Numerical controller for correcting speed feedforward gain of machine

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First Claim
1. A numerical controller which controls a machine having a plurality of axes, the numerical controller comprising:
 a processor configured to;
store a plurality of correction coefficients for correcting a speed feedforward gain for speed feedforward control along a first axis of a plurality of axes in a memory, the plurality of correction coefficients corresponding to a plurality of coordinate values along a second axis of the plurality of axes, the plurality of correction coefficients for the first axis are computed by;
1) moving the machine along the first axis while increasing the speed feedforward gain to a maximum value free of vibration detected on the first axis while the machine is fixed at each of the plurality of coordinate values along the second axis,2) computing an adjusted value at each of the plurality of coordinate values along the second axis by adjusting the maximum value of the speed feedforward gain at each of the plurality of coordinate values along the second axis based on a normal value of the speed feedforward gain, and3) setting each of the plurality of correction coefficients as the adjusted value at each of the plurality of coordinate values along the second axis;
obtain the correction coefficient of the first axis corresponding to the current coordinate value of the second axis, based on Information stored in the memory,correct the speed feedforward gain for the speed feedforward control of the first axis by the obtained correction coefficient; and
control the first axis based on the corrected speed feedforward gain.
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Abstract
A numerical controller is provided with a speed feedforward gain correction unit configured to obtain an associated axis, which is subject to a varying load applied to a particular axis according to a coordinate value, and a correction coefficient of the particular axis corresponding to the current coordinate value of the associated axis, based on a correction coefficient storage unit, and correct a speed feedforward gain for speed feedforward control of the particular axis, and a motor control unit configured to control the particular axis based on the corrected speed feedforward gain.
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Current Assignee
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Sponsoring Entity
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5 Claims
 1. A numerical controller which controls a machine having a plurality of axes, the numerical controller comprising:
a processor configured to; store a plurality of correction coefficients for correcting a speed feedforward gain for speed feedforward control along a first axis of a plurality of axes in a memory, the plurality of correction coefficients corresponding to a plurality of coordinate values along a second axis of the plurality of axes, the plurality of correction coefficients for the first axis are computed by; 1) moving the machine along the first axis while increasing the speed feedforward gain to a maximum value free of vibration detected on the first axis while the machine is fixed at each of the plurality of coordinate values along the second axis, 2) computing an adjusted value at each of the plurality of coordinate values along the second axis by adjusting the maximum value of the speed feedforward gain at each of the plurality of coordinate values along the second axis based on a normal value of the speed feedforward gain, and 3) setting each of the plurality of correction coefficients as the adjusted value at each of the plurality of coordinate values along the second axis; obtain the correction coefficient of the first axis corresponding to the current coordinate value of the second axis, based on Information stored in the memory, correct the speed feedforward gain for the speed feedforward control of the first axis by the obtained correction coefficient; and control the first axis based on the corrected speed feedforward gain.  View Dependent Claims (2, 3, 4, 5)
1 Specification
This application is a new U.S. Patent Application that claims benefit of Japanese Application No. 2016231208, filed Nov. 29, 2016, the disclosure of this application being incorporated herein by reference in its entirety for all purposes.
The present invention relates to a numerical controller, and more particularly, to a numerical controller having a function of correcting speed feedforward by machine coordinate values of associated axes.
A machine such as a machine tool generally has a plurality of axes and machines a workpiece by controlling these axes. The machine tools shown in
In the machine shown in the upper part of
The machine shown in the upper part of
On the other hand, axes of the machine are driven by a motor that is controlled by a move command output by a control device. While the motor is controlled so as to move at a speed commanded by speed feedback control (speed control loop), speed feedforward control is further performed, as shown in
In some machine configurations, however, loads on the individual axes are not selfcontained and sometimes may vary depending on the positions of other axes. In the machine shown in the upper part of
Thus, in an environment where the loads on the axes vary, the delay in response of the speed control loop also varies due to the load variation. If the speed feedforward gain set for each axis is used as it is in the speed feedforward control, therefore, the motions of the individual axes cannot be aligned, so that the workpiece to be machined may suffer a shape error or the operation of the machine may be subject to vibration, in some cases.
