JP2006321012A - Robot and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a robot capable of stabilizing the motion by suppressing the sway of a body trunk resulting from the motion of an upper limb with a simple motion. <P>SOLUTION: At first, joint angles of both arm parts of the robot are acquired (S1). That is, the joint angle of a gripping arm and that of a non-gripping arm are respectively acquired. Next, a distortion of the gravity center position of the upper body is acquired from the joint angles. Then, a correction angle of the non-gripping arm is acquired on the basis of the distortion of the gravity center position of the upper body (S3). That is, a joint angle of the non-gripping arm is acquired so as to allow the gravity center of the upper body to move on the target gravity center position. The joint of the non-gripping arm is minutely displaced according to the correction angle (S4). The gravity center position of the upper body can be always maintained on the target gravity center position by repeating the above steps. Consequently, it is possible to stabilize the walking motion. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a robot in which an upper limb is swingably connected to a trunk. More specifically, the present invention relates to a robot that suppresses the swinging of the trunk caused by the movement of the upper limb and stabilizes the movement.

  Conventionally, walking robots that walk while moving their upper limbs have been disclosed. In this type of robot, the movement of each limb is generally realized by a plurality of actuators. As a method for changing the posture of the robot, for example, gait data that indicates each position of the trunk, left toe, right toe, left hand, and right hand in time series is created, and according to the gait data, The relative postures of the trunk, both legs, and both arms are changed over time (for example, Patent Document 1). That is, each actuator is operated so as to follow the foot and hand trajectories stored in advance.

  The trunk of the robot is provided with a sensor group for detecting the posture angle and acceleration of the trunk. Each joint of the robot is equipped with a motor with an encoder. With these sensors, it is possible to measure the posture of the robot and the position of the center of gravity of the upper body. Usually, gait data is created so that the center of gravity of the upper body is always within a predetermined range (for example, the distance from the center of the trunk is within 10 mm), and the actuators of each joint are controlled according to the gait data. ing.

Even if the walking robot performs a walking motion according to the gait data, the posture may become unstable due to disturbances such as obstacles on the road surface. Thus, for example, a robot is disclosed that estimates the position of the center of gravity from the inclination angle in the absolute coordinates of the foot and controls each joint angle so that the position of the center of gravity becomes the target position of the center of gravity (for example, Patent Document 2).
JP-A-2005-7496 JP-A-5-305580

  However, the conventional robot described above has the following problems. In other words, depending on the movement of the upper limb of the robot, the center of gravity of the upper body may be displaced and walking may become unstable. For example, when the robot grips a load with one upper limb, the position of the center of gravity of the upper body shifts to the upper limb side that holds the load. Also, if the robot carries a load with a bag like a carrying bag, the center of gravity of the upper body shifts backward. For this reason, the balance of the upper body is lost and the walking motion becomes unstable.

  In addition, if the balance is lost due to the upper body movement, the exact center of gravity position cannot be estimated from the inclination angle of the foot. In other words, the center of gravity can be displaced when the foot is horizontal, so the exact center of gravity cannot be determined.

  In addition, when the center of gravity shifts to one upper limb side, it is conceivable to return the center of gravity to a predetermined position by operating the trunk, such as twisting the trunk of the robot to the opposite side. However, during walking movement, if the trunk is twisted, walking movement becomes unstable. In addition, the operation of twisting the trunk itself is complicated and difficult to control.

  The present invention has been made to solve the problems of the conventional robot described above. That is, the problem is to provide a robot that stabilizes the motion by suppressing the trunk shake caused by the motion of the upper limb with a simple motion.

  The robot made for the purpose of solving this problem is a robot having an upper limb whose one end is connected to the trunk, and a center-of-gravity position acquisition unit that acquires the center-of-gravity position of the upper body including the trunk of the robot; A target position storage unit that stores a target position of the center of gravity of the upper body of the robot, a center of gravity that calculates a deviation amount between the target position stored in the target position storage unit and the center of gravity position acquired by the center of gravity position acquisition unit A deviation amount calculation unit and a drive unit that drives the upper limb so that the deviation amount calculated by the gravity center deviation amount acquisition unit is a predetermined value or less are provided.

