Machine tool, control device for machine tool, and machine tool control method

Abstract

To carry out movement control of a moving body with high accuracy.SOLUTION: A machine tool comprises a feed-drive unit for moving a moving body on a machine tool, a feedback control section for feedback-controlling the feed-drive unit depending on a status variable, a friction compensating section that previously adds a friction compensating value obtained from measurement data on rolling friction or a friction compensating value calculated using a rolling friction model to a command value to be inputted to the feed-drive unit, in order to compensate for rolling friction occurring at the feed-drive unit, and an inverse-response reducing section that reduces an inverse response caused by an addition of the friction compensating value by utilization of a status variable at the feedback control section.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a machine tool, a control device for a machine tool, and a machine tool control method. [Background technology]

[0002] In the technical field described above, Patent Document 1 discloses a technique for controlling the movement of an object by estimating the frictional force. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 5560068 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, the techniques described in the above-mentioned literature sometimes resulted in a reverse response due to friction compensation, leading to low accuracy in object movement.

[0005] The object of the present invention is to provide a technology that solves the above-mentioned problems. [Means for solving the problem]

[0006] To achieve the above objective, the machine tool according to the present invention is A feed drive unit for moving a moving body in a machine tool, A feedback control unit for feedback-controlling the feed drive unit according to a state variable, In order to compensate for the rolling friction generated in the feed drive unit, a friction compensation unit is provided that pre-adds a friction compensation value obtained from rolling friction measurement data, or a friction compensation value calculated using a rolling friction model, to the command value input to the feed drive unit. A reverse response reduction unit that reduces the reverse response caused by the addition of the friction compensation value using the state variables, A machine tool equipped with, The aforementioned inverse response reduction unit is In order to reduce the reverse response caused by the addition of the friction compensation value, the machine tool adds an additional input value equivalent to the reset of the state variable to the command value at the timing when the tracking error in the quadrant projection direction by the feed drive unit is maximum, after the velocity of the moving body is reversed. To achieve the above objective, other machine tools according to the present invention are: A feed drive unit for moving a moving body in a machine tool, A feedback control unit for feedback-controlling the feed drive unit according to a state variable, In order to compensate for the rolling friction generated in the feed drive unit, a friction compensation unit is provided that pre-adds a friction compensation value obtained from rolling friction measurement data, or a friction compensation value calculated using a rolling friction model, to the command value input to the feed drive unit. A reverse response reduction unit that reduces the reverse response caused by the addition of the friction compensation value using the state variables, A machine tool equipped with, The aforementioned inverse response reduction unit is In order to reduce the reverse response caused by the addition of the friction compensation value, the machine tool performs initial value compensation by resetting the state variable in real time at the timing when the error in the quadrant projection direction by the feed drive unit is maximum after the velocity of the moving body is reversed. To achieve the above objective, the control device for machine tools according to the present invention is A feedback control unit for feedback-controlling a feed drive unit for moving a moving body in a machine tool according to state variables, In order to compensate for the rolling friction generated in the feed drive unit, a friction compensation unit is provided that pre-adds a friction compensation value obtained from rolling friction measurement data, or a friction compensation value calculated using a rolling friction model, to the command value input to the feed drive unit. A reverse response reduction unit that reduces the reverse response caused by the addition of the friction compensation value using the state variables, A control device for a machine tool, comprising: The reverse response reduction unit is configured to In order to reduce the reverse response generated by the addition of the friction compensation value, an equivalent input value to the reset of the state variable is added to the command value at the timing when the following error in the quadrant protrusion direction by the feed drive unit becomes maximum after the speed reversal of the moving body. This is a control device for a machine tool. To achieve the above object, another control device for a machine tool according to the present invention is A feed drive unit for moving a moving body in a machine tool, A feedback control unit for feedback - controlling the feed drive unit according to a state variable, In order to compensate for the rolling friction generated in the feed drive unit, a friction compensation value obtained from measurement data of rolling friction or a friction compensation value calculated using a rolling friction model is added in advance to the command value input to the feed drive unit. This is a friction compensation unit, An inverse response reduction unit that uses the state variable to reduce the inverse response generated by the addition of the friction compensation value, A control device for a machine tool including The inverse response reduction unit is configured to In order to reduce the inverse response generated by the addition of the friction compensation value, initial value compensation is performed to reset the state variable in real - time at the timing when the error in the quadrant protrusion direction by the feed drive unit becomes maximum after the speed reversal of the moving body. This is a control device for a machine tool. To achieve the above object, a machine tool control method according to the present invention is A feedback control step for feedback - controlling a feed drive unit for moving a moving body in a machine tool according to a state variable, A friction compensation step for adding in advance a friction compensation value obtained from measurement data of rolling friction or a friction compensation value calculated using a rolling friction model to the command value input to the feed drive unit in order to compensate for the rolling friction generated in the feed drive unit, An inverse response reduction step that uses the state variable to reduce the inverse response generated by the addition of the friction compensation value, A machine tool control method including In the aforementioned inverse response reduction step, In order to reduce the reverse response caused by the addition of the friction compensation value, this machine tool control method adds an additional input value equivalent to the reset of the state variable to the command value at the timing when the tracking error in the quadrant projection direction by the feed drive unit is maximum, after the velocity of the moving body is reversed. To achieve the above objective, another machine tool control method according to the present invention is: A feedback control step for feedback-controlling a feed drive unit for moving a moving body in a machine tool according to a state variable, In order to compensate for the rolling friction generated in the feed drive unit, a friction compensation step is performed in which a friction compensation value obtained from rolling friction measurement data, or a friction compensation value calculated using a rolling friction model, is added in advance to the command value input to the feed drive unit. A reverse response reduction step that reduces the reverse response caused by the addition of the friction compensation value using the state variables, A machine tool control method including, In the aforementioned inverse response reduction step, In order to reduce the reverse response caused by the addition of the friction compensation value, this machine tool control method performs initial value compensation by resetting the state variable in real time at the timing when the error in the quadrant projection direction by the feed drive unit is maximum after the velocity of the moving body is reversed. [Effects of the Invention]

