JP2007097365A - Motor control method and motor control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a motor from being accelerated again during a deceleration period, and to prevent the generation of noise arising from re-acceleration, in performing the speed feedback control of the motor that drives a load to be driven. <P>SOLUTION: During the deceleration period from a constant speed drive state up to a stop after deceleration, not a speed command obtained by position feedback control but a deceleration command obtained using a deceleration function which is a function of an elapsed time from the time of starting the deceleration period is used as a speed command that is inputted to a speed feedback control device. This deceleration function monotonously decreases itself and its derived function becomes a monotone function or a constant. When a carriage is driven by the deceleration command generated based on such a deceleration function, the motor is stabilized and its speed decelerates without being accelerated again during the deceleration. As a result, the generation of the noise arising from the mechanical looseness of the carriage can be prevented. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a motor control method and a motor control apparatus that perform speed feedback control so that a speed of a drive target driven by a motor matches a target speed.

  There are a wide variety of driving targets driven by a motor, for example, a carriage equipped with a recording head in a serial type printer. As a control method when the carriage is driven by a motor, a method is known in which the motor is controlled using both position feedback control and speed feedback control so that the stop position as well as the carriage speed can be controlled (for example, Patent Documents). 1).

  A specific configuration of such a motor control device using both position feedback control and speed feedback control will be described with reference to FIG. As shown in FIG. 12, the conventional motor control apparatus 100 compares the current position Xn of the control target (carriage) 107 with a preset target stop position Xt, and performs position feedback control to match the two. A position feedback (FB) control unit 101 that outputs a speed command v corresponding to the difference between the two, a speed command v (that is, a target speed) from the position feedback control unit 101, and an actual moving speed Vn of the control object 107 are obtained. A speed feedback control unit 105 that performs speed feedback control so as to match the two and generates an operation amount u to be given to the controlled object 107 is provided.

The speed command v output from the position feedback control unit 101 is not input to the speed feedback control unit 105 as it is, but the upper limit value thereof is limited to the target speed V _t by the speed command correction unit 103. It is input as a speed command vf. That is, when the speed command v from the position feedback control unit 101 is equal to or lower than the target speed V _t , the value of the speed command v is directly input to the speed feedback control unit 105 and the speed command v exceeds the target speed V _t . During this time, the target speed V _t is always input to the speed feedback control unit 105.

As described above, the motor control device 100 in FIG. 12 is configured by cascade control including two types of feedback loops. More specifically, the cascade has position information as major feedback and speed information as minor feedback. It consists of a control system. Therefore, high stop accuracy to the target stop position Xt is realized.
JP 2002-345277 A

  However, in the motor control device 100 configured with the cascade control system as described above, the positive position feedback control works on the contrary to inhibit stable speed changes during the deceleration period. Specifically, as shown in FIG. 13, re-acceleration occurs during the deceleration control. If such re-acceleration occurs during deceleration, a moment of inertia is generated in the carriage due to the acceleration / deceleration fluctuation. Then, due to the mechanical play (play) of the carriage, noise is generated during re-acceleration (acceleration / deceleration fluctuation). Such re-acceleration occurs for the following reason.

  When the carriage shifts from the constant speed drive to the deceleration control, the speed command, which has been a constant value until then, starts abruptly decreasing. However, because of the feedback control, the carriage moving speed Vn is determined by the rapid speed command. It does not respond immediately to the decline, but gradually declines. Therefore, the difference between the speed command and the actual moving speed Vn is widened.

  Then, the position feedback control unit 101 moderates the decreasing gradient of the speed command v in order to bring the delayed carriage closer to the target stop position Xt. This also appears in FIG. Although it is somewhat difficult to understand, it can be seen from the trajectory of the speed command v in FIG. 13 that the gradient at the time of decreasing is somewhat gentle near the reacceleration occurrence timing.

  Thus, when the gradient of the speed command v becomes gentle, the carriage moving speed Vn gradually becomes a speed corresponding to the speed command v. Then, the position feedback control unit 101 makes the decreasing gradient of the speed command v abrupt again. As described above, since the position feedback control unit 101 tries to realize the position control strictly, re-acceleration tends to occur as described above during the deceleration period.

  The present invention has been made in view of the above problems, and prevents the occurrence of re-acceleration during the deceleration period and the generation of noise caused by the occurrence of re-acceleration when performing speed feedback control of the motor that drives the driven object. The purpose is to do.

  The present inventor noted that the position feedback control causes the re-acceleration as described above because the speed command generated by the position feedback control is determined depending on the position transition of the carriage. did. Therefore, in order to suppress such re-acceleration, it was considered that a speed command independent of the carriage position transition should be generated. That is, position feedback control is not performed. More specifically, the inventors have come up with the idea that the speed command during deceleration can be determined depending on the time transition during deceleration.

  That is, the invention according to claim 1 made to solve the above-described problem is a motor control method for performing speed feedback control of a motor so that the speed of a driven object driven by the motor matches a preset target speed. In the deceleration control period from the preset deceleration control start timing to the stop in the drive period from the start to the stop of the driving target, the target speed is a function of the elapsed time from the deceleration control start timing. A deceleration command corresponding to the elapsed time is generated using a deceleration function, and speed feedback control is performed based on the generated deceleration command. As the deceleration function, a function is used that monotonously decreases from the deceleration control start timing until the deceleration command becomes zero, and whose derivative is monotonously decreased, monotonically increased, or constant.

