robot apparatus and a compliance apparatus for the robot apparatus that realize shock absorption and dynamic operation when performing abrupt operations such as running and jumping.

The present invention has been made in consideration of the above problems, and is a robot apparatus having at least a movable leg,
The link or joint part of the movable leg is composed of a spring element, a damper element, and a friction element, and each element includes a variable nonlinear compliance mechanism that is variable and has nonlinear characteristics.
It is a robot apparatus characterized by this.

  The movable leg of the robot according to the present invention is composed of a linear motion mechanism with one degree of freedom combining a mixed control system composed of an active servo control system and a passive mechanism control system. A mechanism system that is passive and capable of responding in a wide band is arranged in series between a drive system based on active control including a servo motor and an output unit (effector such as a joint). This passive mechanism system can be configured by non-linear elements such as preload, friction and the like in addition to compliance such as springs and dampers.

  Here, in order to realize a passive compliance mechanism, it is difficult to achieve a sufficient performance with a simple spring, and it is preferable to include a nonlinear mechanism element. With respect to this part, the constant or the like can be changed by an actuator or the like. The passive control system is basically realized by machine elements, but may be combined with control means for assisting the passive control system.

  According to the present invention, a dynamic operation such as running or jumping can be realized by introducing a compliance mechanism that can be expanded or contracted or bent into a link or a joint near the shin or ankle of the robot apparatus.

  The robot apparatus according to the present invention further includes a sensor that detects a state of the robot apparatus, and a switching mechanism that stops, brakes, or locks the operation of the variable nonlinear compliance mechanism according to the sensor output. Also good.

  For example, a switching device such as a solenoid for turning on / off the operation of the passive mechanism system is arranged to lock, release, and control the passive mechanism system. In this case, the high frequency response action in the passive mechanism system can be energized or reduced by the switching mechanism control signal from the control processing system.

  The variable nonlinear compliance mechanism may be attached so that its linear motion mechanism matches the link direction of the movable leg, or may be attached so as not to match the link direction of the movable leg. Good.

  For example, consider the case where the compliance mechanism according to the present invention is arranged on the shin. When the robot apparatus takes the standard posture, the shin tilts somewhat forward, so compliance may not function sufficiently if the extension / contraction direction of the driving mechanism is not appropriate. It is necessary to reduce the weight of the robot apparatus body, and it is not realistic to provide rigidity so that the deformation of each frame is minimized. Therefore, it is thought that it is important that the necessary direct elements do not necessarily coincide with the link direction, but rather are arranged in accordance with the motion form.

  In addition, since the variable nonlinear compliance mechanism is considered to be more effective when placed near the grounding portion of the robot apparatus, it should be placed near the grounding portion of the robot apparatus, such as the sole of the foot or the ankle. May be.

  Alternatively, a certain amount of stroke may be required depending on the movement motion of the robot apparatus. Alternatively, the foot mechanism generally needs to be designed to be small and the storage space may be extremely narrow. In such a case, the variable nonlinear compliance mechanism may be disposed near or above the shin of the robot apparatus.

  Also, a multi-axis compliance mechanism may be introduced at one location. In some cases, the compliance mechanism is easier to design in terms of mechanical movement. Alternatively, there are cases where it is desired to have a certain degree of compliance element not only in the linear motion component but also in the rotational direction. For example, it is possible to configure a three-degree-of-freedom compliance mechanism in which a triaxial compliance mechanism is attached so as to connect two vertexes of two triangles facing each other in the linear motion direction. In this case, necessary characteristics can be derived from the dimensional balance of each side of the triangle. Of course, the compliance mechanism placed at one location is not limited to three axes, and by further increasing the number of axes, the anisotropy can be reduced, or any anisotropy (direction dependency) can be set according to the placement balance. You can do it. In addition, such a characteristic is not necessarily applied to only one degree of freedom, but a multi-degree-of-freedom compliance mechanism may be mounted on a part that affects ground adaptability such as an ankle.

  In addition, the variable nonlinear compliance mechanism may be disposed near the rotating portion, or the variable nonlinear compliance mechanism may be disposed in the link portion. In the former case, a single axis is effective, but in order to cope with a direct dynamic impact, it is possible to prevent an unnecessary moment from being applied to the upper body by arranging it on a plurality of axes.

  Further, the spring element constituting the variable nonlinear compliance mechanism according to the present invention may include a nonlinear characteristic, a preload, and a limiter.

