DE2359817A1 - CONTROL UNIT, IN PARTICULAR FOR CONTROL DEVICES WITH PROGRAM CONTROL - Google Patents

Description

Control device, especially for control devices with program control The invention relates generally to the field of control devices such as numerical control devices, machine control units, etc., which are dependent working from programmed information to one or more controlled elements to move on a machine along a specific programmed path. The programmed Path is through a consecutive number of programmed information blocks Are defined.

The programmed information can have a number of positioning end points or generate a predetermined trajectory. The programmed Blocks of information in a continuous or in a discontinuous manner Way to be executed. The invention specifically creates a control device, to improve the accuracy with which the controlled elements of the particular Follow the path.

Typically, regulating devices can be either with or without a closed one Loop servo mechanism work. Although the subject of the present invention can be used in both of these cases, it is particularly important in the case of devices or devices can be used advantageously that do not have a servomechanism with a closed Have loop. In an effort to keep the cost to reduce, Many control devices have been developed that use an open loop exhibit. Due to inherent problems in maintaining the Positioning accuracy without the use of an active feedback loop were used to improve the positioning accuracy on an open loop system many techniques and circuits developed and elaborated. A common technique To improve accuracy, either one set of deceleration ranges (spans) or by providing for a delay in some other way, when the controlled element approaches a control endpoint, or by using a Changes the bank direction.

However, this attempted solution has various disadvantages.

First of all, there is obviously an increase in costs and an increase in the complexity of the system, thereby deteriorating the reliability will. Further, the technique discussed above normally creates a fixed cycle created for each span along the programmed path. The accuracy of any controlled or regulated position of an element is a function of many variables, for example the dynamic properties of the machine, the cutting process, environmental conditions etc; therefore, a fixed deceleration cycle must be so composed or composed that all possible conditions are taken into account. As a result, will the effectiveness or the degree of efficiency in the movement of the controlled element reduced.

In order to improve the technique outlined above, there are some control devices equipped with a device for measuring the positioning error, then this measured error is used for a correction. In a first case it becomes the measured position error / an immediately following programmed measuring span (span) added. However, this does not create the possibility of positioning errors to collect. This also does not contribute to the accuracy in the measuring span correct where the error originated. In another case after executing a programmed span of the measured Failure offered to a driver mechanism; the controlled item is then on moved to a more precise end position. Unfortunately, in many use cases this type of positioning cycle is impractical. For example, if a cutting process is running, there is no point going past an end point and then this one Correct endpoint.

To improve the accuracy with which a controlled element Following a programmed path, another technique is also known. at this system becomes a variety of adjustable according to the request of a programmer Switches selected, which then take effect during certain programmed measuring spans will. The person concerned measures the positioning error and provides an appropriate one Switch on this amount. In subsequent executions of a specific Measuring span, the measured error compensates the controlled position; this system however, there are also various disadvantages. First of all, it is necessary that the relevant Person intervenes in the process, measures the error and sets the switches. This Operation takes time, which need not be required. It is further impractical to compensate for any positioning margin. After all, the system is also fixed. It cannot be adapted to changes that occur during subsequent machine cycles appear.

The system of the present invention is similar to those previously outlined There are no disadvantages. In the device according to the invention is continuously a Compensation made, margin-by-margin, for all error conditions that the dynamic Change the properties of the machine. Although in the device according to the present Invention, slowdown margins can also be used, they are in the case of the one described preferred embodiment not used. Accordingly, the present Invention created a system, which is always at a constant fast Feed rate moved, so therefore the efficiency or effectiveness positioning is optimally designed.

According to one embodiment of the invention, the control device in connection with a control device, a measuring circuit and a driver device for the movement of a controlled element depending on an input signal operable, which signal represents a programmed increment of movement. The control device contains a first device which responds to the first occurrence of the input signal and responsive to movement of the controlled element to then provide a compensation signal to generate which is the difference between the programmed increment of movement and the movement actually performed by the element as determined by the measuring circuit is determined reproduces. The control device also contains a device those on the compensation signal and on the second occurrence of the input signal responds to modify the input signal as a function of the compensation signal and to generate a modified input signal at an output, which with connected to the driver device. The controlled element therefore moves in dependence of the modified input signal on an actual trajectory that is very close to the programmed trajectory or comes very close to it.

