JP2024034575A - Vehicle control device, vehicle control method, and vehicle control system - Google Patents

Abstract

The present invention provides a vehicle control device, a vehicle control method, and a vehicle control system that can effectively suppress pitching fluctuations when a vehicle is stopped. [Solution] When the vehicle is decelerated based on the total braking torque, the control command to be output to generate the driving force by the rear motor 7 in a state where frictional braking force is generated is determined based on the state of the vehicle. Correct according to the reliability of the calculation result. [Selection diagram] Figure 1

Description

The present invention relates to a vehicle control device, a vehicle control method, and a vehicle control system.

Patent Document 1 aims to suppress pitching fluctuations when a vehicle is about to stop, and acquires a physical quantity related to vehicle speed and a physical quantity related to the required braking force necessary to decelerate the vehicle, and based on the physical quantity related to the required braking force. A technique has been disclosed in which, when decelerating a vehicle, a drive device generates a driving force while a frictional braking force is being generated.

Japanese Patent Application Publication No. 2022-056583

However, in the conventional vehicle control device described above, the driving force is increased based on the command value of the frictional braking force, but there is a difference between the estimated frictional braking force and the braking force actually generated in the vehicle. Errors occur due to changes in the coefficient of friction due to changes in the temperature of the brake pads, etc., and due to the influence of these errors, there is a risk that smooth stopping may not be achieved effectively.
One of the objects of the present invention is to provide a vehicle control device, a vehicle control method, and a vehicle control system that can effectively suppress pitching fluctuations when the vehicle is stopped.

A vehicle control device in an embodiment of the present invention outputs an output to cause a drive device to generate a driving force while a frictional braking force is being generated when decelerating the vehicle based on a physical quantity related to the total braking force. The control command is corrected according to the reliability of the calculation result due to the state of the vehicle.

Therefore, according to the present invention, it is possible to effectively suppress pitching fluctuations when the vehicle is stopped.

1 is a schematic diagram of an electric vehicle 1 equipped with a vehicle control system according to a first embodiment. FIG. 3 is a control block diagram of the rear motor 7 of the first embodiment. FIG. 3 is a control block diagram of a total braking torque calculation unit 34 of the first embodiment. 3 is a control block diagram of a control gain calculation unit 35 of the first embodiment. FIG. 3 is a control block diagram of an additional torque calculation unit 37 in the first embodiment. FIG. FIG. 3 is a control block diagram of an estimated frictional braking force correction gain calculation unit 33 according to the first embodiment. FIG. 3 is a control block diagram of a reliability evaluation filter section 73 according to the first embodiment. It is a cutoff frequency map based on the magnitude of frictional braking force. It is a cutoff frequency map based on the rate of change of frictional braking force. Figure 3 is a cutoff frequency map based on vehicle speed. 8 is a control block diagram of a gain converting section of variable cutoff filter 85. FIG. 7 is a control block diagram of a reliability evaluation gain calculation unit 74 of the first embodiment. FIG. This is a reliability evaluation gain map based on the magnitude of frictional braking force. This is a reliability evaluation gain map based on the rate of change in frictional braking force. It is a reliability evaluation gain map based on pad temperature changes. 5 is a time chart of vehicle speed, G sensor value, brake fluid pressure, and pad μ, showing an example of the operation of the reliability evaluation filter unit 73 of the first embodiment. 5 is a time chart of vehicle speed, G sensor value, brake fluid pressure, pad μ, and motor torque, showing an operation example of the reliability evaluation gain calculation unit 74 of the first embodiment.

[Embodiment 1]
FIG. 1 is a schematic diagram of an electric vehicle 1 equipped with a vehicle control system according to a first embodiment.
The electric vehicle 1 has front wheels 2FL, 2FR, rear wheels 2RL, 2RR, and friction brakes (friction braking devices) 3FL, 3FR, 3RL, 3RR (hereinafter referred to as friction brakes) installed on each wheel that generate frictional braking force on the wheels. Friction brakes are also collectively referred to as friction brakes 3).
The electric vehicle 1 includes a rear motor (drive device) 7 that outputs torque to rear wheels 2RL and 2RR. quintessential quintupletsThe rear wheels 2RL and 2RR are also collectively referred to as drive wheels 2. Power transmission between rear motor 7 and rear wheels 2RL, 2RR is performed via reduction gear 8, differential 10, and rear axles 6RL, 6RR.

Each wheel 2FL, 2FR, 2RL, 2RR has a wheel speed sensor 11FR, 11FL, 11RL, 11RR that detects the wheel speed. The rear motor 7 has a rear wheel resolver 13 that detects the motor speed (motor rotation speed). The electric vehicle 1 also includes a G sensor 5 that detects acceleration in the longitudinal direction (hereinafter also simply referred to as acceleration) of the vehicle.
The friction brake 3 presses a brake pad against a brake rotor that rotates integrally with each wheel in the direction of the rotational axis of each wheel to generate braking force by frictional force. The friction brake 3 of Embodiment 1 will be described with a configuration in which the brake pad is pressed by a foil cylinder operated by brake fluid pressure, but it may also be configured in which the brake pad is pressed through a ball screw mechanism or the like driven by an electric motor. Not limited.

Electric vehicle 1 has a low voltage battery 14 and a high voltage battery 15. The low voltage battery 14 is, for example, a lead acid battery. High voltage battery 15 is, for example, a lithium ion battery or a nickel metal hydride battery. High voltage battery 15 is charged with power boosted by DC-DC converter 16.
The electric vehicle 1 includes a vehicle control device (control unit) 17, a brake control device 18, a rear motor control device 20, and a battery control device 19. Each control device 17, 18, 20 shares information with each other via CAN bus 21.

