Vehicle and vehicle suspension control method

Abstract

To allow at least one of roll control and pitch control to be performed while achieving both of the responsibility of other requirements such as energy-saving.SOLUTION: A vehicle comprises: a first actuator; one or a plurality of second actuators; and an electronic control unit. The first actuator controls a suspension stroke of a control target wheel. The one or a plurality of second actuators control the suspension stroke and has the higher responsibility than the first actuator. The electronic control unit executes: calculation processing of calculating a request control amount required for at least one of roll control and pitch control of a vehicle; and command processing of distributing and commanding the request control amount to the first actuator and the one or a plurality of second actuators.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a vehicle including first and second actuators having different responsiveness from each other for controlling a suspension stroke, and a method for controlling a vehicle suspension. [Background technology]

[0002] Patent Document 1 discloses a technique for controlling active suspension based on information regarding the travel path of wheels received from an autonomous driving controller. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2018 / 0154723 Summary of the Invention [Problem to be solved by the invention]

[0004] The responsiveness required for an actuator used to control the suspension stroke varies depending on the purpose of use. For this reason, when an actuator mounted on a vehicle is used for vehicle attitude control (at least one of roll control and pitch control), if the actuator used has low responsiveness, it may be difficult to achieve attitude control at the expected level of responsiveness.

[0005] On the other hand, some highly responsive actuators, such as full-active actuators, basically continue to consume energy while performing attitude control, and are therefore not energy efficient. Also, some highly responsive actuators, such as semi-active actuators, have limited usable conditions. Therefore, when performing attitude control, it is desirable to balance responsiveness with other requirements, such as energy saving.

[0006] The present disclosure has been made in consideration of the above-mentioned problems, and has an object to provide a vehicle and a control method for a vehicle suspension that are capable of performing at least one of roll control and pitch control while satisfying other requirements such as energy saving and responsiveness. [Means for solving the problem]

[0007] A vehicle according to the present disclosure includes a first actuator, one or more second actuators, and an electronic control unit. The first actuator controls a suspension stroke of a controlled wheel. The one or more second actuators control the suspension stroke and have higher responsiveness than the first actuator. The electronic control unit executes a calculation process for calculating a required control amount required for at least one of roll control and pitch control of the vehicle, and a command process for distributing and commanding the required control amount to the first actuator and the one or more second actuators.

[0008] In the command processing, if a first maximum control amount, which is the maximum value of the first control amount that the first actuator can output, is insufficient for the required control amount, the electronic control unit may command the first maximum control amount to the first actuator, and may also command one of one or more second actuators a second control amount to compensate for the shortage.

[0009] The one or more second actuators may include a semi-active actuator that varies the damping force generated by the shock absorber to form a semi-active suspension, and a full-active actuator that forms a full-active suspension. In the command processing, when there is a first shortage of control amount with respect to a required control amount with only a first maximum control amount that is a maximum value of the first control amount that the first actuator can output, the electronic control unit may command the first actuator to the first maximum control amount, and may also command the semi-active actuator to a second control amount to compensate for the first shortage.

[0010] In the command processing, if a second shortage of control amount with respect to the required control amount remains with only a combination of the first maximum control amount and a second maximum control amount, which is the maximum value of the second control amount that can be output by the semi-active actuator, the electronic control unit may command the second maximum control amount to the semi-active actuator while commanding another second control amount to compensate for the second shortage.

[0011] In command processing, if the required control amount can be satisfied by only the first control amount of the first actuator, the electronic control unit may command the first actuator for all of the required control amount, and may not need to issue commands regarding the required control amount to one or more second actuators.

[0012] The present disclosure relates to a method for controlling a vehicle suspension, the method comprising: a first actuator for controlling a suspension stroke of a control target wheel; and one or more second actuators for controlling the suspension stroke and having higher responsiveness than the first actuator. The control method includes a calculation process for calculating a required control amount required for at least one of roll control and pitch control of the vehicle; a command process for distributing and commanding the required control amount to the first actuator and one or more second actuators; Includes. Effect of the Invention

[0013] According to the vehicle and vehicle suspension control method of the present disclosure, a first actuator and one or more second actuators having different responsiveness are combined to realize a required control amount required for at least one of roll control and pitch control, thereby making it possible to perform at least one of roll control and pitch control while satisfying responsiveness and other requirements such as energy saving. [Brief description of the drawings]

[0014] [Figure 1] 1 is a diagram illustrating an example of a configuration of a vehicle according to a first embodiment. [Diagram 2] FIG. 2 is a diagram illustrating an example of the configuration of the suspension illustrated in FIG. [Diagram 3] 5 is a flowchart showing an example of a process related to attitude control according to the first embodiment. [Figure 4] FIG. 11 is a diagram for explaining an example of a method for calculating a required control amount Xr for roll control and a required control amount Xp for pitch control. [Diagram 5] 4 is a time chart showing a schematic relationship between a required control amount X, a first maximum control amount X1max, and a second control amount X2. [Figure 6] 10 is a diagram illustrating an example of a configuration of a suspension provided on a vehicle according to a second embodiment. FIG. [Figure 7] 11 is a flowchart showing an example of a process related to attitude control according to the second embodiment. [Figure 8] 1 is a time chart showing a schematic relationship between a required control amount X, a first maximum control amount X1max, a second maximum control amount X21max, and a second control amount X22. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] In each embodiment described below, elements common to each drawing are given the same reference numerals, and duplicated explanations are omitted or simplified. Furthermore, when the number, quantity, amount, range, etc. of each element is mentioned in the embodiments described below, the technical idea of ​​the present disclosure is not limited to the mentioned number, unless otherwise specified or clearly specified in principle.

