METHOD AND APPARATUS FOR SETTING COORDINATE SYSTEM

Abstract: A figure on a drawing DR placed on the read-out area TRA of a tablet is entered with a coordinate designating device by designating a plurality of points on the drawing, and at the same time a coordinate system of the figure is set and entered. To carry out the above coordinate setting, a first point Pt on the drawing DR is designated by the coordinate designating device to enter the coordinates of the first point Pt on a tablet coordinate system X t -Y t , and coordinates of the designated first point Pt on an NC data coordinate system X n -Y n are entered through a keyboard to set a reference point of the NC data coordinate system. A second point Pt′ on a straight line passing through the first point Pt parallel to an X-axis or Y-axis of the NC data coordinate system X n -Y n is designated by the coordinate designating device to enter the coordinates of the second point Pt′ on the tablet coordinate system. The NC data coordinate system can be set and entered by employing the first and second points and the coordinates on the tablet coordinate system. An embodi­ ment of the present invention may provide a method and apparatus for effecting the foregoing coordinate setting process. The reference point of the NC data coordinate system can easily be established, and it can be set and entered even when the reference point is located outside the read-out area of the tablet.

Description: METHOD AND APPARATUS FOR SETTING COORDINATE SYSTEM The present invention relates to a method and apparatus for setting a coordinate system, and more particularly to such a coordinate system setting method and apparatus particularly for use in entering graphics employing a tablet. A numerically controlled machine tool (hereafter referred to as an NC machine tool) is operated in a manner specified by a machining program stored on an NC tape to subject a workpiece to prescribed machining. To create an NC tape for a cutting operation, numerical control information and other machining conditions are punched into a paper tape in accordance with predetermined rules. The numerical control information includes all the data necessary for machining, such as numerical values obtained from a design drawing and relating to the dimensions of the workpiece that is to be machined, feed speed, and the like. When machining the workpiece by means of an NC machine tool, the NC tape which has been prepared is fed into the tape reader of a numerical control device so that the various instructions recorded on the NC tape may be read successively, the numerical control device responding by executing the read instructions to cause the machine tool to machine the workpiece as prescribed. Since considerable time and experience is required to create the information stored on an NC tape, an apparatus for preparing an NC tape automatically has recently been developed and-put into practical use. The apparatus includes a graphic display, keyboard and printer and is extremely useful in preparing NC tapes in a simple, accurate and rapid manner. Such an apparatus for automatically preparing NC tapes is constituted by a microcomputer with its internal main memory for storing the NC tape preparation software, or system program. To create a machining program by means of the above-described apparatus, the prescribed system program is loaded into the main memory, and a so-called "part program" consisting of a group of data specifying the contour of a part, namely the path of a tool for cutting the contour, maust be created and entered in accordance with predetermined rules. The preparation of such a part program is troublesome. and time-consuming, and can only be accomplished by a programmer having considerable programming skill. With these difficulties in view, there has been a demand for a system capable of entering graphics simply by specifying a plurality of points on such graphics, and attention has turned to a graphic entering apparatus employing a tablet. Such a graphic entering apparatus using a tablet can easily enter graphics even if the dimensions thereof are unknown. However, it has been troublesome to set and enter an NC data coordinate system. No NC data coordinate system can be established and entered particularly when a drawing is greater in size than the read-out area of a tablet with the reference point on the NC data coordinate system being located outside the read-out area. According to one aspect of the invention there is provided a method of setting a coordinate system of a figure on a drawing laid on the read-out area of a tablet and entering the figure with a coordinate designating device by designating a plurality of points on the drawing, said method comprising the steps of: : designating a first point on the drawing with the coordinate designating device to enter the coordinates of the first point on a tablet coordinate system; entering coordinates of the first point on a numencalcontrol data coordinate system through an input device to set a reference point of the numerical control data coordinate system; designating a second point on a straight line passing through said first point parallel to an X-axis or Y-axis of said numerical control data coordinate system to enter the coordinates of the second point on the tablet coordinate system; and setting the numerical control data coordinate system by employing said first and second points and the coordinates on the tablet coordinate system. According to another aspect of the invention there is provided an apparatus for setting a coordinate system of a figure on a drawing, comprising: a tablet having a read-out area for placing the drawing thereon; a coordinate designating device for designating a plurality of points on the figure to enter coordinates thereof; a first register for storing the coordinates of a first point on the figure on a tablet coordinate system; a second register for storing the coordinates of a second point on the tablet coordinate system; a third register for storing the coordinates of said first point on a numerical control data coordinate system; a fourth register for storing the coordinates of a third point on the tablet coordinate system which are entered through said tablet; and a coordinate transformation unit for effecting arithmetic operations of coordinate transformation on the coordinates of said third point to generate coordinates on the numerical control data coordinate system. An embodiment of the present invention may provide a method and apparatus capable of easily setting and entering an NC data coordinate