JP7017940B2 - Electric actuators and electric braking devices - Google Patents

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 or the like.

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

Japanese Unexamined Patent Publication No. 2006-19435 Japanese Unexamined Patent Publication No. 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 designing a control 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 body such as the motor rotor, the gear, and the rotating shaft of the linear motion mechanism. Generally, the gear mechanism has a predetermined amount of backlash and is in the middle of the backlash. When the gears are located in, the gears do not connect to each other, and the moment of inertia can change equivalently to that of the motor rotor only.

For example, when a linear motion load is applied, such as an electric brake device using an electric linear motion actuator of Patent Document 1, the larger the linear motion load, the more the gear always keeps in contact with the tooth surface on one side, and the moment of inertia. Is close 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 likely the tooth surface of the gear becomes non-contact, and the moment of inertia temporarily approaches the equivalent of the moment of inertia of the motor rotor only due to the effect of the backlash. ..

In order to control the wheel speed of the Antilock Brake System (abbreviation: ABS) with high accuracy, the electric brake device is required to have high-speed response and high control accuracy. However, if a controller that exhibits high-speed and high-precision controllability is designed in consideration of the moment of inertia of the entire actuator, the control system becomes unstable when the gears are in a non-contact state during the backlash and the moment of inertia drops. May be. When this unstable state occurs, the motor swings violently mainly between the backlashes and repeatedly collides with the tooth surfaces on both sides of the gear, resulting in NVH (Noise, Vibration,), which is a general term for noise, vibration, and riding comfort. Harshness) may be extremely deteriorated, or the power consumption may increase due to the vibration of the motor.

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 become a problem. Further, when a method of adjusting the backlash amount by using a spacer or the like is used, assembly may become difficult and an increase in manufacturing cost may become a problem.
Alternatively, when the control design is performed in consideration that the moment of inertia can be only the motor rotor in advance, the responsiveness when the gears come into contact and the moment of inertia becomes equivalent to the entire actuator is significantly reduced. In other words, the deterioration of the responsiveness when the brake is applied may cause a problem mainly in the performance deterioration of the ABS or the like.

Alternatively, when backlash is modeled and control for a non-linear control target is used, the calculation load increases, and the cost increase due to the use of a high-speed calculation unit may become a problem. Further, a high-speed arithmetic unit generally has a large steady power consumption, and for example, in an electric brake device which may be in a standby state in which the actuator is not operated for most of the traveling time, the power consumption of the arithmetic unit may become 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 and the like.

The electric actuator of 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 the operation in the forward direction and the reverse direction. In an electric actuator including a power transmission mechanism 5 and 6 and a control device 2 for controlling the electric motor 4.
The control device 2 is
The angle estimation unit 20a for estimating the motor angle of the electric motor 4 and the
A load estimation function unit 19 that estimates the load exerted by the driving force of the electric motor 4 via the power transmission mechanisms 5 and 6, and a load estimation function unit 19.
A control calculation unit 23 that uses the load or an estimated value of the motor angle as an operation amount and follows and controls a control amount that is an estimated value of the load or the motor angle with respect to a given target value.
When the estimated load value is smaller than the specified value, the transmission unit is in a separated state, and when the estimated load value is larger than the specified value, the transmission unit is estimated to be in the contact state. With 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 transmission unit is estimated to be in a contact state by the mechanical coupling state estimation unit 24.
A second control calculation in which the magnitude of the driving force of the electric motor 4 is calculated to be smaller than that of the first control calculation unit 23a when the transmission unit is estimated to be in a separated state by the mechanical coupling state estimation unit 24. It has a portion 23b.
The above-mentioned defined values and the above-mentioned defined conditions are values and conditions arbitrarily determined by design and the like, and are determined by obtaining appropriate values and conditions by, for example, either or both of test and simulation. Be 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 uses the load or the estimated value of the motor angle with respect to the target value. An operation amount for making a certain control amount follow the target value is determined. The mechanical coupling state estimation unit 24 estimates whether the transmission unit is in a separated state or a contact state according to the estimated load.

