DE102009010859A1 - Processing instructions computing method for computerized numerical control machine tool, involves calculating multiple position interpolation values corresponding to position coefficients of position polynomial - Google Patents

Abstract

The method involves allocating a storage space for storing position commands, and reading a position matrix with preset elements. A transformation matrix is read with other preset elements, and multiple position coefficients of position polynomial are calculated. Multiple position interpolation values are calculated corresponding to the position coefficients. Speed polynomial and speed coefficients of the speed polynomial are calculated using the position polynomial. Multiple speed interpolation values are calculated corresponding to the speed coefficients.

Description

BACKGROUND OF THE INVENTION

Field of the invention

The The invention relates to a method for calculating conditioning commands for a numerically controlled system, more precisely, a Method of calculating conditioning instructions to one with high Order differentiable continuous polynomial for to prepare a numerically controlled system.

Description of the state of the technology

motion control is a nuclear technology in precision machine tools, and belong to the scope of application of motion control technology Industrial machines for position control or speed control, in particular CNC (Computerized Numerical Control = Computer-aided numerical control) machine tools with high precision Control operations.

In A motion control system are various software and hardware techniques integrated, whereby the costs, the stability, the frequency of use, maintainability, scalability and collaboration behavior software and hardware are important factors for evaluating a such system. Further, both the position and considers the speed of all spindles of a machine tool, to determine the control quality of the same.

at CNC machine tools is a CNC system in a machine tool built-in, and this system receives and calculates input data and then provides commands to control operating conditions, such as the spindle rotation, the replacement of cutting tools, the Cutting movement, the switching of a coolant switch etc., to realize the intended control operations.

While the work of CNC machine tools are original data (such as the geometric shape and contour curves) and corresponding Instructions supplied to calculate multiple interpolation values, in order to work on a not yet processed material an exact processing along a contour curve between a starting point and an end point perform.

The U.S. Patent 6,772,020 discloses an arrangement for generating command variables for control loops of a CNC machine tool having an interpolation unit for providing position set points with a defined interpolation scan rate, and with a precision interpolation unit. The precision interpolation unit has a scan rate converter and a downstream-connected low-pass filter, the precision interpolation unit being located downstream of the interpolation unit generating input-side command variables from input-side position setpoints for one or more downstream-connected control loops, the precision interpolation unit having a control loop scan rate command variable in one generated temporal pattern of the control loop. The command variables for the control loops are implemented using the structure of a second-order filter, and this is also designed to match the CNC machine tool. However, there is no higher order differentiability for resulting path curves. Because of the high complexity of the command generation arrangement, the practical application of such CNC machine tools is reduced.

SUMMARY OF THE INVENTION

Accordingly, becomes a method for computing conditioning instructions for rendering a high-order differentiable continuous polynomial for a numerically controlled system and for synchronization the commands between a servo driver and a control unit needed a higher level.

In order to achieve this object, a method of calculating edit commands for a numerically controlled system is provided such that a higher level controller provides position commands to a servo driver for driving a motor. Steps of the method are described as follows: First, a memory space for storing position commands is provided by the servo driver. Thereafter, a position matrix and a transformation matrix are read. The transformation matrix is multiplied by the position matrix to obtain multiple position coefficients of a Po position polynomial and several position interpolation values are calculated. In addition, a velocity polynomial and an acceleration polynomial can be obtained. Accordingly, the position commands for conditioning a high-order differentiable continuous polynomial for synchronizing the servo driver and the higher-level control unit are calculated.

It Please note that both the above general description as well as the following description are exemplary only and thereto are provided for further explanation of the claimed invention. Other advantages and features The invention will become apparent from the following description, the drawings and the claims become apparent.

BRIEF DESCRIPTION OF THE DRAWING

The As novel features of the invention are specifically described in set out in the attached claims. The invention itself, however, is best with reference to the following detailed To understand the description of the invention, in which an exemplary Embodiment of the invention with reference to the attached drawings.

1 Fig. 12 is a schematic view of communication between a higher-level control unit and a servo driver in an embodiment of the invention;

2 Fig. 12 is a schematic view for explaining the computation of rendering commands;

3 Fig. 10 is a flow chart illustrating the computation of rendering commands; and

4 FIG. 12 is a schematic view illustrating position commands transmitted from and scanned by the higher-level control unit to the servo driver. FIG.

