JP2006051558A - Bipedal walking robot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain the amount of power consumed by a roll joint of a hip joint in walking in a bipedal walking robot. <P>SOLUTION: This bipedal walking robot has a leg 002 composed of a plurality of link members and a joint part connecting the respective link members to each other, and the robot is caused to walk by the drive of the leg 002. In a roll joint 008 for rocking the body of the bipedal walking robot round the roll axis among the leg joints, a mechanical energizing means 036 for mechanically generating stable turning moment depending on the roll angle in the roll axis in a predetermined rotating direction on the opposite side to the rotating direction of turning moment round the roll axis due to a predetermined weight generated in walking of the bipedal walking robot is provided in parallel to the roll joint 008. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a biped walking robot having two legs and capable of walking with the legs.

Legged robots have a high ability to adapt to stairs or steps and rough terrain, and can adapt well to human living spaces, but they tend to consume significantly more energy than robots with wheeled movement mechanisms. . This is because a wheeled robot does not consume special energy to maintain its posture, whereas a legged robot is forced to consume energy by servo control. The present applicant previously provided a mechanical brake device at a joint part constituting the leg as an energy-saving measure technique for the legged robot, and actuates the brake when maintaining the posture at that time, and also drives the joint motor. If the joint movement direction by external force such as gravity and the direction in which the joint is driven coincide with the technology that cuts off the power supply to the joint, a weak braking force is applied to the joint to consume the drive motor. A technique for saving electric power has been proposed (see, for example, Patent Document 1).

  This technique cannot be applied when the direction in which an external force such as gravity acts on the joint to rotate and the direction in which the joint is driven by the control are different. Moreover, in the usage which applies a weak brake, since the energy of movement is changed into the heat energy of friction by a brake, the energy saving effect may not necessarily be enough depending on the case.

  In addition, a balancer spring is used for the robot in order to reduce the load on the robot. For example, in the field of industrial robots, there is an example in which a balancer spring is provided for the purpose of canceling out part of the weight moment of a workpiece acting on a joint. In particular, a robot that lifts the automobile itself in the automobile manufacturing process applies a large load moment to the joint near the mounting base, and thus a joint provided with a balancer spring has been used conventionally. In this example, expecting the advantage of requiring less motor torque in the vertical direction (that is, the labor-saving advantage of having a smaller motor with a smaller capacity), and less energy consumption when moving the workpiece in the horizontal direction. It can be interpreted as an expectation of the advantage of moving with.

Furthermore, in the field of walking robots, a technique using this balancer spring has been proposed (see, for example, Patent Documents 2 and 3). This technique uses a pneumatic spring instead of a metal spring and is attached to the knee joint, and shows a concept of labor saving for designing a robot with a smaller motor. In addition, as a problem peculiar to the knee joint, it is the swing leg period (a period when the leg is not in contact with the walking road surface. In the following, the state of the leg that is not in contact with the walking road surface is referred to as “free leg state”. There is a fact that the knee bends greatly, and a complicated mechanism for disabling the balancer spring is added during the swing phase to cope with this fact.
JP 2003-11079 A JP 2003-103480 A JP 2003-145477 A

In a biped walking robot having two legs, when observing the movement during walking, each leg is in the stance phase (the period when the leg is in contact with the walking road surface. In order to maintain the robot's posture in a stable manner, the leg that is in contact with the ground is called “Standing”. The weight is shifted so that the vertical line penetrates the sole on the stance side. Of course, the inertial force that accompanies the exercise is also working, so if you express more accurately, the weight is moved so that the resultant force of gravity and inertial force acting on the center of gravity penetrates the foot contact surface on the standing leg side. Should be said. Since the inertial force is small, hereinafter, the inertial force is omitted for simplification of description.

  Of course, when one leg is in the stance phase and the other leg is in the swing phase, the gravity of all members placed above the joint acts as a moment on the joint that carries the roll of the hip joint. That is, gravity acting on the free leg also acts as a moment. Accordingly, the position control for walking is performed while the sum of these moments (hereinafter referred to as “load moment during walking”) is constantly acting on the joint that bears the roll (hereinafter referred to as “roll joint”). It is running. Therefore, unless electric energy for work corresponding to these loads is supplied to the motor of the roll joint, the balance of the robot is lost and walking cannot be continued.

  On the other hand, if electric energy against the load moment during walking is continuously supplied to the control motor of the roll joint while the walking robot is walking, the electric energy consumption for walking may become significant.

  In view of the above problems, an object of the present invention is to suppress the amount of power consumed by a roll joint of a hip joint during walking in a biped walking robot.

  In the present invention, in order to solve the above-described problems, mechanical biasing means that exerts a biasing force without consuming electric energy is installed in parallel with the roll joint. When walking with a biped robot, the roll joint must always be controlled alternately between the standing and swinging legs, so a periodic gravity load is applied to the roll joint to maintain the balance during walking. It takes. Therefore, by supporting the operation of the biped walking robot at the roll joint by this mechanical biasing means, it is possible to suppress the electric energy consumed at the roll joint when the biped walking robot is walking.

  More specifically, the present invention is a biped robot that has two legs each composed of a plurality of link members and joints that connect each of the link members, and walks by driving the legs. In the hip joint that swings the body of the biped walking robot around the roll axis among the joints of the legs, the rotational direction of the rotational moment around the roll axis due to a predetermined weight generated when the biped walking robot walks, The biped robot includes mechanical urging means for generating a stable rotational moment mechanically in accordance with the roll angle on the roll axis in parallel to the roll joint in a predetermined rotational direction on the opposite side.

