JP2022114323A - Vibration actuator control device and lens device - Google Patents

Abstract

To suppress overshoot with respect to a target location.SOLUTION: In the forward direction with respect to the direction of an external force acquired, a control CPU 120 controls a vibration body 103 by adding a driving force on the opposite direction to a driving direction to a driving force based on a target location at least when starting driving of a mobile body to the target location. In other words, when the driving direction is in the forward direction with respect to the direction of the external force, the control CPU 120 adds an initial phase difference of a polarity opposite a polarity of a phase difference operation amount to the phase difference operation amount.SELECTED DRAWING: Figure 6

Description

The present invention relates to a vibratory actuator control device and a lens device.

A vibration-type actuator generally has a vibrating body that excites vibration such as an elliptical motion by applying two-phase frequency driving signals having a phase difference to a piezoelectric element, and a contact body that contacts the vibrating body. A movable one of vibrating bodies and contact bodies (hereinafter referred to as a moving body) moves. That is, the vibrating body and the contact body move relatively.

Methods of controlling the driving of such a vibration type actuator include frequency control for changing the frequency of two-phase drive signals and phase difference control for changing the phase difference between the two-phase drive signals. Frequency control is easy to control high-speed drive, and phase difference control is more controllable for low-speed drive than frequency control. Therefore, when feedback-controlling a vibration-type actuator based on speed or position, phase difference control is generally used in a low-speed region such as acceleration at the beginning of movement or deceleration toward stopping.

The vibration type actuator is driven by excitation of vibration such as elliptical motion of the vibrator, as described above. The state of vibration is divided into vibration acting in the contact surface direction between the vibrating body and contact body (hereinafter referred to as push-up vibration) and vibration acting to slide the contact surface between the vibrating body and contact body (hereinafter referred to as feed vibration). divided. When the phase difference is between 0° and 90°, the larger the phase difference, the larger the feed vibration, and the speed of the vibration type actuator increases according to the magnitude of the feed vibration.

In such vibration actuators, it is important to consider the influence of external forces during driving. In the vibration type actuator, when vibration is not accompanied, such as when driving is stopped, the moving body exhibits a high holding force, and can remain at that position even if it receives a certain amount of external force. On the other hand, when there is vibration such as during driving, especially when accelerating at the beginning of movement or decelerating toward stopping, in a state where the phase difference is small and there is not much feed vibration that is the driving force in the driving direction, susceptible to external forces. For example, when an external force is applied in a direction opposite to the driving direction of the vibration type actuator, the actuator may be pushed by the external force at the beginning of movement and cause positional deviation in the opposite direction to the driving direction.

In Patent Document 1, for the purpose of improving the movement of a vibration type actuator, when moving a moving body from a stopped state, an initial phase difference is set to the phase difference between two-phase drive signals, and phase difference control is performed at the initial phase difference. Varying from the phase difference is disclosed. If the external force acts in the opposite direction to the driving direction, it is possible to suppress the positional deviation in the opposite direction at the start of movement by setting the initial phase difference large enough to overcome the external force.

Japanese Unexamined Patent Application Publication No. 2017-123708

On the other hand, when an external force is applied in the forward direction, the target stop position may be greatly overshot (overshoot) due to excessive pushing in the drive direction during deceleration toward a stop. However, the initial phase difference for improving the start of movement in Patent Document 1 increases the driving force in the driving direction. Therefore, when the external force is acting in the forward direction with respect to the driving direction, setting the same initial phase difference as when the external force is acting in the opposite direction with respect to the driving direction will cause overshoot at the target stop position. It can make the shoot bigger. In feedback control, if the overshoot is large, the time required for the moving object to stabilize at the target position (settling time) becomes long.

An object of the present invention is to suppress overshooting with respect to a target position.

In order to achieve the above object, the present invention provides a vibrating body whose vibration is excited by application of two-phase drive signals having a phase difference with each other, and a vibrating body that is in contact with the vibrating body and moves relative to the vibrating body. A vibration type actuator control device for controlling driving of a vibration type actuator having a contact body, wherein an external force applied to the moving body is obtained with respect to a moving direction of the moving body, which is the movable side of the vibrating body and the contact body. a setting means for setting a target position of the moving body; and a control means for controlling the vibrating body, wherein the control means sets the driving direction of the moving body to the target position as the driving in a direction opposite to the driving direction by the driving force based on the target position at least when starting to drive the moving body to the target position when the direction is forward with respect to the direction of the acquired external force It is characterized in that the vibrator is controlled in consideration of force.

According to the present invention, overshoot with respect to the target position can be suppressed.