  When the load (displacement) of the spring is small, if the spring is too soft, the displacement becomes too large and it is difficult to generate a sufficient support moment. On the other hand, if the spring constant is increased, the characteristic cannot be adapted to the buffer. Therefore, a preload mechanism that does not operate in a low load region and that operates with elastic characteristics when a predetermined load is exceeded, and a limiter mechanism that stops elastic deformation when the amount of displacement reaches a predetermined value are applied to the spring. In such a case, for example, it normally acts as a rigid body and operates only in an emergency, or is displaced with a load when the toes touch the ground. Furthermore, the intentionality of the nonlinearity can improve the consistency between the movement performance and the control characteristics.

  Further, the damper element constituting the variable nonlinear compliance mechanism according to the present invention may have nonlinear characteristics, change characteristics by compression / extension, or have a negative characteristic with respect to speed.

  When a damping element having a simple linear viscosity is applied as a damper, the resistance force becomes too large against a fast disturbance input. That is, the resistance force to a high-speed response becomes large, and when considered with a walking machine, it acts as a rigid body against a sudden force. Therefore, in the present invention, firstly, a characteristic that changes the characteristics in the extension direction and the contraction direction is introduced, and when receiving an impact, the damping force is reduced and absorbed quickly, and when extending, the damping force is set large. Try to suppress the occurrence of overturning moments due to jumping. In addition, it introduces a speed dependency that makes it a negative characteristic with high follow-up characteristics for high-speed input, and the behavior by impact force is extremely fast, and when the speed increases, the resistance force becomes small and quickly displaces. In order to reduce the displacement and impact of the upper body.

  By freely combining these two types of damper characteristics of direction dependency and speed dependency, the impact force can be released and the force for supporting can be appropriately generated. This can be further expanded, and it is possible to give a non-linear characteristic in order to reduce the influence of the natural frequency of the airframe and to induce a steep change.

  Further, the friction element constituting the variable nonlinear compliance mechanism according to the present invention may be a component having a small speed dependency. For example, when the friction element obtains a non-linear elastic characteristic, the deformation remains even if the load is reduced, so that the friction can be obtained by the hysteresis property.

  ADVANTAGE OF THE INVENTION According to this invention, the outstanding robot apparatus which can autonomously perform rapid operation | movements, such as driving | running | working and jumping, can be provided.

  In addition, according to the present invention, it is possible to provide a robot apparatus and a compliance apparatus for the robot apparatus that realize shock absorption and dynamic operation when abrupt operations such as running and jumping are performed.

  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.

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

  FIG. 1 schematically shows a configuration of the degree of freedom of a legged mobile robot that is used to implement the present invention.

  A legged mobile robot that performs biped upright walking is basically a structure in which limbs are attached to a base. The base body here is a control target point that is set near the pelvic link or the trunk that connects the left and right hip joints in the torso portion, or the center of gravity position of the entire robot apparatus or the mass manipulation amount is maximized. The mass operation amount is the mass of a part that can be moved at the same time in the robot apparatus. The part with the maximum mass manipulated variable is the part that can move among the parts in the robot apparatus and corresponds to the part with the maximum mass (even if the mass is the maximum, if the mass cannot be moved, the mass The amount of operation is not the maximum part).

  The robot shown in FIG. 1 has four limbs attached to a base, and has seven degrees of freedom: a shoulder joint pitch axis, a shoulder joint roll axis, an upper arm yaw axis, an elbow joint pitch axis, a forearm yaw axis, a wrist roll axis, and a wrist pitch axis. It is composed of left and right arm portions and left and right leg portions having six degrees of freedom: a hip joint yaw axis, a hip joint roll axis, a hip joint pitch axis, a knee pitch axis, an ankle pitch axis, and an ankle roll axis. The pelvis B1 that connects the left and right hip joints corresponds to the body link, and the upper body is connected to the body link B1 via the lumbar joint of 3 degrees of freedom (roll, pitch, yaw), and the body link B1 has 6 degrees of freedom for the two limbs. Legs and upper body are connected.

  Each of these joint degrees of freedom is actually realized by an actuator / motor. In the present embodiment, a small AC servo actuator of a gear direct connection type and a servo control system integrated into one chip and built in a motor unit is mounted. This type of AC servo actuator is disclosed in, for example, Japanese Patent Laid-Open No. 2000-299970 (Japanese Patent Application No. 11-33386) already assigned to the present applicant.

  An acceleration sensor A1 and a gyro G1 are mounted on the pelvis of the airframe. Also, at the four corners of the left and right soles, there are uniaxial load cells (F1 to F8) for detecting the floor reaction force in the vertical direction of the sole and infrared ranging sensors (D1 to D8) for measuring the distance to the floor, respectively. Four are attached. An acceleration sensor (A2, A3) and a gyroscope (G2, G3) are attached to the center of the left and right soles, respectively.