[0016] 1. First embodiment 1-1.Vehicle configuration 1 is a diagram illustrating an example of a configuration of a vehicle 1 according to the embodiment 1. The vehicle 1 is equipped with four wheels 10 (a left front wheel 10FL, a right front wheel 10FR, a left rear wheel 10RL, and a right rear wheel 10RR). The vehicle 1 is also equipped with an independent suspension 20.

[0017] 2 is a diagram showing a schematic example of the configuration of the suspension 20 shown in FIG. 1. The suspension 20 suspends each wheel 10 from the vehicle body 2, and includes a suspension arm 22, a shock absorber 24, an air spring 26, and an active actuator 28. The suspension arm 22 connects the wheel 10 to the vehicle body 2. The shock absorber 24 and the air spring 26 are interposed between the suspension arm 22 and the vehicle body 2. The vehicle body 2 and the shock absorber 24 and other members that are closer to the vehicle body 2 than the air spring 26 correspond to the sprung section 3. In contrast, the wheel 10 and the shock absorber 24 and other members that are closer to the wheel 10 than the air spring 26 correspond to the unsprung section 4.

[0018] The air spring 26 includes an air pump installed in the vehicle body 2. The air pump is, for example, electric. The pressure of the compressed air supplied to the inside of the air spring 26 is controlled by the ECU 30 described later. According to the air spring 26, a control force F1 according to the air pressure inside the air spring 26 can be generated as one of the control forces F acting between the sprung portion 3 and the unsprung portion 4. Then, by adjusting this air pressure to control the control force F1, the stroke S of the suspension 20 can be adjusted. By including the air spring 26, the suspension 20 constitutes an air suspension. The air spring 26 corresponds to an example of a "first actuator" according to the present disclosure, and is hereinafter also referred to as the "first actuator 26".

[0019] As an example, the active actuator 28 is disposed in parallel with the shock absorber 24 and the air spring 26, and is interposed between the suspension arm 22 and the vehicle body 2. The active actuator 28 is, for example, an electric or hydraulic type, and is configured to generate a control force F2, which is another one of the control forces F acting between the sprung portion 3 and the unsprung portion 4, based on a command from the ECU 30. The stroke S can be adjusted by controlling this control force F2. By including the active actuator 28, the suspension 20 constitutes an active suspension (more specifically, a fully active suspension). The active actuator 28 corresponds to an example of the "one or more second actuators" and the "fully active actuator" according to the present disclosure, and is hereinafter also referred to as the "second actuator 28".

[0020] Furthermore, the vehicle 1 is equipped with an electronic control unit (ECU) 30. The ECU 30 is equipped with a processor, a storage device, and an input / output interface. The input / output interface takes in sensor signals from sensors 32 attached to the vehicle 1, and outputs operation signals to the first actuator 26 and the second actuator 28. The storage device stores various control programs for controlling the actuators 26 and 28. The processor reads out and executes the control programs from the storage device, thereby realizing control of "air suspension" and "active suspension" using the actuators 26 and 28.

[0021] The sensors 32 include, for example, an acceleration sensor that detects the lateral acceleration and longitudinal acceleration acting on the vehicle 1, a sprung acceleration sensor that detects the vertical acceleration of the sprung mass 3, a suspension stroke sensor, and a wheel speed sensor provided on each wheel 10. The sensors 32 also include, for example, an accelerator position sensor and a brake position sensor that detect the amounts of depression of the accelerator pedal and the brake pedal, respectively, and a steering angle sensor of the steering wheel.

[0022] 1-2. Vehicle attitude control The above-mentioned first actuator (air spring) 26 functions as a suspension spring that absorbs shocks from the road surface, and can adjust the vehicle height of the vehicle 1 by controlling the stroke S. Therefore, the first actuator 26 corresponds to an example of a so-called "vehicle height adjustment device." Height adjustment by such a vehicle height adjustment device is performed for purposes such as lowering the vehicle height to make it easier for passengers to get on and off the vehicle, or lowering the vehicle height to reduce air resistance when the vehicle speed increases.

[0023] On the other hand, full active control can be performed by using the second actuator (active actuator) 28. Specifically, the second actuator 28 can be used for vibration control to improve ride comfort by suppressing vertical vibration of the sprung mass 3 associated with input from the road surface. Also, the second actuator 28 can be used for attitude control of the vehicle 1 (more specifically, roll control during turning associated with steering of the vehicle 1, and pitch control during acceleration and deceleration of the vehicle 1).

