JP2019134551A - Electric actuator and electric brake device - Google Patents

Abstract

To provide an electric actuator and an electric brake device capable of improving NVH and enhancing control performance.SOLUTION: A control device 2 of an electric actuator comprises: an angle estimation unit 20a for estimating a motor angle; a load estimation function unit 19; a control arithmetic unit 23 for tracking controlling a control quantity relative to a given target value; and a mechanical coupling state estimation unit 24 that a transmission unit estimates a separation and contact state. The control arithmetic unit 23 has a first control arithmetic unit 23a for controlling the electric motor 4 according to a prescribed condition when it is estimated to be in a contact state, and a second control arithmetic unit 23b in which a magnitude of driving force of the electric motor 4 is calculated smaller than that of the first control arithmetic unit 23a when it is estimated to be a separation state.SELECTED DRAWING: Figure 2

Description

  The present invention relates to, for example, an electric actuator and an electric brake device mounted on a vehicle or the like, and relates to a technique capable of improving NVH and the like.

The following techniques have been proposed as an electric motor device and an electric actuator using the electric motor.
1. An electric actuator using a planetary roller mechanism and an electric motor (Patent Document 1).
2. An electric actuator using an electric motor, a linear motion mechanism, and a speed reducer (Patent Document 2).

JP 2006-194356 A JP-A-6-327190

  For example, in an electric linear actuator using an electric motor and a speed reducer as in Patent Document 1, a controller design in which the moment of inertia of the electric linear actuator is extremely important when performing control design for positioning control. It becomes a parameter. At this time, the moment of inertia is mainly the sum of the moments of inertia of the inertial bodies such as the motor rotor, gears, and the rotation shaft of the linear motion mechanism. Generally, the gear mechanism has a predetermined amount of backlash, When the gears are positioned on each other, the gears are not coupled to each other, and the moment of inertia can be changed equivalently to that of only the motor rotor.

  For example, in the case of applying a linear load, such as an electric brake device using the electric linear actuator of Patent Document 1, the larger the linear load, the more the gear always keeps in contact with the tooth surface on one side, and the moment of inertia Becomes equivalent to the moment of inertia of the entire actuator. On the other hand, the smaller the linear load (especially when the load is zero), the more easily the tooth surface of the gear becomes non-contact, and the moment of inertia temporarily becomes equivalent to the moment of inertia of the motor rotor only due to the backlash. .

  Electric brake devices are required to have a high-speed response and high control accuracy in order to perform wheel speed control of an antilock brake system (abbreviation: ABS) and the like with high accuracy. However, if a controller that exhibits high-speed and high-precision controllability in consideration of the inertial moment of the entire actuator is designed, the control system becomes unstable when the gearwheel is in a non-contact state during the backlash and the inertial moment decreases. It may become. When this unstable state occurs, the motor mainly vigorously swings between the backlashes, and repeatedly collides with the tooth surfaces on both sides of the gear, so that NVH (Noise, Vibration, There is a case in which a problem that Harshness) is extremely deteriorated or a problem that power consumption is increased by swinging the motor may occur.

As a measure for reducing the influence of the backlash, for example, when a structure such as a scissors gear is used, an increase in manufacturing cost and mounting space may be a problem. Further, when a method of adjusting the backlash amount using a spacer or the like is used, assembly may become difficult and an increase in manufacturing cost may be a problem.
Alternatively, when the control design is performed in consideration that the moment of inertia can be only the motor rotor, the responsiveness when the gear contacts and the moment of inertia becomes equivalent to the entire actuator is significantly reduced. In other words, in the case of an electric brake device, there is a case where the performance degradation of the ABS or the like mainly becomes a problem due to a decrease in responsiveness when the brake is applied.

  Alternatively, when backlash is modeled and control or the like for a non-linear control target is used, the calculation load increases, and a cost increase due to the use of a high-speed calculator may be a problem. Further, a high-speed computing unit generally has a large steady power consumption. For example, in an electric brake device that can be in a standby state where a lot of travel time does not operate an actuator, the power consumption of the computing unit may be a problem.

  An object of the present invention is to provide an electric actuator and an electric brake device capable of improving NVH and improving control performance.

The electric actuator according to the present invention transmits the electric motor 4 and the driving force of the electric motor 4 via a transmission unit having a play in which a contact state and a separation state are generated by switching between forward and reverse operations. In the electric actuator including the power transmission mechanisms 5 and 6 and the control device 2 for controlling the electric motor 4,
The control device 2
An angle estimation unit 20a for estimating a motor angle of the electric motor 4,
A load estimation function unit 19 that estimates a load applied by the driving force of the electric motor 4 via the power transmission mechanisms 5 and 6;
A control calculation unit 23 that controls the estimated value of the load or the motor angle as an operation amount, and follows a control amount that is the estimated value of the load or the motor angle with respect to a given target value;
A mechanical coupling that estimates that the transmission unit is in a separated state when the estimated value of the load is smaller than a predetermined value, and that the transmission unit is in a contact state when the estimated value of the load is larger than a predetermined value A state estimation unit 24,
The control calculation unit 23
A first control calculation unit 23a that controls the electric motor 4 according to a predetermined condition when the mechanical coupling state estimation unit 24 estimates that the transmission unit is in a contact state;
A second control calculation in which the magnitude of the driving force of the electric motor 4 is calculated smaller than that of the first control calculation unit 23a when the mechanical coupling state estimation unit 24 estimates that the transmission unit is in the separated state. Part 23b.
The predetermined values and the predetermined conditions are values and conditions arbitrarily determined by design, etc., and are determined by obtaining appropriate values and conditions by, for example, one or both of testing and simulation. It is done.

  According to this configuration, the control calculation unit 23 uses the estimated value of the load (referred to as “estimated load”) or the estimated value of the motor angle as the operation amount, and the estimated value of the load or the motor angle with respect to the target value. An operation amount for causing a certain control amount to follow the target value is determined. The mechanical coupling state estimation unit 24 estimates whether the transmission unit is in the separated state or the contact state according to the estimated load.