[0007] According to the present invention, the movement of a moving object can be controlled with high precision. [Brief explanation of the drawing]

[0008] [Figure 1] This is a block diagram showing the configuration of a machine tool according to the first embodiment. [Figure 2] Block diagram showing the hardware configuration of a machine tool according to the second embodiment. [Figure 3] This is a block diagram showing the functional configuration of a machine tool according to the second embodiment. [Figure 4] This is a diagram explaining the inverse quadrant projection. [Figure 5] This is a block diagram showing the control system of a machine tool according to the second embodiment. [Figure 6] This is a block diagram showing the control system of a machine tool according to the second embodiment. [Figure 7] This is a block diagram showing the functional configuration of a machine tool according to the third embodiment. [Figure 8] This is a block diagram showing the control system of a machine tool according to the third embodiment. [Figure 9] This is a block diagram showing the control system of a machine tool according to the third embodiment. [Figure 10] This figure shows a method for calculating additional input values ​​in a machine tool according to the third embodiment. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described in detail below with reference to the drawings. However, the components described in the following embodiments are merely illustrative and are not intended to limit the technical scope of the present invention to them alone.

[0010] In this specification, "reverse response" refers to a tracking error (reverse quadrant projection) that is in the opposite direction to the tracking error (reverse quadrant projection) that occurs when the velocity is reversed.

[0011] [First Embodiment] A first embodiment of the present invention, an object moving device 100, will be described with reference to Figure 1. The object moving device 100 is incorporated into a machine tool and is a device for moving a workpiece placed on a stage.

[0012] As shown in Figure 1, the machine tool 100 includes a feed drive unit 101, a feedback control unit 102, a friction compensation unit 103, and a reverse response reduction unit 104.

[0013] The feed drive unit 101 moves the movable body 120 in the machine tool 100. The feedback control unit 102 provides feedback control to the feed drive unit 101 according to an internal state variable 121.

[0014] The friction compensation unit 103 pre-adds to the command value 105 to the feed drive unit 101 a friction compensation value 131 obtained from measurement data of rolling friction, or a friction compensation value 131 calculated using a rolling friction model, in order to compensate for the rolling friction generated in the feed drive unit 101.

[0015] The inverse response reduction unit 104 uses the state variable 121 of the feedback control unit 102 to reduce the inverse response that occurs when friction compensation values ​​are added.

[0016] According to this embodiment, the above configuration makes it possible to move the moving object with higher precision.

