JP2018085058A - State estimation device, state estimation method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To estimate a state of an actuator that acts force on an object with high accuracy.SOLUTION: A cutting processing device 1 comprises a state estimation part 52. The state estimation part 52 estimates a state of an actuator based on an equation of motion in space composed of 2 or more mutually independent modes, which is a space converted from an n-inertia model indicating the actuator based on a parameter indicating internal information of a cutting processing device 1 as the actuator.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a state estimation device, a state estimation method, and a program.

2. Description of the Related Art Conventionally, in a machine tool that performs machining such as cutting or plasticity, a machining force is estimated for the purpose of monitoring a machining process.
For example, Patent Document 1 describes a technique for estimating a frictional force in polishing or the like with reference to a drive current of an actuator (motor) without using a force sensor.

Japanese Patent Laid-Open No. 11-285970

However, in the technique of estimating the machining force that largely depends on the current information of the motor including the technique described in Patent Document 1, an accurate machining force is obtained in a region below the static frictional force between the tool and the workpiece. The estimation accuracy of the machining force was not sufficient, such as being difficult to estimate.
Such a situation can occur not only in machine tools but also in actuators that apply force to objects such as rolling mills and robots.
That is, in the prior art, it is difficult to accurately estimate the state of the actuator that applies a force to the object.

  An object of the present invention is to estimate the state of an actuator that applies force to an object with higher accuracy.

In order to solve the above-described problem, a state estimation device according to one aspect of the present invention includes:
A state estimation device that estimates the state of an actuator that applies force to an object,
Based on an equation of motion in a space converted from an n-inertia model representing the actuator based on a parameter representing internal information of the actuator, the space being constituted by two or more independent modes It is characterized by comprising state estimation means for estimating the state.

  According to the present invention, the state of an actuator that applies a force to an object can be estimated with higher accuracy.

It is a mimetic diagram showing the main composition of the cutting device which is one example of application of the present invention. It is the schematic diagram which represented the cutting apparatus shown in FIG. 1 as a 2 inertia model. It is a schematic diagram which shows the concept of the mode conversion in this invention. It is a mimetic diagram showing the composition of the cutting device concerning one embodiment of the present invention. It is a block diagram which shows the hardware constitutions of a controller. It is a functional block diagram which shows the functional structure of the controller of a cutting device. It is a flowchart which shows the flow of the cutting force estimation process which the controller of a cutting device performs. It is a figure which shows an example of the estimation result of the cutting force at the time of the side surface processing by an end mill. It is a figure which shows an example of the estimation result of the cutting force at the time of changing the cutting amount. It is a schematic diagram which shows the concept of mode conversion of a 3 inertia model.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Basic concept of the present invention]
The present invention relates to a fully-closed control device that applies force to an object, and n-inertia models (n is an integer of 2 or more) defined by referring to information that can be acquired as internal information of the device. The state of the apparatus is estimated by a motion equation based on the plurality of modes.
Here, in the present invention, a rigid body mode for estimating the force component from the center of gravity movement of the machine element and a vibration mode for estimating the force component from the relative movement between the machine elements are defined as a plurality of modes.
In the equation of motion based on the plurality of modes, the position is expressed in a specific coordinate system converted from the coordinate system of the three-dimensional space, and the coefficient corresponding to the specific coordinate is used as the coefficient of the equation of motion.
That is, in the present invention, a predetermined space (hereinafter referred to as “mode space”) is defined, and the state of the apparatus is estimated by the equation of motion in the mode space, thereby realizing more accurate estimation. .
Hereinafter, the process of deriving the equation of motion in the mode space will be described.

[Derivation of equation of motion in mode space]
FIG. 1 is a schematic diagram showing a main configuration of a cutting apparatus 1 as an application example of the present invention.
As shown in FIG. 1, the cutting apparatus 1 includes a motor 2, an encoder 2 </ b> A, a coupling 3, a ball screw 4, a bearing 5, a stage 6, a linear scale 7, and a processing tool 8. ing. In FIG. 1, for convenience of explanation, a two-inertia model having a movement of the rotation system of the motor 2 and a translational movement of the stage 6 will be described as an example.