[0024] The responsiveness of the actuators 26 and 28, both of which can adjust the stroke S, differs depending on their respective basic intended uses. Specifically, the intended use of the first actuator 26 as a vehicle height adjustment device is as described above. For this reason, the first actuator 26 is not required to have high responsiveness in terms of adjusting the stroke S. On the other hand, the second actuator 28 is intended to be used for control requiring high responsiveness, such as the above-mentioned vibration control and attitude control, and is therefore configured to satisfy high responsiveness.

[0025] Therefore, the responsiveness of the second actuator 28 is higher than that of the first actuator 26. On the other hand, the second actuator 28, which is a fully active actuator, basically continues to consume energy during the execution of posture control, and has an aspect of poor energy efficiency. For this reason, if posture control (control of roll angle and pitch angle) is performed using only the second actuator 28, it is easy to ensure high control responsiveness, but energy consumption increases. Here, the first actuator 26, which serves as a vehicle height adjustment device, can also be used for posture control because the stroke S can be adjusted. However, it is difficult to always satisfy the responsiveness required for posture control by using only the first actuator 26.

[0026] Therefore, in the first embodiment, the ECU 30 executes the following "calculation process" and "command process" while using the first and second actuators 26 and 28 in combination for posture control. That is, the ECU 30 executes a calculation process to calculate a required control amount X required to realize roll control and pitch control of the vehicle 1. Then, the ECU 30 executes a command process to distribute the calculated required control amount X to the first actuator 26 and the second actuator 28 and issue a command to them.

[0027] More specifically, in the first embodiment, in the command processing, if the first maximum control amount X1max, which is the maximum value of the first control amount X1 that the first actuator 26 can output, is insufficient in terms of the control amount for the required control amount X, the ECU 30 commands the first maximum control amount X1max to the first actuator 26, and also commands the second actuator 28 to the second control amount X2 to compensate for the shortage.

[0028] On the other hand, when the required control amount X can be satisfied by only the first control amount X1, the ECU 30 commands the first actuator 26 to use the entire required control amount X as the first control amount X1, and does not command the second actuator 28 regarding the required control amount X.

[0029] Fig. 3 is a flowchart showing an example of a process related to attitude control according to embodiment 1. The process of this flowchart is repeatedly executed at predetermined time steps Δt (see Fig. 5) while the vehicle 1 is traveling. In Fig. 3, the processes of steps S100 and S102 correspond to an example of the above-mentioned "calculation process", and the processes of steps S104, S106, and S110 to S112 correspond to an example of the above-mentioned "command process".

[0030] <Step S100> In FIG. 3, the ECU 30 first acquires the lateral acceleration and the longitudinal acceleration acting on the vehicle 1 in step S100. More specifically, the ECU 30 estimates, for example, the lateral acceleration and the longitudinal acceleration at the next sample time (k+1) of the current sample time k in order to calculate the required control amount X in the next step S102. This estimation method is not particularly limited. For example, the lateral acceleration may be estimated based on information such as the vehicle speed and the steering angle. The longitudinal acceleration may be estimated based on, for example, required information of the vehicle longitudinal force (for example, required engine torque or required braking force). In addition, the lateral acceleration and the longitudinal acceleration may be estimated using, for example, a sprung acceleration sensor included in the sensors 32. Furthermore, in an example in which the vehicle 1 is an autonomous vehicle, the ECU 30 may receive information on the future lateral acceleration and the longitudinal acceleration from information acquired for path planning.

[0031] <Step S102> Next, in step S102, the ECU 30 calculates a required control amount X required for roll control and pitch control. The roll control here refers to control for generating control forces F1, F2 of one or both of the actuators 26 and 28 so as to cancel the roll generated during turning due to steering of the vehicle 1. More specifically, "canceling the roll" refers to suppressing the roll generated compared to the case without roll control, or generating a roll in the opposite direction to the generated roll. Similarly, the pitch control here refers to control for generating control forces F1, F2 of one or both of the actuators 26 and 28 so as to cancel the pitch generated during acceleration / deceleration of the vehicle 1. More specifically, "canceling the pitch" refers to suppressing the pitch generated compared to the case without pitch control, or generating a pitch in the opposite direction to the generated pitch.

[0032] Therefore, when both roll control and pitch control are performed, the required control amount X is the sum of the required control amount Xr for roll control and the required control amount Xp for pitch control. The required control amount Xr corresponds to the required value of the control force F required for roll control. The required control amount Xp corresponds to the required value of the control force F required for pitch control.

[0033] In step S102, the ECU 30 calculates the required control amounts Xr and Xp for each wheel 10. Then, the ECU 30 calculates the sum of the calculated required control amounts Xr and Xp as the required control amount X for each wheel 10.

[0034] In addition, at each wheel 10, the control force F (F1 and F2), which is the suspension generated force, is positive when it acts to lift the vehicle body 2 upward. Accordingly, the required control amount X (Xr and Xp) is also positive when it acts to lift the vehicle body 2 upward. Therefore, the required control amount Xr is positive for the wheel 10 on the outside of the turn and negative for the wheel 10 on the inside of the turn. Similarly, the required control amount Xp is negative for the front wheels 10FL and 10FR and positive for the rear wheels 10RL and 10RR during acceleration, and conversely, is positive for the front wheels 10FL and 10FR and negative for the rear wheels 10RL and 10RR during deceleration.

