Patent Description:
Document <CIT> discloses a vehicle equipped with a driving device, a braking device, and an autonomous driving controller that controls the driving device and the braking device so as to execute an autonomous driving control. The autonomous driving controller executes a feedback control of the driving device and the braking device in order to eliminate a deviation between a target acceleration and an actual acceleration.

During an execution of the above-described autonomous driving control, a state in which the driving device is operating, may be switched to a state in which the braking device operates. In such a case, the actual acceleration of the vehicle may fluctuate due to a difference in responsiveness between the driving device and the braking device. This may cause an occupant of the vehicle to experience discomfort.

The patent application <CIT> discloses a brake control device for vehicles capable of generating both regenerative and friction braking forces, wherein the device aims to address the issue of fluctuating vehicle deceleration during the transition from regenerative to friction braking modes.

It is the object of the invention, to provide a vehicle controller and a control method of a vehicle controller suitably meeting the above issues.

The object is achieved by a vehicle controller according to claim <NUM> and by a control method according to claim <NUM>. Advantageous embodiments are carried out according to the dependent claims.

According to the invention, a vehicle controller controls a driving device, which includes a motor-generator, and a braking device, which applies a frictional braking force to a vehicle, thereby automatically controlling a traveling speed of the vehicle. The vehicle controller includes a controlling unit. The controlling unit calculates a feedback control amount based on a deviation between a target acceleration of the vehicle and an actual acceleration of the vehicle. The controlling unit also executes a feedback control of the driving device and the braking device by using the feedback control amount, such that the deviation decreases. A state in which only the driving device, of the driving device and the braking device, operates is a first state. A state in which at least the braking device, of the driving device and the braking device, operates is a second state. When switched from the first state to the second state, the controlling unit calculates the feedback control amount such that the deviation permitted in the feedback control is greater than the deviation prior to a start of switching from the first state to the second state.

According to the invention, a vehicle control method controls a driving device, which includes a motor-generator, and a braking device, which applies a frictional braking force to a vehicle, thereby automatically controlling a traveling speed of the vehicle. The method includes: calculating a feedback control amount based on a deviation between a target acceleration of the vehicle and an actual acceleration of the vehicle; and executing a feedback control of the driving device and the braking device by using the feedback control amount, such that the deviation decreases. A state in which only the driving device, of the driving device and the braking device, operates is a first state. A state in which at least the braking device, of the driving device and the braking device, operates is a second state. The calculating the feedback control amount includes calculating, when switched from the first state to the second state, the feedback control amount such that the deviation permitted in the feedback control is greater than the deviation prior to a start of switching from the first state to the second state.

In this application, "at least one of A and B" should be understood to mean "only A, only B, or both A and B.

A vehicle controller according to one embodiment will now be described with reference to the drawings. The vehicle controller is a travel controller <NUM> in the present embodiment. In the present embodiment, the travel controller <NUM> is mounted on a vehicle <NUM>, which is a battery electric vehicle.

As shown in <FIG>, the vehicle <NUM> includes wheels <NUM>, braking mechanisms <NUM>, a driving device <NUM>, a braking device <NUM>, a driver assistance device <NUM>, the travel controller <NUM>, and a wheel speed sensor SE1. Some of the components of the vehicle <NUM> are omitted from <FIG>.

Each braking mechanism <NUM> includes a rotor <NUM>, which rotates integrally with the associated wheel <NUM>, frictional members <NUM>, which do not rotate integrally with the wheel <NUM>, a wheel cylinder <NUM>, which displaces the frictional members <NUM> toward the rotor <NUM> in accordance with a hydraulic pressure.

As the hydraulic pressure of the wheel cylinder <NUM> increases, the braking mechanism <NUM> presses the frictional members <NUM> to the rotor <NUM> with a greater force. As the force with which the frictional members <NUM> are pressed against the rotor <NUM> increases, the braking mechanism <NUM> applies a greater frictional braking force Fbf to the wheel <NUM>. The braking mechanism <NUM> are provided for the respective wheels <NUM>. For example, if the vehicle <NUM> is a four-wheel vehicle, the vehicle <NUM> is equipped with four wheels <NUM> and four braking mechanisms <NUM>.