Further advantages and details of the invention emerge from the the following description of exemplary embodiments with reference to the drawing. 1 shows a general block diagram showing the basic components the adapting position compensation circuit reproduces; Fig. 2 the basic Components of the compensation circuit and an alternative possible application the subject matter of the invention; Figure 3 is a detailed block diagram of an embodiment shape according to the invention; 4 shows an alternative embodiment of the compensation signal generator; and FIG. 5 shows an alternative application of the adaptive positioning compensation circuit.

FIG. 1 represents a general block diagram of the subject matter of FIG present invention. The object of the invention is merely thereby restricted that three elements must be present. These elements exist a controlled element 10, a driver device 12 and an input signal on a line 14, which is typically generated in a control device 17. The driver device can be in any form, such as hydraulic, pneumatic, electric, etc.

Further, the controlled element 10 can consist of a single or from there are several elements responsive to the driver device 12, and these elements can be in one or more directions depending on one or more Actuating devices are moved within the driver device 12. In the end the input signal on line 14 represents a function of the particular control device represents in which the subject invention is used and this input signal can be generated using any of a number of possible known techniques will. The input signal represents and defines a command or control position a displacement amount according to which the controlled element is moved got to. The input signal can be an analog or a digital signal and it represents only a single signal in a sequence of many signals, which define a sequence of many programmed spans or positions, which together make up a complete operating cycle.

The input signal on line 14 reaches the input of an input modification circuit 16. At the beginning it is assumed that that at the other input 20 of the modification circuit 16 there is no input signal. It is further assumed that the input signal is only a single one of a multitude of input signals that make up a complete Define the operating cycle.

The circuit 16 therefore generates a command signal which is the input signal is equivalent to. The driver device 12 responds to the command signal and tries to do the controlled element 10 to move to a position indicated by said command signal or the input signal is being played back. However, there is no closed feedback loop is present and there is a change in the speed ranges or gauges may or may not be present, reaches the controlled element 10 not actually a position as defined by the input signal. The controlled element is most likely to run over the desired one Location beyond.

A measuring circuit 22 responds to the movement of the controlled element 10 and generates a home position signal, which is the actual position of the controlled Element reproduces the position assumed. A compensation circuit 18 responds the measuring circuit 22 and the modification circuit 16 and calculates the difference between the actual position of the controlled element and the desired position the same as it is represented by the input signal. This difference is represented by a compensation signal which is generated in the compensation circuit 18 is saved.

After the next occurrence of the input signal during a subsequent one Operating cycle, the compensation signal from the compensation circuit 18 is on the line 20 and is generated with the input signal in the input modification circuit 16 combined. As a result, a new command signal is generated which is used for the Furthermore, overrun or overshoot takes care of which during the earlier Execution of the input signal has occurred. The controlled element therefore takes an actual location that is very close to the target location, like this one the input signal is defined.

However, if the operating conditions or environmental conditions one Change in the dynamic properties or responsiveness of the controlled Have caused the element, or if for any other reason the controlled Element does not reach the desired position, the compensation circuit 18 again put into operation to eliminate the error in the position of the controlled element to calculate and to save a new compensation signal.

The circuits shown and described in FIG. 1 operate in iteratively, depending on the occurrence of the input signal. The position of the controlled element is accordingly regulated in an adaptive manner, see above so that it is continuously effected that the actual position is close to the target position within is adapted or corresponds to the repeatability of the machine0 It should be mentioned that that at the beginning an input variable on line 20 from the compensation circuit 18 ago was present. It will be seen in the following that the initial value of the signal on line 20 can be zero or some other particular value can. Regardless of this initial value of the signal, however, the basic one remains Working principle of the circuit the same.

Fig. 2 shows a block diagram of a possible embodiment the compensation circuit and also an alternative application of the adapting position compensation device. The control device 24 consists typically from a control device for a machine. There are in the prior art many examples of such control devices, for example the numerical rule facilities, cyclical control units, etc. Typically, a program is prepared here, which in a medium and in a code contains the information that a certain Path or a number of predetermined relative positions between a cutting tool and define a workpiece. The program also contains further information relative to the particular cutting process being performed.

