Torque control device, torque control method, and driving device

Abstract

To provide a torque control device, a torque control method, and a driving device that can drive a plurality of motors with respective optimal control parameters.SOLUTION: A torque control device of the present invention comprises: a calculation unit that, on the basis of output voltages output respectively to a plurality of motors that drive and support one unit, calculates the mass of the unit supported by the motors; and a setting unit that sets an optimal gain of the motors on the basis of a mass comparison between the calculated mass and an ideal value.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a torque control device, a torque control method, and a drive device. [Background technology]

[0002] Patent Document 1 discloses a technology for raising and lowering a single unit using two motors, one in the front and one in the back, and controlling its position to keep it level. Patent Document 2 also discloses a technology for an image forming device that changes the control method of the carriage motor depending on the amount of ink in an ink tank, thereby controlling the carriage to an appropriate position to improve print quality and preventing difficulties in carriage drive control due to an overcurrent request. Summary of the Invention [Problem to be solved by the invention]

[0003] However, with the above technology, for example, in the print head array of an image forming device, if there is a change over time in the amount of ink and the shape of the harness of the moving parts, a change over time in the mechanical load, or a change from the assumption of the weight supported by the front and rear motors due to instrumental error, the control parameters of each motor for the weight will not be optimal, and the control response will change between the front and rear motors.

[0004] The present invention has been made in view of the above, and aims to provide a torque control device, a torque control method, and a drive device that can drive a plurality of motors with optimal control parameters. [Means for solving the problem]

[0005] In order to solve the above-mentioned problems and achieve the object, the present invention comprises a calculation unit that calculates the mass of a unit supported by a plurality of motors that drive and support one unit based on the output voltage output to each of the motors, and a setting unit that sets an optimal gain for the motor based on a mass comparison between the calculated mass and an ideal value. [Effects of the Invention]

[0006] According to the present invention, it is possible to drive a plurality of motors with optimal control parameters. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a line head printing machine to which a torque control device according to a first embodiment is applied. [Figure 2] FIG. 2 is a diagram illustrating an example of the configuration of a registration / imaging unit of a line head printing machine according to the first embodiment. [Figure 3] FIG. 3 is a diagram illustrating an example of the configuration of a print head array of a line head printer according to the first embodiment. [Figure 4] FIG. 4 is a block diagram illustrating an example of the configuration of a motor controller of a line head printing machine according to the first embodiment. [Figure 5] FIG. 5 is a diagram illustrating an example of an electrical processing block in a motor controller of a line head printing press according to the first embodiment. [Figure 6] FIG. 6 is a flowchart showing an example of the flow of a motor control process in the line head printing machine according to the first embodiment. [Figure 7] FIG. 7 is a flowchart showing an example of the flow of a motor control process in a line head printing machine according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a torque control device, a torque control method, and a drive device will be described in detail with reference to the accompanying drawings.

[0009] (First embodiment) Fig. 1 is a diagram showing an example of the configuration of a line head printing machine to which a torque control device according to the first embodiment is applied. As shown in Fig. 1, the line head printing machine according to the present embodiment has a registration / imaging unit 1, a pre-coating unit 2, a paper feeding unit 3, a drying / cooling unit 4, a reversing unit 5, and a paper discharge unit 6.

[0010] The paper feed unit 3 feeds and transports two sheets of paper at a time. The pre-coating unit 2 applies an undercoat liquid to the paper beforehand, since ink does not adhere well to some types of paper. The registration and imaging unit 1 detects and corrects the registration and skew of the paper. The registration and imaging unit 1 then transfers the paper from the cylinder (upstream) to the imaging drum 15 (see Figure 2) using a gripper (paper transport claw) 13 (see Figure 2). The registration and imaging unit 1 also prints using print heads 17a to 17d (see Figure 2), such as line heads, while adsorbing the paper to the imaging drum 15. In the following explanation, when there is no need to distinguish between the print heads 17a to 17d, they will be referred to as print head 17.

[0011] The drying and cooling unit 4 dries the water content of the ink. The drying and cooling unit 4 cools the paper as it can get very hot depending on the paper. The reversing unit 5 performs a switchback reversal when printing on the back side, and transports the paper in the direction of the registration and imaging unit 1. The paper ejection unit 6 stacks the paper once printing is complete.