DETAILED DESCRIPTION THE INVENTION

In The interaction with the attached drawings will become hereafter the technical content of the invention with reference to a preferred embodiment, not to be used to limit the scope of protection is described. All equivalent variations and modifications to the appended claims intended by this Claims to be covered.

Now Reference is made to the drawing figures to an embodiment to describe the invention in detail.

With reference to the 1 First, the communication between a higher-level control unit and a servo driver in the embodiment will be explained. As an example, the electrical system of a CNC machine tool is used. The control unit 10 a higher level periodically generates position data via a G-code interpretation unit (not shown). The control unit 10 a higher level is electric with a servo driver 20 and supplies pulse-shaped position commands θ (i) to them. The position commands θ (i) are transmitted via a transmission line between the control unit 10 a higher level and the servo driver 20 transfer. The control unit 10 a higher level and the servo driver 20 each have a serial communication interface 102 respectively. 202 for high speed. The period of the control unit 10 higher level rendering commands θ (i) is T (seconds), and the period by the servo driver 20 received position commands θ (i) is T (seconds). In addition, the sampling rate is one in the servo driver 20 installed digital signal processor (DSP) 204 H (seconds). If the period of the servo driver 20 received position commands θ (i) is 0.5 ms (T = 0.5 ms), is the sampling rate of the digital signal processor 204 0.05 ms (H = 0.05 ms). Accordingly, the digital signal processor provides 204 in 0.5 ms, nine interpolation values for a compensation of the position commands θ (i). Through the digital signal processor 204 is a command-conditioning unit 2042 and, further, a control loop 2044 is used to provide for conditioning the position commands θ (i) into a high order differentiable continuous polynomial.

Now on the 2 and 3 Reference is made, which is a schematic view for illustrating the preparation of processing commands or a flowchart thereto. In accordance with a detailed description for calculating edit commands, the procedure is as follows. First, by the servo driver 20 a storage room 2046 for storing position commands θ (i) is provided (S100), and the position commands θ (i) are supplied from the control unit 10 a higher level to the servo driver 20 transfer. The position commands θ (i) are stored in memory space using a first-in-first-out (FIFO) approach 2026 stored to form a position matrix with k on 1 element. The position matrix has an element θ (0) for the current position and k-1 elements θ (-1), θ (-2), θ (-3), ... and θ (k-1) for previous position elements , A position polynomial θ (n) of degree (k-1) is defined. Let K have the value 6, that is, the degree of the position polynomial θ (n) is 5 to illustrate the position polynomial θ (n) expressed as follows: θ (n) = a 5 · n 5 + a 4 · n 4 + a 3 · n 3 + a 2 · n 2 + a 1 · N + a 0 (Equation 1)

Thereafter, the position matrix is read with k-on-1 elements (S102). When k is 6, the position matrix has six elements which are the current position element θ (0) and elements θ (-1), θ (-2), θ (-3), θ ( -4), θ (-5) of the five previous positions. Thereafter, a transformation matrix M having continuous k on k elements is read (S104). The transformation matrix M is a matrix with constant elements and the elements of the transformation matrix M are determined according to the dimension of this transformation matrix M. Accordingly, the position polynomial θ (n) can be expressed as follows: θ (0) = a 5 · (0) 5 + a 4 · (0) 4 + a 3 · (0) 3 + a 2 · (0) 2 + a 1 · (0) + a 0 (Equation 2.1) θ (-1) = a 5 ·(-1) 5 + a 4 ·(-1) 4 + a 3 ·(-1) 3 + a 2 ·(-1) 2 + a 1 · (-1) + a 0 (Equation 2.2) θ (-2) = a 5 · (-2) 5 + a 4 · (-2) 4 + a 3 · (-2) 3 + a 2 · (-2) 2 + a 1 · (-2) + a 0 (Equation 2.3) θ (-3) = a 5 · (-3) 5 + a 4 · (-3) 4 + a 3 · (-3) 3 + a 2 · (-3) 2 + a 1 · (-3) + a 0 (Equation 2.4) θ (-4) = a 5 · (-4) 5 + a 4 · (-4) 4 + a 3 · (-4) 3 + a 2 · (-4) 2 + a 1 · (-4) + a 0 (Equation 2.5) θ (-5) = a 5 · (-5) 5 + a 4 · (-5) 4 + a 3 · (-5) 3 + a 2 · (-5) 2 + a 1 · (-5) + a 0 (Equation 2.6)