The vehicle control device 17 acquires information from various sensors such as a rear wheel resolver 13, an accelerator pedal sensor 22 that detects the accelerator operation amount, a brake sensor 23 that detects the brake operation amount, and a gear position sensor 24, and performs vehicle integration. Take control. The vehicle control device 17 outputs the driver's requested torque that the rear motor 7 should output according to the requested distributed torque in response to the requested torque corresponding to the driver's accelerator operation, brake operation, etc.
The brake control device 18 acquires information from various sensors such as the brake sensor 23, sets a target braking torque that is a torque conversion value of the vehicle's target braking force, and adjusts the brake fluid required for each wheel according to the target braking torque. It generates pressure and outputs it to the friction brake 3 through the hydraulic piping 18a.

The battery control device 19 monitors the charging/discharging state of the high voltage battery 15 and the single cells that make up the high voltage battery 15. The battery control device 19 calculates a battery required torque limit value based on the charging/discharging state of the high voltage battery 15 and the like. The battery required torque limit value is the maximum torque allowed in the rear motor 7. For example, when the amount of charge of the high voltage battery 15 is decreasing, the battery required torque limit value is set to a smaller value than usual.
The rear motor control device 20 controls the electric power supplied to the rear motor 7 based on the rear required torque.

In the electric vehicle 1 of the first embodiment, the braking torque actually generated in the vehicle is estimated when the vehicle is stopped, with the aim of suppressing unpleasant shaking of the vehicle and reducing fatigue of the occupants when the vehicle is stopped. Anti-jerk control is performed in which the rear motor 7 outputs a driving torque equivalent to the total braking torque. As a result, the longitudinal jerk (jerk) that occurs when the vehicle stops with a certain amount of brake operation can be reduced by approximately 68% compared to the case without anti-jerk control. In other words, you can achieve a smooth stop without having to use the brakes skillfully.

FIG. 2 is a control block diagram of the rear motor 7 of the first embodiment.
The driver requested torque calculation unit 31 calculates the driver requested torque from the accelerator operation amount and vehicle speed. The wheel speed is determined by any suitable method from each wheel speed detected by each wheel speed sensor 11FR, 11FL, 11RL, 11RR, but at low speeds, it is determined by referring to the motor speed detected by the rear wheel resolver 13.
The slope resistance calculation unit 32 calculates slope resistance, which is the resistance that acts on the vehicle due to the road surface slope, based on the vehicle speed, the G sensor value, and the vehicle weight. Specifically, the estimated gradient acceleration caused by the gradient is determined from the deviation between the differential value of the vehicle speed and the G sensor value, and the gradient resistance is calculated from the estimated gradient acceleration caused by the gradient and the vehicle weight.

The estimated frictional braking force correction gain calculation unit 33 calculates the estimated frictional braking force due to changes in pad μ (friction coefficient) based on the G sensor value, vehicle speed, estimated frictional braking force, running resistance, vehicle weight, motor torque, and brake pad temperature. Calculate the final correction gain for correcting the power estimation error. When the pad μ changes due to changes in temperature, humidity, etc., a deviation occurs in the estimated frictional braking force compared to the braking force actually generated on the vehicle by the brake. Therefore, the pad μ is estimated, and a gain for correcting the estimated frictional braking force (torque equivalent value thereof) is calculated in order to cancel the error of the estimated pad μ with respect to the nominal value of the pad μ.
The estimated frictional braking force is obtained as the sum of the estimated frictional braking forces of each wheel. The estimated frictional braking force Bi for each wheel is calculated using the following equation (1).
Estimated frictional braking force Bi for each wheel = brake fluid pressure x cylinder area x brake effective radius x pad μ (nominal value)...(1)
Here, once the nominal value of the pad μ is set, it is not changed while the vehicle is running. The nominal value is set by obtaining a map of the temperature-μ characteristic of the brake pad in advance and referring to the map. The temperature of the brake pad when calculating the nominal value may be the outside temperature at the start of driving, or may be a predefined temperature (for example, 20° C.).
The running resistance may be calculated or estimated based on a change in running resistance obtained in advance with respect to a change in vehicle weight or vehicle speed.
The estimated friction braking force may be estimated not from the brake fluid pressure but from the stroke amount of the driver's brake pedal.
Details of the estimated frictional braking force correction gain calculation unit 33 will be described later.

The total braking torque calculation unit 34 calculates the total braking torque based on the running resistance, estimated frictional braking force, slope resistance, and final correction gain. FIG. 3 is a control block diagram of the total braking torque calculation unit 34 of the first embodiment. The braking force torque conversion unit 41 converts the estimated frictional braking force into an estimated frictional braking torque. Multiplier 42 multiplies the estimated frictional braking torque by the final correction gain to calculate a corrected estimated frictional braking torque that corrects the estimation error due to the change in μ of the brake pad. The first adder 43 and the second adder 44 add the torque equivalent to the slope resistance and the torque equivalent to the traveling resistance to the corrected estimated friction braking torque. The limiter 45 compares the value obtained by adding the torque equivalent to gradient resistance and the torque equivalent to running resistance to the corrected estimated frictional braking torque with 0, and outputs the larger value as the total braking torque.

