JP6425718B2 - Assembly teaching device and method - Google Patents

Description

  The present invention relates to an assembly teaching device and method.

  When an assembly operation program is generated in advance in assembly automation utilizing a robot, direct teaching which is usually performed while operating the robot directly is common. In this direct teaching, it is necessary to teach all the series of operations desired by the robot for each operation, and the teaching operation becomes complicated, requiring a large number of man-hours, which is a heavy burden on the teaching operator.

Also, in recent years, with the diversification of customer needs, the production mode of products has shifted from small-lot mass-production type to multi-variety variable-volume production type, and it is desirable that assembly processes using robots correspond to many types. ing.
This causes the burden on the operator performing direct teaching to increase at an accelerated rate.

  Then, the automation technology which reduces the work burden of teaching conventionally is proposed. For example, in Patent Document 1, the image processing apparatus recognizes the identification sites and gripping positions of a plurality of tools, automatically selects and grasps the tools, and performs automatic replacement, thereby simplifying the automatic tool exchange apparatus, A technique for reducing the workload of teaching regarding selection is disclosed.

  Further, for example, Patent Document 2 discloses a technology for automating teaching of a gripping operation of a part by a robot hand.

Japanese Patent Application Laid-Open No. 62-264839 JP 2008-272886 A

  In the case of an assembly line utilizing a robot for which several types of general purpose hands are prepared, when trying to cope with the assembly of new parts, an appropriate hand is selected and selected from existing hands, and the gripping position of the part is further selected. It is necessary to decide. In this hand selection and gripping position determination, it is necessary to select the hand most suited to the characteristics of the part in consideration of the size, weight (mass) of the part, frictional force and the like.

  However, since the teaching operation for selecting the hand is particularly complicated in the entire teaching operation, and it is a heavy burden on the conventional worker, the need for automation of the teaching operation is high.

  Therefore, the prior art disclosed in Patent Document 1 selects one among a plurality of pre-given hands without considering the compatibility or compatibility with the parts to be gripped by the hand. is there.

  Further, the prior art disclosed in Patent Document 2 determines the gripping position of a part when a predetermined hand grips a predetermined part, and does not consider compatibility or compatibility with the part in selection. .

  Therefore, an object of the present invention is to provide an assembly teaching apparatus and method for automating teaching of an appropriate hand selection operation in consideration of compatibility with a component to be gripped, or optimizing the position of the component to be gripped. .

  The present invention is an assembly teaching apparatus for selecting a hand for gripping a part in assembly work of an assembly, comprising: a storage unit for storing a processing program (hand selection processing program) for selecting a hand and a related database; A data processing unit for executing a program, the related database includes a component information DB storing information on a component, and a hand information database storing information on one or more hands; By executing the selection processing program, teaching information for selecting a hand for holding a part is generated based on information of the part information DB and the hand information DB, and holding position information of the part is generated. It can be realized as an assembly teaching device characterized in that.

  Furthermore, the present invention can be realized as an assembly teaching method including the steps of performing the above-described processing.

  According to the present invention, by automating the selection of the hand and the generation of the holding position information of the part, it is possible to significantly reduce the number of teaching operations of the robot.

The block diagram of the assembly teaching device concerning one example of the present invention is shown. It is a figure showing hand tool information DB concerning one example. It is a figure showing parts information DB concerning one example. It is a figure showing the whole processing flow of the assembly teaching device concerning one example. It is a figure showing a part of processing flow of an assembly teaching device concerning one example. It is a figure which shows arrangement | positioning of the components of the assembly teaching apparatus concerning one Example. It is a figure which shows the 2 claw hand concerning one Example, and its imaginary hexahedron. FIG. 6 is a diagram showing a virtual hexahedron and a larger target part according to one embodiment. FIG. 2 is a view showing a virtual hexahedron and a wider target part according to one embodiment. It is a figure which shows the three claw hand concerning one Example, and its imaginary hexahedron. It is a figure which shows the movable range of the 2 nail | claw hand concerning one Example, and the width | variety of object components. An example of the input screen of the assembly teaching apparatus concerning one Example is shown. It is a figure which shows the outline of an example of the calculation method of the holding | grip position which the moment concerning one Example becomes the minimum. It is a figure and a graph showing suction of parts by a suction hand concerning one example. It is a figure and a graph in which an adsorption side concerning one example shows adsorption of parts by two adsorption hands. It is a figure which shows the example of holding | grip of the ring-like part by the hand of the outer side opening concerning one Example, and a graph. It is a figure which shows the hand which has a hand system of 2 system | strains concerning one Example. It is a figure which shows the processing flow of the components holding surface extraction concerning one Example.

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

  Embodiments of the present invention will be described according to the drawings. FIG. 1 is a block diagram of an assembly teaching device 100 according to the present embodiment.