  That is, the robot of the present invention acquires the center of gravity position of the upper body of the robot by the center of gravity position acquisition unit (center of gravity position acquisition step), and the amount of deviation between the center of gravity position of the upper body and the target center of gravity position by the center of gravity displacement acquisition unit. Acquisition (gravity center deviation acquisition step). The target center-of-gravity position here corresponds to, for example, the position of the center of gravity when standing upright without gripping a load. In addition, the robot can be applied to any position where a good balance can be maintained for the upper body of the robot. The target center-of-gravity position is stored in advance in the target target position storage unit. The position of the center of gravity of the upper body can be calculated based on the joint angle of each joint of the upper body. Alternatively, it is possible to prepare a database in which the position of the center of gravity corresponding to the joint angle of each joint portion is stored, and obtain each joint angle and the weight of the load from the database as parameters.

  Then, the upper limb is driven (driving step) so that the shift amount of the center of gravity is equal to or less than a predetermined value by the driving unit. In other words, the center of gravity of the upper body of the robot is moved by moving the upper limb, and the center of gravity is moved closer to the target center of gravity. The joint angle of each joint necessary for driving the upper limb may be obtained by calculation according to the shift amount of the center of gravity, or may be obtained from a database. As a result, even if a disturbance such as gripping or scooping a load with the upper limb occurs, the center of gravity position of the upper body can always be placed at the target center of gravity position. Therefore, the operation is stable. Furthermore, the center of gravity is controlled only by the movement of the upper limbs. That is, the operation is stabilized by a simple operation for adjusting the posture of the upper limb.

  Further, the upper limb of the robot of the present invention preferably has one or more joints, and the drive unit may move the joints to move the position of the center of gravity. In other words, the movement of the center of gravity can be determined more precisely by moving the joint of the upper limb.

  Further, the robot of the present invention preferably has two or more upper limbs, and the driving unit preferably drives at least one of the upper limbs to move the position of the center of gravity. That is, the movement of the center of gravity can be determined more precisely by selectively moving an appropriate upper limb.

  In addition, the other end of the upper limb of the robot of the present invention has a structure capable of gripping a load, and when the load is gripped by at least one upper limb, the upper limb not gripping the load is detected. It is better to move the position of the center of gravity by operating.

  That is, when the upper limb holding the load is moved, the trunk shakes greatly, and the walking movement is likely to be disturbed. Therefore, only the upper limb not holding the load is operated. In other words, the robot is balanced only by the movement of the upper limb not holding the load. As a result, the walking motion can be more reliably stabilized with a simpler motion.

  According to the present invention, when the gravity center position of the upper body of the robot deviates from a predetermined target gravity center position, the gravity center position is returned to the target gravity center position by operating only the upper limbs. Therefore, a robot has been realized that stabilizes the movement by suppressing movement of the trunk caused by the movement of the upper limb with a simple movement.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying a robot according to the present invention will be described below with reference to the drawings. In the present embodiment, the present invention is applied to a biped walking robot capable of walking while holding a load with an upper limb.

  The walking robot of this embodiment is a biped walking robot including a trunk (trunk), a head, two legs (lower limbs), and two arms (upper limbs). FIG. 1 shows the configuration of each joint in the walking robot 100 of this embodiment. In FIG. 1, the x-axis means the front-rear direction (traveling direction) of the walking robot 100, the y-axis means the left-right direction of the walking robot 100, and the z-axis means the up-down direction (height direction) of the walking robot 100. . The walking robot 100 has two axes for the left and right hip joints, one axis for the waist, one axis for the left and right knee joints, two axes for the left and right ankle joints, two axes for the left and right shoulder joints, and two axes for the left and right elbow joints. Each has one axis of freedom. Each joint is equipped with a motor with an encoder, which can measure the joint angle and adjust the joint angle.

  Specifically, the waist is constituted by the central joint 17 and the left and right joints (hip joints) 1, 2, 6 and 7. Further, the joint (knee joint) 3 is connected to the joint 2 via the thigh link, and the joints (ankle joints) 4 and 5 are connected to the joint 3 via the lower leg link to constitute the left leg, A foot 19 is provided below 5. The joint (knee joint) 8 is connected to the joint 7 via the thigh link, and the joints (ankle joints) 9 and 10 are connected to the joint 8 via the crus link to form the right leg, A foot portion 20 is provided below 10.

  The joint 17 at the center of the waist is connected to the head 18 via a link. Further, joints (shoulder joints) 11, 12, 14, and 15 are connected to a link that is orthogonal to the link connected to the head 18. The joint (elbow joint) 13 is connected to the joints 11 and 12 via the upper arm link, and the joint 13 is connected to the hand part 21 via the forearm link to constitute the left arm part. Further, a joint (elbow joint) 16 is connected to the joints 14 and 15 via the upper arm link, and further, the joint 16 is connected to the hand part 22 via the forearm link to constitute a right arm part.

