KR20180004397A - Walking robot and method for controlling balancing the same - Google Patents

Abstract

The present invention proposes a walking robot and a posture control method thereof for controlling a stable posture of the walking robot of which each joint operates using a torque servo. Using the center of gravity of the robot and the inclination and direction of an upper body and a pelvis, the present invention is able to stably maintain the upright posture and a desired angle of the upper body regardless of an external change including any force applied from the outside, an inclination degree of the ground, and the like. Further, even when information about the inclination direction and the inclination degree of the ground is not given to the robot, the present invention is able to maintain the upright posture with respect to the direction of gravity, and even when a standing surface is tilted slowly, an angle of an ankle joint is changed accordingly, such that the upper body and legs can maintain the constant posture.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a walking robot,

The present invention relates to a walking robot for stable posture control of a walking robot in which each joint is operated by a torque servo, and a posture control method thereof.

Research and development of robots that coexist with human beings in a human work and living space with a human-like joint system and are walking are actively proceeding. The walking robot is composed of a multi-legged walking robot having two or more legs or three or more legs, and actuators such as an electric motor and a hydraulic motor located at each joint must be driven for stable walking. The driving method of the actuator is based on a position-based ZMP (zero moment point) control method in which a command angle of each joint, that is, a command position is given and controlled, and a command torque of each joint is given And a torque-based finite state machine (FSM) control method for controlling tracking.

The ZMP control method is based on a ZMP constraint, that is, a safety zone in a supporting polygon composed of bridges supported by the ZMP (within the convex polygon including the area of the foot when supporting with one foot, The walking width, the walking speed, and the like are preliminarily set so as to satisfy the condition that the vehicle should be present in a predetermined area in consideration of safety, and a walking pattern of each leg corresponding to this setting is generated, The walking trajectory of each leg is calculated according to the pattern. In addition, the angle of each joint is computed by inverse kinematics calculation of the calculated gait trajectory, and the target control value of each joint is calculated based on the current angle and the target angle of each joint. And is implemented through servo control that allows each leg to follow the calculated gait trajectory at every control time. That is, it is possible to detect whether the position of each leg exactly follows the walking trace according to the walking pattern, and control the torque of the motor when each leg departs from the walking trajectory, to be.

However, since the ZMP control method is a position-based control method, precise position control can be performed, whereas accurate angle control of each joint is required to control the ZMP, so a high servo gain is required. Because of this, high current is required, which results in low energy efficiency and high rigidity of the joints, which can greatly affect the environment. In order to calculate the angle of each joint, the kinematic singularity should be avoided, so that the knee is always bent while walking, resulting in unnatural walking.

We propose a walking robot and its attitude control method which stably maintain the upper body angle which is able to maintain upright posture and balancing even with the action of external force or the change of slope of the ground.

To this end, one aspect of the present invention provides a hip joint comprising: an upper body; a pelvis link connected to the lower side of the upper body; a plurality of hip joints connected to the lower side of the pelvis link; a plurality of legs respectively connected to the plurality of hip joints; A method of controlling a posture of a walking robot, the method comprising: calculating a position of a current center of gravity of the robot; Setting a position of the target center of gravity of the robot; Calculate an error between the position of the set target center of gravity and the calculated position of the center of gravity; Calculating a force to be compensated for balancing the robot using the calculated center-of-gravity error; Distributing the calculated compensating force to the plurality of legs; Calculating a joint torque of each leg according to the distributed compensation force; The torque servo control is performed using the calculated joint torque. The force that must be compensated for balancing the robot is calculated as follows. When there is a virtual spring between the calculated position of the current center of gravity and the center of the set target center of gravity, It is expressed as the product of the spring constant and the calculated center-of-gravity error.

Further, the position of the center of gravity of the target is set at a position perpendicular to the ground at a midpoint between a plurality of feet brought into contact with the ground.

Further, the position of the target center of gravity is set at a position perpendicular to the ground at any point in a plurality of feet contacting the ground.

And distributing the calculated compensating force to the plurality of legs is calculated by calculating a ratio of a distance between a point where the center of gravity of the robot is projected on the ground and a plurality of feet; Using the calculated distance ratio, the bridge near the point where the center of gravity of the robot is projected on the ground has a larger value.

