JP2022130074A - Electrically-driven direct-acting actuator - Google Patents

Abstract

To provide an electrically-driven direct-acting actuator that can perform high-accuracy load control, by taking into consideration discontinuous stiffness including a discontinuous correlation between a motor rotation speed and a load, which is caused based on a change gear ratio in a speed change mechanism.SOLUTION: The electrically-driven direct-acting actuator comprises: an electric motor; a direct-acting mechanism; a control device that drives the electric motor and controls a load that is applied by the direct-acting mechanism to an object by linear motion; and a speed change mechanism having a speed change function of changing a correspondence relation between amounts of direct action of the linear motion and rotation speeds of the electric motor after the load reaches a predetermined load. The control device has: estimators that estimate the rotation speeds of the electric motor and loads that are applied by the direct-acting mechanism; a memorizing part that memorizes a correlation in stiffness between the rotation speeds of the electric motor in a state where the loads are not zero and the loads that a transition of gradients of change of either of the rotation speeds of the electric motor and the loads with respect to the other is discontinuous; and a load controller that drives the electric motor so that at least the loads estimated based on the correlation of stiffness follow a target value.SELECTED DRAWING: Figure 1A

Description

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.

2. Description of the Related Art Conventionally, 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

Generally, in applications such as an electric brake using an electric linear motion actuator, 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 account discontinuous stiffness, such as discontinuous correlation between motor rotation amount and load, which occurs based on the gear ratio in a transmission mechanism. Another object of the present invention is to provide an electric linear motion actuator capable of highly accurate load control.

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
each estimator for estimating the amount of rotation of the electric motor and the load applied by the linear motion mechanism;
Stores a stiffness correlation between the amount of rotation of the electric motor and the load at which the transition of the change gradient of one of the amount of rotation of the electric motor and the load that is not zero becomes discontinuous with respect to the change of the other. a storage unit;
a load controller that drives the electric motor so that the load estimated based on at least the stiffness correlation follows a target value;
have

According to the above configuration, the electric linear motion actuator according to the present invention applies a discontinuous correlation between the motor rotation amount and the load based on the gear ratio under load conditions under which gear shifting occurs. Considering the discontinuous stiffness such as the discontinuous correlation between the motor rotation amount and the load generated based on the gear ratio in the mechanism enables highly accurate load control.

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,
In the stiffness correlation stored in the storage unit, the change gradient of the electric motor angle with respect to the load change on the side where the load is small from the first discontinuity point where the transition of the change gradient is discontinuous is the first discontinuity. including the first discontinuous point that is smaller than the change gradient of the electric motor angle on the side where the load is larger than the continuum point;
The transmission function having non-linearity of the transmission mechanism and the stiffness correlation 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 stiffness correlation is greater than the second shift load to the first shift load; near.
ii) said second shift load of said shift function is greater than said first shift load, and said first discontinuity point of said stiffness correlation is greater than said first shift load to said second shift load; near.
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,
According to the stiffness correlation stored in the storage unit, the change gradient of the electric motor angle with respect to the load change on the side where the load is small from the second discontinuity point where the transition of the change gradient is discontinuous is the second discontinuity. including the second point of discontinuity that is greater than the gradient of change in the angle of the electric motor on the side where the load is greater than the point of continuation;
The deformation characteristic and the stiffness correlation 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 stiffness correlation is greater than the first deformation load to the second deformation load; near.
ii) the second deformation load of the elastic member is greater than the first deformation load, and the second discontinuity of the stiffness correlation is greater than the first deformation load than the second deformation load; near.
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 above-described unstable actuator operation can be suppressed by operating at least the region where the deformation of the spring is unstable, assuming that the spring does not deform.

In the above configuration, the non-linear stiffness storage unit includes a pressure-increase stiffness storage unit that stores the stiffness correlation during pressure increase when the load increases, and a pressure-increase stiffness storage unit that stores the stiffness correlation during pressure reduction when the load decreases. a stiffness storage unit; and a reference stiffness switching unit that determines which one of the stiffness phases of the pressure increase stiffness storage unit and the pressure reduction stiffness storage unit is to be referred to,
The reference stiffness switching unit refers to the stiffness phase in the pressure increasing stiffness storage unit when the motor is rotating on the pressure increasing side based on at least the transition of the motor angle or the estimated load transition, is rotating, the stiffness correlation may be switched so as to refer to the stiffness correlation in the rigidity storage unit during reduced pressure. 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 increased stably, the characteristics are at the time of pressure increase, and when the pressure is decreased, the characteristics are at the time of pressure reduction. When employing a linear motion mechanism, the actuator can be operated with higher accuracy.

