JP7348001B2 - robot simulation device - Google Patents

Description

The present invention relates to a robot simulation device for a robot system.

2. Description of the Related Art Robot systems are known that handle workpieces placed on a workpiece transfer device or stacked in bulk. In such a robot system, it is necessary to teach the robot (namely, the hand) the position at which to grip the workpiece. Patent Document 1 states, ``The X coordinate of the gripping position is displayed on an and an X-Y specifying section for specifying the X-coordinate and Y-coordinate of the gripping position, and the Z-coordinate and Z of either or both of the workpiece model or the end effector model for which the X-coordinate and Y-coordinate of the gripping position are specified in the X-Y specifying section. A Z-R _{Z part} for specifying the R Z angle around the axis, and either or both of the work model or end effector model in which the Z coordinate of the gripping position and the R _Z angle are specified in the Z-R _Z part. R _X -R Y specification section, _X - _Y specification section, Z- _{R Z specification} section for specifying the R , R _X -R _Y designation section, and a grip position storage section for storing the grip position of the workpiece model or end effector model designated by the R X -R Y designation section (Patent Document 1, abstract).

Patent Document 2 describes a method for generating a robot grasping pattern that includes the step of generating a plurality of approach rays related to a target object, each of the plurality of approach rays extending perpendicularly from a surface of the target object. The method further comprises: generating at least one grasping pattern for each approach ray of the plurality of approach rays, and for each individual grasping pattern of the set of grasping patterns, to generate grasping patterns of the target object associated with the plurality of approach rays. The method further includes calculating a grasp quality score and comparing the grasp quality score of each individual grasp pattern with a grasp quality threshold. and a step of supplying the selected gripping pattern to a robot for online manipulation of a target object.'' (Patent Document 2, Abstract).

Japanese Patent Application Publication No. 2018-144162 Japanese Patent Application Publication No. 2013-144355

Generally, it is difficult to accurately teach the gripping position of a workpiece by the hand, and adjustments may be required on site. There is a need for a device that can automatically provide accurate teaching of the gripping position of a workpiece by a hand.

One aspect of the present disclosure provides a model data storage unit that stores a hand model and a workpiece model that are model data of a hand and a workpiece, a grasping form of the workpiece model by the hand model, and an approach direction of the hand model with respect to the workpiece model. and a gripping condition input unit that receives an input regarding a gripping part at which the hand model grips the workpiece model, and a gripping condition input unit that allows the hand model to approach the workpiece model in a virtual space using the hand model and the workpiece model. The hand model can move along the approach direction from a first position for starting to a second position where the hand model can grip the gripping portion of the workpiece model without interfering with the workpiece model. a hand position/posture determining unit that determines the first position and the second position; a teaching point adding unit that adds the first position and the second position as teaching points to a robot operation program; and the second position. a grasping simulation execution unit that causes a grasping operation to close the fingers of the hand model in a simulated manner, and stops the grasping operation when it is detected that the fingers come into contact with the workpiece model. It is a device.

According to the above configuration, the robot (hand) can automatically teach accurate grasping motion.

These and other objects, features and advantages of the invention will become more apparent from the detailed description of exemplary embodiments of the invention, which are illustrated in the accompanying drawings.

FIG. 1 is a block diagram showing the configuration of a simulation device according to an embodiment. 3 is a flowchart illustrating the flow of hand position and posture determination processing. It is a figure showing the 1st example of a grip form. It is a figure showing the 2nd example of a grip form. It is a figure showing the 3rd example of a grip form. It is a figure showing the 4th example of a grip form. FIG. 6 is a diagram illustrating a first example of specifying an approach direction and a gripping part. FIG. 7 is a diagram illustrating a second example of specifying an approach direction and a gripping part. FIG. 7 is a diagram showing a third example of specifying an approach direction and a gripping part. It is a figure showing the 4th example of designation of an approach direction and a grip part. FIG. 6 is a diagram illustrating a simulation operation of movement of a hand between an approach position and a grasping position. FIG. 3 is a diagram illustrating the operation of a gripping simulation. FIG. 6 is a diagram illustrating the operation of a soft hand grip simulation. FIG. 2 is a diagram illustrating a configuration example of a robot system to which a robot operation program in which an approach position and a grip position are reflected as teaching points by a simulation device is applied. FIG. 3 is a diagram for explaining parameters for determining hand specifications. FIG. 6 is a diagram for explaining the specifications of a hand to be determined. FIG. 4 is a diagram for explaining determination of the size of the claw portion of the hand. FIG. 3 is a diagram for explaining deflection that occurs in a beam. It is a figure showing the form which grasps the 1st part of a work. It is a figure showing the form which grasps the 2nd part of a work. It is a figure showing the form which grasps the 3rd part of a work. FIG. 3 is a diagram illustrating an example of randomly generated positions and postures of workpieces. 14A is a diagram illustrating a state in which the workpiece in FIG. 14A is gripped by a hand. FIG.

