JP4700997B2 - Biped robot - Google Patents

Description

  The present invention relates to a biped walking robot in which an arm is attached to a shoulder joint of a torso and a leg is attached to a hip joint, and in particular, a load that can float or float and acts on an actuator constituting the joint is applied. The present invention relates to a biped robot that has been reduced in weight by a simple configuration.

  The technology related to biped robots is advancing rapidly, and various industries are exploring the possibility of applying them to various needs. Such biped robots are sometimes called humanoid robots. By improving their walking performance and realizing joint movements closer to humans, the intimidation can be reduced and the work content and range can be enhanced / widened. It has been. In Japan, where we are facing an aging society, application to nursing care for the elderly and the disabled is being considered, and facility guidance is provided at expos and amusement facilities, and production lines that manufacture automobiles, home appliances, etc. Plays its role as an assembly robot.

  Looking at the construction industry, the application of biped robots is desired for disaster recovery activities and disaster recovery surveys in the event of frequent earthquakes and typhoons. In addition, in construction and demolition and removal work of various public facilities and office buildings, it is possible to reduce accidents by using biped robots on behalf of humans, especially in highly dangerous work. It will lead to the improvement of social reliability for the construction industry. Considering the decrease in the labor force population, the expectation for a biped robot is even higher.

  Regarding the development of biped walking robots, as disclosed in Patent Documents 1 to 4 of the prior disclosure, the energy of the legs is devoted to realizing not only walking but also running and jumping. Therefore, no development has been made on a biped robot that floats or floats. However, by developing a biped robot that has not only traveling performance but also floating performance, its activity range is wider and application to the work described above becomes more realistic. However, there are descriptions in Patent Documents 5 and 6 regarding a device for floating a person in the air.

  When levitating / floating a biped robot, there are various problems that cannot be solved by simply attaching a flying means such as a known helicopter to the biped robot. For example, the overall weight increases due to the mounting of the flying means, and there is a cascading adverse effect that mounting a walking joint (actuator) that can withstand such an increase in weight further increases the overall weight and scale. . There is also a problem of stability during levitation / floating.

JP 2005-64837 A JP 2004-299035 A JP 2003-266337 A JP 2003-231081 A JP 2004-306668 A JP 2004-268640 A

  The biped walking robot of the present invention has been made in view of the above-described problems, and an object thereof is to provide a biped walking robot that can stably float and float and can perform work in a wide range. It is another object of the present invention to provide a relatively light and small biped robot by suppressing the increase in the weight of the entire robot by providing flying means. Of course, depending on the required work content, it is possible to provide a biped robot that is relatively heavy and large in scale.

  In order to achieve the above object, a biped robot according to the present invention is a biped robot in which an arm is attached to a shoulder joint of a torso and a leg is attached to a hip joint. A propulsion device that floats the robot vertically upward is mounted so as to be tiltable, and can be floated in an appropriate direction by tilting the propulsion device as appropriate.

  Although the embodiment of the biped walking robot is not particularly limited, for example, there is a biped walking robot having the following configuration. First, the shoulder joint is provided with an actuator (servo motor, etc.) for rotating or rotating the arm about two axes, a roll axis and a pitch axis (two degrees of freedom), and the arm attached to the shoulder joint. The upper arm part, the elbow joint, the lower arm part, the wrist joint, and the hand part are connected to each other. When the elbow joint has two degrees of freedom and the wrist joint has two degrees of freedom, the robot has six degrees of freedom in the shoulder joint to the arm portion. The degree of freedom of each joint can be set to an appropriate degree of freedom according to the application work content. The hip joint is equipped with actuators that rotate or rotate the leg about the roll axis, yaw axis, and pitch axis. The leg consists of the thigh, knee, crus, ankle and foot. For example, the knee joint can have one degree of freedom and the ankle joint can have two degrees of freedom. Here, it is needless to say that the biped walking robot may be an embodiment provided with a known leg mechanism capable of not only walking but also running and jumping.

  The biped walking robot of the present invention is equipped with a propulsion device for levitating / floating the biped walking robot. The embodiment of the propulsion device is not particularly limited, and can be configured by, for example, a fan, a balloon, or a combination thereof. For example, one or more fans are tiltably mounted on the back of the body, shoulders, etc., and when the biped robot rises, the fans are tilted in an appropriate direction to float in a desired direction. It has a possible configuration. The weight of the fan is preferably as light as possible. The biped robot is equipped with a gyro sensor or the like for controlling the posture in the air. A configuration that can adjust the thrust is desirable.