The driving device <NUM> includes a motor-generator <NUM> and a drive controlling unit <NUM>, which controls the motor-generator <NUM>.

When the motor-generator <NUM> functions as an electric motor, the motor-generator <NUM> applies, to each wheel <NUM>, a driving force Fd for causing the vehicle <NUM> to travel. That is, the motor-generator <NUM> functions as a drive source of the vehicle <NUM>. When the motor-generator <NUM> functions as a generator, the motor-generator <NUM> generates power in accordance with the rotation speed of the wheels <NUM>. During generation of power, the motor-generator <NUM> applies, to the wheels <NUM>, a regenerative braking force Fbr, which decelerates the vehicle <NUM>.

The drive controlling unit <NUM> causes the motor-generator <NUM> to generate the driving force Fd based on a request driving force Fdq requested by the travel controller <NUM>. Also, the drive controlling unit <NUM> causes the motor-generator <NUM> to generate the regenerative braking force Fbr based on a request regenerative braking force Fbrq requested by the brake controlling unit <NUM>. For example, if the vehicle <NUM> is a four-wheel vehicle, the vehicle <NUM> preferably include a motor-generator for the front wheels and a motor-generator for the rear wheels.

The braking device <NUM> includes a brake actuator <NUM>, which adjusts a hydraulic pressure of the wheel cylinder <NUM>, and a brake controlling unit <NUM>, which controls the brake actuator <NUM>.

The brake actuator <NUM> adjusts the amount of brake fluid supplied to the wheel cylinder <NUM> so as to adjust the hydraulic pressure of the wheel cylinder <NUM>. The brake actuator <NUM> is preferably capable of adjusting the hydraulic pressure of each of wheel cylinders <NUM> that respectively correspond to the wheels <NUM>. Due to the need for adjustment of the hydraulic pressure, the braking device <NUM> has a lower responsiveness than that of the driving device <NUM>. It is now assumed, by way of example, step functions of the same magnitude are input to the driving device <NUM> and the braking device <NUM> as command values. In this case, the driving device <NUM> has a short response delay until it produces the regenerative braking force Fbr, which corresponds to the magnitude of the step function. In contrast, the braking device <NUM> tends to have a longer response delay until it produces the frictional braking force Fbf, which corresponds to the magnitude of the step function.

The brake controlling unit <NUM> divides a request braking force Fbq into the regenerative braking force Fbr and the frictional braking force Fbf. Specifically, based on the request braking force Fbq, which is requested by the travel controller <NUM>, the brake controlling unit <NUM> calculates a request regenerative braking force Fbrq to be produced by the motor-generator <NUM>, and a request frictional braking force Fbfq to be produced by the brake actuator <NUM>. The brake controlling unit <NUM> causes the brake actuator <NUM> to generate the frictional braking force Fbf based on the request frictional braking force Fbfq, while it sends a request for the request regenerative braking force Fbrq to the drive controlling unit <NUM>.

When the motor-generator <NUM> is capable of producing the regenerative braking force Fbr, the brake controlling unit <NUM> increases a ratio α of the request regenerative braking force Fbrq to the request braking force Fbq in order to increase the recovery efficiency of regenerative energy. On the other hand, when the vehicle <NUM> is about to stop with brake being applied to the vehicle <NUM>, the brake controlling unit <NUM> executes a replacement control that replaces the regenerative braking force Fbr with the frictional braking force Fbf. In the replacement control, the brake controlling unit <NUM> gradually reduces the magnitude of the request regenerative braking force Fbrq and gradually increases the magnitude of the request frictional braking force Fbfq.

The ratio α prior to the execution of the replacement control is less than or equal to <NUM>% and greater than <NUM>%. The ratio α gradually decreases during the replacement control. The ratio α after the replacement control is less than the ratio α prior to the replacement control. For example, the execution of the replacement control changes the ratio α from <NUM>% to <NUM>%. The replacement control is preferably started, for example, when a vehicle speed Vb falls below a specific speed Vbth and finished before the vehicle speed Vb becomes <NUM>. In another embodiment, the ratio α may be reduced in a stepwise manner.

