JP2014087922A - Robot control device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a robot control technology capable of stably controlling a multi-joint robot, which is in a contact state, without use of a contact sensor.SOLUTION: A robot control device and robot control method are disclosed. Geometric information (robot link surface information) on a multi-joint robot being in a contact situation and kinematic information (joint variable) are used to estimate as a contact position a point at which motions intersect, whereby even a link of the multi-joint robot devoid of a contact sensor is provided with a tactile impression. Each of the joints of the robot is controlled based on the contact position for each of the links of the multi-joint robot which is calculated using the geometric information and kinematic information, whereby the multi-joint robot being in the contact state can be stably controlled without use of the contact sensor.

Description

  The present invention relates to a robot control technology, and particularly suitable for detecting a contact position without a contact sensor for a multi-joint robot in a contact state and utilizing this to stably control a multi-joint robot in a contact state. The present invention relates to a robot control apparatus and a robot control method.

  In recent years, with the active development of humanoid robots, the need for research to make such robots fully adapt in the human environment has emerged. The human environment is much more complex and less stylized than the factory assembly line, the space where existing industrial robots were working. Therefore, in order for a robot to adapt well in a human environment, it needs a level of human perception ability. In particular, as the contact situation between the robot and the surrounding environment increases, the need for the robot's tactile abilities is confronted.

  Since the existing method for recognizing the contact position mainly depends only on the tactile sensor, there is a limit to recognition on a portion where the contact sensor is not provided. In particular, most robot tactile sensors are attached to the robot's end-effector, so the algorithm for controlling the robot in contact is also studied only considering the work that is mainly performed by the robot's end-effector. Has been. On the other hand, humans make up for this by using not only the hands but also the tactile sensation of the entire body such as the torso and limbs when performing certain tasks. In particular, when it is difficult to secure a visual field, it is very important to use the sense of touch from the body.

  As an example of using tactile sense, consider the case where a person is sitting on a chair. A person obtains rough information about the position of the chair from the sight and heads toward the chair. However, the position information obtained from the sight is not accurately and quantitatively calculated, and at the moment of sitting on the chair, the posture facing the chair is taken, and thus the field of view for the chair cannot be secured. Therefore, in order for a person to sit on a chair, it is necessary to assist tactile sensation felt through limbs. Thus, it can be said that utilizing the tactile sensation for the entire body is inevitable because it provides a great advantage for the robot to adapt to the human environment.

  Therefore, the present invention has been made in view of the above circumstances, and its purpose is to obtain geometric information (surface information of a robot link (link)) and kinematic information (joint variables) for an articulated robot in contact. It is to propose a robot control technology that can provide a tactile sensation even for a link portion of an articulated robot that is not equipped with a contact sensor by estimating a portion where movements intersect as a contact position.

  Another object of the present invention is to control the joint of the robot according to the contact position with respect to the link of the multi-joint robot calculated using the geometric information and kinematic information, so that the multi-joint robot in a contact state without a contact sensor. It is to propose a robot control technology that can stably control.

  In order to achieve the above object, according to one aspect of the present invention, a portion where the robot motion intersects is detected as a contact position between the robot link and the surrounding environment using the robot geometric information and kinematic information. A contact position detection unit that calculates a joint torque for the link of the robot based on the contact position detected by the contact position detection unit, and controls a movement of the robot based on the calculated joint torque. A robot control device including the same can be provided.

  Here, the contact position detection unit can detect, as the contact position, an intersection corresponding to a change in the movement of surface information according to the link arrangement form of the robot.

  The geometric information may include surface information.

  Further, the surface information may include an n-dimensional model (where n is a natural number including 0).

  The kinematic information may include a joint angle of the robot.

  Further, the joint angle can be detected through an encoder included in the joint device of the robot.

  The contact position detection unit includes a geometric information storage unit that stores geometric information of the robot, a kinematic information storage unit that stores joint variables of the robot, and the robot using the geometric information and joint variables. A contact position calculation unit that calculates a contact position between the link and the surrounding environment may be included.