  In a preferred embodiment of the biped walking robot according to the present invention, at least three propulsion devices are provided around the torso, and when the biped walking robot floats or floats, The center of gravity of the two-legged walking robot and the resultant force center of the thrusts of the plurality of propulsion devices can be adjusted to be substantially the same in plan view.

  For example, a case where a fan is applied as a propulsion device will be described as an example. In order to ensure the stability of the robot when the robot floats or floats, it is desirable that at least three fans that are radixes that can form a plane be mounted on the robot. For example, three fans are mounted in a horizontal plane around the trunk so that thrust (propulsive force) is generated vertically downward with respect to the biped robot standing upright. As an example, there is a form in which fans are mounted on the left and right shoulders and the back.

  In the present invention, in order to ensure the stability of the biped walking robot when levitating / floating, the center of gravity position of the robot in the basic posture (upright state) when the biped walking robot floats in the air and a plurality of fans It is possible to adjust so that the resultant force centers of the two thrusts coincide or are substantially the same. When each fan tilts so that the biped robot can ascend to a certain altitude and float in an appropriate direction, the sensor detects the change in the center of gravity of the robot, and the thrust of each fan is calculated in plan view. A thrust force that causes the robot to float in a desired direction is applied to each fan while substantially matching the center of resultant force with the detected center of gravity position.

  In order to make the resultant center of the thrust of the fan easily coincide with the center of gravity of the robot in plan view, for example, three or four fans may be arranged in advance in the same plane in the robot in an upright posture. . With respect to the change in the center of gravity of the robot and the change in thrust of each fan when the fan is tilted when floating, it is possible to realize stable floating of the robot only by finely adjusting the thrust of an appropriate fan, for example.

  In a preferred embodiment of the biped robot according to the present invention, when at least the biped robot floats or floats, the propulsion unit is positioned higher than the center of gravity of the biped robot including the propulsion unit. It is characterized by being arranged.

  For example, by setting the height of a plurality of propulsion devices arranged in the same plane to a position higher than the center of gravity of the biped walking robot including the propulsion device, particularly when the biped walking robot floats. Can improve the stability.

  In another embodiment of the biped robot according to the present invention, two propulsion devices out of the at least three propulsion devices are respectively mounted on left and right arms.

  A robot that does not require a hand, for example, a biped walking robot for taking a picture of the situation in a disaster area, has a configuration in which a propulsion unit is mounted under the elbow joint that constitutes the arm. The propulsion device can be tilted by effectively using the joints and elbow joints. In this case, a propulsion device is attached to each of the left and right elbow joints, and another propulsion device is attached to the back of the fuselage at the same level as the propulsion device attached to the arm (form with three propulsion devices) There are forms mounted on the front and back of the fuselage (forms with four propulsion units).

  In another embodiment of the biped robot according to the present invention, the propulsion device is a ducted fan.

  By using a ducted fan with a fan installed in the duct, it is possible to avoid the possibility of interference between the fan and the fuselage when the fan is tilted, or the possibility of airborne obstacles colliding with the fan when the robot is floating. , Can improve the floating safety of the robot.

  In another embodiment of the biped robot according to the present invention, the leg portion is provided with a knee joint and an ankle joint, and the hip joint, the knee joint, and the ankle joint are each composed of an actuator including a motor. The load reducing means for reducing the load acting on the actuator when each joint bends is provided in the vicinity of the actuator.

  When a propulsion device such as a ducted fan is attached to a biped robot, the overall weight of the robot increases. Due to the increase in weight, for example, the knee joint of the leg increases the load acting on the joint when the leg is bent around the joint, so the characteristics and scale of the actuators that make up the knee joint are enhanced. / There is a need to increase the scale. By increasing the scale of the actuator, the overall weight increases, and it becomes necessary to change the scale of the propulsion unit to meet this weight increase. The scale will increase in a spiral manner. In order to solve such a problem, in the present invention, a load reducing means for reducing a load due to an increase in weight is provided at a knee joint, an ankle joint, and a hip joint connecting the leg and the trunk. When each joint is composed of a servo motor, etc., the member connected to the joint bends about the motor drive shaft, and when trying to return to the original posture from this bent posture, the torque in the direction opposite to that at the time of bending (Restoring force torque) is required. As the overall weight of the robot increases, it is necessary to increase the performance or increase the scale because it is necessary to increase the restoring force torque performance of the joints of the legs and the crotch. Therefore, for example, by providing an appropriate load reducing means in the vicinity of the actuator that applies a torque in the direction opposite to the rotational torque of the servo motor that acts at the time of bending the joint, the scale of the actuator is not increased. It is possible to obtain a restoring force torque that can withstand an increase in weight.