Next, embodiments of the present disclosure will be described with reference to the drawings. In the drawings referred to, like components or functional parts are provided with like reference numerals. For ease of understanding, the scale of these drawings has been changed accordingly. Moreover, the form shown in the drawings is one example for implementing the present invention, and the present invention is not limited to the form shown in the drawings.

FIG. 1 is a block diagram showing the configuration of a robot simulation device 90 (hereinafter referred to as simulation device 90) according to an embodiment. For example, the simulation device 90 automatically generates the gripping position of the workpiece by the robot (hand) using predetermined parameters related to the gripping conditions of the robot hand (hereinafter simply referred to as hand) input by the user. This is a so-called offline programming device that reflects the robot operation program. This allows the robot (hand) to automatically teach an accurate grasping operation in the form intended by the user.

As shown in FIG. 1, the simulation device 90 includes, for example, a memory 20 (ROM, RAM, etc.), a storage device 30 such as an HDD, a display unit 40 including a display, an operation unit 50 (keyboard, (pointing device, etc.), a communication interface 60, etc., are connected to each other via a bus line. The simulation device 90 may be, for example, various information processing devices such as a desktop PC, a laptop PC, a tablet terminal, or a portable information terminal.

The simulation device 90 further includes a grip condition input section 11 , a hand position/posture determination section 12 , a teaching point addition section 13 , a grip simulation execution section 14 , a grip form registration section 15 , and a hand specification determination section 16 . The gripping condition input unit 11 receives input of gripping conditions by the user via a user interface implemented by the display unit 40 and the operation unit 50. The hand position and orientation determination unit 12 determines the position and orientation of the hand for the hand to perform an appropriate gripping operation using the gripping conditions input by the user. The teaching point addition unit 13 reflects the position and orientation of the hand determined by the hand position and orientation determining unit 12 as teaching points in the robot operation program in which the hand is mounted. The storage device 30 stores model data 31 (robot model, hand model, workpiece model, etc.) of a robot, various hands, various workpieces, and the like. The gripping simulation execution unit 14 uses the model data 31 of the hand and the like stored in the storage device 30 to execute a simulation of an operation in which the hand closes its claws and grips a workpiece. Below, for convenience of explanation, a robot model, a hand model, and a workpiece model may be referred to simply as a robot, a hand, and a workpiece.

In FIG. 1, the grip condition input unit 11, hand position/posture determination unit 12, teaching point addition unit 13, grip simulation execution unit 14, grip form registration unit 15, and hand specification determination unit 16 are stored in the storage device 30 by the CPU 10. Although the present invention is described as being a function realized by executing various types of software, the present invention is not limited to such a configuration. For example, these functional units may be realized by a configuration mainly composed of hardware such as an ASIC (Application Specific Integrated IC). The simulation device 90 may be connected to a robot control device via the communication interface 60, for example, and the robot operation program generated by the simulation device 90 may be provided to the robot control device via the communication interface 60.

FIG. 2 is a flowchart showing the flow of hand position and posture determination processing. In the hand position/orientation determination process according to the present embodiment, grip conditions are determined based on three parameters: a gripping form, an approach direction indicating the direction in which the hand approaches the workpiece, and a gripping part of the workpiece in the virtual space. , the hand model interferes with the workpiece along the approach direction from the first position (approach position) where the hand starts approaching the workpiece to the second position (grip position) where the hand can grip the gripping part of the workpiece. The approach position and grasping position are determined so that the object can be moved without any movement. Note that the approach position and grasping position also include the posture of the hand. The hand position and posture determination process is realized by the CPU 10 of the simulation device 90 executing the hand position and posture determination program 32 stored in the storage device 30.

First, the simulation device 90 (gripping condition input unit 11) receives a selection of a gripping form (step S11). FIGS. 3A to 3D show four examples of grip forms selected and input by the user in step S11. FIG. 3A is a diagram schematically showing a gripping mode (hereinafter referred to as outer diameter gripping) in which the gripping portion of the workpiece is gripped from the outside. As shown in FIG. 3A, in the case of outer diameter gripping, for example, the workpiece W1 is gripped from the outside using a hand H1 having a parallel-moving claw portion. FIG. 3B is a diagram schematically illustrating a gripping mode (hereinafter referred to as inner diameter gripping) in which a workpiece is held by pressing a claw against a hole in the workpiece from the inside. As shown in FIG. 3B, in the case of inner diameter gripping, for example, the hand H2 having a parallel movement type claw is used to press the claw against the inner peripheral surface of the hole of the workpiece W2. Hold W2.