  Further, the contact position detection unit may further include an error correction unit that corrects an error with respect to the contact position.

  In addition, the error correction unit can correct a contact error that occurs when the surrounding environment is a convex environment.

  Further, the contact position detection unit can calculate the intersection line of the geometric information based on the estimated performance angle of the azimuth change amount of the geometric information.

  The contact state control unit calculates a joint torque for the link of the robot based on a contact position storage unit that stores a contact position calculated by the contact position detection unit and a contact position stored in the contact position storage unit. And a joint torque calculator.

  The contact state control unit may further include a Jacobian calculation unit that calculates contact Jacobian information based on the contact position calculated by the contact position detection unit.

  In addition, the Jacobian calculation unit can update the contact Jacobian information in real time according to the calculated contact position.

  In order to achieve the above object, according to another aspect of the present invention, a portion where the movement of the robot intersects using the geometric information and kinematic information of the robot as a contact position between the link of the robot and the surrounding environment. A robot control method for a robot controller, comprising: a detecting step; a step of calculating a joint torque for the link of the robot based on the detected contact position; and a step of controlling the movement of the robot by the calculated joint torque. Can provide.

  Here, the detecting process may include a process of detecting, as the contact position, an intersection corresponding to a change in movement of surface information according to an arrangement form of the links of the robot.

  The detecting process may include a process of correcting an error with respect to the contact position.

  Further, the detecting step may include a step of calculating intersection lines and intersection points of the geometric information according to an estimated performance angle of the azimuth change amount of the geometric information.

  The calculating may further include calculating contact Jacobian information based on the contact position.

  Further, the contact Jacobian information may be updated in real time according to the contact position.

  According to the present invention, it is possible to determine an articulated robot in a contact state without a contact sensor by determining a portion where movements intersect as a contact position using geometric information and kinematic information for the articulated robot in a contact state. There is an effect that it can be stably controlled.

It is a block diagram with respect to the robot control apparatus by embodiment of this invention. It is a conceptual diagram explaining the case where a contact position is detected geometrically with the contact position detection apparatus of FIG. It is a conceptual diagram which shows more specifically the contact position detection technique of FIG. FIG. 5 is a conceptual diagram illustrating an example of an error correction technique using a linear model in detecting a contact position according to an embodiment of the present invention. 4 is a flowchart illustrating an example of a robot control method according to an embodiment of the present invention, specifically, a contact position detection process of an articulated robot. It is a conceptual diagram explaining the case where a plane model is used in detecting a contact position by embodiment of this invention. It is a conceptual diagram explaining the calculation method of the Jacobian calculation part of FIG. 1 exemplarily. 5 is a flowchart illustrating a robot control method according to an embodiment of the present invention, and a process of controlling the robot according to a specifically estimated contact position. 5 is a flowchart illustrating a robot control method according to an embodiment of the present invention, and a process of controlling the robot according to a specifically estimated contact position.

  Advantages and features of the present invention and methods of achieving them will be apparent with reference to the embodiments described in detail below in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and can be realized in various forms different from each other, provided that the present embodiments complete the disclosure of the present invention. The present invention is provided to enable a person having ordinary knowledge in the technical field of the present invention to fully understand the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

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

  FIG. 1 is a block diagram of a robot control apparatus according to an embodiment of the present invention, and can largely include a contact position detection unit 100 and a contact state control unit 200.

  In the embodiment of the present invention, the contact position detection unit 100 and the contact state control unit 200 are collectively referred to as a robot control device, and the contact position detection unit 100 and the contact state control unit 200 operate separately. It is necessary to make it known that there is a complementary relationship.

  As shown in FIG. 1, the contact position detection unit 100 may include a geometric information storage unit 102, a kinematic information storage unit 104, a contact position calculation unit 106, an error correction unit 108, and the like.

  Here, the geometric information storage unit 102 can perform a function of storing geometric information of an articulated robot, for example, geometric information of a robot link where contact occurs. Here, the geometric information may include surface information of the robot link, and the surface information may be a zero-dimensional model (point), a one-dimensional (straight) model, a two-dimensional (planar) model, or a three-dimensional (solid) model. Any one of the models can be included.