  Further, in another embodiment of the biped robot according to the present invention, the load reducing means comprises a tension spring straddling between members bending around an actuator constituting each joint, and when the two members are bent. It is characterized in that a restoring force torque in a direction opposite to the load torque acting on the actuator acts on the actuator.

  In the present invention, a tension spring is used as a load reducing means mounted near the actuator, and a coil spring, a leaf spring, or the like can be used. For example, when applying the tension spring to the knee joint, the tension spring is arranged in front of the knee joint so as to connect the upper member (thigh) and lower member (lower leg) of the actuator that constitutes the knee joint. By doing so, the tension spring can apply a torque in the direction opposite to the bending direction to the actuator that is to be restored after being bent.

  Further, in another embodiment of the biped robot according to the present invention, an auxiliary member extending toward the other member is attached to one or both members bent around the actuator. The auxiliary member and the other member or the auxiliary members are connected by a tension spring, whereby a relatively large restoring force torque is obtained by relatively shortening the length of the tension spring.

  The restoring force torque is determined by the product of the tensile force acting on the tension spring and the torque radius from the actuator center to the tensile force acting line. In the present invention, for example, a tension spring between the auxiliary member and the other member is mounted on one of the two members bent about the actuator by attaching an auxiliary member extending toward the other member. Therefore, the restoring force torque is improved by increasing the tensile rigidity of the spring.

  Furthermore, in another embodiment of the biped walking robot according to the present invention, in the biped walking robot, the separation force between the tension spring and the actuator is made as long as possible so that the tensile force acting on the separation and the tension spring is increased. The restoring force torque consisting of

  In the present invention, for example, the restoring force torque is increased by effectively extending the auxiliary member attached to one member to the other member side. As described above, the restoring force torque is calculated from the product of the tension force acting on the tension spring and the torque radius. Here, simply shortening the spring length of the tension spring only increases the tension rigidity of the spring, and even if the tension force increases, it does not effectively increase the restoring force torque value. Therefore, the extension direction of the auxiliary member attached to one or both of the members that bend around the actuator constituting the joint is extended to the other member side, and the distance from the actuator center is as long as possible. By doing so, the restoring force torque can be effectively increased. As one example, there is a configuration in which one end of an auxiliary member formed in an L shape is fixed to one member, and the other end of the auxiliary member and another member are connected by a tension spring.

  As can be understood from the above description, according to the biped walking robot of the present invention, a plurality of propulsion devices such as ducted fans can be attached to the robot so that the biped walking robot can stably float and float. The biped walking robot having both the biped walking performance and the flight can be obtained. In addition, according to the biped robot of the present invention, even when the overall weight of the robot is increased by mounting the propulsion device, the restoring force torque is appropriately generated in the vicinity of the actuators constituting the hip joints and the leg joints. By mounting the load reducing means, it is not necessary to increase the performance / scale of the actuator, and thus a lightweight and small biped robot can be obtained.

  Embodiments of the present invention will be described below with reference to the drawings. 1 is a front view showing the structure of the biped walking robot, FIG. 2 is a side view showing the structure of the biped walking robot, and FIG. 3 is a view taken along the arrow III-III in FIG. ing. FIG. 4 is a schematic diagram showing an embodiment of the load reducing means, where (a) shows a state before the joint is bent, and (b) shows a state when the joint is bent. FIG. 5 is a schematic view showing another embodiment of the load reducing means, where (a) shows a state before the joint is bent, and (b) is when the joint is bent. Each of the figures showing the state is shown. 6 is a side view showing a situation where the biped walking robot is levitating forward, FIG. 7 is a side view showing a situation where the biped walking robot is levitating backward, and FIG. FIG. 9 is a front view showing a situation where the biped walking robot is levitating in the right direction, and FIG. 9 is a side view showing a situation where the biped walking robot is levitating while rotating in the left direction. . FIG. 10 is a side view showing a situation where the leg is bent around the knee joint of the biped walking robot, and FIG. 11 shows a situation where the biped walking robot is supporting one leg during walking. Front views are shown respectively. It should be noted that the degree of freedom (the number of actuators) constituting each joint is not limited to the illustrated embodiment, and the number of propulsion units (ducted fans) and their arrangement positions are also limited to the illustrated embodiment. Of course, it is not a thing.