Accordingly, the object of the present invention is to provide a numerical controller having a function of correcting speed feedforward by machine coordinate values of associated axes.
A numerical controller of the present invention has a function of registering, as associated axes, those axes which are associated with loads acting on individual axes and setting correction coefficients corresponding to machine coordinate values of the associated axes. The abovedescribed problems are solved by adjusting speed feedforward by multiplying a speed feedforward gain of an axis by the correction coefficients corresponding to the machine coordinate values of the associated axes, in speed feedforward control.
A numerical controller according to the present invention, which controls a machine having a plurality of axes, comprises a correction coefficient storage unit stored with an associated axis, which is one of the plurality of axes for a predetermined or particular axis among the plurality of axes and is subject to a varying load applied to the particular axis according to the coordinate value of the axis concerned, and a correction coefficient corresponding to the coordinate value of the associated axis for correcting a speed feedforward gain for speed feedforward control of the particular axis, in association with each other; a speed feedforward gain correction unit configured to obtain the correction coefficient of the particular axis corresponding to the current coordinate value of the associated axis, based on the correction coefficient storage unit, and correct the speed feedforward gain for the speed feedforward control of the particular axis by the obtained correction coefficient; and a motor control unit configured to control the particular axis based on the corrected speed feedforward gain.
The numerical controller according to the present invention further comprises an associatedaxis registration unit configured to register the associated axis for the particular axis into the correction coefficient storage unit.
The numerical controller according to the present invention further comprises a correction coefficient setting unit configured to set the correction coefficient corresponding to the coordinate value of the associated axis in the correction coefficient storage unit.
In the numerical controller according to the present invention, the correction coefficient setting unit commands the motor control unit to move the particular axis registered in the correction coefficient storage unit with the associated axis for the particular axis moved to a predetermined coordinate and obtains the correction coefficient in the predetermined coordinate for the associated axis by adjusting the speed feedforward gain of the particular axis while monitoring a feedback of the particular axis from the motor control unit. In the numerical controller according to the present invention, the correction coefficient storage unit is registered with a plurality of associated axes for each single axis, and the speed feedforward gain correction unit obtains the correction coefficient based on the respective coordinate values of the plurality of associated axes registered for the particular axis and corrects the speed feedforward gain for the speed feedforward control of the particular axis by the obtained correction coefficient.
According to the present invention, control can be performed in consideration of the influence from associated axes due to a machine configuration, and therefore, improvement of the machining shape accuracy can be expected.
The above and other objects and features of the present invention will be obvious from the ensuing description of embodiments with reference to the accompanying drawings, in which:
A nonvolatile memory 14 is constructed as a memory that is, for example, backed up by a battery (not shown) so that its storage state can be maintained even when the numerical controller 1 is turned off. The nonvolatile memory 14 is stored with a machining program read in through an interface 15 and a machining program (described later) input through the CRT/MDI unit 70. While the nonvolatile memory 14 is further stored with programs for machining program operation processing used to run the machining programs, these stored programs are expanded in the RAM 13 at the time of execution. Moreover, various system programs for performing edit mode processing and the like needed to create and edit the machining programs are previously written in the ROM 12.
The interface 15 is an interface for connecting the numerical controller 1 and external equipment 72 such as an adapter. The machining programs and various parameters are read in from the side of the external equipment 72. Moreover, the machining programs edited in the numerical controller 1 can be stored into an external storage means through the external equipment 72. A PMC (programmable machine controller) 16 controls peripheral devices (e.g., an actuator such as a robot hand for tool change) of the machine tool by outputting signals to them through an I/O unit 17 according to a sequential program stored in the numerical controller 1. Furthermore, on receiving signals from various switches on a control panel on the main body of the machine tool, the PMC 16 processes the signals as required and delivers them to the CPU 11.