[0017] [Second Embodiment] Next, a machine tool 200 according to a second embodiment of the present invention will be described using Figures 2 and subsequent figures. Figure 2 is a diagram illustrating the configuration of the machine tool 200 according to this embodiment. The machine tool 200 is equipped with a ball screw 202 to move a stage 201 which acts as a moving body. Such ball screw-driven stages are often used as feed devices in industrial machinery such as machine tools because they have high energy conversion efficiency, low wear, and a long lifespan.

[0018] The ball screw 202 is connected to the motor 204 via the coupling 203 and is supported by the bearing 205. As the ball screw 202 rotates, the nut 206 moves left to right in the figure, causing the stage 201 to move in the X-axis direction while being guided by the linear guide 207. The section from the ball screw 202 to the linear guide 207 is collectively referred to as the feed drive unit. The same applies to Figures 3 and 7.

[0019] The machine tool 200 is equipped with a tool 208 and processes a workpiece 209 fixed to a stage 201. In this process, high-precision drive control of the stage is required to improve processing quality and throughput.

[0020] Figure 3 illustrates the configuration for drive control of the x and y axis ball screw driven stage 201 in the machine tool 200. The stage 201 reciprocates in the x and y axis directions within the movement region 330. The x axis is positioned on top of the y axis. The angles of the drive motors for both the x and y axes are measured by a rotary encoder with a resolution of 20 bits, and the stage position is measured by a linear scale with a resolution of 1 nm. In this embodiment, the input is the current of the drive motor for each axis, and the output is the stage position for each axis, with the aim of controlling the stage position. Here, the x and y axes are controlled independently.

[0021] (Frequency characteristics) Based on the frequency characteristics from the motor current u [A] to the stage position y [m], the controlled object is modeled as a rigid body for each axis, and its transfer function is defined as follows.

[0022] P(s) = R·K T / (Js 2 +Ds)···(1) Here, J is the equivalent inertia considering the stage weight, D is the viscous friction coefficient, R is the ratio of rotation to translation of the ball screw, and KT is the torque constant.

[0023] In a ball screw-driven stage 201 like this, rolling friction leads to a decrease in tracking performance. Rolling friction is generated by the balls 261 between the ball screw 202 and the nut 206, and by the balls within the linear guide 207.

[0024] Graph 350 shows the relationship between the stage position and the rolling friction of the ball screw. The rolling friction depends on the displacement from the velocity reversal point. For example, the stage 201 starts moving from the starting position 351, the velocity reverses at the velocity reversal position 352, and the stage 201 returns to the original starting position 351. In region 353, from the starting position 351 until the stage 201 has moved a predetermined distance, the rolling friction exhibits nonlinear spring characteristics. On the other hand, in region 354, after the stage 201 has moved a predetermined distance from the starting position 351 until the velocity reversal position 352, the rolling friction becomes a constant value as Coulomb friction.

[0025] Furthermore, in region 355 between the reversal at the velocity reversal position 352 and the stage 201 moving a predetermined distance, the rolling friction exhibits nonlinear spring characteristics, and thereafter, in region 356 up to the starting position 351, the rolling friction becomes a constant value.

[0026] Due to this rolling friction, large, spike-like tracking errors called quadrant protrusions occur near the velocity reversal point. In machine tools, these quadrant protrusions can cause excessive cutting and roughening of the workpiece surface. Therefore, machine tool 200 compensates for rolling friction and suppresses quadrant protrusions.

[0027] For compensating rolling friction, model-based and learning-based feedforward friction compensation approaches are more effective than feedback approaches such as disturbance observers.

[0028] Many rolling friction models have been proposed and evaluated to date, including the LuGre model, the generalized Maxwell-slip model, rheology-based models, database friction models, and elastoplastic-based models. Model-based friction compensation approaches precisely measure rolling friction and generate a model through curve fitting. Then, rolling friction is compensated with a control input calculated based on the obtained model. In contrast, learning-based approaches, such as iterative learning control, do not use a rolling friction model, but rather suppress quadrant protrusions by gradually shaping the friction compensation input over multiple movement control cycles.

[0029] To compensate for the rolling friction in this way, the machine tool 200 includes a data acquisition unit 302, a derivation unit 303, and a control unit 306.