Measuring the actual rotation angle of the flywheel link; Calculating an error between the measured actual rotation angle and the target rotation angle; And calculating a moment to be compensated for balancing the robot using the calculated rotational angle error, wherein calculating the joint torque calculates a joint torque to produce the calculated compensation moment and the calculated compensating force do.

The actual rotational angle of the flywheel link can be measured by measuring the yaw direction (rotation around the Z axis), the pitch direction (rotation about the Y axis), the roll direction (about the X axis) Rotation) is measured.

The method further includes calculating a gravity compensation torque for each leg, wherein calculating the joint torque compensates for the joint torque of each leg calculated using the gravity compensation torque.

Also, the gravity compensation torque is calculated from the angle q of all foot joints, the position of the mass and center of gravity of all links belonging to each leg, and the total mass and center of gravity of the upper body.

In order to calculate the gravity compensation torque for each leg, gravity compensation is performed in consideration of the weight of the upper body according to the force distributed to the plurality of legs.

In order to calculate the gravity compensation torque for each leg, gravity compensation is performed in consideration of the weight of the opposite leg according to a plurality of leg conditions.

The plurality of legs are separated into a state of supporting the upper body or a state of swinging according to whether or not the feet provided on the respective legs are in contact with the ground.

The method further includes calculating damping torque for each leg, and calculating the joint torque compensates for the joint torque of each leg calculated using the damping torque.

According to an aspect of the present invention, there is provided a hip joint comprising: an upper body; a pelvis link connected to the lower side of the upper body; a plurality of hip joints connected to the lower side of the Felis link; a plurality of legs respectively connected to the plurality of hip joints; A walking robot comprising a foot, comprising: a calculation unit for calculating a position of a current center of gravity of the robot; A setting unit for setting a position of the center of gravity of the target of the robot; Calculating an error between the position of the set target center of gravity and the calculated position of the current center of gravity, calculating a force to be compensated for balancing the robot using the calculated center-of-gravity error, And calculates a joint torque of each leg according to the distributed compensation force; And a servo control unit for performing torque servo control by transmitting the calculated joint torque to the joints of the respective legs. The force to be compensated for balancing the robot is determined by calculating the position of the calculated current center of gravity, When there is a virtual spring between the positions, it is expressed as the product of the virtual spring constant and the calculated center-of-gravity error.

The posture control unit calculates the ratio of the distance between the point where the center of gravity of the robot is projected on the ground and the plurality of feet by using the calculated distance ratio so that the center of gravity of the robot is closer to the point To the plurality of legs.

And further comprising an IMU for measuring an actual rotation angle of the flywheel, wherein the posture control unit calculates an error between the measured actual rotation angle and the target rotation angle, and balances the robot using the calculated rotation angle error Calculate the moment to be compensated for.

Further, the posture control section calculates the joint moment to generate the calculated compensation force and the joint torque to control the posture of each leg.

Also, the posture control unit controls the pitch direction (pitch, rotation around the Y axis), the yaw direction (yaw, Z axis) of the flywheel link due to tilting of the trunk using the IMU, And the actual rotation angle of the rotation around the axis of rotation.

Further, the posture control section calculates the gravity compensation torque for each leg, and compensates for the joint torque of each leg using the calculated gravity compensation torque.

Further, the posture control section calculates the damping torque for each leg, and compensates for the joint torque of each leg using the calculated damping torque.

According to the proposed walking robot and its posture control method, by using the center of gravity of the robot and the rotation angle of the hip joint, it is possible to actively cope with external changes including external force or inclination of the ground, It is possible to stably maintain the upper body angle capable of balancing maintenance.

In addition, the robot can maintain the upright postures in the direction of the gravity of the earth even if no information is given about the flat surface and the slope, and the upper body and the legs change while actively changing the angle of the ankle joint even when the standing surface is gradually inclined It is also possible to maintain the posture without.

In addition, when maintaining the posture of the upper body and the leg, it is possible to position the center of gravity of the robot in the middle of the foot, and if the center of gravity of the robot is positioned on one side of the foot, Is also possible in the same way. This change is possible in real time.