The brake controlling unit <NUM> delivers, to the travel controller <NUM>, a frictional braking intervention flag FLG, which indicates whether the frictional braking force Fbf is being applied to the vehicle <NUM>. The frictional braking intervention flag FLG is set to ON during a period in which the frictional braking force Fbf is applied to the vehicle <NUM>, and is set to OFF during a period in which the frictional braking force Fbf is not applied to the vehicle <NUM>.

When the replacement control is executed, a state of the driving device <NUM> and the braking device <NUM> is switched from a first state to a second state. The first state is a state in which only the driving device <NUM>, of the driving device <NUM> and the braking device <NUM>, is activated. The second state is a state in which at least the braking device <NUM>, of the driving device <NUM> and the braking device <NUM>, is activated. The first state is a state prior to the start of the replacement control. Specifically, the first state is a state in which the braking device <NUM> is not applying the frictional braking force Fbf to the vehicle <NUM>, while the driving device <NUM> is applying the regenerative braking force Fbr to the vehicle <NUM>. The second state includes a state in which the replacement control is being executed. Specifically, the second state includes a state in which the magnitude of the force produced by the driving device <NUM> is less than that in the first state and the magnitude of the force produced by the braking device <NUM> is greater than that in the first state. In other words, the second state includes a state in which the magnitude of the regenerative braking force Fbr, which is produced by the driving device <NUM>, is less than that prior to the start of the replacement control, and the magnitude of the frictional braking force Fbf, which is produced by the braking device <NUM>, is greater than that prior to the start of the replacement control. In the present embodiment, the first state corresponds to a state in which the frictional braking intervention flag FLG is OFF, and the second state corresponds to a state in which the frictional braking intervention flag FLG is ON.

The driver assistance device <NUM> executes an autonomous driving control to cause the vehicle <NUM> to travel autonomously. As shown in <FIG> and <FIG>, the driver assistance device <NUM> calculates a request value Rc used in the autonomous driving control based on various types of driving information. In the present embodiment, the request value Rc is a request value of a longitudinal force that indicates a force that acts in the longitudinal direction of the vehicle <NUM>. When having a positive value, the request value Rc indicates that the driver assistance device <NUM> is requesting acceleration of the vehicle <NUM>. When having a negative value, the request value Rc indicates that the driver assistance device <NUM> is requesting deceleration of the vehicle <NUM>. Also, the driving information includes, for example, information related to the position of the vehicle <NUM>, information related to the environment of the vehicle <NUM>, and information related to the traveling state of the vehicle <NUM>.

As shown in <FIG>, the travel controller <NUM> includes a target acceleration calculating unit <NUM>, an actual acceleration calculating unit <NUM>, an acceleration deviation calculating unit <NUM>, a feedback controlling unit <NUM>, a converting unit <NUM>, and a longitudinal force controlling unit <NUM>. The feedback controlling unit <NUM> corresponds to one example of a control unit, and includes a dead band setting unit <NUM>, a PI controlling unit <NUM>, and a change amount limiting unit <NUM>. The travel controller <NUM> controls the driving device <NUM> and the braking device <NUM> based on the request value Rc of the driver assistance device <NUM>, thereby automatically control the traveling speed of the vehicle <NUM>.

The target acceleration calculating unit <NUM> calculates a target acceleration G of the vehicle <NUM> based on the request value Rc of the driver assistance device <NUM>. Specifically, the target acceleration calculating unit <NUM> converts the request value Rc, which is a longitudinal force, into the dimension of acceleration, so as to calculate the target acceleration Gt. The target acceleration Gt has a positive value when acceleration of the vehicle <NUM> is requested. The target acceleration Gt has a negative value when deceleration of the vehicle <NUM> is requested.