  The target speed of the speed feedback control until the deceleration control period starts may be, for example, a speed trajectory that changes with time, or simply set a constant speed as a target value (target constant speed speed). Also good. Further, the target speed may be generated in any manner, for example, generated by position feedback control. That is, what the target speed until the deceleration control start timing is or how to generate it may be determined as appropriate.

  In the motor control method of the present invention, a deceleration command obtained from a time-dependent deceleration function is generated as the target speed in the deceleration control period, and speed feedback is performed based on the deceleration command. Since this deceleration function is a function of the elapsed time from the deceleration control start timing, the deceleration command is uniquely determined according to the elapsed time. In other words, once the elapsed time is known, the deceleration command at that time can be calculated based on the deceleration function.

  And as this deceleration function, it decreases monotonically from the deceleration control start timing until the deceleration command becomes zero, and the derivative (function differentiated with respect to time) becomes a monotone function or a constant. Use functions.

  The monotonic decrease / monotonic increase here has a broad meaning. That is, a case where a portion that becomes constant in the process of increase or decrease is included. However, since one of the conditions of the deceleration function is that the derivative is a monotonic function or a constant, the deceleration function itself inevitably does not have a period during which the deceleration command becomes constant during the monotonically decreasing process. It will be.

  As a deceleration function that satisfies such conditions, for example, a linear function having a negative slope, a quadratic function having an upward convexity to the right side from the local maximum value (a portion that monotonically decreases from the local maximum value), and a convex quadratic function having a downward slope Left from the minimum value in the function (the part that decreases monotonically toward the minimum value), left side from the inflection point in the monotonically decreasing cubic function (the part that decreases monotonically toward the inflection point), and cosine function Various things can be considered, such as the right side (the part that monotonously decreases) from the origin in None of these functions are functions such as the velocity command v shown in FIG.

  Thus, the motor control method of the present invention (Claim 1) does not use position feedback control as the control method of the deceleration control period, and simply depends on the elapsed time from the start point of the deceleration control period according to the deceleration function described above. Obtained deceleration command. Then, speed feedback control is performed based on a deceleration command according to the deceleration function.

  Therefore, it is possible to prevent the speed of the drive target being decelerated from being accelerated again during the deceleration control period. Then, it is possible to prevent the generation of noise caused by the re-acceleration (that is, unstable speed change such as deceleration, acceleration, and deceleration).

  The motor control method according to the first aspect can be specifically realized by, for example, the motor control apparatus according to the second aspect. That is, the motor control device according to claim 2 is set by a speed detection means for detecting the speed of the drive target driven by the motor, a target speed setting means for setting the target speed of the drive target, and a target speed setting means. The target speed and the speed detected by the speed detection means are compared, and the speed feedback control means for performing the speed feedback control of the motor so as to match them, and the drive period from the start to the stop of the drive of the drive target are set in advance. And a deceleration command generating means for generating a deceleration command that is a target speed to be driven in a deceleration control period from the start timing of the deceleration control to the stop.

  The speed feedback control means performs speed feedback control based on the deceleration command generated by the deceleration command generation means during the deceleration control period, and the deceleration command generation means is a deceleration function that is a function of an elapsed time from the deceleration control start timing. A deceleration command according to the elapsed time is generated using the function. This deceleration function is a function that monotonously decreases from the deceleration control start timing until the deceleration command becomes zero, and the derivative thereof monotonously decreases, monotonically increases, or becomes a constant.

  According to the motor control apparatus configured as described above, during the deceleration control period, the deceleration command generation means generates a deceleration command based on the deceleration function, and the speed feedback control means performs speed feedback control based on the deceleration command. Do. Therefore, the effect of preventing the occurrence of reacceleration during the deceleration control period and the noise caused by the occurrence of reacceleration can be obtained as in the first aspect.

  Note that the speed of the object to be driven until immediately before the deceleration control start timing may be a constant speed or during acceleration or deceleration. That is, the present invention is not limited to starting deceleration from the deceleration control start timing at which the deceleration control period starts. The deceleration control start timing is not limited to the timing at which deceleration starts, but to the timing at which speed feedback control based on the deceleration command from the deceleration command generation means is started.

  Here, as the deceleration function used by the deceleration command generation means to generate the deceleration command, various functions can be considered as exemplified above. For example, as described in claim 3, the deceleration function is a downward convex function. Good. Needless to say, a downwardly convex deceleration function, but when the deceleration function in the deceleration control period is graphed (represented on a two-dimensional coordinate with a time axis and a deceleration command axis), any point on the graph This means that the function is such that the graph exists above the tangent. In other words, the function is such that the gradient gradually decreases with time.

  When using the deceleration function represented by a downward convex function in this way, the deceleration command first decreases sharply (with a steep slope) at the deceleration control start timing, and the slope gradually becomes gentle, When it stops at the end, the slope is the slowest (almost no slope). Therefore, it is possible to stop the drive target in a stable state / speed.

  On the other hand, when using a deceleration function represented by an upwardly convex function, the effect of preventing re-acceleration and noise can be obtained, but the deceleration command slowly decreases from the deceleration control start timing. The decreasing gradient becomes steeper and the last stop is the steepest. That is, the change in the deceleration command immediately before the stop becomes intense. Therefore, it may be difficult to stop at a stable state / speed. Therefore, it is preferable to use a deceleration function represented by a downward convex function in consideration of stability and accuracy at the time of stopping.