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

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

When the load is small and the motor angle deviation is small, for example, there is a high possibility that the operation will be in the middle of the backlash. Therefore, the operation in 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 the predetermined value, it is estimated that the transmission unit is in the separated state, and the unit 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 contact surface of the transmission portion being separated during the backlash, the equivalent moment of inertia of the electric actuator DA being reduced, and the response being oscillating.

The control device 2 has a disturbance estimation unit 28 that estimates a disturbance applied to the electric motor 4, including a reaction force with respect 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 in a contact state. When it is estimated that a disturbance of a magnitude or more 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 obtains the estimation result. It may have a function of transitioning from a contact state to a separated state.
The same direction is the torque direction when based on the motion in the rotating coordinate system, and is, for example, the moving direction of the linear motion member in the case of linear motion via a linear motion mechanism or the like.
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 a test and a 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 hinders rotation acts. Under such circumstances, it is presumed that the 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 rushed into the backlash, so that it is possible to appropriately switch to the second control calculation unit 23b, and it is possible to prevent the response from becoming oscillating.

The control device 2 has a function of determining the output torque of the electric motor 4 or a value depending on the output torque when the control amount is followed and controlled with respect to the target value, and the angular acceleration of the electric motor 4. Has a function to estimate,
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 is estimated in a situation where the stored estimation result is in a contact state. When the magnitude of the angular acceleration is estimated to be larger than a predetermined value, the mechanical coupling state estimation unit 24 may have a function of transitioning the estimation result from the contact state to the separated state. ..
Examples of the value depending on the output torque include current and the like.
The predetermined value is a value arbitrarily determined by design or the like, and is determined by obtaining an appropriate value by, for example, one or both of a test and a simulation.

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

The control device 2 detects zero crossing detection for detecting that the deviation between the target motor angle, which is the target value, and the estimated angle, which is the estimated value of the motor angle, has changed from positive to negative or from negative to positive. Has a unit 30
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 in a situation where the stored estimation result is in a contact state, the deviation of the deviation. When the transition from positive to negative or from 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 negative to positive is called "zero crossing".
The predetermined time is a time arbitrarily determined by design or the like, and is determined by obtaining an appropriate time by, for example, one or both of a test and a simulation.

According to this configuration, when the equivalent inertia is reduced only to the motor rotor due to the influence of backlash etc. and the response becomes oscillating, the equivalent inertia becomes high frequency zero crossing compared to the case of the entire electric actuator. Occur. Therefore, since it can be determined that the backlash intermediate state of the power transmission mechanism has occurred by this configuration, it is possible to appropriately switch to the second control calculation unit 23b, and it is possible to prevent the response from becoming oscillating.

The mechanical coupling state estimation unit 24 has a first threshold value for presuming that the transmission unit is in the contact state under the condition of determining whether the transmission unit is in the separation state or the contact state, and the transmission unit is in the separation state. A second threshold that is presumed to be in, and is 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 approaches the contact state. The second control calculation unit 23b may have a control switching unit 23c that is emphasized when the estimation result is close to the separation state.

According to this configuration, the control switching unit 23c smoothly switches between the first and second control calculation units 23a and 23b, so that control can be performed even when the switching operation is not as expected due to the influence of actuator characteristic fluctuations and the like. On the contrary, it is possible to prevent the response from becoming vibrating due to the influence of switching. Examples of cases where the switching operation is not as expected include cases where the switching timing is deviated, excessive switching occurs, and the like.

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

The electric actuator of the present invention transmits a power transmission through an electric motor and a transmission unit having a play in which a contact state and a separation state are generated by switching the operation in the forward direction and the reverse direction. In an electric actuator including a mechanism and a control device for controlling the electric motor, the control device has an angle estimation unit that estimates the motor angle of the electric motor, and the driving force of the electric motor controls the power transmission mechanism. A control amount that is an estimated value of the load or the motor angle with respect to a given target value, using the load estimation function unit that estimates the load acting through the device and the estimated value of the load or the motor angle as the operation amount. When the estimated value of the load is smaller than the specified value, the transmission unit is in a separated state, and when the estimated value of the load is larger than the specified value, the transmission unit is in a separated state. The control calculation unit includes a mechanical coupling state estimation unit that estimates that the motor is in contact, and the control calculation unit defines the electric motor when the transmission unit is estimated to be in contact by the mechanical coupling state estimation unit. When the transmission unit is estimated to be in a separated state by the first control calculation unit that controls according to the conditions and the machine coupling state estimation unit, the magnitude of the driving force of the electric motor is larger than that of the first control calculation unit. It has a second control calculation unit that is calculated small. Therefore, NVH can be improved and control performance can be improved.