  The assembly teaching device 100 includes a data processing unit (CPU 10) such as a computer that executes a program or processes data, an input unit 20 that receives an input signal including an instruction from a user, and a display unit 30 that displays at least an input screen. A storage unit 40 for storing a database of parts and hands and processing programs, a hand 3D-CAD apparatus 101 for generating design data of the hand, and a product 3D-CAD apparatus 102 for generating design data of the parts; It is comprised from vision systems 103, such as a camera which can take in product shape data, and a scanner.

  The storage unit 40 includes a part information DB 104 for storing information on the shape, size, material, surface condition, mass, etc. of parts obtained from the product 3D-CAD device 102 and the vision system 103, such as a hand, a driver, and a jig. A hand / tool information DB 117 for storing tool information and a hand selection program 50 which is a processing program for selecting an optimum hand are stored.

The hand selection program 50 includes an assembly order generation unit 105 that generates an assembly order and an assembly direction of a product consisting of a plurality of parts, a component holding surface extraction unit 106 that extracts a surface or position that can be gripped by a hand on the component, A part-hand information collating unit 107 that compares information with a hand or a tool, a part-hand compatibility evaluation unit 108 that evaluates the adaptability of a part and a hand, and a hand determining unit 109 that determines an optimal hand; A component holding position generating unit 110 for generating a holding position of the component when holding the target component with the determined hand, and a path generating unit 111 for generating a path for moving each component from the initial position to the assembling position; , Hand switching number counting unit 112 for measuring the number of hand switchings (number of replacements) until assembly of parts is completed, and assembly time for calculating assembly time of parts A calculation unit 113, stores.
Here, the hand 3D-CAD apparatus 101 and the product 3D-CAD apparatus 102 may be configured as one apparatus as an apparatus having both functions. Among them, as shown in FIG. 2A, the hand / tool information DB 117 contains, as an example of the contents of the hand / tool information, the type of hand, for example, the nail type, two nail type and three nail type as well. , Hold the part in the inner closed type, hold the part in the outer open type, etc., also handle the product by suction instead of the nail type, various types of shape information such as finger type, open / close operation range of the hand, Various information such as the payload is stored.

  In the assembly order generation unit 105 and the component gripping surface extraction unit 106, information obtained by exhaustively extracting the grippable surfaces of the components by the component gripping surface extraction unit 106, and the assembly sequence and assembly generated by the assembly sequence generation unit 105. Depending on the direction information, the side on which the part is placed during assembly or the side that needs to be shared with other parts during assembly is not held by the hand (cannot be held), so use two or more other parts for holding the part It has a function to determine the (details described later).

  In addition, the part-hand information collating unit 107 acquires part information such as the shape, size, and mass of the part obtained from the part information DB 104 (see FIG. 2B), the hand and the tool, in order to hold the part by the hand. Compare the information in

  The part-hand information collating unit 107 compares the size of the part with the movable range of the hand, the comparison of the mass of the part with the transportable mass of the hand, and the degree of slip between the hand and the part. Extract candidates. Thereafter, for each candidate of the hand, the part-hand suitability evaluation unit 108 calculates and evaluates the conformity between the part and the hand qualitatively or quantitatively using, for example, an evaluation function.

  The component-hand information collating unit 107 and the component-hand compatibility evaluation unit 108 are provided with a plurality of types of hands prepared in advance so as to correspond to an arbitrary component, for example, an adsorption type for adsorbing and gripping a component, A grip type in which parts are held and held by a plurality of plate-like or claw-like members, and an open-open type in which hollow-type parts are openly held by a plurality of plate-like or claw-like members Evaluate compatibility qualitatively or quantitatively. Here, the details of the method for evaluating the combination of the part and the hand according to the present embodiment will be described later.

  Among the hands and tools evaluated by the parts-hand compatibility evaluation unit 108, the hands and tools evaluated by the parts-hand compatibility evaluation unit 108 by the hand determination unit 109, which is the next process, For example, the hand or tool with the largest evaluation value is determined. Here, whether the evaluation value should be determined using the hand or tool with the largest value or the hand or tool with the smallest value is determined by the setting of the evaluation function (described later) that is the basis of the calculation. The decision is different.

  When the hand / tool is determined by the hand determination unit 109, next, the component grip position generation unit 110 determines which region of the component should be gripped by the hand or tool (details will be described later). Subsequently, the path generation unit 111 generates a path for moving each component from the initial position to the assembly position where the parts are assembled. After that, the hand switching count (number of replacements) until assembly of the parts is completed is measured by the hand switching count unit 112, and then the assembly time calculation unit 113 calculates the assembly time of the parts.

  Subsequently, an operation flow of the assembly teaching device according to the present embodiment is shown in FIG. Here, the hand considered in this embodiment is, for example, a hand having two claws and three claws, a type in which parts are gripped by inner closing, a type in which parts are gripped by outer opening, or a suction type, or A finger type (not shown) imitating a human hand, and a hand configured by a combination thereof can be considered.

  When the start of the assembly teaching device is started (START S2000) and based on the product information of the product 3D-CAD device 102, the assembly sequence generation unit 105 generates an assembly procedure and a direction for assembly of parts (S2001) .