  Here, the roll joint refers to the joint of the leg of the biped robot as described above and bears the roll of the hip joint. Then, by swinging the body of the biped walking robot around the roll axis provided in the roll joint, the body of the biped walking robot is swung left and right. When a biped robot walks, one leg is in contact with the walking road surface and the other leg is not in contact with the walking road surface, and one leg is not in contact with the walking road surface and the other leg is walking. The state of being in contact with the road surface is repeated. That is, in one leg, the standing state and the free leg state are alternately repeated. As a result, a rotational moment due to a gravity load is periodically applied to the roll joint.

That is, the rotational moment due to the gravitational load is the rotational moment around the roll axis due to the predetermined weight. The predetermined weight is a partial weight of the biped walking robot that is applied to the roll joint by the walking motion of the biped walking robot when the biped walking robot is walking. Therefore, the rotational moment around the roll axis due to the predetermined weight varies depending on the position and posture of the biped robot when walking.

  When the biped robot walks, in order to maintain the balance of the entire robot, it is necessary to apply a rotation moment against the rotation axis around the roll axis from a predetermined weight to the roll axis from the outside. Therefore, when walking with a biped walking robot, electric energy is consumed at the roll axis just to keep the balance during walking of the biped walking robot without working outside, and the power consumption increases.

  Therefore, in the biped robot according to the present invention, at least a part of the rotational moment around the roll axis due to the predetermined weight is canceled by the stable rotational moment that is the biasing force by the mechanical biasing means. A stable rotation moment, which is an urging force by the mechanical urging means, is mechanically generated, and the rotation direction is a predetermined rotation direction opposite to the rotation moment due to a predetermined weight. Here, mechanical means “without consuming electric energy”, and mechanical urging means does not consume electric energy, unlike a motor that performs the original position control of the roll shaft. Generate a biasing force. By this mechanical biasing means, a part of the rotational moment around the roll axis due to the stable rotational moment and the predetermined weight is offset, and as a result, the amount of electric power consumed by the roll joint motor to maintain the balance during walking is reduced. It becomes possible to suppress. The stable rotational moment is determined in accordance with the roll angle related to the magnitude of the rotational moment in order to more efficiently reduce the rotational moment generated by the predetermined weight. Here, the roll angle refers to the rotation angle of the leg with respect to the roll axis.

  Here, in the above biped robot, when the roll joint is a roll joint of a leg that is in contact with a walking road surface when the biped robot is walking, the predetermined weight is at least the biped It may be the weight of the leg that is not in contact with the walking road surface and the upper body of the biped robot when the walking robot is walking. That is, when only one leg is standing, the body of the biped robot is supported by the one leg. At that time, the leg roll joints in the standing state include the upper body of the biped robot (the body part of the biped robot on the head side from the leg) and the weight of one leg in the swinging state. Rotational moment due to is generated around the roll axis.

  Here, when attention is paid to one leg of a biped robot, the leg alternately enters a standing leg state and a free leg state during walking. At this time, the direction of the rotational moment due to the predetermined weight applied to the roll joint of the one leg may be opposite between the standing time and the free leg time, based on the balance of the biped robot during walking. Furthermore, as described above, the predetermined weight is greatly different between the standing leg time and the free leg timing. In other words, the predetermined weight at the swinging leg time is basically the weight of the leg in the swinging leg state, and is much smaller than the predetermined weight at the standing leg time.

  Therefore, the roll joint encounters rotational moments having opposite directions and different sizes in the stance phase and the swing phase. And if the direction of the stable rotational moment by the mechanical biasing means is constant, in some cases it is not possible to cancel a part of the rotational moment due to the predetermined weight, on the contrary, to increase the rotational moment due to the predetermined weight, The amount of power required to maintain the balance during walking increases.

  In other words, when the direction of the stable rotational moment and the rotational moment due to the predetermined weight are opposite, a part of the rotational moment due to the predetermined weight is offset by the stable rotational moment, so the power consumption for maintaining the balance during walking However, when the direction of the stable rotation moment and the rotation moment due to the specified weight is the same, the stable rotation moment is added to the rotation moment due to the constant weight. Will increase.

  Therefore, in the above biped robot, the roll joint is a leg roll joint that is in contact with the walking road surface when the biped robot is walking, and the predetermined weight is at least the two biped robots. When the weight of the leg that is not in contact with the walking road surface and the upper body of the biped robot when the leg walking robot is walking, the mechanical biasing means is stable around the roll axis in the predetermined rotation direction. A rotational moment may be generated and a stable rotational moment around the roll axis may not be generated in a direction opposite to the predetermined rotational direction.

  The predetermined rotation direction here refers to the direction of the rotational moment around the roll axis generated by a predetermined weight consisting of at least the upper body of the biped walking robot and the leg in the free leg state at the roll joint of the leg in the standing state. Is the opposite direction. Therefore, the stable rotational moment by the mechanical biasing means is set so as to cancel only the rotational moment when the predetermined weight becomes relatively large. As a result, when the rotational moment due to the predetermined weight during walking is relatively large, a part of the rotational moment can be offset by the stable rotational moment, and when the rotational moment due to the predetermined weight is relatively small, Since the moment is not increased, the amount of power consumed by the roll joint during walking can be suppressed.

  Further, in the above biped robot, the roll joint is a roll joint of a leg that is in contact with a walking road surface when the biped robot is walking, and the predetermined weight is at least the two biped robots. When the weight of the leg that is not in contact with the walking road surface and the upper body of the biped robot when the leg walking robot is walking, the mechanical biasing means is stable around the roll axis in the predetermined rotation direction. A rotational moment may be generated, and a stable rotational moment smaller than the stable rotational moment in the predetermined rotational direction may be generated in a direction opposite to the predetermined rotational direction.