  The kinematics information storage unit 104 can perform a function of storing robot kinematic information, for example, each joint angle that is a joint variable of the robot. The joint variable of the robot can be received from an encoder (not shown) provided in the joint apparatus of the robot. Since such an encoder can be easily understood by those having ordinary knowledge in the technical field of the present invention, a specific configuration and description of the technology are omitted.

  The contact position calculation unit 106 can perform a function of calculating the contact position information of the robot link using information stored in the geometric information storage unit 102 and the kinematic information storage unit 104, for example, geometric information and kinematic information.

  At this time, the contact position calculation unit 106 may include an equivalent angle-axis technique so that the contact position information can be calculated in response to a sudden contact movement. In addition, the contact position calculation unit 104 calculates a temporary contact position so that the contact position information can be calculated even when the intersection between the geometric information stored in the geometric information storage unit 102 cannot be calculated. Techniques can be included.

  The error correction unit 108 can perform a function of correcting the contact position information calculated through the contact position calculation unit 106. Specifically, the error correction unit 108 can correct a contact position estimation error that may occur by using a geometric model.

  Meanwhile, the contact state control unit 200 can include a contact position storage unit 202, a Jacobian calculation unit 204, a joint torque calculation unit 206, and the like.

  Here, the contact position storage unit 202 can perform a function of storing the contact position information calculated by the contact position calculation unit 106 of the contact position detection unit 100.

  The Jacobian calculator 204 can perform a function of calculating contact Jacobian information based on the contact position information calculated by the contact position calculator 106. Here, the contact Jacobian information can include, for example, the joint angle of the robot link, the correspondence relationship between the motion coordinate system servos, etc., and these information are determined in real time by the contact position information calculated by the contact position calculation unit 106. Can be updated.

  The joint torque calculation unit 206 calculates a torque value by using the contact position information stored in the contact position storage unit 202 and the contact Jacobian information calculated by the Jacobian calculation unit 204 in order to control the contact state. A function of applying a torque value to a joint motor (not shown) in the robot joint apparatus can be performed. The joint motor can be driven by applying such a torque value to the joint motor, and the joint variable of the encoder is again provided to the kinematic information storage unit 104 of the contact position detection unit 100 by driving the joint motor. Can form a common relationship.

［式１］から分かるように、関節トルク値ベクトルГは、接触力を制御するトルクとその零空間で動きを制御するトルクからなり得る。 For control of the robot in contact, the joint torque value vector Γ can be expressed as:

As can be seen from [Expression 1], the joint torque value vector Γ can be composed of a torque for controlling the contact force and a torque for controlling the movement in the null space.

  Hereinafter, a specific embodiment related to the robot control method according to the embodiment of the present invention, specifically the contact position detection method of the articulated robot, and the contact state control method based thereon will be described in more detail together with the above-described configuration.

  FIG. 2 is a conceptual diagram illustrating a case where the contact position is detected geometrically by the contact position detection unit 100 of FIG. 1, and the robot link 1 of the robot that can move by a joint is moved by the contact environment 2. A case where the contact position is detected when there is a limit will be described.

  First, the configuration information of the robot link 1 is known from the joint angle information due to the characteristics of the robot, and it is well known that the geometric information of the robot link according to this array configuration can be stored in the geometric information storage unit 100. is there.

  In the contact state between the contact environment 2 and the robot link 1 shown in FIG. 2, the movement of the robot can be restricted by the contact position. At this time, the movement of the geometric shape due to the movement of the robot can also be tracked through the geometric information storage unit 102, and the geometric shape of the robot has an intersection C in the movement. In the embodiment of the present invention, such an intersection C can be estimated as a restriction on movement, that is, a contact position.