In the above configuration, the nonlinear stiffness storage unit stores a stiffness relationship between the amount of rotation of the electric motor and the load 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. a first rigidity storage unit, a second rigidity storage unit that stores a rigidity relationship between the amount of rotation of the electric motor and the load when the equivalent lead is small and the elastic member is deformed, and the equivalent lead is small. a third rigidity storage unit for storing a rigidity relationship between the amount of rotation of the electric motor and the load when the elastic member reaches a deformation limit; and any one of the first to third rigidity storage units. has a reference stiffness switching part that switches to and is used 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 rigid discontinuity exists when the gradient has changed,
The reference stiffness switching unit uses the stiffness relationships of the first to third stiffness storage units instead of using the stiffness correlation, and the change gradient comparison unit determines when a plurality of the discontinuous points exist. according to at least one of the plurality of points of discontinuity,
When it is determined that the discontinuity point occurs when the load changes in the pressure increasing direction in which the load is increased while referring to the stiffness relationship in the first stiffness storage unit, the stiffness relationship in the second stiffness storage unit is changed. See
When it is determined that the point of discontinuity has occurred when the pressure is changed in the direction of increasing pressure while referring to the stiffness relationship in the second stiffness storage unit, referring to the stiffness relationship in the third stiffness storage unit, When it is determined that the discontinuity has occurred when the pressure is changed in the direction of pressure reduction, the stiffness relationship in the first stiffness storage unit is referred to,
When it is determined that the discontinuous point occurs when the pressure changes in the direction of pressure reduction while referring to the stiffness relationship in the third stiffness storage unit, the stiffness relationship in the second stiffness storage unit may be referred to. good. 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 stiffness relationship 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 higher precision.

In the above configuration, the control device controls the rotation of the electric motor when a change occurs in the load of a predetermined amount within a range including at least the load corresponding to the discontinuous point of the stiffness correlation stored in advance. a stiffness parameter storage unit that stores a change history of the amount and the estimated load;
Further, the control device estimates a point of discontinuity in the correlation between the angle of the motor and the load in the stiffness correlation from the change history of the angle of the electric motor and the estimated load, and calculates the estimated discontinuity. There may be a non-linear stiffness estimator for updating said stiffness correlation based on points. As a result, regarding characteristic fluctuations in the stiffness correlation that may 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 insignificant from the correlation between the motor rotation amount and the load of the actual electric linear motion actuator. By reflecting the result of estimating a change in continuous points in the estimated stiffness, it is possible to control the electric linear motion actuator with higher accuracy at least from the next operation onwards (updating and estimating from log information).

In the above configuration, when a predetermined amount of change in the load or the amount of rotation of the electric motor occurs, the control device estimates and stores the amount of change with respect to one of the load and the amount of rotation of the other. ,
Further, the control device compares the stored amount of change with the amount of change newly estimated after the storage, and if the amount of change changes more than a predetermined amount, the electric motor in the stiffness correlation. It may be determined that a point of discontinuity between the angle of the motor and the load has occurred, and the stiffness correlation may be updated based on the determined point of discontinuity. As a result, regarding characteristic fluctuations in the stiffness correlation that may 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 insignificant from the correlation between the motor rotation amount and the load of the actual electric linear motion actuator. By reflecting the result of estimating the change in continuous points in the estimated stiffness, it is possible to control the electric linear motion actuator with higher accuracy at least from the next operation onward (real-time estimation).

The electric linear motion actuator according to the present invention provides highly accurate load control by considering discontinuous stiffness such as discontinuous correlation between motor rotation amount and load generated based on the gear ratio in the transmission mechanism. becomes possible.