[0030] The data acquisition unit 302 acquires command data 321 (displacement data r j ) indicating the displacement of the stage 201 and current data 322 (= f np j+1 ) for driving the motor 204.

[0031] The data acquisition unit 302 detects the speed reversal positions 352 and 351 based on the speed derived from the displacement data r j , and determines whether the stage 201 is in the linear regions 354 and 356 or in the non-linear regions 353 and 355 based on the displacement amounts from the speed reversal positions 351 and 352.

[0032] The derivation unit 303 estimates a linear relational expression 333 (= (f j )) between the base function Ψ(r np j+1 ) based on the displacement data 321 and the current data 322 in the linear regions 354 and 356. The θ p j+1 in the linear relational expression 333 corresponds to the physical characteristics of the stage 201. j )θ j+1 )) from the current data 322 (= f j+1 As described above, according to the feedforward friction compensation, the tracking error can be effectively reduced, but as a result of the friction compensation, an inverse response (inverse quadrant bump) that is a tracking error in the opposite direction to the quadrant bump may occur (Fig. 4). This inverse response leads to overcutting (engaging) etc. in the cutting process of the machine tool. According to the analysis of the inverse response by simulation conducted by the applicant, when the equivalent input-side disturbance generated during the friction compensation is regarded as an impulse disturbance, it was found that the inverse quadrant bump is generated by the impulse disturbance and the integrator of the feedback controller.

[0033]

[0034] ​ In a two-degree-of-freedom control system that performs rolling friction compensation using a friction model, even when there is no modeling error, an inverse quadrant protrusion occurs due to the compensation error of rolling friction between sample points caused by the zero-order hold of the control input and the integrator of the feedback controller C.

[0035] However, integrators are essential for suppressing steady-state errors and disturbances. In fact, in industry, controllers with integrators, such as PID controllers and P-PI controllers, are widely used as feedback controllers.

[0036] Therefore, a control system that satisfies the following requirements (R1)-(R3) is required. (R1) To suppress steady-state errors and steady-state disturbances, a feedback controller has an integrator. (R2) Suppress the inverse quadrant without increasing the size of the quadrant process. (R3) No redesign of the control system is required due to changes in the target trajectory of the stage.

[0037] Therefore, in this embodiment, the control unit 306 uses a conventional PID controller as the feedback control unit 361, and the state variable reset unit 362 achieves the above requirement by resetting the state variables of the PID controller at a certain timing. In other words, the state variable reset unit 362 performs initial value compensation to reset the state variables of the feedback control unit 361.

[0038] The control unit 306 controls the current data 363 for driving the motor 204 in linear regions 354 and 356, and the command value trajectory data r for the next operation. j+1 Basis function Ψ(r j+1 ) and the linear relation 333(=(f p j+1 Ψ(r j )θ j+1 The calculation is performed using ). The control unit 306 also derives current data 364 for driving the motor 204 in the nonlinear regions 353 and 355 using current data 322.

[0039] At this time, the control unit 306 uses a friction model T^rf, as shown in graph 350, to compensate for rolling friction through feedforward control by the friction compensation unit 360. The friction compensation value is calculated based on the friction model and the target position trajectory of the stage.

[0040] The control unit 306 then drives the motor 204 using the calculated current data 363 and the derived current data 364.

[0041] Figure 5 shows a typical two-degree-of-freedom control system that performs rolling friction compensation using a friction model in this embodiment. The controller includes a feedforward controller 501 based on the inverse of the characteristic P from motor current to stage position, a rolling friction compensator 503 using the rolling friction model T^rf, and a feedback controller 502 for suppressing modeling errors. The feedback controller 502 is a PID (Proportional-Integral-Derivative) controller with an integrator to suppress steady-state errors and steady-state disturbances. The controlled object 507 represents the feed drive unit and the stage.

[0042] C(s)=Kp+Ki(1 / s)+Kd(s / (Tfs+1))...(2) Here, Kp is the proportional gain, Ki is the integral gain, Kd is the differential gain, and Tf is the time constant of the pseudo-derivative. All four of these parameters are greater than zero and are designed to stabilize the closed-loop system. The control input is discretized at each control period Ts using a zero-order hold 506. Rolling friction, which depends on the position and velocity of the ball screw drive stage, acts as an input-end disturbance.