  FIG. 1 is a front view showing an embodiment of a biped robot, and FIG. 2 is a side view thereof. The biped robot 1 includes left and right upper arm members 4 and 4 connected to the body 2 and shoulder joints 3 and 3, left and right leg portions 6 and 6 connected to the hip joints 5 and 5, and tips of the upper arms 4 and 4 and the body 2. Are substantially composed of ducted fans 7, 7, 7 and a head 92 respectively mounted on the rear surface of the head. For example, a CCD camera (not shown) is mounted on the head 92.

  The shoulder joint 3 links an actuator 31 that rotates the upper arm 4 around the pitch axis (in the direction of arrow X1 in FIG. 1) and an actuator 32 that rotates the upper arm 4 around the roll axis (in the direction of arrow X2 in FIG. 1). The members 33 are connected to each other. Here, the actuator 31 is embedded in the body 2. The upper arm member 4 is fixed to one side surface of the actuator 32, and a ducted fan 7 that is a propulsion device is attached to the upper arm member 4. The inclination of the ducted fan 7 can be adjusted by rotating or rotating the actuators 31 and 32.

  Further, the leg portion 6 can be rotated in the direction of the arrow Y1 by the actuator 51 constituting the hip joint 5, and this is a movement when the whole weight is moved to only one leg portion during walking. A separate actuator 52 is provided below the actuator 51, and the leg portion 6 can be rotated back and forth around this actuator 52 (in the direction of arrow Y2). An auxiliary member 82 is fixed to the body 2, and a tension spring 81 connects the end of the auxiliary member 82 and the protrusion 82 a near the actuator 52. The thigh member 61 has one end connected to the actuator 52 and the other end connected to the actuator 62 constituting the knee joint. Here, as shown in FIG. 2, the actuator 62 constituting the knee joint is rotatably connected to the actuator 64 constituting the ankle joint across the lower leg member 63 (see FIG. 1). The actuator 64 constituting the ankle joint is capable of rotating about the pitch axis of the foot member 66, and the actuator 65 is an actuator capable of rotating about the roll axis of the foot member 66. Here, one end of the auxiliary member 84 formed in a substantially L shape from the link member 63 a that connects the actuators 62 and 64 is fixed, and one end of the tension spring 83 is fixed to the auxiliary member 84. The other end of the tension spring 83 is fixed to the end portion of the protruding portion 61b from the link member 61a that connects the actuators 52 and 62 via the engaging portion 84a at the end portion.

  As shown in FIG. 2, an auxiliary member 86 is fixed to the actuator 64 constituting the ankle joint, and the end of the auxiliary member 86 and the actuator 62 are connected by a tension spring 85.

  Next, the configuration of the ducted fan 7 will be described with reference to FIG. In the ducted fan 7, a plurality of fans 71, 71,... Are rotatably supported around a rotation shaft inside a cylindrical duct 72, and arranged below the fan 71 in the circumferential direction at intervals. A plurality of rectifying plates 73, 73,... Are mounted. The ducted fan 7 can be rotated by a motor 74 shown in FIGS. By attaching the ducted fan 7 to the biped walking robot 1 as a propulsion device, the danger that the fan interferes with the robot body can be avoided.

  Next, the operation of the load reducing means will be described with reference to FIGS. In the biped walking robot 1 described above, the load reducing means is composed of tension springs 81, 83, 85 and auxiliary members 82, 84, 86 mounted around the joints. FIG. 4 shows an embodiment of load reducing means without an auxiliary member, and FIG. 5 shows an embodiment of load reducing means having an auxiliary member.

  FIG. 4a shows a state before bending of the load reducing means to which the tension spring c is mounted so as to straddle the members a1 and a2 that are bent around the actuator b. FIG. 4b shows a state when the members a1 and a2 are bent. When the member a1 is bent relative to the member a2 in the X1 direction, a tensile force t acts on the tension spring c, and this tension is applied. A restoring force torque consisting of the product of the force t and the torque radius h acts in the X2 direction. Even if the tension force is increased by increasing the spring stiffness of the tension spring, it is difficult to expect a large restoring force torque because the torque radius is small (in the illustrated embodiment, the rotation radius of the output shaft of the actuator).