The electric brake device of the present invention includes the electric actuator according to any one of the 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 which shows schematic the electric brake device which concerns on embodiment of this invention. It is a block diagram of the control system of the electric actuator of the electric brake device. It is a block diagram which shows the structural example of the control device of the 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 device of the electric actuator which concerns on still another Embodiment of this invention. It is a block diagram which shows the structural example of the control device of the electric actuator which concerns on still another Embodiment of this invention. It is a block diagram which shows the structural example of the control device of the electric actuator which concerns on still another Embodiment of this invention. It is a block diagram which shows the structural example of the control device of the electric actuator which concerns on still another Embodiment of this invention. It is a block diagram of the control system of the electric actuator which concerns on still another Embodiment of this invention.

The electric brake device according to the embodiment of the present invention will be described with reference to FIGS. 1 to 3. This electric braking 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 structures 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 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 comprises, 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 because it saves space, has high efficiency, and has high torque.
The friction brake BR is provided on each wheel of the vehicle. The friction brake BR has a brake rotor 8 that rotates in conjunction with the wheels, and a friction material 9 that comes into contact with the brake rotor 8 to generate braking force. The friction material 9 is operated by an electric actuator DA. A mechanism can be used 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 of 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 for reducing the rotation of the electric motor 4, and includes a primary gear 12, an intermediate gear 13, and a tertiary gear 11, which are transmission units, respectively. In this example, the speed reducer 5 decelerates the rotation of the primary gear 12 attached to the rotor shaft 4a of the electric motor 4 by the intermediate gear 13 and transmits the rotation 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 separation state are generated by switching the operation in the forward direction and the reverse direction.

The linear motion mechanism 6 is a mechanism that converts the rotary motion output by the speed reducer 5 into a linear motion of the linear motion portion 14 by the feed screw mechanism, and causes the friction material 9 to abut and separate from the brake rotor 8. The linear motion portion 14 is detented and is movably supported in the axial direction indicated by the arrow A1. A friction material 9 is provided at 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. .. With the electric brake device 1 mounted on the vehicle, the outside of the vehicle in the vehicle width direction is referred to as the outboard side. The center side of the vehicle in the width direction is called the inboard side.

As the actuator 16 of the parking brake mechanism 7, for example, a linear solenoid is applied. A parking lock state is achieved by advancing the lock member 15 by the actuator 16 and fitting it into a locking hole (not shown) formed in the intermediate gear 13 to lock the intermediate gear 13 and prohibiting the rotation of the intermediate gear 13. To. By disengaging the lock member 15 from the locking hole, the intermediate gear 13 is allowed to rotate and is brought into an unlocked state.

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, it is preferable to use a resolver or a magnetic encoder because of high accuracy and high reliability, but various sensors such as an optical encoder can also be used. Instead of using the angle sensor Sa, in the control device 2 described later, angle sensorless estimation that estimates the motor angle from the relationship between the voltage and the current of the electric motor 4 can also 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 the displacement or deformation of a predetermined member on 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 load sensorless estimation from, for example, the motor angle and the rigidity of the electric brake device, the motor current, the electric actuator efficiency, and the like. Alternatively, it may be another external sensor such as a sensor that detects the wheel torque of the wheel on which the brake is mounted or the front-rear force of the vehicle equipped with the electric brake device 1 (FIG. 1). In addition, various sensors such as thermistors may be separately provided according to the 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 the corresponding electric motor 4. A DC power supply device 3 and a higher-level ECU 17 which is a higher-level control means of each control device 2 are connected to each control device 2. The power supply device 3 supplies electric power to the electric motor 4 and the control device 2. As the power supply device 3, for example, a low voltage (for example, 12 V) battery of a vehicle equipped with the electric brake device 1 (FIG. 1) may be applied.

