JP7439206B2 - Information processing methods, information processing devices, programs, recording media, production systems, robot systems, article manufacturing methods - Google Patents

Description

The present invention relates to an information processing method and an information processing apparatus for generating a trajectory of a robot arm.

BACKGROUND ART Conventionally, configurations have been known in which industrial robot devices are arranged in production systems (production lines) for industrial products such as automobiles and electrical appliances to automate tasks such as welding and assembly. In this type of production system, robot devices, workpieces, workpiece stands, jigs, and other peripheral equipment are arranged in such a way that they may interfere with each other (contact, collide). In recent years, simulations using a virtual environment are sometimes used in designing the movement trajectory of the arm of a robot device in such a production system.

When simulating the operation of a robot device offline using a simulator device, 3D (three-dimensional) models such as a robot arm, workpiece stand, jig, and other peripheral devices are placed in a virtual environment. For example, such a simulator device generates a trajectory between teaching points of a robot arm created in advance, and performs a simulation to operate a 3D model of the robot arm in a virtual environment on that trajectory to verify it. be. The movement of the robot arm model can be displayed in the form of a video on the virtual display screen of the display of the simulator device.

Naturally, the simulation results will vary greatly depending on the motion trajectory of the robot arm. If the trajectory of the robot arm is inappropriate, a part of the robot arm's motion trajectory may enter the area where the robot arm cannot operate, the robot arm may interfere with other objects, or the cycle time may be reduced due to unnecessary motion. may be delayed.

In the conventional method, the operator used trial and error on the screen to create teaching points for the robot arm that satisfied the conditions that the robot arm would not enter an area where it could not operate or that the robot arm would not interfere with peripheral equipment. . In this case, since the conditions of movability and non-interference are first taken into consideration, a robot trajectory that allows the robot to operate at an optimal operating speed is not necessarily generated, which may slow down the cycle time. In that case, it was necessary to reconsider the teaching points of the robot arm and perform manual work to reinstall it.

On the other hand, when a robot device is used in a production system (line), it takes a large amount of man-hours for a process designer to create teaching points, so there is also the problem of rising labor costs. Therefore, in recent years, methods and devices have been proposed that use a computer to improve the efficiency of the teaching work of a robot arm, instead of direct teaching by a teacher.

Non-Patent Document 1 listed below discloses a trajectory generation method that avoids interference with obstacles around a robot arm and minimizes the torque of a motor used for the joints of the robot arm. FIG. 8 schematically shows a method of generating a robot arm trajectory in Non-Patent Document 1. In FIG. 8, robot arm A is a simplified robot arm with two degrees of freedom having two rotation axes J1 and J2, and Ob indicates an obstacle.

In FIG. 8, p1, p2, . Among these positions, p1 indicates the start position (start teaching point) of the movement, and p9 indicates the target position (target teaching point) of the movement. Further, p2 to p8 indicate intermediate command values placed between the starting position (p1) and the target position (p9). For example, it is possible to instruct the robot arm A to take the postures p1, p2, . In this case, the operating time of the robot arm between the starting position (p1) and the target position (p9) is calculated as control period x (9-1). In the case of Non-Patent Document 1, the number of intermediate command values (p2 to p8) is determined in advance as a constant, and in this case is seven. In FIG. 8, the robot arm and the obstacle Ob interfere at p4 and p5, but a trajectory that can avoid interference can be generated by the following method.

First, joint angles corresponding to intermediate command values p2, p3, . . . p8 are smoothly displaced to generate N new intermediate command values ri2, ri3, . Next, by repeating the process of evaluating the intermediate command values ri2, ri3, ...ri8 (i = 1, ...N) and displacing the intermediate command values p2, p3, ...p8 based on the evaluation values, Optimize your trajectory. In Non-Patent Document 1, the amount of penetration between the robot arm A and the obstacle Ob and the motor torque used for each joint axis are used as evaluation values of the intermediate command value. By using such evaluation values, a trajectory is generated in which the robot arm A does not interfere with the obstacle Ob and the motor torque used for each joint axis does not become overloaded.

Kalakrishnan, Mrinal, et al. "STOMP: Stochastic trajectory optimization for motion planning." Robotics and Automation (ICRA), 2011 IEEE International Conference on IEEE, 2011.

As described above, the technique of Non-Patent Document 1 generates a trajectory in which the robot arm A and the obstacle Ob do not interfere with each other and the motor torque used for each joint axis does not become overloaded. However, in the technique of Non-Patent Document 1, the number of intermediate command values is a fixed number, and therefore the operation time from the start teaching point (p1) to the target teaching point (p9) is fixed, such as arm movement. There is a problem with not being able to optimize your time. Furthermore, if the operating time is fixed, it becomes difficult to satisfy constraints on the motor torque used for each joint axis and other constraints. Such constraint conditions related to robot motion that are difficult to achieve include, for example, constraint conditions related to joint axis torque, joint angular velocity, joint angular acceleration, jerk, hand speed, and hand acceleration. That is, the conventional technology described in Non-Patent Document 1 has the following problems. That is, in a region where the number of intermediate command values is too small, there is no guarantee that the constraint conditions regarding robot operation are satisfied, and conversely, in a region where the number of intermediate command values is too large, a trajectory with an optimal operating time cannot be obtained.