The control gain calculation unit 35 calculates a control gain based on the vehicle speed and the total braking torque. FIG. 4 is a control block diagram of the control gain calculation unit 35 of the first embodiment. The estimated acceleration value calculation unit 51 calculates acceleration by differentiating the vehicle speed. The acceleration-based control gain map 52 sets acceleration-based control gains according to acceleration. In the acceleration-based control gain map 52, if the deceleration is smaller than the default value x2 (G) as an absolute value, the acceleration-based control gain is set to 1 (100%), while the absolute value is set to the default value x2 (G). When the above deceleration occurs, the acceleration-based control gain is gradually decreased as the absolute value of the deceleration increases. The minimum value of the acceleration-based control gain is 0 (0%). This makes it possible to avoid adding torque during sudden braking. It goes without saying that during sudden braking, it is more desirable to secure braking force than to suppress vibrations in the pitching direction.

The speed-based control gain map 53 sets speed-based control gains based on a three-dimensional map according to vehicle speed and total braking torque. The speed-based control gain has a characteristic that it linearly decreases as the total braking torque decreases only in a predetermined region where the total braking torque is around 0, and reaches a maximum value of 1 in most regions exceeding the predetermined region. Note that the maximum value may be a positive value other than 1. Further, the speed-based control gain is set to increase linearly as the vehicle speed decreases. Furthermore, the speed-based control gain is set so that the vehicle speed (gain increase start speed) at which the value rises from 0 increases as the total braking torque increases. That is, the speed-based control gain has a characteristic that as the total braking torque increases, the vehicle speed at which the anti-jerk control command is applied (vehicle speed at which the generation of driving force by anti-jerk control starts) increases.

The stop judgment unit 54 inputs the vehicle speed, total braking torque, vehicle weight, and estimated frictional braking force, and clears the stop judgment flag (=0) if the stop time is other than 0, and the stop time becomes 0. In this case, the stop judgment flag is set (=1).
The control gain rate limiter 55 limits the rate of change of the speed-based control gain on the increasing and decreasing sides. Furthermore, when the stop determination flag is set (=1), the decreasing speed limit value that has been used until then is changed.
Multiplier 56 outputs a value obtained by multiplying the acceleration-based control gain by the speed-based control gain as the final control gain.

Returning to FIG. 2, the multiplier 36 multiplies the total braking torque by the control gain to calculate the total braking torque after multiplication by the control gain.
The additional torque calculation unit 37 calculates additional torque as the anti-jerk control torque based on the driver requested torque and the total braking torque after multiplication by the control gain. FIG. 5 is a control block diagram of the additional torque calculation unit 37 of the first embodiment. The limiter 61 compares the driver's requested torque with 0 and outputs the larger value. Comparator 62 subtracts the output of limiter 61 from the total braking torque after multiplication by the control gain. The limiter 63 compares the output of the comparator 62 with 0, and outputs the larger value as the additional torque.
The adder 38 adds the added torque to the driver's requested torque and sets the added torque as the rear requested torque.

FIG. 6 is a control block diagram of the estimated frictional braking force correction gain calculation unit 33 of the first embodiment.
The correction gain reference value calculation unit 71 calculates a correction gain reference value based on the estimated frictional braking force, motor torque, G sensor value, running resistance, and vehicle weight with reference to equation (2) below.
Correction gain reference value = (G sensor value x vehicle weight - braking/driving force equivalent to motor torque - running resistance)/estimated frictional braking force...(2)
As the motor torque, the final torque command value of the vehicle control device or the final torque command value of the inverter may be used.

Note that a differential value of vehicle speed may be used instead of the G sensor value. In that case, since the differential value of the vehicle speed also includes the influence of gradient resistance, the numerator on the right side of equation (2) is changed as follows.
(Derivative value of vehicle speed x vehicle weight - braking/driving force equivalent to motor torque - running resistance - gradient resistance)
Furthermore, since the pitch angle of the vehicle affects the longitudinal acceleration sensor value, the pitch angle of the vehicle may be detected or estimated and taken into account when calculating the correction gain reference value or when calculating the gradient resistance.
The estimated frictional braking force change rate calculating unit 72 calculates the rate of change of the estimated frictional braking force by differentiating the estimated frictional braking force.

The reliability evaluation filter section 73 evaluates the reliability of the correction gain reference value based on the vehicle speed, the estimated frictional braking force, and the estimated frictional braking force change rate (calculates the reliability), and sets the correction gain reference value according to the evaluation result. Correct the value. The reliability is the degree of reliability of the correction gain reference value (variance of estimation accuracy, expectation of estimation accuracy). FIG. 7 is a control block diagram of the reliability evaluation filter section 73 of the first embodiment. The reliability evaluation filter unit 73 places emphasis on the current correction gain reference value in the reliable section of the correction gain reference value, and places more emphasis on the current correction gain reference value instead of the current correction gain reference value in the less reliable section of the correction gain reference value. In order to estimate the output value (correction gain) of the performance evaluation filter with emphasis, for example, a variable cutoff filter 85 with variable response as shown in FIG. 11 is used. Here, for the responsiveness of the variable cutoff filter 85, the smallest one among the output values of the respective frequency maps 81 to 83 in the previous stage is used. FIG. 11 is a control block diagram of the gain conversion section of the variable cutoff filter 85. Gain conversion section 851 converts the cutoff frequency determined by each frequency map 81 to 83 into a gain corresponding to the cutoff frequency. The first multiplier 852 multiplies the correction gain reference value by a gain. Comparator 853 subtracts the gain from one. The second multiplier 854 multiplies the output of the comparator 853 by the previous output value (correction gain) of the variable cutoff filter 85. The previous value holding unit 855 holds the previous output value of the variable cutoff filter 85. Adder 856 outputs a correction gain obtained by multiplying the output value of first multiplier 852 and the output value of second multiplier 854. Here, the characteristics of the variable cutoff filter 85 are similar to those of an LPF (Low Pass Filter), and furthermore, when the cutoff frequency is set to 0, the output value of the gain conversion section is set to 0, Since the filter configuration can be such that the output value of the previous variable cutoff filter 85 is held, the response to the correction gain reference value estimated in the current control cycle can be changed appropriately depending on the reliability. , the correction gain can be calculated.