The motor 2 generates a motor torque corresponding to the input current Ia and rotationally drives the screw shaft of the ball screw 4 via the coupling 3.
Encoders 2A detects the stage position x _m as calculated from the rotation angle of the motor 2, and outputs the position x _m to a controller (not shown). Hereinafter, the stage position x _m calculated from the rotation angle of the motor 2 is also referred to as “converted movement amount x _m ” as appropriate.
The coupling 3 connects one end of the rotating shaft of the motor 2 and one end of the screw shaft of the ball screw 4.
In the ball screw 4, both ends of the screw shaft are rotatably supported by bearings 5, and a nut is fixed to the stage 6. The ball screw 4 translates the rotary motion transmitted from the motor 2 into a linear motion, thereby translating the stage 6 along the screw axis.
Hereinafter, a direction parallel to the screw axis of the ball screw 4 (lateral direction in FIG. 1) is referred to as an “x direction”.

The bearing 5 rotatably supports the screw shaft of the ball screw 4.
The stage 6 is loaded with a workpiece W that is an object of cutting, and is moved in the x direction by the ball screw 4.
Linear scale 7 detects the x-direction position x _t of the stage 6, and outputs the position x _t to the controller.
The processing tool 8 is a tool (such as an end mill) that cuts the workpiece W fixed to the stage 6. Note that the cutting force of the workpiece W by the processing tool 8 is expressed as F _cut .

In such a cutting apparatus 1, the stage position x _m calculated from the current Ia (reference value) of the motor 2, the position x _{t of the} stage 6, and the rotation angle of the motor 2 is acquired as internal information.
The cutting force F _cut can be estimated by solving the equation of motion using the internal information.

FIG. 2 is a schematic diagram showing the cutting apparatus 1 shown in FIG. 1 as a two-inertia model.
In FIG. 2, the parameters of the cutting apparatus 1 are the converted mass Mr calculated from the total moment of inertia of the motor 2, the coupling 3, and the ball screw 4, the total mass Mt of the stage 6 and the workpiece W, and the damping coefficient of the motor 2. Cr, damping coefficient Ck of damping component (dashpot) existing between rotating system and translation system, damping coefficient Ct of translation system, torque constant Kt of motor 2, spring existing between rotating system and translation system It is assumed that the component stiffness Kr and the conversion coefficient R between the rotation system and the translation system are represented.
At this time, an equation of motion based on a coordinate system in a general three-dimensional space can be expressed as in equation (1).

なお、（１）式におけるａ_ｍはモータ２の換算加速度、ａ_ｔはステージ６の加速度、ｖ_ｍはモータ２の換算速度、ｖ_ｔはステージ６の速度であり、これらはモータ２の換算移動量ｘ_ｍ及びステージ６の位置ｘ_ｔを一階または二階微分することで得ることができる。
（１）式は、一般化すると以下のように記載できる。
［Ｍ］｛ａ｝＋［Ｃ］｛ｖ｝＋［Ｋ］｛ｘ｝＝｛Ｆ｝ （１−１）
なお、（１−１）式におけるＭ、ａ、Ｃ、ｖ、Ｋ、ｘ、Ｆは、それぞれ一般的な３次元空間における質量、加速度、減衰係数、速度、バネ定数、位置、力のマトリクスを表している。

Incidentally, _{a m} in (1) is the speed of translation speed, _{v t} is the stage 6 Conversion acceleration, _{a t} is the acceleration of the stage 6, _{v m} is the motor 2 of the motor 2, which are converted movement of the motor 2 the amount x _m and the position x _t of the stage 6 can be obtained by differentiating the first floor or the second floor.
When generalized, the formula (1) can be described as follows.
[M] {a} + [C] {v} + [K] {x} = {F} (1-1)
Note that M, a, C, v, K, x, and F in the formula (1-1) are a matrix of mass, acceleration, damping coefficient, velocity, spring constant, position, and force, respectively, in a general three-dimensional space. Represents.