[0035] 4(A) and 4(B) are diagrams for explaining an example of a method for calculating the required control amount Xr for roll control and the required control amount Xp for pitch control, respectively. In step S102, ECU 30 calculates the required control amount Xr at the next sample time (k+1). The required control amount Xr is calculated by multiplying the lateral acceleration acquired in step S100 by a proportionality coefficient (gain). Therefore, as shown in FIG. 4(A), as the absolute value of the lateral acceleration increases, the absolute value of the required control amount Xr also increases. This proportionality coefficient corresponds to the slope of the straight line shown in FIG. 4(A) and is, for example, a value determined in advance.

[0036] Furthermore, ECU 30 calculates the required control amount Xp at the next sample time (k+1). Similarly, the required control amount Xp is calculated by multiplying the longitudinal acceleration acquired in step S100 by a proportionality coefficient (gain). Therefore, as shown in FIG. 4B, as the absolute value of the longitudinal acceleration increases, the absolute value of the required control amount Xp also increases. This proportionality coefficient corresponds to the gradient of the straight line shown in FIG. 4B, and is, for example, a value determined in advance.

[0037] In addition, the calculation method of the required control amount X is not particularly limited, and the required control amount X does not need to be based on the lateral acceleration and longitudinal acceleration acquired in step S100. In other words, the required control amount X to be distributed and commanded in the "command processing" according to the present disclosure may be one that can be used in at least one of the roll control and the pitch control. For this reason, the required control amount X may be calculated, for example, from virtual roll / pitch dynamic characteristics (e.g., spring constant and damping coefficient), or may be calculated based on other control laws or control theories.

[0038] <Step S104> Next, in step S104, the ECU 30 calculates a first maximum control amount X1max that can be output by the first actuator (air spring) 26. More specifically, the first maximum control amount X1max corresponds to the maximum first control amount X1 that can be output by the first actuator 26, including the time when the first control amount X1 changes over time. In step S104, the ECU 30 calculates the first maximum control amount X1max that can be output at the next sample time (k+1).

[0039] Here, the maximum change speed V1max and maximum value F1max (see FIG. 5) of the control force F1 that can be output by the first actuator 26 are basically determined by the specifications of the first actuator 26. Therefore, the maximum change speed V1max and maximum value F1max can be known in advance. The storage device of the ECU 30 stores information on the basic operating characteristics of the first actuator 26, such as the maximum change speed V1max and maximum value F1max. More specifically, the maximum change speed V1max corresponds to the maximum amount of change ΔF1max (see FIG. 5) per unit time (time step Δt).

[0040] FIG. 5 is a time chart that shows a schematic relationship between the required control amount X, the first maximum control amount X1max, and the second control amount X2. FIG. 5 shows an example of turning caused by steering the vehicle 1, but for the sake of simplicity, it is assumed that no change in longitudinal acceleration occurs due to acceleration or deceleration of the vehicle 1. That is, in FIG. 5, the required control amount Xp is treated as zero. Therefore, the required control amount Xr is equal to the required control amount X. The relationship shown in FIG. 5 is for the wheel 10 that is on the outside of the turn during turning. In the relationship for the wheel 10 that is on the inside of the turn during turning, the signs of the required control amount X and the first maximum control amount X1max are opposite to those in the relationship shown in FIG. 5.

[0041] In addition, when a change in longitudinal acceleration occurs during turning, the waveform of the required control amount X shown in Fig. 5 also changes due to a change in the required control amount Xp. However, the calculation of the first maximum control amount X1max and the second control amount X2 described below can be performed in the same manner as the example shown in Fig. 5 even when a change in longitudinal acceleration occurs regardless of whether or not turning is occurring.

[0042] In the example shown in Fig. 5, with the start of steering at the sample time (k = 0), the lateral acceleration increases over time, and the required control amount X increases accordingly. In this example, the vehicle then enters a steady circular turning state where the vehicle speed and lateral acceleration are constant, and the required control amount X remains constant over time. More specifically, Fig. 5 shows the required control amount X (solid line and dashed line) during two types of turning that differ in the lateral acceleration that occurs during the turning.

[0043] The first maximum control amount X1max of the first actuator 26 at each sample time k can be calculated based on, for example, the maximum change rate V1max and the maximum value F1max described above. Specifically, as shown in FIG. 5, first, the first maximum control amount X1max at the sample time (k=0) is zero. The first maximum control amount X1max at the next sample time (k=1) is calculated as the maximum change amount ΔF1max, which is the product of the maximum change rate V1max stored in the storage device and the time step Δt. The first maximum control amount X1max at each sample time k during the period from the next sample time (k=2) onwards until the first maximum control amount X1max reaches the maximum value F1max is calculated by adding the maximum change amount ΔF1max to the previous value. The first maximum control amount X1max after the first maximum control amount X1max reaches the maximum value F1max is calculated as the maximum value F1max. In addition, when the first maximum control amount X1max calculated in this manner is compared with the required control amount X indicated by the solid line, the time waveform of the first maximum control amount X1max corresponds to the time waveform obtained by rate-limiting the waveform of the required control amount X by the maximum change speed V1max and by upper-limit-limiting it by the maximum value F1max.