  Next, the number of parts is set to N and the number of hands is set to n (S2002). Next, in this operation flow, the values of the counter K for counting the number of parts and the counter Q for counting the number of hands are initialized (the value is set to 0) (S2003).

  Subsequently, the counter K is incremented by 1 (S2004), and based on the information of the part-hand information collating part 107 in the hand selection program 50 in the storage part 40 for the first part of the assembly, that is, the first part. The narrowing-down of the hand candidates that can be gripped and the allocation corresponding to the parts are performed on the first part (S2005). Subsequently, the number of component gripping surfaces is confirmed (S2006), and when the existence of two or more surfaces can be confirmed, the process proceeds to the next step, and the counter Q of the number of hands is incremented by 1 (S2008). Next, the process proceeds to the step of selecting each hand type, for example, each type of hand of the nail type, suction type and finger type (S2009). Here, since the suction type hand can be suctioned if there is at least one suction surface, it is possible to cope with the condition of two or more surfaces (S2009).

  The component gripping surface extraction unit 106 extracts the component gripping surface of the first component (S2010), and generates a virtual hexahedron (hereinafter, a virtual space of a hexahedron) serving as an index of the size that can be gripped by the hand (S2011) ). The details of this virtual hexahedron will be described later.

  Subsequently, the virtual hexahedron space formed by the two- or three-nail type hand is compared with the size of the part to be gripped to evaluate whether the first part can be gripped by the first hand ( S2012). Next, when gripping the part with the hand, the gripping position is calculated so as to minimize the moment in the operation after gripping (within the surface that can be gripped) (S2013).

  Here, an outline of an example of a method of calculating the grip position at which the moment is minimized will be described with reference to FIG.

Here, for the sake of explanation, the movement direction of the hand is the + Z direction (220Z) in the drawing.
In FIG. 12A, the component 223, the protrusion 223a on the component 223, the gravity center position 223g of the component, the hand 220, and the two claws 222 of the hand, the component gripping center 220c, the component gravity center position 223g and the component gripping center The distance to 220c is L, the mass of the component is m, the gravitational acceleration is G, and the moment 225 generated around the gripping center 220c is the product mass of component mass m × gravitational acceleration G times distance L times m × G × It becomes L. Here, when it is possible for the grip center 220c to approach the gravity center 223g of the part, it is desirable to bring the hand closer to the position as close as possible to the gravity center position to reduce the moment m × G × L.

  Here, (b) of FIG. 12 is a diagram in which the hand 220 is closest to the gravity center position 223g of the part in (a) of FIG. 12, but since the part 223 has a protrusion 223a, L = 0 The hand 220 can not be brought close to the component center of gravity 223 g to the position. In FIG. 12C, the horizontal axis represents the distance L from the component gravity center (223 g) to the hand gripping center 220c, and the vertical axis represents the moment applied to the hand gripping center 220c.

  The state of L = L2 is shown in FIG. 12 (a), and the state of L = L1 is shown in FIG. 12 (b). From the above, it is desirable to approach L = 0 if it is desired to reduce the morton to be added to the center of the grip position, but if it is difficult due to the structure and shape of the grip parts, the hand, In the example of c), L = L1 and the moment MO = MOmin. The position where the L is minimized is calculated by the component gripping position generation unit 110 based on the data of the product 3D-CAD device 102. Next, the assembly teaching flow will be further described using FIG. Hand candidates are extracted from the plurality of hands, and a gripping position at which the part grips the part is calculated (S2014).

  Next, in the combination of the first part and the hand that holds it, the path generation unit 111 generates a path from part gripping to part assembly, and there is a part, a hand or a robot arm (not shown) in the path. It is checked whether there is no interference with the robot ambient environment, for example, an obstacle such as a part supply platform or a cage that constitutes an assembly platform (S2016). Here, if there is no interference, the number of assembly times of parts and / or the number of switching (replacement) of hands are counted as the next step (S2017). Here, since it is necessary to perform the same processing for one part with a plurality of hands and to calculate the compatibility evaluation between the part and the hand, the loop of A and the number n of times of hands is repeated.

  Further, since the same repetition is necessary for the number N of parts, the process is repeated from S2004. When a series of N × n loops is completed, next, a hand combination that minimizes the component accumulation assembly time T is extracted (S2020), and an actual robot operation program is automatically generated (S2021).

Here, the hand combination in which the part accumulated assembly time T is minimum can be considered as a low cost assembly operation.
By executing these processing flows, it becomes possible to determine the hand replacement schedule such as the type of hand to be replaced, the number of times of hand replacement, the timing of hand replacement, etc., corresponding to the parts to be assembled.

  Subsequently, when the operation program generated in S2021 is executed (S2022), a hand corresponding to the parts necessary for assembly is attached (S2023), a series of assembly operations of products not shown are executed (S2024), and the operation ends (S2025).

  Subsequently, in FIG. 3, a method of evaluating the combination of the hand and the part described in S2012 will be described.