FIG. 3C is a diagram schematically showing a gripping mode for scooping up a workpiece (hereinafter referred to as scooping up). In the case of scooping up, as shown in FIG. 3C as an example, a hand H3 having an L-shape in longitudinal section is used to lift and hold the workpiece W3 from below. FIG. 3D is a diagram schematically showing a gripping form by suction. As shown in FIG. 3D, in the case of suction, a suction type hand H4 is used to suction and lift the workpiece W4. Note that in this specification, the operation of holding a workpiece with a hand, including outer diameter gripping, inner diameter gripping, scooping up, and suction as shown in FIGS. 3A to 3C, is sometimes referred to as gripping.

In selecting a grip form in step S11, the simulation device 90 displays an icon image schematically representing a grip form as shown in FIGS. 3A to 3D, and accepts selection of a grip form by a selection operation on the icon image. You can do it like this. Selection of the grip form corresponds to selection of the type of hand to be used. Therefore, the simulation device 90 may determine the type of hand to be used in the operation confirmation from step S12 onwards, based on the selection result of the grip form at step S11.

In step S12, the simulation device 90 (grip condition input unit 11) receives the designation of the approach direction. Further, in step S13, the simulation device 90 (gripping condition input unit 11) receives the designation of the gripping region. FIG. 4A is a diagram illustrating an example of specifying the approach direction and the gripping region when outer diameter gripping is selected as the gripping mode. As an example, the simulation device 90 may display an image of the workpiece W as shown in FIG. 4A on the display unit 40 using model data of the workpiece W, and may receive designation of the approach direction and the gripping part on the image. . In the example of FIG. 4A, the vicinity of the center in the vertical direction of the side surface of the upper portion 112 of the workpiece W is designated as the gripping portions M1 and M2. Further, as the approach direction, a direction from the upper surface of the upper part 112 of the work W to the upper side is designated as the approach direction D1. Note that the approach direction may be specified as representing the direction from which the hand approaches when viewed from the workpiece, as shown in the figure. The simulation device 90 may be configured to accept designation of the gripping region and approach direction using a circular (or elliptical) frame line or an arrow mark as shown in FIG. 4A. When the approach direction D1 and the gripping parts M1 and M2 are specified as shown in FIG. 4A, the simulation device 90 causes the hand to approach the workpiece W from above and grips the gripping parts M1 and M2 with the claws of the hand. The approach position and grasping position are determined so as to cause the movement to be performed.

FIG. 4B is a diagram illustrating an example of specifying the approach direction and the gripping region when inner diameter gripping is selected as the gripping mode. As an example, the simulation device 90 may display an image of the workpiece W2 as shown in FIG. 4B using the model data of the workpiece W2, and may receive designation of the approach direction and the gripping part on the image. In the example of FIG. 4B, the hole 121 of the workpiece W2 is designated as the gripping portion M3, and the direction upward from the bottom surface of the hole 121 is designated as the approach direction D2. The simulation device 90 may accept designation of the gripping region and approach direction using a circular (or elliptical) frame line or an arrow mark as shown in FIG. 4B. When the approach direction D2 and the gripping part M3 are specified as shown in FIG. 4B, the simulation device 90 causes the hand to approach the workpiece W2 from above and presses the claw portion of the hand against the inner peripheral surface of the hole 121. The approach position and the gripping position are determined so that the workpiece W2 can be gripped.

FIG. 4C is a diagram illustrating an example of specifying an approach direction and a gripping part when scooping up is selected as the gripping mode. As an example, the simulation device 90 may display an image of the workpiece W3 as shown in FIG. 4C, and may receive designation of the approach direction and the gripping part on the image. In the example of FIG. 4C, the bottom surface 131 of the workpiece W3 is designated as the gripping portion M4, and the direction toward the right from the right side surface of the workpiece W3 is designated as the approach direction D3. The simulation device 90 may accept designation of the gripping region and approach direction using a circular (or elliptical) frame line or an arrow mark as shown in FIG. 4C. When the approach direction D3 and the gripping part M4 are specified as shown in FIG. 4C, the simulation device 90 places the hand on the workpiece W3 from above to the right side of the workpiece W3, and then moves the hand to the right side of the workpiece W3. The approach position and gripping position are determined so that the workpiece W3 is approached and held from the right side of the workpiece W3. In the case of this example, two approach positions may be set: a position above the workpiece W3 and a position on the right side of the workpiece W3.