[0043] By realizing the controlled object P in this study, shown in equation (1), using a controllable canonical system, the following equation is obtained. d(t) is rolling friction acting as an input end disturbance.

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[0044] Based on assumptions (A1) and (A2), the control system shown in Figure 5 is simplified as shown in Figure 6. Furthermore, based on assumptions (A2) and (A3), disturbances can be ignored at time t = t+ when the state variables of the feedback controller 502 are reset. Therefore, using Figure 5 and the above equation, the closed-loop system G at time t ≥ t+ is expressed by the following equation.

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[0045] From equation (7), the zeros of the initial response of the closed-loop system change depending on the reset value x+c of the state variable of the feedback controller C. (Reset conditions and reset time) According to requirement (R2), in order to prevent the quadrant protrusion from becoming large, a reset must be performed after the time when the error in the direction of the quadrant protrusion is maximum, and before the time when the inverse quadrant protrusion begins. Also, according to requirement (R3), the reset condition must be confirmed in real time. Therefore, in this embodiment, when the timing when the quadrant protrusion is maximum is detected in real time, the state variable of the feedback controller C is reset to xc = xc+.

[0046] To detect the time when the quadrant protrusion is at its maximum, we only need to track the change in the sign of the gradient of the tracking error. That is, if we let the current tracking error be e(iTs) and the tracking error from one sample ago be e((i-1)Ts), and express the difference Δe(iTs) as equation (8) below, then reset the state variable of the feedback controller C when equation (9) is satisfied. Also, to avoid multiple consecutive resets, once a reset has occurred, no further resets will be performed until the stage's target trajectory reverses velocity.

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[0047] In this embodiment, the state variable of the feedback controller 502 is reset when the quadrant protrusion is at its maximum, so ideally, the following equation (12) holds.

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[0048] Furthermore, by comparing the s term and the constant term in equations (15) and (16), the relationship between the two zeros of the initial response of the closed-loop system and t11 and t21 can be obtained as shown in equation (18).

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[0049] Let y(t) be the response of a stable closed-loop system G after the state variables have been reset. If we let τ = t - t + then, by the definition of the Laplace transform, the following equation (20) holds.

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[0050] In other words, let the configuration zeros be zg1 = zg2 = (1 / 3)·pgΣ. At this point, the remaining zero zg3 is also given by equation (17) as zg3 = (1 / 3)·pgΣ. Note that there is some degree of freedom in choosing the imaginary parts of the configuration zeros zg1 and zg2, but here we assume they are real numbers.

[0051] As described above, by resetting the state variables, it is possible to suppress the inverse quadrant protrusion without increasing the quadrant protrusion. This was confirmed by simulation and experiment. Specifically, by resetting the state variables, the feedback input changes in a step-like manner, thereby suppressing the inverse quadrant protrusion.

[0052] [Third Embodiment] Next, a machine tool 700 according to a third embodiment of the present invention will be described with reference to Figure 7. Figure 7 is a diagram illustrating the control system of the machine tool 700 according to this embodiment. Compared to the second embodiment described above, the machine tool 700 according to this embodiment differs in that the control unit 706 has an additional input unit 762 instead of a state variable reset unit 362. The other configurations and operations are the same as in the second embodiment, so the same reference numerals are used for the same configurations and operations and their detailed descriptions are omitted.

[0053] This embodiment is particularly effective when it is not possible to easily reset the state variables of the feedback control unit 361.

[0054] Figure 8 shows a typical two-degree-of-freedom control system that performs rolling friction compensation using the friction model in this embodiment. The additional input value Ua is added to the friction compensation value Ufc by the adder 802.

[0055] The additional input values ​​are used to reassign the zeros of the initial response of the closed-loop system, thereby forming the response of the closed-loop system.

[0056] Here, in order to derive the response of the feedback controller 502 after the additional input, we make the following assumptions (B1)-(B3). (B1) In Figure 8, the feedforward controller 501 ensures the tracking performance to the target trajectory r when there are no modeling errors or disturbances. (B2) In Figure 8, the friction compensation error due to the zero-order hold 506 is considered as an input terminal impulse disturbance applied during velocity reversal. (B3) Additional input is applied after velocity inversion.