  First, the magnitude relationship between the hand and the part is evaluated (S2012a). Next, the mass of the part and the load resistance of the hand (hereinafter referred to as mass resistance) are evaluated (S2012b). Evaluation is carried out (S2012c), and the degree of fitness of the hand for any part is calculated.

  The hand adaptability to this optional part will be described in more detail with reference to FIG. Here, FIGS. 13 to 14 show an outline of a suction type hand.

  The suction hand 230 having one suction surface shown in (a) of FIG. 13 is composed of a base 231 of the hand, a suction hollow shaft 232 and a suction disk 233. Reference numeral 230c denotes a substantially center line of the suction hand 230, 234 denotes a component to be assembled, 234g denotes a component center of gravity, and 234c denotes a center of gravity line passing through the component center of gravity. Further, the suction hand 230 shown in (a) of FIG. 13 moves in the -Z direction at the lower side of the drawing, and tries to suction the component 234. Here, the mass of the part 234 is m.

Further, FIG. 13B is a view showing that the component 234 is sucked by the suction hand 230 and is moving in the + Z direction above the drawing. FIG. 13C shows the barycentric position 234g of the part 234 in FIG. 13A, and the size (width in the same figure) of the part. The part is a substantially rectangular parallelepiped, the width of the part is 2L, and the distance from the center of gravity to one end is L. Further, (d) in FIG. 13 in FIG. 13 (c) shows a state in which substantially the center line 230c of gravity line 234c and suction hand parts are shifted by _{L 3.}

  Moreover, the relationship of the moment M which generate | occur | produces at the time of adsorb | sucking and lifting components by a adsorption | suction hand at (f) of FIG. The horizontal axis is the distance L from the component center of gravity to the suction hand grip (suction) center, the vertical axis is the moment MO applied to the suction portion, and the straight line 240 is a straight line of the moment MO showing a mass m × gravitational acceleration G × distance L There is. Assuming that the mass m of the part does not change during adsorption, it goes without saying that in order to make the moment MO a small value, the distance L to the center of gravity of the part must be reduced. In the example shown in FIG. 13, since the component suction surface 234T is in a substantially flat state, suction with the suction hand is possible in the region within the component suction surface 234T.

  Here, (e) of FIG. 13 will be described with reference to an example in the case where the part shapes are different. The part other than the part related to the part 235 in (e) of FIG. 13 is common in FIG. The part 235 shows an example in which the surface forming the part is not a uniform surface, and the suction surface 235T has a partial convex. When the component 235 is to be suctioned by the suction hand 230, the component gripping position generation unit 110 may preferentially calculate the surface other than the suction surface 235T as a priority suction surface. In (e), the case where the suction surface 235T is used as a suction surface will be described for the purpose of explanation.

  As described in FIG. 13E and so far, the smaller the distance from the center of gravity of the part to the hand holding position, the smaller the influence of the moment and the smaller the load applied to the hand. However, as shown in FIG. 13E, if there is a protrusion 235U which can not be adsorbed by the suction hand in the vicinity of immediately above the gravity center line 235c of the part, it is necessary to avoid the location with a minimum distance. As an example of this avoidance method, it avoids by the method demonstrated by (b) of FIG. Further, the avoidance process is calculated by the component gripping surface extraction unit 106. Subsequently, the case of suctioning a part with another form of hand will be described.

  An adsorption hand 240 having two adsorption surfaces shown in (a) and (b) of FIG. 14 includes a base 241 of the hand, suction hollow shafts 242l and 242r, and suction cups 243l and 243r. Reference numerals 240a and 240b denote center lines of the suction hollow shafts 242l and 242r. 244 is a component to be assembled, and 244g indicates the position of the center of gravity. Further, similarly to (a) of FIG. 13, the suction hand 240 shown in (a) of FIG. 14 moves in the −Z direction at the lower side of the drawing to suction the suction surface 244T of the component 244. Further, FIG. 14B is a view in which the component 244 is adsorbed by the suction hand 240 by the suction surface 244T and is moving in the + Z direction above the drawing.

  (C) of FIG. 14 shows a moment diagram. It can be understood from this figure that when the center of gravity position 234g exists between the suction cups (between -i and + i), generation of a moment is smaller than otherwise. This indicates that the load on the hand 240 is also small. In the drawing, these calculations are also performed by the component holding position generation unit 110, and it is possible to reduce the load on the upper-level device to which the hand or the hand not shown is attached. As shown in FIG. 13 and FIG. 14, since the suction type hand basically requires only one surface for component suction, handling of components with complicated shapes and parts where the flat area is small and limited It is effective for

  Subsequently, FIG. 4A shows an example of a flow applied to a suction type hand, and FIG. 4B shows an example of a flow applied to a finger type hand not shown. In the case of the suction type hand shown in (a) of FIG. 4, if two or more gripping surfaces of the component with the hand can not be taken at S2006 in FIG. )) S3001). Here, when the suction surface can not be found, the process flow moves to D in (b) of FIG. 4 which is a flow in the case of using a finger type hand described later.