FIG. 4D is a diagram illustrating an example of specifying an approach direction and a gripping part when suction is selected as the gripping mode. As an example, the simulation device 90 may display an image of the workpiece W4 as shown in FIG. 4D, and may receive designation of the approach direction and the gripping region on the image. In the example of FIG. 4D, the upper surface 141 of the workpiece W4 is designated as the gripping portion M5, and the direction upward from the upper surface 141 is designated as the approach direction D4. The simulation device 90 may accept designation of the gripping region and approach direction using a circular (or elliptical) frame line or an arrow mark as shown in FIG. 4D. When the approach direction D4 and the gripping part M5 are specified as shown in FIG. 4D, the simulation device 90 causes the hand to approach the workpiece W4 from above and to hold the upper surface 141 of the workpiece W4 by suction. The approach position and grasping position are determined.

Next, in step S14, the simulation device 90 (hand position/orientation determining unit 12) determines an approach position and a gripping position as positions where the hand and the workpiece do not interfere with each other. FIG. 5 is a diagram illustrating the simulation operation executed by the simulation device 90 in step S14. Here, a case will be described in which the outer diameter grip is selected as the grip type and the approach direction and grip portion are designated as shown in FIG. 4A. The simulation device 90 determines a gripping position P 01 as a temporary position where the gripping parts M1 and M2 of the workpiece W can be gripped, and also determines a gripping position P ₀₁ which is a position along the approach direction D1 and changes the gripping position P 01 by one movement command of the robot. A temporary approach position P ₀₂ is determined as a position that can be moved to P ₀₁ . The gripping position P ₀₁ may be determined as a position where the part 112 of the workpiece W is placed at the center position between the two claws 211 and 212 (gripping space) of the hand H1.

Next, the simulation device 90 uses the model data of the workpiece W and the hand H1 to execute a simulation in which the hand H1 model is moved between the approach position P ₀₂ and the gripping position P ₀₁ with respect to the workpiece W model. Specifically, the simulation device 90 places a model of the workpiece W in the illustrated posture at a predetermined position in the virtual space, and simulates the model of the hand H1 between the approach position P ₀₂ and the grasping position P ₀₁ . move it to At this time, the simulation device 90 checks whether there is any interference between the model of the workpiece W and the model of the hand H1. If interference occurs, the positions of the temporary gripping position P ₀₁ and the temporary approach position P ₀₂ are adjusted to prevent interference. When it is confirmed that there will be no interference with the workpiece W when the model of the hand H1 is moved between the temporary gripping position _P01 and the temporary approach position _P02 , the simulation device 90 The position P ₀₁ and the tentative approach position P ₀₂ are adopted as the formal gripping position P ₁₁ and the approach position P ₁₂ (see the right side of FIG. 5).

Note that the approach position and the gripping position may be generated as positions representing TCP (Tool Center Point). In addition, the approach position and gripping position are generated as coordinates in virtual space, but these are applied as positions in real space based on the position information of the workpiece in real space (robot coordinate system), for example. can do.

Next, the simulation device 90 adds the grasping position P ₁₁ and the approach position P ₁₂ determined in step S14 to the teaching points for the robot, thereby reflecting them in the robot operation program (step S15). Through the above processing, automation of the teaching of the workpiece gripping operation by the robot is realized.

The simulation device 90 (gripping simulation execution unit 14) is configured to confirm that the workpiece W can be gripped correctly by causing the model of the hand H1 to perform a simulated closing action of the claws 211 and 212 at the gripping position. (Step S16). Specifically, the simulation device 90 places the model data of the hand H1 at the gripping position, closes the claws 211 and 212 (see the left side of FIG. 6), and brings the claws 211 and 212 into contact with the model of the workpiece W. By the way, stop it (see the right side of FIG. 6). By performing this operation, the simulation device 90 confirms that the workpiece W can be correctly gripped within the stroke range of the hand H1. Note that if a problem such as the inability to grip the workpiece W within the stroke range of the hand H1 is found, the gripping position may be adjusted and then the process from step S14 may be executed again. This makes it possible to teach more accurate gripping motions.