1A and 1B are a schematic diagram and a block diagram showing the configuration of a lens device; FIG. FIG. 4 is a diagram showing an example of waveforms of two-phase (A-phase and B-phase) drive signals; FIG. 4 is a diagram showing drive characteristics of a vibration type actuator; FIG. 10 is a diagram showing drive characteristics of a vibration actuator when an initial phase difference is set; FIG. 10 is a diagram showing drive characteristics (comparative example) of a vibration type actuator when setting an initial phase difference is not performed; 9 is a flowchart showing initial phase difference setting processing; 9 is a flowchart showing another external force detection process; 1A and 1B are a schematic diagram and a block diagram showing the configuration of a driving device; FIG. 1A and 1B are a schematic diagram and a block diagram showing the configuration of a driving device; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic diagram and a block diagram showing the configuration of a lens device to which a vibratory actuator control device according to a first embodiment of the present invention is applied. This lens device, which is an optical device, includes a lens drive section 100 and a vibration actuator control device for controlling the lens drive section 100 . The control CPU 120, the operation unit 131 and the drive circuit 132 constitute a vibration type actuator control device. Lens driver 100 includes lens 105 .

In the lens drive unit 100 , a fixed lens barrel 101 accommodates an optical system including a lens 105 . A friction member 102 as a contact member is fixed to the inner surface of the fixed lens barrel 101 . The friction material 102 is made of a material that has both a high friction coefficient and friction durability. The vibrating body 103 has a piezoelectric element that is an electro-mechanical energy conversion element and an elastic body to which the piezoelectric element is fixed, and constitutes a vibration type actuator. The vibrating body 103 is in contact with the friction material 102 under pressure due to spring force, magnetic force, or the like. When a two-phase drive signal (frequency signal such as a sine wave signal or a pulse signal) having a phase difference is applied to the piezoelectric element of the vibrating body 103, the contact portion of the elastic body of the vibrating body 103 with the friction material 102 becomes Vibration is excited as an elliptical motion. As a result, the vibrating body 103 as a moving body moves with respect to the friction material 102 , that is, with respect to the fixed lens barrel 101 .

Of the vibrating body and the contacting body, the one on the movable side is referred to as the moving body. In this embodiment, the vibrating body 103 corresponds to the moving body. However, the contact body (friction material 102) and vibrating body 103 move relatively. Therefore, the contact body may be a moving body. For example, the vibrating body 103 may be fixed to the fixed barrel 101 and the friction material 102 may move as a moving body.

A holder 104 is fixed to the vibrating body 103 and holds a lens 105 such as a focus lens and a variable magnification lens. Sleeve 106 is integrally formed with holder 104 . A guide bar 107 is fixed inside the fixed lens barrel 101 . The sleeve 106 is engaged with the guide bar 107 so as to be movable in the direction of the optical axis indicated by the arrow (from the infinite end to the closest end). As the vibrating body 103 moves, the lens 105 held by the holder 104 moves in the optical axis direction. Therefore, the movable direction of the vibrating body 103, which is a moving body, is parallel to the optical axis direction. Here, as shown in FIG. 1, of the optical axis directions, the direction in which the lens 105 advances toward the infinite end is called the first direction, and the direction toward the closest end is called the second direction.

The position of lens 105 is detected by position sensor 108 . An optical encoder or a magnetic encoder can be used as the position sensor 108 . This optical encoder is composed of, for example, an optical scale fixed to a holder 104 and having a light-and-dark pattern, and an optical sensor fixed to a fixed lens barrel 101 for receiving light emitted from a light emitting part and reflected by the optical scale. The magnetic encoder is composed of, for example, a magnetic scale fixed to the holder 104 and having a magnetic pattern, and a magnetoresistive element (MR sensor) fixed to the fixed lens barrel 101 and detecting changes in magnetism from the magnetic scale. be done.

A reference position sensor 109 detects that the lens 105 is positioned at the reference position. As the reference position sensor 109, a photointerrupter having a light emitting portion and a light receiving portion can be used. For example, the holder 104 is provided with a light-shielding portion, and the light-shielding portion enters between the light-emitting portion and the light-receiving portion of the photointerrupter, thereby changing the output of the light-receiving portion from High to Low or from Low to High.

An analog detection signal output from position sensor 108 is input to control CPU 120 . In the control CPU 120, the position detection unit 122 converts the analog detection signal from the position sensor 108 into a digital detection signal, and further indicates the position of the lens 105 (that is, the position of the vibrating body 103 as a moving body) with the digital detection signal. Convert to location data. In the following description, the position represented by this position data is called "detected position". The speed calculation unit 121 converts the amount of change in the detected position obtained at regular intervals into speed. A speed sensor that directly detects the speed of the lens 105 may be provided.

The reference position detector 123 is composed of a buffer circuit or the like with a Schmitt trigger function, detects the signal output from the reference position sensor 109, and calculates and stores the reference position. When obtaining the absolute position of the lens 105, the reference position detection unit 123 detects, for example, a falling edge from High to Low of the photointerrupter of the reference position sensor 109, and stores the position obtained at that time as the reference position. do. After that, the reference position detection unit 123 can obtain the absolute position by calculating the difference between the reference position and the detection positions sequentially obtained by the position detection unit 122 . If the position sensor 108 is composed of a potentiometer and is a sensor capable of detecting an absolute position, the reference position sensor 109 for detecting the reference position and the reference position detector 123 can be omitted.

A target position generator 126 as setting means generates a target position of the lens 105 . When the operation unit 131 is operated, the target position generation unit 126 generates a target position according to the operation. The change of the target position by the target position generator 126 every minute time corresponds to the generation of the speed command.