  By the way, by generating a deceleration command according to the elapsed time from the deceleration control start timing using the deceleration function as described above, it is possible to obtain a deceleration command that prevents the drive target from being accelerated again during the deceleration control. However, since position feedback control is not necessarily performed, it is difficult to stop at a desired stop position with a deceleration function that simply satisfies the above-described conditions.

  Therefore, for example, a deceleration function as described in claim 4 may be used so that the drive target can be stopped at a desired position. That is, the invention according to claim 4 is the motor control device according to claim 2 or 3, wherein a deceleration distance setting that sets a deceleration distance that is a distance from a deceleration control start timing to a preset target stop position is set. The deceleration function is a function such that an integrated value when the deceleration function is integrated from the deceleration control start timing to the time when the deceleration command becomes zero coincides with the deceleration distance.

  Since the deceleration function is a function of a deceleration command (target speed given to the speed feedback control means) with respect to the elapsed time, if it is integrated over time, a moving distance within that time can be obtained. Therefore, if a deceleration function is used so that the integral value until the deceleration command becomes zero becomes the deceleration distance, theoretically, when the deceleration command becomes zero, the drive target also stops at the target stop position. It will be.

  Therefore, according to the motor control device having the above-described configuration, the deceleration command is generated by the deceleration function such that the time integration value from the deceleration control start timing until the deceleration command becomes zero becomes the deceleration distance set by the deceleration distance setting means. In addition to preventing re-acceleration during the deceleration period and the generation of noise due to it, it is also possible to stop the drive target at the desired stop position (target stop position), and stop accuracy A good motor control device can be obtained.

  Actually, there is a possibility that the vehicle stops at a position slightly deviated from the target stop position due to the influence of friction, mechanical characteristics of the driven object, and the like. However, the deviation is not at a level that causes a practical problem.

  The deceleration distance setting means may directly set the deceleration distance itself. For example, when the position is given as the deceleration control start timing, the distance between the position and the target stop position can be calculated. It may be set by obtaining.

  When the deceleration control is performed using the deceleration function whose integrated value matches the deceleration distance in order to stop the driving target at the target stop position as described above, the driving target is displayed before the deceleration command becomes zero. It is also conceivable that the target stop position has already been reached. In this case, if speed feedback control based on the deceleration command is performed even after reaching the target stop position, the drive target advances further than the target stop position.

  Therefore, for example, as described in claim 5, arrival detection means for detecting whether or not the drive target has reached the target stop position, and braking control means for performing brake control of the motor so that the drive target stops. If the arrival detection means detects that the drive target has reached the target stop position, the speed feedback control means stops the speed feedback control based on the deceleration command, and the braking control means executes the braking control. It is good to make it.

  According to the motor control device configured as described above, even when the speed feedback control based on the deceleration command is being executed, the drive target is stopped by the braking control when the drive target reaches the target arrival position. For this reason, it is possible to accurately stop the drive target at the target stop position.

  The invention according to claim 6 is the motor control device according to claim 4 or 5, further comprising an initial deceleration command setting means for setting an initial deceleration command that is a deceleration command at the deceleration control start timing, The command generating means includes a deceleration function deriving means for deriving a deceleration function based on the deceleration distance set by the deceleration distance setting means and the initial deceleration command set by the initial deceleration command setting means, and a timing means for timing the elapsed time; And a deceleration command calculating means for calculating a deceleration command corresponding to the elapsed time measured by the timing means according to the deceleration function derived by the deceleration function deriving means.

  That is, the deceleration function deriving unit derives a deceleration function based on the preset deceleration distance and the initial deceleration command. This derivation method will be outlined with reference to FIG. FIG. 11 is an example of a deceleration function r (t) representing a deceleration command from the deceleration control start timing (t = 0), and here, a linear function is shown for the sake of simplicity of explanation.

  Since the deceleration function r (t) is a linear function, r (t) = − At + V. A is an unknown coefficient. Also, the elapsed time τ until the deceleration command becomes zero is unknown at present. Here, it is known in advance that the deceleration function r (t) passes through the point (τ, 0) and that the result of integrating r (t) between t = 0 and τ is the deceleration distance x. ing. Therefore, A and τ are obtained by calculation.

  Although the linear function is illustrated in FIG. 11, the deceleration function r (t) can be derived in the same manner even in the case of other functions. For example, in the case of deriving the deceleration function r (t) with an upwardly convex function, an expression is set so that the function takes a maximum value at t = 0, and the unknown coefficient in the expression is set as described above. , Passing through the point (τ, 0), and the integral value may be calculated based on the deceleration distance x.

  According to the motor control device configured as described above, the deceleration function is derived based on the preset deceleration distance and the initial deceleration command, and the elapsed time measured by the time measured according to the derived deceleration function. A corresponding deceleration command is calculated. Therefore, motor control devices having various deceleration characteristics can be constructed by changing the set values of the deceleration distance and the initial deceleration command.

  The initial deceleration command setting means is not limited to the one that actively sets the initial deceleration command as the deceleration command at the deceleration control start timing, and may be anything as long as it corresponds to the initial deceleration command setting means. For example, if there is a means to start speed feedback control by a deceleration command after driving at a constant speed for a certain period, and there is a means for setting a target speed in that constant speed driving period, it also functions as an initial deceleration command setting means Will be.