A simulation of a grasping motion by the grasping simulation execution unit 14 when the hand is a so-called soft hand made of a flexible material will be described with reference to FIG. The left side of FIG. 7 shows the configuration of hand H6 configured as a soft hand. As shown on the left side of FIG. 7, the hand H6 includes fingers 161 and 162 made of a flexible material such as silicone resin, and a support portion 160 that supports the fingers 161 and 162. The fingers 161 and 162 are configured to curve in a predetermined direction and grip an object by injecting compressed air, for example. In simulating the grasping motion of such a soft hand, the flexibly curved fingers 161 and 162 are modeled into a multi-jointed structure. As an example, FIG. 7 (see the center part of FIG. 7) shows an example in which the finger 161 is a multi-joint model in which three links 171 to 173 are connected by two joints 181 and 182. The finger 162 is similarly modeled into three links and two joints connecting them.

After performing such modeling, a grasping motion simulation is performed using the following motion rules.
(M1) A state in which the tips of the fingers 161 and 162 are further spread apart from each other than in the state shown in the center part of FIG. 7 is brought into an open state. From this open state, a rotational movement is applied such that the tips of the fingers 161, 162 approach each other around the base end portion where each finger 161, 162 is connected to the support portion 160.
(M2) While performing the movement of (M1) above, it is detected that any of the links 171 to 173 comes into contact with the workpiece, and the movement of the links on the proximal end side including the link for which contact is detected is stopped.
(M3) Continue the operation according to (M1) and (M2) above for the link on the tip side of the link whose contact was detected in (M2) above. These operations (M1) to (M3) are performed until the link at the tip comes into contact with the workpiece.

By performing such an operation, it is possible to move each finger 161, 162 along the workpiece W to simulate an operation of gripping the workpiece W. The right side of FIG. 7 shows the execution results when the multi-joint structure model of the soft hand H1 is caused to perform a gripping operation on the workpiece W according to the above-mentioned operation rule. In this example of operation, the workpiece W is gripped by the links 172 and 173 of the finger 161 (and the two corresponding links of the finger 162). In this way, simulation of grasping motion is realized even in the case of soft hands. As described above, it is possible to reliably execute the soft hand gripping simulation while reducing the calculation load.

FIG. 8 is a diagram illustrating a configuration example of a robot system 500 to which a robot operation program in which the approach position and gripping position are reflected as teaching points by the simulation device 90 is applied. As shown in FIG. 8, the robot system 500 includes a robot 600, a robot control device 510 that controls the robot 600, and a work transfer device 650. The robot 600 is configured as a vertically articulated robot, and a hand H1 is mounted on the tip of the arm, for example. The robot control device 510 also controls the transport operation of the workpiece transport device 650. In this configuration, the robot 600 picks up the workpiece W being transported on the workpiece transport device 650 and transports it to a predetermined position according to the robot operation program.

The robot system 500 is further provided with a vision sensor 550 for detecting the position and orientation of the workpiece W. Vision sensor 550 is connected to robot controller 510. The robot operation program provided from the simulation device 90 to the robot control device 510 reflects the approach position and grasping position determined by the above-described hand position and orientation determination process as teaching points. The robot control device 510 corrects the teaching point (approach position and grasping position) as a position in real space based on the position and orientation of the work W in real space detected by the vision sensor 550, and then The robot performs an approach and grasping operation.

The simulation device 90 may further include a hand specification determination unit 16 that generates hand specifications based on predetermined parameters regarding the shape of the workpiece and the arrangement relationship between the hand and the workpiece at the gripping position. Here, the determination of predetermined parameters and hand specifications will be explained using a parallel movement type hand H1 and workpiece W as shown in FIG. 9 as an example. Note that FIG. 9 is a diagram for explaining parameters for determining hand specifications, and FIG. 10 is a diagram for explaining determined hand specifications. The parameters to be specified are the following five parameters. The hand specification determining unit 16 receives parameter input via a user interface or from an external device.
(P1) Top offset (designated 311 in Figure 9)
(P2) Hand opening offset (designated 312 in Fig. 9)
(P3) Grasping point (designated 313 in Figure 9)
(P4) Grip diameter (designated 314 in Figure 9)
(P5) Work mass

The upper offset 311 is the distance between the lower surface 213a of the support portion 213 that supports the claws 211 and 212 of the claw portion 210 of the hand H1 and the upper surface 112a of the portion 112 that is the gripping portion of the workpiece W. The hand opening offset 312 includes a side surface (for example, the side surface 112b) of the part 112 of the workpiece W and an inner surface (for example, the inner surface 212a) of the claw portion opposite to this side surface when the hand H1 is in the open state of the claw portion 210. ) is the distance between The gripping point 313 is a position inside the portion 112 (typically, approximately the center position or approximately the center of gravity of the portion 112). The grip diameter 314 represents the size of the portion 112 in the opening/closing direction of the claws 211 and 212. For example, when the portion 112 is cylindrical, the gripping diameter 314 is set as the outer diameter of the cylindrical portion 112. The workpiece mass is the mass of the workpiece W. Note that the parameters P1 to P4 can be set based on the gripping position.