[0057] Under the above assumptions, if we simplify the control system shown in Figure 8 as shown in Figure 9, the closed-loop system G after the additional input can be derived as follows.

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[0058] <Timing of additional inputs> The timing of the additional input is the same as the reset timing of the state variable in the second embodiment, being after the time when the quadrant protrusion is at its maximum and before the time when the inverse quadrant protrusion begins. Therefore, in this embodiment, when the time when the quadrant protrusion is at its maximum (equations (8) and (9)) is detected in real time, the additional input value is added. In other words, the additional input unit 762 adds the additional input value to the command data 321 within a predetermined time after the velocity of the moving body 201 is reversed. Specifically, the additional input value is added to the command data 321 at the timing when the tracking error in the direction of the quadrant protrusion by the feed drive units 202 to 207 is at its maximum.

[0059] <Magnitude of additional input value> Furthermore, when determining the magnitude of the additional input value Ua(s), T can be found by setting Yr(s)=Ya(s) in equation (11) of the second embodiment. In this embodiment, the matrix [Ng1(s) ··· Ng4(s)] in equation (11) is a 1 × 4 matrix, and each element is expressed by the following equation.

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[0060] According to the above equation, the response Yr(s) has three zeros -zg1, -zg2, and -zg3 that satisfy the following equation. Ng(s) = (s + zg1)(s + zg2)(s + zg3) Comparing the coefficients in the above equation yields the following equation. zg1 + zg2 + zg3 = pgΣ

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[0061] zg1=zg2=zg3=(pgΣ) / 3···(27) By substituting equation (27) into equation (26), we obtain gains t11 and t21.

[0062] By solving Yr(s)=Ya(s), the additional input value Ua(s) can be expressed by the following formula.

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[0063] Figure 10 shows the calculation formula 1001 and the calculation block diagram 1002 for the additional input value. In this way, the additional input unit 762 adds an additional input value to the command value that is equivalent to resetting the state variable of the feedback control unit 361 in order to reduce the inverse response that occurs when the friction compensation value is added. In other words, the additional input unit 762 calculates an additional input value that makes all the zeros of the initial value response of the feedback control unit 361 equal.

[0064] In this embodiment, a ball screw was used as an example of a feed drive unit, but the present invention is not limited thereto. Furthermore, in the above embodiment, a friction compensation value calculated using a rolling friction model was added to the current value, but the present invention is not limited thereto, and a friction compensation value obtained from rolling friction measurement data may also be added to the current value.

[0065] Furthermore, a control device for a machine tool equipped with a friction compensation unit and a reverse response reduction unit to realize the above-mentioned control in a machine tool is also included in the scope of the present invention.

[0066] [Other embodiments] Although the present invention has been described above with reference to embodiments, the present invention is not limited to the above embodiments. Various modifications to the structure and details of the present invention can be made, as can be understood by those skilled in the art within the technical scope of the present invention. Furthermore, any system or apparatus that combines the separate features included in each embodiment is also within the technical scope of the present invention.

[0067] Furthermore, the present invention may be applied to a system composed of multiple devices or to a single device. Moreover, the present invention is also applicable when an information processing program that realizes the functions of the embodiment is supplied to a system or device and executed by a built-in processor. The technical scope of the present invention includes programs installed on a computer to realize the functions of the present invention on a computer, or a medium storing such a program, a server that downloads such a program, and a processor that executes such a program. In particular, at least a non-transitory computer-readable medium storing a program that causes a computer to execute the processing steps included in the embodiments described above is included in the technical scope of the present invention.

Claims

1. A feed drive unit for moving a moving body in a machine tool, A feedback control unit for feedback-controlling the feed drive unit according to a state variable, In order to compensate for the rolling friction generated in the feed drive unit, a friction compensation unit is provided that pre-adds a friction compensation value obtained from rolling friction measurement data, or a friction compensation value calculated using a rolling friction model, to the command value input to the feed drive unit. A reverse response reduction unit that reduces the reverse response caused by the addition of the friction compensation value using the state variables, A machine tool equipped with, The aforementioned inverse response reduction unit is A machine tool that, in order to reduce the reverse response caused by the addition of the friction compensation value, adds an additional input value equivalent to the reset of the state variable to the command value at the timing when the tracking error in the quadrant projection direction by the feed drive unit is maximum, after the velocity of the moving body is reversed.

