GB2098578A

GB2098578A - An industrial production system served by a plurality of operating arms and controlled by a computer system

Info

Publication number: GB2098578A
Application number: GB8137408A
Authority: GB
Original assignee: DEA Digital Electronic Automation SpA
Current assignee: DEA Digital Electronic Automation SpA
Priority date: 1981-05-15
Filing date: 1981-12-11
Publication date: 1982-11-24
Also published as: GB2098578B; JPS57194843A; IT1144708B; IT8167648A0; FR2505718A1; DE3217967A1

Abstract

An industrial production system including a plurality of operating arms (2) and controlled by a computer system (1) is described. Each of the arms (2) comprises a support structure for a gripping end (3), this structure comprising a single body (4) for supporting and guiding a single column (5). This body (4) is movable with respect to a support element (6) of the arm, such support element being fixable on a fixed body (7). The structure further includes means (13, 15; 22, 24; 25, 27) for rectilinear displacement of the end (3) with respect to the support element (6) along the directions (x, y, z) of a set of three orthogonal cartesian axes. <IMAGE>

Description

SPECIFICATION An industrial production system served by a plurality of operating arms and controlled by a computer system The present invention relates to an industrial production system (working and/or assembly) served by a plurality of operating arms (robots) and controlled by a computer system, in particular by a distributed hierarchical intelligence mini and microprocessor system.

As is known, current industrial production systems seek to obtain the maximum possible automation with an integration of different functions (true working, transport of the workpieces and of the tools, dimensional monitoring etc.), under the control of a processor system, frequently of distributed type. Existing automatic assembly systems are generally of a rigid type, that is they are able to perform the necessary operations only on classes of objects which differ only slightly from one another. The majority of the arrangements are the result of specific designs; this naturally involves a high level of investment so that the application of such systems has been restricted until now to situations involving relatively long production runs.

The object of the present invention is that of providing an industrial production system served by a plurality of operating arms, which overcomes the above indicated disadvantages, and which has distinct characteristics of flexibility, modularity and adaptability such that it can easily and rapidly be adapted to different productions, with different combinations of operating units and for different production volumes.

According to the present invention there is provided an industrial production system characterised by the fact that it includes a plurality of operating arms controlled by a computer system, each of the said arms including a support structure for a gripping end, the said structure comprising a single support and guide body for a single column, the said body being movable with respect to a support element for the said arm, the said support element being fixable on a fixed body, the said structure including rectilinear displacement means for the said end with respect to the said support element along the directions of a set of three orthogonal cartesian axes.

For a better understanding of the present invention one embodiment thereof will now be described, by way of non limitative example, with reference to the attached drawings, in which: Figure 1 is a perspective view of a combination of two operating arms controlled by a computer system to form an industrial production system according to the present invention; Figure 2 is a block schematic diagram of the computer system for controlling the arms of Figure 1; Figure 3 is a diagrammatic representation of different configurations of industrial production systems according to the present invention; Figure 4 is a schematic view of an assembly line formed according to the system of the present invention; and Figure 5 is an exploded perspective view of a product assembled on the line of Figure 4.

In Figure 1 there is shown by way of example an overall mechanical arrangement of the system.

A work bench 7 for supporting the tools and the workpieces which are to be worked, has fixed to one side thereof a common element 6 for the sliding support of two operating arm structures 2.

Each arm 2 carries a gripper end or head 3 having two relatively movable jaws 100. The structure of each arm 2 comprises a single support carriage 4 for a single vertical column 5, and carriage 4 is slidable along the axis of the support element 6.

The single column 5 is slidable along its own axis and carries at the top a carriage 8 which serves as a support and guide for a single horizontal beam 9 which carries the end head 3. This head 3, by means of carriages 4 and 8, can be displaced along three directions (x, y, z) of a set of three orthogonal cartesian axes respectively parallel to the axis of the support element 6, to the axis of the horizontal column 9, and to the axis of the vertical column 5. Between the column 9 and the head 3 on the structure 2 there can be mounted three further rotating motorised units (not illustrated) for turning the head 3 around three rotations indicated R1, R2 and R3, respectively around the axes y, x and z, only two of which can conveniently be provided simultaneously, to bring the arm up to the maximum normally envisaged configuration of five axes (three linear and two rotary).