  The predetermined rotation direction here is also synonymous with the above-mentioned predetermined rotation direction. In this case, the stable rotational moment by the mechanical biasing means is relatively large in the rotational direction in which the rotational moment due to the predetermined weight is relatively large, and conversely becomes relatively small in the rotational direction in which the rotational moment is relatively small. In other words, the mechanical urging means generates a stable rotational moment according to the magnitude of the rotational moment in each rotational direction generated by a predetermined weight, so that a part of each rotational moment can be canceled out. The amount of power consumed by the roll joint during walking can be suppressed.

  Here, in the above-described biped robot, the mechanical biasing means is a spring member, and both ends of the spring member are respectively connected to the legs at upper and lower portions sandwiching the roll shaft, and At least one end of the spring member may be connected to the leg in a state having a play area within a predetermined range.

The spring member is connected to the upper and lower leg parts across the roll axis of the roll joint, so that when the leg position is controlled around the roll axis during walking, the spring member is expanded and contracted and the urging force is increased. The generated urging force becomes a stable rotational moment around the roll axis. Here, at least one end of the spring member is provided with a play portion. This play portion is for creating a neutral state in which the spring member is not expanded or contracted by the movement of the leg when the position control of the leg around the roll axis during walking is performed. In other words, depending on the play portion, depending on the movement of the leg during walking, a biasing force by the spring member is not generated, so that a stable rotational moment around the roll axis is generated in the predetermined rotational direction, and the direction opposite to the predetermined rotational direction. The stable rotational moment around the roll axis is prevented from being generated in the direction of, or the stable rotational moment around the roll axis is generated in the predetermined rotational direction, and the predetermined rotational direction is opposite to the predetermined rotational direction. It is possible to generate a stable rotational moment that is smaller than the stable rotational moment in the case of the rotational direction.

  In the biped robot described above, the mechanical biasing means is a rotary spring member, and one end of the rotary spring member is connected to the leg and the other end is connected to the roll shaft. In addition, at least one of the one end and the other end may be connected to the leg in a state having a play area in a predetermined range.

  When the roll shaft and the leg are connected by the rotation spring member, when the position control of the leg around the roll axis is performed during walking, the rotation spring member is twisted and elastic energy is accumulated, and the roll shaft is directly connected to the roll shaft. A stable rotational moment is generated. Here, at least one of the one end and the other end of the rotary spring member is provided with a play portion. This play portion is for creating a neutral state in which the rotation spring member is not twisted by the movement of the leg when the leg position is controlled around the roll axis during walking. That is, depending on the play portion, depending on the movement of the legs during walking, a stable rotational moment by the rotary spring member is not generated, so that a stable rotational moment around the roll axis is generated only in the predetermined rotational direction, and the predetermined rotational direction The stable rotation moment around the roll axis is not generated in the direction opposite to the roll axis, or the stable rotation moment around the roll axis is generated in the predetermined rotation direction, and in the direction opposite to the predetermined rotation direction. It is possible to generate a stable rotational moment smaller than the stable rotational moment in the predetermined rotational direction.

  Here, in the biped robot described above, the central axis of the rotary spring member may be concentric with the roll axis. As a result, it is possible to mount the rotary spring member, which is a mechanical biasing means, in a more space-saving manner, and it is possible for the rotary spring member to contact, entrain, etc. with other components of the biped robot. It can be lowered.

  Here, in the biped robot up to the above, the mechanical biasing means increases the stable rotational moment as the roll angle increases, and increases the stable rotational moment as the roll angle increases. The increase rate may be reduced.

  Considering two cases, when the biped robot walks on a flat ground and when going up and down the stairs, the knee joint is bent greatly during the stance phase on the stairs, and as a result, the distance between the hip joint and the ankle joint is shortened. However, because of the stability of walking, the vertical line drawn from the center of gravity of the robot must pass through the ground contact surface of the leg. This fact means that when the knee is bent greatly, the roll angle of the roll joint is larger in stair walking than in flat ground walking. However, on the other hand, the load moment applied to the roll joint during stair walking does not increase much as compared with walking on flat ground. Therefore, if the characteristic of the stable rotational moment by the mechanical biasing means is set to increase in proportion to the roll angle, a stable rotational moment greater than the rotational moment due to the predetermined weight will occur when walking on stairs. On the contrary, the amount of power consumption increases. Moreover, when the stable rotational moment corresponding to walking on flat ground is optimized, the amount of power consumption when walking on stairs cannot be reduced smoothly.

  Therefore, the characteristic of the stable rotational moment by the mechanical biasing means is variably set according to the roll angle of the roll joint, and in the range where the roll angle is large, the increase of the stable rotational moment becomes dull even if the roll angle increases. By doing so, it becomes possible to efficiently cancel the rotational moment around the roll axis due to the predetermined weight, and thus the amount of power consumed by the roll joint during walking can be suppressed.

  According to the present invention, in a biped walking robot, it is possible to suppress the amount of power consumed by the roll joint of the hip joint during walking.

  Here, an embodiment of a biped robot according to the present invention will be described with reference to the drawings.

  FIG. 1 shows a skeleton diagram of a biped robot (hereinafter simply referred to as “robot”) suitable for application of the present invention. Basically, the skeleton diagram is symmetrical, and only the right leg will be described for the sake of simplicity. Further, the left and right in this embodiment are the left and right as viewed from the robot 001 side shown in the drawing. Therefore, the term “right leg” refers to the left leg toward the paper surface.