A subtractor 127 calculates a difference between the detected position (actual position) of the lens 105 output from the position detector 122 and the target position generated by the target position generator 126 to generate a deviation signal. This deviation signal is converted to a control signal for obtaining a drive signal via the control section 128 . A control signal in a vibration-type actuator is a signal including information on the frequency and phase difference of two-phase drive signals. By changing the frequency and phase difference of the two-phase drive signals, the thrust and speed of the vibration actuator are controlled.

The control unit 128 is configured by combining proportional-integral-differential gain devices, and its configuration can be arbitrarily selected according to the control mode. For example, the integral gain device has the function of reducing the deviation that occurs at the time of stopping and enabling the target position to be tracked even when a disturbance such as an impact is applied. A differential gain device is used to avoid the oscillation phenomenon of the vibratory actuator caused by the phase lag. A proportional gain unit is provided for fine-tuning the coefficient conversion and the responsiveness and stability of the vibration type actuator.

The control unit 128 also determines whether or not the detected position of the lens 105 output from the position detection unit 122 has reached the target position generated by the target position generation unit 126 . When it is determined that the detected position has reached the target position, the vibration of the vibrating body 103 is stopped, or the feedback control is continued so as to stay at the target position.

The initial phase difference setting section 124 sets an initial phase difference. The initial phase difference setting unit 124 is used for the purpose of adding the phase difference to the signal containing information on the frequency and phase difference of the two-phase driving signals calculated by the control unit 128 . The initial phase difference setting value is determined based on the information acquired by the external force detection unit 125 . The detection of the external force by the external force detection unit 125 is performed, for example, by acquiring the output of the external force sensor 110 attached to the lens device.

Here, in the present embodiment, it is defined that the external force acting on the lens driving section 100 is gravity. When the optical axis direction of the lens driving unit 100 is tilted with respect to the horizontal, the mass of the lens 105, the holder 104, and the sleeve 106 acts on the vibration type actuator as a self-weight load under the influence of gravity. The self-weight load changes according to the tilt angle of the lens driving section 100, and the self-weight load becomes maximum when the optical axis direction of the lens driving section 100 is oriented in the vertical direction.

As the external force sensor 110, various commonly used sensors can be applied as long as they detect the tilt of the lens drive unit 100 in the optical axis direction. Known sensors for detecting the inclination/posture of such an object include an acceleration sensor for detecting gravitational acceleration, a direction sensor for detecting geomagnetism, and a gyro sensor for detecting rotation angle and angular velocity.

The lens driving unit 100 may be used in a dynamic environment other than gravitational acceleration (a state in which it is always moving while accelerating or decelerating), and it is also necessary to reset accumulated errors that tend to occur in the gyro sensor. For these reasons, the external force sensor 110 may be a combination of an acceleration sensor and a gyro sensor. A combination of sensors can be selected as appropriate, and in such a case, the external force sensor 110 means a sensor including a plurality of sensors. Also, if similar information can be obtained, the external force sensor 110 does not have to be installed in the lens device, and the configuration can be appropriately selected, such as being installed in the imaging device side to which the lens device is attached.

The external force detection unit 125 incorporates in advance the relationship between the tilt angle and the self-weight load generated at the tilt angle as a table or an approximation function, and based on the tilt angle obtained from the external force sensor 110, Determine dead weight load. The initial phase difference setting unit 124 prestores the relationship between the external force (self-weight load) and the initial phase difference required according to the external force as a table or an approximation function, and the external force ( The initial phase difference is determined based on the dead weight load).

Note that the initial phase difference setting unit 124 may directly calculate the initial phase difference from the tilt angle without performing the external force calculation. In that case, the external force detection unit 125 passes the tilt angle as it is to the initial phase difference setting unit 124, and the initial phase difference setting unit 124 determines the initial phase difference based on the built-in relation between the tilt angle and the initial phase difference. do. The process of determining the initial phase difference from the tilt angle (that is, the external force (self-weight load)) will be described later.

The adder 129 adds the initial phase difference to the phase difference among the signals containing information on the frequency and phase difference of the two-phase drive signals calculated by the control unit 128 . Vibration-type actuators have a speed threshold for the phase difference. From 0° to the threshold, the speed increases as the phase difference increases, but when the threshold is exceeded, the speed decreases. Therefore, if the added phase difference exceeds the threshold, the adder 129 may reset the phase difference to the threshold. Also, if a margin is taken with respect to the threshold value (eg, 120°) and the phase difference (eg, 90°) below the threshold value is exceeded, the adder 129 performs processing to reset the phase difference to the above-described phase difference (90°). You may

The drive signal generator 130 uses the control signal calculated by the controller 128 and the initial phase difference set by the initial phase difference setting unit 124 to generate two-phase drive signals while controlling their frequency and phase difference. and output to the drive circuit 132 . The drive circuit 132 amplifies the drive signal from the drive signal generator 130 and applies it to (the piezoelectric element of) the vibrator 103 . As a result, vibration is excited in the vibrating body 103 and the vibrating body 103 moves together with the lens 105 .