  FIG. 2 shows an outline of a configuration of a control system introduced for driving control of the legged mobile robot 100. The main control unit (control means) 300 is mounted on a CPU (Central Processing Unit) 301, a RAM (Random Access Memory) 302, a ROM (Read Only Memory) 303 in which operation patterns are stored, and the legged mobile robot 100. An A / D converter 305 that converts an analog signal as an output of various sensors 306 into a digital signal, and a bus 304 that connects these to each other are provided.

  The CPU 301 determines the operation of the legged mobile robot 100 based on the information stored in the ROM 303 and the output of the various sensors 306, and includes the operation command value to the AC servo actuator 307 disposed at each joint. Generate a signal. Then, the CPU 301 applies the generated control signal for each joint to the AC servo actuator 307 connected to the main control unit 300 via the bus 304. Accordingly, each AC servo actuator 307 is operated based on the operation command value included in the control signal, and the legged mobile robot 100 controls various operations including a walking operation.

  The control system according to the present embodiment uses the ZMP as a stability criterion and performs back-house stability control. Here, the stability determination criterion by ZMP is that the gravity and inertial force from the walking system to the road surface and these moments balance with the floor reaction force and the floor reaction force moment as a reaction from the road surface to the walking system. Based on "the principle of". As a result of the dynamic reasoning, there is a point where the pitch and roll axis moment become zero, that is, ZMP, inside the support polygon formed by the sole contact point and the road surface. In this case, a walking pattern is generated / corrected by interpolation calculation using a fifth-order polynomial so that the position, velocity, and acceleration for reducing the deviation from ZMP are continuous.

  In addition, the control system can perform global posture stability control by regarding the motion of the movable part of the robot as a periodic motion and adjusting the phase thereof. One or more phase generators are used in the robot system, and one of a plurality of controllers is selected according to the phase. The controller controls the driving of the movable part based on the continuous interior information. In addition, the actual phase is estimated from the physical system, the frequency and phase of the phase generator are adjusted using this estimated value, and mutual pulling is performed between the physical phase and the phase generator of the robot system. Realize motion control using robot dynamics effectively.

  In this embodiment, by introducing a compliance mechanism that can be expanded or contracted into the link or joint near the shin or ankle of the robot apparatus, a dynamic operation such as running or jumping can be realized.

  Such a compliance mechanism basically includes three elements, that is, a spring, a damper, and friction, and each element is variable and has a nonlinear characteristic. Here, the spring includes a non-linear characteristic, a preload, a limiter, and the like. The damper is assumed to have nonlinear characteristics, change characteristics by compression / extension, or have negative characteristics with respect to speed. In addition, it is assumed that friction is a component having a small speed dependency. When non-linear elastic characteristics are obtained, deformation remains even when the load is reduced, and friction can be obtained by the hysteresis property.

  The variable nonlinear compliance mechanism according to the present embodiment can further include a passive mechanism control system. This passive mechanism control system further includes means for locking and unlocking the compliance mechanism, and means for controlling the lock.

  FIG. 3 conceptually shows the mechanism of the variable nonlinear compliance mechanism according to the present embodiment. The compliance mechanism shown in the figure is composed of a linear motion mechanism with one degree of freedom that combines a mixed control system composed of an active servo control system and a passive mechanism control system. A mechanism system that is passive and capable of responding in a wide band is arranged in series between a drive system based on active control including a servo motor and an output unit (effector such as a joint). This passive mechanism system can be constituted by non-linear elements such as preload, friction and the like in addition to compliance such as a spring and a damper.

  FIG. 4 shows an example in which the variable nonlinear compliance mechanism according to the present embodiment is incorporated around the legs of the robot apparatus. FIG. 5 shows an example in which the compliance mechanism is incorporated in the leg.

  Since it is considered that it is more effective to arrange the variable nonlinear compliance mechanism at a position closer to the grounding portion of the robot apparatus, it may be arranged near the sole or ankle as shown in FIG.

  In addition, a certain amount of stroke may be required depending on the movement motion of the robot apparatus. Alternatively, the foot mechanism generally needs to be designed to be small and the storage space may be extremely narrow. In such a case, as shown in FIG. 5, it may be desirable to arrange the compliance mechanism in the vicinity of or above the shin.