  In FIG. 1, the entire leg 002 is fixed to the pelvis 006 by a direction changing joint 004, and a roll joint 008 and a pitch joint 010 are disposed below the pelvis 006. With this arrangement, when the direction changing joint 004 rotates, the entire leg rotates about the yaw axis 005, and when the roll joint 008 rotates, the entire leg swings about the roll axis 009, and the pitch joint 010 further rotates. When moved, the entire leg swings around the pitch axis 011. These three joints are arranged so that their output axes are orthogonal to each other, forming a hip joint.

  Below the hip joint is a knee joint 014 coupled to the thigh link 012, and further below that is an ankle joint coupled to the snelink 016. The ankle joint includes a pitch joint 018 and a roll joint 020 orthogonal thereto. A foot portion 022 that is in contact with the ground is coupled under the ankle joint. Also, there is an upper body portion 024 coupled to the pelvis 006, and the upper body portion includes a torso, an arm, a head, and the like, and the weight closely related to the present invention occupies a considerable amount. However, since the structure itself is not a main constituent factor of the present invention, it is only roughly shown by a two-dot chain line. The positions of the joints are controlled by a drive motor (hereinafter also simply referred to as “motor”) driven by electric energy.

FIG. 2 is a front view of the robot 001 shown in FIG. 1 as seen from the front when the right leg is in a standing state while walking on a flat floor. The robot 001 across the center of gravity at the time of this position and the point P _R. If the mass of the robot 001 and M, Mg vertically downward to the point _{P R} (g is approximately 9.8 m / ^{s 2} acceleration of gravity) force is acting. _'If the point P _R' points vector of this force intersects the ground P _R in should be a force of the same size as the Mg vertically upward as the road surface reaction force.

At this time, the load moment of gravity acting on the roll joint 008 of the hip joint is obtained. The gravitational moment that acts on the roll joint 008 is the weight of the robot 001 excluding the weight of the lower part from the roll joint 008 (specifically, the sum of the weight of the upper body 024 and the left leg that is the free leg). , and the to the center of gravity and the point Q _R. If the posture as shown in FIG. 2, the point Q _R, positioned slightly upper left from the point P _R, assumed to be in the position shown. Mg is exerted vertically downward to the point Q _R. Here, m is the mass M of the entire robot 001 minus the mass below the roll joint 008 of the right leg. In this case the horizontal distance from the roll joint 008 to the point Q _R and X _R, gravitational load moment T _R applied to the roll joint 008 is expressed by the following equation.
T _R = mg × X _R

In the rotation arrows in Figure 2, clockwise, represent the magnitude and direction of gravity load moment T _R. If attempts to keep continuously the attitude, the drive motor of the roll joint 008 is required to output a stable torque T _M of the T _R and counterclockwise equal magnitude. Real robot 001 during walking is not stationary in the illustrated position, since the moving continuously, the calculation of the stabilization torque T _M, it is necessary to consider the amount of inertial force. However, in reality, the rotational moment due to the inertial force is smaller than the gravity load moment, so the presence of the rotational moment due to the inertial force can be ignored. Therefore, for convenience of explanation, a stable torque T _M is the gravitational load moment T _R and the same magnitude, and its direction is opposite.

To issue this stable torque T _M, the drive motor must electric current I which is proportional to the stable torque T _M, the power determined by the product of the current I and the power supply voltage V is consumed. Moreover, the gravity load moment T _R is mainly proportional to the roll angle theta _R legs. The roll angle θ _{R at the} roll joint 008 is relatively small, but since no physical work is performed on the outside, this power is wasted energy consumption.

FIG. 3 is a view of the robot 001 shown in FIG. 1 as seen from the front when the left leg is in a standing state while walking on a flat floor. The position of the center of gravity of the entire robot 001 moves to the right and becomes P _L , and the vertically downward gravity vector Mg now penetrates the ground contact surface of the left leg. In this state, a load moment _TL applied to the roll joint 008 of the right leg hip joint is obtained. At this time, the weight of the lower right leg acts on the roll joint 008, the center of gravity position of the right leg is Q _L, and the horizontal distance from the roll joint 008 to the center of gravity Q _L is X _{When L} is _L and the mass below the roll joint 008 of the right leg is m ′, the load gravity moment _TL applied to the roll joint 008 is expressed by the following equation.
T _L = m′g × X _L

Here, 'since the not applied weight of the upper body portion 024, m' m is sufficiently small compared to m, also sufficiently smaller than the distance X _L also X _R. Gravity load moment T _L from this that is sufficiently small gravitational load moment the gravity load moment T _R. The gravity load moment T _L also is an amount that increases substantially in proportion to the roll angle theta _L of thigh link 012. When this load moment _TL is illustrated, it becomes a counterclockwise rotation arrow as illustrated. The driving motor of the roll joint 008 must output a stable torque T _M in the clockwise direction at the same size as the load moment, it is necessary to supply a current I which is proportional to the moment. The electric power calculated by this current is also useless energy for the above reason.

Here it should be noted, the direction of gravity load moment T _R and T _L applied to the roll joint 008 in FIGS. 2 and 3 become opposite, thus stabilizing torque T _M and vice versa in both their corresponding It is to be oriented. Considering this, a balancer spring corresponding to the mechanical biasing means in the present invention is designed.