In view of the above problems, an object of the present invention is to reliably generate an optimal trajectory that satisfies the constraints regarding robot motion.

One aspect of the present invention provides an information processing method for acquiring a trajectory for operating a robot arm between a first position and a second position, in which a group of intermediate teaching points defines a path from the first position to the second position. an intermediate trajectory acquisition step of setting at least two intermediate trajectories and acquiring at least two intermediate trajectories based on the intermediate teaching point group; an evaluation step of acquiring an evaluation value on the intermediate trajectory acquired in the intermediate trajectory acquisition step; The information processing method is characterized by comprising a trajectory obtaining step of obtaining a trajectory for operating the robot arm based on a predetermined intermediate trajectory among the intermediate trajectories based on the evaluation value.
Another aspect of the present invention is an information processing apparatus that acquires a trajectory for operating a robot arm between a first position and a second position, in which intermediate teaching is provided that defines a path from the first position to the second position. At least two point groups are set, at least two intermediate trajectories are acquired based on the intermediate teaching point group , an evaluation value is acquired on the acquired intermediate trajectory, and a predetermined one of the intermediate trajectories is determined based on the evaluation value. The information processing apparatus is characterized in that a trajectory for operating the robot arm is acquired based on an intermediate trajectory of the robot arm.

With the above configuration, according to the present invention, it is possible to reliably generate an optimal trajectory that satisfies the constraint conditions regarding robot operation.

FIG. 1 is an explanatory diagram showing a functional configuration of a trajectory generation device according to an embodiment of the present invention. FIG. 2 is an explanatory diagram showing a two-axis configuration in a robot arm according to an embodiment of the present invention. FIG. 2 is an explanatory diagram showing a teaching point group and a trajectory according to an embodiment of the present invention. FIG. 3 is a flowchart diagram illustrating trajectory optimization processing according to an embodiment of the present invention. (a) to (e) are explanatory diagrams showing trajectory optimization processing according to an embodiment of the present invention. FIG. 2 is an explanatory diagram showing a teaching point group and a trajectory according to an embodiment of the present invention. (a) to (e) are explanatory diagrams showing trajectory optimization processing according to an embodiment of the present invention. FIG. 2 is an explanatory diagram showing a method of orbit control according to the prior art. FIG. 1 is a block diagram showing a schematic configuration of a control device applicable to an embodiment of the present invention. FIG. 1 is an explanatory diagram showing a robot device that can be placed in a production system according to an embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings. Note that the configuration shown below is just an example, and for example, the detailed configuration can be changed as appropriate by those skilled in the art without departing from the spirit of the present invention. Moreover, the numerical values taken up in this embodiment are reference numerical values, and do not limit the present invention.

<Embodiment 1>
FIG. 1 shows the configuration of a trajectory generation device according to this embodiment. In this embodiment, the device that generates a trajectory according to the present invention is referred to as a “trajectory generation device,” but this trajectory generation device may be provided as a product such as a robot simulator device.

The trajectory generation device shown in FIG. 1 includes an arithmetic processing section 1, an operation section 2 for instructors to input data, a recording section 3 for recording operation programs, etc., and a section for displaying the operation trajectory of the robot arm. A display section 4 is provided. This trajectory generation device can be configured by computer hardware such as a PC (personal computer), for example. Here, a specific example of the configuration of the arithmetic processing section 1 is shown in FIG.

FIG. 9 shows a configuration example of a control device 1000 corresponding to the trajectory generation device, particularly the main part of the arithmetic processing section 1 (FIG. 1). As shown in the figure, this control device 1000 is a control system consisting of blocks arranged around a CPU 1601. Note that the configuration consisting of blocks arranged around the CPU 1601 can be applied in almost the same way, for example, to a robot control device (200: FIG. 10), which will be described later.

The control device 1000 in FIG. 9 includes a CPU 1601 as a main control means, a ROM 1602 as a storage device, and a RAM 1603. The ROM 1602 can store a control program for the CPU 1601, constant information, etc. for implementing control procedures to be described later. Further, the RAM 1603 is used as a work area for the CPU 1601 when executing a control procedure to be described later.

When the configuration in FIG. 9 is the arithmetic processing unit 1 (FIG. 1), the user interface device includes, for example, a display 1608 (display unit 4 in FIG. 1) and an operation unit 1609 (operation unit 2 in FIG. 1). 1607. The operation unit 1609 can be composed of, for example, a full keyboard and a pointing device, and constitutes a user interface for an operator who performs trajectory simulation and verification.

The control device 1000 in FIG. 9 includes a network interface 1605 as a communication means for communicating via the network NW. The arithmetic processing unit 1 (FIG. 1) controls teaching point data, trajectory data, etc. to the actual robot arm A (or its robot control device 200 (FIG. 10)) via the network interface 1605 to the network NW. Can send and receive information. In that case, the network interface 1605 is configured using a communication standard such as wired communication such as IEEE 802.3 or wireless communication such as IEEE 802.11 or 802.15. However, it is of course possible to adopt any other communication standard for the network NW.