[0044] In the example shown in FIG. 5, the requested control amount X remains constant over time and then decreases toward 0. To realize the requested control amount X that changes in this way, the first control amount X1 must also decrease over time. The maximum rate of change when the first control amount X1 decreases (i.e., the slope of the time waveform of the first maximum control amount X1max) is V1max (a negative value). Therefore, for example, when the first control amount X1 is decreased from the sample time (k=m), the first maximum control amount X1max at each sample time k can be calculated by subtracting the negative maximum change amount ΔF1max from the previous value, in the same way as when the requested control amount X is increasing.

[0045] In addition, the information on the basic operating characteristics of the first actuator 26 stored in the storage device for calculating the first maximum controlled variable X1max may include information on dynamic characteristics such as dead time characteristics and first-order lag characteristics. The first maximum controlled variable X1max may be calculated taking into consideration, for example, one or both of the dead time characteristics and the first-order lag characteristics.

[0046] <Step S106> Next, in step S106, the ECU 30 determines whether or not the first maximum control amount X1max that the first actuator 26 can output is insufficient for the required control amount X. This determination can be made, for example, based on whether or not the difference ΔX1 is not 0. The difference ΔX1 is a value (=X-X1max) obtained by subtracting the first maximum control amount X1max calculated in step S104 from the required control amount X calculated in step S102.

[0047] Specifically, when the required control amount X increases over time as shown in Fig. 5, the required control amount X is greater than the first maximum control amount X1max, and so the above difference ΔX1 is positive. Also, as shown in the figure, when the required control amount X, which remains constant, is greater than the first maximum control amount X1max (maximum value F1max), the difference ΔX1 is positive. In this way, a positive difference ΔX1 means that the first maximum control amount X1max alone is insufficient to provide a control amount.

[0048] Furthermore, the "insufficient control amount" determined in step S106 also occurs when the difference ΔX1 is negative, as in the hatched area shown in Fig. 5. This hatched area occurs because, for example, the slope (solid line) of the required control amount X when it decreases due to a sudden return movement of the steering wheel by the driver of the vehicle 1 becomes larger than the slope of the first maximum control amount X1max. In this hatched area, the first maximum control amount X1max at each sample time k becomes larger than the required control amount X. That is, the difference ΔX1 becomes negative.

[0049] <Step S108> If the determination result in step S106 is No (i.e., there is no shortage of control amount), the process proceeds to step S108. For example, if the required control amount X is represented by a dashed line in FIG. 5, the determination result is No. In step S108, the ECU 30 commands the first actuator 26 to generate a first control amount X1 that is equal to the required control amount X calculated in step S102. As a result, the first actuator 26 is controlled to generate a control force F1 according to the commanded required control amount X.

[0050] <Step S110> On the other hand, if the result of the determination in step S106 is Yes (i.e., if there is a shortage of the control amount), the process proceeds to step S110. For example, if the required control amount X is represented by a solid line in FIG. 5, the result of this determination is Yes.

[0051] In step S110, the ECU 30 calculates a second controlled variable X2 which is a controlled variable of the second actuator (active actuator) 28. More specifically, the ECU 30 calculates the second controlled variable X2 at the next sample time (k+1). The second controlled variable X2 is calculated as a value required to compensate for the "deficiency of the controlled variable."

[0052] Specifically, the second control amount X2 is a value obtained by subtracting the first maximum control amount X1max calculated in step S104 from the required control amount X calculated in step S102, that is, the difference ΔX1. The reason is that, as illustrated in FIG. 5, when the difference ΔX1 is positive, it is necessary to increase the control force F2 of the second actuator 28 by the amount (difference ΔX1) that is insufficient with only the first maximum control amount X1max of the required control amount X. On the other hand, when the difference ΔX1 is negative, the control amount is insufficient by the negative difference ΔX1 with only the first maximum control amount X1max. For this reason, it is necessary to control the control force F2 of the second actuator 28 so as to decrease it by the negative difference ΔX1.

[0053] <Step S112> In step S112 following step S110, the ECU 30 commands the first actuator 26 to use the first maximum control amount X1max calculated in step S104 as the first control amount X1, and commands the second actuator 28 to use the second control amount X2 calculated in step S110. As a result, the first actuator 26 is controlled to generate a control force F1 corresponding to the commanded first maximum control amount X1max. Also, the second actuator 28 is controlled to generate a control force F2 corresponding to the commanded second control amount X2.

[0054] In addition, in the example shown in FIG. 5, if the slope of the required control amount X that starts to decrease from the sample time (k=m) is the same as or smaller than the slope of the first maximum control amount X1max (dashed line), then during the period in which the required control amount X is larger than the first maximum control amount X1max, the second control amount X2 can be reduced to zero over time from the sample time (k=m), and thereafter the required control amount X can be satisfied with only the first control amount X1.