In equation (1), as can be seen by referring to the coefficient matrix of the second term (speed term) and the third term (position term), the off-diagonal term is -Ck or -Kr.
When the expression (1) is expanded, the terms in the first row of each coefficient matrix mainly constitute equations relating to the rotation system, and the terms in the second row of each coefficient matrix mainly constitute equations relating to the translation system.
Here, in Equation (1), the off-diagonal term in the coefficient matrix of the second term and the third term is -Ck or -Kr. As a result, the motion of the motor 2 affects the equations relating to the translation system.

That is, in the equation of motion based on the coordinate system of a general three-dimensional space, the equation relating to the rotation system and the equation relating to the translation system are not independent, and are affected by the interaction between the machine elements, so that the state of the device is increased. It is difficult to estimate with accuracy.
Therefore, in the present invention, a specific coordinate system (mode space) is defined such that the off-diagonal terms of the coefficient matrix of the second term and the third term in equation (1) are zero.
Hereinafter, the conversion from the equation of motion in a general three-dimensional space to the mode space is appropriately referred to as “mode conversion”.

FIG. 3 is a schematic diagram showing the concept of mode conversion in the present invention.
As shown in FIG. 3, in the present invention, the coordinates in the mode space and the coordinates in the three-dimensional space are converted by the mode matrix [φ]. When the position coordinates in the mode space are expressed as a coordinate vector {x _mod } and the coordinates in a general three-dimensional section are expressed as a vector {x}, the mode conversion formula is
{X} = [φ] {x _mod } (2)
Can be expressed as
In the equation (2), the mode matrix [φ] is a matrix in which the element in the second row and the second column is −1 / α, and the other elements are 1. Note that α = Mt / Mr (inertia ratio).

The coordinate vector {x _modal } of the mode space transformed by the mode matrix is
{X _modal } = {x _rigid , x _vib } (3)
, X _rigid represents a _rigid body mode displacement, and x _vib represents a vibration mode displacement.
From the relationship of the expression (2), the rigid body mode displacement and the vibration mode displacement x _rigid , x _vib are the rotation system position (stage position calculated from the rotation angle of the motor 2) x _m and the translation system position (stage). can be obtained from the 6 position) x _t easy.
At this time, the two-inertia model shown in FIG. 2 is converted into two independent modes represented as the rigid body mode and the vibration mode in FIG.
That is, in the rigid body mode, an equation for obtaining the cutting force F _rigid in the rigid body mode can be described using the _rigid body mode displacement x _rigid and the damping coefficient C _rigid as internal information.
Similarly, in the vibration mode, an equation for obtaining the cutting force F _vib in the rigid body mode can be described using the vibration mode displacement x _vib , the damping coefficient C _vib and the spring constant K _vib as internal information.

  Specifically, the equation (4) is obtained by applying the mode conversion equation (2) to the equation of motion (1) and multiplying the transpose matrix of the mode matrix [φ] from the left. .

なお、（４）式において、ｖ_{ｒｉｇｉｄ}は剛体モード速度、ａ_{ｒｉｇｉｄ}は剛体モード加速度、ｖ_ｖｉｂは振動モード加速度、ａ_ｖｉｂは振動モード加速度を表している。
（４）式は、一般化すると以下のように記載できる。
［Ｍ_{ｍｏｄａｌ}］｛ａ_{ｍｏｄａｌ}｝＋［Ｃ_{ｍｏｄａｌ}］｛ｖ_{ｍｏｄａｌ}｝＋［Ｋ_{ｍｏｄａｌ}］｛ｘ_{ｍｏｄａｌ}｝＝｛Ｆ_{ｍｏｄａｌ}｝ （４−１）
なお、（４−１）式におけるＭ_{ｍｏｄａｌ}、ａ_{ｍｏｄａｌ}、Ｃ_{ｍｏｄａｌ}、ｖ_{ｍｏｄａｌ}、Ｋ_{ｍｏｄａｌ}、ｘ_{ｍｏｄａｌ}、Ｆ_{ｍｏｄａｌ}は、それぞれモード空間における質量、加速度、減衰係数、速度、バネ定数、位置、力のマトリクスを表している。
さらに、（４）式を展開して整理すると、（５）式が得られる。

In Equation (4), v _rigid represents a rigid body mode velocity, a _rigid represents a _rigid body mode acceleration, v _vib represents a vibration mode acceleration, and a _vib represents a vibration mode acceleration.
When generalized, the equation (4) can be described as follows.
[M _modal ] {a _modal } + [C _modal ] {v _modal } + [K _modal ] {x _modal } = {F _modal } (4-1)
M _modal , a _modal , C _modal , v _modal , K _modal , x _modal , F _modal in equation (4-1) are the mass, acceleration, damping coefficient, velocity, spring constant, position, force in the mode space, respectively. Represents the matrix.
Furthermore, when formula (4) is expanded and arranged, formula (5) is obtained.

