WO2022270382A1 - Electric linear actuator - Google Patents

Abstract

Provided is an electric linear actuator in which discontinuous stiffness caused on the basis of the gear ratio of a transmission mechanism is taken into consideration to enable driving of an electric motor with high precision. An electric linear actuator comprises: an electric motor (510); a linear motion mechanism (520); a control device (100) that controls a load which is applied to an object by the linear motion mechanism through a linear motion thereof as the electric motor is driven; and a transmission mechanism (580) having a speed changing function wherein a corresponding relationship between the amount of linear motion and the amount of rotation of the electric motor changes at a predetermined load. The control device has: an estimator (130) that estimates a load applied by the linear motion mechanism; a load controller (113) that uses a control gain, by which a deviation or the like between an estimated value and a target value of the load is multiplied, for a control computation, and that, in a state in which the estimated value or the like of the load is not zero, uses, at least at one point, a control gain varying discontinuously with respect to transition of at least one of the estimated value and the target value of the load, to calculate a motor drive amount; and a control gain adjustment unit (115) that adjusts the control gain.

Description

Electric linear actuator Related application

This application claims the priority of Japanese Patent Application No. 2021-103324 filed on June 22, 2021, and is incorporated herein by reference in its entirety.

The present invention relates to a control method for an electric linear motion actuator that converts rotary motion of an electric motor into linear motion.

Electric linear motion actuators have been considered for use in, for example, electric brake devices and electric press devices. 2. Description of the Related Art As a conventional electric brake device, an electric actuator with a speed change function using a planetary roller screw structure included in a planetary rolling element has been proposed, for example, as disclosed in Patent Document 1.

JP 2012-057681 A

In general, in applications such as electric brakes to which an electric linear motion actuator is applied, it is often required to precisely control the actuator. At that time, for example, in the case of applying an electric linear motion actuator with a speed change mechanism as described in Patent Document 1, the drive amount (rotation amount, rotation speed) of the electric motor during driving and the linear motion of the linear motion actuator (i.e. equivalent to the equivalent lead corresponding to the amount of linear motion of the linear motion with respect to the amount of rotation of the electric motor) is in a different state than expected, the controllability and responsiveness deteriorate. Problems can arise.

For example, in the linear motion actuator with a speed change mechanism described in Patent Document 1, the reaction force when the actuator applies a load to an object is a plurality of planetary rollers and a sun roller (or a rotation input shaft) that is a rotation shaft that exists at the center of the planetary rollers. ), the planetary roller rotates in the planetary deceleration structure provided in the planetary roller screw structure, and the planetary carrier and the sun roller that support the plurality of planetary rollers rotate. It has a speed change function that reduces the equivalent lead by producing a planetary deceleration effect that causes a speed difference. In this case, there is a discontinuity in the equivalent lead based on the gear ratio (change ratio of the equivalent lead) in the gear shift function. When the linear motion mechanism is provided with such a speed change function, the linear motion actuator has a relatively large clearance until it comes into contact with an object to which a load is applied, such as the clearance between the friction material and the brake rotor in an electric brake device. Equivalent lead is formed, responsiveness is improved, and after the load is applied, the equivalent lead becomes relatively small, and even a small motor with small output torque can generate a large load, which is preferable. However, a structure that immediately changes the speed of the linear motion mechanism by the speed change function when the load becomes non-zero must achieve the speed change operation with a very small amount of spring force and spring deformation. Due to the circumstances, it is extremely difficult, and in order to construct a stable transmission mechanism, there is a possibility that a structure that shifts gears while a certain amount of load is applied may be required. However, when it is necessary to control a small actuator load, such as when a light brake operation is performed in an electric brake device, it may become difficult to control the actuator load with high precision due to the speed change operation.

In addition, for example, in the shift operation in the structure described in Patent Document 1, due to the nonlinear hysteresis characteristics of the displacement and spring force generated due to friction, for example, the actuator applied load is increased (increased pressure) and decreased. There may be a problem in that the shifts are shifted at different timings in the operation of reducing the pressure.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems of the prior art by taking into consideration the discontinuous stiffness that occurs based on the gear ratio in the transmission mechanism, thereby enabling the electric motor to be driven with high accuracy. Another object is to provide a dynamic actuator.

In order to achieve the above object, an electric linear motion actuator according to the present invention includes:
an electric motor, a linear motion mechanism that converts rotary motion of the electric motor into linear motion, a control device that drives the electric motor and controls the load that the linear motion mechanism applies to an object due to the linear motion; a speed change mechanism having a speed change function in which the correspondence relationship between the amount of linear motion of the linear motion and the amount of rotation of the electric motor changes with respect to a predetermined load;
The control device is
an estimator for estimating the load applied by the linear motion mechanism;
In the process of deriving the drive amount of the electric motor, at least one or more of a deviation between the estimated value of the load and the target value of the load, an integral value of the deviation, and a differential value of the deviation The control gain to be multiplied is used for control calculation, and in a state in which at least one of the estimated value of the load and the target value is not zero, the estimated value of the load and the target value at least at one or more locations. a load controller that calculates a motor drive amount using a control gain that changes discontinuously with respect to the transition of at least one of
a control gain adjustment unit that adjusts the control gain used in the load controller according to the load condition;
have

According to the above configuration, the electric linear motion actuator according to the present invention sets the control gain in consideration of the discontinuous stiffness that occurs based on the gear ratio in the transmission mechanism under load conditions that cause gear shifting. Therefore, it is possible to drive the electric motor with high accuracy.

In the above configuration, the speed change mechanism compares a first equivalent lead state in which the amount of linear motion has a predetermined correlation with the amount of rotation of the electric motor, and the first equivalent lead state. a second equivalent lead state in which the amount of direct motion with respect to the amount of rotation has a small correlation,
In the process of increasing the load applied by the linear motion mechanism, the shift function switches from the first equivalent lead state to the second equivalent lead state when the first shift load, which is the predetermined load, is exceeded. , in the process of reducing the load applied by the linear motion mechanism, when the load falls below the second shift load, which is the predetermined load different from the first shift load, the second equivalent lead state changes to the first shift load. has a non-linearity that switches to the equivalent lead state,
With respect to the control gain, the control gain on the side of the smaller load from the first discontinuity point where the transition of the control gain with respect to the transition of the load is discontinuous is greater than the control gain on the side of the larger load than the first discontinuity point. including the first point of discontinuity that becomes smaller;
The transmission function having non-linearity and the control gain of the transmission mechanism may meet any one of the following conditions i) and ii).
i) the first shift load of the shift function is greater than the second shift load, and the first discontinuity point of the control gain is greater than the second shift load to the first shift load; close.
ii) said second shift load of said shift function is greater than said first shift load, and said first discontinuity point of said control gain is greater than said first shift load to said second shift load; close.
As a result, in a load region in which it is uncertain whether or not gear shifting will occur, if the motor is driven on the assumption that the equivalent lead is small despite the fact that the equivalent lead is large, the actuator load may change significantly, resulting in unstable operation. Therefore, the above-described unstable actuator operation can be suppressed by operating the area where the shift is unstable assuming that at least the equivalent lead is large.