The control device 24 queries the medium and translates the code programmed input signals on this medium. In Addiction The programmed input signals can be transferred from the control device by further Input variables can be modified, a cutting compensation, tool length compensation or manual input signals for setting the specific position of the controlled Play Elements. However, whether these are modified or not modified are, the control device generates an input signal on line 26, which represents a command position. Fig. 2 shows a typical application of the The subject of the invention in a machine with a plurality of axes of movement. The input signals on line 26 therefore consist of input variables for the Input modification circuits 28 and 30. These circuits generate command signals for the driver devices 32 and 34 corresponding to these, which are respectively the controlled Move elements 36 and 38 into positions corresponding to the corresponding input signals correspond. Measuring circuits 40 and 42 are assigned to the controlled elements, responsive to them to generate output position signals representing those of reflect the actual positions reached by the elements. A compensation circuit 44 is responsive to the measurement circuitry and contains two compensation signal generators 46 and 48. The Kompensationssignalgene generators 46 and 48 have inputs that respectively to the input modification circuits 28 and 30 and assigned to them respond to the measuring circuits 40 and 42 assigned to them. Any compensation signal generator responds to its input variable and generates a compensation signal, which the difference between the target position, represented by the command signal the input modification circuit, and that reached by the controlled elements Actual position reproduces, this actual position reproduced by the starting position signal will. The compensation signals are then stored in a memory device 50, whose outputs are connected to the modification circuits 28 and 30, and the Generate compensation signals when the input signal appears, which defines the just executed position of the controlled element.

At this point, two points should be emphasized. First, that the subject matter of the present invention regardless of the number of Input signals that are to be compensated apply. It can be either one or the other or a plurality of input signals or selected ones Compensate input signals from a variety of input signals in a similar manner. The changes that are required to match the selected number of input signals To be taken into account are obvious to the person skilled in the art.

Second, Figs. 1 and 2 show the possibility of compensation, which takes place every time the input signal occurs.

However, it is also obvious to the person skilled in the art that the compensation only after a predetermined number of times at certain time intervals or only once, depending on a signal occurring in a random sequence needs to be calculated, for example depending on a signal which a certain amount of position error or some other process condition indicates.

3 shows a detailed block diagram of an embodiment according to the invention within a control device 52. On line 54 are Input signals generated. For any programmed span or programmed Position, a number of input signals are provided that contain many information words represent. In addition, the input signals can have the absolute value of the programmed Represent the position or the increment of displacement between desired positions. For the sake of simplicity it is assumed that there is only one axis of motion, and that one of these information words also defines an increment of movement, to reach the next desired position of the controlled element 56. That input signal representing this word is stored in a position command memory 58, which is located in an input modification circuit 60. One Adder circuit 62 also located within modification circuit 60, has an input, which on the Output 64 of the position command memory 58 responds, and has a further input that connects to an output 66 of the Memory elements 68 within the memory device 70 respond.

A compensation command memory is also located within the modification circuit 60 72 located. This memory 72 responds to one of the input signals and sees a command signal to operate the adaptive position compensation circuit initiate. Instruction memory 72 can respond to any of a variety of input signals address, which depends on the desired function. He can, for example, on each occurrence of the address of the stored in the position command memory 58 Address the input signal. The memory 72 can also access a specific code respond under the control of the programmer to the adaptive position compensation circuit to activate and de-energize.

With simpler control units where the number of position commands and where position compensation is desired for each command finally, the compensation instruction memory can be omitted. In However, as shown in Fig. 3, the compensation command memory 72 generates a signal on the line 73 for an addressing circuit 74 in the memory device 70. The addressing circuit 74 operates to select an appropriate storage element from the storage elements 68 selects.

In principle, the entire circuit of Fig. 3 operates generally as as described earlier. It becomes an input signal with the compensation signal defined earlier connected to from the control device 52 to generate a command signal for a driver device 76. The driver device 76 is activated an actuator 78 which moves the controlled member 56 into a position, which closely corresponds to the input signal in the position command memory 58. To the Controlled element 56 is mechanically coupled to a measuring circuit 80 and this consists a transducer 82 and a position signal memory 84. The transducer 82 speaks on the movement of the controlled element and is sent to the position latch 84 connected, which stores a position signal that the actual increment the displacement performed by the controlled element 56. The compensation signal generator 86 is connected to an output 85 of the measuring circuit 80. The signal generator 86 contains a subtraction circuit 88, one input of which is connected to the output 85 and its other input to the command signal from the input modification circuit 60 responds. The subtracting circuit 88 operates in such a way that it receives the position signal subtracts from the command signal. The algebraic difference between the input quantities the subtraction circuit 88 is represented by a new compensation signal, which is transferred to the storage device 70 and in a suitable storage element is stored by the storage elements 68. The new compensation signal will then used to modify the subsequent occurrence of the input signal.