FIG. 2 is a diagram showing examples of waveforms of two-phase (A-phase and B-phase) drive signals generated by the drive signal generator 130 . As shown in the drawing, the "phase difference" between the two-phase drive signals means the amount of phase shift between these drive signals. In addition, as shown in FIG. 2(a), the phase difference in the case where the A phase precedes the B phase and is driven in the first direction is defined as a "positive phase difference". ), the phase difference when the B phase precedes the A phase and is driven in the second direction is defined as a “negative phase difference”.

FIG. 3 is a diagram showing the drive characteristics of the vibration type actuator when the lens device is arranged vertically so that the infinite end side faces upward, and the moving body is driven in the first direction (that is, upward). In the example shown in FIG. 3, the set value of the initial phase difference is zero, or the initial phase difference is not added.

The vibration type actuator is feedback controlled to drive at a certain constant speed. FIG. 3 shows the relationship between the generated target position, the actual detected position, and the phase difference. In the feedback control, the control unit 128 adjusts the manipulated variable of the phase difference in the two-phase drive signals (hereinafter referred to as the phase difference manipulated variable) based on the deviation between the current position (detected position) of the moving body and the target position. decide. The phase difference operation amount is the amount of phase difference for canceling the deviation when the position of the moving body is the object of control. In the adder 129, the initial phase difference is added to the phase difference manipulated variable, so that the drive signal generation unit 130 generates a two-phase drive signal when starting to drive the moving body to the target position. be.

At the start of movement of the moving object, the deviation between the target position and the detected position starts from a state of zero, so the manipulated variable of the phase difference (phase difference manipulated variable) calculated based on the deviation also starts near zero. . From immediately after the start of movement to control time A, the phase difference is small and there is not much feed vibration, which is the driving force in the driving direction. downward).

As the deviation increases due to the positional shift, the phase difference operation amount also increases, and when the phase difference reaches the phase difference u, the moving body starts moving in the first driving direction (upward). Due to the change in the deviation due to the start of movement, the phase difference is between the phase differences t and s during the control times B to C, and the vibration type actuator stays at a substantially constant position with respect to this phase difference. After the control time C, stable driving with the phase difference t is continued.

Vibration-type actuators require a large amount of phase difference operation because they require the greatest propulsion force at the beginning of movement in the presence of a load. , the phase difference operation amount becomes small. This is considered to be close to the relationship between so-called static friction and dynamic friction. In the vibration-type actuator device according to the present embodiment, the main areas that receive relative friction are the combination of friction material 102 and vibrating body 103 and the combination of sleeve 106 and guide bar 107 .

A vibration type actuator can start moving in a desired driving direction by generating a driving force (phase difference) greater than the resultant force of its own weight load and static friction force. When the self-weight load is greater than the static frictional force, positional deviation occurs as shown in the figure, but no positional deviation occurs when the static frictional force is greater than the self-weight load. Even if there is no misalignment, the vibration type actuator starts moving in the driving direction by generating a driving force (phase difference) greater than the combined force of the self-weight load and the static friction force, and then shifts to dynamic friction. Phase difference operation amount becomes small.

4(a) and 4(b) are diagrams showing drive characteristics of the vibration type actuator when the initial phase difference is set in this embodiment. FIGS. 5A and 5B are diagrams showing drive characteristics (comparative example) of the vibration type actuator when the initial phase difference is not set. In both examples of FIGS. 4 and 5, the lens device is arranged so that the infinite end side faces vertically upward. FIGS. 4(a) and 5(a) show the relationship between the position and the phase difference when feedback control driving is performed with the driving direction being the first direction (upper vertical direction). FIGS. 4(b) and 5(b) show the relationship between the position and the phase difference when feedback control driving is performed with the driving direction being the second direction (vertically downward).

The influence of the positional deviation due to the self-weight load becomes relatively more pronounced as the drive amount becomes smaller. In FIGS. 4 and 5, the drive amount Δa is set to a very small value of about several μm. In FIGS. 4 and 5, the control time graph scale and the phase difference graph scale are all common, and the position graph scale is relatively compared with the magnitude of the drive amount Δa.

As explained in FIG. 3, the phase difference for overcoming the resultant force of the self-weight load and the static friction force in the vertical upward drive is u, and the phase difference for stable driving under the self-weight load and dynamic friction is t. be. Therefore, if at least the phase difference is s, the moving body can maintain its position (balance) against the load of its own weight. Using the phase difference s that does not cause positional deviation as a reference, a positive phase difference may be added to move it further vertically upward from the equilibrium position, and a negative phase difference may be added to move it vertically downward. Therefore, in the present embodiment, the phase difference s is set as the initial phase difference, and the initial phase difference is added to the positive phase difference and the negative phase difference calculated by the control unit 128 according to the driving direction.

Since the relationship between the phase differences s, t, and u shows some changes depending on the temperature environment and driving speed, the phase difference set as described above may not be the optimum value depending on the conditions. However, it has a sufficient effect of suppressing positional deviation.