When the transmission unit is estimated to be in the contact state, the control calculation unit 23 enables the first control calculation unit 23a and controls the electric motor 4 according to the predetermined condition. In this case, high-speed and high-precision controllability can be exhibited in consideration of the moment of inertia of the entire electric actuator.
On the other hand, when the transmission unit is estimated to be in the separated state, the control calculation unit 23 activates the second control calculation unit 23b in which the driving force of the electric motor 4 is calculated smaller than the first control calculation unit 23a. And In this case, it is possible to perform a control calculation based on, for example, only the motor inertia in a state where the load is easily affected by backlash or the like and is low. Therefore, for example, it is possible to suppress the motor vibration caused by the equivalent inertia change between the backlashes and improve the NVH.

When the absolute value of the deviation between the target value of either the load or the motor angle derived from a given command input and the control amount is smaller than a predetermined value, the mechanical coupling state estimation unit 24 The transmission unit may be estimated to be in a separated state, and the transmission unit may be estimated to be in a contact state when the absolute value of the deviation is larger than a predetermined value.
Each of the determined values is a value arbitrarily determined by design or the like, and is determined by obtaining an appropriate value by one or both of testing and simulation, for example.

  When the load is small and the motor angle deviation is small, for example, there is a high possibility that the operation is performed in the middle of the backlash. Therefore, the operation during the backlash is assumed in advance and the operation is switched to the second control calculation unit 23b. According to this configuration, when the absolute value of the deviation is smaller than a predetermined value, it is estimated that the transmission unit is in the separated state, and the control unit 23b is switched to the second control calculation unit 23b. By doing so, it is possible to prevent the increase in NVH and the decrease in controllability due to the vibration of the response due to the equivalent moment of inertia of the electric actuator DA being reduced during backlash and the contact surface of the transmission portion being separated.

The control device 2 includes a disturbance estimation unit 28 that estimates a disturbance applied to the electric motor 4 including a reaction force to the driving force of the electric motor 4.
The mechanical coupling state estimation unit 24 has a function of storing an estimation result estimated that the transmission unit is in a contact state or a separated state, and the disturbance estimation is performed in a situation where the stored estimation result is a contact state. When it is estimated that a disturbance having a magnitude equal to or larger than the magnitude determined in the same direction as the driving force of the electric motor 4 is applied as the disturbance estimated by the unit 28, the mechanical coupling state estimation unit 24 displays the estimation result. It may have a function of making a transition from the contact state to the separated state.
The same direction is a torque direction when based on a motion in a rotating coordinate system, and is a moving direction of a linear motion member in the case of a linear motion via a linear motion mechanism, for example.
The determined size is a size arbitrarily determined by design or the like, and is determined by obtaining an appropriate size by, for example, one or both of testing and simulation.

  According to this configuration, when the load is zero or small, the disturbance applied to the electric motor 4 is mainly a frictional force, and basically a force that inhibits rotation acts. Under such circumstances, it is estimated that a disturbance is applied in the same direction as the driving force of the electric motor 4 mainly when the motor inertia is lower than expected. From this, it can be determined that the power transmission mechanism has entered during backlash, so that it is possible to appropriately switch to the second control calculation unit 23b, and the response can be prevented from being vibrated.

When the control device 2 performs follow-up control of the control amount with respect to the target value, the control device 2 determines the output torque of the electric motor 4 or a value depending on the output torque, and the angular acceleration of the electric motor 4. A function to estimate,
The mechanical coupling state estimation unit 24 has a function of storing an estimation result obtained by estimating that the transmission unit is in a contact state or a separated state, and is estimated in a situation where the stored estimation result is a contact state. When it is estimated that the magnitude of the angular acceleration is larger than a predetermined value, the mechanical coupling state estimation unit 24 may have a function of causing the estimation result to transition from the contact state to the separated state. .
Examples of the value depending on the output torque include current.
The determined value is a value arbitrarily determined by design or the like, and is determined by obtaining an appropriate value by one or both of testing and simulation, for example.

  According to this configuration, the upper limit acceleration that assumes the inertia of the entire electric actuator is exceeded mainly when the equivalent moment of inertia is reduced. From this, it can be determined that the intermediate state of the backlash of the power transmission mechanism has occurred, so that it is possible to appropriately switch to the second control calculation unit 23b, and the response can be prevented from becoming oscillating.

The control device 2 detects that the deviation between the target motor angle that is the target value and the estimated angle that is the estimated value of the motor angle has changed from positive to negative or from negative to positive. Part 30,
The mechanical coupling state estimation unit 24 has a function of storing an estimation result in which the transmission unit is estimated to be in a contact state or a separated state, and in the situation where the stored estimation result is a contact state, When the transition from positive to negative or negative to positive occurs a plurality of times within a predetermined time, the mechanical coupling state estimation unit 24 has a function of transitioning the estimation result from the contact state to the separated state. There may be.
The transition of the deviation from positive to negative or from negative to positive is called “zero crossing”.
The predetermined time is arbitrarily determined by design or the like, and is determined by obtaining an appropriate time by, for example, one or both of testing and simulation.

  According to this configuration, when the equivalent inertia is reduced only to the motor rotor due to the effect of backlash and the response becomes oscillating, the equivalent inertia is high-frequency zero crossing compared to the case of the entire electric actuator. Occur. For this reason, since it can be determined that the intermediate state of the backlash of the power transmission mechanism has occurred with this configuration, it is possible to appropriately switch to the second control calculation unit 23b, and the response can be prevented from being vibrated.

The mechanical coupling state estimation unit 24 is configured to determine whether the transmission unit is in a contact state under a condition for determining whether the transmission unit is in the separation state or the contact state, and the transmission unit is in a separation state. A second threshold different from the first threshold,
In the intermediate state between the first and second threshold values, the control calculation unit 23 emphasizes the first control calculation unit 23a when the estimation result of the mechanical coupling state estimation unit 24 is close to the contact state. When the estimation result is close to the separated state, the second control calculation unit 23b may include a control switching unit 23c that is emphasized.

  According to this configuration, the control switching unit 23c smoothly switches between the first and second control calculation units 23a and 23b, so that even when the switching operation is not performed as expected due to the influence of actuator characteristic fluctuation or the like, the control switching unit 23c Conversely, it is possible to prevent the response from being vibrated due to the influence of switching. Examples of the case where the switching operation is not as expected include cases where the switching timing is shifted and excessive switching occurs.