[0055] 1-3.Effects As described above, the second actuator 28 has high responsiveness but consumes more energy than the first actuator 26. According to the vehicle 1 according to the first embodiment described above, a required control amount X required for roll control and pitch control is calculated. Then, the calculated required control amount X is distributed and commanded to the first actuator 26 and the second actuator 28. In this way, the first and second actuators 26, 28 having different responsiveness are used in combination to realize the required control amount X. This makes it possible to perform roll control and pitch control while satisfying both responsiveness and other requirements (energy saving in the case of the active actuator 28). This improves the comfort of the vehicle 1.

[0056] More specifically, according to the vehicle 1 according to the first embodiment, in the command process, when the first maximum control amount X1max that the first actuator 26 can output is insufficient for the control amount X relative to the required control amount X, the first maximum control amount X1max is commanded to the first actuator 26, and the second control amount X2 for compensating for the insufficiency is commanded to the second actuator 28. This makes it possible to use the first actuator 26 as a main actuator for roll control and pitch control, while compensating for the control amount for realizing the required control amount X by using the second actuator 28 as necessary. In particular, by using the second actuator 28, which has high responsiveness, as a sub actuator, it is possible to compensate for the response delay of the first actuator 26 when the required control amount X changes transiently (when it increases or decreases). This makes it possible to suitably bring the total control amount of the two actuators 26 and 28 close to the required control amount X during the transient period.

[0057] Furthermore, according to the vehicle 1 according to the first embodiment, when the required control amount X can be satisfied by only the first control amount X1, the entire required control amount X is commanded to the first actuator 26 as the first control amount X1, and no command regarding the required control amount X is issued to the second actuator 28. This makes it possible to suppress the frequency of use of the second actuator 28, which consumes a large amount of energy, while satisfying the required control amount X.

[0058] In addition, by using two types of actuators 26 and 28, the maximum control amount that each of the actuators 26 and 28 can output can be used as needed. As a result, a required control amount X that cannot be satisfied by using only one of the actuators 26 and 28 can be realized in roll control and pitch control. This improves the comfort of the vehicle 1.

[0059] In the above-described first embodiment, the active actuator (more specifically, the full-active actuator) 28 is used as the "second actuator" according to the present disclosure. However, instead of the active actuator 28, for example, an actuator of an active stabilizer device or a semi-active actuator 44 described in the following second embodiment may be used as the "second actuator", although the control force F that can be generated is limited.

[0060] 2. Second embodiment Vehicle 5 according to the second embodiment differs from vehicle 1 according to the first embodiment in the points described below.

[0061] 2-1.Vehicle configuration 6 is a diagram illustrating an example of the configuration of a suspension 40 provided on a vehicle 5 according to embodiment 2. The vehicle 5 is provided with a suspension 40. The suspension 40 differs from the suspension 20 according to embodiment 1 except that the suspension 40 is provided with a variable damping force shock absorber 42 instead of the shock absorber 24.

[0062] The variable damping force shock absorber 42 includes an actuator 44 that varies the damping force generated by the shock absorber 42. The suspension 40 includes the actuator 44, thereby forming a semi-active suspension. This damping force corresponds to a control force F3 generated by the shock absorber 42 so as to act between the sprung mass 3 and the unsprung mass 4. More specifically, the control force F3 (damping force) controlled by the actuator 44 is a resistance force against the expansion or contraction of the shock absorber 42. For this reason, the condition under which the damping force can be generated is limited to when the speed of the stroke S (stroke speed VS) is changing, for example, when the required control amount X is increasing or decreasing. For this reason, the active control (semi-active control) by the actuator 44 is more limited than the full active control by the second actuator 28. The actuator 44 corresponds to an example of the "second actuator" and the "semi-active actuator" according to the present disclosure.

[0063] 2-2. Vehicle attitude control As described above, the vehicle 5 according to the second embodiment includes two second actuators 28 and 44, namely, the fully active actuator 28 and the semi-active actuator 44. Similar to the second actuator 28, the second actuator 44 has higher responsiveness than the first actuator (air spring) 26. In addition, the second actuator (semi-active actuator) 44, which generates the control force F3 as a damping force, consumes less energy than the second actuator (fully active actuator) 28.

[0064] Therefore, in the second embodiment, the ECU 30 uses the first actuator 26 and the second actuators 28 and 44 for attitude control (roll control and pitch control) as follows: That is, in command processing, when the first maximum control amount X1max that the first actuator 26 can output is insufficient in the control amount for the required control amount X (hereinafter, for convenience, referred to as a "first shortage"), the ECU 30 commands the first actuator 26 to output the first maximum control amount X1max, and also commands the semi-active actuator 44, which is one of the second actuators, to output a second control amount X21 to make up for the first shortage.

[0065] In the second embodiment, if a shortage of control amount for the required control amount X remains with only a combination of the first maximum control amount X1max and the second maximum control amount X21max, which is the maximum value of the second control amount X21 that the semi-active actuator 44 can output, the ECU 30 commands the second maximum control amount X21max to the semi-active actuator 44, which is one of the second actuators. Furthermore, the ECU 30 commands the second control amount X22, which is another second control amount for compensating for the second shortage, to the fully active actuator 28, which is the other second actuator.