4 illustrates a modified embodiment of the compensation signal generator. 4, a compensation signal generator 90 is composed of a subtracting circuit 92 and an adding circuit 94. The subtracting circuit 92 has an input which is connected to the output 64 of the position command memory 58, and has a further input which is connected to the output 85 of the measuring circuit 80 is. The difference signal from the subtracting circuit 92 is matched with the signal at the output 66 from the storage device 70 in the adder 94. It will be accordingly generates a new command signal, which is generated from the compensation signal generator 90 and which is identical to the new compensation signal, which is generated by the compensation signal generator 86.

Fig. 5 illustrates an alternative application of the adapting position compensation circuit. In Fig. 5 is an apparatus for processing of an irregularly shaped workpiece generally illustrated. The detailed construction such a device is well known to those skilled in the art; they are also details of the construction for an understanding of the object of the invention is not required. A turntable 96 includes an irregularly shaped one Workpiece 98 and is actuated in the direction indicated by the arrow by a rotary actuator (not shown) in rotation. Each turn of the table turns into a number divided by angle increments, which are indicated figuratively by the radii 100 are.

A rotating cutting tool 102 is driven by a drive or a rotary actuator (not shown) is driven and is controlled on a Element 104 arranged in two directions along an axis of movement is movable, which runs through the center of rotation of the table 96. The controlled Element 104 is driven by an actuator 106 which is attached to a Driver circuit 108 is connected.

The driver circuit 108 is provided with an input modification circuit 110 which receives signals from an input signal memory 112. The input signal memory has a large number of storage locations. Depending on the number of machining passes, to which the workpiece must be subjected are one or more storage locations is present, corresponding to each of the angular increments of the rotation of the table 96. Furthermore, for each increment of the rotation of the table 96, the relative Predetermine the position of the cutting tool 102 in relation to the workpiece 98. These relative Positions are stored in the signal memory 112. When the table turns, speak the detector circuit 115 responds to the angular increments of the rotation and generates a Output signal for the input signal memory to select the appropriate input signal to select. This input signal, which represents a predetermined position, causes the cutting tool to move to a position that is very close to this corresponds. In practice using standard servo control techniques it is very difficult to machine a workpiece with the desired degree of accuracy. By using the adaptive position compensation technique according to the However, the present invention can be a satisfactory one accuracy using a relatively simple and inexpensive circuit.

A measuring circuit 114 responds to the trajectory of movement of the controlled Elements 104 and generates a position signal which indicates the actual position or location of the controlled element 104 reproduces. The position signal is received as an input variable to a compensation circuit 116, which has a compensation signal generator 118, a divider circuit 120 and a memory device 122. The compensation signal generator 118 operates in the manner described earlier and generates a compensation signal, which is the difference between the position signal and the command signal from the Input modification circuit 110 illustrates. The compensation signal gets through the divider circuit 120 and to the memory device 122. In this application example It doesn't need to be the location by the full amount during one to compensate for subsequent rotation of the table 96. The divider circuit 120 creates therefore the possibility of only compensating a certain amount of the compensation signal, for example half, a quarter, etc. during each revolution. During subsequent Revolutions accordingly becomes the compensation signal from the memory device and is generated with the input signal in the input modification circuit 110 connected to provide a command signal to use the cutting tool to move to a position closer to that of the desired position signal or the corresponding situation. In addition, during the subsequent Revolutions the positioning error is gradually reduced until the desired Accuracy is achieved.

Although the present invention is preferred in some details Embodiments are described and illustrated, and although some are preferred Embodiments have been described in detail, is the present invention not limited to these details. On the contrary, there are a number of Modifications and changes are possible without departing from the scope of the present invention.

All recognizable in the description and illustrated in the drawing Details are important to the invention.

Claims (10)