Note that a control program for the CPU 1601 for realizing the control procedure described below can also be stored in an external storage device 1604 such as an HDD or SSD, or a storage unit such as the ROM 1602 (for example, an EEPROM area). In that case, the control program of the CPU 1601 for implementing the control procedure described below can be supplied to each of the above-mentioned storage units via the network interface 1605, and can be updated to a new (different) program. Alternatively, the control program of the CPU 1601 for realizing the control procedure described below is supplied to each of the above-mentioned storage units via storage means such as various magnetic disks, optical disks, and flash memories, and a drive device for that purpose, Also, its contents can be updated. The various storage means and storage units storing the control program for the CPU 1601 for implementing the above-described control procedure constitute a computer-readable recording medium that stores the control procedure of the present invention.

In the case of the robot control device 200 (FIG. 10), driver circuits for driving motors, solenoids, etc. (not shown) of various parts of the robot arm A are connected to the interface 1606 in the configuration shown in FIG. Further, in the case of the robot control device 200, the user interface consisting of the display 1608 and the operation unit 1609 may be replaced with an operation terminal such as a teaching pendant (for example, 204 in FIG. 10).

Generally, a robot arm is composed of joints and links, and there are various types of joint mechanisms such as rotary joints, translational joints, and ball and socket joints. In this embodiment, the robot arm that generates the trajectory has a configuration in which links are connected by rotary joints, as shown in FIG.

FIG. 2 is an example of a robot arm that is the object of trajectory generation in this embodiment. The robot arm A in FIG. 2 is shown in a simplified configuration for ease of explanation.

The robot arm A in FIG. 2 is equipped with two axes J1 and J2 consisting of two rotational joints. Below, the joint angles (joint positions) of the axes J1 and J2 of these joints are expressed as θ1 and θ2, respectively. Further, a TCP (Tool Center Point) is defined as a reference position at the tip of the axis J2. In this embodiment, the teaching point that defines the position of the robot arm A is expressed as the position of this TCP. Further, the trajectory of the robot arm A to be generated is generated as a trajectory along which this TCP moves.

Generally, when joint angles θ1 and θ2 of axes J1 and J2 are given, the position of TCP can be obtained by kinematic calculation, and when the position of TCP is given, TCP can be obtained by inverse kinematic calculation. The joint angles θ1 and θ2 of the axes J1 and J2 when the robot takes that position can be obtained. In the following, when referring to TCP, it may be simply referred to as a "stooge."

Note that although the robot arm A is illustrated as having a very simplified configuration for ease of understanding, this configuration is not limited to the embodiment of the present invention. For example, when a person skilled in the art implements the present invention, a six-axis articulated robot arm or a direct-acting robot arm configuration can be used as the robot arm A. The configuration and control procedure of the control system related to the robot arm of this embodiment described below can be easily extended when using those robot arms.

Next, the moving operation of robot arm A will be explained. When moving the robot arm A, the teaching point indicating the start position of the movement is called the start teaching point, and the teaching point indicating the target position is called the target teaching point. The teaching point of the robot arm A can be determined by the position and posture of the hand (TCP) or the joint axis angle. In addition, by inverse kinematics calculation, the position and posture of the hand (TCP) can be converted into the joint angle of each joint axis, and conversely, by (forward) kinematics calculation, the joint angle of each joint axis can be converted to the joint angle of each joint axis. It is possible to convert the position and posture of

Here, the start teaching point and the target teaching point are assumed to be Ps and Pg, respectively. Furthermore, the teaching points arranged between the start teaching point and the target teaching point are called intermediate teaching points, and are expressed as P1, P2, . . . , Pn. Moreover, when P1, P2, . . . , Pn are collectively referred to, they may be called an intermediate teaching point group.

Interpolation methods such as Spline interpolation, B-Spline interpolation, and Bezier curve interpolation are known as methods for smoothly interpolating the group of intermediate teaching points P1, P2, . . . Pn using curves. By using these interpolation methods to generate a path that smoothly connects teaching points, the robot arm A can be smoothly operated.

In this specification, a "motion path" or "path" of a robot arm refers to a trajectory of the motion of the robot arm that does not include temporal concepts such as speed. In addition, the "motion trajectory" or "trajectory" of the robot arm means an information body that has information on the motion speed of the robot arm in addition to the above-mentioned "(motion) path" of the robot arm, and in this specification, It is clearly distinguished from the above-mentioned "(operation) route". Note that in robot control technology, a "trajectory" may be expressed by a command value data string of joints (angles) of a robot arm for each unit time, for example, every cycle of a control clock of a robot controller.

Minimum time control is a method for generating a trajectory including speed information for the robot arm path generated using the above interpolation method. By using the shortest time control, it is possible to obtain a trajectory with the shortest operating time based on the path generated by interpolation while adhering to the physical constraints of the robot arm. Note that the shortest time control is a technique for determining the moving speed that takes the shortest time on a fixed route, and the route on which the robot arm is operated depends solely on the group of intermediate teaching points P1, P2, . . . Pn. Other physical constraints on the robot arm may include, for example, a joint torque constraint, a joint angular velocity constraint, a joint angular acceleration constraint, a jerk constraint, a hand speed constraint, and a hand acceleration constraint. In the following, a trajectory generated using the shortest time control will be expressed as a sequence of position command values of the robot arm for each control period as p1, p2, . . . pt.

Figure 3 shows how robot arm A (3D model simulating: robot arm model) and obstacle Ob (3D model simulating: obstacle model) are both placed in the operating environment (virtual environment). ing. Further, FIG. 3 shows a start teaching point Ps, a target teaching point Pg, intermediate teaching point groups P1, P2, . . . Pn, and trajectories (p1, p2, . . . pt) generated thereby.