  The electric brake device 1 according to the present invention includes an electric actuator DA according to any one of the above, a friction material 9 operated by the electric actuator DA, and a brake rotor that generates a braking force by contact with the friction material 9. 8 and. According to the electric brake device 1, since any one of the electric actuators DA is provided, NVH can be improved and control performance can be improved.

  The electric actuator according to the present invention is a power transmission that transmits an electric motor and a driving force of the electric motor via a transmission unit having a play in which a contact state and a separation state are generated by switching between a forward operation and a reverse operation. An electric actuator comprising a mechanism and a control device that controls the electric motor, wherein the control device includes an angle estimation unit that estimates a motor angle of the electric motor, and a driving force of the electric motor causes the power transmission mechanism to A load estimation function unit that estimates a load acting through the control unit, and a control amount that is an estimated value of the load or the motor angle with respect to a given target value, with the estimated value of the load or the motor angle as an operation amount A control calculation unit that performs tracking control, and when the estimated value of the load is smaller than a predetermined value, the transmission unit is in a separated state, and the estimated value of the load is determined. A mechanical coupling state estimation unit that estimates that the transmission unit is in a contact state when the transmission unit is larger, and the control calculation unit is estimated by the mechanical coupling state estimation unit that the transmission unit is in a contact state A first control calculation unit that controls the electric motor according to a predetermined condition; and when the mechanical coupling state estimation unit estimates that the transmission unit is in a separated state, the magnitude of the driving force of the electric motor is And a second control calculation unit that is calculated smaller than the first control calculation unit. Therefore, it is possible to improve NVH and improve control performance.

  An electric brake device according to the present invention includes any one of the electric actuators described above, a friction material operated by the electric actuator, and a brake rotor that generates a braking force by contact with the friction material. Therefore, NVH can be improved and control performance can be improved.

It is a figure showing roughly the electric brake equipment concerning the embodiment of this invention. It is a block diagram of a control system of an electric actuator of the electric brake device. It is a block diagram which shows the structural example of the control apparatus of the same electric actuator. It is a block diagram of the control system of the electric actuator which concerns on other embodiment of this invention. It is a block diagram which shows the structural example of the control apparatus of the electric actuator which concerns on further another embodiment of this invention. It is a block diagram which shows the structural example of the control apparatus of the electric actuator which concerns on further another embodiment of this invention. It is a block diagram which shows the structural example of the control apparatus of the electric actuator which concerns on further another embodiment of this invention. It is a block diagram which shows the structural example of the control apparatus of the electric actuator which concerns on further another embodiment of this invention. It is a block diagram of the control system of the electric actuator which concerns on further another embodiment of this invention.

An electric brake device according to an embodiment of the present invention will be described with reference to FIGS. This electric brake device is mounted on a vehicle, for example.
As shown in FIG. 1, the electric brake device 1 includes an electric actuator DA and a friction brake BR. First, the structure of the electric actuator DA and the friction brake BR will be described.

<Structure of electric actuator DA and friction brake BR>
As shown in FIGS. 1 and 2, the electric actuator DA includes a linear actuator main body AH, a power supply device 3, and a control device 2 described later. The linear motion actuator main body AH includes an electric motor 4, a linear motion mechanism 6 and a speed reducer 5, which are power transmission mechanisms, a parking brake device 7, an angle sensor Sa, and a load sensor Sb.

As shown in FIG. 1, the electric motor 4 is composed of, for example, a permanent magnet type synchronous motor. When a permanent magnet type synchronous motor is applied as the electric motor 4, it is suitable for space saving, high efficiency and high torque.
The friction brake BR is provided on each wheel of the vehicle. The friction brake BR includes a brake rotor 8 that rotates in conjunction with the wheels, and a friction material 9 that contacts the brake rotor 8 and generates a braking force. The friction material 9 is operated by an electric actuator DA. It is possible to use a mechanism in which the friction material 9 is operated by the actuator body AH of the electric actuator DA and pressed against the brake rotor 8 to generate a braking force by the frictional force. As the friction brake BR in this example, a disc brake device using a brake rotor 8 which is a brake disc and a caliper (not shown) is applied, but a drum brake device using a drum and a lining may be used.

  The speed reducer 5 is a mechanism that decelerates the rotation of the electric motor 4, and includes a primary gear 12, an intermediate gear 13, and a tertiary gear 11 that are transmission units. In this example, the speed reducer 5 decelerates the rotation of the primary gear 12 attached to the rotor shaft 4 a of the electric motor 4 by the intermediate gear 13 and transmits it to the tertiary gear 11 fixed to the end of the rotating shaft 10. Possible parallel gears are used. The transmission unit has a play in which a contact state and a separated state are generated by switching between forward and reverse operations.

  The linear motion mechanism 6 is a mechanism for converting the rotational motion output from the speed reducer 5 into a linear motion of the linear motion portion 14 by a feed screw mechanism and bringing the friction material 9 into contact with and separated from the brake rotor 8. The linear motion part 14 is supported so as to be free of rotation and movable in the axial direction indicated by the arrow A1. A friction material 9 is provided on the outboard side end of the linear motion portion 14. By transmitting the rotation of the electric motor 4 to the linear motion mechanism 6 via the speed reducer 5, the rotational motion is converted into a linear motion, which is converted into the pressing force of the friction material 9 to generate a braking force. . In the state where the electric brake device 1 is mounted on the vehicle, the outer side in the vehicle width direction of the vehicle is referred to as the outboard side. The center side in the vehicle width direction of the vehicle is called the inboard side.

  For example, a linear solenoid is applied as the actuator 16 of the parking brake mechanism 7. The locking member 15 is advanced by the actuator 16 and is locked by being fitted into a locking hole (not shown) formed in the intermediate gear 13, and the parking gear is locked by prohibiting the rotation of the intermediate gear 13. To. By releasing the lock member 15 from the locking hole, the rotation of the intermediate gear 13 is allowed and the unlocked state is established.

  As shown in FIG. 2, the angle sensor Sa detects the rotation angle (motor angle) of the electric motor 4. As the angle sensor Sa, for example, a resolver or a magnetic encoder is preferably used because it is highly accurate and reliable, but various sensors such as an optical encoder may be used. Instead of using the angle sensor Sa, in the control device 2 to be described later, angle sensorless estimation that estimates the motor angle from the relationship between the voltage and current of the electric motor 4 can be used.