The cutoff frequency map 81 based on the magnitude of the frictional braking force is a map for estimating the value by placing emphasis on the estimated value in the section where the influence of disturbances etc. that have not been fully taken into account in the formula is likely to be small. be. The smaller the frictional braking force is, the greater the influence of the acceleration caused by the disturbance that cannot be taken into account in the formula becomes relatively greater than the acceleration generated by the frictional braking force included in the G sensor value. As a result, there is a possibility that the error between the true value to be actually corrected and the correction gain reference value estimated by equation (2) becomes large. Therefore, the cutoff frequency map 81 based on the magnitude of the frictional braking force increases the first cutoff frequency Y as the estimated frictional braking force increases. As shown in Figure 8, the first cutoff frequency Y takes the minimum value Y1 when the estimated frictional braking force is less than X1, and the maximum value Y2 when the estimated frictional braking force exceeds X2. In the case of X1 or more and X2 or less, the estimated frictional braking force is set to increase as the estimated frictional braking force increases. Further, as described above, when the estimated friction braking force is small, there is a possibility that the estimation error of the correction gain reference value increases due to the influence of disturbances that are not fully taken into account in the mathematical formula. Therefore, the cutoff frequency is lowered when the estimated frictional braking force is less than the prescribed estimated frictional braking force. Here, Y1 is set to a value other than 0, but it may be set to 0.

The cutoff frequency map 82 based on the rate of change of the frictional braking force is a map for estimating values with emphasis placed on values estimated in sections where the influence of response delay of the G sensor 5 is likely to be small. Since the G sensor 5 is mounted on the spring of the vehicle, even if frictional braking force actually occurs, there is a time lag before the G sensor value is detected. As a result, when the rate of change of the frictional braking force is fast, even though the denominator term in equation (2) increases due to the increase in the frictional braking force, the increase in the G sensor value part of the numerator is slow, so the correction gain reference value Estimation error increases. Therefore, when it is assumed that there is such a response delay, estimation is performed with emphasis placed on the previous output value of the variable cutoff filter. Note that even when pseudo-differentiation is used to differentiate the vehicle speed or when sensor noise is removed, there is a delay element such as a filter, so there is a response delay to an increase in frictional braking force. As mentioned above, the greater the rate of change in frictional braking force, the greater the response delay of the sensor, which is likely to increase the error from the true value. Therefore, the cutoff frequency map 82 based on the rate of change in frictional braking force is The second cutoff frequency W is made higher as the frictional braking force change rate is smaller.

As shown in FIG. 9, the second cutoff frequency W is the minimum value W1 when the absolute value of the estimated frictional braking force change rate exceeds |Z2|, and the second cutoff frequency W is the minimum value W1 when the absolute value of the estimated frictional braking force change rate is less than |Z1| In the case of , the maximum value W2 is taken, and if the absolute value of the estimated frictional braking force change rate is |Z1| or more and |Z2| or less, it is set so that it becomes smaller as the absolute value of the estimated frictional braking force change rate increases. ing. When the estimated frictional braking force changes at a fast rate, there is a risk that the output value of the G sensor 5 attached to the vehicle's springs will have a response delay due to the influence of the suspension's spring-mass damper system. . Therefore, when the estimated frictional braking force changes quickly, the cutoff frequency is set to be low in order to increase the weight of the previous output value of the variable cutoff filter. Here, although W1 is set to a value other than 0, it may be 0, and furthermore, although the characteristic is symmetrical with respect to 0, it may be an asymmetrical characteristic.

The cutoff frequency map 83 based on the vehicle speed is estimated with emphasis on the previous output value of the variable cutoff filter when the vehicle speed decreases. This is because brakes convert kinetic energy into thermal energy, so when the vehicle speed decreases, it is assumed that the state of the brake pads will not change easily even if a braking force is applied. The cutoff frequency map 83 based on vehicle speed increases the third cutoff frequency R as the vehicle speed increases. As shown in FIG. 10, the third cutoff frequency R takes the minimum value R1 when the vehicle speed is less than V1, the maximum value R2 when the vehicle speed exceeds V2, and the third cutoff frequency R takes the minimum value R1 when the vehicle speed is less than V1, and takes the maximum value R2 when the vehicle speed In this case, the speed is set to increase as the vehicle speed increases. When the vehicle speed is low, the state of the brake pads is difficult to change, and as the vehicle speed decreases, anti-jerk control intervenes, and when the motor torque increases, the motor torque decreases in the same way as when the rate of change of frictional braking force is fast. There is a risk that the response of the G sensor value will be delayed with respect to changes in the G sensor value, and the estimation error of the correction gain reference value will increase. Therefore, as the speed decreases, the cutoff frequency is lowered so that estimation can be performed with emphasis on the previous output value of the variable cutoff filter. Here, V1 may be, for example, the earliest vehicle speed at which the anti-jerk control starts intervening, which is defined by the gain characteristics of the anti-jerk control determined according to the total braking force and the speed, or it may be any other speed. Also, R1 may be 0.
The limiter 84 outputs the smallest value among the first cutoff frequency Y, the second cutoff frequency W, or the third cutoff frequency R as a cutoff frequency.
The variable cutoff filter 85 performs filter processing on the correction gain reference value according to the cutoff frequency output from the limiter 84.