  The motor control device of the present invention (Claims 2 to 6) can be applied to various driving objects driven by a motor. For example, as described in Claim 7, a carriage mounted on the image forming apparatus. As described above, it is more effective when applied to a driving object that repeats reciprocating motion (a driving object that repeats acceleration, constant speed, deceleration, and stop).

  That is, the invention according to claim 7 is the motor control device according to any one of claims 2 to 6, wherein the motor control device has a function of forming an image on the recording medium while conveying the recording medium. The drive target mounted on the image forming apparatus provided is a carriage that reciprocates in the main scanning direction perpendicular to the transport direction by mounting recording means for forming an image on a recording medium.

  Thus, by applying the motor control device to the reciprocating movement of the carriage, re-acceleration when the carriage decelerates and stops is prevented. Therefore, noise generated by mechanical play (play) of the carriage at the time of re-acceleration can be prevented, and an image forming apparatus having a quiet operation sound and comfortable for the user can be provided.

Preferred embodiments of the present invention will be described below with reference to the drawings.
(1) Configuration of Carriage Drive Mechanism FIG. 1 is an explanatory diagram showing the configuration of a carriage drive mechanism in an ink jet printer (hereinafter simply referred to as “printer”) as an image forming apparatus to which the motor control device of the present invention is applied. is there.

  This carriage drive mechanism first records a recording head that performs recording by ejecting ink from a nozzle toward the printing paper 33 on a guide shaft 34 installed in the width direction of the printing paper 33 conveyed by the pressing roller 32 or the like. A carriage 31 carrying 30 is inserted.

  The carriage 31 is connected to an endless belt 37 provided along the guide shaft 34, and the endless belt 37 includes a pulley 36 of a CR motor 35 installed at one end of the guide shaft 34 and the other end of the guide shaft 34. It is latched between idle pulleys (not shown) installed in That is, the carriage 31 is configured to reciprocate in the width direction of the printing paper 33 along the guide shaft 34 by the driving force of the CR motor 35 transmitted via the endless belt 37.

  A timing slit 38 is formed along the guide shaft 34 below the guide shaft 34. The timing slit 38 is formed with a slit having a constant width at regular intervals (1/150 inch = about 0.17 mm in this embodiment). ing.

  A detection unit (not shown) made of a photo interrupter is provided below the carriage 31 so that the light emitting element and the light receiving element face each other with the timing slit 38 interposed therebetween. In addition, a linear encoder 39 (see FIG. 4) described later is configured.

  As shown in FIG. 2, the detection unit constituting the linear encoder 39 outputs two types of encoder signals ENC1 and ENC2 that are shifted from each other by a constant cycle (in this embodiment, a quarter cycle). When the moving direction of the carriage 31 is the forward direction from the home position (the left end position in FIG. 1) toward the idle pulley, the phase of ENC1 advances by a certain period with respect to ENC2, and from the idle pulley to the home position. In the reverse direction, the phase of ENC1 is delayed by a certain period with respect to ENC2.

In such a carriage drive mechanism, as shown in FIG. 3, the carriage 31 has a home position set in the vicinity of the pulley 35 side end of the guide shaft 34 or the previous recording is completed when the recording process is not performed. When the recording process is started, acceleration is performed so that the target speed is reached before reaching the preset recording start position (hereinafter referred to as “origin”). After that, it moves at a predetermined target speed until reaching a preset recording end position, and when it exceeds the recording end position, it is decelerated until it stops. (2) Configuration of Carriage Control Device Further, as shown in FIG. 4, the printer includes a CPU 2 that controls the printer, an ASIC that generates a PWM signal that controls the rotation speed, rotation direction, and the like of the CR motor 35. Application Specific Integrated Circuit) 3, carriage control including a motor drive circuit (CR drive circuit) 4 that drives the CR motor 35 by controlling the four FETs in the H-bridge circuit based on the PWM signal generated in the ASIC 3. The device 1 is built in.

  The ASIC 3 includes a register group 5 that stores various parameters used to control the CR motor 35, a carriage positioning unit 6 that calculates the position and moving speed of the carriage 31 based on encoder signals ENC1 and ENC2 acquired from the linear encoder 39, and a deceleration start position. Stored in the register group 5 and the deceleration command generation unit 10 that generates a deceleration command r (td) (td: elapsed time from the deceleration start position) as a target speed used by the motor control unit 7 during the deceleration period from to the target stop position. The motor control unit 7 that generates a motor control signal for controlling the rotational speed of the CR motor 35 based on the various parameters and the data from the carriage positioning unit 6, and the duty according to the motor control signal generated by the motor control unit 7 PWM generator 8 for generating a ratio PWM signal, encoder signals ENC1, ENC A clock generator 9 supplies more fully cycle is shorter clock signal inside the respective portions ASIC3 is provided.

Among these, the register group 5 starts the start setting register 50 for starting the CR motor 35, the target stop position setting register 51 for setting the target stop position where the carriage 31 should be stopped, and the deceleration of the carriage 31. The deceleration start position setting register 52 for setting the deceleration start position (same as the recording end position; corresponding to the position to be driven at the deceleration control start timing of the present invention), the target speed V _t that the carriage 31 should target (image) The target speed setting register 53 for setting the constant speed driving speed during recording), the speed control gain used for speed feedback calculation when the motor control section 7 controls the CR motor 35, etc. It is configured by a control unit parameter setting register 54 for setting various parameters to be used. Incidentally, the target speed V _t is because it is the deceleration instruction when the deceleration control is started at the deceleration start position (the initial value of the deceleration command) may be those corresponding to the initial deceleration command of the present invention.