The CRT/MDI unit 70 is a manual data input unit equipped with a display, keyboard and the like. An interface 18 receives commands and data from the keyboard of the CRT/MDI unit 70 and delivers them to the CPU 11. An interface 19 is connected to a control panel 71 equipped with a manual pulse generator and the like.
An axis control circuit 30 for controlling axes of the machine tool receives a movement command amount of each axis from the CPU 11 and outputs a movement command for the axis to a servo amplifier 40. On receiving this command, the servo amplifier 40 drives a servomotor 50 for moving the axis of the machine tool. The servomotor 50 for the axis has a pulse coder (not shown) builtin, and a feedback signal from this pulse coder is fed back to the axis control circuit 30 to perform feedback control. In the hardware configuration diagram of
A spindle control circuit 60 receives a spindle rotation command for the machine tool and outputs a spindle speed signal to a spindle amplifier 61. On receiving this spindle speed signal, the spindle amplifier 61 rotates a spindle motor 62 of the machine tool at a specified rotational speed, thereby driving a tool.
A position coder 63 is connected to the spindle motor 62 by means of gears, a belt or the like. The position coder 63 outputs feedback pulses in synchronism with the rotation of a spindle and the feedback pulses are read by the CPU 11.
The associatedaxis registration unit 100 is a function means for registering associated axes that are associated with loads on individual axes (hereinafter referred to as the particular axes). As for examples of axes associated with the particular axes, the axis associated with a particular axis X1 is the Caxis, and the axis associated with a particular axis X2 is also the Caxis, in the case of the machine shown in the upper part of
The correction coefficient setting unit 110 is a function means for setting a correction coefficient of a speed feedforward gain at an arbitrary machine coordinate value for the associated axes for the individual particular axes registered into the correction coefficient storage unit 200 by the associatedaxis registration unit 100. In the numerical controller 1 of the present embodiment, the correction coefficient of an appropriate speed feedforward gain is set by the correction coefficient setting unit 110 after it is obtained in advance by an experiment or the like. The correction coefficient of the speed feedforward gain can be obtained by a method in which the particular axes are activated with the associated axes located corresponding to predetermined machine coordinate values (A to J of
The speed feedforward gain correction unit 120 obtains the correction coefficient of the speed feedforward gain, based on the correction coefficient of the speed feedforward gain at the machine coordinate value of each of the associated axes for the individual particular axes stored in the correction coefficient storage unit 200 and the machine coordinate value of each servomotor 50 acquired from the motor control unit 130 (described later), and outputs the obtained correction coefficient to the motor control unit 130.
The motor control unit 130 is a function means that is implemented as the CPU controls the axis control circuit 30 shown in
According to the first embodiment described above, the speed feedforward gain is corrected according to the machine coordinate values of the associated axes for the particular axes that receive a varying load depending on the machine coordinate values of the associated axes, so that control can be performed in consideration of the influence from the associated axes due to the machine configuration, and therefore, improvement of the machining shape accuracy can be expected.
A numerical controller 1 according to a second embodiment of the present invention performs the correction of the speed feedforward gain of a particular axis in consideration of a plurality of associated axes in controlling a machine with the associated axes for the particular axis, as shown in the upper and lower parts of
An associatedaxis registration unit 100 of the present embodiment is configured to be able to register a plurality of associated axes for each individual particular axis. Moreover, a correction coefficient setting unit 110 of the present embodiment is configured to be able to set the correction coefficient described in connection with the first embodiment for each of the associated axes registered for the particular axis.
A speed feedforward gain correction unit 120 of the present embodiment obtains correction coefficients from the machine coordinate values of a plurality of associated axes, if any, for the particular axis and calculates the correction coefficient of the speed feedforward gain of the particular axis by multiplying the obtained plurality of correction coefficients. As shown in the upper part of
According to the second embodiment described above, the speed feedforward gain is corrected according to the machine coordinate values of the associated axes for the particular axes that receive a varying load depending on the machine coordinate values of the plurality of associated axes, so that control can be performed in consideration of the influence from the associated axes due to the machine configuration, and therefore, improvement of the machining shape accuracy can be expected.
