JP2006159296A - Walking robot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide technology capable of reducing a measuring error of a position and a posture of a trunk even without applying any special reinforcement and minimizing calculating quantity to calculate the position and the posture of the trunk in accordance with output of a gyro sensor in a robot walking while detecting the position and the posture of the trunk by using the gyro sensor. <P>SOLUTION: This robot walks by oscillating more than two leg links. This robot is furnished with a waist to which the more than two leg links are connected free to oscillate, the trunk connected to the waist free to revolve and the gyro sensor arranged on a lower end part of the trunk. A measuring point of the gyro sensor is adjusted at a position on an axis of revolution of the trunk, and the gyro sensor measures an index concerning angular velocity around the axis of revolution of the trunk. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a robot in which two or more leg links are connected so as to be swingable with respect to the waist, and the robot walks by swinging the two or more leg links. In particular, the present invention relates to a walking robot in which a trunk is rotatably connected to a waist. The trunk is rotatable about an axis extending in the longitudinal direction of the trunk and extending in parallel with a line connecting the waist and the head.

  A robot that walks by changing the relative posture of the left leg link and the right leg link with respect to the trunk or waist has been developed. When changing the relative posture of the left leg link and the right leg link with respect to the trunk or waist, the relative posture of the left leg link and the right leg link must be changed so that walking can result. . For this purpose, gait data that indicates the position and posture of the trunk, left toe, and right toe is used.

  As shown in FIG. 5, the gait data indicates the positions and postures of the trunk, left toe, and right toe in a global coordinate system that defines the coordinates of the space in which the robot is active. In order to indicate the positions of the trunk, left toe, and right toe, a reference point W0 is defined for the trunk, a reference point L0 is defined for the left toe, and a reference point R0 is defined for the right toe. It has been established. In order to indicate the posture of the trunk, left toe and right toe, a vector W extending along the trunk is assumed, a vector L perpendicular to the left toe is assumed, and a vector R perpendicular to the right toe Is assumed. The gait data indicates the x, y, z coordinates of the reference point W0 of the trunk, the x, y, z coordinates of the reference point L0 of the left foot tip, and the reference point R0 of the right foot tip in the global coordinate system. The x, y, and z coordinates are designated. Further, the pitch angle Wα of the vector W extending along the trunk, the roll angle Wβ, and the yaw angle Wγ are designated, and the pitch angle Lα, the roll angle Lβ, and the yaw angle Lγ of the vector L perpendicular to the left foot tip are designated. The pitch angle Rα, roll angle Rβ, and yaw angle Rγ of the vector R perpendicular to the right foot tip are instructed. Further, in the case of a robot that walks while twisting (twisting) the trunk with respect to the waist, the pivot angle Wδ of the trunk with respect to the waist is indicated. The gait data stores data indicating the position and posture of the trunk, left foot tip, and right foot tip over time. In the case of a robot that walks while twisting its trunk against the waist, it also stores data that indicates the pivot angle Wδ of the trunk relative to the waist over time.

Given gait data that indicates the position and posture of the trunk, left toe, and right toe, the robot calculates the joint angles of each joint necessary to take the given position and posture, and calculates the calculated joints. Adjust to the corner. Since the gait data changes over time, the joint angle can also change over time. The robot walks by changing the relative postures of the trunk, the left leg link, and the right leg link over time according to the gait data. In the case of a robot that walks while twisting the trunk, the robot walks while changing the rotation angle Wδ of the trunk with respect to the waist according to the gait data. The rotation angle Wδ between the waist and the trunk can be said to be one of data describing the trunk posture with respect to the waist.
Prepare gait data to maintain the position of the trunk (Wx, Wy, Wz) and the posture of the trunk (Wα, Wβ, Wγ, Wδ) in the ZMP (zero moment point) of the robot within the foot of the grounded leg If so, the robot will continue to walk without falling.
The above system can be said to be a system in which all joints of the robot are actively moved to walk, and is described in Patent Document 1 and the like.

The position and posture of the trunk described above are measured in real time while the robot is walking and used for control. The position and posture of the trunk can be calculated from the position of the contact leg and the joint angle of each joint, but the measurement accuracy can be improved by using a gyro sensor.
The gyro sensor detects an index related to the angular velocity, and can process the acceleration to know the angular acceleration and the angle. Patent Document 2 discloses a walking robot that includes a right leg link, a left leg link, and a trunk and has a gyro sensor disposed on the trunk. Patent Document 3 also discloses a walking robot in which a gyro sensor is arranged on the trunk. These walking robots can accurately grasp the position and posture of the trunk.
Japanese Patent Laid-Open No. 05-253867 JP-A-7-205069 Japanese Patent Laid-Open No. 2004-9205

  A gyro sensor may cause measurement errors due to various factors. The measurement error of the gyro sensor causes an error in the posture of the robot that is measured as a result, and thus greatly affects the stable walking of the robot.

