Vehicle control device

Abstract

To provide a vehicle control device that is able to stably assist in a vehicle's operation of riding over a step.SOLUTION: A vehicle control device is mounted in a vehicle including a drive unit that outputs torque to a drive wheel, a front suspension, and a rear suspension. The vehicle control device includes: acceleration detecting unit that detects an amount of operation of an accelerator; a vehicle speed estimating unit that estimates a vehicle speed; a front detecting unit that detects an amount of telescopic motion of the front suspension; a rear detecting unit that detects an amount of telescopic motion of the rear suspension; and a control unit that starts an assisting process including a torque increase process for increasing torque regardless of an increased proportion of the amount of accelerator operation when determining, based on a vehicle speed estimated by the vehicle speed estimating unit, movement of the vehicle corresponding to an amount of accelerator operation is stagnating. Then, based on detection results obtained by the front detection unit and the rear detection units, the control unit finishes the assisting process.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device. [Background technology]

[0002] Patent Document 1 describes a technology in which, when the vehicle approaches a step and its movement stops, a control unit increases torque to assist the vehicle in climbing up the step (FIG. 12). In this technology, the control unit ends the assistance based on the vehicle speed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-063122 Summary of the Invention [Problem to be solved by the invention]

[0004] When a vehicle goes up a bump, wheel spin may occur. When the control unit estimates the vehicle speed, the rotational speed of the wheels is used to calculate the vehicle speed. Therefore, if the assist is terminated based on the vehicle speed, as in the vehicle control of Patent Document 1, desirable vehicle behavior may not be obtained if wheel spin occurs while the vehicle is going up a bump.

[0005] An object of the present invention is to provide a vehicle control device that can stably assist a vehicle in climbing up a step. [Means for solving the problem]

[0006] One aspect of the present invention is A vehicle control device mounted on a vehicle including a drive unit that outputs torque to drive wheels, a front suspension, and a rear suspension, an accelerator detector that detects an accelerator operation amount; a vehicle speed estimation unit that estimates a vehicle speed; a front detection unit that detects the amount of expansion and contraction of the front suspension; a rear detection unit that detects the amount of expansion and contraction of the rear suspension; a control unit that starts an assist process including a torque increase process that increases the torque regardless of an increase rate of the accelerator operation amount when it is determined that the movement of the vehicle according to the accelerator operation amount is stagnating based on the vehicle speed estimated by the vehicle speed estimation unit; Equipped with The control unit Based on both the detection results of the front detection unit and the detection results of the rear detection unit at the same timing tree, After the difference between the amount of expansion and contraction detected by the front detection unit and the amount of expansion and contraction detected by the rear detection unit exceeds a predetermined threshold, if the absolute value of the difference between the amount of expansion and contraction detected by the front detection unit and the amount of expansion and contraction of the front suspension when running at a constant speed on flat ground becomes less than a first threshold, and if the absolute value of the difference between the amount of expansion and contraction detected by the rear detection unit and the amount of expansion and contraction of the rear suspension when running at a constant speed on flat ground becomes less than a second threshold, The assist process is terminated. [Effects of the Invention]

[0007] According to the present invention, the above-mentioned assist processing can assist the vehicle in climbing up a step. Furthermore, the control unit terminates the assist processing based on the amount of expansion and contraction of the front suspension detected by the front detection unit and the amount of expansion and contraction of the rear suspension detected by the rear detection unit. When the vehicle climbs up a step, the front suspension and the rear suspension exhibit characteristic behaviors, and the completion of climbing up the step can be reliably determined based on the detected values ​​of these expansion and contraction amounts. Therefore, the above-mentioned assist processing can reliably assist the vehicle in climbing up a step. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a block diagram showing a vehicle equipped with a vehicle control device according to an embodiment of the present invention. [Figure 2] 10 is a time chart illustrating an assist process for assisting a vehicle in climbing up a step. [Figure 3]4 is a flowchart showing an assist control process executed by the control unit. [Figure 4] 4 is a flowchart showing the procedure of the assist process in step S5 of FIG. 3. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described in detail with reference to the accompanying drawings. Fig. 1 is a block diagram showing a vehicle equipped with a vehicle control device according to an embodiment of the present invention.