  The load sensor Sb detects the axial load of the linear motion mechanism 6. As the load sensor Sb, for example, a magnetic sensor, a strain sensor, a pressure sensor, or the like that detects displacement or deformation of a predetermined member to which the load of the linear motion mechanism 6 acts can be used. Instead of using the load sensor Sb, the control device 2 may perform the load sensorless estimation from the motor angle and the electric brake device rigidity, the motor current, the electric actuator efficiency, or the like. Alternatively, for example, other external sensors such as a wheel torque of a wheel on which a brake is mounted or a sensor for detecting a longitudinal force of a vehicle on which the electric brake device 1 (FIG. 1) is mounted may be used. In addition, various sensors such as a thermistor may be separately provided according to requirements.

<Configuration of control device 2>
FIG. 2 is a block diagram of a control system of the electric actuator DA of this electric brake device. For example, a control device 2 and an actuator main body AH corresponding to each wheel are provided. Each control device 2 controls a corresponding electric motor 4. Connected to each control device 2 is a DC power supply device 3 and a host ECU 17 which is a host control means of each control device 2. The power supply device 3 supplies power to the electric motor 4 and the control device 2. As the power supply device 3, for example, a low voltage (for example, 12V) battery of a vehicle on which the electric brake device 1 (FIG. 1) is mounted can be applied.

  For example, a vehicle integrated control unit (VCU) that controls the entire vehicle is applied as the host ECU 17. The host ECU 17 has an integrated control function of each control device 2. The host ECU 17 is provided with a brake command means 17a, and this brake command means 17a gives each control device 2 an output of a sensor that changes in accordance with an operation amount of a brake operation means (not shown) as a command value. The brake command means 17a may be the brake operation means itself, or it is automatically commanded without depending on the operation of the brake operation means from information on the state of the vehicle and various sensors such as an autonomous driving vehicle. It is also possible to obtain and output a value.

  Each control device 2 includes various control calculators that perform control calculations and a motor driver 18. The various control arithmetic units are configured by, for example, a processor such as a microcomputer, an arithmetic unit such as an FPGA or an ASIC, and a peripheral circuit. The various control calculators include a load estimator 19, a motion state estimator 20, a current estimator 21, a target value calculator 22, a control calculator 23, and a mechanical coupling state estimator 24 as load estimation function units.

The load estimator 19 estimates a load (estimated load) on which the driving force of the electric motor 4 acts via the speed reducer 5 and the linear motion mechanism 6 from the output of the load sensor Sb. Alternatively, as described above, the load estimator 19 may perform load sensorless estimation without using the load sensor Sb.
The motion state estimator 20 estimates the rotational motion state of the electric motor 4 from the output of the angle sensor Sa. The motion state estimator 20 includes an angle estimator 20a and an angular velocity estimator 20b.

  The angle estimation unit 20a has a function of estimating a motor angle (estimated angle) used for control calculation from the output of the angle sensor Sa. When using a sensor that detects a predetermined angle region as one cycle, such as a resolver or an encoder, as the angle sensor Sa, the angle estimation unit 20a estimates the rotor phase of the electric motor 4 from the output of the angle sensor Sa. Also good. The angular velocity estimation unit 20b may estimate the differential value of the rotor phase or position as the angular velocity.

  The motion state estimator 20 may estimate the linearly converted position, speed, etc., for example, via a motion conversion coefficient such as an equivalent lead. Alternatively, as described above, an angle sensorless estimator that estimates the rotor phase or the electrical angular velocity from the voltage and current of the electric motor 4 without providing the angle sensor output, and estimates the angle or the angular velocity from the rotor phase or the like. Also good. Further, the state parameter may be, for example, a process of differentiating an angle to obtain an angular velocity, or a state estimation observer.

  The estimated angle may have a function of deriving a continuous angle by complementing a periodical operation of an angle that overlaps or underlaps at a predetermined period. For example, with respect to one cycle in angle sensor Sa or angle sensorless estimation such as a resolver, generally, when the load in the electric brake device is changed from zero to the maximum value, the electric motor 4 rotates by an amount corresponding to a plurality of cycles. The total rotation angle can be derived by performing complementation.

  The current estimator 21 has a function of estimating a current used for control calculation from the current sensor output. As the current sensor 25, for example, a sensor composed of an amplifier that detects the voltage across the shunt resistor, or a non-contact sensor that detects a magnetic flux around the current path of the phase current of the electric motor 4 can be used. As another configuration, for example, the current estimator 21 may be configured to detect a terminal voltage or the like of elements constituting the motor driver 18 or may be configured to estimate the motor phase current from the primary current. Alternatively, feedforward control can be performed based on characteristics such as resistance or inductance of the electric motor 4 in a current control function described later without providing any current sensor.

  The target value calculator 22 has a function of calculating a control target value from the output of a predetermined brake command means 17a. When the brake command means 17a is, for example, a brake pedal (brake operation means), the target value calculator 22 can calculate a target brake load (target value) as a target from the stroke amount of the brake pedal, etc. When is returned (separated), the target motor angle or linear motion position for operating the actuator main body AH to the predetermined standby position can be calculated.

  Alternatively, for example, when the host ECU 17 such as a vehicle integrated control unit (VCU) is provided with the brake command means 17a, the target value calculator 22 receives, for example, a friction coefficient, a brake effective diameter, Alternatively, the target brake load may be calculated via a predetermined conversion coefficient such as vehicle inertia, or the target brake load may be directly input from the host ECU 17.

  The control calculation unit 23 calculates an electric motor operation amount in the motor driver 18 described later so that the control amount follows the command value requested by the brake command means 17a. For example, the control calculation unit 23 may perform feedback control calculation for following the estimated load with respect to the target brake load when exerting a braking force, and corresponds to a predetermined brake standby position when releasing the brake. A feedback control calculation for following control of the estimated angle (or estimated position with respect to the target position) with respect to the target motor angle or the like to be performed may be performed.