  In the example shown in FIGS. 4 and 5, the operation direction of the variable nonlinear compliance mechanism is assumed to be both rotation and translation. Further, when the compliance mechanism is attached to a corresponding part of the robot apparatus, the operation direction is not necessarily limited to the link axis direction. For example, as shown in FIG. 6, it can be adapted to the operational purpose and dimensional relationship of the robot apparatus by being attached in an arbitrary direction with respect to the link shaft.

  For example, consider the case where the compliance mechanism according to the present invention is arranged on the shin. When the robot apparatus takes the standard posture, the shin tilts somewhat forward, so compliance may not function sufficiently if the extension / contraction direction of the driving mechanism is not appropriate. It is necessary to reduce the weight of the robot apparatus body, and it is not realistic to provide rigidity so that the deformation of each frame is minimized. Therefore, it is thought that it is important that the necessary direct elements do not necessarily coincide with the link direction, but rather are arranged in accordance with the motion form.

  In addition, only a single-axis compliance mechanism is not necessarily attached at one attachment site. For example, as shown in FIG. 7, it is also possible to introduce a multi-axis compliance mechanism at one location.

  In some cases, the compliance mechanism is easier to design in terms of mechanical movement. Alternatively, there are cases where it is desired to have a certain degree of compliance element not only in the linear motion component but also in the rotational direction. In the example shown in FIG. 7, necessary characteristics can be derived from the dimensional balance of each side of the triangle. Of course, the compliance mechanism placed at one location is not limited to three axes, and by further increasing the number of axes, the anisotropy can be reduced, or any anisotropy (direction dependency) can be set according to the placement balance. You can do it. In addition, such a characteristic is not necessarily applied to only one degree of freedom, but a multi-degree-of-freedom compliance mechanism may be mounted on a part that affects ground adaptability such as an ankle.

  A plurality of variable nonlinear compliance mechanisms according to the present invention can be introduced on the movable leg.

  FIG. 8 shows a state in which the variable nonlinear compliance mechanism is introduced for each joint constituting the movable leg, such as the hip joint, the knee, and the ankle, as an example in which the variable nonlinear compliance mechanism is arranged near the rotating portion. In this case, although a single axis is effective, in order to cope with a direct dynamic impact, it is possible to prevent an unnecessary moment from being applied to the upper body by arranging it on a plurality of axes.

  In addition, FIG. 9 shows a state in which the compliance mechanism is introduced for each link shaft constituting the movable leg such as the thigh, the lower leg, and the foot as an example in which the variable nonlinear compliance mechanism is arranged in the link part. ing.

  8 and 9, in consideration of the characteristics required when the robot apparatus performs walking or other legged movements, the compliance mechanism is provided at a position closer to the foot tip or the ground contact surface. Arrangement improves the buffer effect and other ground adaptability. On the other hand, from the viewpoint of reducing the inertial force, it is better not to place a heavy object at the tip as much as possible. Therefore, it is necessary to appropriately distribute and arrange the compliance mechanism according to the movement state and scale of the robot.

  The variable nonlinear compliance mechanism shown in FIG. 3 is a linear motion mechanism that realizes the concept of a mixed control system including an active servo control system and a passive mechanism control system.

  In the example shown in the figure, a mechanism system that can respond passively and in a wide band is arranged in series between the active control system consisting of a servo motor and the output section (effector such as a joint). Has been. This passive mechanism system can be constituted by non-linear elements such as preload, friction and the like in addition to compliance such as a spring and a damper. Further, another link or joint may be included between the passive mechanism system and the output unit. The mechanism element may be an electric system such as a coil.

  Here, in order to realize a passive compliance mechanism, it is difficult to achieve a sufficient performance with a simple spring, and it is preferable to include a nonlinear mechanism element. With respect to this part, the constant or the like can be changed by an actuator or the like. The passive control system is basically realized by machine elements, but it is also assumed that a control means for assisting the passive control system is combined.

  In the example shown in FIG. 3, a switching device such as a solenoid for turning on / off the operation of the passive mechanism system is arranged, and the passive mechanism system is locked, released, and controlled. That is, the high frequency response action in the passive mechanism system can be energized or deenergized by the switching mechanism control signal from the control processing system.

  Of course, the desired operation and effect of the present invention can be achieved without being combined with the passive mechanism control system as described above, but it is possible to perform fine control with higher performance.

  Below, each element which comprises a passive mechanism control system, such as a spring and a damper, is demonstrated.