The graphical representation of the relationship between the above stable rotational moment T _M and the roll angle theta _R in FIG. Here, the roll angle θ _R is the swing angle of the thigh link 012 from the upright standing posture of the robot 001, and the direction of the rotation angle of the stable rotation moment _TM and the roll θ _R is counterclockwise + and clockwise. Is displayed with-. That right leg increases stable rotational moment T _M with a large percentage of the increase in the roll angle theta _R is (when the theta _R> 0) when the stance phase, when the left leg is standing (theta _{R <0} effected even if, in the case) corresponding to theta _L shown in FIG. 3 stable rotational moment T _M is increased by a small percentage of the increase in the roll angle theta _R (provided that the direction of the stable torque T _M is the stance It will be the opposite of The reason why the rate of increase of the stable rotational moment T _M is small is that _XL and m ′ are sufficiently small as described above.

Next, FIG. 5 shows a basic concept when the present invention is applied. In the figure, the design concept of the balancer spring for the portion where the stable rotational moment _TM is positive will be described. The balancer spring is an elastic member and applies an urging force to the outside by expanding and contracting itself. By now balancer spring moment characteristics with respect to the roll angle theta _R is represented by T _S, a part of the gravitational load moment is supported as shown by a dotted line. In that case, the stable rotation moment T _M should bear the remainder obtained by subtracting the support moment of the balancer spring from the gravity load moment. For example, given the time the roll angle of theta _O, moment should bear the driving motor of the roll joint 008 requires only slightly T _{M0 '.} The line T _M 'in the figure indicates the moment to be borne by the drive motor when supported by the balancer spring.

  6 and 7 show one specific design example of the balancer spring 036. FIG. 7 is an enlarged view around the right leg balancer spring 036 shown in FIG. 6, and FIG. 7 (a) shows a state in which the robot 001 is in the upright standing posture (state shown in FIG. 6). 7 (b) is a diagram in which the robot 001 is in the standing state (for example, the state shown in FIG. 2) as shown in FIG. 2, and FIG. As shown in FIG. 3, the robot 001 is in a state where the right leg is in a free leg state (for example, the state shown in FIG. 3).

  Here, the structure around the balancer spring 036 will be described with reference to FIG. The auxiliary link 030 is extended horizontally from the upper link of the roll joint 008, and the auxiliary link 032 is extended horizontally from the lower link of the roll joint 008 (ie, the thigh link 012). The upper end of the balancer spring 036 is fixed to the auxiliary link 030. Further, a small hole 034 is opened in the auxiliary link 032, and the balancer spring 036 is prevented from coming out by the stopper 038 after the lower end of the balancer spring 036 is passed through the small hole 034. The roll joint 008 is mounted in parallel. In FIG. 6, for the sake of understanding, the dimension of the stopper 038 in the upright standing posture is depicted such that there is a gap with the auxiliary link 032. It is designed to touch.

When the thigh link 012 is swung by the roll joint 008 from this state to the posture shown in FIG. 7B, the distance between the auxiliary link 030 and the auxiliary link 032 becomes longer, and the stopper 038 is in contact with the auxiliary link 032. Thus, the balancer spring 036 is extended. As a result, the left leg including a pelvis 006 against the thigh link 012, to generate a supporting moment to rotate in the direction of the stable torque T _M shown in FIG.

  Conversely, when the thigh link 012 is swung in the posture shown in FIG. 7C, the distance between the auxiliary link 030 and the auxiliary link 032 is shortened, but the lower end of the balancer spring 036 is formed by the small hole 034 of the auxiliary link 032. For this reason, the stopper 038 does not contact the auxiliary link 032. In other words, when the balancer spring 036 is mounted, the small hole 034 and the stopper 038 create a neutral state in which a play portion is provided in the balancer spring 036 and the biasing force is not generated.

Therefore, in the state shown in FIG. 7C, the length of the balancer spring 036 remains natural, and no urging force is generated by the balancer spring 036. In other words, when the roll angle theta _R is negative, the balancer spring 036 is not supporting the gravity load moment, nor to increase the gravitational load moment by the urging force is contracted is balancer spring 036.

In the region where the roll angle theta _R is negative, because the gravity load moment as described above, relatively small compared to the region to be the roll angle theta _R is positive, balancer as shown in FIG. 6, FIG. 7 Even if the elastic effect of the spring 036 is one-sided and the spring is not involved in this negative region, the amount of power consumed by the drive motor of the roll joint 008 can be kept relatively low.

  Further, since the robot 001 is symmetric, attaching a similar balancer spring to the left leg as shown in FIG. 6 allows the left leg to be in the standing phase as shown in FIG. The roll joint can be mechanically supported.

  Here, FIG. 8 shows a more detailed application example of the balancer spring based on the above idea. FIG. 8 is a cross-sectional view in which the leg of the robot 001 is cut along a plane including the yaw axis 005 and the roll axis 009, and is also a VIII-VIII cross section in FIG. The left side of FIG. 8 corresponds to the front of the robot 001 and the right side corresponds to the rear. FIG. 9 is a view taken in the direction of the arrow Z in FIG. 8 and shows the right leg hip joint of the robot 001 as viewed from the front.

  In FIG. 8, a direction changing joint 004 includes a case that houses a harmonic reduction gear, an input shaft 150 that transmits a rotational force input to the reduction gear by a belt from a motor (not shown), and the input is a reduction gear. And an output shaft 154 that is output with increased power via the. The internal structure of such a speed reducer is well known and will not be described in detail. For example, it is assumed that it is the same as that shown by reference numeral 162 in FIG. Connected to the output shaft 154, the entire right leg can rotate about the yaw shaft 005 in the figure.