The support element 6 is in the form of a vertically mounted I-section beam and is fixed to a plate 10 connected to the work bench 7 by means of a spacer block 11.

On one side of the element 6 there is fixed a rack 3 with which meshes a pinion driven by the output of a motor unit 1 5 fixed to the carriage 4 for driving the carriage 4 itself along the element 6. The motor unit 1 5 includes a d.c. motor with an incorporated tacho generator. The shaft of the motor is connected to the pinion via a reduction gearbox 1 8 of the worm screw-worm wheel type.

Detection of the position of the carriage 4 along the element 6 is effected by means of a known optical "encoder" of incremental type with reference notches which is keyed directly onto the motor by using the shaft passing therethrough both for drive and centring. The carriage 4 also constitutes a guide for the vertical column 5 along one side of which there is fixed a rack 22 with which meshes a pinion of a motor unit 24 similar to the motor unit 15 and fixed to the carriage 4.

Along one side of the horizontal column 9 there is fixed a rack 25 with which meshes a pinion of a motor unit 27 similar to the motor unit 1 5 fixed to the carriage 8.

The two arms are connected to a computer system 1 to which is connected a manual control box 30 for controlling the movement of the head 3, and a video keyboard 31; is is also provided with a control panel 32. This computer 1 is connected to the arms 2 by means of connection cables 33 which are only partially illustrated.

The electrical connections to the various motor units 15, 24, 27 and to the other component elements of the arm are provided by flat strips 35.

The carriage 4 is conveniently made of cast aluminium and is integral with the parts which guide the vertical column 5 along the z axis. This carriage 4 is positioned astride the element 6 and carries two pairs of support rollers 40 arranged with their axes horizontal above and below the element 6, and four pairs of guide rollers 41 having vertical axes and being positioned on the two sides of the element 6 at the top and bottom.

The vertical column 5 for the movement of the head 3 along the z axis is arranged to pass through the carriage 4 which serves to support and guide it. This column 5 is made of square section steel tube.

This carriage 4 in fact carries at the top and bottom two sets of four rollers 45 positioned perpendicularly with respect to the surfaces of the column 5 and in pairs adjacent opposite corners of this iatter. Within the column 5 there is positioned a single-acting balancing cylinder (of known type not illustrated) for preventing excessively high disturbing couples from being applied to the motor unit 24. The shaft of this cylinder is fixed at the top to the interior of the column 5 whilst the body is connected to the interior of a channel 52 fixed beneath the carriage 4. The cables and tubes for the movement along the y axis and for other components of the arm 2 all pass within the column 5. The carriage 8 which is fixed to the top of the column 5 serves as a support and guide for the horizontal column 9 which moves along the y axis.The carriage 8 is also made of cast aluminium and the column 9 is also made of square section steel tube. The carriage 8 also carries two pairs of four rollers 55 at the top and bottom adjacent the opposite corners of the column 9 and positioned perpendicularly with respect to the surface of the column 9 itself. A standardised flange 58 is carried at the end of the column 9 for receiving suitable gripper members, force sensors, and drive units, not illustrated, for controlling one or more of the rotations R,, R2 and R3. To obtain the rotations R1, R2 and R3 there is connected to the horizontal column 9, in the rear part thereof, a box which contains a motor unit including a d.c. motor and an incremental optical encoder keyed onto the motor shaft.This motor drives a reduction gearbox unit of the "harmonic drive" type which in turn drives a first toothed wheel which meshes with a second toothed wheel which is fixed to a sleeve passing within the column 9 and which projects out at the end as an attachment flange which is therefore subjected to the rotation R,. A bevel pinion/bevel wheel unit can be connected to this sleeve and can carry an attachment flange subjected to the rotation R3, or such bevel wheel can be fixed to a movable fork which is subjected to the rotation R2. These rotations R2 and R3 can alternatively be obtained by separate drive units contained in boxes attachable to the flange 58 at the front end of the horizontal column 9.

Between the flange 58 and the head 4 there can be provided a force sensor which detects (by means of inductive devices) the forces along the x and z axes exerted on the head 3 with respect to the support element 6 and comprising pairs of plates which are relatively movable against the action of resilient centring forces created by calibrated springs.

The arm 2 is not described in any further detail since it forms the subject of the invention described in Italian Patent Application No.