  FIG. 3 is a conceptual diagram more specifically showing the contact position detection method shown in FIG. In order to facilitate understanding, assuming that the link shape of the robot can be expressed by a one-dimensional model, for example, a straight line model, the straight line model of the robot link where contact has occurred can be stored in the geometric information storage unit 102.

  Since the arrangement form of the robot link can be grasped through an encoder mounted in the joint device, a change in the linear model due to the movement of the robot can also be tracked. At this time, when the orientation of the linear model changes by a certain amount or more, it is possible to search for the restriction position generated in the movement of the robot by calculating the intersection between the linear models at the moment before / after the change. At this time, the amount of change in orientation used is referred to as an “estimated performance angle”, and such an estimated performance angle can be used to determine whether or not to execute the contact position detection (estimation) method.

  At this time, the contact position detection method can include a method in which the contact position can be estimated even when the intersection cannot be calculated at the position where the relationship between the two straight lines is entangled. For example, when an intersection cannot be calculated in a positional relationship involving straight lines, a temporary contact position can be determined by calculating a point where the distance between the two straight lines is the closest by the contact position detection method.

  FIG. 4 is a conceptual diagram exemplarily explaining the error correction technique of the error correction unit 108 of FIG. 1 in detecting a contact position through a linear model according to an embodiment of the present invention.

  Since the contact position estimation algorithm tracks the movement of the geometric model and calculates the intersection point, an error may occur when contact with a convex environment (circular shape) occurs as shown in FIG.

At this time, error correction can be performed through correction of an error value between the actual contact position and the estimated contact position, as in [Equation 2] below.

The “unintended motion analysis” algorithm included in the contact position calculation unit 106 described above can track the motion of the geometric model by analyzing the motion of the robot link through the equivalent angle axis technique as follows.

  FIG. 5 is a flowchart illustrating a robot control method according to an embodiment of the present invention, specifically a contact position detection method for an articulated robot, and illustrates an expanded concept of the contact position estimation method. is there.

  If the surface of the contacting link is a two-dimensional model, that is, a planar geometric model, the contact position can be calculated by applying the planar model as shown in FIG. Since the movement of the plane model is also limited by the contact position, the trace of the plane changes while leaving a straight line including the contact position as an intersection line. All intersecting lines generated from the movement limitation due to the contact are always straight lines including the contact point C (indicated by X in FIG. 6).

  As shown in FIG. 5, when the robot first recognizes the first contact with respect to the contact environment (S100), the contact position calculation unit 106 applies the first plane model from the geometric information storage unit 102, and then It can be determined whether the azimuth change amount of the first plane model by the control of exceeds the estimated performance angle (S102) (S104). At this time, since an accurate contact position is not known, unstable control must be performed.

  When the azimuth change amount of the first plane model exceeds the estimated performance angle, the contact position calculation unit 106 can calculate the intersection information of the first straight line and, at the same time, the second plane from the geometric information storage unit 102. A model can be applied (S106). Similarly, at this time, the control is unstable in a state where the contact position is unknown.

  Similarly, the contact position calculation unit 106 can determine whether the azimuth change amount of the second planar model exceeds the estimated performance angle (S108), calculates the intersection of the second straight line in the same manner, and calculates the third The planar model can be applied (S110).

  Since the two intersecting lines calculated in this way have one common point called the contact position, the intersection of the two straight lines can be calculated as the contact position after all (S112) (S114).

  If the contact position is calculated in this way, the contact position calculation unit 106 can provide the corresponding contact position information to the contact state control unit 200, and the contact state control unit 200 stores the corresponding contact position information in the contact position storage unit 202. The contact Jacobian according to the contact position can be calculated through the Jacobian calculation unit 204 while temporarily storing.

  Further, the contact state control unit 200 can calculate the joint torque using the contact position and the contact Jacobian through the joint torque calculation unit 206, and the calculated joint torque can be applied to a joint motor (not shown). Thereby, the stable control of the robot can be executed (S116).

  At this time, in the embodiment of the present invention, it is possible to continuously monitor the azimuth change amount of the plane model added in performing such robot control, and the azimuth change amount of any plane model exceeds the estimated performance angle. In addition, the intersection of straight lines with respect to an arbitrary plane model can be calculated and fed back to the step (S112) (S118) (S120).