Also, when the target height (Z component) of the center of gravity of the robot is reduced, the joint torque of the hip, knee, and ankle changes, and as a result, the angle of the joint changes so that the upper body can be lowered to the target height in real time.

In addition, if the target rotation angle (roll, pitch, yaw) of the flywheel link is set to all zeros, it becomes a straight line posture, and if it is set to any other value, it is possible to sway in any direction. Particularly when changing the yaw value, the pelvis can be twisted about the vertical axis. This change is possible in real time.

In addition, when an external force is given, it has stiffness that corresponds to the defined spring constant, and if it is continuously pushed, balancing function is performed even if it is in front of or behind the foot like a person. As a result, it became possible to stand still without increasing the strength of the existing method.

1 is an external view of a robot according to an embodiment of the present invention.
Fig. 2 is a view showing a main joint structure of the robot shown in Fig. 1. Fig.
FIG. 3 is a block diagram of a posture control of a robot according to an embodiment of the present invention.
4 is a perspective view illustrating a link structure of a robot according to an embodiment of the present invention.
5 is a front view showing a link configuration of a robot according to an embodiment of the present invention.
6 is a flowchart illustrating a method of controlling a posture of a walking robot according to an embodiment of the present invention.

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

FIG. 1 is an external view of a robot according to an embodiment of the present invention, and FIG. 2 is a view showing a main joint structure of the robot shown in FIG.

1 and 2, a robot 100 is a bipedal walking robot that moves upright by two legs 110 like a human being and includes an upper body 101 made up of a body 102, a head 104, and an arm 106 And a lower body 103 made up of two legs 110. As shown in Fig.

The upper body 101 of the robot 100 includes a body 102, a head 104 connected to the upper part of the body 102 through a neck 120, shoulders 114L and 114R on both sides of the upper side of the body 102, And arms 108L and 108R connected to the ends of the two arms 106L and 106R, respectively.

The body 102 of the robot 100 is provided with a waist joint part 15 having one degree of freedom in the yaw direction so that the body 101 can rotate.

The lower body 103 of the robot 100 includes a pelvis link 16 connected to the lower side of the waist joint 15, two legs 110L and 110R connected to both sides of the lower side of the pelvis link 16, And legs 112L and 112R connected to the ends of the legs 110L and 110R, respectively.

Reference characters "R" and "L" denote the right and left sides of the robot 100, respectively, and a center of gravity (COG) indicates the center of gravity of the robot 100.

A head 41 of the robot 100 is provided with a camera 41 for photographing the surroundings and a microphone 42 for inputting a user's voice.

The head 104 is connected to the body 102 of the upper body 101 through the neck joint 280. The neck joint part 280 is composed of a rotary joint 281 of yaw (Z-axis rotation), a rotary joint 282 of pitch (Y-axis rotation), and a rotation And has three degrees of freedom including joints 283.

Motors (e.g., electric motors, actuators such as hydraulic motors) for rotating the head 104 are connected to the respective rotary joints 281, 282 and 283 of the neck joint 280.

The two arms 106L and 106R of the robot 100 each have an upper link 31, a lower link 32 and a hand 33. [

The upper link 31 is connected to the upper body 101 through the shoulder joints 250L and 250R and the upper link 31 and the upper link 32 are connected to each other via the elbow joint 260. The upper link 31 And the hand 33 are connected to each other through the wrist joint part 270.

The shoulder joints 250L and 250R are provided on both sides of the body 102 of the upper body 101 and connect the two arms 106L and 106R to the body 102 of the upper body 101. [

The elbow joint portion 260 has two degrees of freedom including a pitch joint 261 and a joint joint 262 in the yaw direction.

The wrist joint portion 270 has two degrees of freedom including a pitch joint 271 and a roll joint 272. [

The hand 33 is provided with five fingers 33a. A plurality of joints (not shown) driven by a motor may be installed in each of the hands 33a. The finger 33a performs various operations such as grasping an object in conjunction with movement of the arm 106 or pointing to a specific direction.