As the upper ECU 17, for example, a vehicle integrated control unit (Vehicle Control Unit, VCU) that controls the entire vehicle is applied. The upper ECU 17 has an integrated control function for each control device 2. The upper ECU 17 includes a brake command means 17a, and the brake command means 17a gives each control device 2 an output of a sensor that changes according to the operation amount of the brake operation means (not shown) as a command value. The brake command means 17a may be the brake operation means itself, or automatically commands from information such as the state of the vehicle and various sensors such as an autonomous driving vehicle, without depending on the operation of the brake operation means. It is also possible to obtain the value and output it.

Each control device 2 includes various control calculators that perform control calculations and a motor driver 18. The various control arithmetic units are composed of, for example, a processor such as a microcomputer, an arithmetic unit such as FPGA or ASIC, and peripheral circuits. 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 machine coupling state estimator 24 as load estimation function units.

The load estimator 19 estimates the 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 has an angle estimation unit 20a and an angular velocity estimation unit 20b.

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

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

With respect to the estimated angle, it may have a function of complementing the periodic motion of the angle that overlaps or overlaps in a predetermined cycle and derives a continuous angle. For example, when the load in the electric braking device is generally changed from zero to the maximum value for one cycle in the angle sensor Sa of a resolver or the like or the angle sensorless estimation, the electric motor 4 rotates 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 the current used for the control calculation from the current sensor output. As the current sensor 25, for example, a sensor including an amplifier that detects the voltage across the shunt resistance, a non-contact sensor that detects the magnetic flux around the energization path of the phase current of the electric motor 4, or the like can be used. As another configuration, the current estimator 21 may be configured to detect the terminal voltage or the like of the element or the like constituting the motor driver 18, or may be configured to estimate the motor phase current from the current on the primary side. Alternatively, feedforward control can be performed based on characteristics such as resistance or inductance of the electric motor 4 in the 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 the predetermined brake command means 17a. When the brake command means 17a is, for example, a brake pedal (brake operating means), the target value calculator 22 can calculate a target brake load (target value) from the stroke amount of the brake pedal or the like, and the brake pedal. When returned (released), the target motor angle or linear motion position for operating the actuator main body AH to a predetermined standby position can be calculated.

Alternatively, for example, when the upper ECU 17 such as the vehicle integrated control device (VCU) is provided with the brake command means 17a, the target value calculator 22 may, for example, obtain a friction coefficient, a brake effective diameter, etc. from commands such as vehicle deceleration and braking force. 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 upper ECU 17.

The control calculation unit 23 calculates the operation amount of the electric motor in the motor driver 18, which will be 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 a feedback control calculation for following and controlling the estimated load with respect to the target brake load when the braking force is exerted, and corresponds to a predetermined brake standby position when the brake is released. A feedback control calculation may be performed to follow and control the estimated angle (or the estimated position with respect to the target position) with respect to the target motor angle or the like.

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

Further, 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 a control calculation assuming that the gear, which is 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 a control calculation assuming that a part or the whole of the gear, which is the transmission unit, is in a separated state. The control switching unit 23c switches between the first and second control calculation units 23a and 23b based on whether the gear, which is the transmission unit, is in the contact state or the separated state.

For example, when the transmission portion (mechanical coupling portion) is in a contact state such that the tooth surface of the gear of the speed reducer 5 is in contact, the moment of inertia of the electric actuator DA is the motor to which the motor driving force is coupled. It is the sum of the moments of inertia of all the mechanical components such as the rotor, the speed reducer 5, and the linear motion mechanism 6 (however, the influence of deceleration is taken into consideration as appropriate). On the other hand, when the transmission unit is in a separated state, for example, a backlash in the gear or the like, the moment of inertia of the electric actuator DA is the moment of inertia excluding the member separated by the transmission unit, and in the minimum case, the motor 4 It can only be a motor rotor. In other words, when the transmitting unit is in the separated state, the moment of inertia may be relatively reduced as compared with the case where the transmitting unit is in the contacting 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 decrease in the moment of inertia due to the separation of the transmission unit. .. At this time, the control stability may decrease contrary to the speeding up of the control, and problems such as a decrease in controllability and deterioration of NVH may occur due to the vibrational operation. Further, for example, when the arithmetic expression in the control arithmetic unit is constructed assuming that the transmission unit is in a separated state, the phase in the control characteristics is delayed due to the increase in the moment of inertia accompanying the contact of the transmission unit, and the control stability is controlled. May decrease. In addition, the responsiveness may be lower than expected, which may adversely affect the braking distance.