なお、（４）式から（５）式に整理する際に、比例粘性減衰系であることを仮定し、減衰項について、（減衰係数）＝Ａ×（質量）＋Ｂ×（バネ定数）といった簡略化を行っている（Ａ，Ｂは係数）。ただし、減衰項のモデル化方法は比例粘性減衰のみに限定されず、他の手法で簡略化することもできる。

It should be noted that when rearranging from equation (4) to equation (5), it is assumed that the system is a proportional viscous damping system, and the attenuation term is simplified as (attenuation coefficient) = A × (mass) + B × (spring constant). (A and B are coefficients). However, the method of modeling the attenuation term is not limited to proportional viscosity attenuation, and can be simplified by other methods.

In equation (5), the equation consisting of the first row of each coefficient matrix represents the equation of motion in the rigid body mode, and the equation consisting of the second row of each coefficient matrix represents the equation of motion in the vibration mode.
Referring to equation (5), the off-diagonal term of each coefficient matrix is zero, and the equation of motion in the rigid body mode and the equation of motion in the vibration mode are independent of each other.
Therefore, so that the determined according to the equation (5), rigid body modes and motion of the vibration modes for cutting force _{F cut (x rigid, v rigid} , a rigid, x vib, v vib, a vib) to independently.

That is, by performing the mode conversion of the present invention, it is possible to assume a rigid body mode and a vibration mode that can be regarded as independent movements from the two-inertia model of the cutting apparatus 1, and an equation of motion in either mode is obtained. By solving, the state (cutting force F _Cut etc.) of the cutting apparatus 1 can be estimated easily and with high accuracy.

Equation (6) shows the result (cutting force estimation equation) of the rigid body mode equation of equation (5) solved for the cutting force F _cut .

Moreover, (7) Formula has shown the result (cutting force estimation formula) which solved the motion equation of the vibration mode in (5) Formula about cutting force _Fcut .

Referring to the equations (6) and (7), the cutting force F _cut can be estimated from the internal information of the cutting apparatus 1.
In particular, in the equation (7), when the inertia ratio α is smaller than 1, the estimation formula is obtained by reducing the ratio of the current of the motor 2 that is greatly affected by the static frictional force. In addition, the cutting force including the orthogonal direction can be estimated with high accuracy.
Also, by integrating the cutting force / position / speed obtained in the vibration mode and the power factor theory in the electric circuit including the controller, the phase change between the processing force-position and the processing force-speed can be monitored. . Therefore, chatter vibration, which is a kind of abnormal machining, can be detected. Further, by monitoring the current phase difference in the electric circuit, it is possible to set a unique threshold value that is low in calculation load and independent of processing conditions.

[First Embodiment]
Next, an embodiment of the cutting apparatus 1 to which the present invention is applied will be described.
[Constitution]
FIG. 4 is a schematic diagram showing a configuration of the cutting apparatus 1 according to one embodiment of the present invention.
As shown in FIG. 4, the cutting apparatus 1 includes a motor 2, an encoder 2A, a coupling 3, a ball screw 4, a bearing 5, a stage 6, a linear scale 7, a processing tool 8, and a servo. An amplifier 9 and a controller 10 are provided.
Among these, the configurations of the motor 2, the encoder 2A, the coupling 3, the ball screw 4, the bearing 5, the stage 6, the linear scale 7 and the processing tool 8 are the same as those shown in FIG.