P a t e n t a n s p r ú c h e 1. Control device for use with a measuring circuit and a Driver device to cause a controlled element to cycle through a variety of distances or distances depending on a variety moved by input signals, these distances being a predetermined trajectory define, and wherein the measuring circuit generates position signals which the actual distance or display the distance by which the controlled element has moved, characterized in that the control device has the following facilities and features: a) a compensation signal generator (86) which responds to the occurrence of one of the input signals and responsive to the measuring circuit for generating a compensation signal which the difference between the actual distance over which the element was moved and the target distance over which the element is to move, reproduces; legs Storage device (70) connected to the signal generator for storing the compensation signals connected; and c) a modification circuit (60) interposed between the memory means and the driver device is switched and which is based on a subsequent occurrence of a the input signals respond to said input signal as a function of the compensation signal to change. 2. Apparatus according to claim 1, characterized in that the storage device has the following features and facilities: a) a large number of storage elements (68) responsive to the signal generator for storing the compensation signals; and b) an addressing circuit (74) based on the modifying circuit responds to select exclusively one of the memory elements e. 3. Apparatus according to claim 2, characterized in that the modifying circuit has the following devices and features: a) a position command memory (58), which is responsive to the input signal and stores first signals representing the Show the distance or the distance over which the controlled element is located should move; b) an adder circuit (62) whose inputs are based on the first signals and address the plurality of storage elements and output them to the driver device is connected to a command signal as a function of the sum of the input quantities produce; and c) a compensation command memory (72) which is responsive to the input signals responds, and whose output is connected to the addressing circuit to second Store signals that define the input signals to be compensated. 4. Apparatus according to claim 3, characterized in that the signal generator further includes a subtracting circuit (88) to separate the position signal from the command signal subtract, so that the compensation signal arises, which the algebraic Represents the difference between the position signal and the command signal. 5. Apparatus according to claim 4, characterized in that the signal generator includes a divider circuit (120) connected between the memory device and the Signal generator is connected to the compensation signal by a predetermined Allocate amount down. 6. Control device for use in connection with measuring circuits and a number of driver devices for controlling a number of controlled ones Elements that move cyclically over a variety of distances or stretches in Dependent on a variety of input signals intended to remove, each the measuring circuits generate an output signal which represents the actual distance, over which one of the movable elements has moved, characterized in that, that the control device has the following facilities and features: a) one on each Occurrence of each of the input signals and responsive to each of the measurement circuits Means to generate a compensation signal which is the difference between the actual distance taken by an element as a function of an input signal has been covered, and the target distance that the element covers in a controlled manner should, reproduces; b) a device for generating the compensation signal connected circuit for storing each of the compensation signals; and c) one connected between the storage device and the plurality of driver devices Circuit responsive to the subsequent occurrence of each of the input signals, the subsequent occurrence of each of the input signals as a function of a corresponding one To modify the compensation signal. 7. Device for use with a control device, measuring circuits and a plurality of driver devices to thereby generate a number of controlled elements controlled and cyclical over a large number of routes depending on one Plurality of input signals to move or guide, each of the measuring circuits an output signal is generated which represents the actual distance traveled by one of the movable elements has been covered, characterized in that that the control device has the following devices and features: a) a storage device for storing a plurality of previously determined compensation signals, wherein each compensation signal is the difference between a desired shift, as defined by an occurrence of an input signal, and an actual one Represents displacement achieved due to a corresponding output signal or is defined; b) a multitude of circuits that result in a subsequent Occurrence of the input signals and respond to the compensation signals to command signals generate at outputs connected to the driver device; and c) a multitude of circuits which act on the measuring circuits and which the compensation signals responding generating device to new compensation signals depending on a subsequent occurrence of the input signals. 8. Control device for use in conjunction with a measuring circuit and a driver device to a controlled element controlled and cyclically via a Variety of routes depending on a variety of input signals too move, said routes defining a certain path, and where the measuring circuit generates position signals, which the actual distance, which of the controlled element has been covered, characterized in that the device has the following facilities and features: a) one on the occurrence one of the input signals and responsive to the measuring circuit circuit to a the difference between the actual distance covered by the element, and the target distance that the element covered in a controlled manner intended to generate reproducing compensation signal; b) a storage device, which is connected to the aforementioned circuit to generate the compensation signals save; and c) one connected between the memory circuit and the driver device Circuit responsive to a subsequent occurrence of one of the input signals, to modify the input signal as a function of the compensation signal. 9. Apparatus according to claim 5, characterized in that the generating Circuit has the following features and facilities: a) one on the input signal responsive circuit to store the first signals that reflect the route, over which the controlled element should move; b) a circuit with inputs, responsive to the first signals and the plurality of storage elements, and which has an output connected to the driver device to function as to generate a command signal from the sum of the input variables; and c) one on the Input signals responsive circuit with an output connected to the selecting Circuit connected to store second signals representing those input signals define which are to be compensated. 10. Apparatus according to claim 9, characterized in that the device includes a circuit for subtracting the position signal from the command signal, in order to generate the compensation signal which corresponds to the algebraic difference between represents the position signal and the command signal.