In the trajectory (p1, p2,...pt) shown in FIG. 3, the robot arm A interferes with the obstacle Ob at p4 and p5, and in this trajectory, the robot arm A cannot move from the start teaching point Ps to the target teaching point Pg. Can not. The purpose of this embodiment is to create an optimal group of intermediate teaching points P1, P2, between the starting teaching point Ps and the target teaching point Pg, where the robot arm and obstacles do not interfere (and other constraint conditions are also satisfied). ...The purpose is to find Pn. Note that the trajectory optimization calculation is possible even when the obstacle Ob is not limited to being stationary, but is moving.

FIG. 4 is a flowchart describing the main control procedures of the trajectory generation method according to this embodiment. The control procedure shown in FIG. 4 can be stored in the ROM 1602 (or external storage device 1604, etc.) as a control program for the CPU 1601. Further, FIG. 5 shows the control procedure of each step in FIG. 4 in the same manner as in FIG. 3. In the following, trajectory generation and optimization will be performed with respect to the 3D model of the robot arm A and the obstacle Ob. However, in order to simplify the description, the term "3D model" will be omitted and the control target will be the robot arm. It may be written as if it were A or an obstacle Ob.

In step S100 of FIG. 4, a model of robot arm A, constraints, start teaching point Ps, and target teaching point Pg in the work space where robot arm A performs work are input (FIG. 5(a)). These inputs can be made by the user via a user interface configured by, for example, the operating section 2 and the display section 4. In addition, in particular, the start teaching point Ps and the target teaching point Pg are inputted by the user via the virtual display (GUI) on the display unit 4, or are determined by the CPU 1601 when trajectory generation is performed by AI processing. It's okay.

The model of the robot arm A described above is design information of the parts constituting the robot arm, and includes information such as the moment of inertia of each link, mass, position, orientation, and number of axes. Furthermore, the constraint conditions define physical constraints of the robot arm, and include joint torque constraints, joint angular velocity constraints, joint angular acceleration constraints, jerk constraints, hand speed constraints, hand acceleration constraints, and the like.

In step S101, intermediate teaching points (first intermediate teaching point group) P1, P2, ...Pn as initial values are set between the starting teaching point Ps and the target teaching point Pg of the robot arm A given in step S100. (Fig. 5(b)). In this embodiment, as shown in FIG. 5(b), the number of intermediate teaching points to be generated is n, and the intermediate teaching points are sequentially P1, P2, . . . Pn.

A conceivable method for generating intermediate teaching points is to use a route planning algorithm that calculates a route that avoids obstacles. There are many route generation methods, such as the potential method, PRM (Probabilistic Road Map), and RRT (Rapidly-exploring Random Tree). Furthermore, the route generation method is not limited to the above route generation means, and other route generation methods such as the visible graph method, the cell division method, and the Voronoi diagram method may also be applied. Alternatively, a process of linearly interpolating between the start teaching point and the target teaching point may be used instead of using the path planning algorithm. Note that the path planning technique described above calculates a path that guarantees avoidance of interference only when teaching points are connected by straight lines. Therefore, avoidance of interference may not always be guaranteed on a path obtained by interpolating the intermediate teaching point group P1, P2, . . . Pn with a curve.

For example, as shown in FIG. 5(b), the intermediate teaching point group P1, P2,...Pn (first intermediate teaching point group) corresponds to a trajectory that interferes with the obstacle Ob, for example. In this embodiment, even if the process starts from the intermediate teaching point group P1, P2,...Pn (first intermediate teaching point group) as such initial values, the intermediate teaching points are set so as to generate an optimal trajectory. The groups P1, P2, . . . Pn (first intermediate teaching point group) can be moved.

Alternatively, the intermediate teaching point group P1, P2,...Pn (first intermediate teaching point group) as initial values can be set by the user through the user interface of the operation unit 2 and the display unit 4 in the virtual environment on the screen. You can also set it by plotting it.

In step S102 of FIG. 4, spatial displacement is applied to the intermediate teaching point group P1, P2, ...Pn (first intermediate teaching point group), and a new intermediate teaching point group R1, R2, ...Rn (first intermediate teaching point group) is given. (FIG. 5(c): intermediate teaching point generation step). As a method for giving this displacement, for example, a method of adding (adding) a random value as a parameter for giving spatial displacement to each intermediate teaching point can be considered. However, if a method of simply applying random random values is adopted, the teaching points may be arranged in an oscillatory manner, and the motion of the robot arm may not be smooth. Generally, when the motion of the robot arm becomes vibratory, the motion time tends to increase, so it is undesirable for the teaching points to be arranged in a vibratory manner.

Therefore, in order to give a spatial displacement, a correlation is given between the random numbers applied to adjacent intermediate teaching points, thereby making it possible to smooth the trajectory (route). For example, let the joint values of one axis of the robot arm in the intermediate teaching point group P1, P2, ...Pn be θ11, θ12, ...θ1n, and consider a multivariate normal distribution using these as variables. In this way, by giving a positive value to the covariance in the variance-covariance matrix, the joint values of adjacent intermediate teaching points can be correlated, and smooth random numbers can be generated along the path. It becomes possible.