Returning to FIG. 6, the reliability evaluation gain calculation unit 74 calculates a reliability evaluation gain for correcting the output value of the reliability evaluation filter unit 73 based on the estimated frictional braking force, the estimated frictional braking force change rate, and the brake pad temperature. Calculate. The reliability evaluation gain is a gain for reducing the final correction result when the output of the reliability evaluation filter section 73 is not very reliable or when it is not necessary to strongly intervene in anti-jerk control. . Note that during low-speed driving (for example, 1 km/h or less), a configuration may be adopted in which the reliability evaluation gain calculated up to that point is held. FIG. 12 is a control block diagram of the reliability evaluation gain calculation unit 74 of the first embodiment.

The reliability evaluation gain map 91 based on the magnitude of the frictional braking force increases the first reliability evaluation gain M as the estimated frictional braking force increases. As shown in FIG. 13, the first reliability evaluation gain M takes the minimum value M3 when the estimated frictional braking force is less than X1, and the maximum value 1 when the estimated frictional braking force exceeds X2. When is greater than or equal to X1 and less than or equal to X2, it is set such that the larger the estimated frictional braking force is, the higher it becomes. If the estimated frictional braking force is small, there is a high possibility that the creep torque and the braking force generated in the vehicle are close, and the amount of pitching of the vehicle is small, so the ride quality will be significantly affected even without anti-jerk control intervention. It is assumed that there will be no impact. However, since there is a high possibility that the estimation error of the correction gain will increase due to the influence of disturbance, etc., the gain is reduced in order to prevent the braking distance from erroneously increasing significantly.

The reliability evaluation gain map 92 based on the rate of change in frictional braking force increases the second reliability evaluation gain N as the rate of change in frictional braking force decreases. As shown in FIG. 14, the second reliability evaluation gain N takes the minimum value N3 when the estimated frictional braking force change rate exceeds Z2, and takes the maximum value 1 when the estimated frictional braking force change rate is less than Z1, When the estimated frictional braking force change rate is Z1 or more and Z2 or less, it is set so that the smaller the estimated frictional braking force change rate is, the higher it becomes. If the friction braking force changes quickly, there is a risk that the reliability evaluation filter unit 73 will stop updating to prevent the estimation from deteriorating, so if the friction braking force is increased, the difference between the previous estimation value and the Errors may occur. Therefore, when the estimated frictional braking force increases at a speed higher than the specified speed, the second reliability evaluation gain N is lowered because there is a possibility that the estimated frictional braking force increases significantly from the previous estimation result. Regarding depressing back, it can be assumed that an increase in brake pad temperature etc. will not occur, and it is thought that there will be no significant change from the previous estimation result (output value of the previous reliability evaluation filter), so in this example Although the second reliability evaluation gain is set to 1, the map may have a characteristic of reducing the second reliability evaluation gain when the estimated frictional braking force change rate due to stepping back is fast. In addition, in this embodiment, the gain is determined by referring only to the estimated frictional braking force change rate, but the gain is determined by referring to the frictional braking force change rate and the vehicle speed. A three-dimensional map may be used in which the gain decreases when the speed is high.

The reliability evaluation gain map 93 based on pad temperature change increases the third reliability evaluation gain Q as the pad temperature change amount is smaller with respect to the brake pad temperature during the previous friction braking. As shown in Figure 15, the third reliability evaluation gain Q takes the minimum value Q1 when the pad temperature change exceeds P2, takes the maximum value 1 when the pad temperature change is less than P1, and takes the maximum value 1 when the pad temperature change exceeds P1. , P2 or less, the setting is such that the smaller the pad temperature change, the higher the value. When the pad temperature change is small, the gain is increased because the reliability of the correction gain estimated during the previous braking is high, and when the pad temperature change is large, the gain is decreased because the reliability of the previous value is low. The pad temperature may be acquired by a sensor, or an estimated value may be used for the pad temperature. Furthermore, the final pad temperature during the previous friction braking may be used as the brake pad temperature during the previous friction braking.
The limiter 94 outputs the larger value of the second reliability evaluation gain N and the third reliability evaluation gain Q.
The multiplier 95 outputs a value obtained by multiplying the first reliability evaluation gain M by the output value of the limiter 94 as a reliability evaluation gain.
Returning to FIG. 6, the multiplier 75 outputs a value obtained by multiplying the output value of the reliability evaluation filter unit 73 by the reliability evaluation gain as a final correction gain.

Next, the effects of the first embodiment will be explained.
FIG. 16 is a time chart of the vehicle speed, G sensor value, brake fluid pressure, and pad μ, showing an example of the operation of the reliability evaluation filter unit 73 of the first embodiment.
In the interval from time t1 to t2, the rate of change in fluid pressure is fast, and the error in the estimated pad μ may increase due to the effects of delays in the G sensor value, etc. Therefore, the previous correction gain reference value is Increase and update the weight of the output value of the variable cutoff filter. In the case of FIG. 16, the cutoff frequency is set to 0 and the previous value is held.
In the section from time t3 to t4, the brake fluid pressure is low and the frictional braking force is weak, so the effects of external disturbances and sensor errors that have not been taken into account are relative to the effects of the frictional braking force included in vehicle deceleration. There is a risk that the estimation error will increase as the value increases. Therefore, in this case as well, the weight of the output value of the previous variable cutoff filter is increased and updated.