The above equations (Equation 1.2 to Equation 2.6) are expressed in matrix form as follows:

Also, the transformation matrix M is defined as follows:

Subsequently, k position coefficients of the position polynomial θ (n) are calculated (S106). The six position coefficients (k = 6), ie a ₀ to a _5, can be calculated by the transformation matrix M as follows:

Thereafter, a plurality of position interpolation values corresponding to the position polynomial θ (n) and the position coefficient are calculated (S108). The position commands θ (i) can be calculated by the position polynomial θ (n) of degree k-1. If i is an integer, the position commands θ (i) are positional data as read from a control unit 10 are transmitted at a higher level, and when i is not an integer, the position commands θ (i) are the position interpolation values. For example, nine position interpolation values are θ (-0.1), θ (-0.2), θ (-0.3) ... and θ (0.9), respectively, and the nine position interpolation values are between θ (0) and θ (-1).

In addition, a velocity polynomial ω (n) of degree k-2 and a plurality of velocity coefficients of the velocity polynomial are calculated by taking the first derivative of the position polynomial θ (n) (S 110). Equation 1 corresponds to the first derivative for calculating the velocity polynomial ω (n), ie ω (n) = dθ (n) / dn as follows: ω (n) = 5a 5 · n 4 + 4a 4 · n 3 + 3a 3 · n 2 + 2a 2 · N + a 1 (Equation 3)

After that become multiple speed interpolation values accordingly the velocity polynomial ω (n) and the velocity coefficient calculated (S112).

In addition, an acceleration polynomial α (n) of degree k-3 and a plurality of acceleration coefficients thereof are calculated by taking the first derivative of the velocity polynomial ω (n) (S114). Equation 3 is subjected to the first derivative to calculate the acceleration polynomial α (n), ie α (n) = dω (n) / dn, as follows: α (n) = 20a 5 · n 3 + 12a 4 · n 2 + 6a 3 · N + 2a 2 (Equation 4)

Finally For example, a plurality of acceleration interpolation values corresponding to Acceleration polynomial α (n) and the acceleration coefficient calculated (S116).

The position polynomial θ (n), the velocity polynomial ω (n) and the acceleration polynomial α (n) are in phase, whereby a servo delay between the control unit 10 a higher level and the servo driver 20 according to the equation 1, the equation 3 and the equation 4 is significantly reduced.

It will be on the 4 Reference is made, which is a schematic view of position commands as transmitted from and scanned by the higher-level control unit to the servo driver. Since the position commands θ (i) between the servo driver 20 and the control unit 10 are out of synch, the position polynomial θ (n) is modified to become a modified position polynomial θ (t) to the position commands θ (i) between the servo driver 20 and the control loop 2046 the control unit 10 to synchronize a higher level.

The variable n in the position polynomial θ (n) (Equation 1) is replaced by a variable t to obtain a modified position polynomial θ (t) (Equation 5), where t = Ta + n × Ts-Tc. applies. The modified position polynomial θ (t) is expressed as follows: x (t) = a 5 * (T) 5 + a 4 * (T) 4 + a 3 * (T) 3 + a 2 * (T) 2 + a 1 · T + a 0 (Equation 5) where Ta is the time at which the position commands θ (i) initially enter the control loop 2046 be transmitted; Ts is the timing of the position commands θ (i) as through the control loop 2046 be scanned; and Tc is the period of the position command θ (i) of the control unit 10 a higher level is.

Also, multiple sampled position commands x0, x1, ... x7 of the control loop 2046 according to of equation 5 are calculated.

In similar Way, a modified velocity polynomial ω (t) calculated by the modified position polynomial θ (t) is subjected to the first derivative, and it can also be a modified Acceleration polynomial α (t) are calculated by the modified velocity polynomial ω (t) of the first Derivative is subjected.