  A motor 156 for applying roll rotation to the roll joint 008 is installed, and its output is transmitted to the input shaft 160 of the speed reducer 162 via belt pulleys 157 and 158. The rotational force is increased by the reduction gear 162, and the output shaft 164 is rotated around the illustrated roll shaft 009. A thigh link 012 is supported on the output shaft 164 so as to be rotatable around the yaw axis 005, and is fixed so as not to rotate in other directions. That is, when the motor 156 rotates, as a result, the thigh link 012 is configured to perform a rotational motion that is a roll swinging motion of the leg around the roll shaft 009. The swinging motion in the pitch direction occurs around the pitch axis 011 (axis perpendicular to the paper surface), and a motor 180 is provided as a motor that gives the motion. These are also disclosed in FIG.

  Now, a part of the thigh link 012 is provided with a thick part, and a bolt 170 is screwed in using a screw provided in the thick part. The neck of the bolt 170 has a circular cross section so as to accept a retaining hole of a balancer spring 136 described later. Further, an arm 172 corresponding to the auxiliary link 030 shown in FIG. 6 extends horizontally from a part of the case for storing the roll rotation motor 156, and a bolt 174 similar to the bolt 170 is embedded in the arm 172. The neck of the bolt 174 welcomes a stop hole provided at the upper end of the balancer spring 136.

  FIG. 9 shows the details of the balancer spring 136 more clearly. In FIG. 9, the lower end of the balancer spring 136 is bent so as to form an elongated elliptical hole 138, and the neck of the bolt 170 is in contact with the lower end of the elliptical hole. The balancer spring 136 is not fixed to the thigh link 012 by the main part of the bolt 170, and the lower end thereof slides along the shape of the hole 138. That is, the balancer spring 136 is connected to the thigh link 012 with the play portion 138a. The play portion 138a is a range that is not occupied by the balancer spring 136 in the movable range of the lower end of the balancer spring 136. Further, the upper end of the balancer spring 136 is bent so as to form a circular hole, and is fixed to the arm 172 by the neck portion of the bolt 173.

  Here, the state shown in FIGS. 8 and 9 is a view when the robot 001 is in an upright standing state as shown in FIG. The outline of the operation of the balancer spring 136 when the robot 001 walks from the state shown in FIGS. 8 and 9 will be described.

In the upright standing state shown in FIGS. 8 and 9, the balancer spring 136 is in a natural length state. When the thigh link 012 rotates clockwise about the roll shaft 009 from the upright standing state of the robot 001, that is, when the right leg as shown in FIG. 7B or FIG. The balancer spring 136 is extended in contact with the lower end of the hole 138. As a result, a rotational moment that causes the balancer spring 136 to return to the upright standing posture is applied around the roll shaft 009. In other words, stable rotation moment against the gravity load moment generated in the roll axial 009 by right leg is standing state (moment represented by T _R in Fig. 2) is mechanically generated by the balancer spring 136 To do.

Next, when the thigh link 012 rotates counterclockwise around the roll shaft 009 from the upright standing state of the robot 001, that is, when the right leg as shown in FIG. 7C or FIG. The bolt 170 slides in the play area 138 a of the hole 138. At this time, the bolt 170 only slides in the play portion 138a, and does not reach the balancer spring 136. As a result, no rotational moment around the roll axis 009 is generated by the balancer spring 136. In other words, when the right leg is in the free leg state, the balancer spring 136 mechanically generates a rotational moment against the gravity load moment (moment represented by _TL in FIG. 3) generated on the roll shaft 009. Although the rotational moment that promotes the gravity load moment is not generated by the balancer spring 136, the balancer spring 136 is in a neutral state.

  As described above, when the robot 001 walks, paying attention to the right leg, when the right leg is in a standing state, the pelvis 006 above the roll axis 009 is rotated counterclockwise about the roll axis 009. Since the stable rotational moment is exerted by the balancer spring 136, the output torque corresponding to the rotational moment out of the output torque that the driving motor 156 of the roll shaft 009 should exhibit in order to maintain the balance of the robot 001 during walking It becomes unnecessary. As a result, it is necessary to pass a current corresponding to the torque that is no longer needed, and the power consumption is suppressed.

  On the other hand, when the right leg is in the free leg state, the rotation moment against the gravity load moment is not exerted by the balancer spring 136, so the drive motor 156 must exhibit the output torque corresponding to the gravity load moment. . However, since the gravitational load moment when the right leg is in the free leg state is much smaller than the gravitational load moment when the right leg is in the standing state as described above, the current flowing through the drive motor 156 is small. Power consumption is low.

  When the robot 001 is walking, the left leg is in a swinging state when the right leg is in a standing state, and the left leg is in a standing state when the right leg is in a swinging state. By installing it on the leg side, it is possible to suppress the amount of power consumed by the roll joint driving motor by the balancer spring 136 in either the right leg or the left leg.

  FIG. 10 shows a transition of electric power consumed for driving the roll joint 008 when a walking experiment of the walking robot 001 is performed. The horizontal axis in FIG. 10 represents time (robot walking time), and the vertical axis represents consumed power (watts). A line L1 in FIG. 10 shows a transition of power consumption during walking of the robot not provided with the balancer spring 136, and a line L2 represents power consumption during walking of the robot provided with the balancer spring 136. Shows the transition. As described above, the amount of electric power (joule) consumed for driving the roll joint 008 is reduced by about 25% by providing the balancer spring 136.

In the present施例, the roll angle theta _R of thigh link 012 is gradually increased, the position of the bolts 170 that hold the lower end of the balancer spring 136, the roll shaft so as to draw a locus indicated by arcs C1 in FIG. 9 Turn around 009. As a result, the distance between the two bolts 170 and 174 increases with an increase in the roll angle θ _R while the roll angle θ _R is small, but the distance increases as the roll angle θ _R increases. The degree of becomes smaller. That is, in proportion to the increase of the roll angle theta _R, stable rotation moment is not to increase generated by the balancer spring 136 to vary non-linearly.