A pelvis link 16 having two hip joints 210 is connected to the lower side of the body 102. The pelvis link 16 is a portion corresponding to a human pelvis and is connected to the body 102 of the upper body 101 through the hip joint 210. The IMU 17 detects the relative angle of the Pelvis link 16 with respect to the gravitational direction and the inertial system and detects the relative angle of the Pelvis link 16 with respect to the roll direction, (Pitch, Y axis rotation), and yaw direction (yaw, Z axis rotation).

The two legs 110L and 110R of the robot 100 have the femoral link 21, the lower link 22 and the feet 112L and 112R, respectively.

The femoral link 21 is connected to the felvis link 16 through the hip joint 210 as a portion corresponding to the human thigh and the femoral link 21 and the lower link 22 are connected to the knee joint And the lower link 22 and the feet 112L and 112R are connected to each other through the ankle joint part 230. [

The hip joint part 210 includes a rotary joint 211 (heap yaw joint) in the yaw direction (rotation around the Z axis) and a rotary joint 212 (heap pitch joint in the pitch direction, rotation around the Y axis) And a rotation joint 213 (a hip roll joint) in the roll direction (rotation around the X axis).

The knee joint 220 has a degree of freedom including a rotation joint 221 in the pitch direction.

The ankle joint part 230 has two degrees of freedom including a pitch joint 231 and a roll joint 232.

Since each of the two legs 110L and 110R has six revolute joints for the hip joint 210, the knee joint 220 and the ankle joint 230, twelve legs 110L and 110R are twelve A rotating joint is provided.

On the other hand, a multi-axis F / T sensor (Multi-Axis Force and Torque Sensor) 24 is installed between the feet 112L and 112R and the ankle joint 230 in the two legs 110L and 110R. The F / T sensor 24 measures the three directional components Fx, Fy and Fz of the force transmitted from the feet 112L and 112R and the three directional components Mx, My and Mz of the moment, And the loads applied to the feet 112L and 112R are detected.

Although not shown in the drawing, the robot 100 is provided with an actuator such as a motor for driving the rotating joints. The posture control unit for controlling the overall operation of the robot 100 can realize various operations of the robot 100 by properly controlling the motor.

The robot 100 calculates a torque command for each joint according to each control action for execution of a control action and outputs the calculated torque command to an actuator such as a motor provided in each joint And drives the actuator.

In an embodiment of the present invention, the force and moment to be compensated for real-time balancing of the robot 100 are calculated using the center of gravity position of the robot 100 and the angle of the Pellbiss link 16 viewed from the inertial system . Then, the calculated compensating force and the compensating moment are distributed to the two legs 110L and 110R to calculate the joint torque for controlling the posture of each leg 110L and 110R, and the calculated joint torque is used to calculate the two legs 110L, and 110R. Accordingly, since the joint torque maintains the angle of the upper body 101 stably, it is possible to maintain the upright posture and the balancing of the robot 100. In addition, a portion for compensating for the torque due to gravity is added to each of the legs 110L, 110R so that the center of gravity is prevented from falling down due to gravity. Since the relative inclination of the IMU 17 with the robot 100 in the gravitational direction can be known, the torque of the ankle joint part 230 is controlled actively, regardless of the direction of the ground, , 110R) can maintain the unchanged attitude. This will be described in detail with reference to FIG.

4 is a perspective view illustrating a link structure of a robot according to an embodiment of the present invention, and FIG. 5 is a perspective view of a robot according to an embodiment of the present invention. Fig. 2 is a front view showing a link configuration of the robot.

3, the posture control system of the robot 100 according to an embodiment of the present invention includes a sensor unit 300, a setting unit 310, a posture control unit 320, a servo control unit 330, and two legs 110L, 110R of the hip joint 210, the knee joint 220, and the ankle joint 230, respectively.

The sensor unit 300 measures the slope and the rotation angle of the flywheel 16 in the roll direction (X axis rotation), the pitch direction (pitch, Y axis rotation), the yaw direction (yaw, Z axis rotation) And an F / T sensor 24 installed between the foot 112 of the robot 100 and the ankle joint 230 to detect whether the foot 112 is in contact with the ground.

Tilt detection, gyro sensor, etc. may be used in addition to the IMU 17 as a sensor for detecting the attitude of the body 101. An F / T sensor 24 ), A contact sensor or a corresponding sensor can be used.