Spring FIG. 10 shows the elastic characteristics of a normal linear spring. Applying such a simple spring is inappropriate for ensuring stability. This is because even if an attempt is made to generate the necessary support moment, if the displacement is small, it is not sufficiently transmitted and may cause a fall. In this case, when the load (displacement) of the spring is small, if the spring is too soft, the displacement becomes too large and it is difficult to generate a sufficient support moment. On the contrary, when the spring constant is increased, the characteristics cannot be adapted to the buffer. That is, it is difficult to directly use it for a legged mobile robot, and there may be problems such as an unnecessarily large stroke or vibration. Also, the spring element is generally difficult to control to determine the position.

  Therefore, in this embodiment, the preload mechanism that operates when the predetermined load is exceeded without operating in the low load region and the limiter mechanism that stops elastic deformation when the displacement reaches a predetermined value are used as springs. Applicable. The spring characteristics in this case are as shown in FIG. 11, and an offset (bias) is given to moderately suppress the spring constant and improve the characteristics in the low load region.

  By obtaining a spring characteristic as shown in FIG. 11, for example, it can act as a substantially rigid body at normal times and operate only in an emergency, or can be displaced with a load at the time of ground contact with the foot.

  In addition, when similar characteristics are realized by controlling a mechanism such as a switching mechanism instead of a mechanical positional relationship, it includes that shown in FIG. Alternatively, it is possible to improve the consistency between the movement performance and the control characteristics by intentionally imparting non-linearity.

  Combining functions with preload, displacement stopper, non-linear characteristic spring, etc. is effective. In addition, if the connection of these elements has an extreme step (discontinuity), the behavior is disturbed, so it is necessary to consider characteristics that change smoothly.

Damper FIG. 13 shows the characteristics of a damper serving as a basic model. The damper shown is a damping element with linear viscosity. If such a simple characteristic is applied, the resistance force becomes too large against a fast disturbance input. That is, the resistance force to a high-speed response becomes large, and when considered with a walking machine, it acts as a rigid body against a sudden force. For this reason, after all, it causes a fall moment. The following two methods are introduced as countermeasures.

(1) The characteristics change in the extension direction and the contraction direction. (2) A negative characteristic with high follow-up characteristics for high-speed input.

  FIG. 14 shows the characteristics of the damper that has introduced the first method and has given different characteristics depending on the direction. In other words, it is effective to change the damping rate according to the direction in which the load is applied. When receiving an impact, the damping force is reduced to absorb quickly, and when extending, the damping force is set to be large, and the falling moment of jumping is reduced. Try to suppress the occurrence.

  FIG. 15 shows a speed-dependent damper characteristic in which the second method is introduced and the characteristic is switched according to the speed at which the system operates. The behavior due to the impact force is extremely fast, and it is desirable to reduce the displacement and impact of the upper body by quickly displacing the resistance force as the speed increases. As shown in FIG. 15, this function can be realized by giving a negative characteristic to the damper.

  By freely combining the damper characteristics shown in FIG. 14 and FIG. 15, it is possible to release an impact force and appropriately generate a support force. This is further expanded to give non-linear characteristics in order to reduce the influence of the natural frequency of the aircraft and to prevent abrupt changes. FIG. 16 shows an example of the damper characteristic in this case. For the compliance mechanism, it becomes more effective by combining a different characteristic depending on the direction, a negative characteristic due to speed, and a nonlinear damping mechanism. However, since an extreme step in the connection of these elements causes disturbance in behavior, it is necessary to consider characteristics that change smoothly.

  In addition to the spring and the damper, characteristics can be improved by appropriately introducing factors such as friction.

To switch the characteristics of the switching mechanism passive mechanism control system, a preload, a latch or solenoid, a brake mechanism, etc., or a combination thereof can be introduced.

  When the load or speed increases, the operation starts passively or the switching operation is clarified by giving control. Alternatively, it can be used to create the characteristics themselves.

  FIG. 17 shows a configuration example of a mechanism unit that organically combines the above-described spring, damper, and switching mechanism.

  The non-linear spring element is composed of an indefinite pitch, multiple springs, or the like. The limit mechanism has a buffer portion, and it is preferable to use a buffer material instead of stopping it suddenly with a stopper. A preload mechanism acts on the spring. A brake or a latch is used as a locking mechanism. Both passive and active control systems are equipped with a locking mechanism.

  In addition, the resistance of the damper varies between the forward path and the return path. The characteristic of being asymmetric between the forward path and the return path is, for example, a high load applied only when the supporting leg is used, such as walking, and hardly any load is applied during the swinging leg. For the nonlinear damping mechanism, an electric system such as solid friction or a coil can be used in addition to a fluid.