In step S103, a curve is interpolated between the intermediate teaching point groups R1, R2, . . . Rn, and a trajectory is generated using shortest time control (trajectory generation step). Here, if the purpose is to avoid a stationary obstacle, it is sufficient to evaluate the interference of robot arm A on a "route" interpolated with a curved line, but when considering a moving obstacle, the time Since the axis must also be taken into consideration, the "trajectory" is considered in this embodiment.

In step S104, it is determined whether the generated trajectory satisfies the constraints. If the trajectory does not satisfy the constraints, the process returns to S102, and if the trajectory satisfies the constraints, the process proceeds to S105. The constraint condition determined in step S104 is a constraint that cannot be constrained by the shortest time control technique used in step S103. The constraint condition determined in step S104 is that the mechanism of robot arm A does not protrude outside the movable range, at least on the trajectory generated in step S103. In addition, other conditions may be considered as the constraint conditions determined in step S104, such as joint torque constraints, joint angular velocity constraints, joint angular acceleration constraints, jerk constraints, hand speed constraints, or hand acceleration constraints of the robot arm. In step S104, a determination can be made to generate a trajectory that satisfies any one or more of these constraints.

In step S105, the intermediate teaching point group R1, R2, . . . Rn and the trajectory generated based on them are saved. The intermediate taught point groups to be saved are expressed as Ri1, Ri2, . . . Rin to distinguish them from other saved intermediate taught point groups. i is the order in which they were saved.

In step S106, it is determined whether the number of saved intermediate taught points and trajectories has reached a certain constant N. In step S106, if the number of saved intermediate taught points and trajectories has not reached N, the process returns to step S102, and if the number has reached N, the process proceeds to step S107.

In step S107, an evaluation value is given to the saved N intermediate teaching point group Ri1, Ri2, . . . Rin (i = 1 to N) (FIG. 5(d): evaluation step). In this embodiment, this evaluation value is used to displace (move) the intermediate teaching point group P1, P2,...Pn (first intermediate teaching point group) so as to generate an optimal trajectory.

Further, this evaluation value is generated, for example, by evaluating the trajectory corresponding to the intermediate teaching point group Ri1, Ri2, . . . Rin (i = 1 to N). For example, in this embodiment, in order to obtain a trajectory that avoids interference with the obstacle Ob, the amount of interference between the robot arm and the obstacle is used as an evaluation value. For example, the amount of interference may be the interference time when the robot arm and the obstacle occupy the same space, the amount of penetration, or the interference distance (or the overlapping volume of the sweep spaces of the two). In this embodiment, for example, the interference time is used as the amount of interference and is used as the evaluation value.

In the example of FIG. 5(d), evaluation values generated based on the amount of interference (interference time or amount of penetration) are shown for three intermediate teaching point groups. This evaluation value is 10 for the second intermediate teaching point group R11, R12...R1n, 30 for R21, R22...R2n, and 50 for R31, R32...R3n. Here, the intermediate teaching point group R11, R12...R1n, which has a small amount of interference (close to 0), has the best evaluation value.

Note that other methods may be adopted for evaluating the trajectories corresponding to the intermediate teaching point group Ri1, Ri2, . . . Rin (i = 1 to N) for purposes other than avoiding interference with the obstacle Ob.

In step S108, the intermediate teaching point groups P1, P2, ...Pn are moved based on the evaluation values of the N intermediate teaching point groups Ri1, Ri2, ...Rin (i = 1 to N) (FIG. 5(e)) ). One method of this movement is, for example, to move the intermediate teaching points to the intermediate teaching point group with the lowest (favorable) evaluation value among the intermediate teaching point groups Ri1, Ri2,...Rin (i = 1 to N). A possible method is to move the groups P1, P2, . . . Pn. In the example of FIG. 5(e), the intermediate teaching point groups P1, P2, ...Pn (in the first intermediate teaching point group) are located at the positions of the intermediate teaching point groups R11, R12...R1n, where the amount of interference is small (close to 0). is being moved.

In addition, the weights of the N intermediate teaching point groups Ri1, Ri2, ... Rin (i = 1 to N) are calculated using the reciprocal of the evaluation value of the intermediate teaching point group Ri1, Ri2, ... Rin (i = 1 to N). Alternatively, a method may be used in which the intermediate teaching point group P1, P2, . . . , Pn is moved.

In step S109, it is determined whether the conditions for aborting the processes from step S102 to step S108 are satisfied. If the abort condition is not met, the process returns to step S102, and if the abort condition is met, the process proceeds to step S110.

Alternatively, an upper limit number of times to execute the loop from step S102 to step S109 may be determined. In this case, if the upper limit has been reached in step S109, further attempts are given up and the process proceeds to step S110. Alternatively, error handling may be performed such as outputting an appropriate error message on the display unit 4.

The discontinuation condition determined in step S109 is, for example, to generate the same evaluation value as in step S107 for the intermediate taught point group P1, P2,...Pn (first intermediate taught point group) after the movement, and the evaluation value is The condition is that a predetermined condition is met. For example, the purpose of this embodiment is to avoid interference between the robot arm A and the obstacle Ob. Therefore, it is assumed that the evaluation value generated for the intermediate teaching point group P1, P2, . This makes it possible to generate an optimal trajectory that satisfies the constraints regarding robot motion (trajectory determination step).