The simulation device 90 (hand specification determining unit 16) selects a chuck having a suitable gripping force based on the workpiece mass from among a plurality of types of chucks registered in advance in the storage device 30.
As an example, when performing outer diameter gripping as shown in FIG. 9, the simulation device 90 calculates the necessary gripping force F using the following calculation formula.
n: Number of claws F: Gripping force (N)
μ: Coefficient of friction between the claw and workpiece m: Workpiece mass g: Gravitational acceleration (=9.8N)
mg: Work weight Conditions for preventing the work from falling: n×μF>mg
Therefore, F>mg/(n×μ)
Assuming the safety factor as s _a , the required gripping force is:
F=(s _a ×mg)/(n×μ)
For example, assuming the number of claws n = 2, friction coefficient μ = 0.2, and safety factor a = 4,
F=(mg×4)/(2×0.2)
=10×mg
Therefore, the required gripping force is 10 times the weight of the workpiece. In this case, the simulation device 90 selects a chuck having a gripping force greater than or equal to the required gripping force F. Further, the simulation device 90 can also consider the gripping diameter and other parameters when selecting a chuck having the necessary gripping force. Further, the simulation device 90 can select a chuck having a necessary stroke based on the hand opening offset, gripping diameter, and the like.

Next, the simulation device 90 (hand specification determining unit 16) determines the inner dimensions of the hand based on the parameters P1-P3 (see FIG. 10). As shown in FIG. 10, the inner dimensions of the hand are, for example, the width b1 of the support portion 213 in the gripping direction (opening/closing direction of the claws) in the gripping space of the hand, and the length a1 of the claws 211 and 212 in the protruding direction. May be determined. As an example, the length a1 of the claws 211 and 212 can be set to be longer than the sum of the upper offset 311 and the length between the upper surface 112a of the workpiece W and the gripping point 313. Further, the width b1 of the support portion 213 in the grip direction can be set to be larger than the sum of twice the hand opening offset 312 and the grip diameter 314.

Next, the simulation device 90 (hand specification determining unit 16) determines the size and shape of the claw portion 210 by calculating the strength from the gripping force F of the selected chuck.
Assume that the hand H1 is of the parallel movement type shown in FIG. 11 and has two claws 211 and 212. Specify the dimensions of the cross-sectional area (vertical and horizontal) of the member and calculate the deflection and strain as long as they are within the allowable range.
The deflection δ generated in the beam in the situation shown in FIG. 12 is expressed by the following equation (1).

δ=Wl ₂ ² (3l ₁ +2l ₂ )/(6EI)...(1)
Here, W: Load l: Length of the beam (The length from the support point to the position where the load is applied is _l2 , and the length from the position where the load is applied to the tip is _l1 .)
E: Longitudinal elastic modulus (Young's modulus)
I: Second moment of area

In the situation illustrated in FIG. 11, assuming that the gripping force F is applied to the illustrated position of the claw 212, the deflection δ of the claw 212 is calculated by setting W=F in equation (1). The moment of inertia of area is expressed as bh ³ /12, for example, where b is the width and h is the height of a rectangular cross-sectional shape.

Next, the strain ε of the support part 213 in a situation where the gripping force F acts on the support part 213 in the gripping direction is calculated. The stress σ when a load F is applied in the length direction of the cross-sectional area A length L member is:
σ=F/A
It is expressed as
In this case, the strain ε and the amount of change ΔL in the longitudinal direction of the member are expressed as follows.
ε=σ/E
ΔL=L×ε
According to the above calculation formula, it is sufficient that the amount of change in the strain or length of the support part 213 when the gripping force F is applied to the support part 213 is within an allowable value.

The bolt 271 connecting the check and the support part 213 is selected by setting the maximum load to be equal to or greater than the gripping force x the safety factor. Further, the bolts 272 that connect the support portion 213 and the claws 212 are selected by setting the shear strength to be greater than or equal to the gripping force F×safety factor.

Through the above calculations, the chuck of the hand is selected, and the specifications including the inner dimension 403, shape, size, etc. of the claw portion 210 to be attached to the chuck are determined. In addition, when selecting a chuck and determining the size of the claw portion, it is desirable to select and determine a structure that is as compact as possible while satisfying necessary conditions (gripping force, length, etc.). Note that the hand used in the hand position and orientation determination process described above may be determined according to the hand specifications determined above.