[0066] On the other hand, when the required control amount X can be satisfied by the first control amount X1 alone, the ECU 30 commands the first actuator 26 to use the entire required control amount X as the first control amount X1, and does not issue commands regarding the required control amount X to the second actuators 28 and 44. In addition, when there is a first shortage and the required control amount X can be satisfied by a combination of the first maximum control amount X1max and the second control amount X21, the ECU 30 distributes and commands the entire required control amount X to the first actuator 26 and the second actuator 44, and does not issue a command regarding the required control amount X to the other second actuator 28.

[0067] Fig. 7 is a flowchart showing an example of a process related to attitude control according to the second embodiment. The process of this flowchart differs from the process of the flowchart shown in Fig. 3 in that the following processes S200 to S210 are executed instead of the processes of steps S110 and S112. That is, in Fig. 7, the processes of steps S104, S106, and S200 to S210 correspond to an example of a "command process". Fig. 8 is a time chart that shows a schematic relationship between the required control amount X, the first maximum control amount X1max, the second maximum control amount X21max, and the second control amount X22. Fig. 8 illustrates an example of a turning operation, similar to Fig. 5.

[0068] <Step S200> In FIG. 7, if the determination result in step S106 is Yes (that is, if there is a "first shortage"), the process proceeds to step S200.

[0069] In step S200, the ECU 30 calculates a second maximum control amount X21max that can be output by the second actuator (semi-active actuator) 44. More specifically, in step S104, the ECU 30 calculates a second maximum control amount X21max that can be output at the next sample time (k+1).

[0070] As described above, the control force F3 (damping force) of the shock absorber 42 controlled by the second actuator 44 can be generated when the stroke speed VS is changing. The magnitude of the control force F3 (damping force) changes according to the stroke speed VS. Therefore, the relationship between the maximum control force F3MAX and the stroke speed VS in a state in which the second actuator 44 is controlled so that the control force F3 is maximized can be known in advance. The storage device of the ECU 30 stores such a relationship as a map. For example, the ECU 30 calculates the maximum control force F3MAX according to the stroke speed VS at the next sample time (k+1) from such a map, and uses it as the second maximum control amount X21max at the next sample time (k+1). In addition, when the stroke speed VS at the next sample time (k+1) is zero, the second maximum control amount X21max is calculated as zero.

[0071] The stroke speed Vs at the next sample time (k+1) can be estimated, for example, by using time-series data of the sensor value of the stroke sensor. In addition, for example, the response characteristic of the second actuator 44 for obtaining the maximum control force F3MAX may be taken into consideration in order to calculate the second maximum control amount X21max at each sample time k.

[0072] <Step S202> In step S202 following step S200, the ECU 30 determines whether or not a "second shortage" of the control amount for the required control amount X remains with only the combination of the first maximum control amount X1max and the second maximum control amount X21max. Specifically, this determination can be made based on, for example, whether or not a difference ΔX2 (=X-(X1max+X21max)) obtained by subtracting the sum of the first maximum control amount X1max and the second maximum control amount X21max from the required control amount X is not 0.

[0073] Specifically, FIG. 8 shows an example in which the second shortage occurs when the required control amount X increases over time. In the example shown in FIG. 8, the difference ΔX2 becomes positive, and the second shortage occurs. Although not shown in FIG. 8, the second shortage can also occur when the required control amount X suddenly decreases over time as illustrated in FIG. 5. At this time, the first maximum control amount X1max becomes larger than the required control amount X, and the second control amount X21 becomes a negative value (second maximum control amount X21max) to reduce the first shortage. Then, the difference ΔX2 becomes negative.

[0074] <Steps S204 and S206> If the determination result in step S202 is No (i.e., a first shortage occurs but the required control amount X can be satisfied by the combination of the first maximum control amount X1max and the second maximum control amount X21max, so that a second shortage does not remain), the process proceeds to step S204.

[0075] The processes of steps S204 and S206 are similar to the processes of steps S110 and S112 (see FIG. 3), respectively. That is, in step S204, the ECU 30 calculates a second control amount X21 of the second actuator 44 at the next sample time (k+1). The second control amount X21 is calculated as a value required to compensate for the "first shortage". That is, the second control amount X21 is the above-mentioned difference ΔX1 (positive or negative value).

[0076] In step S206 following step S204, the ECU 30 commands the first actuator 26 to use the first maximum control amount X1max calculated in step S104 as the first control amount X1, and commands the second actuator (semi-active actuator) 44 to use the second control amount X21 calculated in step S206.

[0077] <Step S208> On the other hand, if the determination result in step S202 is Yes (i.e., if the second shortage remains), the process proceeds to step S208. In step S208, the ECU 30 calculates the second control amount X22 of the second actuator 28 at the next sample time (k+1). The second control amount X22 is calculated as a value required to make up for the remaining "second shortage". In other words, the second control amount X22 is the above-mentioned difference ΔX2 (positive or negative value).

[0078] <Step S210> In step S210 following step S208, the ECU 30 commands the first actuator 26 to obtain the first maximum control amount X1max calculated in step S104 as the first control amount X1, and commands the second actuator (semi-active actuator) 44 to obtain the second maximum control amount X21max calculated in step S200 as the second control amount X21. Then, the ECU 30 commands the second actuator (fully active actuator) 28 to obtain the second control amount X22 calculated in step S208.