Control CPU 120 gives a positive phase difference when moving the moving body in the first direction (vertically upward). Based on the results shown in FIG. 3, the phase difference s is given as the initial phase difference in FIG. 4(a). In FIG. 4(a), a large positional deviation at the start of movement as seen in FIG. 5(a) is suppressed. Therefore, driving accuracy is improved and settling time is reduced.

Next, consider the case of moving the moving body in the second direction (vertically downward). Originally, a negative phase difference should be given to move in the second direction. However, under the drive condition that gives a negative phase difference, as shown in FIG. 5B, a vertical downward positional shift (overshoot) that greatly exceeds the drive amount Δa occurs at the start of movement. In such a case, as shown in FIG. 4B, a positive phase difference should be given to the initial phase difference.

In FIG. 4B, the phase difference s is given as the initial phase difference. By adding the positive phase difference as the initial phase difference, the self-weight load and the vertical upward propulsive force are offset, thereby enabling stable driving with suppressed positional deviation. As a result, in FIG. 4(b), the overshoot greatly exceeding the target position as seen in FIG. 5(b) is suppressed. Therefore, driving accuracy is improved and settling time is reduced.

FIG. 6 is a flowchart showing initial phase difference setting processing. The functions of each functional block (FIG. 1) in the control CPU 120 as control means are realized by the cooperation of a CPU, ROM, RAM, timer, etc. (not shown). The processing shown in FIG. 6 is implemented by expanding a program stored in the ROM of the control CPU 120 into the RAM and executing the program. This process is started upon receiving a drive command. This processing assumes a system in which the moving body is displaced due to gravity.

First, in step S201, control CPU 120 executes external force detection processing. That is, the external force detection unit 125 as an acquisition unit analyzes the output regarding the tilt angle from the external force sensor 110 and calculates the tilt angle. The external force detection unit 125 further acquires the external force applied to the moving body with respect to the movable direction of the moving body from the calculated tilt angle. That is, the external force detection unit 125 calculates the magnitude and direction of the self-weight load, and transfers the result to the initial phase difference setting unit 124 . It should be noted that the external force detection unit 125 may directly transfer the tilt angle to the initial phase difference setting unit 124 without calculating the self-weight load.

In step S202, control CPU 120 determines the driving direction. This is performed with reference to the driving direction indicated by the operation unit 131 . That is, the driving direction of the moving body to the target position set by the target position generation unit 126 is determined according to the operation of the operation unit 131 . In step S203, control CPU 120 determines whether or not the driving direction and the direction (orientation) of the external force are opposite directions. In other words, the control CPU 120 determines whether or not the driving direction of the moving body to the target position is opposite to the direction of the external force. As a result of the determination, the control CPU 120 executes steps S204 and S205 if the driving direction and the direction of the external force are opposite directions, and if the driving direction and the direction of the external force are forward directions, steps S206, Execute S207.

In step S204, control CPU 120 calculates an initial phase difference required when driving in the direction opposite to the external force. First, the initial phase difference setting unit 124 acquires and stores in advance the correspondence relationship between the tilt angle and the phase difference that does not shift at the tilt angle. This correspondence relationship is stored in advance as a table or function according to the tilt angle, in the same way that the phase difference that does not cause positional deviation when the tilt angle is in the vertical direction (that is, 90 degrees) is determined to be s in FIG. It is The control CPU 120 (initial phase difference setting unit 124 ) determines the initial phase difference from the tilt angle (external force) information received from the external force detection unit 125 with reference to the correspondence relationship.

In step S205, control CPU 120 determines the polarity of the initial phase difference according to the driving direction. Here, since the direction of the external force is the direction opposite to the driving direction, it is necessary to suppress positional deviation at the start of movement. First, the movable body can be driven in the first direction with a positive phase difference. Therefore, when the driving direction is the first direction, the control CPU 120 (initial phase difference setting unit 124) sets the initial phase difference to a positive phase difference in order to assist the movement in the driving direction against the external force. Determined as Therefore, the initial phase difference in this case is set to have the same polarity as the phase difference manipulated variable.

On the other hand, the movable body can be driven in the second direction with a negative phase difference. Therefore, when the driving direction is the second direction, the control CPU 120 (initial phase difference setting unit 124) sets the initial phase difference to a negative phase difference in order to assist the movement in the driving direction against the external force. Determined as Therefore, the initial phase difference in this case is also set to have the same polarity as the phase difference manipulated variable.

In step S206, control CPU 120 calculates an initial phase difference required for forward driving against an external force. The control CPU 120 (initial phase difference setting unit 124 ) determines the initial phase difference from the tilt angle (external force) information received from the external force detection unit 125 with reference to the correspondence relationship.

In step S207, control CPU 120 determines the polarity of the initial phase difference according to the driving direction. Here, since the direction of the external force and the driving direction are forward, it is necessary to suppress overshoot at the target position. First, the movable body can be driven in the first direction with a positive phase difference. Therefore, when the driving direction is the first direction, the control CPU 120 (initial phase difference setting unit 124) determines the initial phase difference as a negative phase difference in order to resist being pushed in the driving direction by an external force. . Therefore, the initial phase difference in this case is set to have a polarity opposite to the polarity of the phase difference manipulated variable.