  At the center of the waist, a posture control sensor group 25 including an acceleration sensor that detects the acceleration of the trunk and a gyro sensor that detects a posture angle (tilt with respect to the z-axis direction) is provided.

  Next, the operation control of the walking robot 100 of this embodiment will be described. As shown in FIG. 2, the walking robot 100 creates gait data for instructing the robot's operation (for example, walking operation, operation for grasping a load, and operation for raising the load at a high position). An instruction generation device 30, a joint angle group calculation device 41 that adjusts the joint angle of each joint, an actuator control device 42 that operates each joint according to the calculated joint angle, and a center of gravity that calculates a minute displacement amount of the center of gravity of the upper body And a position displacement amount calculation device 44.

  The motion instruction generation device 30 has a function of creating gait data that is the basis of motion. The motion instruction generation device 30 includes a toe position command value generation unit 31, a trunk position command value generation unit 32, a hand position command value generation unit 33, and a gait data storage unit 34. The operation instruction generation device 30 receives an operation selection signal and a start / stop signal. Further, from the motion instruction generation device 30, information on the foot tip position and the hand tip position, that is, gait data is output to the joint angle group calculation device 41. Based on this output information, the robot mechanical system is driven.

  The foot position command value generation unit 31 stores a foot path. That is, footstep trajectory data with time indicating the relationship between the three-dimensional coordinates (x, y, z) of both feet and the time is stored in advance. Then, based on the foot tip trajectory data, a command value Rfs (t) for the position of the right foot tip and a command value Lfs (t) for the position of the left foot tip are created. The command values Rfs (t) and Lfs (t) are data indicating the relationship between the toe positions Rfs and Lfs and time t, that is, data in which the contents of the change in the toe position over time are stored. The command values Rfs (t) and Lfs (t) are output to the trunk position command value generation unit 32 and the gait data storage unit 34.

  The trunk position command value generation unit 32 calculates a target ZMP (zero moment point) position based on the toe position information (command values Rfs, Lfs). The target ZMP position is calculated so that it is always within the foot of the grounded foot. The target ZMP position is expressed by two-dimensional coordinates (x, y), and the z coordinate is set to zero. Then, ZMP trajectory data in which the content of the change with time of the target ZMP position is stored is created. Then, a command value W (t) of the trunk reference position is created so that the gait robot 100 operates according to the ZMP trajectory data. The command value W (t) is data indicating the relationship between the trunk reference position W and time t, that is, data in which the content of the change in the reference position with time is stored. The command value W (t) is output to the gait data storage unit 34.

  Details of the method for calculating the command value W (t) are described in Japanese Patent Application No. 2003-171967 or Japanese Patent Application No. 2003-354866 filed by the present applicant.

  The hand position command value generation unit 33 stores the hand trajectory. That is, hand trajectory data with time indicating the relationship between the three-dimensional coordinates (x, y, z) of both hands and time is stored in advance. Based on the hand trajectory data, a command value Rhs (t) for the position of the right hand and a command value Lhs (t) for the position of the left hand are created. The command values Rhs (t) and Lhs (t) are data indicating the relationship between the hand positions Rhs and Lhs and the time t, that is, data in which the contents of the change in the hand position with time are stored. The command values Rhs (t) and Lhs (t) are output to the gait data storage unit 34.

  In addition, a correction angle of the upper limb is sent to the hand position command value generation unit 33 from a later-described center of gravity position displacement amount calculation unit 44 at a cycle of about 10 ms. The correction angle of the upper limb is correction data for returning the center of gravity position by operating the left and right arms when the center of gravity position of the upper body deviates from the target center of gravity position. When the command values Rhs (t) and Lhs (t) are created, the position of the hand is corrected according to the correction angle. For example, when a load is gripped by one arm and the center of gravity of the upper body shifts to the load, the other arm is raised and lowered to move the center of gravity to the target center of gravity. . Command values Rhs (t) and Lhs (t) are created so that such an operation is realized.

  In the gait data storage unit 34, a data group sufficient to determine the posture of the walking robot 100 (gait data: Lfs (t), Rfs (t), Lhs (t), Rhs (t), W ( t)) is stored. The gait data storage unit 34 sends the gait data to the joint angle group calculation device 41 at a cycle of about 10 ms. The walking robot 100 moves the limbs based on the gait data. That is, each joint is driven based on the gait data.