  If a suction surface is found in S3001, the degree of matching between the hand and the part is calculated (S3002). Subsequently, when the hand picks up a part and the hand tries to move to the next posture, the hand suction position is calculated so that the moment acting on the hand is minimized by the mass of the part (S3003). The suction position is determined (S3004), and the operation temporarily moves to S2015 shown in FIG. The method of minimizing the moment in a grippable state has been described in FIGS. 12 and 13 and thus will not be described here. Here, the comparison between the suction type hand and the part in S3002 will be described next.

  S3002a is a step of evaluating the mass of the part and the mass resistance of the hand, and when the mass of the part obtained from attribute information of 3D-CAD information is likely to exceed the mass resistance of the hand, the combination of the part and the hand is inappropriate Then, the process moves to A shown in FIG. 3 and the hand is reviewed again. On the other hand, if the mass tolerance is not exceeded in step S005, the degree of slippage between the part and the hand is evaluated in the next S3002b.

Here, the information on which the evaluation of the slippage is based is, for example, from attribute information that the 3D-CAD devices 101 and 102 have. Next, a flow in the case of selecting a finger type hand (not shown) is shown using (b) of FIG.
Here, the finger-type hand is a hand provided with one or more sets of articulated finger-shaped connecting members.

  When the suction surface can not be detected in S3001 of (a) of FIG. 4, the process transitions to the flow using the finger type hand of (b) of FIG. 4. First, in S3007, each step (S3007a and S3007b) of the combination evaluation of the finger type hand and the part to be gripped is performed. The details of this evaluation will be described later. After this assembly evaluation, the moment applied to the hand when gripping the part is calculated (S3008). For example, when the gripping position is changed at several places arbitrarily, the moment amount changes, but the moment amount is calculated at least at the plurality of grippable positions, and the gripping position is determined so as to be the minimum (S3009).

If the part mass is heavier than the weight resistance of the hand, the processing is moved to A (S2007) shown in FIG. 3 as over load, and the flow for selecting the next hand candidate is entered.
If the part mass is equal to or less than the weight resistance of the hand, evaluation is performed in the step of evaluating the sliding degree of the part and the hand (S3007b).

  Subsequently, extraction of the hand gripping position taking into consideration the assembly procedure of the product, which is a feature of the present embodiment, will be described with reference to FIG. FIG. 5A shows a work table 180 for assembly, a part A181 that constitutes one part of a product, and a part B182 as well, and parts A and B have not been assembled yet. A state of being placed on the work table 180 in the level state is shown.

  Here, the surface 181a constituting one surface of the component 181 is a surface which contacts the component B when assembling in the future, and the surface 182b is a surface facing the surface 182a, for example, by a two-claw type hand For example, the surface 182a and the surface 182b can be used to grip the part 182. Further, the hatched surface 182a of the part B 182 shows the surface in contact with the part A 181 when the assembly is performed in the future. (B) of FIG. 5 is a view during assembly of the part 181 and the part 182, and (c) of FIG. 5 shows a final form in which the part A181 and the part B182 are assembled. Here, 181a and 182a, which become contact surfaces of two parts after assembly, are connected to the assembly order generation unit 105 based on the part information DB 104 obtained by the product 3D CAD apparatus 102 or the vision system 103 of FIG. Are extracted.

  Here, the hand used is the same for part extraction and part assembly. Also, consider the case where parts are not exchanged during operation transition from part extraction to part assembly.

  In the part B 182 of FIG. 5A, it is the surface 182c in contact with the work table 180. For example, the surfaces 182a and 182b can be gripped using a hand except for the surface 182c. However, when the state after completion of assembly shown in (c) of FIG. 5 is predicted, the surface 182a of the part B and the surface 181a of the part A are in contact with each other. It can not be. Therefore, in the use hand determined by the hand determination unit 109 and the grip position determined by the component grip position generation unit 110, the assembly order generation unit 105 calculates in advance the state after the end of assembly, In this case, the grip surface is determined by excluding the contact surface after assembly in advance. This process is a major feature of the present embodiment, and FIG. 17 shows a diagram expressing these in the processing flow.

  Further, in the flow shown in FIG. 17, processing is performed in the component gripping surface extraction step (S2010 in FIG. 3) by the component gripping surface extraction unit 106 (detailed explanation is omitted). Next, an example of a method of determining whether an arbitrary part can be gripped by an arbitrary hand will be described using FIGS. 6 and 7. The contents to be described here are processed in the component-hand information collating unit 107 in FIG. 1 and FIG. 3 and S2012a in the step of evaluating the magnitude relationship between the hand and the component.

  FIG. 6 is a view schematically showing a two-nail hand. FIG. 6A is a schematic perspective view of a two-nail hand, and the hand 190 is composed of a base portion 191 of the hand and two claws 192, and the two claws open and close inward and outward in the X direction. The parts can be gripped by doing this. (In this description, the description of the drive unit such as the actuator for driving the claws of the hand is omitted.) FIG. 6 (b) is a view when the distance between the claws of the two claw hand is maximized to Bmax. It shows a state in which a hexahedron virtual space 193 is formed in a region surrounded by the base portion 191 and the two claws 192.