In step S110, intermediate teaching point groups P1, P2, . . . Pn are output as optimized teaching points. This output can be obtained by, for example, operating a 3D model of the robot arm A (robot arm model) on a trajectory generated by the optimized intermediate teaching point group P1, P2, ...Pn within the virtual display of the display unit 4. conduct. Alternatively, step S110 is a process of outputting the intermediate teaching point group P1, P2,...Pn optimized for the actual robot arm A or its robot control device (200: FIG. 10) or the trajectory data generated thereby. There may be.

In this embodiment, since the purpose is to avoid interference, when reaching step S110, as shown in FIG. 6, the trajectory (p1, p2,... ...pt), the robot arm is in a state where it does not interfere with the interfering object.

According to the present embodiment, a plurality of intermediate taught point groups Ri1, Ri2, ... Rin (i = 1 to N) are generated, and based on the results of evaluating the trajectory defined thereby, intermediate taught point groups P1, P2 are generated. ,...Move Pn. Conditions related to physical constraints such as joint torque constraints are used to evaluate the trajectory, and conditions for achieving obstacle avoidance are used as escape conditions for the process of moving the intermediate teaching point group P1, P2, . . . Pn. With such a configuration, according to the present embodiment, it is possible to generate a smooth curved trajectory that avoids obstacles and satisfies physical constraints such as joint torque constraints.

<Embodiment 2>
Hereinafter, with reference to FIG. 7, an example of optimization processing for generating a trajectory in which the robot arm A (3D model thereof) can avoid interference with the obstacle Ob and can move in the shortest time will be described. It is assumed that configurations other than those in FIG. 7, such as the hardware configuration of the trajectory generation device and its control device, are the same as in the first embodiment.

The control procedure of the trajectory generation method of this embodiment is equivalent to the flowchart of FIG. The values, trajectory constraint methods, trajectory evaluation methods, and censoring conditions are different. FIG. 7 shows how the trajectory (first intermediate teaching point) is optimized in this embodiment. FIG. 7 shows, in the same format as FIG. 5, the processing of each step in FIG. 4 in this embodiment.

In the first embodiment described above, in step S101 in FIG. 4, intermediate teaching point groups P1, P2, ... Pn are generated by path planning technology between the start teaching point Ps and the target teaching point Pg (FIG. 7(a)). An example was given. In contrast, in this embodiment, the intermediate teaching point group P1, P2,...Pn (FIGS. 6 and 7(b)) outputted through the optimization process of Embodiment 1 in step S101 of FIG. 4 is used. .

By setting the intermediate teaching point group P1, P2, ...Pn, which has already been output through the optimization process of the first embodiment, as an initial value, it is possible to perform optimization to shorten the operation time of a trajectory that has already avoided an obstacle. can. In this way, the optimization control procedure of the present invention (FIG. 4) can be used in two passes (or more than one pass), and in that case, by applying different constraint conditions in each pass, each A trajectory optimized for constraints can be obtained.

In the first embodiment, a new intermediate teaching point group R1, R2,...Rn (second intermediate teaching point group) is generated (FIG. 5(c)), and in step S104 of FIG. When determining whether the trajectory of the point group satisfies the constraints, it is determined whether it is within the movable range of the robot arm A. In this embodiment, a new group of intermediate teaching points R1, R2,...Rn (second intermediate teaching point group) is generated (FIG. 7(c)), and in addition to determining whether or not the robot arm is within the movable range, It is determined whether or not A is interfering with the obstacle Ob. If there is interference with an obstacle, the intermediate taught point group R1, R2, . . . Rn is invalidated and the process returns to step S102.

Furthermore, in the first embodiment, in step S107 in FIG. 4, the trajectory is evaluated using the interference time or the amount of penetration as an evaluation value. In this embodiment, the trajectory is evaluated using the operation time of the robot arm A as an evaluation value (FIG. 7(d)). Thereby, it is possible to generate intermediate teaching point groups P1, P2, . . . Pn with the shortest operation time. In the example of FIG. 7(d), the evaluation values of the second intermediate teaching point group related to the operation time are 180 for R11, R12...R1n, 120 for R21, R22...R2n, and 150 for R31, R32...R3n. It has become. Here, the intermediate teaching point group R21, R22, . . . R2n, which has a small amount of interference (has a small operation time value), has the best evaluation value.

Furthermore, in the first embodiment, one of the termination conditions in step S109 in FIG. 4 is that the evaluation value becomes 0. On the other hand, in the present embodiment, a method is adopted in which an upper limit is set for the number of repetitions from step S102 to step S109, or the evaluation value of the intermediate teaching point group P1, P2,...Pn is set to a number of consecutive times (almost) unchanged. Use a method that sets an upper limit. For example, if the operation time cannot be further shortened, the loop from step S102 to step S109 is exited, and the intermediate teaching point group P1, P2, ... Pn that provides the shortest time is output in step S110 (FIG. 7(e)) ). Alternatively, in the second embodiment, the group of intermediate teaching points P1, P2, . . . Pn in the final movement state does not necessarily have to be output as the optimized teaching points in step S110. For example, the history of changes in the group of intermediate teaching points P1, P2, .

As described above, the present embodiment has the advantage that it is possible to generate a trajectory that minimizes the operating time while avoiding obstacles and observing physical constraints such as torque constraints. In particular, the optimization control procedure (Figure 4) can be used in two passes (or more than one pass), in which case the optimization for each constraint is achieved by applying different constraints in each pass. It is possible to obtain the trajectory.