The actual acceleration calculating unit <NUM> calculates a wheel speed Vw and the vehicle speed Vb based on a detection result of the wheel speed sensor SE1. The actual acceleration calculating unit <NUM> then performs temporal differentiation of the vehicle speed Vb, thereby calculating the actual acceleration of the vehicle <NUM>. In the following description, the actual acceleration of the vehicle <NUM> is labeled as Ga.

The acceleration deviation calculating unit <NUM> subtracts the actual acceleration Ga, which is calculated by the actual acceleration calculating unit <NUM>, from the target acceleration Gt, which is calculated by the target acceleration calculating unit <NUM>, thereby calculating a deviation hG between the accelerations.

The dead band setting unit <NUM> of the feedback controlling unit <NUM> sets a dead band in a range that includes the value <NUM> of the acceleration deviation hG, which is calculated by the acceleration deviation calculating unit <NUM>. In the following description, the deviation after the dead band is set will be referred to as a deviation hH to be distinguished from the deviation hG before the dead band is set.

The dead band setting unit <NUM> sets the deviation hH to <NUM> when the deviation hG is within the dead band. The dead band setting unit <NUM> sets the deviation hH to a positive value when the deviation hG is greater than the upper limit of the dead band. Specifically, the dead band setting unit <NUM> increases the deviation hH as the deviation hG increases when the deviation hG is greater than the upper limit of the dead band. In contrast, the dead band setting unit <NUM> sets the deviation hH to a negative value when the deviation hG is less than the lower limit of the dead band. Specifically, the dead band setting unit <NUM> reduces the deviation hH as the deviation hG decreases when the deviation hG is less than the lower limit of the dead band.

The dead band setting unit <NUM> sets a width Wh of the dead band to a first width Wh1 when the frictional braking intervention flag FLG is OFF. Also, the dead band setting unit <NUM> sets the width Wh of the dead band to a second width Wh2, which is wider than the first width Wh1, when the frictional braking intervention flag FLG is ON. The first width Wh1 corresponds to the responsiveness of the driving device <NUM> and is narrower than a width that corresponds to the responsiveness of the braking device <NUM>. On the other hand, the second width Wh2 corresponds to the responsiveness of the braking device <NUM>. In this manner, when switched from the first state, in which only the driving device <NUM> operates, to the second state, in which at least the braking device <NUM> operates, the dead band setting unit <NUM> causes the width Wh of the dead band to be wider than the width prior to the start of the switching.

In <FIG>, a solid line represents the relationship between the deviation hH and the deviation hG in a case in which the frictional braking intervention flag FLG is OFF. A broken line represents the relationship between the deviation hH and the deviation hG in a case in which the frictional braking intervention flag FLG is ON.

The PI controlling unit <NUM> of the feedback controlling unit <NUM> calculates a feedback control amount Si, which is used to reduce the deviation hH. That is, the feedback control amount Si is calculated through a feedback control that uses the deviation hH as an input. In the present embodiment, the feedback control includes a proportional control and an integral control. The feedback control amount Si is thus obtained by adding the product of the proportional gain Kp and the deviation hH to the product of an integral gain Ki and the time integral of the deviation hH.

The change amount limiting unit <NUM> of the feedback controlling unit <NUM> sets a limit to a temporal change amount dS, which is a change amount per unit time of the feedback control amount Si, which is calculated by the PI controlling unit <NUM>. That is, the change amount limiting unit <NUM> is a rate limiter that uses the feedback control amount Si as an input, and outputs a feedback control amount Sh. When the feedback control amount Si changes in a stepwise manner as indicated by a solid line in <FIG>, the temporal change amount dS of the feedback control amount Sh is reduced as indicated by a long-dash short-dash line and a long-dash double-short-dash line.