[0012] 2 is a diagram showing an example of the configuration of a registration / imaging unit of a line head printing press according to the first embodiment. Registration / imaging unit 1 detects misalignment (and the amount of skew) in the main scanning direction using edge sensors 12a and 12b before the paper enters shift roller 11. Depending on the misalignment detection result, registration / imaging unit 1 moves shift roller 11 to a position directly facing the paper, and corrects the skew in the main scanning direction of the paper that has entered shift roller 11.

[0013] Thereafter, the registration / imaging unit 1 again detects the misalignment (and skew amount) of the paper in the main scanning direction using edge sensors 12b and 12c (edge sensor 12d for small size paper), corrects the skew in the main scanning direction, and has the leading edge of the paper gripped by gripper 13, which opens and closes mechanically and is attached to the entrance cylinder. Entrance cylinder 14, imaging drum 15, and exit cylinder 18 are connected by gears, and the paper is transported while being gripped by the attached grippers 13 one after the other.

[0014] The registration and imaging unit 1 has print heads 17 for each of the K, C, M, and Y colors. The print heads 17 may be line heads in which inkjet heads are arranged in the X-axis direction (main scanning direction). The print heads 17 eject ink to form an image as the paper 10 passes under them. The registration and imaging unit 1 determines the print timing based on the timing at which the paper passes a print timing sensor 16. An in-line sensor (scanner) 19 located at the most downstream side of the registration and imaging unit 1 (image forming section) reads the image formed on the paper, and color correction of the print head is performed based on the reading results.

[0015] Fig. 3 is a diagram showing an example of the configuration of a print head array of a line head printer according to the first embodiment. Fig. 4 is a block diagram showing an example of the configuration of a motor control controller of a line head printer according to the first embodiment. In this embodiment, as shown in Fig. 3, the line head printer (an example of a drive device) has a configuration in which a central unit (print head 17 such as a head array) is moved up and down by the power of left and right motors M1 and M2.

[0016] The print head 17 must be kept horizontal, and this is achieved by controlling the positions of two motors M1 and M2. Here, the print head 17 is an example of a unit. Brushless DC motors are used for the motors M1 and M2, and the position of the print head 17 and the speed of its up and down movement are controlled using a motor control controller C (an example of a torque control device) shown in FIG. 4. Here, the motors M1 and M2 are an example of multiple motors that drive and support the print head 17. For example, the motors M1 and M2 may be voltage-driven or current-driven DC brushless motors or DC brush motors.

[0017] Specifically, the motor control controller C has a position target setting unit 401 that sets a target position for the print head 17 (an example of a unit), which is the object to be controlled; a position controller 402 that moves the print head 17 to the target position; a speed controller 403 that controls the speed at which the print head 17 moves to the target position; an encoder 404 that detects the position of the print head 17 and outputs encoder read data that identifies the position of the print head; and a position speed conversion unit 405 that calculates the speed at which the print head 17 moves, based on the position of the print head 17 indicated by the encoder read data.

[0018] 5 is a diagram showing an example of an electrical processing block in a motor controller of a line head printer according to the first embodiment. In this embodiment, the motor controller C receives encoder read data from an external encoder 404, which identifies the position of an object to be controlled (e.g., print head 17).

[0019] In this embodiment, the motor controller C includes an encoder read data storage unit 501 , a weight calculation unit 502 , a data comparison unit 503 , a control determination unit 504 , a motor control unit 505 , and an error processing unit 506 .

[0020] The encoder read data storage unit 501 stores the encoder read data input to the motor control controller C. The weight calculation unit 502 calculates the weight of the object to be controlled (e.g., the print head 17) based on the encoder read data when the object to be controlled is in a stopped state. In this embodiment, the weight calculation unit 502 is an example of a calculation unit that calculates the mass of the print head 17 commanded by the motors M1 and M2.

[0021] A data comparison unit 503 compares the calculated weight of the object with a theoretical value (or ideal value). A control determination unit 504 determines control parameters for the motors M1 and M2 based on the difference between the weight of the object and the theoretical value. A motor control unit 505 controls the motors M1 and M2 based on the determined control parameters.