The setting unit 310 sets the robot 100 in a position perpendicular to the ground at a midpoint between the two feet 110L and 110R that are in contact with the ground so that the robot 100 can balance in real time while maintaining the upright posture. The position of the target center of gravity COG C '(x, y, z) of the robot 100 is set so that the state of the robot 100 (X, y, z) corresponding to the target center of gravity COG (State).

The posture control unit 320 controls the posture of the robot 100 based on the target center of gravity COG of the robot 100 set by the setting unit 310 and the sensor information detected from the sensor unit 300, A center-of-gravity error calculator 322, a compensation-force calculator 323, a leg distributor 324, a rotation angle error calculator 324, And includes a calculation unit 325, a compensation moment calculation unit 326, first and second torque calculation units 327 and 328, and a torque compensation unit 329.

The center of gravity calculation unit 321 calculates the position of the current center of gravity COG C (x, y, z) of the robot 100 by the IMU 17 and Forward Kinematics. The position of the current center of gravity C (x, y, z) of the robot 100 is provided in the body 102 as shown in FIG. 4. At this time, the current center of gravity COG (x, y , z) depends on the orientation of the inertial system fixed in the direction of gravity.

The center-of-gravity error calculator 322 calculates an error e between the calculated position of the current center of gravity COG C (x, y, z) and the center of the set target center of gravity COG (x, y, z) As shown in the following equation (1).

[Equation 1]

e = C ' -C

The compensation force calculation unit 323 calculates the compensation force calculation unit 323 between the position of the calculated current center of gravity COG C (x, y, z) and the center of the set target center of gravity COG (x, y, z) 105 (constant k _p) force f (f _x, f _y, which must be compensated in order to balance the mobile robot 100 by using the center of gravity error e calculated in the, center of gravity error computation section 322 when there is , f _z ) is calculated as shown in the following equation (2).

&Quot; (2) "

Bridge distributor 324 distributes to as a compensated force f (f _x, f _y, f _z) calculated using the weight center of the error e and Equation 3 below, the two legs (110L, 110R) .

&Quot; (3) "

,

,

In Equation (3), w _L , w _R is using, the center of gravity (COG) of the robot 100 is projected to the ground point and feet distance ratio between (112L, 112R) d _L, d _R, as shown in Figure 5 the robot 100 (For example, 110L) from the point at which the center of gravity COG of the target object is projected on the ground has a larger value as shown in the following Equation (4).

&Quot; (4) "

,

,

The rotation angle error calculator 325 calculates the rotation angle error of the Pelvis link 16 measured by the IMU 17 in the roll direction, the pitch direction and the yaw direction, And calculates the error e ₁ between the rotation angle and the target rotation angle.

The compensation moment calculation section 326 calculates a compensation moment based on the three axes of the roll direction (roll, X axis rotation), the pitch direction (pitch, Y axis rotation), and the yaw direction A moment M (M _x , m) to be compensated for balancing the robot 100 using the rotation angle error e ₁ calculated by the rotation angle error calculator 325, assuming that the spring (constant k ₁ ) M _y , M _z ) are calculated as shown in the following equation (5).

&Quot; (5) "

The first and second torque calculation units 327 and 328 calculate the compensation moment M calculated in the compensation moment calculation unit 326 and the joint torque tau to generate the compensation force f calculated in the compensation force calculation unit 323 For each of the legs 110L and 110R, as shown in the following Equation (6).

&Quot; (6) "

In Equation (6), the joint torque tau is a 6-vector.

와 오른쪽 다리(110R)의 토크

에 대해 동일한 과정을 거치므로 이하에서는 τ라고 설명한다.The torque compensating unit 329 adds the torque G (q) for gravity compensation to the joint torque? Obtained in the equation (6) to calculate the compensated joint torque? ₁ as shown in the following equation (7). At this time, the joint torque? Is the torque of the left leg 110L

And the torque of the right leg 110R

Since the same process is performed for?, It is described as? In the following.

&Quot; (7) "

In Equation (7), G (q) represents the angle q of all the foot joints, the position of the mass and the center of gravity of all the links 21 and 22 belonging to each of the legs 110R and 110L, Mass and center of gravity.