According to the configuration of the present embodiment, a part or the whole of the transmission unit is separated from the first control calculation unit 23a that performs a control calculation assuming that the transmission unit from the motor rotor to the speed reducer 5 is in a contact state. By appropriately switching between the second control calculation unit 23b, which performs the control calculation assuming a state, and the control switching unit 23c, the problem caused by the contact or separation of these transmission units can be solved.

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

In the mechanical coupling state estimation unit 24, for example, when the estimated load is zero or a low load state of less than a predetermined value, the transmission unit is separated based on the estimated load, and the estimated load is equal to or more than 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 pressurization applied to the transmission portion by the reaction force is zero or extremely small, so that the transmission portion tends to be separated. On the other hand, when a brake load is applied, the transmission portion is likely to be maintained in a contact state due to the pressurization due to the 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, even in a low load state where the brake load is not zero, the reaction force, that is, the pressurization may become zero due to the influence of the hysteresis of the mechanical system. It is preferable to presume that separation may occur.

The motor driver 18 controls the electric power supplied by the electric motor 4. The motor driver 18 constitutes, for example, a half-bridge circuit using a switch element such as a field effect transistor (abbreviated as FET), and PWM control in which the voltage applied to the motor is determined by the ON-OFF duty ratio of the switch element. If it is configured to perform the above, it will be inexpensive and have high performance. Alternatively, a transformer circuit or the like may be provided to perform PAM control. Further, as a switching potential source of the H arm switch element that connects 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 separately provided.

<Configuration example of mechanical coupling state estimation unit, etc.>
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 the contact state or the separated state based on the result of the estimated load, and the control calculation unit 23 is switched based on this determination. show.

When the actuator load is large, the transmission portion of the electric actuator is generally maintained in a contact state due to the reaction force against the load. On the other hand, when the load is small, the reaction force is not generated or is very small. 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, the determination of the intermediate state may be provided between the separation and the contact. That is, for example, in the case of a load, a first threshold value for determining separation and a second threshold value for determining contact are provided, and the separation and contact are continuous with the first threshold value and the second threshold value as an intermediate state. It may be a process of switching to. In the intermediate state, the control calculation unit 23 emphasizes the first control calculation unit 23a when the estimation result of the machine coupling state estimation unit 24 is close to the contact state, and the second control calculation unit 23 is emphasized when the estimation result is close to the separation state. It has a control switching unit 23c in which the control calculation unit 23b of the above is emphasized. As a result, it is possible to prevent the occurrence of chattering or the like at the time of control switching even when an error occurs between the state of the transmission unit in the actual actuator operation and the coupling state estimation result. Alternatively, in order to make the process simpler, binary switching may be performed based on the magnitude of a predetermined threshold value.

The control calculation unit 23 switches the first and second control calculation units 23a and 23b for performing control calculations from the target motor angle and the estimated motor angle, and the first and second control calculation units 23a and 23b. It is provided with a control switching unit 23c that is switched by 26. The first and second control calculation units 23a and 23b respectively follow and control a control amount which 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 be capable of not only switching between binary values but also generating an intermediate state thereof. Further, a third and subsequent control calculation units may be provided.

<About action and effect>
According to the electric actuator DA and the electric brake device 1 described above, when the contact state of the transmission unit is estimated by the mechanical coupling state estimation unit 24, the control calculation unit 23 makes the first control calculation unit 23a effective. Controls the electric motor 4. In this case, it is possible to exhibit high-speed and high-precision controllability in consideration of the moment of inertia of the entire electric actuator.
On the other hand, when the transmission unit is presumed to be in a separated state, the control calculation unit 23 effectively uses the second control calculation unit 23b in which the magnitude of the driving force of the electric motor 4 is calculated to be smaller than that of the first control calculation unit 23a. And. In this case, it is possible to perform a control calculation based only on the motor inertia, for example, in a state where the load is zero to low, which is easily affected by backlash or the like. Therefore, for example, it is possible to suppress motor vibration caused by equivalent inertia fluctuations between backlashes and improve NVH. Further, it is possible to suppress the electric motor 4 from swinging between the backlashes, and thereby it is also possible to suppress the power consumption.