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. 3 is a block diagram of a load controller included in the control device in each of the electric linear motion actuators; FIG. 10 is an example of a characteristic diagram illustrating stiffness correlation of a nonlinear stiffness storage unit included in the load controller; FIG. 11 is another example of a characteristic diagram for explaining stiffness correlation of the nonlinear stiffness storage unit included in the load controller; FIG. FIG. 11 is still another example of a characteristic diagram for explaining stiffness correlation of the nonlinear stiffness storage unit included in the load controller; FIG. FIG. 11 is still another example of a characteristic diagram for explaining stiffness correlation of the nonlinear stiffness storage unit included in the load controller; FIG. FIG. 11 is still another example of a characteristic diagram for explaining stiffness correlation of the nonlinear stiffness storage unit included in the load controller; FIG. FIG. 4 is an example of a block diagram illustrating in more detail the load controller shown in FIG. 3; FIG. FIG. 4 is another example of a block diagram illustrating in more detail the load controller shown in FIG. 3; 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 to be 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 employs a linear motion mechanism incorporating a speed change mechanism 580 in which the equivalent lead changes depending on 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 speed reducer as described above provided with a speed change mechanism is combined with various mechanisms capable of converting rotary motion into linear motion, such as a ball screw or a ball ramp mechanism.

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 it is considered preferable to use them because of their high accuracy and high reliability. 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 or deformation 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 a shunt resistor provided in the current path, or a non-contact sensor that detects the magnetic flux around the current 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 the electric motor phases, 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 obtains 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 value in FIG. 3), It has the function of converting to a motor drive signal. A position control unit 111 that mainly controls the stroke position [or (linear motion) stroke amount (corresponding to the movement amount 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 (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). ) and a nonlinear stiffness storage unit 115 in which the nonlinear stiffness of the brake actuator is stored.

The position control unit 111 is for example an equivalent lead when using a screw mechanism, a speed reduction ratio when a speed reducer is provided, or a direct value converted from a motor rotation amount (or motor angle) based on various specifications of the actuator 500 . It has a function of determining the motor driving amount of the electric motor 510 so as to control the linear motion stroke amount of the driving mechanism 520 . Alternatively, the position control unit 111 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. The position control unit 111 also has a function of setting the stroke amount such that a predetermined gap exists between the friction material 560 and the brake rotor 570 so as to prevent contact between them as much as possible 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 position control unit 111 controls, for example, a very slight braking force that may be difficult to detect by a load sensor that detects the braking force or the above-described torque sensor. It may be made to function so as to make the stroke state to be different.

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. 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 non-linear stiffness storage unit 115 stores the stiffness that is the correlation between 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. It has the function of storing stiffness information (including stiffness correlation and stiffness relationship described below) that takes into account the non-linear characteristics produced by the mechanism 580 . 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, is at least the discontinuous stiffness corresponding to the presence or absence of the planetary deceleration effect. Become. 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.

The stiffness correlation is stiffness information including both of these discontinuous characteristics (1) and (2). The above-mentioned rigidity relationship includes at least the above-mentioned rigidity in the integral rotation state, the above-mentioned rigidity while the spring member 581 is deformed in the separating and rotating state, and the case where the spring member 581 is non-deformable including the deformation limit in the separating and rotating state. is stiffness information including any of the above stiffnesses of

The motor controller 140 has a function of controlling motor current so as to comply with a predetermined motor drive signal output from the braking force controller 110A (load controller 110). The motor controller 140 stores the optimum current condition in advance in a LUT (Look Up Table) 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 the 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 to perform PAM (Pulse Amplitude Modulation) control.

A 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. FIG. 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 volume control, 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, object 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 parts such as processors such as microcomputers that operate programs, FPGAs (Field Programmable Gate Arrays), ASICs (Application Specific Integrated Circuits), etc., because they are inexpensive and have high performance. it is conceivable that. The functional blocks shown in this figure are provided for the convenience of description only, and do not limit the specification of the hardware or software configuration or the division of functions. May be split. 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 be applied not only as a vehicle brake device but also as a brake device for stopping an energy storage device such as a lifting device, a power generator, or a flywheel.

An electric press machine 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. A configuration example of 1B is shown. 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.