The servo amplifier 9 controls the magnitude of torque output from the motor 2 by inputting a current Ia corresponding to the command value Ic from the controller 10 to the motor 2 for driving the stage 6.
The controller 10 includes a control device such as a PC (Personal Computer) or a PLC (Programmable Logic Controller). The controller 10 executes position control of the stage 6 through the servo amplifier 9 by inputting the command value Ic to the servo amplifier 9. Moreover, the controller 10 estimates the cutting force by the processing tool 8 as the state of the cutting apparatus 1 by executing a cutting force estimation process described later.

FIG. 5 is a block diagram illustrating a hardware configuration of the controller 10.
The controller 10 includes a CPU (Central Processing Unit) 31, a ROM (Read Only Memory) 32, a RAM (Random Access Memory) 33, a bus 34, an input / output interface 35, an input unit 36, an output unit 37, A storage unit 38, a communication unit 39, and a drive 40.

The CPU 31 executes various processes according to a program recorded in the ROM 32 or a program loaded from the storage unit 38 to the RAM 33.
The RAM 33 appropriately stores data necessary for the CPU 31 to execute various processes.

  The CPU 31, ROM 32, and RAM 33 are connected to each other via a bus 34. An input / output interface 35 is also connected to the bus 34. An input unit 36, an output unit 37, a storage unit 38, a communication unit 39, and a drive 40 are connected to the input / output interface 35.

The input unit 36 includes a keyboard, a mouse, and the like, and inputs various types of information according to user instruction operations.
The output unit 37 includes a display, a speaker, and the like, and outputs an image and sound.
The storage unit 38 is configured with a hard disk or the like, and stores data of various types of information.
The communication unit 39 controls communication with other terminals (not shown) via the network, outputs a command value Ic to the servo amplifier 9, and sends feedback information to the encoder 2A, the linear scale 7 or The communication for inputting from the servo amplifier 9 is controlled.

  A removable medium 41 composed of a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, or the like is appropriately attached to the drive 40. The program read from the removable medium 41 by the drive 40 is installed in the storage unit 38 as necessary. The removable medium 41 can also store various data stored in the storage unit 38 in the same manner as the storage unit 38.

[Functional configuration]
FIG. 6 is a functional block diagram showing a functional configuration of the controller 10 of the cutting apparatus 1.
As shown in FIG. 6, when the controller 10 operates, in the CPU 31, an information acquisition unit 51, a state estimation unit 52, a process identification unit 53, and a motor drive control unit 54 function.
Information acquiring unit 51 acquires information representing the stage position x _m as calculated from the rotation angle of the motor 2 from the encoder 2A. The information acquisition unit 51 acquires information from the linear scale 7 represents the position x _t of the stage 6.
State estimation unit 52, information representing the position x _m of the motor 2 acquired by the information acquisition unit 51, the input information and the motor drive control unit 54 represents the position x _t of the stage 6 to the motor 2 via a servo amplifier 9 The cutting force by the processing tool 8 is estimated with reference to the current Ia. At this time, the state estimation unit 52 estimates the cutting force by the processing tool 8 in accordance with the cutting force estimation formula shown in Formula (7).
Based on the cutting force by the processing tool 8 estimated by the state estimation unit 52, the stage position x _m calculated from the rotation angle of the motor 2, and the position x _{t of the} stage 6, the process identification unit 53 Perform sensorless process monitoring to detect tool abnormalities such as wear, breakage and breakage.
The motor drive control unit 54 calculates a torque to be generated by the motor 2 based on the cutting force by the processing tool 8 estimated by the state estimation unit 52 and outputs a command value Ic indicating the calculated torque to the servo amplifier 9. To do.

[Operation]
Next, the operation of the cutting apparatus 1 will be described.
FIG. 7 is a flowchart showing the flow of the cutting force estimation process executed by the controller 10 of the cutting apparatus 1.
The cutting force estimation process is executed at the time of cutting in the cutting apparatus 1.
In step S1, the information acquisition unit 51 acquires information representing the stage position (converted movement amount) x _m calculated from the rotation angle of the motor 2 from the encoder 2A, and the position x _{t of the} stage 6 from the linear scale 7. Get information representing.