67647-A/81 by the same Applicant, the contents of which are incorporated herein by reference as far as necessary.

The computer system 1 for control of the system includes (Figure 2) a first central management computer 200 equipped for dialogue with the arm by means of the control panel 32, video keyboard 31 and a block 201 for the manual control of a plurality of items of equipment 202 (for example operating stations or devices supplying workpieces to the unit); the central computer 200 is equipped for the interpretation of programmes to be applied by connection with a memory block 203, and for the management of external equipment 202 by means of input and output members, for the reception of information from sensors on the arm 2, and for general supervision by possible connection to a further computer 200; and a second speciai purpose computer 210 for the control and monitoring of the movements along each individual linear and rotary axis of the arms 2 (with a limit of sixteen axes) under the supervision of the central computer 200 by means of on-line connection therewith. The computer 210 is connected to the box 30 for the manual control of the arms 2. The central computer 200 includes a microprocessor for example an LSl 11/2 and the computer 210 includes a microprocessor for example of the INTEL 8080 type.

The control panel 32 comprises three separate sections: a) a "power" section with push buttons including warning lamps for switching on the computer system 1, push buttons for switching off, and emergency push buttons for disabling the system whilst leaving it switched on; b) a "cycle" section with push buttons for starting and stopping the operating cycle, for continuing the cycle step by step, for stopping the arm 2 after completion of the working cycle and for zeroing the position of the arm; c) a "selectors" section for selecting operation under control of the computer 1, manual movement of the arm 2 using the box 30, and for changing the working speed of the arm 2.

The box 30 includes the following main elements: - a lever for the movement of the arm 2 along the x and y axes; - a lever for the movement of the arm 2 along the z axis and for controlling one of the available rotations (R1, R2, R3) in dependence on the position of a three-position rotary selector switch; - a data acquisition push button with incorporated warning lamp; - an acoustic indicator; - a three-position rotary selector which: in its left hand position turned in an anticlockwise sense enables movement along the z axis; in the central position enables the first rotation; in the right hand position turned in a clockwise sense enables the second rotation.

With reference to Figure 4 there is now described an assembly line for a component 300 (illustrated in Figure 5), formed according to the system of the present invention and comprising two arms 2 arranged laterally of a work bed 7 in the configuration illustrated in Figure 1. This component 300 is a plate valve for a compressor and comprises, in a known way, an induction flap valve 301; a valve plate 302, a delivery flap valve 303, a stop 304 for the valve 303, a seal 305, a body 306 and four screws 307.

With reference to Figure 4, at a station 310 the delivery flap valves 303 are stacked in an orientated manner in a vertical magazine; these are individually withdrawn by a pneumatically controlled device and carried in a predetermined orientation into the forward region of the station 310. At a nearby station 311 the stops 304 are similarly stacked in a vertical magazine and are individually withdrawn in the same way. At a following station 312 two channels transfer and position two rivets from a container to a rivetting machine which is actuated by a solenoid valve controlled by the computer system 1. At a nearby station 31 3 a slide conveys plates 302 from a vertical magazine to a forward region to be withdrawn. A following station 31 4 which conveys bodies 306 operates similarly.The seals 305 and the induction valves 301 are stacked in parallel stations 31 6 and 31 7 respectively. At a station 31 8 a four-way supply device transfers four screws 307 at a time to a pneumatic device which performs the screwing operation on the component 300.

The two arms 2 interact at a forward region 320 of the station 314' and perform independent operations in the other stations. The left hand arm 2 picks up the plate 302 from the station 31 3 and positions it exactly on the rivets at the station 31 2.

It then takes a discharge valve 303 from the station 310 and positions it exactly on the plate 302 in the station 312 and subsequently takes a stop 304 from the station 311 and deposits it on the valve 303 and plate 302. At the same time the right hand arm 2 picks up a seal 305 by suction from the station 316 and positions it on the body 306 which is positioned in the region 320 of the station 31 4. At this point the rivetting machine in the station 312 is actuated, then the left hand arm 2 picks up the completed unit from the station 312, turns it through 1 800 and then positions it on the seal 305 and on the body 306 in the station 320. Then the right hand arm 2 picks up an induction valve 301 by suction from the station 31 7 and positions it on the completed unit at the station 320.At this point the pincer of the right hand arm 2, combined with the suction action, grips the completed unit and positions it on the four screws 307 at the station 31 8. The screwing operation is then performed and the assembled component 300 is deposited on a conveyor 325.