  FIG. 18 shows a state where the variable nonlinear compliance mechanism according to the present embodiment is mounted on the lower leg (shin) of the movable leg.

  In the case of illustration, it is possible from a design surface to bend and arrange | position in the range of about ± 30 degree | times to a pitch or a roll direction with respect to direction axes, such as a shin link. In the case of a biped walking robot apparatus, it is not realistic to advance completely as long as it has a link configuration, so such an arrangement is necessary.

  FIG. 19 shows a state in which the variable nonlinear compliance mechanism according to this embodiment is mounted in combination with an arbitrary link mechanism in the lower leg portion of the movable leg. In the case of illustration, the effective operation direction and rotation axis of the compliance mechanism can be set and adjusted.

  If it is desired to realize a compliance climate with a linear motion element or an extremely large radius of curvature, it is conceivable to construct a parallel link mechanism as shown in the figure. In this case, the rotation center can be arranged at an arbitrary position by simply changing the link length, and a relatively strong mechanism system can be realized.

  FIG. 20 shows a state in which a biped walking type legged mobile robot in which the variable nonlinear compliance mechanism according to the present embodiment is introduced into the lower leg (shin) of each movable leg performs a walking motion. FIG. 21 shows a state in which a legged mobile robot in which the compliance mechanism is introduced to the foot of each movable leg performs a walking motion.

  The smaller the scale of the robot apparatus, the more severely limited the storage space mechanically. Also, the distance between the sole and the ankle shaft should be as small as possible. Therefore, as shown in FIG. 20, it is possible to secure a sufficient stroke and a necessary operation axis by arranging the compliance mechanism on the shin or thigh having a relatively large margin. When the leg lands, the compliance mechanism operates to absorb the primary impact, and the lock mechanism operates near the contraction limit, and the position is maintained. As a result, it is possible to suppress the occurrence of a tipping moment due to the wobbling of the airframe and to secure a support moment. Further, when the foot is separated, the lock mechanism is released to deal with the next landing. Depending on how the lock mechanism is released, it can be an aid to running and walking. It can be used for the movement control by using the release of the lock mechanism at the moment when it is completely free or when it is separated.

  On the other hand, when the compliance mechanism is designed to be small and light, as shown in FIG. 21, the impact can be efficiently absorbed by disposing the compliance mechanism closer to the moving surface. When the compliance mechanism is attached in the vicinity of the foot or ankle, the compliance mechanism is activated to absorb the primary impact when the foot is landed, the lock is activated near the contraction limit, and the position is maintained. As a result, it is possible to suppress the occurrence of a tipping moment due to the wobbling of the airframe and to secure a support moment. Further, when the foot is separated, the lock mechanism is released to deal with the next landing. Depending on how the lock mechanism is released, it can be an aid to running and walking. It can be used for the movement control by using the release of the lock mechanism at the moment when it is completely free or when it is separated.

  However, the passive characteristic of the variable nonlinear compliance mechanism according to the present embodiment can be obtained by operating the displacement stopper. Further, the active characteristic of the compliance mechanism can be obtained by the above switching mechanism.

  As shown in the drawings, first, the foot tip comes in contact with the ground, and the load increases, so that it is displaced from the vicinity exceeding a certain condition. When the load is sufficiently applied, sufficient support moment, position and posture accuracy are required, and the lock mechanism is activated.

  In an operation in which the hind leg kicks off the road surface during the walking motion, a force to kick out can be generated by releasing them.

  According to the present invention, by introducing a non-linear compliance mechanism element whose characteristics can be arbitrarily set / adjusted to the movable leg of the robot apparatus, the movement performance can be dramatically improved.

High-speed movement According to the present invention, the robot apparatus can be moved at high speed. Specifically, it is a running operation or a jumping operation. For such an operation, it is necessary to introduce a completely different control concept from walking. As described above, there is no motor / servo system that can respond to a high-speed response, in particular, a high frequency (high-speed) input, so the variable nonlinear compliance mechanism according to the present invention is considered to be effective.

Improving the ability to adapt to unevenness If the unevenness of the road surface on which the robot apparatus moves becomes severe, even if the moving speed is slow, it is necessary to move at high speeds at each joint of the leg, particularly at the end. If the movement of the joint cannot keep up with the change in the road surface, a moment that causes an unstable state, such as the aircraft falling over, will be generated. On the other hand, when the variable nonlinear compliance mechanism according to the present invention is applied to a joint or a link, it can be effectively adapted to an unexpected disturbance on the moving surface.