A numerical controller 1 according to a third embodiment of the present invention performs the correction of the speed feedforward gain of a particular axis in consideration of a plurality of associated axes in controlling a machine with the associated axes for the particular axis. As shown in
An associatedaxis registration unit 100 of the present embodiment is configured to be able to register a plurality of associated axes for each individual particular axis, and moreover, to register some or all of a plurality of associated axes as a composite associated axis.
A correction coefficient setting unit 110 of the present embodiment is configured to be able to set the correction coefficient described in connection with the first embodiment for each of the associated axes registered for the particular axis. Moreover, the correction coefficient setting unit 110 of the present embodiment is configured to be able to set the correction coefficient for a combination of machine coordinate values of a plurality of associated axes that are registered as a composite associated axis. If the A and Caxes are registered as the composite associated axis for the machine with the configuration shown in
If a plurality of associated axes are provided for each particular axis, the numerical controller 1 according to the present embodiment obtains the correction coefficients from the machine coordinate values of the individual associated axes and calculates the correction coefficient of the speed feedforward gain of the particular axis by multiplying the obtained correction coefficients. Moreover, if the composite associated axis is provided for the particular axis, the numerical controller 1 according to the present embodiment calculates the correction coefficient of the speed feedforward gain of the particular axis by multiplying correction coefficients obtained from other associated axes by correction coefficients obtained based on the sets of machine coordinate values of the composite associated axis. As shown in
According to the third embodiment described above, the speed feedforward gain is corrected according to the machine coordinate values of the associated axes for the particular axes that receive a varying load depending on the machine coordinate values of the plurality of associated axes, and moreover, the machine coordinate value of another associated axis can be used to deal with the associated axes that apply a varying load to the particular axes. Thus, control can be performed in consideration of the influence from the associated axes due to the machine configuration, and therefore, improvement of the machining shape accuracy can be expected.
A numerical controller 1 according to a fourth embodiment of the present invention has a function of automatically setting a correction coefficient corresponding to the machine coordinate value of an associated axis for a particular axis. The hardware configuration of the numerical controller 1 of the present embodiment is the same as that of the first embodiment described with reference to
The correction coefficient setting unit 110 of the present embodiment automatically sets correction coefficients corresponding to the machine coordinate values of associated axes for particular axes registered in a correction coefficient storage unit 200 by an associatedaxis registration unit 100. The correction coefficient setting unit 110 obtains individual correction coefficients of the associated axes (including a composite associated axis) for a case where the associated axes are located corresponding to predetermined machine coordinate values (e.g., A to J of
The correction coefficient setting unit 110 of the present embodiment may be configured, in obtaining the correction coefficient of the speed feedforward gain, to command the motor control unit 130 to locate the associated axes corresponding to the predetermined machine coordinate values (e.g., A to J of
Moreover, the correction coefficient setting unit 110 may be configured to obtain the correction coefficient of the speed feedforward gain by another method. According to this method, the correction coefficient setting unit 110 commands the motor control unit 130 to activate the particular axes by moving the associated axes to their respective predetermined machine coordinate values (A to J of
The correction coefficient setting unit 110 of the present embodiment thus obtains correction coefficients for some typical machine coordinate values of the associated axes and covers the correction coefficients for the intermediate machine coordinate values by performing interpolation processing (straightline, linear, or curvilinear surface interpolation processing or the like). The correction coefficient setting unit 110 of the present embodiment may be configured to acquire from the motor control unit 130 the range of machine coordinate values in which the associated axes are movable and to automatically calculate the machine coordinate values at which the correction coefficients are obtained by, for example, dividing the range of the machine coordinate values into a predetermined number of equal sections.
While embodiments of the present invention have been described herein, the invention is not limited to the abovedescribed embodiments and may be suitably modified and embodied in various forms.