Further, the torque compensating unit 329 adds damping (corresponding to the speed in proportion to the torque) dw to each joint in order to realize stability of the system by implementing the passivity of the system, so that the compensated joint torque? ₂ is calculated.

&Quot; (8) "

In Equation (8), d is a properly set damping coefficient, and w is a measured joint angular velocity.

The servo control unit 330 provides the joint torque τ ₂ finally compensated in the torque compensating unit 329 to the hip joint part 210, the knee joint part 220 and the ankle joint part 230 of the two legs 110L and 110R, respectively A torque control signal corresponding to the compensated joint torque? ₂ to drive an actuator such as a motor installed in the hip joint 210, the knee joint 220 and the ankle joint 230 is transmitted to the hip joint 210, 220 and the ankle joint part 230, respectively.

Accordingly, the hip joint 210, the knee joint 220, and the ankle joint 230 receive the torque control signal from the servo controller 330, and receive the torque control signal from the hip joint 210, the knee joint 220, and the ankle joint 230, By driving an actuator such as an installed motor, the robot 100 can maintain a balance in real time while maintaining an upright posture even if the ground surface is inclined.

Hereinafter, the operation process and effect of the walking robot and the attitude control method constructed as above will be described.

6 is a flowchart illustrating a method of controlling a posture of a walking robot according to an embodiment of the present invention.

In FIG. 6, a user command for instructing the control of the attitude of the robot 100 is inputted through a user interface (400).

The IMU 17 provided on the pelvis link 16 of the robot 100 moves the inclination and direction of the upper body 101 including the pelvis and the body 102 to the roll direction Axis, the X-axis rotation), the pitch direction (pitch, Y-axis rotation), and the yaw direction (yaw, Z-axis rotation) to transmit to the center of gravity calculation unit 321 of the posture control unit 320 (402) .

The center of gravity calculation unit 321 calculates the position of the current center of gravity COG C (x, y, z) of the robot 100 by the IMU 17 and Forward Kinematics, To the error calculator 322 (404).

The setting unit 310 sets the target center of gravity COG of the robot 100 to a position perpendicular to the ground at a midpoint between the two feet 110L and 110R of the robot 100 contacting the ground, y, z) to the center-of-gravity error calculator 322 (406).

Accordingly, the center-of-gravity error calculator 322 calculates the center-of-gravity error by using the position of the current center of gravity COG (x, y, z) calculated by the center-of-gravity calculator 321, (X, y, z) as shown in Equation (1) below, and transmits it to the compensation force calculator 323 (408).

[Equation 1]

e = C ' -C

The compensation force calculation unit 323 calculates a force f (f _x , f _y , f _z ) to be compensated for balancing the robot 100 using the center-of-gravity error e calculated by the center-of-gravity error calculation unit 322, To the leg distribution unit 324, as shown in the following equation (2).

&Quot; (2) "

Accordingly, the bridge minutes to distribute 324 the center of gravity error e compensated force f (f _x, f _y, f _z) of Equation 3, the two legs (110L, 110R), as shown in the following calculation using the (410).

&Quot; (3) "

,

,

In Equation (3), w _L , w _R is using, the center of gravity (COG) of the robot 100 is projected to the ground point and feet distance ratio between (112L, 112R) d _L, d _R, as shown in Figure 5 the robot 100 (For example, 110L) from the point at which the center of gravity COG of the target object is projected on the ground has a larger value as shown in the following Equation (4).

&Quot; (4) "

,

,

The rotation angle error calculator 325 calculates the rotation angle error of the Pelvis link 16 measured by the IMU 17 in the roll direction, the X axis direction, the pitch direction and the yaw direction, calculating a rotation angle and the error e ₁ of the target rotation angle of the Z-axis rotation), and transmits the calculated moment compensation section 326 (412).

Accordingly, the compensation moment calculation unit 326 calculates moments M (M _x , M _y , M _y ) to be compensated for balancing the robot 100 using the rotation angle error e ₁ calculated by the rotation angle error calculation unit 324, M _z ) is calculated as shown in Equation (5) below (414).