  On the other hand, FIG. 5a shows the state before bending of the load reducing means in which the auxiliary member d formed in the L shape is attached to the member a2, and the end of the auxiliary member d and the member a1 are connected by the tension spring c. Is shown. When the L-shaped auxiliary member d extends in the direction of the other member a1, the spring length of the tension spring c is shortened. Therefore, the spring rigidity is increased and the tensile force acting on the tension spring c is also increased. In addition, as is apparent from FIG. 5b, when the member a1 is bent in the X1 direction relative to the member a2 around the actuator b, the torque radius h between the tension spring c and the center of the actuator b. 4 is much longer than that in the embodiment of FIG. 4, and as a result, the value of the restoring force torque acting in the X2 direction is also significantly increased. In the biped walking robot 1 of the present invention, the load reducing means shown in FIG. 5 is mounted around the actuators 51, 62, and 64 constituting the hip joint, knee joint, and ankle joint. .., 7,..., Even if the robot weight increases, the load on the actuator is reduced by providing a load reducing means.

  FIG. 6 is a side view showing a situation where the biped walking robot 1 is levitating forward. By rotating the actuator 31 embedded in the body 2 by a predetermined angle X1, the ducted fans 7 and 7 mounted on the left and right arms are rotated in the X2 direction, and floated forward by the thrust of the fan.

  On the other hand, FIG. 7 is a side view showing a situation where the air is levitating backward, and the ducted fans 7 and 7 can be rotated forward (X direction) and levitated rearward by the thrust of the fan. During such ascending and floating, the gyro sensor 91 detects the equilibrium stability and the floating direction of the robot, and the ducted fan 7 at the rear of the fuselage 2 can be floated in a desired direction while ensuring stability. The thrusts and inclination angles of all ducted fans 7, 7, 7 including the thrust are finely adjusted.

  FIG. 8 shows a situation in which the biped robot 1 is laterally moving to the upper right. In this case, the actuators 32 and 32 constituting the left and right shoulder joints 3 and 3 are rotated in the X1 direction, respectively. The lateral movement is made possible by moving the ducted fan 7 in the X2 direction.

  FIG. 9 shows a situation where the biped robot 1 is turning while surfacing. For this turning, the left and right actuators 31 are rotated in opposite directions (front-rear direction), for example, the left ducted fan 7 is rotated in the X1 direction and the right ducted fan 7 is rotated in the X2 direction by the same amount. Can turn clockwise.

  FIG. 10 shows a situation where the biped walking robot 1 bends the leg 6 around the knee joint and the ankle joint. A load torque in the X1 direction acts on the actuator 62 constituting the knee joint, and a tensile force t1 acts on the tension spring 83 against the load torque, and the tension force t1 and a torque radius h1 are included. A restoring force torque acts in the X2 direction. The load torque in the X1 direction is a product of the weight W of the biped walking robot above the knee joint and the action length L from the center of gravity to the knee joint. On the other hand, a load torque in the X3 direction acts on the actuator 64 constituting the ankle joint, and a tensile force t2 acts on the tension spring 85 against the load torque, and the tensile force t2 and the torque radius h2 The restoring force torque consisting of acts in the X4 direction. The load torque can be reduced by the restoring force torque acting around each of the actuators 62 and 65, and it becomes possible to prevent the actuator from becoming higher performance / large scale.

  FIG. 11 shows a situation where the full weight is temporarily supported by one leg when the biped walking robot 1 walks. In the figure, the entire weight is supported by the left foot when the right foot is stepped forward. At this time, a load torque in the X1 direction acts on the actuator 51 constituting the hip joint. A tensile force t acts on the tension spring 81 with respect to the load torque, and a restoring force torque composed of the tensile force t and the torque radius h can be applied in the reverse direction (X2 direction). During walking and running, the left and right arms (including the ducted fan 7) are appropriately rotated as well as the joints of the legs 6 to ensure stability during walking and running. Can do. In this walking stability, the rotation of each joint is controlled based on the detection result by the gyro sensor 91.

  The applicability of the biped robot of the present invention to the robot currently entered in the contest about the biped robot is shown below.

  The weight of the biped robot excluding the propulsion unit is about 20N, and the weight of the three ducted fans is about 15N. The weight of the ducted fan includes a brushless DC motor, a battery, an amplifier, and the like that are rotating machines.