  The control calculation unit 23 may have a calculation structure in which a plurality of minor feedback controls are provided in addition to load feedback control, for example, motor angle feedback control, angular velocity feedback control, and current feedback control are provided in a brake load control loop. The motor operation amount may be calculated by a single feedback control. In addition, feed forward control or the like can be used instead of a part or all of the feedback control, or can be used in combination as appropriate.

  The control calculation unit 23 includes a first control calculation unit 23a, a second control calculation unit 23b, and a control switching unit 23c. The first control calculation unit 23a performs control calculation assuming a case where a gear serving as a transmission unit from the motor rotor to the speed reducer 5 is in a contact state (coupled state). The second control calculation unit 23b performs control calculation assuming that a part or the whole of the gear serving as the transmission unit is in a separated state. The control switching unit 23c switches the first and second control calculation units 23a and 23b based on whether the gear serving as the transmission unit is in a contact state or in a separated state.

  For example, when the transmission unit (mechanical coupling unit) is in a contact state such that a tooth surface of a gear or the like of the speed reducer 5 is in contact, the inertia moment of the electric actuator DA is a motor to which a motor driving force is coupled. The sum of the moments of inertia of all the machine components such as the rotor, the speed reducer 5 and the linear motion mechanism 6 (however, the influence of the speed reduction is taken into consideration as appropriate). On the other hand, when the transmission unit is in a separated state, such as a backlash in the gear or the like, the inertia moment of the electric actuator DA is an inertia moment excluding the member from which the transmission unit is separated, and in the minimum case, the electric motor 4 It can only be a motor rotor. In other words, when the transmission unit is in the separated state, the moment of inertia can be relatively reduced as compared with the case where the transmission unit is in the contact state.

  By the way, when the calculation formula in the control calculation unit is constructed assuming that the transmission unit is in a contact state, the control band is expanded to a higher frequency region than expected due to the reduction of the moment of inertia accompanying the separation of the transmission unit. . At this time, there is a case where the control stability is lowered contrary to the speeding up of the control, and there is a possibility that problems such as a decrease in controllability and a deterioration in NVH occur due to the vibration of the operation. In addition, for example, when a calculation formula in the control calculation unit is constructed assuming that the transmission unit is in a separated state, the phase in the control characteristics is delayed due to an increase in the moment of inertia accompanying the contact of the transmission unit, and the control stability May decrease. In addition, the responsiveness may be lower than expected, and the braking distance may be adversely affected.

  With the configuration of the present embodiment, the first control calculation unit 23a that performs control calculation assuming that the transmission unit from the motor rotor to the speed reducer 5 is in contact with a part or the whole of the transmission unit is separated. By appropriately switching the second control calculation unit 23b that performs the control calculation assuming a state in the state by the control switching unit 23c, it is possible to solve the problem caused by the contact or separation of these transmission units.

  The mechanical coupling state estimation unit 24 has a function of estimating what state the transmission unit is in contact or separation. As an example, in other words, based on a general gear, the mechanical coupling state estimation unit 24 has a function of estimating what state the gear is in contact with or in the middle of the backlash. .

  The mechanical coupling state estimation unit 24 is based on the estimated load, for example, when the estimated load is zero or a low load state less than a predetermined value, the transmission unit is separated, and the estimated load is greater than or equal to a predetermined value May be a function of determining that the transmission unit is in contact. When the brake load is zero or low, the transmission portion is likely to be separated due to zero or extremely small pressure applied to the transmission portion by the reaction force. On the other hand, when a brake load is applied, the transmission unit is easily maintained in a contact state because there is a pressure applied by a reaction force.

  Therefore, the mechanical coupling state estimation unit 24 can estimate whether the transmission unit is in the separated state or the contact state based on the estimated load. At this time, since the reaction force, that is, the pressurization, may be zero due to the influence of the mechanical hysteresis even in a low load state where the brake load is not zero, as described above, even if the brake load is a low load state, It is preferable to estimate that separation may occur.

  The motor driver 18 controls the power supplied from the electric motor 4. The motor driver 18 constitutes a half bridge circuit using a switching element such as a field effect transistor (abbreviated as FET), and PWM control for determining a motor applied voltage based on an ON-OFF duty ratio of the switching element. If it is the structure which performs, it will become inexpensive and high performance. Or it can also be set as the structure which provides a transformer circuit etc. and performs PAM control. In addition, as a switching potential source for the H arm switch element that is connected to the positive side of the power supply device 3 in the half bridge circuit, charges are accumulated from a predetermined potential source when the L arm switch element is turned on. A charge circuit using a bootstrap capacitor that functions as a potential source applied to the gate when the H arm switch element is turned on may be provided, or a booster circuit such as a charge pump circuit may be provided separately.

<Configuration example of mechanical coupling state estimation unit>
FIG. 3 shows a configuration example of the mechanical coupling state estimation unit 24 and the control calculation unit 23 shown in FIG. In FIG. 3, the mechanical coupling state estimation unit 24 determines whether the transmission unit is in a contact state or a separation state based on the result of the estimated load, and switches the control calculation unit 23 based on this determination. Show.

  When the actuator load is large, the transmission portion of the electric actuator is generally kept in contact with the reaction force against the load. On the other hand, when the load is small, the reaction force does not occur or is very small.For example, in the situation where the direction of the motor torque is reversed, the transmission unit does not contact the forward or reverse tooth surface. Can be. Therefore, the mechanical coupling state estimation unit 24 can determine that the transmission unit is in the separated state when the load is smaller than the predetermined value, and can determine that the transmission unit is in the contact state when the load is larger than the predetermined value.

  In the determination of the separation and the contact in the mechanical coupling state estimation unit 24, an intermediate state determination may be provided between the separation and the contact. That is, for example, in a load, a first threshold value that is determined to be a separation and a second threshold value that is determined to be a contact are provided, and the separation and the contact are continuous between the first threshold value and the second threshold value. It is good also as the process which switches to. In the intermediate state, the control calculation unit 23 emphasizes the first control calculation unit 23a when the estimation result of the mechanical coupling state estimation unit 24 approaches the contact state, and the second calculation unit when the estimation result approaches the separation state. The control calculation unit 23b includes a control switching unit 23c. Thereby, even when an error occurs between the state of the transmission unit in the actual actuator operation and the coupling state estimation result, it is possible to prevent the occurrence of chattering or the like at the time of control switching. Or in order to make it simpler processing, it is good also as binary switching based on the size of a predetermined threshold.