On the other hand, the movable body can be driven in the second direction with a negative phase difference. Therefore, when the driving direction is the second direction, the control CPU 120 (initial phase difference setting unit 124) determines the initial phase difference as a positive phase difference in order to resist being pushed in the driving direction by an external force. . Therefore, the initial phase difference in this case is also set to have a polarity opposite to the polarity of the phase difference manipulated variable. After steps S205 and S207, the process shown in FIG. 6 ends.

According to the present embodiment, when the driving direction is the forward direction with respect to the direction of the external force, control CPU 120 sets the phase difference manipulated variable to an initial phase difference having a polarity opposite to the polarity of the phase difference manipulated variable. Add That is, the control CPU 120 substantially controls the vibrating body 103 by adding a driving force based on the target position to a driving force in a direction opposite to the driving direction at least when starting to drive the moving body to the target position. do. As a result, when the moving body is driven in the forward direction against an external force, overshooting of the moving body with respect to the target position can be suppressed. In addition, it is possible to improve controllability and avoid an increase in settling time.

On the other hand, when the drive direction is opposite to the direction of the external force, control CPU 120 adds an initial phase difference having the same polarity as the phase difference manipulated variable to the phase difference manipulated variable. In other words, the control CPU 120 substantially, at least when starting to drive the moving body to the target position, drives the vibrating body 103 by adding the forward driving force to the driving direction to the driving force based on the target position. Control. As a result, it is possible to prevent the moving body from being displaced in the opposite direction when it is driven in the opposite direction to the external force. In addition, it is possible to improve controllability and avoid an increase in settling time.

In particular, when the external force is gravity, it is possible to provide a lens device that reduces deterioration in controllability due to the influence of gravity.

In addition, the initial phase difference is set based on a phase difference that allows the moving body to maintain its positional balance against external forces under dynamic friction in a driven state, thereby shortening the settling time. can do. It should be noted that the magnitude of the initial phase difference value to be added to the phase difference manipulated variable does not necessarily have to be set according to the above criteria. For example, even if the initial phase difference is set to a value that does not meet the above criteria, it is effective in improving controllability compared to control that does not add the initial phase difference.

Note that in the external force detection process in step S201, the magnitude and direction of the external force are obtained based on the output of the external force sensor 110. FIG. However, it is not limited to this, and it is also possible to use, for example, a method of referring to the immediately preceding drive characteristic as in the modification shown in FIG.

FIG. 7 is a flowchart showing another external force detection process. If this process is applied, this process is performed in step S102 of FIG. This processing assumes that the tilt of the lens device is substantially constant.

In steps S301 to S303, the control CPU 120 refers to the drive characteristic information at the time of the previous (previous) drive command. That is, the control CPU 120 acquires the driving direction, the magnitude of the positional deviation at the start of movement, and the magnitude of the overshoot during the immediately preceding driving as information on the driving characteristics at the time of the immediately preceding driving command. In step S304, control CPU 120 calculates the tilt angle (external force) related to the current drive command based on the acquired information.

For example, when the vibration type actuator is moved upward with the lens apparatus tilted, positional deviation at the start of movement occurs downward, and the amount of positional deviation varies depending on the tilt angle. Also, when the vibration type actuator is moved downward, positional deviation in the direction opposite to the start of movement is not detected, but overshoot at the target position is detected according to the tilt angle. Therefore, the inclination angle (external force) can be calculated by referring to the immediately preceding driving characteristics and referring to the relationship between the driving direction, the amount of positional deviation at the start of movement, and the amount of overshoot at the target position.

In the processing shown in FIG. 7, relatively accurate detection is possible if the inclination of the lens device is substantially constant. However, if the tilt of the lens device in the current drive greatly changes from the previous drive, there is a possibility that the calculated tilt angle and the actual tilt angle will deviate. In order to solve this problem, for example, it is conceivable to perform test drive for external force detection prior to the drive command. In this test drive, for example, the vibratory actuator is operated with a controllable gap time that is non-intrusive to the user. Before and after the test drive, the moving body is always returned to the original position by the reciprocating drive so that the position of the vibration type actuator does not change. A configuration may be adopted in which an external force is detected using the drive characteristics in this test drive, and an initial phase difference is set. Moreover, the external force detection by the external force sensor and the external force detection using the immediately preceding drive characteristic may be used together.

(Second embodiment)
8A and 8B are a schematic diagram and a block diagram showing the configuration of a driving device to which a vibration type actuator control device according to a second embodiment of the present invention is applied. The basic configuration of the vibration-type actuator device according to the present embodiment is the same as that of the first embodiment, and it is assumed that the lens driving section 100 is replaced with the driving section 200 .