system. An erlbodiment of the present invention relay further provide a method and apparatus capable of easily setting an NC data coordinate system even when no dimensions are known, and of setting and entering the reference point of an NC data coordinate system in case the reference point is located outside the read-out area of a tablet. In one embodiment o, / figure on a drawing placed on the read-out area of a tablet is entered with a coordinate designating device by designating a plurality of points on the drawing, and at the same time a coordinate system of the figure is set and entered. To carry out the above coordinate setting, a first point on the drawing is designated by the coordinate designating device to enter the coordinates of the first point on a tablet coordinate system, and coordinates of the designated first point on an NC data coordinate system are entered through a keyboard to set a reference point of the NC data coordinate system. A second point on a straight line passing through the first point parallel to an X-axis or Y-axis of the NC data coordinate system is designated by the coordinate designating device to enter the coordinates of the second point on the tablet coo#nate system. The NC data coordinate system can be set and entered by employing the first and second points and the coordinates on the tablet coordinate system. The above and other features and advantages an example of of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram illustrative of the principles of the present invention; Fig. 2 is a block diagram of a system for reducing the present invention to practice; Fig. 3 is a perspective view of the general features of a system for creating NC data; Fig. 4 is a perspective view of a tablet input device in the system shown in Fig. 3; and Fig. 5 is an enlarged, top view of a cursor unit included in the device of Fig. 4. Fig. 1 is explanatory of operations of establishing an NC data coordinate system. First, the reference point Rm of the coordinate system is set up in the following order: (a) A point Pt on a read-out area TRA and a drawing DR is designated by a coordinate designating device, and the coordinates (xt, yt) thereof on a tablet coordinate system are entered; (b) The coordinates (xn, yn) of the designated point Pt on an NC data coor dinate system are entered through a keyboard. After the reference point of the NC data coordinate system has been determined by the foregoing steps (a) and (b), then coordinate axes are established in the following manner: (a) Where the tablet coordinate system Xt - Yt and the NC data coordinate system Xn - Yn are in parallel relationship to each other, a key on the keyboard is depressed to indicate the fact that the both coordinate systems are parallel; or (b) Where the coordinate systems Xt - Yt and Xn - Yn are not parallel to each other, a "+ " or "-" key is depressed and then a point Pt' on a straight line passing through the point Pt parallel to the X-axis on the NC data coordinate system Xn - Yn in a direction dependent on the sign "+" or "-" is designated by the coordinate designating device to enter the coordinates (xt', yt') of the point Pt' on the tablet coordinate system. The NC data coordinate system is thus set up by the foregoing procedure. Other processes than the above may be considered for setting coordinate axes. For example, a coordinate system can be established by designating a point on a straight line extending through the point Pt parallel to the Y-axis. Actuation of the "+" or "-" key may not necessarily be required. After the NC data coordinate system has been set up, any arbitrary point Q on the drawing is designated by the coordinate designating device, and the coordinates (xq, yq) of the point Q on the tablet coordinate system can converted into corresponding coordinates (xm, ym) on the NC data coordinate system through the following coordinate transformation: EMI8.1 where EMI8.2 Fig. 2 is a block diagram of a system for reducing the present invention to practice. The apparatus includes a first register 101a for storing the cooridnates (xt, yt) of the point Pt on the tablet coordinate system, a second register lOlb for storing the coordinates (xt', yt') of the point Pt' on the tablet coordinate system, and a third register lOlc for storing the coordinates (xn, yn) of the point Pt on the NC data coordinate system. When the coordinates xq, yq of the point Q (Fig. 1) on the tablet coordinate system is entered from a tablet input device 102 into a fourth register lOld, a coordinate transformation unit 103 effects the arithmetic operations defined by the equations (1) and (2) to generate coordinate values xm, ym on the NC data coordinate system. An NC data creating unit 104 employs the coordinate values xm, ym to generate NC data which are then stored in a data memory 105. Fig. 3 is a perspective view of a system for creating NC data in which a method of setting a coordinate system of the present invention can be incorporated. The system includes the main body 11 of an apparatus for creating NC data. The main body 1 comprises a keyboard lla having a pultiplicity of keys, a graphic display device llb, a magnetic tape unit llc, a printer lld, and a control unit, not shown. The latter is constituted by a microcomputer which executes processing for the input and output of information, for digitizing and for the creation of NC data, all executed by means of the tablet described hereinbelow, based on a system program stored previously in memory means such as a ROM (read-only memory). The multiplicity of keys provided on the keyboard lia are used by the operator for instructing operations to be performed through conversational interaction, for designating system program loading, and for entering NC data. The graphic display device llb displays, in graphical form, coordinate values obtrained by digitization of positions designated by the tablet, as well as input, numerical values, NC data and various messages or prompts for conversational interaction with the operator. The magnetic tape unit llc is used to enter a system program into the main body of the NC data creating apparatus 11. By way of example, when using a tablet to enter coordinate values directly from a drawing and prepare NC data, the software (system program) for digitizing processing must be fed into the main body 11. This is done by loading the digitizing program from a magnetic tape cassete set in the magnetic tape unit llc into the main body 11. To read the tape into the system, the operator need only touch a load button on the keyboard lla after the tape