  The control calculation unit 23 switches the first and second control calculation units 23a and 23b that perform control calculation based on the target motor angle and the estimated motor angle, and switches the first and second control calculation units 23a and 23b. 26, and a control switching unit 23c that performs switching by means of H.26. Each of the first and second control calculation units 23a and 23b performs follow-up control on a control amount that is an estimated motor angle with respect to a given target motor angle (target value). The first and second control calculation units 23a and 23b may control the load as an input instead of the motor angle, or may include both of them. Further, the switch 26 shown in FIG. 3 may generate not only binary switching but also an intermediate state thereof. Furthermore, a third and subsequent control operation units may be provided.

<About the effects>
According to the electric actuator DA and the electric brake device 1 described above, when the transmission state is estimated by the mechanical coupling state estimation unit 24, the control calculation unit 23 activates the first control calculation unit 23a. The electric motor 4 is controlled. In this case, high-speed and high-precision controllability can be exhibited in consideration of the moment of inertia of the entire electric actuator.
On the other hand, when the transmission unit is estimated to be in the separated state, the control calculation unit 23 activates the second control calculation unit 23b in which the driving force of the electric motor 4 is calculated smaller than the first control calculation unit 23a. And In this case, it is possible to perform a control calculation based on, for example, only the motor inertia in a state where the load is easily affected by backlash or the like and is low. Therefore, for example, it is possible to suppress the motor vibration caused by the equivalent inertia change between the backlashes and improve the NVH. Further, it is possible to suppress the electric motor 4 from swinging between the backlashes, and thus it is possible to suppress power consumption.

<About other embodiments>
In the following description, the same reference numerals are given to portions corresponding to the matters described in advance in the respective embodiments, and overlapping descriptions are omitted. When only a part of the configuration is described, the other parts of the configuration are the same as those described in advance unless otherwise specified. The same effect is obtained from the same configuration. Not only the combination of the parts specifically described in each embodiment, but also the embodiments can be partially combined as long as the combination does not hinder.

  FIG. 4 shows an example in which a reaction force estimation unit 19A, which is a load estimation function unit, is provided in the motion state estimator 20 without providing a load estimator in the configuration example of FIG. The reaction force estimation unit 19A may have a function of estimating the state amount estimated by the state estimation observer including the reaction force, for example, a disturbance observer based on the output difference between the control target model and the actual machine. Also good. At this time, for example, the control of the brake load may be a function of controlling the reaction force to be a predetermined value.

  As illustrated in FIG. 5, the mechanical coupling state estimation unit 24 determines the separation / contact state of the transmission unit using, for example, a deviation between a target motor angle that is a target value and an estimated motor angle that is a control amount. May be. When the absolute value of the deviation between the target motor angle and the estimated motor angle is small, a situation in which the direction of torque is reversed to cause the estimated motor angle to follow the target motor angle is likely to occur, that is, an intermediate state of backlash occurs. easy. On the other hand, when the absolute value of the deviation is large, the electric motor rotates in one direction to reduce the deviation so that the estimated motor angle follows the target motor angle for the time being.

  Therefore, the mechanical coupling state estimation unit 24 determines that the transmission unit is in the separated state when the absolute value of the deviation is smaller than a predetermined value, and transmits when the absolute value of the deviation is larger than the predetermined value. It can be determined that the part is in contact. When the motor angle deviation is relatively large, the electric motor continues to rotate in one direction so as to reduce the angle deviation, so that the transmission unit can be in contact, and when the angle deviation is relatively small, the angle deviation is zero. Alternatively, there is a high possibility that the electric motor changes the rotation direction in order to converge within the allowable range, and the transmission unit is easily separated. Therefore, the mechanical coupling state estimation unit 24 can estimate the separation / contact state of the transmission unit based on the angular deviation of the electric motor. In addition, it can replace with the deviation of the estimated motor angle of this figure, and a target motor angle, and can also use the deviation of an estimated load and a target load. Further, when the load is sufficiently large, it can be determined that the transmission unit is in contact with the reaction force of the load regardless of the magnitude of the deviation.

Therefore, a combined state estimation execution determination unit 27 that determines whether to estimate the separation / contact state based on the estimated load is provided in the mechanical connection state estimation unit 24, and when the estimated load is larger than a predetermined value, the contact state is determined. can do.
According to this configuration, when the absolute value of the deviation is smaller than a predetermined value, it is estimated that the transmission unit is in the separated state, and the control unit 23b is switched to the second control calculation unit 23b. By doing so, it is possible to prevent an increase in NVH and a decrease in controllability due to the vibration of the response because the equivalent inertia moment of the electric actuator becomes small during backlash and the contact surface of the transmission portion is separated.
At this time, instead of the example of FIG. 5, the determination of the separation / contact state based on the estimated load shown in FIG. 3 is used together, for example, the separation / contact state of the separation / contact state derived by adding or multiplying each other's determination results. The determination result may be used.

  FIG. 6 shows an example in which a disturbance generated by an external force in the electric motor is estimated and the separation / contact state is determined based on the estimated disturbance. In this example, the control device includes a disturbance estimation unit 28 that estimates a disturbance (estimated disturbance) applied to the electric motor including a reaction force against the driving force of the electric motor. The mechanical coupling state estimation unit 24 has a function of storing the estimation result of the separation / contact state of the transmission unit, and in a situation where the stored estimation result is a contact state, the estimated disturbance and the driving force of the electric motor When it is estimated that a disturbance greater than or equal to the magnitude determined in the same direction is applied, the mechanical coupling state estimation unit 24 has a function of causing the estimation result to transition from the contact state to the separated state. The estimated disturbance may be derived, for example, by a disturbance estimation observer based on an operation amount, a control amount, a motion equation of an electric actuator, or the like.

  When the load is small, it is considered that the electric motor disturbance is mainly caused by rotational resistance, sliding resistance, or resistance due to kinematic viscosity caused by frictional force. In other words, it is considered that the disturbance is mainly a disturbance force that reduces the motor torque. At this time, if a disturbance that increases the motor torque is estimated, in other words, if a larger angular acceleration occurs in the electric motor than is estimated by the equation of motion for a predetermined operation amount, the moment of inertia of the electric actuator decreases. It is thought to be due to.