  The carriage positioning unit 6 also detects an edge detection signal indicating the start / end of each cycle of the encoder signal ENC1 based on the encoder signals ENC1 and ENC2 from the linear encoder 39 (here, the edge of ENC1 when ENC2 is at a high level). And an edge detection unit 60 that detects the rotation direction of the CR motor 35 (forward direction if the edge detection signal is the falling edge of ENC1, and reverse direction if the edge detection signal is the rising edge), and the CR motor 35 detected by the edge detection unit 60. By counting up (in the forward direction) or counting down (in the reverse direction) the edge detection signal in accordance with the rotation direction (that is, the movement direction of the carriage 31), the carriage 31 is positioned at which slit from the home position. Position counter 61 for detecting whether or not, edge detection unit 6 Counter 63 that counts the generation interval of the edge detection signal from the clock signal, the distance (1/150 inch) between the slits of the timing slit 38, and the holding value Cn of the value counted by the period counter 63 in the previous period of the encoder signal ENC1 -1 and the time tn-1 (= Cn-1 × clock cycle) specified by the speed conversion unit 64 that calculates the moving speed of the carriage 31, and the count value by the position counter 61 is the target stop position setting register 51. And an interrupt processing unit 65 that outputs a stop interrupt signal to the CPU 30 when the target stop position is set to or higher.

Further, the motor control unit 7, as shown in FIG. 5, one of the target speed set in the target speed setting register 53 V _t or generated by deceleration command generator 10 a deceleration command r (td) selected, a speed command selection section 71 to be input to the speed feedback control section 75 as a speed command, a velocity command input from the speed command selection section 71 (either the target velocity V _t or deceleration command r (td)) A speed feedback control unit 75 that generates a manipulated variable u by performing speed feedback control (for example, PID control) to match the moving speed of the carriage 31 calculated by the speed conversion unit 64 is provided.

In the motor control unit 7, the speed command selection unit 71 switches the target speed V _t set in the target speed setting register 53 or the deceleration command r (td) generated by the deceleration command generation unit 10 with the switch 73. It is configured to be possible. This switch 73 is used when the current position Xn of the carriage 31 determined from the count value of the position counter 61 is smaller than the deceleration start position set in the deceleration start position setting register 52, that is, the carriage 31 is set to the deceleration start position. until the reach to a state of switching to the target speed V _t side, the current position Xn of the carriage 31, when in a set deceleration start position than the deceleration start position setting register 52, i.e. the carriage 31 After reaching the deceleration start position, it is configured to switch to the deceleration command r (td) side.

In the speed feedback control unit 75, the difference between the speed command from the speed command selection unit 71 and the moving speed Vn of the carriage 31 from the speed conversion unit 64 is calculated by the adder 77, and the speed is calculated based on the calculation result. PID control is performed by the controller 78 to calculate the operation amount u. That is, speed feedback control based on the target speed V _t is performed until the carriage 31 reaches the deceleration start position, and after the carriage 31 reaches the deceleration start position, speed feedback control based on the deceleration command r (td) is performed. It is done.

  Further, the deceleration command generation unit 10 that generates the deceleration command r (td) in the ASIC 3, as shown in FIG. 4, derives a deceleration function r (t) that is a source for generating the deceleration command. 11, a time measuring unit 13 that measures an elapsed time td after the carriage 31 reaches the deceleration start position, and a deceleration command that calculates a deceleration command r (td) at the elapsed time td using the deceleration function r (t). And an arithmetic unit 15.

The deceleration function deriving unit 11 of the present embodiment is preset to derive a downward convex quadratic function as shown in FIG. 6 as the deceleration function r (t). As will be described later, the deceleration function r (t) is derived every time the carriage 31 is driven once, that is, every time the reciprocating drive in the main scanning direction is repeated one by one. Then, the derivation is the target stop position set in the register group 5, the deceleration start position, and is performed on the basis of the target speed V _t.

(3) Derivation method of deceleration function r (t) A method of deriving the deceleration function r (t) performed by the deceleration function deriving unit 11 will be schematically described with reference to FIG. In the graph of FIG. 6, the horizontal axis represents the elapsed time after reaching the deceleration start position, and the vertical axis represents the deceleration command r (td). Here, as a deceleration function r (t) to be derived (secondary function in this example), a waveform is set so that the deceleration command becomes zero when a certain time τ has elapsed from the start of deceleration (t = 0). To do. Note that this quadratic function takes a minimum value at t = τ.

  Therefore, this function r (t) can be expressed as the following equation (1). A is a proportionality constant.

Since this deceleration function passes through the point (0, V _t ), the equation (1) can be expressed as the following equation (2).

  On the other hand, since the deceleration start position and the target stop position are known, the deceleration distance x, which is the movement distance from the deceleration start to the stop, is known in advance by the difference between the two. Since this deceleration distance x coincides with the value obtained by integrating the deceleration function r (t) over the time from t = 0 to τ, the following expression (3) is obtained.

Then, from the above two formulas (2) and (3), τ and A are obtained as the following formula (4).

Accordingly, the deceleration function r (t) is obtained as in the following equation (5).