The configurations of the production systems formed according to the present invention can differ widely from one another both in the number of arms 2 and in the form of each arm by the presence or absence of rotational axes and by the number and type of sensors used (force sensors on the head 3), position sensors on the pincers etc.); as well, naturally, as the type of gripper members and the external devices necessary for supplying and orientating the workpieces. The computer system 1 is able to follow the mechanical developments (up to sixteen axes distributed over several arms and in any combination of linear and rotary axes) to supervise the sensors, pincers and the external devices (equipment etc.) and to cope with all the requirements of complex applications.If a large number of arms are used it is possible to provide different units (with up to sixteen axes each) communicating with one another via the computers 200. The required productivity for a given application, the type and number of external devices for the supply and orientation of the components, and the connection requirements with the surrounding production environment all determine the number and arrangement around the assembly bed 7 of the arms 2. The arms 2 can be arranged in various ways to constitute automatic lines 400 (Figure 3a) in which the arms 2 are disposed on either side of the bed 7 along which passes a conveyor belt 401, or semiautomatic lines 402 (Figure 3b) in which there is a zone 405 of manual operations along the bed 7 and automatic cells 406 completely served by the arms 2 (Figure 3c), with equipment and machines operating on the workpieces etc.Such cells 406 can moreover be inserted in semi-automatic lines in which there can be zones 409 of manual activity (Figure 3d). As well as managing the arms 2 the computer system 1 also controls the operations of the various lines, equipment etc.

The production system, characterised by the use of modular units both at the level of the arms 2 (number of axes) and at an overall level (number of arms 2 utilised, type and number of sensors, degree of integration with other machines and devices) and by flexibility of use, is mainly used in the field of assembly for coupling, precision insertion, selectively taking up and depositing components, and for other technological operations typical of the assembly of components of small dimensions. The system can interface with automatic equipment specifically provided for the supply and orientation of components, with testing and measuring instruments, with special tools for technological operations to be performed on single components or assembled units.

Moreover, whenever required, tools and instruments can be inserted in the gripper member or substituted in place of it. The assembly constituted by the arms 2 and gripper members, equipment, tools and instruments is supervised by the computer system 1 according to a programme cycle. The computer system 1 is reprogrammable and can memorise different cycles both at the level of a single arm 2 and of the system overall.

For the extension of the inputs and outputs of the production system there are available the following three types of modules: sensor interface, equipment input and equipment output. These can be connected to the central computer 200 in various combinations up to a maximum of eight with no more than two modules committed to sensors.

As far as the programme is concerned this causes simultaneous movement along the linear and around the rotary axes of the various arms 2 with point-to-point control and with controlled acceleration and deceleration. The sensors used on the head 3 can be sensitive to the presence, for example of a workpiece, or force sensors. In the event of a workpiece failing to appear, or of the achievement of a predetermined threshold value, alternative programme segments can be activated, such as recovery or discharge cycles, or indication to the operator. The system programme allows the progress of several functions in parallel.

The programmer subdivides the complete cycle into parts which are performed almost in parallel, such parts comprising the cycle of individual arms 2, the cycles of individual automatic equipment blocks integrated in the system etc. The data necessary for the programme used are usually provided through a self-teaching phase. In this way the coordinates of the significant points, such as the take-up point and point of deposition, are learnt as well as the values of the sensors (dimensions of the workpieces to be manipulated for example); the programme used is stored in the core memory 203 and is transferred automatically to the computer memory 200 upon switching on.

During operation the microprocessors 200 and 210 perform a monitoring function on all the processor members for self diagnosis, stopping the movement of the arms if damage occurs.

According to the system of the present invention there is therefore provided a handling unit suitable for the assembly of small components using simple and reliable technological solutions at a reasonable price so as to be able economically to be inserted in the assembly sector.

The system of the present invention therefore has the advantage of being able to operate on different workpieces without the necessity for retooling; market fluctuations are thus satisfied by a flexible production system. It is advantageous for applications requiring frequently variable small batches and for medium volume production and medium variety (a truly flexible production system) and high volumes with little variety (flexible transfer lines).