The optimal gripping form for the workpiece (the position and posture of the hand with respect to the workpiece) may depend on the type (shape) and posture of the workpiece. The simulation device 90 may include a gripping form registration unit 15 that registers a plurality of gripping forms depending on the type (shape) and posture of the workpiece and performs operation verification through simulation. The functions of the grip form registration unit 15 will be described with reference to FIGS. 13A-13C and 14A-14B. Here, as an example, a case will be described in which a parallel moving hand H1 is used as the hand, and a work W having a cylindrical portion 151 and a flange portion 152 formed at one end of the cylindrical portion 151 is used as the work.

Regarding the workpiece W, a gripping mode in which the cylindrical portion 151 shown in FIG. ), a gripping form (hereinafter referred to as gripping form 3) in which the other end 152b of the flange portion 152 is gripped is assumed as shown in FIG. 13C. The simulation device 90 (grasping form registration unit 15) accepts the designation of such gripping parts from the user, and also registers a plurality of gripping forms (grasping positions) of the hand model when gripping the plurality of different parts with the hand model. and posture). Specifically, the gripping form registration unit 15 receives a user's designation of a gripping part of the workpiece W, and automatically calculates a gripping position and orientation for gripping the specified gripping part of the workpiece W with the hand H1.

As an example, it is assumed that the grip portion specified by the user is one end portion 152a of the flange portion 152. In this case, the simulation device 90 (grasping form registration unit 15) determines the position and posture of the hand H1 in which the one end portion 152a is accommodated in the gripping space of the hand H1 and can correctly grip the one end portion 152a when the claw portion is closed. (grasping form 2). In this case, the simulation device 90 (gripping form registration unit 15) performs a simulation operation of the model of the hand H1 and the model of the workpiece W to confirm the operation. Using a similar method, the simulation device 90 determines the gripping position of the hand H1 on the workpiece W when the cylindrical portion 151 is designated as the gripping portion and when the other end 152b of the flange portion 152 is designated as the gripping portion. and calculate the posture (grasping forms 1 and 3).

The simulation device 90 (grip form registration unit 15) stores information on grip form 1-3. The above-mentioned registration is performed for each type (each shape) of the work expected to be used.

Next, the simulation device 90 (gripping form registration unit 15) randomly generates the posture of the workpiece W model, and selects the optimum grasping form for the generated posture from among the grasping forms 1 to 3 registered for the workpiece W. Choose from. For example, assume that the randomly generated posture of the workpiece W is as shown in FIG. 14A. In this case, among the postures of the workpiece W in the three gripping modes 1 to 3 shown in FIGS. 13A to 13C, it can be said that the posture of the workpiece W in the gripping mode 1 in FIG. 13A is closest to the posture in FIG. 14A. For example, in the posture of FIG. 14A, the angle θ of the center line C of the cylindrical portion 151 of the work W with respect to the vertical direction is about 20 degrees, and the vertical direction of the center line C of the cylindrical portion 151 in gripping forms 1 to 3 is approximately 20 degrees. Judging by the angle with respect to the gripper, it can be said that the posture in FIG. 14A is closest to the posture of the workpiece W in gripping mode 1 (FIG. 13A). In such a case, the simulation device 90 (grip form registration unit 15) can select grip form 1 as the grip form most suitable for gripping the workpiece W in the posture shown in FIG. 14A. Note that this criterion is just an example, and other criteria for selecting the most suitable grip form for randomly generated postures may be used.

Next, the simulation device 90 (gripping form registration unit 15) executes a simulation of gripping the work W in the selected gripping form 1. Specifically, the simulation device 90 moves the hand H1 model from a position away from the workpiece W and accessible to the cylindrical part 151 (for example, a position along the center line C of the cylindrical part 151). , move the hand 1 model to the grasping position (the position where the cylindrical part 151 is included in the grasping space of the hand H1), and move the claw part in the direction of closing the claw part until contact with the cylindrical part 151 is detected. .

The simulation device 90 generates a large number of random postures of the workpiece W, performs a gripping simulation as shown in FIG. 14B for each, and verifies that the workpiece W can be correctly gripped. By verifying that the workpiece W can be gripped correctly in all postures, the effectiveness of handling the workpiece with the hand on the actual machine can be verified in advance. For example, such a verification function can be effectively utilized to verify the operation of the hand according to the specifications generated by the hand specification determination unit 16.