FIG. 17 is a time chart of vehicle speed, G sensor value, brake fluid pressure, pad μ, and motor torque, showing an example of the operation of the reliability evaluation gain calculation unit 74 of the first embodiment.
In the period from time t1 to t2, the rate of change in hydraulic pressure is fast and there is a risk that the reliability evaluation filter section 73 will stop updating, so the estimated frictional braking force after correction is reduced.
In the section from time t3 to time t4, the frictional braking force is small, so the ride comfort is unlikely to deteriorate even without strong anti-jerk control intervention. Therefore, considering the possibility that the estimated pad μ includes an error, the estimated frictional braking force after correction is reduced.

As described above, when decelerating the vehicle based on the total braking torque, the vehicle control device 17 of the first embodiment outputs an output to cause the rear motor 7 to generate a driving force in a state where a frictional braking force is generated. The control command (the final correction gain when calculating the total braking torque for determining the additional torque) is corrected according to the reliability of the calculation result due to the state of the vehicle. As a result, in the anti-jerk control, it is possible to output an additional torque that suppresses the influence of an estimation error of the frictional braking force on the actual braking force, and it is possible to effectively suppress pitching fluctuations when the vehicle is stopped.

The vehicle control device 17 corrects the control command according to the reliability of the calculation result caused by the state of the vehicle, including at least the vehicle speed, physical quantities related to the frictional braking force, and the temperature of the friction brake 3. In anti-jerk control, the error between the true value to be corrected and the corrected gain reference value varies greatly depending on the vehicle speed, friction braking force, and temperature of the friction brake 3, so it is controlled according to reliability taking these into account. By correcting the command, it is possible to more effectively suppress the influence of the estimation error of the frictional braking force in anti-jerk control.

The vehicle control device 17 includes a reliability evaluation filter unit 73 that corrects a predetermined correction gain reference value according to the reliability of the calculation result caused by the vehicle speed and the reliability of the calculation result caused by the physical quantity related to the frictional braking force. A reliability evaluation gain is set in accordance with the reliability of the calculation result caused by the physical quantity related to the friction braking force in the output value of , and a reliability evaluation gain is set according to the reliability of the calculation result caused by the physical quantity related to the temperature of the friction brake 3. A final correction gain is obtained by multiplying the reliability evaluation gain calculated by the reliability evaluation gain calculation unit 74 based on the reliability evaluation gain, and the control command is corrected based on the final correction gain. This makes it possible to estimate the current correction gain reference value in highly reliable intervals, and to place more emphasis on the previous output value of the variable cutoff filter in less reliable intervals, thereby reducing the influence of estimation errors. It can be suppressed more effectively. Furthermore, if the reliability of the output of the reliability evaluation filter section 73 is low, or if there is no need to strongly intervene in anti-jerk control, reducing the final correction gain may erroneously increase the braking distance significantly. can be suppressed.

The vehicle control device 17 sets the predetermined correction gain reference value based on the third cutoff frequency R based on the vehicle speed and the cutoff frequency set according to the reliability of the calculation result caused by the physical quantity related to the frictional braking force. The final correction gain is obtained by multiplying the output value passed through the variable cutoff filter 85 by the evaluation gain. By using the variable cutoff filter 85 and increasing the cutoff frequency in highly reliable sections and lowering the cutoff frequency in unreliable sections, the current correction gain reference value is given more weight in highly reliable sections. , it becomes possible to perform estimation that places more emphasis on the previous output value of the variable cutoff filter in an interval with low reliability.

The cutoff frequency, which is set according to the reliability of the calculation result caused by the physical quantity related to the frictional braking force, is the first cutoff frequency Y, which is set according to the reliability of the calculation result caused by the magnitude of the frictional braking force. and a second cutoff frequency W that is set according to the reliability of the calculation result caused by the rate of change of the frictional braking force. The smaller the frictional braking force is, the greater the possibility that the error from the true value will be, and when the rate of change of the frictional braking force is fast, the response delay of the G sensor 5 will increase the error. Therefore, by setting the cutoff frequency according to the magnitude of the frictional braking force and the rate of change of the frictional braking force, it is possible to suppress an increase in the estimation error of the frictional braking force.

The third cutoff frequency R based on the vehicle speed increases as the speed increases, and the first cutoff frequency Y based on the magnitude of the frictional braking force increases as the frictional braking force increases, and the third cutoff frequency R based on the frictional braking force change rate increases. 2. The cutoff frequency W is set higher as the rate of change is smaller. As a result, during a period in which reliability decreases, the estimation places more emphasis on the previous output value of the variable cutoff filter, so that an increase in the estimation error of the frictional braking force can be suppressed.

The cutoff frequency of the variable cutoff filter 85 is set by a select low of a cutoff frequency based on the vehicle speed, a cutoff frequency based on the frictional braking force, and a cutoff frequency based on the rate of change of the frictional braking force. By selecting the cutoff frequency using the select low, it is possible to suppress an increase in estimation error due to the estimation being performed with emphasis on the current correction gain reference value even though it is an interval with low reliability.