It is also extremely useful in the production of workpieces of a wide variety of forms (bodies of revolution and prismatic bodies), and for coping with variations in dimensions and batch sizes, and with long and short working times. It is equally useful in more restricted working conditions where all the working functions, material and tool handling and working supervision is automated.

Finally, it is clear that the embodiments of the system of the present invention can be widely modified and varied without by this departing from the scope of the invention itself; for example the functions of the two computers 200 and 210 could be performed by a single computer.

Claims

1. An industrial production system characterised by the fact that it comprises a plurality of operating arms controlled by a computer system, each of the said arms comprising a support structure for a gripper end, the said structure including a single support and guide body for a single column, the said body being movable with respect to a support element for the said arm, the said support element being fixable on a fixed body, the said structure including rectilinear displacement means for the said end with respect to the said support element along the directions of a set of three orthogonal cartesian axes.

2. A system according to Claim 1, characterised by the fact that the said arm has a structure of individual components each of which is supported with respect to the other and with respect to the said support element by support means and is movable with respect to the other and to the said support element by means of the said rectilinear displacement means.

3. A system according to Claim 1 or Claim 2, characterised by the fact that the said structure includes a first individual carriage located astride and movable along the said support element by means of first of the said rectilinear displacement means, the said first carriage housing a first column passing therethrough and being movable along its own axis perpendicularly with respect to the said support element by means of second of the said rectilinear displacement means, and at or adjacent the top of the said first column therebeing fixed a second carriage housing a second column passing therethrough, this column being movable along its axis perpendicularly with respect to the first column and to the said support element by means of third of the said rectilinear displacement means, the said gripper or measurement end being positioned at or adjacent the end of the said second column.

4. A system according to any preceding Claim, characterised by the fact that the said rectilinear displacement means include guide elements directed along the said directions, and motor units.

5. A system according to any of the preceding Claims, characterised by the fact that the said structure includes rotary displacement means for permitting a rotation of the said gripper or measurement end around at least one of the axes coincident or parallel to the said set of three orthogonal cartesian axes.

6. A system according to any of the preceding Claims, characterised by the fact that it includes in the said arm a sensor for detecting the force of the movement of the said end along at least one direction.

7. A system according to any preceding Claim, characterised by the fact that it includes a pincer and/or a suction element at the end of the said arm.

8. A system according to Claim 7, characterised by the fact that it includes a position transducer for the movable elements of the said pincer.

9. A system according to any preceding Claim, characterised by the fact that it includes a single support element for a plurality of said arms.

10. A system according to any preceding Claim, characterised by the fact that the said support element is in the form of a beam.

11. A system according to any preceding Claim, characterised by the fact that the said computer system comprises a first central management computer for controlling devices external to the said arm, and a second specific computer subservient to the first, for the control and monitoring of the said rectilinear and/or rotary displacement means of the said plurality of said arms.

12. A system according to Claim 11, characterised by the fact that the said first computer includes a microprocessor of the LSI 11 type, and in that the said second computer includes a microprocessor of the INTEL 8080 type.

13. A system according to Claim 11 or Claim 12, characterised by the fact that it includes a panel for operative control of the said system connected to the said first computer, a device for the manual control of the displacement of the said ends of the said arms, connected to the said second computer, and a device for the manual control of the displacement of the said devices external to the said arms, connected to the said first computer.

14. A system according to any of Claims 11 to 13, characterised by the fact that the said external devices of the said arm include equipment and/or supply devices and/or machine tools.

1 5. A system according to any of Claims 11 to 14, characterised by the fact that it includes a plurality of said central management computers interconnected with one another for the monitoring and control of respective pluralities of said arms.

1 6. A system according to any preceding Claim, characterised by the fact that it is connected in an automatic and/or semi-automatic industrial assembly and/or production line.

17. A system according to any of Claims 1 to 15, characterised by the fact that it is connected in an automatic "cell" of an industrial assembly and/or production line.

1 8. A system according to any preceding Claim, characterised by the fact that the said computer system provides simultaneous monitoring and control of the said plurality of arms.

1 9. A system according to any preceding Claim, characterised by the fact that the said computer system operates, as selected, under automatic conditions, self-teaching conditions or manual displacement conditions.

20. An industrial production system served by a plurality of operating arms and controlled by a computer system, as described with reference to the attached drawings.