When the frictional braking intervention flag FLG is OFF, the change amount limiting unit <NUM> sets the upper limit of the temporal change amount dS of the feedback control amount Si to a first upper limit dS1. The long-dash short-dash line in the change amount limiting unit <NUM> shown in <FIG> represents the first upper limit dS1. When the frictional braking intervention flag FLG is ON, the change amount limiting unit <NUM> sets the upper limit of the temporal change amount dS of the feedback control amount Si to a second upper limit dS2, which has a smaller gradient than the first upper limit dS1. The long-dash double-short-dash line in the change amount limiting unit <NUM> shown in <FIG> represents the second upper limit dS2. In this manner, the change amount limiting unit <NUM> sets the temporal change amount dS of the feedback control amount Sh to a smaller value when the frictional braking intervention flag FLG is ON than when the frictional braking intervention flag FLG is OFF. In other words, when switched from the first state, in which only the driving device <NUM> operates, to the second state, in which at least the braking device <NUM> operates, the change amount limiting unit <NUM> causes the temporal change amount dS of the feedback control amount Sh to be smaller than the temporal change amount dS prior to the start of the switching.

The first upper limit dS1 and the second upper limit dS2 are set to positive values when the temporal change amount dS of the feedback control amount Si has a positive value, and are set to negative values when the temporal change amount dS of the feedback control amount Si has a negative value. In this respect, the change amount limiting unit <NUM> limits the temporal change amount dS of the feedback control amount Si by reducing the gradient of change in the feedback control amount Si in relation to the time elapsed.

The converting unit <NUM> converts the feedback control amount Sh, of which the change amount is limited by the change amount limiting unit <NUM>, into the same dimension as the request value Rc. In the present embodiment, the converting unit <NUM> converts the feedback control amount Sh, which is in the dimension of acceleration, into a feedback control amount in the dimension of longitudinal force. In the following description, the feedback control amount after the conversion will be referred to as a compensation value Rh.

The longitudinal force controlling unit <NUM> controls the driving device <NUM> and the braking device <NUM> based on the sum of the request value Rc and the compensation value Rh. In the following description, the sum of the request value Rc and the compensation value Rh will be referred to as a corrected request value Rd. When the corrected request value Rd has a positive value, the longitudinal force controlling unit <NUM> requests the driving device <NUM> to generate the request driving force Fdq that corresponds to the magnitude the corrected request value Rd. In this case, the driving force Fd that corresponds to the request driving force Fdq is applied to the vehicle <NUM>. In contrast, when the corrected request value Rd has a negative value, the longitudinal force controlling unit <NUM> requests the braking device <NUM> to generate the request braking force Fbq that corresponds to the magnitude of the corrected request value Rd. In this case, the braking force Fb is applied to the vehicle <NUM> such that the sum of the regenerative braking force Fbr and the frictional braking force Fbf is equal to the request braking force Fbq.

With reference to <FIG>, changes in various parameters during the execution of the replacement control will be described.

As shown in <FIG>, the braking force Fb is applied to the vehicle <NUM> when the target acceleration Gt has a negative value. Since the target acceleration Gt is constant, that is, since the request braking force Fbq is constant, the vehicle speed Vb gradually decreases.

At a first point in time t11, at which the vehicle speed Vb is greater than the determination speed Vbth, the braking force Fb applied to the vehicle <NUM> includes only the regenerative braking force Fbr, so that the frictional braking intervention flag FLG is OFF. Thus, at the first point in time t11, the width Wh of the dead band is the first width Wh1, and the upper limit of the temporal change amount dS of the feedback control amount Si is the first upper limit dS1.

When the vehicle speed Vb becomes equal to the determination speed Vbth at a second point in time t12 due to the decrease in the vehicle speed Vb, the replacement control is started. That is, the frictional braking intervention flag FLG is set to ON at the second point in time t12. The replacement control gradually reduces the magnitude of the regenerative braking force Fbr and gradually increases the magnitude of the frictional braking force Fbf. In other words, the ratio α of the regenerative braking force Fbr gradually decreases. Since the replacement control is started at the second point in time t12, the second point in time t12 corresponds to a point in time at which the state of the driving device <NUM> and the braking device <NUM> is switched from the first state, in which only the driving device <NUM> operates, to the second state, in which at least the braking device <NUM> operates.