FIG. 6C is a front view of the two-nail hand, in which the distance between the claws is Bmax, and the distance between the claws is minimally small (broken line 192a). The dimension is Bmin. (D) of FIG. 6 is a diagram extracting the virtual space 193 of the hexahedron.
FIG. 7 shows a hexahedron virtual space 193 and a component 194 to be gripped by this two-nail hand.

  FIG. 7A is a view showing the dimensional relationship between the virtual space 193 of hexahedron and the part 194, and the dimension Bp in the width direction of the part with respect to the dimension Bmax in the opening / closing direction of the hand satisfies the condition Bmax> Bp. It is a figure in the case of satisfy | filling. FIG. 7B is a diagram in which the hexahedral virtual space 193 and the part 194 are overlapped and expressed, and since Bmax> Bp, the virtual face of the hexahedron formed of the base portion of the hand and the two claws The state in which the part 194 is contained in the space 193, that is, it is shown that the part 194 can be gripped by the two-nail hand 190.

  In FIG. 7C, the state of the hexahedral virtual space 193 is the same as in FIGS. 7A and 7B, but the dimensional relationship of the component 195 to be gripped is different from that of the component 194. The case is shown. In FIG. 7C, Bmax <Bp. Similarly to (b) of FIG. 7, (d) of FIG. 7 is a diagram in which a virtual space 193 of hexahedron and a part 195 are overlapped and expressed. Here, as shown in (d) of FIG. 7, since Bmax <Bp, the component 195 is in a state of being extended beyond the virtual space 193 of the hexahedron. That is, it indicates that the component 195 can not be gripped by the two-nail hand 190.

  As described above, the part-hand information collating unit 107 performs a process of overlapping the virtual space of the hexahedron that can be formed between the claws and the claws of the hand and the part to be gripped, thereby providing a two-nail type hand to the part. It can be determined whether or not it can be gripped. Next, another gripping example will be described using FIG.

  FIG. 8A shows a hexahedron virtual space 193 and a part 194 formed by the two-nail hand shown in FIGS. 6 and 7. Similarly to the above, reference numeral 193a denotes a surface sandwiched by two claws.

  In the state of FIG. 8A, since Bmax <Bp, the component 194 can not be gripped by the two-claw hand 190 unless the relationship between the two-claw hand and the direction of the component changes. (B) of FIG. 8 shows a state in which the direction of the two-nail hand 190 is rotated by 90 degrees with respect to the part in (a) of FIG. In this state, the width for the part of the virtual space 193 of the hexahedron is Bmax, and the width of the part is Wp, and Bmax> Wp as shown in FIG. 8B, as shown in FIG. When the two are superimposed on each other, the part 194 is included in the virtual space 193 of the hexahedron.

  That is, when the surface direction held by the hand with respect to the part is fixed, if the part is larger than the width of the virtual space of the hexahedron, it is impossible to hold the hand, but the hand is intentionally rotated about 90 degrees By doing this, it may be possible to grip the part, so in FIG. 1, the part-hand information collating unit 107 collates assuming that the hand is rotated with respect to the part.

  Then, FIG. 9 is a figure at the time of changing a hand form from the hand of 2 claws till now to 3 claws hand. 9 (a) is a schematic perspective view of the three-nail hand 200, FIG. 9 (b) is a view of a virtual space of a hexahedron assumed inside the nail as an example in FIG. 9 (a), FIG. (C) is the figure which looked at the 3 nail | claw hand 200 from the top. The three-nail hand 200 is composed of a base portion 201 of the hand and three claws 202, and these three claws can grip parts by opening and closing inward and outward in the direction of arrow E in the figure. .

FIG. 6 is a view showing a state in which the 3-claw 202 is in a state in which the distance between the claws is expanded to the maximum, and the 3-claw indicated by the broken line 202 b is gripping the component 204.
The relationship between the hexahedron virtual space and the parts to be gripped is basically the same as the contents described with reference to FIGS.

  Next, with reference to FIG. 10, an evaluation method regarding the gripping operation of the hand and the part will be described using an example. The contents described here are the part-hand compatibility evaluation unit 108 in FIG. 1 and FIG. 3 for evaluating the magnitude relation between the hand and the part, step S2012a for the parts and parts, and the mass resistance evaluation step S2012b for parts and the parts and hands The process is performed in step S2012 c of the sliding degree evaluation step of

FIG. 10 is a view showing a two-nail type hand and components to be gripped for the sake of simplicity.
Here, the two-nail hand 210 is composed of the base portion 211 of the two-nail hand, the support shaft 211a of the hand, and the two claws 212, and the state of the two claws is indicated by 212a when the distance between the two claws is maximum. Similarly, the state of the nail when it is minimized is indicated by 212b.