• 1. Die von der Steuerungseinheit einer höheren Ebene an den Servotreiber übertragenen Positionsbefehle können berechnet werden, um ein mit hoher Ordnung differenzierbares kontinuierliches Polynom aufzubereiten.
• 2. Das Positionspolynom, das Geschwindigkeitspolynom und das Beschleunigungspolynom sind in Phase, wodurch eine Servoverzögerung zwischen der Steuerungseinheit einer höheren Ebene und dem Servotreiber deutlich verringert ist.
• 3. Es ist einfach Positionskoeffizienten, Positionsinterpolationswerte, Geschwindigkeitskoeffizienten, Geschwindigkeitsinterpolationswerte, Beschleunigungskoeffizienten und Beschleunigungsinterpolationswerte entsprechend der Transformationsmatrix mit konstanten Elementen zu berechnen.
• 4. Es können mehrere Abtastpositionsbefehle der Regelungsschleife des Servotreibers berechnet werden, um die Positionsbefehle zwischen dem Servotreiber und der Steuerungseinheit einer höheren Ebene zu synchronisieren.

In summary, the invention has the following advantages:

• 1. The position commands transmitted from the higher level control unit to the servo driver can be calculated to prepare a high order differentiable continuous polynomial.
• 2. The position polynomial, the velocity polynomial and the acceleration polynomial are in phase, significantly reducing servo delay between the higher level controller and the servo driver.
• 3. It is easy to calculate position coefficients, position interpolation values, velocity coefficients, velocity interpolation values, acceleration coefficients, and acceleration interpolation values corresponding to the constant-element transformation matrix.
• 4. Multiple sense position commands of the control loop of the servo driver may be calculated to synchronize the position commands between the servo driver and the higher level controller.

Even though the invention with reference to its preferred embodiment has been described, it should be noted that the invention is not is limited to related details. In the above description, various substitutions and Modifications suggested and others will become apparent to those skilled in the art. Therefore, all such substitutions and modifications of Scope of protection in the appended claims be defined invention.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - US 6772020 [0006]

Claims (8)

Method of calculating conditioning instructions for a numerically controlled system comprising a control unit a higher level to provide position commands a servo driver for driving a motor, comprising following steps: (a) Provide storage space for Storing the position commands; (b) reading a position matrix with k on 1 element; (c) reading a transformation matrix with k on k elements; (d) calculating a plurality of position coefficients a position polynomial of degree k-1; (e) and calculating several Position interpolation values corresponding to the position polynomial and the position coefficient. Method according to claim 1, characterized by following steps: (f) calculating a velocity polynomial of degree k-2 and several velocity coefficients of the velocity polynomial by means of the first derivative of the position polynomial after the step (D); and (g) calculating a plurality of velocity interpolation values according to the velocity polynomial and the velocity coefficients. Method according to claim 2, characterized by following steps: (h) calculating an acceleration polynomial of degree k-3 and several acceleration coefficients thereof by means of the first derivative of the velocity polynomial after the Step (g); and (i) calculating a plurality of acceleration interpolation values according to the acceleration polynomial and the acceleration coefficients. Method according to claim 1, characterized in that the position matrix comprises k elements which consist of one element the current position and k-1 elements to previous position elements consist. Method according to claim 1, characterized in that that the position polynomial multiplied by the transformation matrix is to obtain the coefficients of the position polynomial. The method of claim 1, characterized in that the position polynomial is modified to produce a modified position polynomial for synchronizing the position commands between the servo driver and the control loop of the higher level control unit, the position polynomial being expressed as follows: θ (n) = a (K-1) · n (K-1) + a (K-2) · n (K-2) + a (K-3) · n (K-3) + ... + a 1 · N + a 0 ; and the variable n of the position polynomial is replaced by a variable t to obtain the modified position polynomial expressed as follows: θ (t) = a (K-1) · t (K-1) + a (K-2) · t (K-2) + a (K-3) · t (K-3) + ... + a 1 · T + a 0 where t = Ta + n × Ts-Tc, where Ta = time at which the position commands are initially transmitted to the control loop; Ts = time at which the position commands are sampled by the control loop; and Tc = period of the position commands of the higher-level control unit. Method according to Claim 6, characterized that the modified position polynomial is subjected to the first derivative to obtain a modified velocity polynomial. Method according to claim 7, characterized in that that the modified velocity polynomial of the first derivative is subjected to a modified acceleration polynomial receive.