Here, when the robot 001 walks up and down the stairs, the leg in the standing state is forced to roll greatly, so that the leg in the swinging state from the back without interfering with the leg in the standing state is moved forward. It is necessary to roll the leg in the free leg state larger than when walking on a flat ground. As a result, the even more horizontal distance X _R from the hip shown in Figure 2 to the center of gravity Q _R. However, the distance X _R is not increased in proportion to the increase of the roll angle theta _R. Therefore, by making the increase in the stable rotational moment generated by the balancer spring 136 non-linear as described above, a stable rotational moment that more appropriately resists each of the gravitational load torques generated when walking on flat ground and walking on stairs is generated. It becomes possible to make it. That is, it can be avoided that it is difficult to sufficiently suppress the power consumption of the driving motor 156 due to an excessively small or excessive stable rotational moment generated by the balancer spring 136.

  As clearly shown in FIG. 9, since the lower end of the balancer spring 136 of this embodiment is bent in a loop shape and guided by the neck of the bolt 170, the position of the balancer spring 136 deviates from the designed position during operation. Therefore, it is possible to prevent worries that the characteristics will be lost and to ensure reproducibility.

  In FIG. 9, a motor 192 for driving the knee joint 014 is housed in the thigh link 012, and the output is transmitted to the input shaft of the speed reducer provided at the knee joint 014 via the belt pulley 194. It is shown that. However, since this point is not directly related to the present invention, the description thereof is omitted.

  Based on FIG.11 and FIG.12, the 2nd Example of the bipedal walking robot which concerns on this invention is described. 11 and 12 show a detailed structure around the roll joint of the right leg of the robot 001. FIG. FIG. 11 corresponds to FIG. 8 and is a cross-sectional view of the leg in a plane including the yaw axis 005 and the roll axis 009 around the roll joint 0008, and the left side is the front of the robot 001 and the right side is the same as FIG. It is backward. FIG. 12 is a cross section taken along line XII-XII in FIG. FIG. 12 corresponds to FIG. 9 and is also a front view of the robot 001 viewed from the front as viewed in the direction of arrow Z in FIG.

  In addition, in the method of assigning the reference numbers of the components of the robot 001, only the numbers in the 100th range are set to 2 for comparison with the first embodiment and the numbers of similar components. Moreover, the same reference numerals are given to the same components. Therefore, only major changes will be described in detail for these parts, and parts that are not specifically described are basically the same as those in the first embodiment.

  In FIG. 11, a balancer spring 310 is shown at the left end of the roll shaft 009 of the roll joint 008 of the hip joint. That is, the roll shaft 009 is horizontally extended in the left direction to constitute the spring guide portion 312, and the balancer spring 310 is disposed concentrically with the roll shaft 009 on the outer peripheral portion thereof. The balancer spring 310 is a rotation spring, and the right end is inserted into a first slit 314 provided on the output shaft side of the direction changing joint 004 and is fixed in the rotation direction of the rotation spring. Further, the left end of the balancer spring 310 is inserted into a second slit 316 provided in the spring guide portion 312. In order to prevent the balancer spring 310 from falling off from these slits after assembly, a washer 318 is attached to the left end of the spring guide portion 312 with four bolts. The detailed shape of these two slits will be apparent with reference to FIG.

  In FIG. 12, the description of the drop-off preventing washer 318 is omitted for convenience of explanation. The first slit 314 is processed to have basically the same width as the wire diameter of the balancer spring 310, whereas the second slit 316 allows the balancer spring 310 to freely rotate within a predetermined rotation angle range. It is processed so that it is wider than the wire diameter. That is, the play portion 316a is provided in the second slit 316, and one end of the balancer spring 310 can rotate in the second slit 316 including the play portion 316a.

  The state of the robot shown in FIGS. 11 and 12 is a state when the robot 001 is in the upright standing posture. Here, FIG. 13 shows the operation of the balancer spring 310 when the robot 001 is in the upright standing posture, the right leg is in the standing leg state, and the right leg is in the swinging leg state. , (C) respectively. When the robot 001 is in the upright standing posture, as shown in FIG. 13A, one side 316b of the slit width of the second slit 316 is in a position in contact with one end of the balancer spring 310, and the other side of the slit width. 316c is not in contact at all. Due to this positional relationship, when the robot 001 is in the upright standing posture as shown in FIG. 2 and the right leg is in the standing state, the thigh link 012 is turned from the state shown in FIG. Rotating clockwise, the balancer spring 310 is immediately twisted. The positional relationship between the balancer spring 310 and the second slit 316 at this time is the same as that shown in FIG. 13A, as shown in FIG.

As a result, the balancer spring 310 applies a stable rotational moment around the roll shaft 009 to return to the upright standing state. In other words, stable rotation moment against the gravity load moment generated in the roll axial 009 by right leg is standing state (moment represented by T _R in Fig. 2) is mechanically generated by the balancer spring 310 Will do.

  Next, when the thigh link 012 rotates clockwise about the roll axis 009 from the upright standing state of the robot 001, that is, when the right leg as shown in FIG. As described above, one end of the balancer spring 310 rotates in the play portion 316 a of the second slit 316. At this time, one end of the balancer spring 310 only rotates in the play portion 316a and is in contact with the one side 316b of the slit width of the second slit 316 and one side 316c opposite thereto. Therefore, the balancer spring 310 is not twisted.