The interval when the distance between the two claws is maximum is indicated by L1, and the interval when the distance between the claws is also minimum is indicated by L2. Further, the width dimension of the part to be gripped here is denoted by Lp. Here, in a desirable ideal state as a hand, the ratio of Lp to L1 is sufficiently small when the claw is open ((Lp / L1) << 1), and the ratio of Lp to L2 when the claw is closed Is sufficiently large ((Lp / L2) >> 1), and if these conditions are satisfied, the opening and closing margin of the nail with respect to the size of the part becomes high. Therefore, the equation (1) is defined as an index of the opening and closing margin of the nail as an example.
Lmargin (%) = [{1- (Lp / L1)} × 100 + {1-1 / (Lp / L2)} × 100]
= [{1- (Lp / L1)} + {1- (Lp / L2)}] x 100 ---- (1)
Here, when evaluating from the viewpoint of the mass of the part and the mass resistance of the hand, assuming that the mass of the part is Mp and the mass resistance of the hand is Mlimit, the smaller the mass of the part is, the higher the margin is with respect to the mass resistance of the hand. Become. Here, when the margin Mmargin with respect to mass is defined as an example, it becomes the formula shown in (2).

Mmargin (%) = {1- (Mp / Mlimit)} × 100 ---- (2)
Further, the evaluation of the degree of slippage between the part and the hand depends on the coefficient of friction μ between the part and the hand, and the force F with which the hand grips the part. When the mass of the part is Mp, the friction coefficient is μ, the gravitational acceleration is G, and the force with which the hand grips the part lifts the part vertically, the balance is balanced under the condition shown by equation (3) It will be in the state.

μ × F = Mp × G ---- (3)
In addition, it is possible to lift the part by the hand under the condition expressed by the equation (4).

μ × F> Mp × G
μ> (Mp × G) / F (where μ ≦ 1)-------(4)
Furthermore, assuming that the moment applied to the hand is MOp and the moment allowable to the hand is MOlimit as an index of the margin of moment applied to the hand, the margin is smaller when the moment MOp applied to the hand is smaller than the allowable moment of the hand. Get higher. Here, when the margin MOmargin for the moment is defined as an example, MOmargin (%) = {1- (MOp / Mlimit)} × 100 ---- (5)
It can be defined as

  As described above, the evaluation index (evaluation function f) of the part and the hand in consideration of the size, mass, moment applied to the hand, and friction state is summarized as shown in the equation (6) as an example. Here, the coefficients a, b, c and d respectively indicate the weight, the mass, the moment, and the weighting coefficient relating to the friction state, and needless to say, in the case of a = b = c = d = 1, the size, mass, and moment , Indicates that the weight of the friction state, that is, the importance is equal.

f = a × Lmargin + b × Mmargin + c × MOmargin + d × μ ---- (6)
a, b, c, d: weighting factor
Further, the evaluation index may extend the equation (6) and take the form of the mean square of the size, mass, moment, and friction state as shown in the equation (7).

f = {a × Lmargin ² + b × Mmargin ² + c × MOmargin ² + d × μ ² } ^1/2 ---- (7)
a, b, c, d: weighting factors Next, FIG. 11 shows an example of the input screen of the assembly teaching device in the present embodiment. This screen is displayed on the display unit 30 in FIG. 1, and the input operation is performed by the input unit 20 including a keyboard, a mouse and the like. 11, an input unit 501 for inputting a product name (file name) of data of the product 3D-CAD apparatus 102, a display unit 502a for displaying 3D-CAD information of product completion stored in the apparatus 102, and confirmation What shows the appearance of the part arrangement layout for the purpose is shown in 502b.

Also, here, the hand gripping position surface designation menu 503 is selected so that the component gripping position on the hand can be input or designated, and the cursor 506a or 506b for gripping position surface designation of the hand is displayed in the display unit 504. Make a specification. In FIG. 11, it is shown that the hatched 507a and the opposite surface 508a of the claw on the opposite side are designated as the component holding position surface of the hand. Here, the component holding position surface of the hand may be data stored in the 3D-CAD device for the hand, and for example, the hand holding surface of the claw may be set in advance by attribute setting or the like.
Reference numeral 509 denotes a confirmation screen of evaluation functions of hands and parts, 510 denotes an assembly order generation button, and 511 denotes an execution start button of the assembly teaching process shown in FIG.

In addition, after data acquisition of CAD drawing information and designation of the hand gripping position are completed, a series of assembly teaching is automatically performed by pressing the teaching execution button.
Here, the example of the structure in which the hand has only one set of gripping portions has been described above, but the scope of application of the present embodiment is not limited to this. For example, as shown in FIG. It may be a holding function, or a structure having two or more sets of suction functions, or a holding function and a suction function.

Here, an example in which the form of the hand is different will be described with reference to FIG.
The hand 250 shown in FIG. 15 is composed of a hand base 251 and three claws 252. 250c indicates the center line of the hand 250. Reference numeral 253 denotes a ring-shaped component, and the three claws 252 have a structure suitable for gripping the component 253 at the center hole 235a.
As shown in FIG. 15, the three claws 252 are close to each other when passing through the part 253, and after passing through the part 253, the claws spread in the J direction in the figure and grip the part 253 can do.