A 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 conversion 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 slide 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 greater than or equal to a predetermined value is applied. The spring member 581 is compressed by Δ due to the reaction force transmitted from the outer ring 525 which converts the rotational force of the rotary input shaft 521 into a linear load and applies it 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. 3 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. When the brake controller 110A is configured, the load command value (command input) and the estimated load in the figure are respectively the braking force command value and the estimated braking force, and when configuring the press controller 110B, the press force command value and Estimated press force.

The load command value is converted into an angle command value by the nonlinear stiffness storage unit 115 based on the correlation between the load and the motor rotation amount stored in the same storage unit, that is, the stiffness, and output. At this time, the stiffness stored in the non-linear stiffness storage section is the stiffness including the non-linearity caused by the speed change mechanism of the linear motion mechanism, as described above.

The estimated load is also converted into a motor angle based on the stiffness in the nonlinear stiffness storage unit 115 in the same manner as described above. The load force control unit 113 compares the angle converted from the estimated load based on the stiffness with the current motor angle, thereby compensating for the error between the stored stiffness and the stiffness of the actual machine. An angle correction value to be added or subtracted to or from the angle command value or the motor angle or both is derived and output so as to follow the load command value. Here, the motor angle is not an angle that wraps at a constant cycle like an electrical angle or a mechanical angle, but indicates an integrated angle of how much the motor has rotated.

The position control unit 111 derives a motor drive amount for causing the motor angle of the actual machine to follow the angle command value. The aforementioned angle correction value is applied to either or both of the angle command value and the motor angle as required. 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.

As a non-illustrated element, for example, in the load force control unit 113, when a relatively large angle correction value is determined and a variable overflow or underflow may occur in the subsequent calculation process, the angle correction value is reset; It is preferable to reset the internal calculation value of the position control unit 111 so that an inappropriate motor driving amount is not derived by resetting the angle correction value.

<<Estimated Stiffness of Nonlinear Stiffness Storage Unit 115>>
4A to 4E show the nonlinear stiffness (pressure increase characteristic, pressure reduction characteristic) when the linear motion mechanism 520 having the transmission mechanism 580 in FIG. 2 is applied, and the nonlinear stiffness storage unit 115 in FIG. Fig. 3 shows an example of stiffness correlation (actuator load vs. motor rotation amount characteristic). A solid line indicates pressure increase characteristics during pressure increase, a dashed line indicates pressure reduction characteristics during pressure reduction, and a dotted line indicates stiffness correlation stored in the nonlinear stiffness storage unit 115 .

FIGS. 4A to 4E also show the gradient of the motor rotation amount change (motor rotation amount change gradient) with respect to the actuator load (or linear motion load). If a discontinuous point is defined as a point where the motor rotation amount change gradient or the vice versa of the actuator load change gradient with respect to the motor rotation amount changes discontinuously, in this embodiment, in the pressure increase characteristic and the pressure decrease characteristic, There are two points of discontinuity in rigidity, counting from the lowest actuator load. It is a discontinuous point due to deformation such as the deformation limit of the spring member (elastic member) of the 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 Some stiffness properties may have properties that do not have a second discontinuity.

In general, the nonlinear stiffness during pressure increase and decompression has nonlinearity that does not match during pressure increase and decompression (hysteresis characteristic), and the tendency of the discrepancy varies 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 on the pressure increase side and the pressure decrease side are different in the motor rotation amount change gradient with respect to the actuator load shown in the figure, it is difficult to clearly grasp in advance what kind of rigidity it exhibits. .

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, in the stiffness correlation in the nonlinear stiffness storage unit 115, in the interval from F1a to F2a, the motor rotation amount change gradient on the pressure reduction side is adopted, and the discontinuity point of F2a on the pressure reduction side is adopted as the discontinuity point. do. 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 between the rigid phases may be a discontinuity point at a load that is sufficiently closer to F2a than F1a. A slightly larger load may be set.