  When a gyro sensor is mounted on a portion having low rigidity, the gyro sensor detects a local vibration generated in the portion. Such local vibration has nothing to do with the global behavior of the trunk of the robot and causes measurement errors of the gyro sensor. Conventionally, in order to suppress such a measurement error, reinforcement for securing rigidity is applied to a portion where the gyro sensor is mounted. Such reinforcement is not preferable because it increases the weight of the robot.

  The trunk may vibrate due to the elastic deformation of the leg link or the waist or the rattling of the joint. The vibration generated in the trunk has nothing to do with the global behavior of the trunk and causes a measurement error of the gyro sensor.

  There is a need for a technique that can reduce the measurement error as described above without applying special reinforcement.

The walking robot measures the posture of the trunk and uses the measurement result to adjust the joint angle thereafter. It is preferable that the timing to use the measurement and the measurement result is extremely short, and the time from the output of the gyro sensor to the calculation of the trunk posture is extremely short.
In many cases, the reference point of the trunk is set to the central axis (parallel to the line connecting the waist and the head) extending in the longitudinal direction of the trunk. When the gyro sensor is mounted at a position offset from the central axis as in the robot described in Patent Document 2, many correction calculations are required to calculate the posture of the trunk reference point. Such a correction calculation imposes a large load on a device that controls walking of the robot, and lengthens the time difference between the measurement timing and the timing of using the measurement result. This reduces the walking speed. It is desirable to be able to calculate the data indicating the posture of the trunk reference point from the output of the gyro sensor without performing complicated correction calculation.

  The present invention solves the above problems. In the present invention, in a robot that walks while detecting the position and posture of the trunk using a gyro sensor, measurement errors of the position and posture of the trunk can be reduced without applying special reinforcement, and the gyro sensor Provides a technology that requires less calculation amount to calculate the position and posture of the trunk based on the output of

The robot of the present invention walks by swinging two or more leg links. The robot according to the present invention is arranged at a waist where two or more leg links are swingably connected, a trunk connected so as to be rotatable with respect to the waist, and a lower end of the trunk. It has a gyro sensor.
The measurement point of the gyro sensor is adjusted to a position on the rotation axis of the trunk, and the gyro sensor measures an index related to the angular velocity around the rotation axis of the trunk. The output of the gyro sensor is not particularly limited as long as the angular velocity can be calculated. Any device that outputs a voltage proportional to angular velocity or angular acceleration or outputs a pulse wave at a velocity proportional to angular velocity or angular acceleration is sufficient, and any device that can calculate angular velocity is not particularly limited. As the gyro sensor, a sensor based on any measurement principle may be used, and a mechanical gyro, a vibration gyro, an optical gyro, or the like can be used.

In this robot, two or more leg links are connected to the waist. A trunk is rotatably connected to the waist. This robot walks by driving each joint based on gait data that indicates the positions and postures of the toes and trunk.
In the case of the robot configured as described above, the lower end of the trunk is a joint portion with a joint (hereinafter referred to as a hip joint) that rotatably connects the trunk to the waist. Since the weight and inertial force of components mounted on the upper body of the robot act on the coupling portion, the coupling portion is manufactured with high rigidity using a high-strength member.
By disposing the gyro sensor at the lower end of the trunk having high rigidity, the gyro sensor can be mounted on the part having high rigidity without reinforcement. The influence which the vibration resulting from the elastic deformation of the trunk exerts on the measured value of the gyro sensor can be suppressed.

  Also, the lower end of the trunk has a short distance from the tip of the grounding leg, which is a fulcrum of exercise, when the robot swings up one leg link and uses the other leg link as the grounding leg. Therefore, the amplitude of vibration caused by the robot's ground leg link, elastic deformation of the waist, and rattling at the joint is small. By placing the gyro sensor at the lower end of the trunk where the distance from the toes of the ground leg is short, it is possible to reduce the influence of vibration caused by the ground leg link and elastic deformation of the waist on the measured value of the gyro sensor. it can.

  Further, with the above configuration, the measurement point of the gyro sensor can be arranged on the rotation axis of the trunk. In addition, an index related to the angular velocity around the rotation axis of the trunk can be directly measured by the gyro sensor. Since no offset occurs between the measurement point of the gyro sensor and the rotation axis of the trunk, the posture of the trunk reference point can be calculated by simple calculation.