In step S2, the state estimation unit 52, a stage position calculated from the rotation angle of the motor 2 acquired by the information acquisition unit 51 (in terms of movement amount) information indicating the x _m, and the information representing the position x _t of the stage 6 The motor drive control unit 54 refers to the current Ia input to the motor 2 via the servo amplifier 9.
In step S3, the state estimation unit 52, the information acquisition unit information that represents the stage position x _m as calculated from the rotation angle of the motor 2 obtained by 51, the information and the motor drive control unit 54 represents the position x _t of the stage 6 Based on the current Ia input to the motor 2 via the servo amplifier 9, the cutting force by the processing tool 8 is estimated according to the cutting force estimation formula shown in the formula (7).
In step S4, the process identification unit 53 executes the estimated cutting force, on the basis of the position x _t of the stage position x _m and the stage 6 is calculated from the rotation angle of the motor 2, the sensor-less process monitoring to detect the tool abnormality To do.
In step S <b> 5, the motor drive control unit 54 calculates the torque to be generated by the motor 2 based on the cutting force by the processing tool 8 estimated by the state estimation unit 52.

It should be noted that the machining process is controlled by utilizing the estimation result of the cutting force for controlling not only the rotation axis of the motor 2 but also a different axis (feed axis other than the motor 2 or the main axis on which the processing tool 8 is installed). It is good. For example, it is possible to estimate the cutting force of the rotating shaft (feed shaft) of the motor 2 and vary the torque and the rotational speed of the main shaft on which the processing tool 8 is installed accordingly. Also, a method of simultaneously controlling the speed and torque of multiple axes from the estimated cutting force of one feed axis (single axis information-multi-axis control), and control of multiple axes from the estimated results of cutting force of multiple feed axes It is good also as performing the method (multi-axis information-multi-axis control) etc. to perform.
In step S <b> 6, the motor drive control unit 54 outputs a command value Ic indicating the calculated torque to the servo amplifier 9.
After step S6, the cutting force estimation process ends.

By performing such processing, the cutting device 1 estimates the cutting force from the internal information based on the equation (7).
Since the equation (7) is an estimation equation in which the ratio of the current of the motor 2 that is greatly affected by the static friction force is reduced when the inertia ratio α is smaller than 1, the feed direction of the workpiece W with respect to the processing tool 8 is calculated. In addition, the cutting force including the orthogonal direction can be estimated with high accuracy.
Therefore, according to the cutting apparatus 1 which concerns on this embodiment, the state of the actuator which makes force act on a target object can be estimated more accurately.

[effect]
8A to 8C are diagrams showing an example of the estimation result of the cutting force at the time of side machining by the end mill, FIG. 8A is the estimation result by the vibration mode, and FIG. FIG. 8C is a diagram showing an estimation result based on the rigid body mode (prior art) based on the motor current information. The broken lines in FIGS. 8A to 8C indicate actual measurement values measured using a force sensor. FIG. 8 shows an example of an estimation result in a machining mode in which the cutting amount in the radial direction is 1.5 [mm] and the depth in the axial direction is 0.3 [mm].

As shown in FIG. 8A, in the estimation result by the vibration mode using the equation (7), the cutting force close to the actual measurement value can be estimated with high accuracy both during the end mill cutting and idling. It is possible.
On the other hand, as shown in FIG. 8 (B), in the estimation method that relies heavily on the current information of the motor as the prior art, the estimation error with respect to the actual measurement value is large.

  In addition, in the estimation result by the rigid body mode shown in FIG. 8C (estimation result using the equation (6)), an estimation error is slightly large in the idling region, but the conventional error shown in FIG. Compared with the method, it is possible to estimate the cutting force close to the actual measurement value with relatively high accuracy.

Further, in the estimation of the cutting force by the vibration mode, it is possible to estimate the cutting force with higher accuracy even when the processing modes of the end mill are different.
FIG. 9A and FIG. 9B are diagrams showing an example of the estimation result of the cutting force when the cutting amount is changed, and FIG. 9A is a groove process with a large cutting amount (cutting amount 6). 0.0 mm)), FIG. 9B is a diagram showing an estimation result in the case of side machining with a small cutting amount (cutting amount 0.5 [mm]).