[0010] The vehicle 1 equipped with the vehicle control device 100 of this embodiment is an electric vehicle such as an EV (Electric Vehicle) or HEV (Hybrid Electric Vehicle). The vehicle 1 includes front wheels 2 and rear wheels 3, a front suspension 4, a rear suspension 5, an electric motor 11 that generates driving force for the drive wheels, and a traction battery 12 that stores electric power for traveling. The vehicle 1 also includes an inverter 13 that drives the electric motor 11 using electric power from the traction battery 12, a driving operation unit 14 through which the driver performs driving operations, and a control unit 21 that controls the torque output from the electric motor 11. The following description will be given taking as an example a configuration in which the drive wheels are the front wheels 2, but the drive wheels may be the rear wheels 3, or both the front wheels 2 and the rear wheels 3.

[0011] The front suspension 4 is provided between the front wheel 2 and the vehicle body H, and provides a cushioning effect by expanding and contracting in accordance with the load applied between the front wheel 2 and the vehicle body H. The rear suspension 5 is provided between the rear wheel 3 and the vehicle body H, and provides a cushioning effect by expanding and contracting in accordance with the load applied between the rear wheel 3 and the vehicle body H.

[0012] The vehicle 1 further includes a front detection unit 22 that detects the amount of expansion and contraction of the front suspension 4, and a rear detection unit 23 that detects the amount of expansion and contraction of the rear suspension 5. The front detection unit 22 may be, for example, a linear sensor that measures the distance between two points (such as one end and the other end) of the front suspension. The outputs of the front detection unit 22 and the rear detection unit 23 are sent to the control unit 21.

[0013] The vehicle 1 further includes a plurality of wheel speed sensors 25 that detect the rotational speeds of the front wheels 2 and rear wheels 3, and an inertial sensor 26 that detects the rotational angular velocity and acceleration of the vehicle 1. The outputs of the plurality of wheel speed sensors 25 and the inertial sensor 26 are sent to the control unit 21.

[0014] The vehicle control device 100 according to this embodiment includes a front detection unit 22, a rear detection unit 23, a wheel speed sensor 25, an inertia sensor 26, an accelerator detection unit 141a, an assist operation unit 142, and a control unit 21.

[0015] The driving operation unit 14 includes an accelerator operation unit (e.g., an accelerator pedal) 141, an accelerator detection unit 141a that detects the amount of operation of the accelerator operation unit 141, and an assist operation unit 142 that can activate step climbing assist. The driving operation unit 14 further includes a brake operation unit (e.g., a brake pedal) 143, a brake detection unit 143a that detects the amount of operation of the brake operation unit 143, and a steering unit (e.g., a steering wheel) 144. The assist operation unit 142 is a switch (e.g., a paddle switch) provided in the steering unit, and is a switch that the driver can operate without removing their hands from the steering unit 144. Note that the assist operation unit 142 is not limited to the above switch, and may be an operation unit such as a button provided outside the steering unit 144.

[0016] The control unit 21 is an ECU (Electronic Control Unit) that includes a CPU (Central Processing Unit) that performs calculation processing, a RAM (Random Access Memory) into which the CPU expands data, a ROM (Read Only Memory) that stores a control program executed by the CPU, and an interface that transmits and receives signals between the CPU and devices external to the control unit 21. The control unit 21 may be composed of one ECU, or may be composed of multiple ECUs that communicate with each other and operate in cooperation.

[0017] In normal driving mode, the control unit 21 receives a signal indicating the accelerator operation amount output from the accelerator detection unit 141a, calculates a target torque according to driving operations, etc., and drives the electric motor 11 via the inverter 13 so as to obtain the target torque.