  If the deceleration function r (t) of the above formula (5) is derived by the deceleration function deriving unit 11, the elapsed time td using the deceleration function r (t) is subsequently used by the deceleration command calculating unit 15. The deceleration command r (td) at is calculated. Therefore, when the carriage 31 starts decelerating after reaching the deceleration start position, the deceleration command r (td) also decreases along the waveform of the deceleration function r (t) shown in FIG. Become.

  The locus of the deceleration command r and the actual moving speed Vn of the carriage 31 when the deceleration control (speed feedback control) of the carriage 31 is performed based on the deceleration command generated by the deceleration command generation unit 10 in this way. Is shown in FIG.

  As is clear from comparison between FIG. 7 and the conventional FIG. 13, in this embodiment, the moving speed Vn of the carriage 31 is decelerated without reacceleration. This result is obtained because the position feedback control is not used in the present embodiment, and a speed reduction control command according to a speed reduction function r (t) represented by a downward convex quadratic function is simply sent to the speed feedback control unit. This is because it is given to 75.

  The deceleration function r (t) is not only a monotonically decreasing function itself, but also the derivative dr (t) / dt is a monotone function (monotonically increasing function). By giving a deceleration command corresponding to the elapsed time using such a deceleration function r (t), the actual moving speed Vn is prevented from being accelerated again. Since the re-acceleration is prevented, the carriage 31 can be stably stopped, and the generation of noise due to the play (play) of the carriage 31 is also prevented.

  Note that the carriage moving speed Vn suddenly drops to zero around the time t = 0.2 [sec]. This is because the linear encoder 39 cannot detect the amount of movement until the target stop position is reached at this timing and the braking control described later has been performed and until the brake stops completely. Due to the amount.

(4) Processing executed by CPU and ASIC The contents of the CR scanning processing executed by the CPU 2 will be described below with reference to FIG.
When this process is started, first, an initial process for the ASIC 3 is executed (S110). In this initial processing, setting of each register constituting the register group 5 is performed. When this process ends, the CPU 2 issues a stop interrupt permission from the CPU 2 to the ASIC 3 (S120). As a result, the ASIC 3 can output a stop interrupt signal.

  The ASIC 3 that has received the stop interrupt permission detects the state by the interrupt processing unit 65 every time the carriage 31 stops at the target stop position set in the target stop position setting register 51, and outputs a stop interrupt signal. Input to CPU2.

  When the process in S120 is completed, the CPU 2 performs activation setting for the ASIC 3 (S130). That is, in S130, triggered by the setting of the activation setting register 50 by the CPU 2, the calculation of the operation amount u is started on the ASIC 3 side, and the driving of the CR motor 35 and the driving of the carriage 31 are started. The control of the CR motor 35 that is started after the start setting is basically performed by the ASIC 3, and the CPU 2 waits for a stop interrupt signal in S140.

  When a stop interrupt signal is output from the ASIC 3, the stop interrupt flag is cleared by the CPU 2, and an interrupt mask process for the stop interrupt is executed so that the stop interrupt signal will not be input thereafter (S150).

  Here, a procedure in which the motor control unit 7 of the ASIC 3 generates the operation amount u after the ASIC 3 is activated by the CPU 2 by the CR scanning process of FIG. 8 will be described based on FIG. The motor control unit 7 is configured to execute the following control operation as a so-called hardware circuit. Here, for easy understanding, the control operation as the hardware circuit is shown in a flowchart. It replaces and explains.

First, the deceleration distance x from the deceleration start position to the target stop position is calculated by calculating the difference between the target stop position and the deceleration start position set in the register group 5 (S210). Then, the deceleration function r (t) is derived using the calculated deceleration distance x and the target speed V _t set in the register group 5 (S220). The processes of S210 and S220 are performed by the deceleration function deriving unit 11, and the specific method for deriving the deceleration function r (t) is as described above.

After deriving the deceleration function r (t), the target speed V _t set in the target speed setting register 53 is selected by the switch 73 of the speed command selection unit 71 (S230). Thereafter, the speed feedback control by the speed feedback control unit 75 is started (S240).

  Then, it waits until it reaches the deceleration start position (S250), and when it reaches the deceleration start position (S250: YES), it starts counting the elapsed time td by the timing unit 13 (S260), and the switch of the speed command selection unit 71 73, the deceleration command r (td) from the deceleration command generator 10 is selected (S270). Thereafter, the calculation of the deceleration command r (td) by the deceleration command calculation unit 15 is started (S280), and the deceleration command r (td) corresponding to the elapsed time td at every predetermined interval is sent to the motor control unit 7. Entered.

  When the carriage 31 reaches the target stop position (S290: YES), even if the deceleration command r (td) is still a finite value, the operation of the deceleration command generation unit 10 is stopped and the speed feedback control unit 75 is stopped. Is output an operation amount (braking command) for stopping the carriage 31 (S300). That is, the braking control for immediately stopping the carriage 31 is performed. Then, when the carriage 31 is completely stopped (S310: YES), this carriage driving sequence is once ended.

(5) Effects of Embodiments As described above, in the carriage control device 1 of the present embodiment, the position feedback control is not used as a control method for the deceleration period after reaching the deceleration start position, and the deceleration function r is simply used. According to (t), a method is employed in which a deceleration command r (td) corresponding to the elapsed time td from the start time of the deceleration period is calculated, and speed feedback control based on the deceleration command r (td) is performed.