That is, since the transmission portion is in the separated state in the backlash intermediate state, it can be determined that the separated / contact state is separated when the load is small and the estimated disturbance is the assist force. The determination based on the assist force may be determined based on the case where the estimated disturbance is an assist force larger than a predetermined value in order to exclude the influence of a motor torque error or the like.
In addition to the load shown in FIG. 6, for example, the deviation shown in FIG. 5 may be used in combination as a condition for determining that the separation / contact state has changed from separation to contact. That is, when the absolute value of the deviation is equal to or greater than a predetermined value, the separation / contact state may be determined to be a contact state for the reason described with FIG.

  According to the configuration shown in FIG. 6, when the load is zero or small, the disturbance applied to the electric motor is mainly a frictional force, and basically a force that inhibits rotation acts. Under such circumstances, it is estimated that a disturbance is applied in the same direction as the driving force of the electric motor, mainly when the motor inertia is lower than expected. From this, it can be determined that the power transmission mechanism has entered during backlash, so that it is possible to appropriately switch to the second control calculation unit 23b, and the response can be prevented from being vibrated.

FIG. 7 shows an example in which the angular acceleration of the electric motor is estimated and the separation / contact state is determined based on the estimated angular acceleration. The control device is provided with an angular acceleration estimator 29 for estimating the angular acceleration. The angular acceleration may be derived by, for example, differential of an estimated angle or a state estimation observer.
When the load is small, it is considered that the electric motor disturbance is mainly caused by rotational resistance, sliding resistance, or resistance due to kinematic viscosity caused by frictional force. In other words, it is considered that the disturbance is mainly a disturbance force that reduces the motor torque. At this time, if the absolute value of the motor angular acceleration is larger than the angular acceleration that can be generated with respect to the inertia moment of the entire electric actuator, it is considered that this is due to a decrease in the inertia moment of the electric actuator.

  In other words, since the transmission unit is in a state where the backlash is in an intermediate state, it can be determined that the separation / contact state is separated when the absolute value of the angular acceleration is greater than a predetermined value. The case where the absolute value of the angular acceleration is larger than a predetermined value is preferably, for example, a case where the magnitude of the angular acceleration that can be derived from a predetermined operation amount and a moment of inertia such as a motor torque is exceeded. Therefore, the maximum angular acceleration that can be generated may be exceeded. Further, the case where the magnitude of the angular acceleration is exceeded is preferably a threshold value in consideration of the influence of the motor torque error.

  Contrary to the above, a lower limit value (magnitude, positive or negative) of the angular acceleration is set based on the moment of inertia of the electric motor rotor and the electric motor torque, and the magnitude of the angular acceleration. It can also be determined that the transmission unit has contacted when the value becomes smaller than the lower limit. The angular acceleration may be a differential value of the angular velocity, or the angular velocity ahead of a predetermined time is estimated based on the moment of inertia and the motor torque, and the separation / contact of the transmission unit based on the acceleration after the predetermined time has elapsed. The state may be estimated. The predetermined time may be a time that is one cycle ahead of the control cycle, for example.

  FIG. 8 shows an example in which the zero crossing of the estimated motor angle with respect to the target motor angle is detected, and the separation / contact state is determined based on the detection. In this example, the control device includes a zero-crossing detector 30 that detects that the deviation between the target motor angle and the estimated motor angle (estimated angle) has changed from positive to negative or from negative to positive. The mechanical coupling state estimation unit 24 has a function of storing the estimation result of the separation / contact state, and in a situation where the stored estimation result is a contact state, the deviation transitions from positive to negative or from negative to positive. Is generated a plurality of times within a predetermined time, the mechanical coupling state estimation unit 24 has a function of transitioning the estimation result from the contact state to the separated state. In addition to FIG. 8, for example, in the case of controlling an extremely small load, zero crossing of the estimated load with respect to the target load may be used.

  If the contact state of the transmission part is separated and the moment of inertia decreases mainly to the motor rotor only, the operation amount based on the control calculation assumed for the moment of inertia of the entire electric actuator becomes excessive, and the specified command value The operation amount often chatters. At that time, zero crossing with a relatively short cycle occurs. Therefore, when the zero crossing cycle is shorter than a predetermined time, it can be determined that the separation / contact state is separation. Further, when the zero-crossing cycle is equal to or longer than a predetermined time, it can be determined as a contact state. In other words, when the transmission part is separated and the moment of inertia is reduced and control stability is reduced, zero crossing occurs in a short cycle that cannot be generated unless the moment of inertia is reduced. The state can be estimated.

  For any one or more of the mechanical coupling state estimation unit 24, the control switching unit 23 determines whether the transmission unit is separated for each estimation element and the threshold value for determining that the transmission unit is in contact. The second control calculation units 23a and 23b can be switched. At this time, even if the intermediate values of the plurality of threshold values are determined as the degree of separation or contact of the transmission unit, the degree of influence of the first and second control calculation units 23a and 23b is determined based on these degrees. Good. By performing smooth switching in this way, for example, it is possible to prevent NVH from deteriorating due to the switching operation itself.

According to this configuration, when the equivalent inertia is reduced only to the motor rotor due to the effect of backlash and the response becomes oscillating, the high-frequency zero crossing is reduced compared to the case of the entire electric actuator. Occur. For this reason, since it can be determined that the intermediate state of the backlash of the power transmission mechanism has occurred with this configuration, it is possible to appropriately switch to the second control calculation unit 23b, and the response can be prevented from being vibrated. In order to eliminate erroneous detection due to the influence of noise or the like, for example, only zero crossing exceeding a predetermined amplitude may be detected, and zero crossing within a predetermined period range has continuously occurred for a predetermined time or more. You may make a judgment.
The methods shown in FIGS. 3 and 5 to 8 may be used in combination as long as no contradiction occurs.

  FIG. 9 shows an example in which the electric steering apparatus is configured as a rotary actuator main body AH instead of the direct acting actuator main body AH, with respect to the configuration example of FIG. This example has substantially the same configuration as the configuration example of FIG. 2 except that a rotational torque load is handled instead of a direct acting load. For example, the torque sensor Sc may have a function of estimating torque from twisting of a steering rod or the like.