As shown in FIGS. 9A and 9B, when the cutting depth is different, the cutting force shows a waveform with different characteristics, but the estimation result by the vibration mode is the same as the estimation result shown in FIG. Similarly, it is possible to estimate the cutting force with high accuracy with respect to the actually measured value. On the other hand, in the estimation method that relies heavily on the current information of the motor, which is the prior art, both the waveforms in FIG. 9A and FIG. Is getting bigger.
Thus, according to the present invention, it is possible to estimate the state of the actuator that applies force to the object with higher accuracy.

[Modification 1]
In the above-described embodiment, the case where the present invention is applied to an apparatus of a two-inertia model has been described as an example. However, the present invention also applies a mode conversion to the state in the case of a three-inertia model or more. Estimation can be performed.
That is, by adding a position sensor, an angle sensor, or the like, the system can be expanded to a multi-inertia system, and a machining force can be estimated in each mode space (a rigid body mode space and a plurality of vibration mode spaces).

FIG. 10 is a schematic diagram showing the concept of mode conversion of the three inertia model.
As shown in FIG. 10, when mode conversion is performed on a three-inertia model device, the order of the vibration mode increases second-order with respect to the two-inertia model. That is, it can be decomposed into a rigid body mode and primary and secondary vibration modes.
Also in this case, each mode can be handled independently, and the state can be estimated with high accuracy by solving the equation of motion in each mode.
That is, the mode conversion of the three-inertia model is also equivalent to the cutting force estimation formula shown in Formula (7) or Formula (6) by converting coordinates and coefficients according to the procedure described above as the basic concept of the present invention. An expression can be derived.
Thus, by adding a position sensor or an angle sensor, the model of the device can be expanded to an n-inertia system, and the state of the device (cutting) including components corresponding to higher-order vibration modes are included. Force, etc.) can be estimated with high accuracy.

Note that the present invention can be appropriately modified and improved within the scope of the effects of the present invention, and is not limited to the above-described embodiment.
That is, the present invention can be applied to various devices (actuators) in which the servo motor and the load are modeled as a multi-inertia resonance system and the displacement or angle of each element can be measured. For example, the present invention can be applied to machine tools that perform cutting (turning, milling, etc.) and plastic working (pressing, friction stir welding, etc.). Further, the present invention can be applied to a rolling mill, a flexible joint of a robot, a flexible arm, a space structure (manipulator or the like), or a heavy machine such as a power shovel. Furthermore, the present invention can also be applied to the case where the processing state is monitored using an external sensor, and the monitoring of the processing state in various processing apparatuses can be simplified. The present invention can also be applied to state estimation such as monitoring of chatter vibration, tool wear, tool loss or collision detection.

  Moreover, in the above-mentioned embodiment, when estimating the state (cutting force etc.) of the cutting apparatus 1, only the estimation result estimated by (7) Formula or (6) Formula is used, or according to conditions. Thus, it is possible to select and use one of them, or to use an estimation result integrated by weighting both.

  Moreover, in the above-described embodiment, the case where the cutting force is estimated as an example of the state of the cutting apparatus 1 has been described, but the present invention is not limited thereto. In other words, in the present invention, various parameters other than the cutting force can be estimated by solving a motion equation in the mode space.

Moreover, it is possible to implement this invention combining the said embodiment and each modification suitably.
The processing in the above-described embodiment can be executed by either hardware or software.
That is, it is only necessary that the cutting apparatus 1 has a function capable of executing the above-described processing, and what functional configuration and hardware configuration are used to realize this function is not limited to the above-described example.
When the above-described processing is executed by software, a program constituting the software is installed on a computer from a network or a storage medium.

  The storage medium for storing the program is configured by a removable medium distributed separately from the apparatus main body, or a storage medium incorporated in the apparatus main body in advance. The removable medium is composed of, for example, a magnetic disk, an optical disk, a magneto-optical disk, or the like. The optical disk is composed of, for example, a CD-ROM (Compact Disk-Read Only Memory), a DVD (Digital Versatile Disk), a Blu-ray Disc (registered trademark), and the like. The magneto-optical disk is configured by an MD (Mini-Disk) or the like. Further, the storage medium incorporated in advance in the apparatus main body is constituted by, for example, a ROM or a hard disk in which a program is stored.