[0022] In other words, data comparison unit 503, control determination unit 504, and motor control unit 505 function as an example of a setting unit that sets the gains of motors M1, M2 based on a comparison of the calculated mass of print head 17 with an ideal value. As a result, the weight of print head 17 supported by each motor M1, M2 is calculated from the voltage output to each motor M1, M2 when an object such as print head 17 is stopped, and optimal control settings are applied to each motor according to the weight of print head 17 based on the difference between the calculated weight of print head 17 and the theoretical value, allowing motors M1, M2 to be driven with optimal control parameters.

[0023] The motor control unit 505 also functions as an example of a setting unit that sets the optimal gains (an example of control parameters) for the motors M1 and M2 based on the output ratio between the front and rear, rather than the absolute value of the mass of the print head 17. The motor control unit 505 estimates the mass of the print head 17 when stationary as follows. Output voltage to motors M1 and M2 = Output ratio (0 to 100%) x power supply voltage Output current = Output voltage / Winding resistance Output torque = output current x torque constant Mass of print head 17 = Output torque x Ball screw reduction ratio / Gravitational acceleration Here, the output ratio is the ratio of the estimated masses or the estimated output torques of the print head 17. Also, here, the front and rear refer to the multiple motors M1 and M2 that support the print head 17. However, all values except for the output ratio, ball screw reduction ratio, and gravitational acceleration contain variations, and calculation of the absolute value of the mass of print head 17 involves errors. To minimize this effect, the error is reduced by using the output ratio of motors M1 and M2. The reason the error in the mass of print head 17 can be reduced here is because the same power supply voltage is used and there is little variation in each parameter if motors M1 and M2 are from the same lot.

[0024] When the difference between the weight of the object and the theoretical value is equal to or greater than a certain value, the error processing unit 506 stops the motors M1 and M2 due to an error. That is, the error processing unit 506 is an example of a detection unit that detects an abnormality in the motors M1 and M2 when the difference between the weight of the object and the theoretical value is equal to or greater than a certain value.

[0025] 6 is a flowchart showing an example of the flow of motor control processing in the line head printer according to the first embodiment. The motor controller C moves the object to be controlled (e.g., the print head 17) to the origin (target position zero) (step S601). With the drive of the motors M1 and M2 stopped (i.e., the object to be controlled is stationary) (step S602: Yes), the weight calculation unit 502 checks the voltage output of the speed controller 403 (step S603) and calculates the weight of the object supported by each of the motors M1 and M2 (step S604).

[0026] Next, data comparison unit 503 compares the calculation result of the object's weight with the theoretical value (step S605). If the difference between the object's weight and the theoretical value is less than a certain value (step S606: No), control determination unit 504 corrects the difference (deviation) to determine optimal control parameters, and motor control unit 505 controls motors M1 and M2 based on the determined control parameters (step S607). On the other hand, if the difference between the object's weight and the theoretical value is equal to or greater than a certain value (step S606: Yes), error processing unit 506 determines that an abnormality has occurred in the object to be controlled and performs an error stop, thereby preventing machine failure (step S608).

[0027] In this way, with the line head printing machine according to the first embodiment, the weight of the print head 17 supported by each motor M1, M2 is calculated from the voltage output to each motor M1, M2 when an object such as the print head 17 is stopped, and based on the difference between the calculated weight of the print head 17 and the theoretical value, optimal control settings according to the weight of the print head 17 are applied to each motor, thereby allowing the motors M1, M2 to be driven with optimal control parameters.

[0028] (Second embodiment) This embodiment is an example in which the acceleration of the motor is limited based on the calculated mass of the print head so that the output current to the motor does not exceed the limit current of the motor. In the following explanation, explanation of the same configuration as the above-mentioned embodiment will be omitted.

[0029] In this embodiment, the two motors M1 and M2 are controlled synchronously, or the same target is assigned to two independent controls to keep the print head 17 horizontal. The following explanation is based on the assumption that two independent controls are performed on the motors M1 and M2.

[0030] When controlling motors M1 and M2, the output current to motors M1 and M2 may be limited. If the sum of the steady-state load and acceleration force on motors M1 and M2 exceeds the torque that motors M1 and M2 can output at the limited current, motors M1 and M2 can only output at the limited current, causing the behavior of motors M1 and M2 to become nonlinear. This reduces the ability of motors M1 and M2 to track the target position, and particularly in the configuration of this embodiment, this creates the problem of print head 17 not being able to remain horizontal.