  The joint angle group calculation device 41 calculates a joint angle with respect to the motor of each joint by solving a so-called inverse kinematics calculation based on gait data in which the position of each part is stored. The calculated joint angle is sent to the actuator controller 42. The actuator control device 42 performs drive control of the actuators 1 to 17 of each joint based on the calculated joint angle. Thereby, the joint angle of the walking robot 100 is adjusted, and the walking motion of the walking robot 100 is realized.

  In addition, motor command angles (joint angles) to the respective joints of the left arm portion and the right arm portion are input to the center-of-gravity position displacement amount calculation device 44. That is, when holding a load, the joint angle of the arm holding the load (hereinafter referred to as “the holding arm”) and the arm not holding the load (hereinafter referred to as “non-holding arm”) And the joint angle are respectively input.

  The center-of-gravity displacement calculation device 44 has a function of acquiring a center-of-gravity position, a function of calculating a shift amount of the center-of-gravity position, a function of calculating a joint angle (correction angle) of each joint for correcting the center-of-gravity position, and a target center-of-gravity position And a storage unit (for example, a non-volatile memory). In addition to the target center-of-gravity position, the weight of the load and inertia parameters (weight, center-of-gravity position, moment of inertia, etc.) of each part (arm, neck, foot, etc.) are also stored in the storage unit. The calculation unit (for example, CPU) in the centroid displacement amount calculation device 44 calculates the centroid position, the shift amount of the centroid position, and the correction angle based on information such as the input joint angle and the acquired centroid position. Note that a calculation unit may be provided for each function. In addition, if the center-of-gravity displacement calculation device 44 and the operation instruction generation unit 30 are an integrated device, one CPU in the device may be used.

  The center-of-gravity position displacement amount calculation device 44 performs control as shown in FIG. That is, the center of gravity of the upper body is acquired based on the joint angles of the left and right arms and the known weight of the load, and the amount of deviation of the center of gravity from the target center of gravity is calculated. The target gravity center position is stored in advance in the gravity center position displacement amount calculation device 44. The target center-of-gravity position in this embodiment is the center-of-gravity position when standing upright without gripping a load. Note that the target center-of-gravity position is not limited to the position of the present embodiment, and may be any position that can maintain a good balance. The center of gravity position of the upper body may be calculated based on the joint angle of each joint of the upper body and the weight of the load, and the center of gravity position corresponding to the joint angle of each joint and the weight of the load is stored. A database may be prepared and acquired from the database.

  Next, the correction angle of the center of gravity position is acquired based on the acquired shift amount of the center of gravity position. That is, the joint angle at which the center of gravity of the upper body is on the target center of gravity is acquired. This joint angle may also be acquired by calculation or may be acquired from a database. This correction angle is reflected in the joint angle of the non-gripping arm. That is, the joint angle of the non-gripping arm is adjusted by the correction angle. The correction angle of the non-gripping arm is output to the hand position command value generation unit 33.

  Subsequently, a procedure for moving the arm of the walking robot 100 to balance the upper body, that is, for slightly displacing the center of gravity of the upper body according to the operation of the arm, based on the flowchart of FIG. 4 and the conceptual diagram of FIG. explain. The weight of the load and the position of the center of gravity when the walking robot does not grip the load, that is, the target center of gravity position (FIG. 5A) is stored in advance in the walking robot. In the following description, it is assumed that the walking robot 100 is already holding a load with one arm.

  First, joint angles of both arms are acquired (S1). That is, the joint angle of the gripping arm and the joint angle of the non-gripping arm are acquired. Next, the shift amount of the center of gravity position of the upper body is acquired from these joint angles (S2: FIG. 5B). Specifically, the center-of-gravity position of the upper body is acquired in real time based on the joint angle of each part joint. Then, the difference between the current center of gravity position and the pre-stored target center of gravity position is calculated. This difference is the shift amount of the center of gravity.

  Next, the correction angle of the non-gripping arm is acquired based on the shift amount of the center of gravity position of the upper body (S3). That is, the joint angle of the non-gripping arm is acquired such that the amount of deviation between the center of gravity position of the upper body and the target center of gravity position is a predetermined value (for example, 10 mm) or less. Then, the joint of the non-gripping arm is slightly displaced according to the correction angle (S4: FIG. 5B). By repeating this, the center of gravity position of the upper body can always be maintained near the target center of gravity position, and the walking motion is stabilized even when the load is held by one arm.