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 stiffness correlation in the nonlinear stiffness storage unit 115 adopts the decompression side motor rotation amount change gradient in the section from F4a to F3a, and has a discontinuity point of F4a on the decompression side. Adopt a trait. 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 between the rigid phases may be a discontinuity point at a load 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. is 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, as the stiffness correlation, preferably, in the section from F2b to F1b, the motor rotation amount change gradient on the pressure increasing side is adopted, and the discontinuity point of F1b on the pressure increasing side is adopted as the discontinuity point. The discontinuity point between the rigid phases may be a discontinuity point at a load sufficiently closer to F1b than F2b, or the discontinuity point is slightly larger than F1b in consideration of the variation in characteristics of each individual actuator and aging. You can also set the load. Note that the stiffness correlation in the section from F4b to F3b, where a discontinuity 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 section 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 stiffness correlation in the nonlinear stiffness storage unit 115 adopts the pressure-increase-side motor rotation amount change gradient in the section from F3c to F4c, and the discontinuity point is the discontinuity point of F3c on the pressure-increase side. adopt a rigidity with The discontinuity point between the rigid phases may be a discontinuity point at a load sufficiently close to F3c rather than F4c, or the discontinuity point is slightly smaller than F3c, considering the variation in characteristics of each individual actuator, aging, etc. You can also set the load. Note that the stiffness correlation 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.

For FIG. 4D, stiffness correlations can be defined between actuator loads F1d to F2d in the same manner as F1b to F2b in FIG. 4B, and between actuator loads F3d to F4d in the same manner as F3c to F4c in FIG. 4C. FIG. 4E shows an example of stiffness correlation 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 stiffness correlation in FIG. 4A are closer to curved lines than straight lines.

<<Other Examples of Nonlinear Stiffness Storage 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 stiffness correlation in the nonlinear stiffness storage unit 115 based on the estimation results. In FIG. 5A, the nonlinear stiffness storage unit 115 includes a pressure increase stiffness storage unit 115a that stores the stiffness correlation during pressure increase, and a pressure decrease stiffness storage unit 115b that stores the stiffness correlation during pressure decrease. Further, it has a reference stiffness switching unit 115c that determines which of the stiffness correlations in the pressure increase stiffness storage unit 115a or the pressure decrease stiffness storage unit 115b is to be referred 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 reference stiffness switching section 115c refers to the stiffness correlation in the stiffness during pressure increasing storage section, and determines whether the motor is rotating toward the pressure decreasing side. When it is determined that the stiffness correlation is determined to be present, the stiffness correlation can be switched so that the stiffness correlation in the stiffness storage unit during reduced pressure is referred to. Alternatively, the reference stiffness 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. In the intermediate state, the stiffness correlation obtained by combining the stiffness correlations at the time of pressure increase and at the time of pressure reduction at a predetermined ratio may be referred to. Further, instead of the motor angle, it may be determined whether the stiffness correlation is referred to from the pressurization stiffness storage unit or the depressurization stiffness storage unit based on transition of the estimated load.

Now, in FIG. 5A, in addition to the nonlinear stiffness storage section, a stiffness parameter storage section 117 and a nonlinear stiffness estimation section 118 are provided in addition to the configuration of FIG. The stiffness parameter storage unit 117 stores the amount of rotation of the electric motor 510 and the estimated value when the load changes by a predetermined amount within a range including at least the load corresponding to the discontinuous point of the stiffness correlation stored in advance. 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.

The nonlinear stiffness estimator 118 estimates a discontinuity point of the correlation between the motor angle and the load in the stiffness correlation from the change history of the angle of the electric motor 510 and the estimated load, and calculates the estimated discontinuity. Update the stiffness correlation 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 unit. and a nonlinear stiffness 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.

ここで、g1(Fnl1) = g2(Fnl1), g2(Fnl2) = g3(Fnl2) を満足させるようg1(F), g2(F), g3(F)のうち何れか２つの関数の定数項は調整され、g1(F), g2(F), g3(F)のうち前記２つを除いた１つの関数の定数項Fcは後述のパラメータフィッティングの変数に用いる。 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 nonlinear stiffness calculator 118b derives stiffness correlations during pressure increase and pressure reduction based on the above calculation result of the convergence calculator 118a. After the derivation of the stiffness correlation is completed, the stiffness correlation in the nonlinear stiffness storage unit 115 is updated. The stiffness correlations in the pressure increase stiffness storage unit and the pressure decrease stiffness storage unit may be updated simultaneously, or may be updated separately at arbitrary timings. The functions of the nonlinear stiffness calculator 118b and the like may be used to create the stiffness correlations shown in FIGS. good.