[0031] To avoid this, it is necessary to operate the motors M1 and M2 so that the output current to them does not exceed the limited current. However, if the motors M1 and M2 are driven by a voltage command, it is not possible to command the output current to the motors M1 and M2. Therefore, this problem can be avoided by limiting the acceleration of the motors M1 and M2 so that there is a sufficient margin in the output current to the motors M1 and M2. However, there are significant benefits to increasing the acceleration of the motors M1 and M2 (for example, shortening the operating time). Therefore, we will explain a technique for avoiding the nonlinear behavior of the motors M1 and M2 and relaxing the limits on the acceleration of the motors M1 and M2 as much as possible.

[0032] In this embodiment, motor control unit 505 is an example of a control unit that limits the acceleration of motors M1, M2 so that the output current to motors M1, M2 does not exceed the limited current of motors M1, M2, based on the mass of print head 17 calculated by weight calculation unit 502. This makes it possible to limit the acceleration of motors M1, M2 so that the output current to motors M1, M2 has a sufficient margin, thereby avoiding nonlinear behavior of motors M1, M2 and easing the limit on acceleration of motors M1, M2 as much as possible. Furthermore, in the mechanism for lifting and lowering print head 17, it is possible to avoid non-parallelism of print head 17 due to the output limits of motors M1, M22 when print head 17 is raised.

[0033] Alternatively, the motor control unit 505 may function as an example of a designation unit that designates the target position of the print head 17 based on the mass of the print head 17 calculated by the weight calculation unit 502 so that the output current to the motors M1, M2 does not exceed the limit current of the motors M1, M2.

[0034] In this embodiment, when the print head 17 moves up and down at an angle, the weight calculation unit 502 calculates the mass of the print head 17 based on the torque that supports the vertical component of the force acting on the print head 17.

[0035] 7 is a flowchart showing an example of the flow of motor control processing in a line head printer according to the second embodiment. First, the motor control unit 505 measures the output voltage to the motors M1 and M2 when the print head 17 is stopped (step S701). Next, the motor control unit 505 calculates the output current to the two motors M1 and M2 in the stationary state (step S702). The motor control unit 505 calculates the output current by dividing the difference between the voltage command for the motors M1 and M2 and the voltage due to the back electromotive force by the winding resistance.

[0036] The motor control unit 505 calculates the output torque, which is the steady load acting on the motors M1 and M2 (for example, gravity when raising and lowering the print head 17 of a head array, etc.), from this output current (step S703). Next, the motor control unit 505 calculates the array gravity component acting on the object to be controlled (for example, the print head 17), and compares the force (output torque) required for the acceleration of the motors M1 and M2 with the array gravity component to calculate the mass of the print head 17 (step S704). The motor control unit 505 then calculates the upper limit of the acceleration of each of the motors M1 and M2 based on the mass of the print head 17, the array gravity component, and the limited current of the motors M1 and M2 (step S705). Next, the motor control unit 505 controls the motors M1 and M2 using the smaller of the upper limit of the acceleration of each of the two motors M1 and M2 (step S706). That is, the motor control unit 505 may specify a target position for raising the print head 17 so that the steady load and acceleration do not exceed the output current. The motor control unit 505 calculates the acceleration for each of the two motors M1 and M2, and sets the target position to the motor with the smaller acceleration that results in a limited current, thereby preventing a deterioration in tracking due to the limited current.

[0037] In this way, with the line head printer according to the second embodiment, the acceleration at which the output of motors M1 and M2 is limited can be determined by measuring the mass of the object to be moved when the object, such as print head 17, is stopped, and the object can be kept horizontal as long as it is below that acceleration. Also, the object can be moved within the limits of the acceleration that motors M1 and M2 can produce.