<About other embodiments>
In the following description, the same reference numerals will be given to the parts corresponding to the matters described in advance in each embodiment, and duplicate description will be omitted. When only a part of the configuration is described, the other parts of the configuration are the same as those described above unless otherwise specified. It has the same action and effect from the same configuration. Not only the combinations of the parts specifically described in each embodiment, but also the combinations of the embodiments can be partially combined as long as the combination does not cause any trouble.

FIG. 4 shows an example in which the load estimator is not provided and the reaction force estimation unit 19A, which is a load estimation function unit, is provided in the motion state estimator 20 with respect to the configuration example of FIG. The reaction force estimation unit 19A may have a function of estimating including the reaction force in the state quantity estimated by the state estimation observer, for example, a disturbance observer based on the output difference between the controlled target model and the actual machine. May be 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 shown in FIG. 5, the machine coupling state estimation unit 24 determines, for example, the separation / contact state of the transmission unit by using the deviation between the target motor angle which is the target value and the estimated motor angle which is the control amount. You may. When the absolute value of the deviation between the target motor angle and the estimated motor angle is small, it is easy for the torque direction to reverse in order to make the estimated motor angle follow the target motor angle, that is, a backlash intermediate state 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 in order to make the estimated motor angle follow the target motor angle for the time being, so that the backlash intermediate state is unlikely to occur.

Therefore, the mechanical coupling state estimation unit 24 determines that the transmission unit is in a separated state when the absolute value of the deviation is smaller than the specified value, and transmits when the absolute value of the deviation is larger than the specified value. It can be determined that the portions are in contact with each other. When the motor angle deviation is relatively large, the electric motor continuously rotates in one direction so as to reduce the angle deviation, so that the transmission part can contact, and when the angle deviation is relatively small, the angle deviation is zero. Alternatively, there is a high possibility that the electric motor will change the rotation direction in order to converge within the permissible range, and the transmission unit is in a state of being easily separated. Therefore, the mechanical coupling state estimation unit 24 can estimate the separation / contact state of the transmission unit based on the angle deviation of the electric motor. In addition, instead of the deviation of the estimated motor angle and the target motor angle in this figure, the deviation between the estimated load and the target load can also be used. Further, when the load is sufficiently large, it can be determined that the transmission portion is in a contact state due to the reaction force of the load regardless of the magnitude of the deviation.

Therefore, the mechanical coupling state estimation unit 24 is provided with a coupling state estimation execution determination unit 27 that determines whether to estimate the separation / contact state based on the estimated load, and if the estimated load is larger than a predetermined value, it is determined that the contact state is present. can do.
According to this configuration, when the absolute value of the deviation is smaller than the predetermined value, it is estimated that the transmission unit is in the separated state, and the unit 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 contact surface of the transmission portion being separated during the backlash, the equivalent moment of inertia of the electric actuator being reduced, and the response being oscillating.
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 in combination, and for example, the separation / contact state derived by adding or multiplying the judgment results of each other. The judgment result may be used.

FIG. 6 shows an example in which a disturbance generated by an external force on an electric motor is estimated and a separation / contact state is determined based on the estimated disturbance. In this example, the control device has a disturbance estimation unit 28 that estimates a disturbance (estimated disturbance) applied to the electric motor, including a reaction force with respect to 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 in the contact state, the driving force of the electric motor is used as an estimated disturbance. When it is estimated that a disturbance of a magnitude or more determined in the same direction is applied, the mechanical coupling state estimation unit 24 has a function of transitioning the estimation result from the contact state to the separated state. The estimated disturbance may be derived by, for example, a disturbance estimation observer based on an operation amount, a control amount, an equation of motion of an electric actuator, or the like.