As described above, the braking device <NUM> has a lower responsiveness than that of the driving device <NUM>. Accordingly, during the execution of the replacement control, the request regenerative braking force Fbrq and the regenerative braking force Fbr, which is produced by the driving device <NUM>, are unlikely to deviate from each other. In contrast, during the execution of the replacement control, the request frictional braking force Fbfq and the frictional braking force Fbf, which is produced by the braking device <NUM>, are likely to deviate from each other. Thus, the actual acceleration Ga of the vehicle <NUM> may fluctuate periodically if a feedback control is executed to compensate for the deviation hG, which is produced by the responsiveness of the braking device <NUM> during the execution of the replacement control.

In this regard, the present embodiment sets the width Wh of the dead band to the second width Wh2, which is wider than the first width Wh1, when the frictional braking intervention flag FLG is set to ON at the second point in time t12. As a result, the deviation hH is likely to become <NUM> when the deviation hG has a value near <NUM>. Thus, when the feedback control amount Si is calculated using the deviation hH, the proportional term is likely to become <NUM>, and the absolute value of the feedback control amount Si is unlikely to increase. Since the frictional braking force Fbf and the regenerative braking force Fbr are adjusted based on the feedback control amount Si, the actual acceleration Ga of the vehicle <NUM> is prevented from fluctuating periodically during the execution of the replacement control.

Also, during the execution of the replacement control, the feedback control amount Si may be changed abruptly in order to eliminate the deviation hG. In such a case, a jerk, which is the temporal change amount of the actual acceleration Ga, may become excessive, impairing the ride comfort of the vehicle <NUM>. Further, during the execution of the replacement control, if the responsiveness of the brake actuator <NUM> to a sudden change in the feedback control amount Si is low, the request frictional braking force Fbfq and the frictional braking force Fbf may deviate from each other.

In this regard, when the frictional braking intervention flag FLG is set to ON, the present embodiment sets the upper limit of the temporal change amount dS of the feedback control amount Si to the second upper limit dS2, which is lower than the first upper limit dS1. This prevents the jerk from being excessive, and the ride comfort of the vehicle <NUM> is unlikely to be impaired. Also, since the change amount of the feedback control amount Sh, which is used to set the request braking force Fbq, is unlikely to increase, the request frictional braking force Fbfq and the frictional braking force Fbf are prevented from deviating from each other even if the responsiveness of the brake actuator <NUM> is low.

At a third point in time t13, at which the vehicle speed Vb is greater than <NUM>, the braking force Fb applied to the vehicle <NUM> includes only the frictional braking force Fbf. That is, the replacement control is completed at the third point in time t13 before the vehicle <NUM> stops. However, since the frictional braking intervention flag FLG is still ON, the width Wh of the dead band is maintained at the second width Wh2 after the third point in time t13, so that the upper limit of the temporal change amount dS of the feedback control amount Si is maintained at the second upper limit dS2. Thereafter, the vehicle <NUM> stops at a fourth point in time t14, at which the vehicle speed Vb becomes <NUM>.

In the case illustrated by <FIG>, the braking device <NUM> applies the frictional braking force Fbf to the vehicle <NUM> not only during the execution of the replacement control from the second point in time t12 to the third point in time t13, but also in a period after the third point in time t13, that is, in a period after the completion of the replacement control. The state after the second point in time t12 thus corresponds to the second state.

As described above, when the replacement control is started, the feedback control amount Sh is calculated such that the deviation hG, which is permitted in the feedback control, is greater than that prior to the start of the replacement control. That is, when switched from the first state, in which only the driving device <NUM> operates, to the second state, in which at least the braking device <NUM> operates, the feedback control amount Sh is calculated such that the deviation hG, which is permitted in the feedback control, becomes greater than that prior to the start of the switching. This prevents fluctuation of the actual acceleration Ga and thus prevents the occupant of the vehicle <NUM> from experiencing discomfort. Accordingly, the ride comfort of the vehicle <NUM> is improved.

The above-described embodiment may be modified as follows. The above-described embodiment and the following modifications can be combined as long as the combined modifications remain technically consistent with each other.