  Therefore, it is possible to prevent the speed of the carriage 31 being decelerated from being accelerated again during the deceleration period. Then, it is possible to prevent the generation of noise caused by the re-acceleration (that is, unstable speed change such as deceleration, acceleration, and deceleration).

  The deceleration function r (t) is derived as a downward convex quadratic function. Therefore, after reaching the deceleration start position, the deceleration command decreases rapidly (with a steep slope), the slope gradually becomes gentle, and the slope is the slowest when it stops at the end (almost no slope). It becomes a state. Therefore, the carriage 31 can be stopped at a stable state / speed.

  Furthermore, in deriving the deceleration function r (t), the deceleration function r (t) is derived so that the integrated value from the deceleration start time to the stop time coincides with the deceleration distance x. Accordingly, since the carriage 31 also stops at or near the target stop position when the deceleration command becomes zero, it is possible to provide the carriage control device 1 with high stop position accuracy.

  Furthermore, during the deceleration control, when the carriage 31 reaches the target stop position, the operation of the deceleration command generation unit 10 is stopped and the braking control is performed to stop the carriage 31 quickly. Therefore, the stop position accuracy of the carriage 31 is further increased.

  In this embodiment, the present invention is applied to the carriage drive of the ink jet printer, and the carriage 31 is prevented from being reaccelerated during the deceleration period from the start of deceleration to the stop of the carriage 31. Therefore, noise caused by mechanical backlash when the carriage 31 is reciprocated is prevented, and a printer with quiet operation sound is realized.

Here, the correspondence between the components of the present embodiment and the components of the present invention will be clarified. In this embodiment, the speed feedback control unit 75 corresponds to the speed feedback control unit of the present invention, the deceleration command generation unit 10 corresponds to the deceleration command generation unit of the present invention, and the deceleration function derivation unit 11 corresponds to the deceleration function of the present invention. The timing unit 13 corresponds to the timing unit of the present invention, the deceleration command calculation unit 15 corresponds to the deceleration command calculation unit of the present invention, the recording head 30 corresponds to the recording unit of the present invention, and the register. It sets the target speed V _t to the group 5 CPU 2 corresponds to the target speed setting means and the initial deceleration command setting means of the present invention.

  In the carriage drive sequence of FIG. 9, the process of S210 corresponds to the process executed by the deceleration distance setting means of the present invention, the process of S290 corresponds to the process executed by the arrival detection means of the present invention, and the process of S300 Corresponds to the processing executed by the braking control means of the present invention.

(6) Modifications It should be noted that the embodiment of the present invention is not limited to the above-described embodiment, and it goes without saying that various forms can be adopted as long as it belongs to the technical scope of the present invention.

For example, in the above embodiment, the deceleration function r (t) is a downward convex quadratic function. However, this is merely an example. For example, a deceleration function that becomes an upward convex quadratic function is used. It may be derived. A specific derivation method in this case will be described with reference to FIG. When the deceleration function r (t) is expressed by a quadratic function convex upward as shown in FIG. 10, the quadratic function takes a maximum value V _t at t = 0.

  Therefore, this function r (t) can be expressed as the following equation (6). A is a proportionality constant.

Since this deceleration function passes through the point (τ, 0), the equation (6) can be expressed as the following equation (7).

  On the other hand, the deceleration distance x is known in advance, and this deceleration distance x coincides with the value obtained by integrating the deceleration function r (t) with the time from t = 0 to τ, so that the following equation (8) is obtained. .

Then, τ and A are obtained from the above two equations (7) and (8). As a result, the deceleration function r (t) is obtained as in the following equation (9).

Even using the deceleration function r (t) of the equation (9) obtained in this way, the occurrence of re-acceleration during the deceleration period is prevented, and the generation of noise in the carriage 31 is prevented.
Up to this point, the case where the deceleration function r (t) is expressed by a quadratic function has been described, but it is needless to say that the function is not limited to a quadratic function. It may be a linear function or a function of cubic or higher. Alternatively, a cosine function may be used.

  That is, the function may be any function that does not cause the carriage 31 to re-accelerate during the deceleration period. Specifically, the function decreases monotonically from the deceleration start position until the deceleration command becomes zero, and Any function whose derivative is monotonically decreasing, monotonically increasing, or constant may be used.

The monotonic decrease / monotonic increase here has a broad meaning.
Therefore, for example, when deriving the deceleration function r (t) using the downward convex n-order function (where n is an even number) including the downward convex quadratic function, first, the deceleration function r (t) Is given by the following equation (10).

Then, by performing the calculation in the same manner as described above, the deceleration function r (t) can be expressed by the following equation (11).

In other words, when the deceleration function r (t) is expressed by a function having an even degree convex downward, the above equation (11) may be used.
Further, for example, when the deceleration function r (t) is derived using the upward convex even function and the odd order function including the upward convex quadratic function, the deceleration function r (t) is first expressed as follows. What is necessary is just like Formula (12).

The deceleration function r (t) can be expressed by the following equation (13) by performing the calculation in the same manner as described above.

That is, when the deceleration function r (t) is expressed by an even-order function and an odd-order function that are convex upward, the above equation (13) may be used.
In the above embodiment, the quadratic function is used in advance as the deceleration function r (t). However, the type of function to be derived by the deceleration function deriving unit 11 is selected from the outside. You may comprise so that it can do. For example, a register for setting the function type may be provided in the register group 5 so that the function corresponding to the value of the register can be derived by the deceleration function deriving unit 11.