As a result, the balancer spring 310 does not generate any rotational moment around the roll axis 009. In other words, when the right leg is in the free leg state, the balancer spring 310 mechanically generates a rotational moment that opposes the gravity load moment (moment represented by _TL in FIG. 3) generated on the roll shaft 009. However, the rotation moment that promotes the gravity load moment is not generated by the balancer spring 310, and the balancer spring 310 is in a neutral state.

  Accordingly, in this embodiment as well, as in the first embodiment, it is possible to support the gravity load torque by the balancer spring 310, and the power consumption of the drive motor 256 of the roll joint 008 when the robot 001 is walking is reduced. It becomes possible to suppress.

One of the features of this embodiment is that the shape of the balancer spring 310 can be designed to be small around the roll shaft 009, and there is little change in the shape during its operation, and other parts of the robot 001 such as wiring It is a point which does not entrain and interfere with things of indefinite shape, such as pipes and pipes. In order to make this feature more prominent, the entire balancer spring 310 may be covered with a plastic cover as shown by a two-dot chain line in FIG.

It is a figure which shows the schematic skeleton figure of the lower half of the biped walking robot which concerns on the Example of this invention. In the biped walking robot according to the embodiment of the present invention, it is a schematic configuration diagram when the right leg is in a standing state. In the biped walking robot according to the embodiment of the present invention, it is a schematic configuration diagram when the right leg is in a free leg state. In the roll joint of the biped walking robot according to the embodiment of the present invention, it is a diagram showing the relationship between the roll angle and the rotational moment that the drive motor should exert against the gravity load moment in order to maintain the balance during walking. is there. It is a figure which shows the relationship between a roll angle and the stable rotation moment which supports a gravity load moment with a mechanical urging | biasing force in the roll joint of the biped walking robot which concerns on the Example of this invention. FIG. 5 is a schematic diagram illustrating a basic concept of supporting a gravity load moment by a spring in a biped robot according to an embodiment of the present invention. FIG. 7 is an enlarged view around the roll joint of the biped walking robot shown in FIG. 6, corresponding to the main posture of the biped walking robot. In the biped walking robot according to the first embodiment of the present invention, it is a first view showing a detailed structure around a balancer spring provided in parallel with a roll joint. In the biped walking robot according to the first embodiment of the present invention, it is a second view showing a detailed structure around the balancer spring provided in parallel with the roll joint. It is a figure which shows transition of the electric power consumed with the drive motor of a roll joint in the bipedal walking robot which concerns on the 1st Example of this invention. In the biped walking robot concerning the 2nd example of the present invention, it is the 1st figure showing the detailed structure of the balancer spring circumference provided in parallel with the roll joint. In the biped walking robot according to the second embodiment of the present invention, it is a second view showing a detailed structure around the balancer spring provided in parallel with the roll joint. In the biped walking robot concerning the 2nd example of the present invention, it is a figure showing roughly the operation of the balancer spring corresponding to the main posture of the biped walking robot.

Explanation of symbols

001 ... Biped walking robot (robot)
002 ... Leg whole 008 ... Roll joint 009 ... Roll shaft 012 ... Thigh link 030 ... Auxiliary link 032 ... Auxiliary link 034 ... Small hole 036・ ・ ・ Balancer spring 038 ・ ・ ・ ・ Stopper 136 ・ ・ ・ ・ Balancer spring 138 ・ ・ ・ ・ Hole 138 a ・ ・ ・ ・ Play area 156 ・ ・ ・ ・ Drive motor 256 ・ ・ ・ ・ Drive motor 310 ・ ・.... Balancer spring 312 ... Spring guide 314 ... First slit 316 ... Second slit 316a ... Play area

Claims (8)

A biped robot that has two legs composed of a plurality of link members and joints that connect each of the link members, and that walks by driving the legs,
Among the joints of the legs, in the hip joint of the hip joint that swings the body of the biped robot about the roll axis, the side opposite to the rotation direction of the rotational moment around the roll axis due to a predetermined weight generated when the biped robot walks A bipedal walking robot comprising mechanical urging means for mechanically generating a stable rotational moment in accordance with a roll angle on the roll axis in parallel with the roll joint. The roll joint is a roll joint of a leg that is in contact with the walking road surface during walking of the biped robot,
2. The biped according to claim 1, wherein the predetermined weight is at least a weight of a leg that is not in contact with a walking road surface and an upper body of the biped walking robot when the biped walking robot is walking. Walking robot.   The mechanical biasing means generates a stable rotational moment about the roll axis in the predetermined rotational direction, and does not generate a stable rotational moment about the roll axis in a direction opposite to the predetermined rotational direction. The biped robot according to claim 2, wherein   The mechanical biasing means generates a stable rotational moment about the roll axis in the predetermined rotational direction, and has a stability smaller than the stable rotational moment in the predetermined rotational direction in a direction opposite to the predetermined rotational direction. The biped robot according to claim 2, wherein a rotational moment is generated. The mechanical biasing means is a spring member,
Both ends of the spring member are respectively connected to the legs at upper and lower portions sandwiching the roll shaft, and at least one end of the spring member is connected to the legs in a state having a play portion within a predetermined range. The biped walking robot according to claim 3 or 4, characterized in that the biped walking robot is characterized. The mechanical biasing means is a rotary spring member,
The rotary spring member has one end connected to the leg and the other end connected to the roll shaft, and at least one of the one end or the other end has a play area in a predetermined range. The biped robot according to claim 3 or 4, wherein the biped robot is connected to a leg.   The bipedal walking robot according to claim 6, wherein a central axis of the rotary spring member is concentric with the roll axis.   2. The mechanical urging means increases the stable rotational moment as the roll angle increases, and decreases the increasing rate of the stable rotational moment as the roll angle increases. The biped walking robot according to claim 7.

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