cassette has been set in the magnetic tape unit llc. The printer lld is adapted to print out characters which appear on the screen of the graphic display device llb, data punched in a paper tape, described later, and information which has been written into the loaded magnetic tape. The system also includes a paper tape reader/puncher 12 for preparing an NC tape by punching a paper tape with perforations indicative of the NC data prepared by the main body 11, and for reading NC or other data which has already been punched into an NC tape. The system tablet, designated at 13, comprises a board which uses the principle of electromagnetic induction to enter data. By relying upon a coordinate designating device such as a cursor unit or stylus pen as means for designating coordinates, the tablet 13 is operable to input positional coordinates from a drawing laid on the tablet surface, these coordinates being fed into the main body 11 as an input thereto. The system tablet 13 corresponds to the tablet input device 102 shown in Fig. 2. Fig. 4 shows in perspective the tablet 13 in greater detail. The tablet 13 comprises a tablet main body or board 13a, a tablet cover 13b, a cursor unit 13c, a stylus pen 13d, a buzzer 13e, a group of lamps 13f indicating, e.g., coordinate input mode and introduction of power, an input/output connector 13g for connecting the tablet 13 to the main body 11, a power unit 13h for supplying hte table body 13a with D.C. power, an A.C. cable 13i, a D.C. cable 13j for connection between the tablet body and power unit, and a pen stand 13m for holding the stylus pen 13 when not in use. The cursor unit 13c or stylus pen 13d is used to enter coordinate and other data. The details of the cursor unit 13c are illustrated in the enlarged view of Fig. 8, in which a top view of the cursor unit is shown. The cursor unit 13c has a main body CSB, first and second switches SW1, SW2, a position reader PER , a connector CNT and a cable CBL leading from the connector CNT to the main body CSB. To enter the coordinates of a point, the intersection Pc of the cross hairs provided on the position reader PR is aligned with the desired opint on a drawing laid on the tablet body, followed by depressing the first switch SW1 or the second switch SW2. embodiment of the According to the present/invention, the reference point of an NC data coordinate system can easily be established, and it can be set up and entered even when the reference point is located outside the read-out area of the tablet. Although a certain preferred embodiment has been shown and described, it should be understood that many changes and modifications may be made therein without departing from the scope of the appended claims. Ingenal terms, a figure on a drawing DR placed on the read-out area TRA of a tablet is entered with a coordinate designating device by designating a plurality of points on the drawing, and at the same time a coordinate system of the figure is set and entered To carry out the above coordinate setting, a Pt DR first point/on the drawing/is designated by the coordinate designating device to enter the coordinates of the first Pt Xy-Yt point/on a tablet coordinate system/, and coordinates of the Pt Xn-Yn designated first point/on an NC data coordinate system/are entered through a keyboard to set a reference point of the Pt' NC data coordinate system. A second point/on a straight line passing through the first point/parallel to an X-axis or Y-axis of the NC data coordinate systems designated by the coordinate designating device to enter the coordinates of the second pointAón the tablet coordinate system. The NC data coordinate system can be set and entered by employing the first and second points and the coordinates An embodiment of on the tablet coordinate system./ the present invention may provide a method and apparatus for effecting the foregoing coordinate setting process; The reference point of the NC data coordinate system can easily be established, and it can be set and entered even when the reference point is located outside the read-out area of the tablet.

Claims: What we claim is: 1. A method of setting a coordinate system of a figure on a drawing laid on the read-out area of a tablet and entering the figure with a coordinate designating device by designating a plurality of points on the drawing, said method comprising the steps of: designating a first point on the drawing with the coordinate designating device to enter the -coordinates of the first point on a tablet coordinate system; entering coordinates of the first point on a numerical control data coordinate system through an input device to set a reference point of the numerical control data coordinate system; designating a second point on a straight line passing through said first point parallel to an X-axis or Y-axis of said numerical control data coordinate system to enter the coordinates of the second point on the tablet coordinate system; and setting the numerical control data coordinate system by employing said first and second points and the coordinates on the tablet coordinate system. 2. A method according to claim 1, wherein said reference point of the numerical control data coordinate system can be established outside the read-out area of the tablet. 3. An apparatus for setting a coordinate system of a figure on a drawing, comprising: a tablet having a read-out area for placing the drawing thereon; a coordinate designating device for designating a plurality of points on the figure to enter coordinates thereof; a first register for storing the coordinates of a first point on the figure on a tablet coordinate system; a second register for storing the coordinates of a second point on the tablet coordinate system; a third register for storing the coordinates of said first point on a numerical control data coordinate system; a fourth register for storing the coordinates of a third point on the tablet coordinate system which are entered through said tablet; and a coordinate transformation unit for effecting arithmetic operations of coordinate transformation on the coordinates of said third point to generate coordinates on the numerical control data coordinate system. 4. An apparatus according to claim 3, further including a unit for creating numerical control data from the coordinates of said last-mentioned coordinates generated by said coordinate transformation unit, and a memory for storing said numerical control data.

Inventors: KISHI, HAJIMU, SEKI, MASAKI, TANAKA, KUNIO
Applicants: FANUC LTD
Application year: 1983
Main classification: G06F3
IPC codes: G06F3, G05B19, G06K11