The physical quantity related to the temperature of the friction brake 3 is the temperature of the brake pad. Pad μ depends on pad temperature, and it is expected that the error will be small if the change in pad temperature is small from the previous friction braking or if the output value of the reliability evaluation filter estimated in the past is strongly used. If the pad temperature change is large, it is assumed that the error between the true value and the previously estimated output value of the reliability evaluation filter is large. Therefore, by changing the reliability gain in accordance with changes in pad temperature, it is possible to suppress an increase in braking distance due to an error between the estimated correction gain and the true value.

The reliability evaluation gain, which is set according to the reliability of the calculation result caused by the physical quantity related to the frictional braking force, is a first reliability evaluation gain M based on the magnitude of the frictional braking force, and a first reliability evaluation gain M based on the rate of change of the frictional braking force. 2 reliability evaluation gain N. If the frictional braking force is small, the riding comfort will not be greatly affected even if anti-jerk control does not intervene, and there is a high possibility that the estimation error will become large due to the influence of external disturbances. Further, when the rate of change in frictional braking force is large, there is a risk that the error between the estimated correction gain and the true value will become large by stopping the update in the reliability evaluation filter unit 73. Therefore, by setting the reliability evaluation gain according to the magnitude of the frictional braking force and the rate of change of the frictional braking force, it is possible to suppress an increase in the braking distance due to an error between the estimated correction gain and the true value.

The first reliability evaluation gain M, which is based on the magnitude of the frictional braking force, is higher as the frictional braking force is larger, and the second reliability evaluation gain N, which is based on the rate of change in the frictional braking force, is higher as the rate of change in the frictional braking force is smaller. The third reliability evaluation gain Q based on the pad temperature change is set to be higher as the pad temperature change is smaller since the previous friction braking. As a result, the reliability evaluation gain becomes smaller during a period in which reliability decreases, so it is possible to suppress an increase in the braking distance due to an error between the estimated correction gain and the true value.

The reliability evaluation gain is a first reliability evaluation gain M based on the magnitude of the frictional braking force, a second reliability evaluation gain N based on the frictional braking force change rate, and a third reliability evaluation gain Q based on the pad temperature change. It is set by multiplying the gain obtained by selecting high. For example, when the brake is pressed from a low speed, the increase in pad temperature etc. is small, so it is assumed that the coefficient of friction of the brake does not change significantly, but since the rate of change in frictional braking force is large, the second reliability evaluation The gain N becomes the minimum value. Therefore, by setting the second reliability evaluation gain N and the third reliability evaluation gain Q to select high, the third reliability evaluation gain Q is selected when the brake is stepped on from a low speed. It is possible to prevent the reliability evaluation gain from becoming too small even though the reliability of the output value of the evaluation filter is high.

[Other embodiments]
Although the embodiments for carrying out the present invention have been described above, the specific configuration of the present invention is not limited to the configuration of the embodiments, and design changes may be made within the scope of the gist of the invention. are also included in the present invention.
In the embodiment, an example is shown in which the present invention is applied to a rear-wheel drive electric vehicle, but it may also be applied to a front-wheel drive electric vehicle or a four-wheel drive electric vehicle. Further, the vehicle is not limited to an electric vehicle, and may be a vehicle equipped with an internal combustion engine, or a hybrid vehicle that can run using both an engine and a motor. In other words, when the vehicle is stopped using a friction brake, the structure is such that torque can be applied from the drive source side within the range where the vehicle can be stopped, or within the range where braking force is applied between the drive wheels and the road surface, or when the friction brake is used. Any configuration that can reduce this may be used.

In the reliability evaluation filter unit 73 of the first embodiment, the cutoff frequency is set by the select low of the output value of each frequency map 81 to 83, but the cutoff frequency is set by multiplying the output value of each frequency map 81 to 83. The off frequency may also be calculated.
Furthermore, since a response delay in the G sensor value may occur depending on the rate of change of the motor torque, for example, a frequency map may be added that changes the cutoff frequency with reference to the rate of change of the motor torque. Furthermore, if the road surface is considered to be rough, noise may increase in the G sensor value and the estimation accuracy of the correction gain reference value may deteriorate, so a frequency map has been added to change the cutoff frequency according to the road surface disturbance. (To estimate the road surface disturbance, noise occurring in the G sensor value may be detected using a high-pass filter or the like, or may be detected from information such as a stereo camera.)

In the reliability evaluation gain calculation unit 74 of the first embodiment, it is preferable that the upper limit of the three reliability evaluation gains M, N, and Q is set to 1, but it may be set to a value other than 1, and the lower limit value (M3, N3 , Q1) may also be set to 0. In addition, in the first embodiment, each reliability evaluation gain map 91 to 93 is used, but since it is assumed that the humidity on the pad surface also affects the braking force, the elapsed time since the last braking and the start of braking A map that calculates gains based on speed and humidity may be used.
In addition, in the example, cutoff frequency MAP81 based on the magnitude of frictional braking force, X1 and X2 of reliability evaluation gain MAP91 based on the magnitude of frictional braking force, cutoff frequency MAP82 based on the rate of change of frictional braking force, and frictional braking Although Z1 and Z2 of the reliability evaluation gain MAP92 based on the power change rate are expressed as the same variable, different values may be used for each.