  FIG. 7 is a conceptual diagram illustrating a method for calculating contact Jacobian information by the Jacobian calculation unit 110 of FIG.

The contact Jacobian information is updated in real time using the following [Formula 6] according to the contact position calculated by the contact position estimation method. At this time, the control center and the contact position may be the same or different from each other.

  8 and 9 are block diagrams in which the overall configuration of the robot control method according to the embodiment of the present invention, specifically, the contact position detection method, is arranged. The contact position estimation method and the contact state control interacting therewith are shown. 2 is an overall control framework block diagram of the method.

  First, the contact position estimation method can be started as shown in FIG.

  If the robot is controlled without knowing the initial contact position, an unintended movement may occur.

  The contact position estimation method that analyzes this movement can store the contact position in the contact position storage unit 202 of the contact state control unit 200 as shown in FIG. 9 by estimating the contact position (S200).

  Thereafter, the contact force control space and the motion control space as described above can be defined (S202).

  The Jacobian calculation unit 204 can reconstruct the contact Jacobian based on the contact position estimated by the contact position calculation unit 106 (S204).

  The contact force is controlled in the contact space according to the given contact position, and the movement of the robot can be controlled in the motion control space (S206). The contact force control performs control for maintaining contact between the robot and the environment, and the robot motion control creates a motion that can estimate the contact position.

  Such a contact position estimation method and a contact state control method can act complementarily.

Claims (9)

A contact position detection unit that detects a portion where the movement of the robot intersects using the geometric information and kinematic information of the robot as a contact position between the link of the robot and the surrounding environment;
A robot control apparatus comprising: a contact state control unit that calculates joint torque with respect to the link of the robot based on the contact position detected by the contact position detection unit, and controls movement of the robot using the calculated joint torque.   The robot control apparatus according to claim 1, wherein the contact position detection unit detects an intersection corresponding to a change in movement of surface information according to an arrangement form of links of the robot as the contact position.   The robot control apparatus according to claim 1, wherein the geometric information includes surface information of an n-dimensional model (where n is a natural number including 0).   The robot control apparatus according to claim 1, wherein the kinematic information includes a joint angle detected through an encoder included in the joint apparatus of the robot. The contact position detector is
A geometric information storage unit for storing geometric information of the robot;
A kinematics information storage unit for storing joint variables of the robot;
A contact position calculation unit that calculates a contact position between the link of the robot and the surrounding environment using the geometric information and joint variables;
The robot control device according to claim 1, further comprising: an error correction unit that corrects an error with respect to the contact position and corrects a contact error that occurs when the surrounding environment is a convex environment.   The robot control apparatus according to claim 1, wherein the contact position detection unit calculates an intersection line of the geometric information based on an estimated performance angle of an azimuth change amount of the geometric information. The contact state controller is
A contact position storage unit that stores a contact position calculated by the contact position detection unit;
A joint torque calculator for calculating a joint torque for the link of the robot according to a contact position stored in the contact position storage;
2. A Jacobian calculation unit that calculates contact Jacobian information based on a contact position calculated by the contact position detection unit, and updates the contact Jacobian information in real time according to the calculated contact position. The robot control device described in 1. Detecting a portion where the movement of the robot intersects using the geometric information and kinematic information of the robot as a contact position between the link of the robot and the surrounding environment;
Calculating a joint torque for the link of the robot according to the detected contact position, and calculating contact Jacobian information updated in real time according to the contact position;
A robot control method for a robot control apparatus, comprising: controlling movement of the robot by the calculated joint torque. The detecting process includes:
A process of detecting an intersection corresponding to a movement change of surface information according to an array form of the robot links as the contact position;
Correcting the error relative to the contact position;
The robot control method of the robot controller according to claim 8, further comprising: calculating an intersection line and an intersection point of the geometric information according to an estimated performance angle of an azimuth change amount of the geometric information.

Images