Each block diagram merely shows the concept of the functional configuration, and elements not shown are appropriately provided according to requirements. Each functional block is provided for convenience, and can be appropriately integrated or divided according to mounting convenience.
Each embodiment may be configured to be used together as appropriate within a range where no contradiction in function occurs. For example, the reaction force estimation unit 19A shown in FIG. 4 may be provided in the example of FIG. 2 and used for disturbance cancellation control or the like. Moreover, the connection form of each function is shown as an example, and can be changed within a range that does not hinder the function.

  In addition, it is possible to appropriately construct another application that basically follows the configuration of each figure. For example, the electric brake device shown in FIGS. 2 and 4 can be applied to an electric press device in which a press die or the like is connected to a linear motion mechanism. In the electric steering device shown in FIG. Application to an electric valve device or the like that connects a valve device or the like and controls the valve opening degree is also possible.

As the electric motor 4, for example, a DC motor using a brush, a reluctance motor not using a permanent magnet, an induction motor, or the like can be applied.
As the speed reducer 5, for example, a speed reducer such as a worm gear or a planetary gear may be used. Alternatively, when the load may be small as a requirement, a simple mechanical coupling system (speed reduction ratio≈1) that does not reduce speed may be used, or a speed increaser (speed reduction ratio <1) may be used.

  As the linear motion mechanism 6, various screw mechanisms such as a planetary roller screw and a ball screw, and various mechanisms that convert a rotational motion into a straight motion by tilting in the circumferential direction of the rotational axis, such as a ball ramp, can be used.

  As mentioned above, although the form for implementing this invention based on embodiment was demonstrated, embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 2 ... Control apparatus 4 ... Electric motor 5 ... Reduction gear 6 ... Linear motion mechanism 8 ... Brake rotor 9 ... Friction material 19 ... Load estimator (load estimation function part)
20a ... Angle estimation unit 23 ... Control calculation units 23a, 23b ... First and second control calculation units 23c ... Control switching unit 24 ... Mechanical coupling state estimation unit 28 ... Disturbance estimation unit 30 ... Zero crossing detection unit DA ... Electric Actuator

Claims (7)

An electric motor, a power transmission mechanism for transmitting the driving force of the electric motor via a transmission unit having play in which a contact state and a separation state are generated by switching between a forward operation and a reverse operation, and the electric motor is controlled An electric actuator comprising a control device for
The controller is
An angle estimation unit for estimating a motor angle of the electric motor;
A load estimation function unit that estimates a load applied by the driving force of the electric motor via the power transmission mechanism;
A control calculation unit that controls an estimated value of the load or the motor angle as an operation amount, and controls a control amount that is an estimated value of the load or the motor angle with respect to a given target value;
A mechanical coupling that estimates that the transmission unit is in a separated state when the estimated value of the load is smaller than a predetermined value, and that the transmission unit is in a contact state when the estimated value of the load is larger than a predetermined value A state estimation unit,
The control calculation unit is
A first control calculation unit that controls the electric motor according to a predetermined condition when the transmission unit is estimated to be in a contact state by the mechanical coupling state estimation unit;
A second control calculation unit in which the magnitude of the driving force of the electric motor is calculated to be smaller than that of the first control calculation unit when the transmission unit is estimated to be in the separated state by the mechanical coupling state estimation unit; Electric actuator having.   2. The electric actuator according to claim 1, wherein the mechanical coupling state estimator is an absolute value of a deviation between the target value of either a load or a motor angle derived from a given command input and the control amount. An electric actuator that estimates that the transmission unit is in a separated state when is smaller than a predetermined value, and estimates that the transmission unit is in a contact state when the absolute value of the deviation is larger than a predetermined value. The electric actuator according to claim 1 or 2, wherein the control device includes a disturbance estimation unit that estimates a disturbance applied to the electric motor, including a reaction force with respect to a driving force of the electric motor,
The mechanical coupling state estimation unit has a function of storing an estimation result estimated that the transmission unit is in a contact state or a separated state, and the disturbance estimation unit in a situation where the stored estimation result is a contact state When it is estimated that a disturbance having a magnitude equal to or greater than the magnitude determined in the same direction as the driving force of the electric motor is estimated as the disturbance estimated in step (b), the mechanical coupling state estimation unit separates the estimation result from the contact state. An electric actuator having a function of transition to a state. The electric actuator according to claim 1 or 2,
The control device has a function of determining an output torque of the electric motor or a value depending on the output torque, and a function of estimating an angular acceleration of the electric motor when the control amount is follow-up controlled with respect to the target value. And having
The mechanical coupling state estimation unit has a function of storing an estimation result in which the transmission unit is estimated to be in a contact state or a separated state, and is estimated in a situation where the stored estimation result is a contact state. When it is estimated that the magnitude of angular acceleration is greater than a predetermined value, the mechanical coupling state estimation unit has a function of causing the estimation result to transition from a contact state to a separated state. The electric actuator according to claim 1 or 2,
The control device is configured to detect that a deviation between a target motor angle that is the target value and an estimated angle that is an estimated value of the motor angle has changed from positive to negative or from negative to positive. Have
The mechanical coupling state estimation unit has a function of storing an estimation result estimated that the transmission unit is in a contact state or a separated state, and in a situation where the stored estimation result is a contact state, the deviation correction When the transition from negative to negative or negative to positive occurs a plurality of times within a predetermined time, the mechanical coupling state estimation unit has a function of transitioning the estimation result from the contact state to the separated state. The electric actuator according to claim 1 or 2,
The mechanical coupling state estimation unit is configured to determine whether the transmission unit is in a contact state in a condition for determining whether the transmission unit is in the separation state or the contact state, and the transmission unit is in a separation state. A second threshold that is presumed to be different from the first threshold,
In the intermediate state between the first and second threshold values, the control calculation unit emphasizes the first control calculation unit when the estimation result of the mechanical coupling state estimation unit approaches the contact state, and the estimation result is An electric actuator having a control switching unit in which the second control calculation unit is emphasized when approaching the separated state. An electric actuator according to any one of claims 1 to 6, a friction material operated by the electric actuator, and a brake rotor that generates a braking force by contact with the friction material. Electric brake device.

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