2. The aforementioned inverse response reduction unit is The machine tool according to claim 1, which calculates the additional input value such that all zeros of the initial value response of the feedback control unit are equal.

3. A feed drive unit for moving a moving body in a machine tool, A feedback control unit for feedback-controlling the feed drive unit according to a state variable, In order to compensate for the rolling friction generated in the feed drive unit, a friction compensation unit is provided that pre-adds a friction compensation value obtained from rolling friction measurement data, or a friction compensation value calculated using a rolling friction model, to the command value input to the feed drive unit. A reverse response reduction unit that reduces the reverse response caused by the addition of the friction compensation value using the state variables, A machine tool equipped with, The aforementioned inverse response reduction unit is A machine tool that performs initial value compensation in real time to reduce the reverse response caused by the addition of the friction compensation value, by resetting the state variable in real time at the timing when the error in the quadrant projection direction by the feed drive unit is maximum after the velocity of the moving body is reversed.

4. The aforementioned inverse response reduction unit is The machine tool according to claim 3, wherein the state variable is reset so that all zeros of the initial value response of the feedback control unit are equal.

5. A feedback control unit for feedback-controlling a feed drive unit for moving a moving body in a machine tool according to state variables, In order to compensate for the rolling friction generated in the feed drive unit, a friction compensation unit is provided that pre-adds a friction compensation value obtained from rolling friction measurement data, or a friction compensation value calculated using a rolling friction model, to the command value input to the feed drive unit. A reverse response reduction unit that reduces the reverse response caused by the addition of the friction compensation value using the state variables, A control device for a machine tool, comprising: The aforementioned inverse response reduction unit is A control device for a machine tool that, in order to reduce the reverse response caused by the addition of the friction compensation value, adds an additional input value equivalent to the reset of the state variable to the command value at the timing when the tracking error in the quadrant projection direction by the feed drive unit is maximum after the velocity of the moving body is reversed.

6. A feed drive unit for moving a moving body in a machine tool, A feedback control unit for feedback-controlling the feed drive unit according to a state variable, In order to compensate for the rolling friction generated in the feed drive unit, a friction compensation unit is provided that pre-adds a friction compensation value obtained from rolling friction measurement data, or a friction compensation value calculated using a rolling friction model, to the command value input to the feed drive unit. A reverse response reduction unit that reduces the reverse response caused by the addition of the friction compensation value using the state variables, A control device for a machine tool, comprising: The aforementioned inverse response reduction unit is A control device for a machine tool that performs initial value compensation by resetting the state variable in real time at the timing when the error in the quadrant projection direction by the feed drive unit is maximum, after the velocity of the moving body is reversed, in order to reduce the reverse response caused by the addition of the friction compensation value.

7. A feedback control step for feedback-controlling a feed drive unit for moving a moving body in a machine tool according to a state variable, In order to compensate for the rolling friction generated in the feed drive unit, a friction compensation step is performed in which a friction compensation value obtained from rolling friction measurement data, or a friction compensation value calculated using a rolling friction model, is added in advance to the command value input to the feed drive unit. A reverse response reduction step that reduces the reverse response caused by the addition of the friction compensation value using the state variables, A machine tool control method including, In the aforementioned inverse response reduction step, A machine tool control method that, in order to reduce the reverse response caused by the addition of the friction compensation value, adds an additional input value equivalent to the reset of the state variable to the command value at the timing when the tracking error in the quadrant projection direction by the feed drive unit is maximum after the velocity of the moving body is reversed.

8. A feedback control step for feedback-controlling a feed drive unit for moving a moving body in a machine tool according to a state variable, In order to compensate for the rolling friction generated in the feed drive unit, a friction compensation step is performed in which a friction compensation value obtained from rolling friction measurement data, or a friction compensation value calculated using a rolling friction model, is added in advance to the command value input to the feed drive unit. A reverse response reduction step that reduces the reverse response caused by the addition of the friction compensation value using the state variables, A machine tool control method including, In the aforementioned inverse response reduction step, A machine tool control method that performs initial value compensation in which, in order to reduce the reverse response caused by the addition of the friction compensation value, the state variable is reset in real time at the timing when the error in the quadrant projection direction by the feed drive unit is maximum after the velocity of the moving body is reversed.

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