Here, a more specific example of the configuration of the robot arm A and a configuration when the robot arm A is applied to a production system will be shown.

FIG. 10 shows a more specific overall configuration of the robot arm A than the schematic configuration shown in FIG. In FIG. 10, a robot arm A (robot device) includes a vertically articulated arm body 201 with, for example, six axes (joints). Each joint of the arm body 201 can be controlled to a desired position and orientation by servo-controlling a servo motor provided at each joint.

A tool such as a hand 202 is attached to the tip (hand) of the arm body 201, and the hand 202 can grip a workpiece 203 and perform production work such as assembling or processing the workpiece 203. can. The workpiece 203 is, for example, a part of an industrial product such as an automobile or an electrical appliance, and the robot arm A can be placed as a production device in such a production system (production line).

The operation of the arm body 201 of the robot arm A is controlled by a robot control device 200 (robot controller). The operation of the robot arm A can also be programmed (taught) by an operation terminal 204 (for example, a teaching pendant) connected to the robot control device 200. For example, by sequentially specifying teaching points using the operation terminal 204, it is possible to program an operation that moves a specific part of the robot arm A (eg, TCP: tool mounting surface at the tip of the arm, etc.) along a desired trajectory.

Further, via the network NW, the robot arm A or the robot control device 200 receives intermediate teaching points or trajectory data optimized as described above from the trajectory generation device (or robot simulator: FIG. 1). be able to. Thereby, based on the intermediate teaching point or trajectory data optimized through the above processing, the robot arm A can be placed in the production system (production line), operated as a production device, and manufactured articles.

The present invention provides a program that implements one or more of the functions of the embodiments described above to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device reads and executes the program. This can also be achieved through processing. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

A...Robot arm, J1, J2...Joint axis, Ob...Obstacle, Ps...Start teaching point, Pg...Target teaching point, P1, P2,...Pn...(First) intermediate teaching point group, Ri1, Ri2, Rin... (second) intermediate teaching point group, 1... Arithmetic processing section, 2... Operation section, 3... Recording section, 4... Display section.

Claims (38)