In the above configuration, the linear motion mechanism is
a rotation input member, a planetary carrier rotatably supported concentrically with the rotation input member, a planetary rolling element rotatably supported by the planetary carrier;
The planetary rolling element does not rotate due to the elastic force, and the rotation input member and the planetary carrier are synchronously rotated. and an elastic member that rotates the planetary rolling element and causes a difference in the amount of rotation between the rotation input member and the planetary carrier,
In the process in which the load applied by the linear motion mechanism increases, the elastic member completes deformation when a predetermined first deformation load is exceeded, and in the process in which the load applied by the linear motion mechanism decreases. has a non-linear deformation characteristic in which the elastic member begins to deform when falling below a second deformation load different from the first deformation load,
With respect to the control gain, the control gain on the side of the smaller load from the second discontinuity point where the transition of the control gain with respect to the transition of the load is discontinuous is greater than the control gain on the side of the larger load than the second discontinuity point. including the growing second point of discontinuity;
The deformation characteristic and the control gain of the elastic member of the linear motion mechanism may meet either condition i) or ii) below.
i) the first deformation load of the elastic member is greater than the second deformation load, and the second discontinuity of the control gain is greater than the first deformation load to the second deformation load; close.
ii) the second deformation load of the elastic member is greater than the first deformation load, and the second discontinuity point of the control gain is closer to the first deformation load than the second deformation load; close.
As a result, in a load region in which it is uncertain whether or not spring deformation will occur in a shift function using a spring elastic member, if the motor is driven on the assumption that the spring will deform even though the spring does not deform, the actuator load will increase. Since the deformation of the spring may change and become unstable, the unstable actuator operation can be suppressed by operating at least the region where the deformation of the spring is unstable as if the spring is not deformed.

In the above configuration, the control gain adjustment unit includes: a control gain during pressure increase, which is the control gain during pressure increase when the load increases; a control gain during pressure decrease, which is the control gain during pressure decrease when the load decreases; a control gain switching unit that determines which of the pressure increase control gain and the pressure decrease control gain to refer to,
The control gain switching unit refers at least to the control gain of the pressure increasing control gain when the motor is rotating on the pressure increasing side based on transition of the motor angle, and when the motor is rotating on the pressure decreasing side, the pressure reducing control gain. The control gain may be switched so as to refer to the control gain of the time control gain.
As a result, for example, the first and second shift loads and the first and second deformation loads, such as the first and second deformation loads, are linear motion mechanisms having nonlinear characteristics that differ between when the pressure is increased and when the pressure is decreased. and the second shift load, or the load region between the first and second deformation loads, when the pressure is stably increased, the characteristics at the time of pressure increase are obtained, and when the pressure is decreased, the characteristics at the time of pressure reduction are obtained. When employing a driving mechanism, the actuator can be operated with higher accuracy.

In the above configuration, the control gain adjustment unit adjusts the first control gain, which is the control gain of the electric motor when an equivalent lead corresponding to the amount of linear motion of the linear motion with respect to the amount of rotation of the electric motor is large, and the equivalent A second control gain that is the control gain when the lead is small and the elastic member deforms, and a third control gain that is the control gain when the equivalent lead is small and the elastic member reaches a deformation limit. and a control gain switching unit that switches to any one of the first to third control gains for reference,
The electric linear motion actuator further comprises:
a change gradient calculation unit that derives a gradient of change of one of the motor angle and the estimated load with respect to the change of the other;
storing the gradient of change derived by the gradient-of-change computing unit; comparing the stored gradient of change with the gradient of change newly derived by the gradient-of-change computing unit after storing; a change gradient comparison unit that determines that a control gain discontinuity exists when the gradient changes,
The control gain switching unit uses the first to third control gains, and if there are a plurality of discontinuous points, at least one of the plurality of discontinuous points determined by the change gradient comparing unit according to
When it is determined that the point of discontinuity has occurred when the load changes in the direction of increasing pressure while referring to the first control gain, referring to the second control gain,
In the state of referring to the second control gain, when the pressure is changed in the direction of pressure increase, when it is determined that the discontinuity has occurred, the third control gain is referred to, and when the pressure changes in the direction of pressure reduction, referring to the first control gain when it is determined that the discontinuity point has occurred;
The second control gain may be referred to when it is determined that the point of discontinuity has occurred when the pressure changes in the direction of pressure reduction while the third control gain is being referred to.
As a result, for example, the first and second shift loads and the first and second deformation loads, such as the first and second deformation loads, are linear motion mechanisms having nonlinear characteristics that differ between when the pressure is increased and when the pressure is decreased. By adopting an appropriate control gain even in a region where the actuator stiffness is unstable, such as the load region between and the second shift load, or the load region between the first and second deformation loads, The actuator can be operated with high precision.

In the above configuration, the control device
an estimator for estimating the rotation angle of the electric motor;
A rotation amount of the electric motor and the estimated load when a change in the load of a predetermined amount occurs in a range including at least the load corresponding to the discontinuity point of the control gain stored in advance. Having a stiffness parameter storage unit that stores a change history,
Further, the control device
a nonlinear stiffness estimating unit that estimates a point of discontinuity in the control gain from the angle of the electric motor and the change history of the estimated load, and updates the control gain based on the estimated point of discontinuity; You may
As a result, regarding characteristic fluctuations in the control gain that can occur due to, for example, changes in the contact state of each component of the electric linear motion actuator and wear of parts, at least By reflecting the result of estimating the change in the discontinuous point in the control gain, it is possible to control the electric linear motion actuator with higher accuracy at least from the next operation onward (updating and estimating from the log information).

In the above configuration, the control device
an estimator for estimating the rotation angle of the electric motor;
estimating and storing an amount of change in either one of the load and the amount of rotation when a predetermined amount of change in the load or the amount of rotation of the electric motor occurs, and
Further, the control device
The stored amount of change is compared with the amount of change newly estimated after the storage, and if the amount of change changes more than a predetermined amount, the angle and load of the electric motor at the control gain are determined. may be determined to have occurred, and the control gain may be updated based on the determined discontinuity point.
As a result, regarding characteristic fluctuations in the control gain that can occur due to, for example, changes in the contact state of each component of the electric linear motion actuator and wear of parts, at least By reflecting the result of estimating the change in the discontinuous point in the control gain, it becomes possible to control the electric linear motion actuator with higher accuracy at least from the next operation onward (real-time estimation).

Any combination of at least two configurations disclosed in the claims and/or the specification and/or the drawings is included in the present invention. In particular, any combination of two or more of each claim is included in the invention.

The present invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are for illustration and description only and should not be used to define the scope of the invention. The scope of the invention is defined by the appended claims. In the accompanying drawings, the same reference numerals in multiple drawings indicate the same or corresponding parts.

1 is a block diagram showing a schematic configuration of an electric linear motion actuator according to one embodiment of the present invention; FIG. FIG. 4 is a block diagram showing a schematic configuration of an electric linear motion actuator according to another embodiment of the present invention; FIG. 2 is a schematic diagram of a linear motion mechanism having a transmission mechanism in each of the electric linear motion actuators; FIG. 2 is a block diagram of an example of a load controller included in a control device in each electric linear motion actuator; FIG. 4 is a block diagram of another example of a load controller included in the control device in each of the electric linear motion actuators; FIG. 4 is an example of a characteristic diagram for explaining control gains of a control gain adjusting section included in the load controller; FIG. 11 is another example of a characteristic diagram for explaining the control gain of the control gain adjusting section included in the load controller; FIG. FIG. 13 is still another example of a characteristic diagram for explaining the control gain of the control gain adjustment section included in the load controller; FIG. FIG. 13 is still another example of a characteristic diagram for explaining the control gain of the control gain adjustment section included in the load controller; FIG. FIG. 13 is still another example of a characteristic diagram for explaining the control gain of the control gain adjustment section included in the load controller; FIG. 3B is an example of a block diagram illustrating in more detail the load controller shown in FIG. 3A; FIG. 3B is another example of a block diagram illustrating in more detail the load controller shown in FIG. 3A; FIG. FIG. 5 is a waveform diagram showing an operation example when a load is generated by the electric linear motion actuator.