[0079] 2-3.Effects As described above, according to the vehicle 5 according to the second embodiment, when there is a "first shortage" in the control amount with only the first maximum control amount X1max, the first maximum control amount X1max is commanded to the first actuator 26, and the second control amount X21 for compensating for the first shortage is commanded to the semi-active actuator 44. Thus, according to the second embodiment, in the vehicle 5 including the two second actuators 28 and 44, the semi-active actuator 44 is actively used instead of the fully active actuator 28 to compensate for the lack of responsiveness of the main first actuator 26. This makes it possible to compensate for the lack of responsiveness of the first actuator 26 while reducing the energy consumption during a transient state. This makes it possible to more suitably achieve both responsiveness and energy saving.

[0080] Furthermore, in the vehicle 5 according to the second embodiment, when the combination of the first maximum control amount X1max and the second maximum control amount X21max alone leaves a "second shortage" in the control amount, the second control amount X22 for compensating for the second shortage is commanded to the fully active actuator 28. By using the two second actuators 28 and 44 in this order, it is possible to eliminate or at least reduce the second shortage while taking care to reduce energy consumption as much as possible.

[0081] 3. Other embodiments In the above-described first and second embodiments, the attitude control (roll control and pitch control) is performed on the four wheels 10 (i.e., all wheels) of the vehicle 1 or 5. However, the wheels that are the targets of the attitude control (control target wheels) are not necessarily limited to all wheels, and may be, for example, only the two front wheels or only the two rear wheels.

[0082] Also, unlike the above-described first and second embodiments, the attitude control to which the "calculation process" and "command process" according to the present disclosure are applied may be either roll control or pitch control.

[0083] Furthermore, in relation to the calculation of the first maximum control amount X1max of the first actuator 26, if the maximum value of the first maximum control amount X1max is increased to the maximum value F1max (see FIG. 5), the following problem occurs. That is, as illustrated in FIG. 5, when the required control amount X is suddenly decreased due to a sudden return operation of the steering wheel, the second actuator 28 is required to generate a control force F2 in the opposite direction to the control force F1 generated by the first actuator 26 in order to realize the required control amount X (hatched area in the figure). This is not preferable from the viewpoint of energy consumption. Therefore, in order to reduce the occurrence of such a situation in which a control force F2 in the opposite direction to the control force F1 is generated, the maximum value of the first maximum control amount X1max may be limited to be smaller than the maximum value F1max.

[0084] In addition, there are vehicles that can switch the vehicle driving mode between a "first driving mode (e.g., sports mode)" that emphasizes driving performance and a "second driving mode (e.g., comfort mode)" that emphasizes ride comfort over driving performance. For example, when the first mode is selected by the driver operating the mode change switch, it is considered that there is a high possibility that the steering wheel will be operated more frequently or the vehicle will be accelerated and decelerated more frequently than when the second driving mode is selected. Therefore, in order to reduce the occurrence of a control force F2 in the opposite direction to the control force F1, the ECU 30 may limit the maximum value of the first maximum control amount X1max to a smaller value when the first driving mode is selected than when the second driving mode is selected. [Explanation of symbols]

[0085] 1, 5 cars 2. Body 3. Spring 4 Unsprung mass 10 wheels 20, 40 Suspension 22 Suspension arm 24 Shock absorber 26 Air spring (first actuator) 28 Active actuator (second actuator; fully active actuator) 30 Electronic Control Unit (ECU) 32 Sensors 42 Variable damping force shock absorber 44 Actuator for variable damping force shock absorber (second actuator; semi-active actuator)

Claims

1. A first actuator that controls a suspension stroke of a controlled wheel; one or more second actuators that control the suspension stroke and have a higher responsiveness than the first actuators; An electronic control unit; A vehicle comprising: The electronic control unit includes: a calculation process for calculating a required control amount required for at least one of roll control and pitch control of the vehicle; a command process for distributing the required control amount to the first actuator and the one or more second actuators and issuing a command; Run The one or more second actuators a semi-active actuator that varies the damping force generated by the shock absorber and constitutes a semi-active suspension; A full active actuator that constitutes a full active suspension; Including, In the command processing, the electronic control unit: when a first maximum control amount, which is a maximum value of a first control amount that the first actuator can output, causes a first shortage of a control amount with respect to the required control amount, the first maximum control amount is commanded to the first actuator, and a second control amount for compensating for the first shortage is commanded to the semi-active actuator; When a second shortage of the control amount with respect to the required control amount remains only by a combination of the first maximum control amount and a second maximum control amount which is a maximum value of the second control amount which can be output by the semi-active actuator, the second maximum control amount is commanded to the semi-active actuator while another second control amount for compensating for the second shortage is commanded to the fully active actuator. A vehicle characterized by:

2. In the command process, when the required control amount can be satisfied by only the first control amount of the first actuator, the electronic control unit commands the first actuator for the entire required control amount, and does not issue a command regarding the required control amount to the one or more second actuators.

2. The vehicle according to claim 1 .

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