  According to the present invention, in a robot that walks while detecting a trunk motion using a gyro sensor, a measurement error can be reduced and a calculation amount can be reduced without performing special reinforcement.

  Hereinafter, embodiments embodying the present invention will be described with reference to the drawings.

(First embodiment)
A robot according to the present invention will be described with reference to the drawings.
FIG. 1 shows a skeleton diagram of the mechanical configuration of the robot 30. The robot 30 includes motors 1, 2,... With encoders at each joint, can adjust each joint angle, and can measure each joint angle. The robot 30 has two axes 4, 5, 9, 10 for the ankle joint, one axis 3, 8 for the knee joint, two axes 1, 2, 6, 7 for the hip joint, one axis 24 for the hip joint, and two axes for the shoulder joint. 11, 12, 14, 15, 1 axis 13, 16 at the elbow joint and 3 axis 21, 22, 23 at the neck joint. Reference numerals 17 and 18 indicate force sensors, and 19 and 20 indicate photo sensors. The photosensors 19 and 20 detect whether the foot is grounded or floating. Reference numeral 25 indicates a gyro sensor. The gyro sensor 25 includes a measurement point and a measurement axis. The measurement point of the gyro sensor 25 exists on the rotation axis of the motor 24 of the hip joint. The gyro sensor 25 detects angular velocities around three axes of an orthogonal coordinate system with the rotation axis of the motor 24 of the hip joint as one axis.
The robot 30 includes a controller (not shown). The controller inputs the outputs of the encoders of the joints, the outputs of the force sensors 17 and 18, the outputs of the photo sensors 19 and 20, and the output of the gyro sensor 25. The controller watches the walking status of the robot 30 based on the input from these sensors. Specifically, the controller measures the position and posture of both feet from the output of the encoder of each joint. Further, the position and posture of the trunk reference point are measured from the output of the encoder of each joint and the output of the gyro sensor 25. Based on the walking situation, the controller determines the gait data so that the ZMP of the robot 30 exists within the foot of the grounding leg. The controller calculates the rotation angle of the motor of each joint from the gait data by inverse kinematics calculation. The controller instructs the rotation angle to the motor of each joint.
As described above, the robot 30 walks. Since the ZMP is controlled to exist in the foot of the grounding leg, the robot 30 can walk without falling down.

FIG. 2 is a view showing an overview of the trunk 40 of the robot 30.
The trunk 40 is composed of a box-shaped metal member in which various devices can be mounted. By configuring the trunk 40 with a box-shaped member, rigidity against bending and torsion is ensured, and the trunk 40 can be prevented from being greatly deformed while the robot 30 is walking. Furthermore, by constructing the trunk 40 with a box-shaped member, it is possible to secure a space in which various devices are mounted.

The lower end of the trunk 40 is connected to the lumbar joint motor 24 via a waist fitting 46. The waist fitting 46 is a U-shaped metal member, and has a flange at the tip of the U-shape. The waist fitting 46 has a flange connected to the lower end of the trunk 40 using bolts and nuts. The waist joint motor 24 is mounted on the waist 48 and rotates the trunk 40 via the waist fitting 46. The waist joint motor 24 and the waist fitting 46 constitute a waist joint of the robot 30.
A left leg link 42 and a right leg link 44 are connected to the waist 48. The left leg link 42 includes left hip motors 1 and 2. The right leg link 44 includes motors 6 and 7 for the right hip joint.

  The upper end of the trunk 40 is connected to the shoulder joint including the motors 11 and 14 and the neck joint including the motors 22, 23 and 24 (hidden in FIG. 2) using bolts and nuts. The right shoulder joint realizes the movement of the right arm of the robot 30. The left shoulder joint realizes the operation of the left arm of the robot 30. The neck joint realizes the movement of the head of the robot 30.

  3 and 4 are diagrams schematically showing a joint portion between the trunk 40 and the waist 48. FIG. FIG. 3 is a perspective view of the inside of the trunk 40 when the trunk 40 and the waist 48 are viewed from the front. FIG. 4 is a perspective view of the inside of the trunk 40 when the trunk 40 and the waist 48 are viewed from the left side.