<<Configuration of Electric Brake Device>>
An electric brake device 1A to which an electric linear motion actuator 1 according to one embodiment of the present invention is applied will be described. 1A includes an electric brake control device 100A as an example of the control device 100, a brake actuator 500A as an example of an actuator 500 using a linear motion mechanism, and a brake instruction means 300A such as a brake pedal as an example of the instruction means 300. A configuration example of an electric brake device 1A is shown. The electric brake device 1A is for a vehicle brake in this embodiment.

<<Configuration of Brake Actuator 500A>>
The brake actuator 500A includes an electric motor 510, a linear motion mechanism 520 that converts the rotary motion of the electric motor 510 into a linear motion (linear motion) of a friction material 560 described later, and a rotation amount (rotation speed) of the rotor of the electric motor 510. Alternatively, an angle sensor 530 that detects and outputs a rotation angle (hereinafter also referred to as a motor angle), a brake rotor 570 that rotates integrally with the wheel and is an object of load, and a load (or linear motion sensor) that is pressed against the brake rotor 570 A friction material 560 that generates a braking force on (the wheels of) the vehicle by applying a load (also referred to as a braking load in this embodiment), a load sensor 540 that detects and outputs the braking load, and the rotation of the electric motor 510 It is composed of a reduction gear 550 that reduces the number and outputs it to the linear motion mechanism 520 and a speed change mechanism 580 . Depending on the performance requirements of the brake, a configuration in which the speed reducer 550 is not provided may be employed.

The electric motor 510 is, for example, a permanent magnet synchronous motor, which is considered suitable for space saving, high efficiency, and high torque. However, not limited to this, for example, a DC motor using brushes, a reluctance motor not using permanent magnets, an induction motor, or the like can also be applied. Further, it may be a radial gap motor having magnetic poles in the radial direction of rotation, or an axial gap motor having magnetic poles in the direction of the rotation axis.

In this embodiment, the linear motion mechanism 520 is a linear motion mechanism incorporating a speed change mechanism 580 whose equivalent lead changes according to the applied linear motion load. In particular, when a planetary roller screw structure as shown in FIG. 2 which will be described later is applied to a planetary roller screw structure in which the equivalent lead changes when a planetary carrier 524 and a plurality of planetary rolling elements 523 are fastened or separated by a reaction force of a direct-acting load, the structure is preferable because it is simple and saves space. Alternatively, a linear motion mechanism can be used in which a planetary reduction gear provided with a speed change mechanism as described above is combined with various mechanisms such as a ball screw or a ball ramp mechanism that can convert rotational motion into linear motion.

In this embodiment, the transmission mechanism 580 includes a spring member 581 (an example of an elastic member) and a stopper 583 shown in FIG. 2 which will be described later. Note that the speed change mechanism 580 is not limited to being built in the linear motion mechanism 520 as in the present embodiment, and may be, for example, inside the speed reducer 550 outside the linear motion mechanism 520 or in the speed reducer 550. It may also be any other mechanism capable of producing a speed change function.

The angle sensor 530 in FIG. 1A is, for example, a resolver, a magnetic encoder, or the like, and the use of these is highly accurate and highly reliable and is considered suitable. However, not limited to these, various sensors such as an optical encoder can also be applied. Alternatively, as another configuration, without using an angle sensor, for example, angle sensorless estimation can be applied in which the motor angle is estimated from the relationship between voltage and current in a control device to be described later.

The load sensor 540 is, for example, a sensor that detects strain, deformation, etc. according to the load applied by the actuator. However, it is not limited to this, and a pressure-sensitive medium such as a piezoelectric element can also be used. Alternatively, a torque sensor that detects the braking torque of the brake rotor, or an acceleration sensor that detects the longitudinal deceleration of the vehicle in the case of an electric vehicle brake device may be used.

In addition, as elements not shown, the brake actuator 500A may be separately provided with a power supply device for supplying power to each part and various sensors such as a thermistor according to requirements. Also, the brake actuator 500A can be used as a parking brake actuator by providing a mechanism, such as a solenoid or a DC motor, that locks a portion to which the power of the actuator such as the linear motion mechanism 520 is transmitted.

<<Configuration of Electric Brake Control Device 100A>>
The electric brake control device 100A includes a brake controller 110A that performs brake control calculation, which is an example of a load controller 110 that performs load control calculation, a motion state estimator 120 that calculates the operating state of the motor, and a load force that estimates the load force. A braking force estimator 130A for estimating the braking force, which is an example of the force estimator 130, a motor controller 140 for controlling the motor current flowing through the electric motor 510 to obtain a predetermined motor output, and a motor for supplying electric power to the motor. It is composed of a driver 150 and a current sensor 160 for detecting the motor current.

The motion state estimator 120 includes at least an angle estimator 121 that estimates the angle of the electric motor rotor (motor angle) and an angular velocity estimator 123 that estimates the angular velocity of the motor angle. Alternatively, the motion state estimator 120 may be provided with a function of estimating a predetermined calculus value such as an electric motor angular acceleration, a function of estimating a disturbance, etc., instead of having these estimating units. Further, the motor angle may be, for example, an electrical angle phase used for current control, or a total rotation angle corrected for overlap and underlap of an angle sensor used for angle control. It has a function to obtain the necessary physical quantity as appropriate. In addition, instead of the electric motor rotor, the motor angle and angular velocity are determined based on, for example, the rotation angle (rotation speed) of a predetermined portion of the speed reducer obtained based on the speed reduction ratio, the equivalent lead of the screw mechanism, and the like. It may be the determined position or velocity. The configuration for estimating the physical quantity may be, for example, a configuration of a state estimation observer or the like, or may be a direct calculation such as back calculation based on differentiation or inertia equations.

For the current sensor 160, for example, a sensor consisting of an amplifier that detects the voltage across the shunt resistor provided in the energization path, or a non-contact sensor that detects the magnetic flux around the energization path, or the like can be used. Alternatively, the current sensor 160 may be configured to detect a terminal voltage or the like of an element constituting a motor driver, for example. Also, the current sensor 160 may be provided between each phase of the electric motor, or one or more may be provided on the low side or high side. Alternatively, feedforward control can be performed by calculating a current value based on motor characteristics such as inductance and resistance without providing a current sensor.

The brake controller 110A sets an operation amount for the brake actuator 500A to desirably follow a predetermined command input (specifically, a brake force command value or a press force command value; load command values in FIGS. 3A and 3B). and convert it into a motor drive signal. It mainly controls the stroke position [or (linear motion) stroke amount (equivalent to the amount of movement of the friction material 560)] of the so-called rod of the component that performs the linear motion of the linear motion mechanism 520, and the friction material 560 and the brake rotor 570 A braking force control unit 113A (an example of the load force control unit 113 for controlling the load force generated by conversion of the linear motion mechanism into linear motion) for controlling the braking force generated by the contact of the linear motion mechanism), and the load condition and a control gain adjustment unit 115 that adjusts the control gain calculated in the braking force control unit 113A in response to .

The braking force control unit 113A (that is, the load force control unit 113) adjusts the motor rotation amount based on, for example, an equivalent lead when using a screw mechanism, a reduction ratio when a reduction gear is provided, or various specifications of the actuator 500. (or motor angle) to determine the motor drive amount of the electric motor 510 so as to control the linear motion stroke amount of the linear motion mechanism 520 . Alternatively, the brake force control section 113A may be provided with a stroke sensor or the like (not shown) separately, and may have a function of feedback-controlling the sensor signal to follow a predetermined target value. In addition, the braking force control section 113A can also have a function of setting a stroke amount such that a predetermined gap can exist between the friction material 560 and the brake rotor 570 so that the contact between the friction material 560 and the brake rotor 570 is minimized when the brake is released. . The stroke amount that can be the predetermined gap is, for example, a position where the motor is rotated by a predetermined amount from the motor angle at which the estimated braking force estimated by the braking force estimator 130A is a predetermined value, or a position where the estimated braking force is the motor angle. It can be set as a position where the motor is rotated by a predetermined amount after it stops changing with respect to the transition (or after the amount of change becomes smaller than a predetermined value). In addition, the braking force control unit 113A controls, for example, a very slight braking force that can be difficult to detect with a load sensor that detects the braking force or the above-described torque sensor. You may make it function so that it may become the stroke state which becomes.