  It is said that a stationary thrust of about 1.3 times the total weight is necessary for the floating of the biped walking robot. Therefore, a thrust of (20N + 15N) × 1.3 = 45.5N is required. Since it is sufficiently possible to expect about 15N as the thrust performance per ducted fan, a small and lightweight biped robot that can float and float can be manufactured sufficiently.

  Next, the effect of reducing the load torque acting on the actuator by the tension spring will be examined. For example, when W shown in FIG. 10 is about 30 N and L is about 100 mm, the load torque acting on the knee joint is 3000 Nmm. The maximum torque of a commercially available servo motor applied to such a small-scale robot is about 3000 Nmm (at 7.4 V), which is the same value as the load torque. Here, it is possible to adjust the rigidity of the tension spring and the shape of the auxiliary member so that the load torque is, for example, about 1500 Nmm, which is half, and it can be used as an actuator by attaching appropriate load reducing means. The motor rating can also be reduced, leading to a reduction in robot manufacturing costs.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

The front view which showed the structure of the biped walking robot. The side view which showed the structure of the biped walking robot. The III-III arrow line view of FIG. It is the schematic diagram which showed one Embodiment of the load reduction means, (a) is the figure which showed the state before a joint bends. (B) is a diagram showing a state when the joint is bent. It is the schematic diagram which showed other embodiment of the load reduction means, (a) is the figure which showed the state before a joint bends. (B) is a diagram showing a state when the joint is bent. The side view which showed the condition where the biped walking robot has surfaced ahead. The side view which showed the condition where the biped walking robot is levitating back. The front view which showed the condition where the biped walking robot has surfaced in the right direction. The side view which showed the condition where the biped walking robot is levitating while rotating to the left. The side view which showed the condition where the leg part is bent centering on a knee joint with a biped walking robot. The front view which showed the condition which the biped walking robot is supporting one leg at the time of a walk.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Biped walking robot, 2 ... Torso, 3 ... Shoulder joint, 31, 32 ... Actuator, 33 ... Link member, 4 ... Upper arm member, 5 ... Hip joint, 51, 52 ... Actuator, 6 ... Leg part, 61 ... Thigh Member, 62 ... Actuator, 63 ... Lower leg member, 64, 65 ... Actuator, 66 ... Foot member, 7 ... Ducted fan, 71 ... Fan, 72 ... Duct, 73 ... Current plate, 81, 83, 85 ... Tension spring, 82, 84, 86 ... auxiliary member, 91 ... gyro sensor, 92 ... head

Claims (8)

In a biped robot in which an arm is attached to a shoulder joint of a torso and a leg is attached to a hip joint,
Around the fuselage, at least three or more propulsion devices are provided,
Of the at least three propulsion units, two propulsion units are respectively attached to the left and right arms,
A biped walking robot that can float in an appropriate direction by rotating the left and right arms to appropriately tilt the two propulsion devices.   When the biped robot floats or floats, the center of gravity of the biped robot including the propulsion unit and the resultant force center of the thrusts of the plural propulsion units are substantially the same in plan view. The biped robot according to claim 1, wherein thrust can be adjusted.   The at least one biped walking robot floats or floats, and the propulsion device is disposed at a position higher than the center of gravity of the biped walking robot including the propulsion device. 2. A biped robot according to 2.   The biped walking robot according to claim 1, wherein the propulsion device is a ducted fan. The leg is provided with a knee joint and an ankle joint,
The hip joint, knee joint and ankle joint are each composed of actuators including motors,
The biped walking robot according to any one of claims 1 to 4, wherein load reducing means for reducing a load acting on the actuator when each joint bends is provided in the vicinity of the actuator. The load reducing means is composed of a tension spring straddling between members that bend around an actuator constituting each joint,
6. The biped walking robot according to claim 5, wherein a restoring force torque in a direction opposite to a load torque acting on the actuator is applied when the two members are bent. An auxiliary member extending to the other member side is attached to one or both members that bend around the actuator.
The auxiliary member and the other member or the auxiliary members are connected by a tension spring, whereby a relatively large restoring force torque is obtained by relatively shortening the length of the tension spring. 6. A biped robot according to 6. The biped robot according to claim 7,
A biped walking robot characterized by further increasing a restoring force torque comprising the separation and a tensile force acting on the tension spring by making the distance between the tension spring and the actuator as long as possible.

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