It is explanatory drawing showing the structure of the carriage drive mechanism in the inkjet printer of this embodiment. It is explanatory drawing showing the output pattern of an encoder signal. It is a graph showing the movement state of a carriage. It is a block diagram showing schematic structure of a carriage control apparatus. It is a block diagram showing the structure of the motor control part which comprises a carriage control apparatus. It is explanatory drawing for demonstrating the deceleration function r (t) represented by a downward convex quadratic function. It is a graph showing transition of the deceleration instruction | command r and the carriage moving speed Vn in the deceleration period of this embodiment. It is a flowchart showing the carriage scanning process performed by CPU. It is a flowchart showing the procedure of the carriage drive sequence performed by ASIC. It is explanatory drawing for demonstrating the modification (upward convex quadratic function) of the deceleration function r (t). It is explanatory drawing for demonstrating the deriving method of the deceleration function by the deceleration function deriving means of this invention. It is a block diagram showing the motor control apparatus by the conventional cascade control system. 13 is a graph showing changes in a speed command v and a carriage moving speed Vn during a deceleration period by the motor control device of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Carriage control apparatus, 5 ... Register group, 6 ... Carriage positioning part, 7 ... Motor control part, 8 ... PWM generation part, 9 ... Clock generation part, 10 ... Deceleration command generation part, 11 ... Deceleration function deriving part, 13 DESCRIPTION OF SYMBOLS: Time measuring part, 15 ... Deceleration command calculating part, 30 ... Recording head, 31 ... Carriage, 33 ... Printing paper, 35 ... CR motor, 39 ... Linear encoder, 50 ... Start setting register, 51 ... Target stop position setting register, 52 ... deceleration start position setting register, 53 ... target speed setting register, 54 ... control unit parameter setting register, 60 ... edge detection unit, 61 ... position counter, 63 ... period counter, 64 ... speed conversion unit, 65 ... interrupt processing unit , 71 ... Speed command selection unit, 73 ... Switch, 75 ... Speed feedback control unit, 77 ... Adder, 78 ... Speed controller

Claims (7)

A motor control method for performing speed feedback control of the motor so that a speed of a drive target driven by the motor matches a preset target speed,
In the deceleration control period from the preset deceleration control start timing to the stop of the drive period from the start of driving to the stop of the drive target, deceleration that is a function of the elapsed time from the deceleration control start timing is used as the target speed. Generate a deceleration command according to the elapsed time using a function, perform the speed feedback control based on the generated deceleration command,
A motor that uses a function that monotonously decreases from the deceleration control start timing until the deceleration command becomes zero and whose derivative is monotonously decreased, monotonically increased, or constant as the deceleration function. Control method. Speed detecting means for detecting the speed of the driven object driven by the motor;
Target speed setting means for setting the target speed of the drive target;
A speed feedback control means for comparing the target speed set by the target speed setting means with the speed detected by the speed detection means and performing speed feedback control of the motor so as to match the two;
Deceleration command generating means for generating a deceleration command that is a target speed of the drive target in a deceleration control period from a preset deceleration control start timing to a stop of a drive period from the start to stop of the drive target; Prepared,
The speed feedback control means performs the speed feedback control based on the deceleration command generated by the deceleration command generation means in the deceleration control period,
The deceleration command generation means generates the deceleration command according to the elapsed time using a deceleration function that is a function of the elapsed time from the deceleration control start timing,
The motor is characterized in that the deceleration function is a function that monotonously decreases from the deceleration control start timing until the deceleration command becomes zero, and the derivative thereof monotonously decreases, monotonically increases, or becomes a constant. Control device. The motor control device according to claim 2,
The motor control device according to claim 1, wherein the deceleration function is a downward convex function. The motor control device according to claim 2 or 3,
A deceleration distance setting means for setting a deceleration distance that is a distance from the deceleration control start timing to a preset target stop position;
The motor control device, wherein the deceleration function is a function such that an integrated value when the deceleration function is integrated from the deceleration control start timing to a time when the deceleration command becomes zero coincides with the deceleration distance. . The motor control device according to claim 4,
Arrival detection means for detecting whether or not the drive target has reached the target stop position;
Braking control means for performing braking control of the motor so that the drive target stops,
If it is detected by the arrival detection means that the drive target has reached the target stop position, the speed feedback control means stops the speed feedback control based on the deceleration command, and the braking control means A motor control device that executes control. The motor control device according to claim 4 or 5,
An initial deceleration command setting means for setting an initial deceleration command which is the deceleration command at the deceleration control start timing;
The deceleration command generation means includes
Deceleration function deriving means for deriving the deceleration function based on the deceleration distance set by the deceleration distance setting means and the initial deceleration command set by the initial deceleration command setting means;
A time measuring means for measuring the elapsed time;
A motor control device, comprising: a deceleration command calculating unit that calculates the deceleration command corresponding to the elapsed time measured by the timing unit according to the deceleration function derived by the deceleration function deriving unit. The motor control device according to claim 2,
The motor control device is mounted on an image forming apparatus having a function of forming an image on a recording medium while conveying the recording medium,
The motor control device according to claim 1, wherein the driving target is a carriage that mounts recording means for forming an image on the recording medium and reciprocates in a main scanning direction orthogonal to the transport direction.