1...Electric vehicle (vehicle), 3...Friction brake (friction braking device), 7...Rear motor (drive device), 17...Vehicle control device (control unit)

Claims (14)

A vehicle comprising: a friction braking device that generates a friction braking force on the vehicle; and a drive device that generates a driving force on the vehicle. A control device,
The control section includes:
obtaining a physical quantity related to a total braking force for decelerating the vehicle;
When decelerating the vehicle based on the physical quantity related to the total braking force, a control command is output to cause the drive device to generate a driving force while the frictional braking force is being generated,
correcting according to the reliability of the calculation result due to the state of the vehicle;
Vehicle control device The vehicle control device according to claim 1,
The control section includes:
The control command is corrected according to the reliability of the calculation result caused by the state of the vehicle, including at least a physical quantity related to the speed of the vehicle, a physical quantity related to the target frictional braking force of the vehicle, and a physical quantity related to the temperature of the friction braking device. do,
Vehicle control device. The vehicle control device according to claim 2,
The control section includes:
a predetermined correction gain reference value to an output value that is corrected according to the reliability of the calculation result due to the physical quantity related to the speed of the vehicle and the reliability of the calculation result due to the physical quantity related to the target frictional braking force;
Based on a gain set according to the reliability of the calculation result caused by the physical quantity related to the target friction braking force and a gain set according to the reliability of the calculation result caused by the physical quantity related to the temperature of the friction braking device. Multiply the obtained evaluation gain to find the final correction gain,
correcting the control command based on the final correction gain;
Vehicle control device. The vehicle control device according to claim 3,
The control section includes:
The predetermined correction gain reference value is set according to a cutoff frequency that is set according to the reliability of the calculation result caused by the physical quantity related to the speed of the vehicle and the reliability of the calculation result caused by the physical quantity related to the target frictional braking force. The output value is passed through a variable cutoff filter based on the cutoff frequency set by
Multiplying the evaluation gain to obtain a final correction gain;
Vehicle control device. The vehicle control device according to claim 4,
The cutoff frequency is set according to the reliability of the calculation result caused by the physical quantity related to the target frictional braking force, and the cutoff frequency is set according to the reliability of the calculation result caused by the magnitude of the target frictional braking force. frequency, and a cutoff frequency that is set according to the reliability of the calculation result due to the rate of change of the target frictional braking force.
Vehicle control device. The vehicle control device according to claim 5,
The cutoff frequency, which is set according to the reliability of the calculation result due to the physical quantity related to the speed of the vehicle, is higher as the speed is higher;
The cutoff frequency, which is set according to the reliability of the calculation result due to the magnitude of the target frictional braking force, is higher as the target frictional braking force is larger;
The cutoff frequency, which is set according to the reliability of the calculation result due to the rate of change of the target frictional braking force, is higher as the rate of change is smaller;
Vehicle control device to be set. The vehicle control device according to claim 6,
The cutoff frequency of the variable cutoff filter is
A cut-off frequency that is set according to the reliability of the calculation result resulting from the physical quantity related to the speed of the vehicle, a cut-off frequency that is set according to the reliability of the calculation result resulting from the magnitude of the target frictional braking force, and set by a select low of a cut-off frequency that is set according to the reliability of the calculation result caused by the rate of change of the target frictional braking force;
Vehicle control device. The vehicle control device according to claim 3,
The physical quantity related to the temperature of the friction braking device is the temperature of the brake pad,
Vehicle control device. The vehicle control device according to claim 8,
The gain set according to the reliability of the calculation result resulting from the physical quantity related to the target friction braking force is the gain set according to the reliability of the calculation result resulting from the magnitude of the target friction braking force, and the gain set according to the reliability of the calculation result resulting from the magnitude of the target friction braking force, and a gain that is set according to the reliability of the calculation result due to the rate of change of the target frictional braking force;
Vehicle control device. The vehicle control device according to claim 9,
The gain that is set according to the reliability of the calculation result due to the magnitude of the target frictional braking force is higher as the target frictional braking force is larger;
The smaller the change rate, the higher the gain that is set depending on the reliability of the calculation result due to the rate of change of the target frictional braking force;
The gain set according to the reliability of the calculation result due to the temperature of the brake pad is higher as the amount of change in the temperature is smaller;
Vehicle control device to be set. The vehicle control device according to claim 10,
The evaluation gain is
The gain is set according to the reliability of the calculation result due to the magnitude of the target frictional braking force.
Obtained by selecting high of a gain set according to the reliability of the calculation result caused by the rate of change of the target frictional braking force and a gain set according to the reliability of the calculation result caused by the temperature of the brake pad. is set by multiplying the gain,
Vehicle control device. The vehicle control device according to claim 3,
The control section includes:
determining the correction gain based on a physical quantity related to the target frictional braking force, a driving force of the drive device, a longitudinal acceleration of the vehicle, a running resistance of the vehicle, and a weight of the vehicle;
Vehicle control device. A vehicle control method executed by a control unit mounted on the vehicle, which includes a friction braking device that generates a frictional braking force on the vehicle, and a drive device that generates a driving force on the vehicle, the method comprising:
The control unit includes:
obtaining a physical quantity related to a total braking force for decelerating the vehicle;
When decelerating the vehicle based on the physical quantity related to the target braking force, a control command is output to cause the drive device to generate a driving force while the frictional braking force is being generated.
correcting according to the reliability of the calculation result due to the state of the vehicle;
Vehicle control method. a friction braking device that generates frictional braking force on a vehicle;
a drive device that generates driving force for the vehicle;
A control device that outputs a calculation result based on input information,
The control device includes:
obtaining a physical quantity related to a total braking force for decelerating the vehicle;
When decelerating the vehicle based on the physical quantity related to the target braking force, a control command is output to cause the drive device to generate a driving force while the frictional braking force is being generated.
correcting according to the reliability of the calculation result due to the state of the vehicle;
a control device;
A vehicle control system equipped with

Images