The cutting apparatus 1 configured as described above includes a state estimation unit 52.
The state estimation unit 52 is a space converted from an n-inertia model representing an actuator based on a parameter representing internal information of the cutting device 1 as an actuator, and is configured by two or more modes independent of each other. The state of the actuator is estimated based on the equation of motion in space.
As a result, two or more modes that can be regarded as independent movements can be assumed from the n-inertia model of the actuator, and the state of the actuator can be easily and highly accurately solved by solving the equation of motion in either mode. Can be estimated.
That is, according to the present invention, the state of the actuator that applies a force to the object can be estimated with higher accuracy.

The modes constituting the space converted from the n-inertia model are independent of the first mode in which the state of the actuator is estimated from the center of gravity movement of the mechanical element of the actuator (for example, the rigid body mode) and the first mode. And a second mode (for example, vibration mode) in which the state of the actuator is estimated from the relative motion between the machine elements.
As a result, the state of the actuator can be estimated in accordance with various movements of the actuator.

The state estimation unit 52 estimates the state of the actuator using at least the estimation result based on the equation of motion corresponding to the second mode.
Thereby, the state of the actuator can be estimated with higher accuracy even in a specific state such as a region where the movement of the actuator is restricted by the static frictional force.

The equation of motion in the space constituted by the modes is defined by applying a transformation matrix having zero off-diagonal terms in the coefficient matrix of the equation of motion to a predetermined equation of motion in the n-inertia model.
Thereby, since the equation of motion of the space constituted by the modes can be solved more easily, the state of the actuator can be easily estimated.

The transformation matrix is defined to include elements determined by the inertia ratio of the inertial system constituting the n-inertia model.
Thereby, a transformation matrix can be defined based on a clear physical quantity in the n-inertia model.

  1 Cutting device, 2 motor, 2A encoder, 3 coupling, 4 ball screw, 5 bearing, 6 stage, 7 linear scale, 8 processing tool, 9 servo amplifier, 10 controller, 31 CPU, 32 ROM, 33 RAM, 34 Bus, 35 Input / output interface, 36 Input section, 37 Output section, 38 Storage section, 39 Communication section, 40 Drive, 41 Removable media, 51 Information acquisition section, 52 State estimation section, 53 Process identification section, 54 Motor drive control section , W work

Claims (7)

A state estimation device that estimates the state of an actuator that applies force to an object,
Based on an equation of motion in a space converted from an n-inertia model representing the actuator based on a parameter representing internal information of the actuator, the space being constituted by two or more independent modes A state estimation device comprising: state estimation means for estimating the state of   The mode constituting the space transformed from the n-inertia model is independent of the first mode and the first mode in which the state of the actuator is estimated from the center of gravity movement of the mechanical element of the actuator. The state estimation apparatus according to claim 1, further comprising: a second mode in which a state of the actuator is estimated from a relative motion between the mechanical elements.   The state estimation device according to claim 2, wherein the state estimation means estimates the state of the actuator using at least an estimation result based on an equation of motion corresponding to the second mode.   The equation of motion in the space constituted by the modes is defined by applying a transformation matrix having zero off-diagonal terms in the coefficient matrix of the equation of motion to a predetermined equation of motion in the n-inertia model. The state estimation apparatus according to any one of claims 1 to 3.   The state estimation apparatus according to claim 4, wherein the transformation matrix is defined including an element determined by an inertia ratio of an inertial system constituting the n-inertia model. A state estimation method executed by a state estimation device that estimates a state of an actuator that applies a force to an object,
Based on an equation of motion in a space converted from an n-inertia model representing the actuator based on a parameter representing internal information of the actuator, the space being constituted by two or more independent modes The state estimation method characterized by including the state estimation step which estimates the state of this. In a computer constituting a state estimation device that estimates the state of an actuator that applies force to an object,
Based on an equation of motion in a space converted from an n-inertia model representing the actuator based on a parameter representing internal information of the actuator, the space being constituted by two or more independent modes A program characterized by realizing a state estimation function for estimating a state of a computer.

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