  This process is the same even when the walking robot 100 is not holding a load. As a specific operation, for example, if the right arm is swung up forward, the opposite left arm is swung up downward. That is, the center of gravity position when the right arm is operated is acquired, and the difference between the center of gravity position and the target center of gravity position is obtained. Then, the left arm is moved so as to reduce the difference. In other words, while acquiring the position of the center of gravity to be displaced in real time, an operation is performed to secure the center of gravity at a predetermined position by moving the upper limb.

  As described above in detail, the walking robot 100 according to the present embodiment acquires the amount of deviation of the center of gravity of the upper body. Then, based on the deviation amount of the center of gravity position, the correction angle of the upper limb that corrects the deviation of the center of gravity position is acquired. Then, by reflecting this correction angle on the gait data at the hand position, the upper limb is operated to move the center of gravity position to the target center of gravity position. As a result, even if the load is gripped by one arm, the position of the center of gravity can be maintained near the target center of gravity by the operation of the other arm. Therefore, even when the load is gripped by one arm, the walking motion is stable. In addition, the stabilization operation is very simple because it only moves the non-gripping arm. Therefore, a robot has been realized that stabilizes the movement by suppressing movement of the trunk caused by movement of the upper limbs with simple movement.

  For example, when the robot is accompanied by an action of playing a brass instrument with a walking action, it is desirable to perform a stable walking action while holding the brass instrument in one hand. Therefore, as in the embodiment, maintaining a good balance of the upper body stabilizes the position of the brass instrument, improves the appearance, and allows a stable performance.

  Note that this embodiment is merely an example, and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, the number of lower limbs of the walking robot is not necessarily two, and may be three or more. The application range of the present invention is not limited to walking robots. For example, the present invention can be applied to a robot that does not involve walking (such as a robot that moves by wheels or a robot that moves by jumping).

  Further, the present invention is not only applied when a load is gripped on one upper limb. That is, the present invention can be applied to a case where the center of gravity of the upper body is displaced. For example, it can be applied when carrying a load.

It is a skeleton figure which shows the joint structure of the walking robot concerning embodiment. It is a block diagram which shows the function structure of the walking robot concerning embodiment. It is a block diagram which shows control of a gravity center position displacement amount calculation apparatus. It is a flowchart which shows the procedure which carries out the minute displacement of the position of a gravity center. It is a figure which shows the concept which carries out the minute displacement of the position of a gravity center.

Explanation of symbols

1-17 Actuator 25 Posture Control Sensor Group 30 Motion Instruction Generation Device 31 Toe Position Command Value Generation Unit 32 Trunk Position Command Value Generation Unit 33 Hand Position Command Value Generation Unit 34 Gait Data Storage Unit 41 Joint Angle Group Calculation Device 42 Actuator control device 44 Center of gravity position displacement calculation device 100 Walking robot

Claims (6)

In a robot with an upper limb with one end connected to the trunk,
A center-of-gravity position acquisition unit for acquiring a center-of-gravity position of the upper body including the trunk of the robot;
A target position storage unit for storing a target position of the center of gravity of the upper body of the robot;
A center-of-gravity deviation calculation unit that calculates a deviation between the target position stored in the target position storage unit and the center-of-gravity position acquired by the center-of-gravity position acquisition unit;
A robot comprising: a drive unit that drives the upper limb so that a deviation amount calculated by the gravity center deviation amount acquisition unit is a predetermined value or less. The robot according to claim 1, wherein
The upper limb has one or more joints;
The robot, wherein the drive unit moves the joint portion to move the position of the center of gravity. The robot according to claim 1 or 2,
Having two or more upper limbs,
The said drive part drives the at least 1 upper limb among these upper limbs, and moves the said gravity center position, The robot characterized by the above-mentioned. The robot according to any one of claims 1 to 3, wherein
A robot having a structure in which the other end of the upper limb can hold a load. In a control method for a robot having an upper limb with one end connected to the trunk,
A center-of-gravity position acquisition step of acquiring a center-of-gravity position of the upper body including the trunk of the robot;
A center-of-gravity deviation calculation step for calculating a deviation amount between the center-of-gravity position acquired in the center-of-gravity position acquisition step and the target position of the center of gravity of the upper body of the robot;
And a driving step of driving the upper limb so that the amount of deviation calculated in the center-of-gravity deviation amount calculating step is equal to or less than a predetermined value. The robot control method according to claim 5,
In the driving step, when the load is grasped by at least one upper limb, the upper limb not grasping the load is operated.

Images