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

That is, since the backlash intermediate state is reached and the transmission portion is separated, it can be determined that the separation / contact state is separated when the load is small and the estimated disturbance is the assist force. In addition, in order to exclude the influence of the motor torque error and the like, the judgment based on the assist force may be made depending on the case where the estimated disturbance is larger than the predetermined assist force.
Further, as a condition for determining that the separation / contact state has changed from separation to contact, in addition to the load shown in FIG. 6, for example, the deviation shown in FIG. 5 may be used in combination. That is, when the absolute value of the deviation becomes a predetermined value or more, it may be determined that the separated / contact state is the contact state for the reason described together 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 hinders rotation acts. Under such circumstances, it is presumed that the 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 rushed into the backlash, so that it is possible to appropriately switch to the second control calculation unit 23b, and it is possible to prevent the response from becoming oscillating.

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, for example, by differentiating the estimated angle, or by a state estimation observer or the like.
When the load is small, it is considered that what is generated as the disturbance of the electric motor is the rotational resistance, the sliding resistance, or the resistance force due to the kinematic viscosity mainly due to the frictional force. In other words, it is considered that the disturbance force that reduces the motor torque is the main disturbance. At this time, when the absolute value of the motor angular acceleration becomes larger than the angular acceleration that can be generated with respect to the moment of inertia of the entire electric actuator, it is considered that this is due to the decrease in the moment of inertia of the electric actuator.

That is, since the transmission unit is separated in the backlash intermediate state, it can be determined that the separation / contact state is separated when the absolute value of the angular acceleration becomes larger than a predetermined value. The case where the absolute value of the angular acceleration becomes larger than a predetermined value is preferably the case where the magnitude of the angular acceleration that can be derived from a predetermined operating amount such as motor torque and the moment of inertia is exceeded, but the processing is simplified. Therefore, the maximum angular acceleration that can occur may be exceeded. Further, when the magnitude of the angular acceleration is exceeded, it is preferable to set a threshold value in consideration of the influence of the motor torque error.

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

FIG. 8 shows an example in which 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 has 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 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 in the contact state, the deviation changes from positive to negative or from negative to positive. When 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, when controlling an extremely small load, zero crossing of the estimated load with respect to the target load may be used.

When the contact state of the transmission part is separated and the moment of inertia drops mainly to the motor rotor only, the moment of inertia of the entire motorized actuator becomes excessive in the amount of operation by the assumed control calculation, and the specified command value is reached. The amount of operation is often chattering. At that time, since zero crossing with a relatively short cycle occurs, if the zero crossing cycle is shorter than a predetermined time, it can be determined that the separation / contact state is separation. If the zero crossing cycle is longer than a predetermined time, it can be determined that the contact state is reached. That is, when the transmission part is separated and the moment of inertia is reduced and the control stability is lowered, zero crossing occurs in a short cycle that cannot occur unless the moment of inertia is reduced, so that the transmission part is separated and contacted. The state can be estimated.

For any or more of the mechanical coupling state estimation units 24, the control switching unit 23 is the first and the first based on the threshold value for determining that 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 unit 23a and 23b can be switched. At this time, even if it is determined as the degree of separation or contact of the transmission unit at the intermediate value of the plurality of threshold values and the degree of influence of the first and second control calculation units 23a and 23b is determined based on these degrees. good. By performing such smooth switching, for example, deterioration of NVH caused by the switching operation itself can be prevented.

According to this configuration, when the equivalent inertia is reduced only to the motor rotor due to the influence of backlash etc. and the response becomes oscillating, the equivalent inertia becomes high frequency zero crossing compared to the case of the entire electric actuator. Occur. Therefore, since it can be determined that the backlash intermediate state of the power transmission mechanism has occurred by this configuration, it is possible to appropriately switch to the second control calculation unit 23b, and it is possible to prevent the response from becoming oscillating. In addition, in order to exclude erroneous detection due to the influence of noise or the like, for example, a process of detecting only zero crossing exceeding a predetermined amplitude may be performed, and zero crossing within a predetermined cycle range continuously occurs for a predetermined time or longer. You may make a judgment based on the above.
The methods of FIGS. 3 and 5 to 8 may be used in combination as long as they do not cause a contradiction.

FIG. 9 shows an example in which the electric steering device is configured as a rotary actuator main body AH instead of a linear 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 the rotational torque load is handled instead of the linear motion load. The torque sensor Sc may have a function of estimating torque from the twist of the steering rod or the like, for example.