Specifically, in this embodiment, the braking force control unit 113A has a function of determining the motor driving amount so that the braking force when the friction material 560 and the brake rotor 570 are brought into contact with each other is controlled to follow a predetermined target value. have In this embodiment, the pressing force between the friction material 560 and the brake rotor 570 is detected by the load sensor 540, and the braking force (estimated braking force) estimated by the braking force estimator 130A, which will be described later, is calculated from the output of the load sensor 540. Although an example functioning based on the above-described brake rotor is shown, the brake force control can also be performed using a torque sensor or the like for detecting the braking torque of the brake rotor.

The control gain adjustment unit 115 uses the motor rotation amount determined from the motor angle of the electric motor 510 and the brake load, which is an example of the actuator load, for the control gain to be applied when the brake force control unit 113A calculates the operation amount. Then, in this embodiment, it has a function of adjusting the control gain in consideration of the non-linear characteristics caused by the speed change mechanism 580 present in the direct acting mechanism. This nonlinear characteristic is described below.

(1) In the linear motion mechanism 520 of the present embodiment, when the planetary carrier 524 and the rotating shaft 521 in FIG. and the rotating shaft 521 separate from each other and the planetary rolling element 523 rotates (referred to as a separated rotation state), the equivalent lead becomes relatively small due to the planetary deceleration effect. That is, when the state changes between the integral rotation state and the separated rotation state, the stiffness, which is the correlation between the motor rotation amount and the brake load, becomes a discontinuous stiffness corresponding to at least the presence or absence of the planetary deceleration effect. . In other words, the change gradient of one of the motor rotation amount and the brake load with respect to the other becomes a rigidity that changes discontinuously by at least the deceleration ratio due to the planetary deceleration effect.

(2) For example, when an elastic member (in this embodiment, a spring member) 581 that deforms due to the reaction force of the linear motion load is used as a means for fastening or separating the planetary carrier 524 and the planetary rolling element 523, the spring member The closer the amount of deformation of 581 is to zero, the better the performance is. Therefore, while the spring member 581 is deformed, the rigidity of the spring member becomes discontinuous, especially when the deformation of the spring member 581 reaches the limit and the deformation becomes impossible.

In addition, in this embodiment, for example, a function of providing a predetermined clearance between the friction material 560 and the brake rotor 570 when the braking force is set to zero may be provided. Further, in the braking force control unit 113A, an arithmetic expression for deriving the motor angle and angular velocity based on the feedback deviation of the braking force is used as the motor driving amount for following and controlling the braking force to a desired target value. A minor control loop may be provided separately for feedback of

The motor controller 140 has a function of controlling the motor current in accordance with a predetermined motor drive signal output from the braking force controller 110A (load controller 110). The motor controller 140 stores the optimum current conditions in a LUT (Look Up Table) in advance in order to obtain a predetermined torque at a predetermined motor angular velocity, and calculates the target current from the current motor angular velocity. A function of determining a value and controlling to achieve the current value is considered to be suitable because high-precision control can be performed at a low cost. However, the present invention is not limited to this, and it is also possible to obtain a drive condition in real time by calculating a relational expression between current, voltage, etc. for deriving the output of the electric motor 510 .

The motor driver 150 is composed of a bridge circuit using switching elements such as FETs (Field Effect Transistors), and determines the voltage applied to the motor based on a predetermined duty ratio (the ratio of the high time and low time of the voltage applied to the motor). A configuration that performs PWM (Pulse Width Modulation) control is considered to be suitable because of its low cost and high performance. Alternatively, the motor driver 150 may be provided with a transformer circuit or the like and configured to perform PAM (Pulse Amplitude Modulation) control.

The braking force estimator 130A, which is an example of the load force estimator 130, has a function of estimating the braking force generated by the contact between the brake rotor 570 and the friction material 560. Specifically, braking force estimator 130A receives an input from load sensor 540 and outputs an estimated braking force.

The brake instruction means 300A can use various operation means that can be operated by the operator, such as a volume, joystick, switch, etc., instead of the brake pedal.

The vehicle motion control device 700 includes an automatic brake function unit (not shown) that prevents the vehicle from colliding or reduces the impact of the collision, and at least brakes to prevent the vehicle from spinning or the like when the vehicle is skidding. Equipped with a side-slip prevention function unit, an anti-skid control unit to prevent vehicle behavior from becoming unstable due to locking of the wheels by the brakes, etc. output. The vehicle motion control device 700 is an integrated control device that integrates information from on-vehicle sensors (not shown) such as a gravity sensor, objective sensor, GPS (Global Positioning System), etc., and performs calculations necessary for the various functions described above. There may be. The brake operation amounts determined by the vehicle motion control device 700 are also transmitted to the electric brake control device 100A as the target braking force or part of the target braking force.

<<Others>>
A power supply device may be provided as a non-illustrated element, and the power supply device may be, for example, a low-voltage battery or a step-down converter for stepping down a high-voltage battery in an electric brake system for automobiles. Alternatively, a high-capacity capacitor or the like can be used, or these can be used in parallel for redundancy. In addition, it is preferable that the power output is directly supplied to the motor driver and the solenoid driver, and that a small step-down converter is applied in the electric brake control device 100A to the various computing units and functional units to step down the voltage, or , various calculators and functional units may be directly supplied with power output, and either or both of the motor driver and the solenoid may be supplied with power via a boost converter.

In addition, the above various arithmetic units and functional units are preferably configured with electronic components such as processors such as microcomputers that operate programs, FPGA (Field Programmable Gate Array), ASIC (Application Specific Integrated Circuit), etc., because they are inexpensive and have high performance. it is conceivable that. The functional blocks shown in the figure are provided for the convenience of description only, and do not limit the specification of the hardware or software configuration, the division of functions, etc., and the functions of each block can be integrated or divided as necessary. You may Further, the specific configuration of software and hardware can be arbitrarily configured as long as the functions shown in this embodiment are not hindered. Elements not shown may be added as long as they do not interfere with the functions of the present embodiment. For example, it is preferable to add a safety mechanism in case various functions or sensors fail based on system requirements.

The electric brake device 1A can also be applied as a brake device for stopping an energy storage device such as a lifting device, a power generator, or a flywheel, in addition to a vehicle brake device.

An electric press device 1B to which an electric linear motion actuator 1 according to another embodiment of the present invention is applied will be described. FIG. 1B shows an electric press apparatus comprising an electric press control device 100B as an example of the control device 100, a press actuator 500B as an example of an actuator 500 using a linear motion mechanism, and a press device controller 300B as an example of an instruction means 300. 1B shows a configuration example. The electric press apparatus 1B differs from the electric brake apparatus 1A of the previous embodiment in that the object to which the load is applied is the press object 590 of the press actuator 500B instead of the brake rotor 570 of the brake actuator 500A. be. In the electric press device 1B, those having the same reference numerals as those of the electric brake device 1A basically have the same functions, so their functions can be presumed and will not be described below.

The press controller 110B of the electric press control device 100B is an example of the load controller 110 that performs load control calculations, and performs press control calculations and the like. The press load estimator 130B is an example of the load force estimator 130 that estimates the load force, and estimates the press force (or press load) from the drive mechanism 520 to the press object 590. FIG.