[0038] For example, aspects of the present invention are as follows. <1> a calculation unit that calculates the mass of a unit supported by a plurality of motors that drive and support the unit based on an output voltage output to each of the motors; a setting unit that sets an optimal gain for the motor based on a comparison of the calculated mass with an ideal value; A torque control device comprising: <2> a calculation unit that calculates a supported mass from an output voltage output to each of a plurality of motors that drive and support one unit; a setting unit that sets an optimal gain for the motor based on an output ratio of the plurality of motors; A torque control device comprising: <3> a calculation unit that calculates the mass of a unit based on output currents to a plurality of motors that drive and direct the unit; a control unit that limits the acceleration of the motor based on the calculated mass so that the output current does not exceed a limit current of the motor; A torque control device comprising: <4> a calculation unit that calculates the mass of a unit based on output currents to a plurality of motors that drive and support the unit; a designation unit that designates a target position of the unit based on the calculated mass so that the output current does not exceed a limit current of the motor; A torque control device comprising: <5> a detection unit that detects an abnormality when the calculated mass differs from the ideal value by a certain value or more; <1> The torque control device according to claim 1. <6> The motor is a voltage-driven DC brushless motor or a DC brush motor. <1> from <5> 10. The torque control device according to claim 9, wherein <7> The motor is a current-driven DC brushless motor or a DC brush motor. <1> from <5> 10. The torque control device according to claim 9, wherein <8> The unit moves up and down at an angle, the calculation unit calculates the mass based on a torque supporting a vertical component of a force acting on the unit. <1> from <7> 10. The torque control device according to claim 9, wherein <9> A torque control method executed by a torque control device, comprising: A step of calculating a mass of the unit supported by a plurality of motors based on an output voltage output to each of the motors that drive and support one unit; setting an optimal gain for the motor based on a mass comparison between the calculated mass and an ideal value; A torque control method comprising: <10> The unit and a plurality of motors for driving and supporting said unit; a calculation unit that calculates the mass of the unit supported by the motors based on the output voltages output to the motors; a setting unit that sets an optimal gain for the motor based on a comparison of the calculated mass with an ideal value; A drive device comprising: [Explanation of symbols]

[0039] 1. Resist / imaging unit 2. First coating unit 3 Paper feed unit 4 Drying and cooling units 5 Reversing unit 6 Paper output unit 17 Print Head 501 Encoder read data storage unit 502 Weight calculation unit 503 Data Comparison Unit 504 Control Decision Unit 505 Motor control unit 506 Error processing section C Motor Control Controller M1, M2 motors [Prior art documents] [Patent documents]

[0040] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-106948 [Patent Document 2] Japanese Patent Publication No. 2022-182345

Claims

1. a calculation unit that calculates the mass of a unit supported by a plurality of motors that drive and support the unit based on output voltages output to the motors; a setting unit that sets an optimal gain for the motor based on a comparison of the calculated mass with an ideal value; A torque control device comprising:

2. a calculation unit that calculates a supported mass from an output voltage output to each of a plurality of motors that drive and support one unit; a setting unit that sets an optimal gain for the motor based on an output ratio of the plurality of motors; A torque control device comprising:

3. a calculation unit that calculates the mass of a unit based on output currents to a plurality of motors that drive and direct the unit; a control unit that limits the acceleration of the motor based on the calculated mass so that the output current does not exceed a limit current of the motor; A torque control device comprising:

4. a calculation unit that calculates a mass of a unit based on output currents to a plurality of motors that drive and support the unit; a designation unit that designates a target position of the unit based on the calculated mass so that the output current does not exceed a limit current of the motor; A torque control device comprising:

5. The torque control device according to claim 1 , further comprising a detection unit that detects an abnormality when the calculated mass differs from the ideal value by a certain value or more.

6. 6. The torque control device according to claim 1, wherein the motor is a voltage-driven DC brushless motor or a DC brush motor.

7. 6. The torque control device according to claim 1, wherein the motor is a current-driven DC brushless motor or a DC brush motor.

8. The unit moves up and down at an angle, The torque control device according to claim 1 , wherein the calculation unit calculates the mass based on a torque supporting a vertical component of a force acting on the unit.

9. A torque control method executed by a torque control device, comprising: Calculating the mass of the unit supported by a plurality of motors based on output voltages output to each of the motors that drive and support one unit; setting an optimal gain for the motor based on a mass comparison between the calculated mass and an ideal value; A torque control method comprising:

10. The unit and a plurality of motors for driving and supporting said unit; a calculation unit that calculates the mass of the unit supported by the motors based on the output voltages output to the motors; a setting unit that sets an optimal gain for the motor based on a comparison of the calculated mass with an ideal value; A drive device comprising:

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