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, the control device 100 compares the stored amount of change with the amount of change newly estimated after the storage, and if the amount of change changes more than a predetermined amount, the electric motor 510 in the stiffness correlation. and the load, and the stiffness correlation may be updated based on the determined discontinuity.

Note that, as factors not shown, the stiffness correlation is switched by the reference stiffness switching section 115c of the nonlinear stiffness storage section 115, and the stiffness correlation of the stiffness storage sections 115a and 115b during pressure increase and pressure reduction is updated. , it is preferable to provide a function for appropriately resetting the internal parameters so that the position control unit 111 does not calculate unnecessary motor drive commands.

5B, unlike FIG. 3 and the like, the nonlinear stiffness storage unit 115 stores the actuator stiffness (the stiffness relationship between the amount of rotation of the electric motor and the load) when the equivalent lead of the linear motion mechanism is large. A first stiffness storage section 115d, a second stiffness storage section 115e storing actuator stiffness in a state where the equivalent lead is small and the spring member is deformed, and a storage section 115e for storing the actuator stiffness in a state where the equivalent lead is small and the spring member has reached its deformation limit. and a third stiffness storage unit 115f in which the actuator stiffness is stored. In FIG. 5B, instead of using the stiffness correlation shown in FIG. 3 and the like, the three actuator stiffnesses are appropriately switched and referred to, so that the nonlinear stiffness correlation having two discontinuities as shown in FIG. have a similar effect. Therefore, the nonlinear stiffness storage unit 115 of FIG. 5B further includes a reference stiffness switching unit that switches and refers to any one of the first to third stiffness storage units. Also, in FIG. 5B, there is a discontinuity point estimation unit 119 .

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 that newly stores 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 one 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, the information on the discontinuous point is transmitted to the nonlinear stiffness estimator 115 .

For example, when it is determined that a discontinuity occurs while referring to the actuator stiffness in the first stiffness storage unit 115d in the pressure increasing direction, the reference stiffness switching unit 115c switches the second stiffness storage unit 115e. A transition to a state in which the actuator stiffness is referenced may be made. Further, in the pressure increasing direction, if it is determined that a point of discontinuity has occurred while referring to the actuator stiffness in the second stiffness storage section 115e, the actuator stiffness in the third stiffness storage section 115f is referred to. In the decompression direction, when it is determined that a discontinuity occurs while referring to the actuator stiffness of the second stiffness storage section 115e, the actuator stiffness of the first stiffness storage section 115d is changed to may transition to a state that refers to In the depressurization direction, if it is determined that a discontinuity has occurred while referring to the third stiffness storage unit 115f, the actuator stiffness of the second stiffness storage unit 115e may be referred to.

As a non-illustrated element, when the actuator stiffness is switched by the reference stiffness switching section 115c of the nonlinear stiffness storage section 115, a function to appropriately reset internal parameters so that the position control section 111 does not calculate unnecessary motor drive commands. 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.

It should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all modifications within the meaning and range of equivalents of the scope of the claims.

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 non-linear stiffness storage unit (storage unit)
115a Pressure increase stiffness storage unit 115b Pressure decrease stiffness storage unit 115c Reference stiffness switching unit 115d First stiffness storage unit 115e Second stiffness storage unit 115f Third stiffness storage unit 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)