&Quot; (5) "

The foot 112 is referred to as the base link of the robot 100 and the center of gravity COG is referred to as the 6-by-6 Jacobian ) ≪ / RTI > Jacobian is a matrix that can translate the velocity of joint space into the velocity of the workspace and is derived from forward kinematics.

The first and second torque calculation units 327 and 328 calculate the compensation moment M calculated by the compensation moment calculation unit 326 and the joint torque? (416) with respect to the two legs 110L and 110R as shown in the following Equation (6).

&Quot; (6) "

In Equation (6), the joint torque tau is a 6-vector.

와 오른쪽 다리(110R)의 토크

에 대해 동일한 과정을 거치므로 이하에서는 τ라고 설명한다.Next, the torque compensating section 329 adds the torque G (q) for gravity compensation to the joint torque? Obtained in the equation (6) to calculate the compensated joint torque? ₁ as shown in the following equation (7) do. At this time, the joint torque? Is the torque of the left leg 110L

And the torque of the right leg 110R

Since the same process is performed for?, It is described as? In the following.

&Quot; (7) "

In Equation (7), G (q) is the sum of the angles q of all the foot joints, the positions of the masses and the centers of gravity of all the links 21 and 22 belonging to the respective legs 110R and 110L and the total mass of the body 101 And the center of gravity position.

In addition, the torque compensating unit 329 adds damping (corresponding to the speed in proportion to the torque) dw to each joint in order to improve the stability of the system by implementing passivity of the system, so that the compensated joint torque? ₂ (418).

&Quot; (8) "

In Equation (8), d is the damping coefficient, and w is the joint angular velocity.

The servo control unit 330 then outputs the joint torque τ ₂ finally compensated in the torque compensating unit 329 to the hip joint part 210, the knee joint part 220 and the ankle joint part 230 of the two legs 110L and 110R The robot 100 is driven in an upright position while maintaining the upright position even if the ground is inclined (420) by driving an actuator such as a motor installed in the hip joint 210, the knee joint 220 and the ankle joint 230, Keep balance.

Therefore, the robot 100 can be balanced even when the angle of the ground is not horizontal, and both the robot 100 and the robot 100 can be balanced when moving slowly or rapidly.

Even if the ground surface is inclined, since the balance of the robot 100 is maintained by using the joints of the two legs 110L and 110R supporting the body 102, the method is simple and a robot having joints of six degrees of freedom 100).

16: Pelvis Link 17: IMU
100: robot 101: upper body
102: body 110L, 110R: leg
112L, 112R: Foot 210: Hip Joint
220: knee joint 230: ankle joint
300: sensor unit 310: setting unit
320: attitude control unit 321:
322: center-of-gravity error calculation unit 323:
324: leg distribution portion 325: rotation angle error calculation section
326: Compensation moment calculation unit 327, 328: Torque calculation unit
329: Torque compensating unit 330: Servo control unit

Claims (19)