In this embodiment, a system in which a biasing force is applied by a spring 203 as a biasing member is assumed as a constant external force other than gravity. As such a system, for example, a system in which the reciprocating motion of the piston is spring-biased in the expansion/contraction direction can be precisely controlled by a direct-acting actuator. Alternatively, a system in which the gripping operation of the chuck unit is spring-biased in the gripping direction is driven and controlled by a linear actuator, or a cylinder structure that is spring-biased in one direction, such as a pressure reducing valve, is used as a linear actuator. A system in which the drive is controlled by

FIG. 8 shows a simple configuration in which a spring 203 is connected between a housing 201 and a driven portion 202 as an example of receiving a spring force. The driven part 202 is held by the holder 104 . Since the spring 203 expands and contracts when the driven portion 202 is moved in the first direction and the second direction by the vibration type actuator, the spring force acts on the driven portion 202 as an external force. Therefore, the biasing force from the spring 203 acts on the vibrating body 103 as a moving body via the driven part 202 .

The acting external force is determined by the elastic modulus and expansion/contraction amount of the spring 203 . Therefore, for example, the external force sensor 110 detects the amount of expansion and contraction of the spring 203, and the external force detection unit 125 calculates the spring force from the amount of contraction of the spring 203 and the elastic modulus of the pre-built spring. The initial phase difference setting unit 124 contains in advance the relationship between the spring force and the phase difference that resists the spring force. The initial phase difference setting section 124 sets the required initial phase difference based on the spring force sent from the external force detection section 125 . Unlike gravity, the magnitude of the spring force as an external force changes according to the amount of expansion and contraction, but the spring force applied at the start of movement and the spring force applied at the target position can be resisted. The relationship with the phase difference should be acquired in advance.

Spring force is defined as a linear function with respect to the amount of expansion and contraction. Therefore, it is possible to adopt a method of changing the initial phase difference according to the spring force. For example, it is possible to adopt a method of linearly changing the initial phase difference according to the drive position, from the value required at the start of movement to the value required to reach the target position.

If the driving direction is opposite to the external force (spring force), it is necessary to suppress positional deviation at the start of movement. Therefore, in order to assist the movement in the driving direction against the external force, an initial phase difference having the same polarity as the polarity of the phase difference required in the driving direction is set. On the other hand, if the drive direction is in the same direction as the external force (spring force), it is necessary to suppress overshoot at the target position. Therefore, an initial phase difference having a polarity opposite to the polarity of the phase difference required in the driving direction is set so as to resist the urging in the driving direction by an external force.

According to the present embodiment, when driving in the forward direction with respect to an external force, it is possible to achieve the same effect as the first embodiment in terms of suppressing overshoot of the moving body with respect to the target position. In addition, when driving in the opposite direction to the external force, the same effect as in the first embodiment can be obtained in terms of suppressing the displacement of the moving body in the opposite direction. In particular, even when a constant external force other than gravity acts, it is possible to improve controllability and avoid an increase in settling time.

Note that the present embodiment and the first embodiment may be combined. That is, when a self-weight load (gravitational force) due to a difference in posture is applied in addition to the spring force, an initial phase difference required for the resultant force of these external forces may be set.

(Third Embodiment)
FIG. 9 is a schematic diagram and a block diagram showing the configuration of a driving device to which a vibration type actuator control device according to a third embodiment of the invention is applied. The basic configuration of the vibration type actuator device according to the present embodiment is the same as that of the first embodiment, and it is assumed that the lens driving section 100 is replaced with the driving section 300 .

This embodiment assumes a system to which a regular or sudden external force is applied. As such a system, a case is assumed in which the driven part 302 driven by a linear actuator is pushed by an external force, or an object collides with the driven part 302 .

FIG. 9 shows a simple configuration in which the load body 303 applies force to the driven portion 302 as an example of receiving an external force. The driven part 302 is held by the holder 104 . The load body 303 applies an external force to the driven portion 302 directly or indirectly via another member. The vibration actuator drives the driven part 302 against the force. The force applied by the load body 303 may be constant or indefinite, and may be continuous or discontinuous. If the force of the load body 303 is regular, it is assumed that the driven part 302 is driven against the acting force. A crash is assumed.

The external force is obtained, for example, from the output (amount of strain) of an external force sensor 110 installed on the mobile object. As the external force sensor 110 that directly detects the external force acting on the driven part 302 from the load body 303, for example, a strain gauge type or capacitance type force sensor can be used. If the direction of the external force is in only one axis, a known measurement unit such as a load cell using strain gauges may be used. The external force detection unit 125 can detect the external force by calibrating the output of the strain gauge in a form suitable for the system.

Also, the external force when the object collides can be estimated from the detection result of the strain gauge. Alternatively, the external force sensor 110 is an acceleration sensor, which detects the acceleration when the driven part 302 shifts due to the collision, and from this acceleration and the weight of the driven part 302, it is possible to estimate the external force at the time of the collision. be. Alternatively, an external force estimation observer that estimates an external force from the load torque state and the acceleration state of the vibration actuator may be employed. As described above, external force sensor 110 and external force detection unit 125 may be configured in accordance with various external force detection methods.

The initial phase difference setting unit 124 incorporates in advance the relationship between the external force and the phase difference for resisting the magnitude of the external force. The initial phase difference setting unit 124 refers to the above relationship, and sets or resets the initial phase difference based on the external force information sent from the external force detection unit 125, regardless of whether the movement has started or is in the middle of driving. Make settings.