The press load controller 113B (an example of the load controller 113) of the press controller 110B is an example of the load force controller 113 for controlling the load force generated by converting the linear motion of the linear motion mechanism into linear motion. The press load control section 113B has a function of determining a motor drive amount so that the press force from the drive mechanism 520 to the object to be pressed 590 is controlled to follow a predetermined target value. In the press load control section 113B of the present embodiment, the press force is detected by the load sensor 540, and functions based on the press force (estimated press force) estimated by the press load estimator 130B from the output of the load sensor 540. Give an example.

<<Structural Example of Linear Motion Mechanism 520>>
FIG. 2(a) shows a schematic diagram of a linear motion mechanism 520 having a speed change mechanism 580 in an unloaded (unloaded) state. A planetary carrier 524 supporting a plurality of planetary rolling elements 523 is pressed against a stopper 583 by a spring member 581, which is an elastic member. By integrally rotating with the shaft 521 (integrally rotating state), the operation is the same as that of a general sliding screw.

FIG. 2(b) shows a schematic diagram of the linear motion mechanism 520 having the speed change mechanism 580 when a linear motion load of a predetermined value or more is applied. The spring member 581 is compressed by Δ due to reaction force transmitted from the outer ring 525 against the force applied by converting the rotational force of the rotary input shaft 521 into a linear load via the planetary rolling element 523 . As a result, the pressing of the planetary carrier 524 against the stopper 583 is released, the integration of the planetary carrier 524 and the rotation input shaft 521 is released, the planetary rolling element 523 rotates (separate rotation state), and the rotation is input. A planetary deceleration effect occurs in which a difference in rotational speed occurs between the shaft 521 and the planetary carrier 524, thereby reducing the equivalent lead compared to the case of FIG. 2(a).

<<Configuration example of load controller 110>>
FIG. 3A shows a configuration example of the load controller 110 including the brake controller 110A of FIG. 1A and the press controller 110B of FIG. 1B. The load target value (command input) and the estimated load in the figure are the braking force command value and the estimated braking force, respectively, when the brake controller 110A is configured, and the press force command when the press controller 110B is configured. value and estimated press force.

The load control unit 113 derives a motor drive amount for causing the estimated load value of the actual machine to follow the load target value. For example, it is possible to calculate the deviation between the load target value and the load estimated value, and obtain the manipulated variable that makes the deviation zero or within an allowable error range.

The control gain adjustment unit 115 has a function of acquiring a load target value, deriving a control gain setting value according to the load target value, and updating the control gain of the load control unit 113 to the control gain setting value. This control gain set value is a value that changes discontinuously corresponding to discontinuous nonlinear stiffness (for example, due to the transmission mechanism shown in FIG. 2).

In the load control unit 113, for example, PID compensation (or PID control [Proportional Integral Differential Control]) is performed on the deviation between the estimated value of the load and the target value of the load. In this case, the control gain adjustment unit 115 may have a function of adjusting one constant gain related to all gains of P control [Proportional Control], I control [Integral Control], and D control [Differential Control]. , P-control, I-control, and D-control gains may be individually adjusted. Alternatively, for example, when a state feedback controller having a predetermined feedback loop eigenvalue is applied in the load control section 113, the control gain adjustment section 115 may have a function of adjusting at least the time constant of the eigenvalue. These adjusted values can be derived by a predetermined calculation formula, but the specification is to store predetermined design values according to the load in advance in a LUT (Look Up Table), etc., and refer to the LUT, etc. Then, the amount of calculation can be reduced, which is preferable.

Also, in this embodiment, the motor drive amount indicates a motor torque command value, which is considered preferable because the controller can be designed based on a simple equation of motion. However, the present invention is not limited to this, and may be configured to derive, for example, a motor current command value or a voltage to be directly applied to the motor.

FIG. 3B shows an example of a configuration in which the control gain adjustment unit 115 in FIG. 3A refers to the estimated load instead of the load target value as an input to determine the control gain. Since it is the same as FIG. 3A except for this difference, detailed description is omitted. For calculation of the control gain setting value, for example, the configuration of FIG. 3A and the configuration of FIG. 3B can be used together to use an intermediate value such as a weighted average value of the load target value and the estimated load.

<<Control Gain Adjustment Unit 115>>
4A to 4E show the nonlinear stiffness (pressure increase characteristic, pressure decrease characteristic) when the linear motion mechanism 520 having the transmission mechanism 580 of FIG. 2 is applied, and the control gain adjustment section 115 of FIGS. (actuator load vs. motor rotation amount and control gain characteristic diagram). In the upper diagram of each figure, the solid line indicates the pressure increase characteristic during pressure increase, and the dashed line indicates the pressure reduction characteristic during pressure reduction.

The lower diagrams of FIGS. 4A to 4E show control gains with respect to actuator loads (or linear motion loads). If the change gradient of the motor rotation amount with respect to the actuator load (referred to as the motor rotation amount change gradient) or vice versa, the discontinuity point is defined as the point where the change gradient of the actuator load with respect to the motor rotation amount changes discontinuously. In the embodiment, there are two points of discontinuity in rigidity in each of the pressure-increasing characteristics and the pressure-decreasing characteristics in the figure. The second point is a discontinuous point due to deformation such as the deformation limit of the spring member (elastic member) of the transmission mechanism. Here, the term discontinuity means that even if microscopically it shows continuity that gradually changes, macroscopically looking at the full scale, if the above-mentioned change gradient changes extremely sharply, it means that the above-mentioned Included in discontinuity. Conversely, discontinuities between samples due to discretization in discretized information, such as LUTs, shall not be included in the aforementioned discontinuities.

Here, for example, when adopting a structure in which the amount of deformation of the spring member is extremely close to zero, or a spring member that does not reach the deformation limit even when the linear motion mechanism 520 applies the maximum load, the above-mentioned There may be control gains in which there is no second discontinuity.

In general, the nonlinear stiffness of the linear motion mechanism during pressure increase and decompression has nonlinearity that does not match during pressure increase and decompression due to factors such as friction at the contact part of the member where deformation occurs. (Hysteresis characteristics described above), the tendency of mismatching differs depending on the linear motion mechanism employed. In addition, the nonlinearity may change due to aging or wear, and the nonlinearity may also change depending on the operation history such as how much load is generated. That is, at least in the area (intermediate area) where the characteristics of the pressure increase side and the pressure decrease side are different in the control gain with respect to the actuator load shown in the figure, it is difficult to clearly grasp in advance what kind of rigidity is exhibited.

Regarding FIG. 4A, when the pressure is increased, when the actuator load is low, the equivalent lead is changed at the first predetermined actuator load F1a from the unitary rotation state to the separated rotation state. A discontinuity occurs where the motor rotation amount change gradient with respect to the actuator load increases. Compared to the pressure increase characteristic, the equivalent lead is large and the motor rotation amount change gradient is relatively small at F1a. At the time of decompression, when the actuator load F2a is larger than F1a, the shift occurs again from the separated rotation state to the integral rotation state, so the first point of discontinuity when viewed from the side where the actuator load is low occurs. It shows the characteristics of

At this time, the control gain in the control gain adjustment unit 115 transitions from a low state to a high state at the first discontinuous point when viewed from the low load side, and in the section from F1a to F2a is a state in which the control gain is low, and the discontinuity point of F2a on the pressure reduction side is adopted as the discontinuity point. According to this, although the equivalent lead is large, the motor is driven by a large force on the assumption that the equivalent lead is small. The discontinuity point of the control gain may be a discontinuity point at a load that is sufficiently closer to F2a than F1a. A slightly larger load may be set.

In this embodiment, high and low control gains mean that the absolute values of coefficients to be actually multiplied are large and small. It also includes the meaning of being large (=slow).