A plurality of leg joints connected to a lower side of the Felis link, a plurality of legs respectively connected to the plurality of hip joint parts, and legs respectively provided to the legs, A method of controlling a posture of a walking robot,
Calculating a position of the current center of gravity of the robot;
Setting a position of the target center of gravity of the robot;
Calculating an error between the set target center of gravity position and the calculated current center of gravity position;
Calculating a force to be compensated for balancing the robot using the calculated center-of-gravity error;
Distributing the calculated compensating force to the plurality of legs;
Calculate a joint torque of each leg according to the distributed compensation force;
Performing torque servo control using the calculated joint torque,
A force to be compensated for balancing the robot is calculated by calculating a difference between a constant of the virtual spring and a calculated center-of-gravity error when there is a virtual spring between the calculated current center of gravity and the center of the set target center of gravity, Of the posture of the robot. The method according to claim 1,
The position of the center of gravity of the target,
And setting a position perpendicular to the ground at a midpoint between the plurality of feet in contact with the ground. The method according to claim 1,
The position of the center of gravity of the target,
And setting a position perpendicular to the ground at an arbitrary point in the plurality of feet in contact with the ground. The method according to claim 2 or 3,
And distributing the calculated compensating force to the plurality of legs,
Calculating a ratio of a distance between a point where the center of gravity of the robot is projected on the ground and the plurality of feet;
And a leg near the point where the center of gravity of the robot is projected on the ground surface has a larger value using the calculated distance ratio. The method according to claim 1,
Measuring an actual rotation angle of the flywheel link;
Calculating an error between the measured actual rotation angle and the target rotation angle;
Further comprising calculating a moment to be compensated for balancing the robot using the calculated rotation angle error,
Calculating the joint torque,
And calculating the calculated compensation moment and the joint torque for generating the calculated compensation force. 6. The method of claim 5,
Measuring the actual rotation angle of the flywheel link may include:
The posture control of the walking robot that measures the yaw direction (rotation around the Z axis), the pitch direction (rotation around the Y axis) and the roll direction (rotation around the X axis) with respect to the tilt of the body using the IMU Way. 6. The method of claim 5,
Further comprising calculating a gravity compensation torque for each leg,
Calculating the joint torque,
And compensates for the calculated joint torque of each leg by using the gravity compensation torque. 8. The method of claim 7,
Wherein the gravity compensation torque is calculated from the angle q of all the foot joints, the positions of the mass and the center of gravity of all links belonging to each leg, the total mass of the upper body and the position of the center of gravity. 8. The method of claim 7,
Calculating the gravity compensation torque for each leg,
And performing gravity compensation in consideration of the weight of the upper body according to a force distributed to the plurality of legs. 8. The method of claim 7,
Calculating the gravity compensation torque for each leg,
And performing gravity compensation in consideration of the weight of the opposite leg according to the plurality of leg states. 11. The method of claim 10,
Wherein the plurality of legs are separated into a state supporting the upper body or a state swinging according to whether or not the feet provided on the respective legs are in contact with the ground. 8. The method of claim 7,
Further comprising calculating a damping torque for each leg,
Calculating the joint torque,
Wherein the calculated joint torque of each leg is compensated using the damping torque. A plurality of leg joints connected to a lower side of the Felis link, a plurality of legs respectively connected to the plurality of hip joint parts, and legs respectively provided to the legs, In the walking robot,
A calculation unit for calculating a position of the current center of gravity of the robot;
A setting unit for setting a position of a center of gravity of the robot;
Calculating an error between a position of the set target center of gravity and a position of the calculated current center of gravity, calculating a force to be compensated for balancing the robot using the calculated center-of-gravity error, A posture control unit for distributing a force to the plurality of legs and calculating a joint torque of each leg according to the distributed compensation force; And
And a servo control unit for performing torque servo control by transmitting the calculated joint torque to the joints of the legs,
A force to be compensated for balancing the robot is calculated by calculating a difference between a constant of the virtual spring and a calculated center-of-gravity error when there is a virtual spring between the calculated current center of gravity and the center of the set target center of gravity, Of the walking robot. 14. The method of claim 13,
The posture control unit,
Calculating a ratio of a distance between a point at which the center of gravity of the robot is projected on the ground and a distance between the plurality of feet and calculating a distance between the point at which the center of gravity of the robot is projected on the ground and a bridge Wherein the compensating force is distributed to the plurality of legs. 14. The method of claim 13,
Further comprising an IMU measuring an actual rotation angle of the flywheel link,
The posture control unit,
Calculates an error between the measured actual rotation angle and a target rotation angle and calculates a moment to be compensated for balancing the robot using the calculated rotation angle error. 16. The method of claim 15,
The posture control unit,
And calculates the joint torque to generate the calculated compensation moment and the calculated compensation force to control the posture of each leg. 16. The method of claim 15,
The posture control unit,
(Roll, rotation around the X axis), pitch direction (pitch, rotation about the Y axis), the yaw direction (yaw, rotation about the Z axis) by the tilting of the trunk by the IMU ) To measure the actual rotation angle of the robot. 16. The method of claim 15,
Wherein the posture control unit calculates a gravity compensation torque for each of the legs and compensates for the joint torque of each leg using the calculated gravity compensation torque. 19. The method of claim 18,
Wherein the posture control unit calculates a damping torque for each leg and compensates for the joint torque of each leg using the calculated damping torque.

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