If a state in which the target acceleration Gt is <NUM> continues in the travel controller <NUM>, a state in which the driving device <NUM> applies the driving force Fd to the vehicle <NUM> and a state in which the braking device <NUM> applies the braking force Fb to the vehicle <NUM> may be switched back and forth at short intervals. In other words, the first state, in which only the driving device <NUM> operates, and the second state, in which at least the braking device <NUM> operates, are repeated at short intervals. The first state refers to a state in which the driving device <NUM> applies the driving force Fd to the vehicle <NUM>. The second state refers to a state in which the magnitude of the driving force Fd applied to the vehicle <NUM> by the driving device <NUM> is less than that in the first state, and the magnitude of the frictional braking force Fbf applied to the vehicle <NUM> by the braking device <NUM> is greater than that in the first state.

When switched from the first state to the second state, the travel controller <NUM> may calculate the feedback control amount Sh such that the deviation hG, which is permitted in the feedback control, is greater than that prior to the start of the switching. Specifically, when switched from the first state to the second state, the travel controller <NUM> may cause the width Wh of the dead band to be wider than the width Wh prior to the switching or cause the temporal change amount dS of the feedback control amount Si to be smaller than the temporal change amount prior to the switching. In this manner, the switching from the first state to the second state includes an operation that accompanies a reduction in the magnitude of the driving force Fd and an increase in the magnitude of the frictional braking force Fbf.

The replacement control does not necessarily need to be continued until the regenerative braking force Fbr at the start of the replacement control is entirely replaced by the frictional braking force Fbf. In other words, the replacement control may be modified as long as it replaces at least part of the regenerative braking force Fbr at the start of the replacement control with the frictional braking force Fbf.

During the execution of the replacement control, the request braking force Fbq does not necessarily need to be constant.

The request value Rc of the driver assistance device <NUM> may be modified as long as it is a value that correlates with the longitudinal force. For example, the request value Rc of the driver assistance device <NUM> may be an acceleration. In this case, the travel controller <NUM> does not need to calculate the target acceleration Gt and thus does not need to include the target acceleration calculating unit <NUM>. Also, the travel controller <NUM> does not need to convert the dimension of the feedback control amount Si and thus does not need to include the converting unit <NUM>.

The dead band setting unit <NUM> may set a dead band when the frictional braking intervention flag FLG is ON, and does not necessarily need to set a dead band when the frictional braking intervention flag FLG is OFF.

The dead band setting unit <NUM> does not necessarily need to change the width Wh of the dead band from the first width Wh1 to the second width Wh2 in a stepwise manner when the frictional braking intervention flag FLG is set to ON from OFF. For example, the dead band setting unit <NUM> may gradually change the width Wh of the dead band from the first width Wh1 to the second width Wh2. The same applies to a case in which the frictional braking intervention flag FLG is set to OFF from ON.

In a case in which the deviation hG increases, the dead band setting unit <NUM> may change the width Wh of the dead band back to the first width Wh1 even after setting the width Wh of the dead band to the second width Wh2. The case in which the magnitude of the deviation hG increases refers to a case in which the deviation hG is greater than a specific value or a case in which the deviation hG remains outside the first width Wh1 but within the second width Wh2 for a specific period of time. When the width Wh of the dead band is changed back to the first width Wh1, the integral term is preferably reset.

The change amount limiting unit <NUM> may set a limit to the temporal change amount dS of the feedback control amount Si when frictional braking intervention flag FLG is ON, and does not necessarily need to set a limit to the temporal change amount dS of the feedback control amount Si when the frictional braking intervention flag FLG is OFF.

The change amount limiting unit <NUM> does not necessarily need to change the upper limit of the temporal change amount dS of the feedback control amount Si from the first upper limit dS1 to the second upper limit dS2 in a stepwise manner when the frictional braking intervention flag FLG is set to ON from OFF. For example, the change amount limiting unit <NUM> may gradually change the upper limit of the temporal change amount dS from the first upper limit dS1 to the second upper limit dS2. The same applies to a case in which the frictional braking intervention flag FLG is set to OFF from ON.