Realization of excellent walking motion The conventional rigid leg mechanism exhibits its performance by accurately detecting the state and positioning accurately. For this reason, there is an aspect in which high-speed disturbance cannot be dealt with. On the other hand, according to the present invention, the control method itself is greatly changed by incorporating the compliance element. For example, when the compliance mechanism is equipped with a latch mechanism or a similar mechanism, walking that improves stability on rough terrain can be realized by walking to press the foot against the ground.

Walking motion Conventional rigid leg mechanisms have demonstrated their performance by accurately detecting the state and positioning accurately. In this case, there is an aspect that the control system cannot cope with high-speed disturbance. On the other hand, according to the present invention, the control method itself is greatly changed by introducing the compliance element into the control system. For example, it is possible to improve the stability on rough terrain by equipping a latch mechanism and walking so as to press the foot against the ground.

Corresponding to various types of movements The variable nonlinear compliance mechanism according to the present invention includes elements for switching between passive and active operations. For example, it operates almost rigidly during normal walking, but the compliance element is activated during traveling when the force is large and the speed is increased. These control operations are fundamentally different, and it is generally difficult to cope with the same mechanism model. However, according to the present invention, it is possible to reconfigure a mechanism model suitable for each scene. .

Improving expressiveness Currently, the performance of robotic devices is still in the development stage, and it is necessary to show various performances. The expressive power of the movement is one of them, but by providing a compliance element, it is possible to select the ground contact state of the sole without using precise force control. For example, when making a humanoid robot device perform a choreographic movement, the degree of freedom of joints of the robot is generally insufficient for design reasons, but it is possible to operate like a sliding foot using a compliance element. Therefore, even if the leg mechanism is not redundant, a redundant operation can be realized, and the range of expressive power is expanded.

Buffering The variable nonlinear compliance mechanism according to the present invention has an impact absorbing effect. The shock absorbing effect works effectively over almost all operations of the robot apparatus. Moreover, unlike simply introducing a spring as a compliance element, it can be given a characteristic that does not impair controllability, so it can be operated preferentially and selectively under conditions that require protection of the mechanism. It is.

Improvement of energy conversion efficiency In the variable nonlinear compliance mechanism system according to the present invention, an element for dissipating energy is introduced, but energy consumption is not necessarily increased. This is because weight reduction and dispersion of peak power can be expected in spite of the technique capable of realizing the above. First, when it comes to high-speed movement, the actuator does not do all the work, but the compliance element can accept it temporarily, or the damping element can handle the force in the direction of gravity. The control operation itself can be changed. For example, the motor can be set small. As a result, the scale of the power source can be reduced, and a synergistic effect can be obtained in that there is a margin in drive capability. Therefore, a high-performance robot apparatus that is efficient in terms of energy can be realized. In other words, a small actuator is generally excellent in high-speed response, and the robot apparatus is very advantageous for realizing dynamic 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.

  The gist of the present invention is not necessarily limited to a product called a “robot”. That is, if it is a mechanical device or other general mobile device that performs a movement resembling human movement using electrical or magnetic action, it is a product belonging to another industrial field such as a toy. Even if it exists, this invention can be applied similarly.

  In short, the present invention has been disclosed in the form of exemplification, and the description of the present specification 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.

FIG. 1 is a diagram schematically showing a configuration of a degree of freedom of a legged mobile robot used for carrying out the present invention. FIG. 2 is a diagram showing an outline of the configuration of the control system of the legged mobile robot 100. FIG. 3 is a diagram conceptually showing the mechanism of the variable nonlinear compliance mechanism according to one embodiment of the present invention. FIG. 4 is a view showing an example in which the variable nonlinear compliance mechanism according to the present invention is incorporated around the legs of the robot apparatus. FIG. 5 is a view showing an example in which the variable nonlinear compliance mechanism according to the present invention is incorporated in the leg of the robot apparatus. FIG. 6 is a view showing a state where the variable nonlinear compliance mechanism according to the present invention is attached to the link shaft in an arbitrary direction. FIG. 7 does not show a state where a multi-axis compliance climate is introduced at one location. FIG. 8 is a diagram showing a state where a variable nonlinear compliance mechanism is introduced for each joint constituting the movable leg. FIG. 9 is a diagram showing a state where a variable nonlinear compliance mechanism is introduced for each link shaft constituting the movable leg. FIG. 10 is a diagram showing the elastic characteristics of a normal spring. FIG. 11 is a diagram showing the elastic characteristics of the spring when the limiter mechanism and the preload mechanism are applied. FIG. 12 is a diagram showing the elastic characteristics of the spring when the limiter mechanism and the preload mechanism are applied. FIG. 13 is a diagram illustrating the characteristics of a damper serving as a basic model. FIG. 14 is a diagram showing the characteristics of the damper given different characteristics depending on the direction. FIG. 15 is a diagram showing a speed-dependent damper characteristic. FIG. 16 is a diagram showing a damper characteristic to which a nonlinear characteristic for preventing a steep change is given. FIG. 17 is a diagram illustrating a configuration example of a mechanism unit in which a spring, a damper, and a switching mechanism are organically combined. FIG. 18 is a diagram showing a state where the variable nonlinear compliance mechanism according to the present invention is mounted on the lower leg of the movable leg. FIG. 19 is a diagram showing a state in which the variable nonlinear compliance mechanism according to the present invention is mounted on the lower leg of the movable leg in combination with an arbitrary link mechanism. FIG. 20 is a diagram showing a state in which a biped walking type legged mobile robot in which the variable nonlinear compliance mechanism according to the present invention is introduced into the lower leg of each movable leg performs a walking motion. FIG. 21 is a diagram showing a state in which a biped walking type legged mobile robot in which the variable nonlinear compliance mechanism according to the present invention is introduced to the foot of each movable leg performs a walking motion.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Leg type mobile robot 300 ... Main control unit 301 ... CPU
302 ... RAM
303 ... ROM
304 ... Bus 307 ... AC servo actuator