Also, when the actuator load is increased and viewed from the lower actuator load side, at the second actuator load F3a, the spring member (elastic member) 581 of the transmission mechanism 580 reaches its deformation limit, and the motor rotation amount change with respect to the actuator load. A discontinuity occurs where the slope decreases. When the pressure is reduced, the predetermined actuator load F4a, which is smaller than F3a, is the second point of discontinuity when viewed from the low actuator load side. At this time, the control gain in the control gain adjustment unit 115 transitions from a high state to a low state at the second discontinuity point when viewed from the low load side, and in the section from F4a to F3a is a state in which the control gain is low, and adopts a characteristic having a discontinuous point of F4a on the pressure reduction side as the discontinuous point. According to this, although the equivalent lead is large, the motor is driven by a large force on the assumption that the equivalent lead is small. The discontinuity point of the control gain may be a discontinuity point at a load that is sufficiently closer to F4a than F3a. A slightly smaller load may be set.

Regarding FIG. 4B, when the pressure is increased, when the actuator load is low, the equivalent lead is changed at the first predetermined actuator load F1b from the integral rotation state to the separated rotation state. A discontinuity occurs where the motor rotation amount change gradient with respect to the actuator load increases. When the pressure is reduced, the actuator load F2b, which is smaller than F1b, changes from the separated rotation state to the integral rotation state and shift occurs again. doing. Compared to the pressure increase characteristic, the motor rotation amount change gradient is larger in the load region smaller than F1b in the pressure decrease characteristic.

At this time, preferably, in the section from F2b to F1b, the control gain is in a low state, and the discontinuity point of F1b on the pressure increasing side is adopted as the discontinuity point. The discontinuity point of the control gain may be a discontinuity point at a load that is sufficiently closer to F1b than F2b, or the discontinuity point is slightly larger than F1b, considering the characteristic variation and aging of each actuator. You can set the load. Note that the control gain in the interval from F4b to F3b, where a discontinuous point occurs due to the deformation of the spring member in each characteristic of increasing/decreasing pressure, can be set in the same manner as in the interval from F4a to F3a in FIG. 4A.

Regarding FIG. 4C, at the second predetermined actuator load F3c when viewed from the low actuator load side during pressure increase, the spring member (elastic member) 581 of the transmission mechanism 580 reaches its deformation limit, and the actuator load A discontinuity occurs where the motor rotation amount change gradient decreases. When the pressure is reduced, the predetermined actuator load F4c larger than F3c is the second point of discontinuity when viewed from the low actuator load side.

At this time, preferably, the control gain in the control gain adjusting section 115 is in a low state in the section from F3c to F4c, and the discontinuity point of F3c on the pressure increasing side is adopted as the discontinuity point. The discontinuity point of the control gain may be a discontinuity point at a load that is sufficiently closer to F3c than F4c. You can set the load. The control gain in the section from F1c to F2c where a discontinuity occurs due to the change in the equivalent lead can be set in the same manner as in the section from F1a to F2a in FIG. 4A.

Regarding FIG. 4D, the control gain can be determined between actuator loads F1d and F2d in the same manner as between F1b and F2b in FIG. 4B, and between actuator loads F3d and F4d in the same manner as F3c to F4c in FIG. 4C. FIG. 4E shows an example of control gain when the electric linear motion actuator 1 having the transmission mechanism 580 is applied to the electric brake device 1A. The pressure increase characteristic, pressure decrease characteristic, and control gain in FIG. 4A are closer to curved lines than straight lines.

In general, an electric brake device has non-linear stiffness due to the non-linear stiffness of friction materials for brakes, etc., but the change is generally continuous. A discontinuous change occurs when applied. Therefore, as a control gain for that, a control gain discontinuity point corresponding to a rigidity discontinuity point by the transmission mechanism 580 can be provided, and a control gain that changes continuously can be used in other areas. The nonlinearity due to pressure increase/decrease is described as showing the same tendency as in FIG. 4A, but if an actuator showing the tendency of FIGS. discontinuity can be set. In addition, although the section excluding the discontinuous point of the control gain shows an example with continuous nonlinearity, the controller may be designed to be robust to some extent and then simplified so that it changes with a constant gradient, or approximately It can also be a constant value.

<<Another example of the control gain adjustment unit 115>>
FIG. 5A shows an example of estimating the nonlinear stiffness and its discontinuity from the motor angle and the estimated load, and adjusting and updating the control gain of the control gain adjuster 115 based on the estimation result. In FIG. 5A, the control gain adjustment unit 115 has a pressure increase control gain 115a that stores a control gain for pressure increase and a pressure decrease control gain 115b that stores a control gain for pressure decrease. Further, it has a control gain switching unit 115c for determining which of the pressure increase control gain 115a and the pressure decrease control gain 115b to refer to.

For example, when it is determined that the motor is rotating toward the pressure increasing side from the transition of the motor angle, the control gain switching unit 115c refers to the control gain of the pressure increasing control gain 115a to determine whether the motor is rotating toward the pressure decreasing side. If it is determined that the control gain is present, the control gain can be switched so as to refer to the control gain of the pressure reduction control gain 115b. Alternatively, the control gain switching unit 115c selects a case where the motor is rotating on the pressure increasing side by a predetermined amount or more, a case when the motor is rotating on the pressure reducing side by a predetermined amount or more, and an intermediate state that does not correspond to any of these. Alternatively, in the intermediate state, reference may be made to a control gain in which the control gains for pressure increase and pressure reduction are combined at a predetermined ratio. Further, instead of the motor angle, it may be determined which of the pressure-increasing control gain 115a and the pressure-decreasing control gain 115b should be referred to as the control gain based on the transition of the estimated load.

Now, in FIG. 5A, in addition to having the control gain adjustment unit 115, a stiffness parameter storage unit 117 and a nonlinear stiffness estimation unit 118 are provided in addition to the configuration of FIG. The stiffness parameter storage unit 117 stores at least the amount of rotation of the electric motor 510 when a change occurs in the load corresponding to the discontinuous point of the control gain stored in advance, and the amount of rotation of the electric motor 510 and the estimated Stores the change history with the applied load. Specifically, the stiffness parameter storage unit 117 includes a pressure increase data storage unit 117a that stores the motor angle and the estimated load during the pressure increase operation, and a pressure decrease data storage unit 117a that stores the motor angle and the estimated load during the pressure decrease operation. and a storage unit 117b.

A nonlinear stiffness estimator 118 estimates a discontinuity in the correlation between the angle of the motor 510 and the load in the control gain from the change history of the angle of the electric motor 510 and the estimated load, and calculates the estimated discontinuity. Update the control gains based on the points. Specifically, the nonlinear stiffness estimator 118 estimates a discontinuity point and applies a predetermined function for deriving the nonlinear stiffness to the motor angle and the estimated load stored in the stiffness parameter storage 117 as follows: It has a convergence calculator 118a that performs parameter fitting to minimize an error, and a control gain calculator 118b that derives the nonlinear stiffness based on the result of the convergence calculator 118a. The parameter fitting in the convergence calculation unit 118a is executed at the stage when the stiffness parameter storage unit 117 has accumulated a sufficient range of data including at least stiffness discontinuities.

In the convergence calculation unit 118a, a function g1(F) indicating the stiffness when the equivalent lead is large, a function g2(F) indicating the stiffness when the equivalent lead is small and the spring member is deformed, and a function g2(F) which indicates the stiffness when the equivalent lead is small and the spring The function g3(F) that indicates the stiffness of the member when no deformation occurs (deformation limit, etc.), the load Fnl1 corresponding to the two points of discontinuity where g1(F) and g2 coincide, and g2(F) Using the load Fnl2 with which g3(F) matches, the nonlinear stiffness is derived for the motor angle θ and the load F as follows.

where any two constant terms of g1(F), g2(F), g3(F) satisfy g1(Fnl1) = g2(Fnl1), g2(Fnl2) = g3(Fnl2) is adjusted, and the constant term Fc of one function out of g1(F), g2(F), g3(F) excluding the above two is used as a parameter fitting variable described later.