In a case in which the deviation hG increases, the change amount limiting unit <NUM> may change the upper limit of the temporal change amount dS of the feedback control amount Si back to the first upper limit dS1 even after setting the upper limit of the temporal change amount dS of the feedback control amount Si to the second upper limit dS2. When the upper limit of the temporal change amount dS of the feedback control amount Si is changed back to the first upper limit dS1, the integral term is preferably reset.

In some cases, when the target acceleration Gt has a negative value and its absolute value is large, the frictional braking force Fbf as well as the regenerative braking force Fbr is applied to the vehicle <NUM>. In other words, both of the driving device <NUM> and the braking device <NUM> operate in some cases. In this case, the state prior to the start of the replacement control is regarded as the second state. Thus, the dead band setting unit <NUM> preferably sets the width Wh of the dead band to the second width Wh2, and the change amount limiting unit <NUM> preferably sets the upper limit of the temporal change amount dS of the feedback control amount Si to the second upper limit dS2. Therefore, the feedback controlling unit <NUM> does not need to change the width Wh of the dead band or the temporal change amount dS of the feedback control amount Si even if the replacement control is started.

In place of the brake controlling unit <NUM>, the longitudinal force controlling unit <NUM> may divide the request braking force Fbq into the regenerative braking force Fbr and the frictional braking force Fbf. In this case, the longitudinal force controlling unit <NUM> requests the driving device <NUM> to generate the request regenerative braking force Fbrq, and requests the braking device <NUM> to generate the request frictional braking force Fbfq.

The travel controller <NUM> may include at least one of the dead band setting unit <NUM> and the change amount limiting unit <NUM>.

In the above-described embodiment, the request value Rc, which is a feedforward term, and the compensation value Rh, which is a feedback term, are used to set the request braking force Fbq and the request driving force Fdq. However, the present invention is not limited to this. If the compensation value Rh is used to set the request braking force Fbq and the request driving force Fdq, only the compensation value Rh of the request value Rc and the compensation value Rh may be used to set the request braking force Fbq and the request driving force Fdq.

The braking mechanism <NUM> may generate the frictional braking force Fbf by pressing the frictional members <NUM> against the wheel <NUM> as in a case of a drum brake.

The number of the wheels <NUM> of the vehicle <NUM> may be changed. For example, the vehicle <NUM> may be a two-wheel vehicle or a four-wheel vehicle.

The travel controller <NUM> is not limited to processing circuitry that includes a CPU and a ROM and executes software processing. For example, the travel controller <NUM> may include a dedicated hardware circuit that executes at least part of the processes executed in the above-described embodiment. The dedicated hardware circuits include, for example, an application specific integrated circuit (ASIC). That is, the travel controller <NUM> may be modified as long as it has any one of the following configurations (a) to (c).

Multiple software processing devices each including a processor and a program storage device and multiple dedicated hardware circuits may be provided.

Claim 1:
A vehicle controller (<NUM>) that controls a driving device (<NUM>), which includes a motor-generator (<NUM>), and a braking device (<NUM>), which applies a frictional braking force to a vehicle (<NUM>), thereby automatically controlling a traveling speed of the vehicle (<NUM>), wherein
the vehicle controller comprises a controlling unit (<NUM>),
the controlling unit (<NUM>)
calculates a feedback control amount based on a deviation between a target acceleration (Gt) of the vehicle (<NUM>) and an actual acceleration (Ga) of the vehicle (<NUM>), and
executes a feedback control of the driving device (<NUM>) and the braking device (<NUM>) by using the feedback control amount, such that the deviation decreases,
a state in which only the driving device (<NUM>), of the driving device (<NUM>) and the braking device (<NUM>), operates is a first state,
a state in which at least the braking device (<NUM>), of the driving device (<NUM>) and the braking device (<NUM>), operates is a second state, and
is characterized in that
when switched from the first state to the second state, the controlling unit (<NUM>) calculates the feedback control amount such that the deviation permitted in the feedback control is greater than the deviation prior to a start of switching from the first state to the second state.