  As shown well in FIGS. 3 and 4, the trunk 40 includes a bottom plate 50, a middle plate 52, and a top plate 54. A waist fitting 46, which is a part of the waist joint, is connected to the bottom plate 50. The waist fitting 46 is intensively loaded with all loads acting on the upper and lower body of the robot 30 during walking. Therefore, a member having high rigidity and high strength is used for the bottom plate 50 to which the waist fitting 46 is connected. In general, a thick plate material is used. A neck joint and a shoulder joint are connected to the top plate 54. A total load acting on the trunk 40 from the head of the robot 30 is intensively applied to the neck joint during walking. A total load acting on the trunk 40 from the arm of the robot 30 during walking is concentrated on the shoulder joint. Therefore, a member having high rigidity and high strength, that is, a member having a large thickness is used for the top plate 54, but a member having a smaller thickness than the bottom plate 50 is used. The intermediate plate 52 supports a device to be mounted inside the trunk 40. In order to suppress the vibration of the device mounted inside, it is preferable that the rigidity of the intermediate plate 52 is high. However, since a large load is not applied to the intermediate plate 52, the thickness of the intermediate plate 52 is not applied to the bottom plate 50 or the top plate 54. Thin compared. As shown in FIG. 3, the trunk 40 includes side plates 56 and 58. The side plates 56 and 58 are subjected to a bending load when bending is applied to the trunk 40 and a shearing load when twisting is applied to the trunk 40. Not. Therefore, the side plates 56 and 58 are thinner than the bottom plate 50 and the top plate 54. As shown in FIG. 4, the trunk 40 includes a front plate 60 and rear plates 62 and 64. Since these members are not loaded with such a large load, the plate thickness is thinner than that of the bottom plate 50.

As shown in FIGS. 3 and 4, the gyro sensor 25 is provided on the bottom plate 50 inside the trunk 40. The gyro sensor 25 is screwed to the bottom plate 50 at a plurality of locations. The gyro sensor 25, the measurement point is to lie on the axis of the rotation axis Z _A of the hip joint, it has been adjusted position.

As shown in FIGS. 3 and 4, the measurement point of the gyro sensor 25 exists on the rotation axis of the waist joint 24. Reference point of the trunk 40, in order to present on rotation axis Z _A of the hip joint, with respect to angular velocity about Z _A-axis, it can be used as an angular velocity measured by the gyro sensor 25. Since there is no offset between the reference point of the trunk 40 and the gyro sensor 25, correction calculation for specifying the angular velocity of the reference point can be eliminated, and the burden of the controller that measures the position and posture of the trunk in real time can be eliminated. Can be reduced.

  Since the bottom plate 50 has high rigidity, even when a disturbance is applied while the robot 30 is walking, no large local vibration is generated. Accordingly, it is possible to prevent a measurement error from occurring in the gyro sensor 25 due to the influence of disturbance.

  The gyro sensor 25 is located at the lowermost part of the trunk 40. When the robot 30 swings up one leg link and grounds the other leg link, the angular velocity is detected at a position close to the toe of the ground leg. can do. Since the angular velocity is detected at a position close to the tip of the ground leg, vibration due to elastic deformation of the ground leg link and the waist 48 and backlash at the hip joint, the hip joint of the ground leg, the knee joint, and the ankle joint are caused. The influence of vibration can be kept small.

As mentioned above, although embodiment of this invention was described in detail, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
In addition, the technical elements described in the present specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

FIG. 1 is a skeleton diagram of a robot 30 according to the present invention. FIG. 2 is a schematic view of the trunk 40 of the robot 30. FIG. 3 is a perspective view of the inside of the trunk 40 of the robot 30 from the front. FIG. 4 is a perspective view of the inside of the trunk 40 of the robot 30 from the side. FIG. 5 is a diagram schematically showing a robot that walks by swinging the right leg link and the left leg link.

Explanation of symbols

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 21, 22, 23, 24 ... motors 17, 18 ... force Sensors 19, 20 ... Photo sensor 25 ... Gyro sensor 30 ... Robot 40 ... Trunk 42 ... Left leg link 44 ... Right leg link 46 ... Waist fitting 48 ... Waist 50 ... Bottom plate 52 ... Plate 54 ... Top plate 56, 58 ... Side plate 60 ... Front plate 62, 64 ... Rear plate

Claims (1)

It is a robot that walks by swinging two or more leg links,
A waist to which two or more leg links are swingably connected;
A trunk that is pivotally connected to the waist;
It has a gyro sensor arranged at the lower end of its trunk,
The measurement point of the gyro sensor is adjusted to a position on the pivot axis of the trunk,
The gyro sensor measures an index related to the angular velocity around the pivot axis of the trunk,
A walking robot characterized by that.

Images