The convergence calculation unit 118a performs a convergence calculation such as Newton's method on each data sample θ1 . . . θk and F1 . Using an arithmetic algorithm, variables of two discontinuous points Fnl1, Fnl2, and a constant term Fc that minimize the following error function J in the θ=f(F) formula are calculated.

The control gain calculation unit 118b derives control gains during pressure increase and pressure reduction based on the above calculation results of the convergence calculation unit 118a. After the derivation of the control gain is completed, the control gain of the control gain adjuster 115 is updated. The control gains are obtained by determining the control gains for each function based on the derivation results of the stiffness functions g1, g2, and g3, and connecting them so that they are switched under the load conditions corresponding to the discontinuous points Fnl1 and Fnl2. can be derived as Alternatively, instead of the control gain for each function, the derivation process may be simplified by using a control gain that is combined so as to switch under load conditions corresponding to the discontinuous points Fnl1 and Fnl2. . At this time, the functions g1, g2, and g3 in the convergence calculation section can also be fixed functions, and the calculation process can be further simplified.

After the derivation of the control gain is completed, the discontinuity point of the control gain stored in the control gain adjustment section is updated by the control gain adjustment section 115 based on the derived discontinuity point of the control gain. At this time, the point of discontinuity is determined according to the method described with reference to FIGS. 4A to 4E for each of the control gains during pressure increase and pressure decrease.

The control gains for the pressure increase control gain and the pressure decrease control gain may be updated at the same time, or may be updated individually at arbitrary timings.

In addition to the above-described operations, control device 100 estimates and stores the amount of change in either one of the load and the amount of rotation when a predetermined amount of change in load or the amount of rotation of electric motor 510 occurs. good too. Further, control device 100 compares the stored amount of change with the amount of change newly estimated after the storage. It may be determined that a point of discontinuity between the angle and the load has occurred, and the control gain may be updated based on the determined point of discontinuity.

Note that, as elements not shown, when the control gain is switched by the control gain switching unit 115c of the control gain adjusting unit 115, when the control gains of the control gains 115a and 115b during pressure increase and pressure decrease are updated, etc. It is preferable to provide a function of appropriately resetting internal parameters so that unnecessary motor drive commands are not calculated by the load control unit 113 .

FIG. 5B shows a first control gain 115d adjusted by the control gain adjustment unit 115 to a control gain when the equivalent lead of the linear motion mechanism is large, unlike FIG. A second control gain 115e adjusted to a control gain in a state where the member deforms, and a third control gain 115f adjusted to a control gain in a state where the equivalent lead is small and the spring member reaches the deformation limit. In FIG. 5B, instead of using the control gains shown in FIG. 3A, etc., the first to third control gains are appropriately switched and referred to, so that nonlinear control having two discontinuous points as shown in FIG. 3A, etc. This has the same effect as referring to the gain (which may include the control gain during pressure increase and the control gain during pressure decrease in FIG. 5A). Therefore, the control gain adjustment section 115 of FIG. 5B further includes a control gain switching section that switches to and refers to any one of the first to third control gains. Also, in FIG. 5B, there is a discontinuity point estimation unit 119 . The first to third control gains may each be a constant value as shown in the figure, but they may also vary such that they continuously increase or decrease with respect to the load. There may be.

The discontinuity point estimator 119 includes a gradient change calculator 119a that derives a gradient of change with respect to a change in either one of the motor angle and the estimated load, and an already stored gradient of change and the derivation result of the gradient calculator 119a. and a change gradient comparison unit 119b for newly storing the derivation result of the change gradient calculation unit.

The change gradient calculator 119a may have a function of evaluating the amount of change in either one of the motor angle and the estimated load when the other changes by a predetermined amount. For example, specifically, the function may be such that the change gradient is Fdelta/θdelta for the load change amount Fdelta when the motor angle changes by a predetermined θdelta. Alternatively, (F(t+dt)-F(t))/(θ(t+dt)-θ(t)) may be used as the change gradient for the angle and load change for the predetermined time dt.

The change gradient comparison unit 119b compares the change gradient that has already been stored with the derived change gradient, and can determine that a stiffness discontinuity has occurred if the comparison result shows a change of a predetermined amount or more. . If it is determined to be a discontinuous point, information on the discontinuous point is transmitted to control gain adjustment section 115 .

For example, when it is determined that a point of discontinuity has occurred while referring to the control gain of the first control gain 115d in the pressure increasing direction, the control gain switching unit 115c switches the control gain of the second control gain 115e. may transition to a state that refers to In addition, in the pressure increasing direction, when it is determined that a discontinuity point occurs while the control gain of the second control gain 115e is being referred to, the state is shifted to the state of referring to the control gain of the third control gain 115f. In the pressure reduction direction, when it is determined that a point of discontinuity has occurred while the control gain of the second control gain 115e is being referred to, the control gain of the first control gain 115d is referred to. You can move to In the pressure reduction direction, when it is determined that a point of discontinuity has occurred while the third control gain 115f is being referred to, the second control gain 115e may be referred to.

As a non-illustrated element, when the control gain is switched by the control gain switching unit 115c of the control gain adjusting unit 115, a function to appropriately reset internal parameters so that the load control unit 113 does not calculate an unnecessary motor drive command. is preferably provided.

<<Example of Operation of Electric Brake Device 1A>>
FIG. 6 shows an operation example of generating a predetermined braking force from a no-load state in which a predetermined clearance is provided between the friction material 560 and the brake rotor 570. FIG. FIG. 1(a) shows an example of application of the electric linear motion actuator 1 described in the above embodiment to which the linear motion mechanism 520 having the transmission mechanism 580 illustrated in FIG. 2 is applied. In the same figure (a), the brake force FF can be exerted without overshoot due to deterioration of controllability due to the occurrence of non-linear shift operation. A braking force is generated at a relatively short time TT1 from the state until the braking force is generated. FIG. 1(b) shows an example of operation by a conventional electric linear motion actuator to which a linear motion mechanism without a speed change mechanism is applied. In FIG. 4(b), since the equivalent lead of the linear motion mechanism is constant, it takes a relatively long time from the no-load state to the time TT2 at which the braking force is generated. FIG. 1(c) shows an example in which the linear motion mechanism 520 having the speed change mechanism 580 shown in FIG. In the same figure (c), since the equivalent lead of the linear motion mechanism has been changed, the braking force can be generated in a relatively short time TT1 from the no-load state until the braking force is generated. , the controllability deteriorates, and a relatively large overshoot occurs before the braking force FF is exhibited.

As described above, the preferred embodiment has been described with reference to the drawings, but various additions, changes, and deletions are possible without departing from the scope of the present invention. Accordingly, such are also included within the scope of this invention.