In an information processing method for acquiring a trajectory for operating a robot arm between a first position and a second position,
an intermediate trajectory obtaining step of setting at least two intermediate teaching point groups that define a route from the first position to the second position, and obtaining at least two intermediate trajectories based on the intermediate teaching point groups;
an evaluation step of acquiring an evaluation value on the intermediate trajectory acquired in the intermediate trajectory acquisition step;
a trajectory obtaining step of obtaining a trajectory for operating the robot arm based on a predetermined intermediate trajectory among the intermediate trajectories based on the evaluation value;
An information processing method characterized by: In the information processing method according to claim 1,
In the trajectory acquisition step, the predetermined intermediate trajectory is selected from among the intermediate trajectories based on the evaluation value.
An information processing method characterized by: The information processing method according to claim 1 or 2,
In the intermediate trajectory acquisition step, the at least two intermediate teaching point groups are set by applying different displacements to intermediate teaching points included in a predetermined intermediate teaching point group.
An information processing method characterized by: In the information processing method according to claim 3,
In the intermediate trajectory acquisition step, the displacement is given by adding a value to the intermediate teaching point, and the at least two intermediate teaching point groups are set.
An information processing method characterized by: In the information processing method according to claim 3 or 4 ,
The displacement is given based on correlated random numbers,
An information processing method characterized by: In the information processing method according to claim 5,
The intermediate teaching points are adjacent to each other, and in the intermediate trajectory obtaining step, the displacement is applied to the adjacent intermediate teaching points based on the random number.
An information processing method characterized by: In the information processing method according to claim 5 or 6 ,
Correlating the random numbers by assigning a positive value to the covariance in the variance-covariance matrix;
An information processing method characterized by: The information processing method according to any one of claims 1 to 7 ,
In the intermediate trajectory acquisition step, the intermediate trajectory that satisfies physical constraints regarding the drive mechanism of the robot arm is acquired;
An information processing method characterized by: The information processing method according to claim 8 ,
The constraint condition is a movable range of the robot arm.
An information processing method characterized by: The information processing method according to claim 8 or 9 ,
The constraint condition is any one or more of a joint torque constraint, a joint angular velocity constraint, a joint angular acceleration constraint, a jerk constraint, a hand speed constraint, or a hand acceleration constraint regarding the robot arm.
An information processing method characterized by The information processing method according to any one of claims 8 to 10 ,
In the evaluation step, the evaluation value is obtained based on the amount of interference between the robot arm and an object placed in a space in which the robot arm operates in the intermediate trajectory.
An information processing method characterized by: The information processing method according to claim 11 ,
The amount of interference is an interference time or an interference distance in which the robot arm and an object placed in the space in which the robot arm operates occupy the same space.
An information processing method characterized by: The information processing method according to claim 11 or 12 ,
In the intermediate trajectory acquisition step, if the constraint condition is satisfied, a predetermined intermediate trajectory in which interference occurs between the robot arm and the object is also acquired as the at least two intermediate trajectories.
An information processing method characterized by: The information processing method according to any one of claims 11 to 13 ,
In the trajectory acquisition step, if the amount of interference is 0, it is determined that no interference has occurred between the robot arm and the object;
An information processing method characterized by: The information processing method according to any one of claims 1 to 14,
One intermediate teaching point group among the at least two intermediate teaching point groups can be set by a user via a user interface;
An information processing method characterized by: The information processing method according to any one of claims 1 to 15 ,
repeating the intermediate trajectory acquisition step, the evaluation step, and the trajectory acquisition step;
An information processing method characterized by: The information processing method according to any one of claims 1 to 10 ,
In the intermediate trajectory acquisition step, the at least two intermediate trajectories are acquired such that the operation time for operating the robot arm is shortened.
An information processing method characterized by: The information processing method according to any one of claims 1 to 10 ,
In the evaluation step, the evaluation value is obtained based on the operation time when the robot arm is operated in the at least two intermediate trajectories.
An information processing method characterized by: The information processing method according to any one of claims 1 to 18 ,
In the trajectory acquisition step, the acquisition of the trajectory for operating the robot arm is stopped on the condition that the evaluation value satisfies a predetermined condition.
An information processing method characterized by: In the information processing method according to claim 19 ,
The predetermined condition is a case where it is determined that the evaluation value has not changed even after performing acquisition of a trajectory for operating the robot arm a predetermined number of times.
An information processing method characterized by: The information processing method according to any one of claims 1 to 20 ,
stopping the acquisition of the trajectory for operating the robot arm based on the number of repeated executions of acquisition of the trajectory for operating the robot arm reaching a predetermined number of times;
An information processing method characterized by: The information processing method according to any one of claims 1 to 21 ,
In the intermediate trajectory acquisition step, the at least two intermediate trajectories are acquired using at least one of the potential method, PRM, RRT, visible graph method, cell division method, and Voronoi diagram.
An information processing method characterized by: The information processing method according to any one of claims 1 to 22 ,
In the intermediate trajectory acquisition step, smoothing the at least two intermediate trajectories using at least one of Spline interpolation, B-Spline interpolation, and Bezier curve interpolation.
An information processing method characterized by: The information processing method according to any one of claims 1 to 23 ,
further comprising a display step of displaying the trajectory for operating the robot arm acquired in the trajectory acquisition step on a display device;
An information processing method characterized by: The information processing method according to any one of claims 1 to 24 ,
further comprising an output step of outputting the trajectory for operating the robot arm acquired in the trajectory acquisition step to a control device that controls the robot arm;
An information processing method characterized by: The information processing method according to any one of claims 1 to 25 ,
In the trajectory acquisition step, a trajectory for operating the robot arm is updated based on the predetermined intermediate trajectory.
An information processing method characterized by: The information processing method according to any one of claims 1 to 26 ,
further comprising a reception step of accepting the setting of the first position or the second position;
An information processing method characterized by: The information processing method according to any one of claims 1 to 10,
a determination step of determining whether or not the robot arm and an object placed in a space in which the robot arm operates interfere in the at least two intermediate trajectories acquired in the intermediate trajectory acquisition step;
In the evaluation step, an operation time for operating the robot arm in an intermediate trajectory in which it is determined in the determination step that there is no interference between the robot arm and an object placed in the space in which the robot arm operates. obtaining the evaluation value regarding;
An information processing method characterized by: The information processing method according to claim 28,
In the determination step, intermediate trajectories for which it is determined that interference between the robot arm and an object placed in the space in which the robot arm operates is invalidated so as not to be evaluated in the evaluation step. do,
An information processing method characterized by: The information processing method according to claim 1 or 2,
In the intermediate trajectory acquisition step,
Setting a first intermediate teaching point group and a second intermediate teaching point group as the at least two intermediate teaching point groups,
The first intermediate teaching point group defines a path from the first position to the second position in which the robot arm and an object placed in a space in which the robot arm operates can avoid interference;
obtaining the second intermediate teaching point group by displacing the first intermediate teaching point group, and obtaining the at least two intermediate trajectories based on the second intermediate teaching point group;
An information processing method characterized by: The information processing method according to claim 30,
setting the first intermediate teaching point group by a track planning algorithm;
An information processing method characterized by: The information processing method according to claim 30 or 31,
In the trajectory acquisition step, the first intermediate teaching point group is moved to the second intermediate teaching point group corresponding to the predetermined intermediate trajectory, and based on the moved first intermediate teaching point group, the robot arm Obtain the trajectory to operate,
An information processing method characterized by: A program that causes a computer to execute each step of the information processing method according to claim 1. A computer-readable recording medium storing the program according to claim 33 . In an information processing device that obtains a trajectory for operating a robot arm between a first position and a second position,
setting at least two intermediate teaching point groups that define a route from the first position to the second position, obtaining at least two intermediate trajectories based on the intermediate teaching point group;
obtaining an evaluation value in the obtained intermediate trajectory;
obtaining a trajectory for operating the robot arm based on a predetermined intermediate trajectory among the intermediate trajectories based on the evaluation value;
An information processing device characterized by: A production system that assembles workpieces by operating the robot arm on a trajectory obtained using the information processing method according to claim 1 to manufacture articles. A robot system comprising the robot arm whose motion is controlled based on a trajectory acquired using the information processing method according to any one of claims 1 to 32 . 33. A method for manufacturing an article, comprising assembling a workpiece by operating the robot arm on a trajectory obtained using the information processing method according to any one of claims 1 to 32 , and manufacturing the article.

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