By registering the gripping form registered here in the actual machine (i.e., robot control device), the vision sensor of the robot system can detect the posture of the workpiece, and the detected gripping form can be selected from among the registered gripping forms. This makes it possible to select a gripping form that is suitable for the selected posture, and to reflect this in the robot's picking operation of bulk workpieces.

As described above, according to this embodiment, it is possible to automatically teach an accurate grasping motion using a hand.

Although the present invention has been described above using typical embodiments, those skilled in the art will be able to make changes to each of the above-described embodiments and various other changes, omissions, and modifications without departing from the scope of the present invention. It will be appreciated that additions can be made.

In the above-described embodiment, the grasping condition input unit 11 was described as acquiring the parameters of the grasping conditions via the user interface, but the parameters of the grasping conditions are acquired from an external device to the simulation device 90 via a network, for example. It may be entered.

The program that executes the hand position/posture determination process etc. shown in the above-described embodiments can be executed on various computer-readable recording media (for example, ROM, EEPROM, semiconductor memory such as flash memory, magnetic recording medium, CD-ROM, DVD). - Can be recorded on optical discs such as ROM).

10 CPUs
11 Grasping condition input section 12 Hand position/posture determining section 13 Teaching point addition section 14 Grasping simulation execution section 15 Grasping form registration section 16 Hand specification determining section 20 Memory 30 Storage device 40 Display section 50 Operation section 60 Communication interface 90 Simulation device 500 Robot System 510 Robot control device 550 Vision sensor 600 Robot 650 Workpiece conveyance device

Claims (5)

a model data storage unit that stores a hand model and a workpiece model that are model data of the hand and the workpiece;
a gripping condition input unit that receives input regarding a gripping form of the workpiece model by the hand model, an approach direction of the hand model to the workpiece model, and a gripping portion where the hand model grips the workpiece model;
Using the hand model and the workpiece model, in a virtual space, from a first position where the hand model starts approaching the workpiece model, to a first position where the hand model can grip the gripping part of the workpiece model, a hand position/posture determining unit that determines the first position and the second position so that the hand model can move along the approach direction up to two positions without interfering with the workpiece model;
a teaching point adding unit that adds the first position and the second position to a robot operation program as teaching points;
a grasping simulation execution unit that causes a simulated grasping operation to close the fingers of the hand model at the second position, and stops the grasping operation when it is detected that the fingers come into contact with the workpiece model;
A robot simulation device equipped with When the finger portion of the hand model is configured as a soft hand,
The robot simulation device according to claim 1 , wherein the grasping simulation execution unit executes the grasping motion in a simulated manner using data representing the finger portion as a multi-joint model. The multi-jointed model includes a plurality of links and one or more joints connecting the plurality of links,
In the gripping operation, the gripping simulation execution unit includes:
(1) When it is detected that some of the plurality of links have contacted the work model, the movement of the contacted link is stopped;
(2) moving a link on the tip side of the stopped link until it contacts the work model;
Repeating this process until the tip of the plurality of links comes into contact with the workpiece model.
The robot simulation device according to claim 2 . a model data storage unit that stores a hand model and a workpiece model that are model data of the hand and the workpiece;
a gripping condition input unit that receives input regarding a gripping form of the workpiece model by the hand model, an approach direction of the hand model to the workpiece model, and a gripping portion where the hand model grips the workpiece model;
Using the hand model and the workpiece model, in a virtual space, from a first position where the hand model starts approaching the workpiece model, to a first position where the hand model can grip the gripping part of the workpiece model, a hand position/posture determining unit that determines the first position and the second position so that the hand model can move along the approach direction up to two positions without interfering with the workpiece model;
a teaching point adding unit that adds the first position and the second position to a robot operation program as teaching points;
a hand specification determining unit that determines specifications regarding a gripping force of a chuck used in the hand and a shape of the hand based on the weight of the workpiece and the arrangement relationship between the hand model and the workpiece model at the second position; ,
A robot simulation device equipped with Accepts designation of a plurality of different parts of the workpiece model as parts to be gripped by the hand model, and specifies a plurality of gripping positions and postures of the hand model when gripping the plurality of different parts with the hand model. further comprising a grip form registration unit for registering,
The gripping form registration unit randomly generates a posture of the workpiece model, selects one of the plurality of gripping positions and postures of the hand model based on the generated posture, and selects one of the plurality of gripping positions and postures of the hand model based on the generated posture. Verifying by performing a simulated gripping operation of the workpiece model at the gripping position and posture of the selected hand model;
A robot simulation device according to any one of claims 1 to 4 .

Images