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
each estimator for estimating the amount of rotation of the electric motor and the load applied by the linear motion mechanism;
Stores a stiffness correlation between the amount of rotation of the electric motor and the load at which the transition of the change gradient of one of the amount of rotation of the electric motor and the load that is not zero becomes discontinuous with respect to the change of the other. a storage unit;
a load controller that drives the electric motor so that the load estimated based on at least the stiffness correlation follows a target value;
having
Electric linear actuator. 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,
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,
In the stiffness correlation stored in the storage unit, the change gradient of the electric motor angle with respect to the load change on the side where the load is small from the first discontinuity point where the transition of the change gradient is discontinuous is the first discontinuity. including the first discontinuous point that is smaller than the change gradient of the electric motor angle on the side where the load is larger than the continuum point;
The transmission function having nonlinearity and the stiffness correlation 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 stiffness correlation is greater than the second shift load to the first shift load; near.
ii) said second shift load of said shift function is greater than said first shift load, and said first discontinuity point of said stiffness correlation is greater than said first shift load to said second shift load; near. 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,
According to the stiffness correlation stored in the storage unit, the change gradient of the electric motor angle with respect to the load change on the side where the load is small from the second discontinuity point where the transition of the change gradient is discontinuous is the second discontinuity. including the second point of discontinuity that is greater than the gradient of change in the angle of the electric motor on the side where the load is greater than the point of continuation;
The deformation characteristics and the stiffness correlation 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 stiffness correlation is greater than the first deformation load to the second deformation load; near.
ii) the second deformation load of the elastic member is greater than the first deformation load, and the second discontinuity of the stiffness correlation is greater than the first deformation load than the second deformation load; near. In the electric linear motion actuator according to any one of claims 1 to 3,
The non-linear stiffness storage unit includes a pressure increase stiffness storage unit storing the stiffness correlation when the pressure is increased when the load increases, and a pressure decrease stiffness storage unit storing the stiffness correlation when the load is decreased when the pressure is decreased. , a reference stiffness switching unit that determines which one of the stiffness phases of the pressure increase stiffness storage unit and the pressure decrease stiffness storage unit is to be referred to,
The reference stiffness switching unit refers to the stiffness phase in the pressure increasing stiffness storage unit when the motor is rotating on the pressure increasing side based on at least the transition of the motor angle or the estimated load transition, is rotating, switching between the stiffness phases so as to refer to the stiffness phases in the decompression stiffness storage unit;
Electric linear actuator. In the electric linear motion actuator according to claim 3,
The nonlinear stiffness storage unit stores a stiffness relationship between the amount of rotation of the electric motor and the load 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. a second rigidity storage unit that stores a rigidity relationship between the rotation amount of the electric motor and the load when the equivalent lead is small and the elastic member is deformed; and the equivalent lead is small and the elastic member is deformed. A third stiffness storage unit for storing a stiffness relationship between the amount of rotation of the electric motor and the load when the deformation limit is reached, and switching to any one of the first to third stiffness storage units for reference. It has a reference stiffness switching part with
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 rigid discontinuity exists when the gradient has changed,
The reference stiffness switching unit uses the stiffness relationships of the first to third stiffness storage units instead of using the stiffness correlation, and the change gradient comparison unit determines when a plurality of the discontinuous points exist. according to at least one of the plurality of points of discontinuity,
When it is determined that the discontinuity point occurs when the load changes in the pressure increasing direction in which the load is increased while referring to the stiffness relationship in the first stiffness storage unit, the stiffness relationship in the second stiffness storage unit is changed. See
When it is determined that the point of discontinuity has occurred when the pressure is changed in the direction of increasing pressure while referring to the stiffness relationship in the second stiffness storage unit, referring to the stiffness relationship in the third stiffness storage unit, When it is determined that the discontinuity has occurred when the pressure is changed in the direction of pressure reduction, the stiffness relationship in the first stiffness storage unit is referred to,
When it is determined that the discontinuity has occurred when the pressure changes in the direction of pressure reduction while referring to the stiffness relationship in the third stiffness storage unit, the stiffness relationship in the second stiffness storage unit is referred to.
Electric linear actuator. In the electric linear motion actuator according to any one of claims 1 to 4,
The control device controls the amount of rotation of the electric motor and the estimated amount of rotation of the electric motor when a predetermined amount of change occurs in the load within a range that includes at least the load corresponding to the discontinuity point of the stiffness correlation stored in advance. has a stiffness parameter storage unit that stores a change history with the applied load,
Further, the control device estimates a point of discontinuity in the correlation between the angle of the motor and the load in the stiffness correlation from the change history of the angle of the electric motor and the estimated load, and calculates the estimated discontinuity. a nonlinear stiffness estimator that updates the stiffness correlation based on points;
Electric linear actuator. In the electric linear motion actuator according to any one of claims 1 to 4,
The control device estimates and stores 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 compares the stored amount of change with the amount of change newly estimated after the storage, and if the amount of change changes more than a predetermined amount, the electric motor in the stiffness correlation. determining that a discontinuity has occurred between the angle of the motor and the load, and updating the stiffness correlation based on the determined discontinuity;
Electric linear actuator.

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