1 electric linear motion actuator 1A electric brake device (electric linear motion actuator)
1B electric press device (electric linear actuator)
100 control device 100A electric brake control device (control device)
100B electric press control device (control device)
113 load controller 113A braking force controller (load controller)
113B Press load control unit (load controller)
115 control gain adjustment unit 115a pressure increase control gain 115b pressure decrease control gain 115c control gain switching unit 115d first control gain 115e second control gain 115f third control gain 117 stiffness parameter storage unit 118 nonlinear stiffness estimation unit 119a Gradient change calculation unit 119b Gradient change comparison unit 510 Electric motor 520 Linear motion mechanism 523 Planetary rolling element 524 Planetary carrier 530 Angle sensor (estimator for estimating the amount of rotation of the electric motor)
540 load sensor (estimator for estimating the load applied by the linear motion mechanism)
570 brake rotor (object)
580 transmission mechanism 581 spring member (elastic member) (transmission mechanism)
583 stopper (transmission mechanism)

Claims (7)

1. an electric motor, a linear motion mechanism that converts rotary motion of the electric motor into linear motion, a control device that drives the electric motor and controls the load that the linear motion mechanism applies to an object due to the linear motion; a speed change mechanism having a speed change function in which the correspondence relationship between the amount of linear motion of the linear motion and the amount of rotation of the electric motor changes with respect to a predetermined load;
   The control device is
   an estimator for estimating the load applied by the linear motion mechanism;
   In the process of deriving the drive amount of the electric motor, at least one or more of a deviation between the estimated value of the load and the target value of the load, an integral value of the deviation, and a differential value of the deviation The control gain to be multiplied is used for control calculation, and in a state in which at least one of the estimated value of the load and the target value is not zero, the estimated value of the load and the target value at least at one or more locations. a load controller that calculates a motor drive amount using a control gain that changes discontinuously with respect to the transition of at least one of
   a control gain adjustment unit that adjusts the control gain used in the load controller according to the load condition;
   having
   Electric linear actuator.
2. The electric linear motion actuator according to claim 1,
   The transmission mechanism includes a first equivalent lead state in which the amount of linear motion has a predetermined correlation with respect to the amount of rotation of the electric motor, and the first equivalent lead state with respect to the amount of rotation of the electric motor compared with the first equivalent lead state. and a second equivalent lead state in which the amount of linear motion is correlated with a small amount, and
   In the process of increasing the load applied by the linear motion mechanism, the shift function switches from the first equivalent lead state to the second equivalent lead state when the first shift load, which is the predetermined load, is exceeded. , in the process of reducing the load applied by the linear motion mechanism, when the load falls below the second shift load, which is the predetermined load different from the first shift load, the second equivalent lead state changes to the first shift load. has a non-linearity that switches to the equivalent lead state,
   Regarding the control gain, the control gain on the side of the load smaller than the first discontinuity point where the transition of the control gain with respect to the load transition is discontinuous is greater than the control gain on the side of the load larger than the first discontinuity point. including the first point of discontinuity that becomes smaller;
   The transmission function having non-linearity and the control gain of the transmission mechanism meet any of the following conditions i) and ii):
   Electric linear actuator.
   i) the first shift load of the shift function is greater than the second shift load, and the first discontinuity point of the control gain is greater than the second shift load to the first shift load; close.
   ii) the second shift load of the shift function is greater than the first shift load, and the first discontinuity point of the control gain is greater than the first shift load to the second shift load; close.
3. The electric linear motion actuator according to claim 1 or 2,
   The linear motion mechanism is
   a rotation input member, a planetary carrier rotatably supported concentrically with the rotation input member, a planetary rolling element rotatably supported by the planetary carrier;
   The planetary rolling element does not rotate due to the elastic force, and the rotation input member and the planetary carrier are synchronously rotated. and an elastic member that rotates the planetary rolling element and causes a difference in the amount of rotation between the rotation input member and the planetary carrier,
   In the process in which the load applied by the linear motion mechanism increases, the elastic member completes deformation when a predetermined first deformation load is exceeded, and in the process in which the load applied by the linear motion mechanism decreases. has a non-linear deformation characteristic in which the elastic member begins to deform when falling below a second deformation load different from the first deformation load,
   With respect to the control gain, the control gain on the side of the smaller load from the second discontinuity point where the transition of the control gain with respect to the transition of the load is discontinuous is greater than the control gain on the side of the larger load than the second discontinuity point. including the growing second point of discontinuity;
   The deformation characteristics and the control gain of the elastic member of the linear motion mechanism meet any of the following conditions i) and ii):
   Electric linear actuator.
   i) the first deformation load of the elastic member is greater than the second deformation load, and the second discontinuity of the control gain is greater than the first deformation load to the second deformation load; close.
   ii) the second deformation load of the elastic member is greater than the first deformation load, and the second discontinuity point of the control gain is closer to the first deformation load than the second deformation load; close.
4. In the electric linear motion actuator according to any one of claims 1 to 3,
   The control gain adjustment unit includes a control gain for increasing pressure, which is the control gain for increasing pressure when the load increases, a control gain for decreasing pressure, which is the control gain for decreasing pressure when the load decreases, and the control for increasing pressure. a control gain switching unit that determines which of the gain and the control gain of the pressure reduction control gain is to be referred to,
   The control gain switching unit refers at least to the control gain of the pressure increasing control gain when the motor is rotating on the pressure increasing side based on transition of the motor angle, and when the motor is rotating on the pressure decreasing side, the pressure reducing control gain. switching the control gain to refer to the control gain of the time control gain;
   Electric linear actuator.
5. In the electric linear motion actuator according to claim 3,
   The control gain adjustment unit adjusts a first control gain, which is a control gain of the electric motor when an equivalent lead corresponding to the amount of linear motion of the linear motion with respect to the amount of rotation of the electric motor is large, and a second control gain that is the control gain when the elastic member deforms; a third control gain that is the control gain when the equivalent lead is small and the elastic member reaches a deformation limit; Having a control gain switching unit that switches to any one of the first to third control gains and uses it as a reference,
   The electric linear motion actuator further comprises:
   a change gradient calculation unit that derives a gradient of change of one of the motor angle and the estimated load with respect to the change of the other;
   storing the gradient of change derived by the gradient-of-change computing unit; comparing the stored gradient of change with the gradient of change newly derived by the gradient-of-change computing unit after storing; a change gradient comparison unit that determines that a control gain discontinuity exists when the gradient changes,
   The control gain switching unit uses the first to third control gains, and if there are a plurality of discontinuous points, at least one of the plurality of discontinuous points determined by the change gradient comparing unit according to
   When it is determined that the point of discontinuity has occurred when the load changes in the direction of increasing pressure while referring to the first control gain, referring to the second control gain,
   In the state of referring to the second control gain, when the pressure is changed in the direction of pressure increase, when it is determined that the discontinuity has occurred, the third control gain is referred to, and when the pressure changes in the direction of pressure reduction, referring to the first control gain when it is determined that the discontinuity point has occurred;
   In a state in which the third control gain is referred to, the second control gain is referred to when it is determined that the discontinuity has occurred when the pressure changes in the direction of pressure reduction.
   Electric linear actuator.
6. In the electric linear motion actuator according to any one of claims 1 to 5,
   The control device is
   an estimator for estimating the rotation angle of the electric motor;
   A rotation amount of the electric motor and the estimated load when a change in the load of a predetermined amount occurs in a range including at least the load corresponding to the discontinuity point of the control gain stored in advance. Having a stiffness parameter storage unit that stores a change history,
   Further, the control device
   a nonlinear stiffness estimating unit that estimates a point of discontinuity in the control gain from the angle of the electric motor and the change history of the estimated load, and updates the control gain based on the estimated point of discontinuity; ,
   Electric linear actuator.
7. In the electric linear motion actuator according to any one of claims 1 to 5,
   The control device is
   an estimator for estimating the rotation angle of the electric motor;
   estimating and storing an amount of change in either one of the load and the amount of rotation when a predetermined amount of change in the load or the amount of rotation of the electric motor occurs, and
   Further, the control device
   The stored amount of change is compared with the amount of change newly estimated after the storage, and if the amount of change changes more than a predetermined amount, the angle and load of the electric motor at the control gain are determined. determining that a discontinuity point has occurred, and updating the control gain based on the determined discontinuity point;
   Electric linear actuator.

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