This hand differs from the hand described so far in that it is configured to grip parts with an outer opening.
FIG. 15F shows the relationship between the movable range of the claw of the hand and the inner circumferential diameter of the ring-shaped part. Here, assuming that the movable range of the claw is R1 to R2 and the inner circumferential diameter of the ring-like part is rp1 to rp2, gripping is possible under the condition of R1 <rp1 <rp2 <R2. The calculation of the graspable range is also performed by the part-hand information collating unit 107 part. The method of selecting the hand, the method of determining the gripping position, and the concept of the opening margin of the part and the hand are the same as the methods described above, so the detailed description is omitted here.

FIG. 16 shows an example in which two hand functions are integrated into one hand as an example.
FIG. 16 shows a schematic perspective view of a hand 260 having a structure in which two hands of two claw type are formed by one hand.

  The hand 260 includes a base portion 261 of the hand and two sets of claws 262 (first claws) and 263 (second claws), and the two pairs of claws are independent inward and outward in the X direction. It is designed to open and close. Further, in the figure, hatched 262a and 263a indicate gripping surfaces for the parts of the claws 262 and 263, respectively. The present embodiment can also be applied to a hand having a plurality of claws and suction cups for these one hand.

  As described above, according to the present embodiment, even when assembling a product using a new part, a hand (including a tool) suitable for handling the part is automatically selected, and the gripping position of the part is also selected. Automatically generate. In addition, since the hand selection information and the gripping position information are reflected in the operation program of the robot, it is possible to improve the efficiency of the teaching operation and save labor.

10 ... CPU (data processing unit)
20: input unit, 30: display unit, 40: storage unit,
50 ... hand selection program, 100 ... assembly teaching device,
104 ... part information DB, 105 ... assembly order generation unit,
106: part gripping surface extraction unit 107: part-hand information collating unit
108 ... parts-hand suitability evaluation unit, 109 ... hand determination unit,
110: Component gripping position generation unit 111: Path generation unit
112: Hand switching number counting unit 113: assembly time calculation unit 117: hand / tool information DB.

Claims (4)

An assembly teaching apparatus for selecting a hand for holding a part in an assembly operation of an assembly, comprising:
A storage unit for storing a processing program for selecting a hand and a related database;
A data processing unit that executes the processing program;
Equipped with
The related database is
A part information DB storing information on parts;
A hand information DB storing information on a plurality of hands,
Including
The data processing unit executes the processing program to
Generating a procedure and assembly direction for assembling the assembly,
The candidate of the hand suitable for the part is extracted based on the information of the part information DB and the hand information DB, the compatibility of the part and the hand is evaluated, and the part is gripped from among a plurality of hands. Generate teaching information to select a hand,
Based on the information on the procedure and direction of assembly of the assembly, and the information on the part information DB and the hand information DB , excluding the side on which the part is placed during assembly and the side that needs to be shared with other parts in assembly and to generate teaching information for determining the holding position of the component,
In addition, calculate the total assembly time of the parts,
Based on the information on the total of the calculated assembly time, calculate the type of hand to be exchanged, the number of times of exchange of the hand, the exchange schedule of the exchange timing of the hand so as to minimize the total assembly time. An assembly teaching device characterized by the above. The part information DB includes information indicating the size, mass, center of gravity position, material, and surface condition of the part,
The assembly teaching device according to claim 1, wherein the hand information DB includes information indicating a type of hand, an open / close operation range, and a portable mass. The data processing unit refers to the information of the component information DB and the hand information DB in the generation of the teaching information.
The teaching information for selecting the hand is generated on the basis of compatibility with at least one or more physical attributes of the hand and the part, size, mass, center of gravity position, material, and surface condition of the hand. The assembly teaching device according to 1 or 2. An assembly teaching method for selecting a hand for gripping a part in an assembly operation using a computer, comprising:
The computer executes a processing program for selecting a hand in the data processing unit,
An assembly sequence generation process for generating an assembly assembly procedure and an assembly direction;
Based on the DB related to the part information stored in the storage unit and the DB related to the hand information, the candidate of the hand suitable for the part is extracted, the compatibility of the part and the hand is evaluated, and the part is selected from a plurality of hands. A hand selection information generation step of generating teaching information for selecting a hand to be held;
Based on the information on the procedure and assembly direction for assembling the assembly generated in the assembly order generation processing step, and the information on the component information DB and the hand information DB, the surface on which the component is placed at the time of assembly and the other A gripping position information generation step of generating teaching information for determining the gripping position of the part excluding the surface that needs to be shared with the part ;
A cumulative assembly time calculating step of calculating a total of assembly time of the parts;
Based on the information on the total of the calculated assembly time, a hand for calculating the type of hand to be exchanged, the number of times of exchange of the hand, and the exchange schedule of the exchange timing of the hand so as to minimize the total assembly time. An assembly teaching method comprising: executing an exchange schedule calculating step.

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