Claims (24)

A robot apparatus having at least movable legs,
The link or joint part of the movable leg is composed of a spring element, a damper element, and a friction element, and each element includes a variable nonlinear compliance mechanism that is variable and has nonlinear characteristics.
A robot apparatus characterized by that. A sensor for detecting a state of the robot device;
A switching mechanism for stopping, braking, or locking the operation of the variable nonlinear compliance mechanism according to the sensor output;
The robot apparatus according to claim 1, further comprising: The variable nonlinear compliance mechanism is attached so that its linear motion mechanism matches the link direction of the movable leg.
The robot apparatus according to claim 1. The variable nonlinear compliance mechanism is attached so that its linear motion mechanism does not coincide with the link direction of the movable leg.
The robot apparatus according to claim 1. The variable nonlinear compliance mechanism is disposed near a grounding portion of the robot apparatus.
The robot apparatus according to claim 1. The variable nonlinear compliance mechanism is disposed near or above the shin of the robot apparatus,
The robot apparatus according to claim 1. Introducing a multi-axis compliance mechanism in one location,
The robot apparatus according to claim 1. Arranging the variable nonlinear compliance mechanism in the vicinity of the rotating part;
The robot apparatus according to claim 1. Arranging the variable nonlinear compliance mechanism in the link part;
The robot apparatus according to claim 1. The spring element has non-linear characteristics, preload, limiter,
The robot apparatus according to claim 1. The damper element has non-linear characteristics, changes characteristics by compression / extension, or has negative characteristics with respect to speed.
The robot apparatus according to claim 1. The friction element is a component having a small speed dependency,
The robot apparatus according to claim 1. A compliance device for a robotic device having at least movable legs,
It is arranged at the link or joint part of the movable leg, and is composed of a spring element, a damper element, and a friction element, and each element is variable and has a non-linear characteristic.
A compliance device for a robot device characterized by that. A sensor for detecting a state of the robot device;
A switching mechanism for stopping, braking, or locking the operation of each element according to the sensor output;
The compliance device for a robotic device according to claim 13, further comprising: The linear motion mechanism of the compliance device is attached so as to coincide with the link direction of the movable leg,
A compliance device for a robotic device according to claim 13. It is attached so that the linear motion mechanism of the compliance device does not coincide with the link direction of the movable leg,
A compliance device for a robotic device according to claim 13. It is arranged near the grounding part of the robot device,
A compliance device for a robotic device according to claim 13. Arranged near or above the shin of the robotic device,
A compliance device for a robotic device according to claim 13. A plurality of axes are simultaneously introduced into one place of the robot apparatus;
A compliance device for a robotic device according to claim 13. It is arranged near the rotating part of the movable leg of the robot device,
A compliance device for a robotic device according to claim 13. Arranged in the link portion of the movable leg of the robot apparatus,
A compliance device for a robotic device according to claim 13. The spring element has non-linear characteristics, preload, limiter,
A compliance device for a robotic device according to claim 13. The damper element has non-linear characteristics, changes characteristics by compression / extension, or has negative characteristics with respect to speed.
A compliance device for a robotic device according to claim 13. The friction element is a component having a small speed dependency,
A compliance device for a robotic device according to claim 13.

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