Each block diagram only shows the concept of functional configuration, and elements not shown in the figure shall be provided as appropriate according to the requirements. Further, each functional block is provided for convenience, and can be appropriately integrated or divided according to the convenience of implementation.
Each embodiment may be configured to be used in combination as appropriate as long as the functional inconsistency does not occur. For example, in the example of FIG. 2, the reaction force estimation unit 19A shown in FIG. 4 may be provided and used for disturbance offset control or the like. Further, the connection form of each function is shown as an example, and can be changed within a range that does not interfere with the function.

In addition, it is also possible to build another application that basically follows the configuration of each figure. For example, in the electric brake device shown in FIGS. 2 and 4, it can be applied to an electric press device in which a press type or the like is connected to a linear motion mechanism, and in the electric steering device shown in FIG. 9, it can be used as a speed reducer. It can also be applied to an electric valve device or the like that connects a valve device or the like and controls the valve opening degree.

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 (reduction ratio ≈1) that does not decelerate may be used, or a speed-increasing machine may be used (reduction ratio <1).

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

Although the embodiments for carrying out the present invention have been described above based on the embodiments, the embodiments disclosed this time are exemplary in all respects and are not limiting. The scope of the present invention is shown by the scope of claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

2 ... Control device 4 ... Electric motor 5 ... Reducer 6 ... Linear mechanism 8 ... Brake rotor 9 ... Friction material 19 ... Load estimator (load estimation function unit)
20a ... Angle estimation unit 23 ... Control calculation unit 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 Equation actuator

Claims (7)

Controls the electric motor, a power transmission mechanism that transmits the driving force of the electric motor via a transmission unit having a play that causes a contact state and a separation state by switching the operation in the forward direction and the reverse direction, and the electric motor. In an electric actuator equipped with a control device
The control device is
An angle estimation unit that estimates the motor angle of the electric motor,
A load estimation function unit that estimates the load that the driving force of the electric motor acts on through the power transmission mechanism, and
A control calculation unit that uses the estimated value of the load or the motor angle as the operation amount and follows and controls the control amount that is the estimated value of the load or the motor angle with respect to a given target value.
When the estimated load value is smaller than the specified value, the transmission unit is in a separated state, and when the estimated load value is larger than the specified value, the transmission unit is estimated to be in the contact state. Equipped with 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 a separated state by the mechanical coupling state estimation unit. Electric actuator to have. In the electric actuator according to claim 1, the mechanical coupling state estimation unit 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 specified value, and estimates that the transmission unit is in a contact state when the absolute value of the deviation is larger than a specified value. In the electric actuator according to claim 1 or 2, the control device has 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 is in a situation where the stored estimation result is in a contact state. When it is estimated that a disturbance of a magnitude or more determined in the same direction as the driving force of the electric motor is applied as the disturbance estimated in the above, the mechanical coupling state estimation unit separates the estimation result from the contact state. An electric actuator that has the function of transitioning to a state. In 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 when the control amount is followed and controlled with respect to the target value, and a function of estimating the angular acceleration of the electric motor. And 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 the estimated result is estimated in a situation where the stored estimation result is in a contact state. When the magnitude of the angular acceleration is estimated to be larger than a predetermined value, the mechanical coupling state estimation unit is an electric actuator having a function of transitioning the estimation result from a contact state to a separated state. In the electric actuator according to claim 1 or 2.
The control device is a zero crossing detector that detects that the deviation between the target motor angle, which is the target value, and the estimated angle, which is the 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 in a contact state, the deviation is positive. The mechanically coupled state estimation unit is an electric actuator having a function of transitioning the estimation result from the contact state to the separated state when the transition from negative or negative to positive occurs a plurality of times within a predetermined time. In the electric actuator according to claim 1 or 2.
The mechanical coupling state estimation unit sets the first threshold value for presuming that the transmission unit is in the contact state and the transmission unit in the separation state under the condition of determining whether the transmission unit is in the separation state or the contact state. It comprises a second threshold that is presumed to be, and is 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 machine coupling state estimation unit is close to the contact state, and the estimation result is obtained. An electric actuator having a control switching unit in which the second control calculation unit is emphasized when the separated state is approached. The electric actuator according to any one of claims 1 to 6, the friction material operated by the electric actuator, and a brake rotor that generates a braking force by contact with the friction material are provided. Electric brake device.

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