For example, if the driving direction is the opposite direction to the external force, it is necessary to suppress positional deviation at the start of movement. Therefore, in order to assist the movement in the driving direction against the external force, an initial phase difference having the same polarity as the polarity of the phase difference required in the driving direction is set. On the other hand, if the drive direction is in the same direction as the external force, it is necessary to suppress overshoot at the target position. Therefore, an initial phase difference having a polarity opposite to the polarity of the phase difference required in the driving direction is set so as to resist being pushed in the driving direction by an external force.

According to the present embodiment, when driving in the forward direction with respect to an external force, it is possible to achieve the same effect as the first embodiment in terms of suppressing overshoot of the moving body with respect to the target position. In addition, when driving in the opposite direction to the external force, the same effect as in the first embodiment can be obtained in terms of suppressing the displacement of the moving body in the opposite direction. In particular, even when a sudden external force acts, it is possible to improve controllability and avoid an increase in settling time.

Note that this embodiment may be combined with either or both of the first embodiment and the second embodiment. For example, when a self-weight load (gravitational force) or a spring force due to a difference in posture is applied in addition to a sudden external force, an initial phase difference required for the resultant force of these external forces may be set.

In each of the above-described embodiments, an example in which the vibration type actuator control device of the present invention is applied to a lens device and a drive device for photographing has been described. However, the driven member that moves integrally with the moving body is not limited to the lens, and the driven member may be an imaging device of an imaging device or an imaging unit including a lens and an imaging device. In other words, the present invention can be applied to various other devices such as a driving device having a driven member driven by a vibration type actuator.

Although the present invention has been described in detail based on its preferred embodiments, the present invention is not limited to these specific embodiments, and various forms without departing from the gist of the present invention can be applied to the present invention. included. Some of the above embodiments may be combined as appropriate.

102 Friction Material 103 Vibrating Body 120 Control CPU
125 external force detector 126 target position generator

Claims (11)

Driving a vibration-type actuator having a vibrating body whose vibration is excited by application of two-phase drive signals having a phase difference with each other, and a contact body that contacts the vibrating body and moves relative to the vibrating body A vibration type actuator control device for controlling
Acquisition means for acquiring an external force applied to the moving body with respect to a moving direction of the moving body, which is the movable side of the vibrating body and the contact body;
setting means for setting a target position of the moving object;
and a control means for controlling the vibrating body,
When the driving direction of the moving body to the target position is forward with respect to the direction of the acquired external force, the control means controls at least when starting to drive the moving body to the target position. A vibration type actuator control device, wherein the vibrating body is controlled by adding a driving force in a direction opposite to the driving direction to a driving force based on the target position. When the driving direction is opposite to the direction of the external force, the control means controls the driving force based on the target position at least when starting to drive the moving body to the target position. 2. The vibrating actuator control device according to claim 1, wherein the vibrator is controlled by adding a driving force in a forward direction to the direction. The control means determines a phase difference manipulated variable based on the deviation between the current position of the moving body and the target position, determines an initial phase difference based on the magnitude and direction of the external force, and determines the position of the moving body. 3. The drive signal according to claim 1, wherein the drive signal for starting the drive of the moving body to the target position is generated by adding the initial phase difference to the phase difference manipulated variable. Vibration type actuator controller. The control means adds the initial phase difference having a polarity opposite to the polarity of the phase difference manipulated variable to the phase difference manipulated variable when the driving direction is forward with respect to the direction of the external force. 4. The vibration type actuator control device according to claim 3, wherein: When the driving direction is opposite to the direction of the external force, the control means adds the initial phase difference having the same polarity as the phase difference manipulated variable to the phase difference manipulated variable. 5. The vibration type actuator control device according to claim 3 or 4, characterized by: The initial phase difference is set based on a phase difference that allows the moving body to maintain positional equilibrium against the external force under dynamic friction in which the moving body is in a driven state. The vibration type actuator control device according to any one of claims 3 to 5. 7. The vibration type actuator control device according to any one of claims 1 to 6, wherein the external force includes gravity. 8. The apparatus according to any one of claims 1 to 7, wherein said external force includes an urging force of an urging member that urges said moving body, and said urging force is obtained from the detected amount of expansion and contraction of said urging member. The vibration type actuator control device according to any one of claims 1 to 3. 8. The vibration type actuator control device according to any one of claims 1 to 7, wherein the external force is acquired from an output of an external force sensor installed on the moving body. a vibrating actuator having a vibrating body whose vibration is excited by application of two-phase drive signals having a phase difference with each other; and a contact body that contacts the vibrating body and moves relative to the vibrating body;
a vibration actuator control device according to any one of claims 1 to 9,
The lens device, wherein the vibration type actuator includes a lens fixed to either the vibrating body or the contact body. a vibrating actuator having a vibrating body whose vibration is excited by application of two-phase drive signals having a phase difference with each other; and a contact body that contacts the vibrating body and moves relative to the vibrating body;
a vibration actuator control device according to any one of claims 1 to 9;
and a driven member that is driven by the vibration type actuator.

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