[0018] The control unit 21 also functions as a vehicle speed estimation unit that estimates the vehicle speed. The vehicle speed means the speed of the vehicle body H. The control unit 21 estimates the vehicle speed from the values ​​of the wheel speed sensors 25 of the front wheels 2 and the rear wheels 3 and the value of the inertial sensor 26. Considering the possibility of wheel spin on the front wheels 2 and the rear wheels 3, the control unit 21 may estimate the vehicle speed by ignoring the unbalanced value when multiple values ​​(first to fourth values) of the all-wheel speed sensors 25 of the front wheels 2 and the rear wheels 3 are not balanced. Alternatively, when the first value is not balanced, the control unit 21 may estimate the vehicle speed by correcting the first value based on the balanced second to fourth values ​​and the value of the inertial sensor 26.

[0019] The control unit 21 acquires the amounts of extension and contraction of the front suspension 4 and the rear suspension 5 based on the outputs of the front detection unit 22 and the rear detection unit 23. Furthermore, the control unit 21 stores values ​​of the reference amounts of extension and contraction of the front suspension 4 and the rear suspension 5.

[0020] The reference extension / contraction amount of the front suspension 4 refers to the extension / contraction amount of the front suspension 4 while traveling at a constant speed on flat ground (or while stopped). The reference extension / contraction amount of the rear suspension 5 refers to the extension / contraction amount of the rear suspension 5 while traveling at a constant speed on flat ground (or while stopped). The reference extension / contraction amount varies depending on the total weight of the vehicle body H including the passenger, so the control unit 21 stores the values ​​input from the front detection unit 22 and the rear detection unit 23 while traveling at a constant speed on flat ground as the reference extension / contraction amount. Alternatively, if the influence of the passenger weight on the extension / contraction amount is small, a value of the reference extension / contraction amount that ignores the passenger weight, or a value of the reference extension / contraction amount when an average passenger weight is added, may be calculated, and this value may be provided to the control unit 21, for example, during the manufacturing stage.

[0021] Although not particularly limited, in the following description, the control unit 21 treats the value obtained by subtracting the reference extension / contraction amount of the front suspension 4 from the extension / contraction amount value detected by the front detection unit 22 as the extension / contraction amount of the front suspension 4. This extension / contraction amount represents a relative extension / contraction amount when the reference extension / contraction amount of the front suspension 4 is set to zero, and this extension / contraction amount will be referred to as the "front extension / contraction amount" below. Similarly, in the following description, the control unit 21 treats the value obtained by subtracting the reference extension / contraction amount of the rear suspension 5 from the extension / contraction amount value detected by the rear detection unit 23 as the extension / contraction amount of the rear suspension 5. This extension / contraction amount represents a relative extension / contraction amount when the reference extension / contraction amount of the rear suspension 5 is set to zero, and this extension / contraction amount will be referred to as the "rear extension / contraction amount" below. When the extension / contraction amount is positive or negative, a positive value indicates an extension, and a negative value indicates a contraction.

[0022] The control unit 21 can execute an assist process to assist the vehicle 1 in climbing up the step f. The assist process is a control process that can realize ideal operation of the vehicle 1 when the vehicle 1 climbs up the step f without requiring skillful accelerator operation by the driver.

[0023] <Ideal vehicle behavior when climbing over bumps> 2 is a time chart illustrating an assist process for assisting the vehicle in climbing up a step. First, with reference to FIG. 2, an ideal operation when the vehicle 1 climbs up a step f will be described.

[0024] As shown in FIG. 2, when the vehicle 1 climbs up the step f, the front wheels 2 first approach the step f, causing the vehicle speed to drop to almost zero (timing t1). Then, during the subsequent period T1, the torque output to the front wheels 2 increases, and when it reaches a torque that allows the front wheels 2 to climb up the step f (timing t2), the front wheels 2 climb up the step f, and a vehicle speed greater than zero is generated. When the front wheels 2 climb up the step f, the torque of the front wheels 2 is reduced to prevent the vehicle 1 from suddenly accelerating, allowing the vehicle 1 to move forward gently (period T2). Then, as the rear wheels 3 approach the step f, the vehicle speed drops again to almost zero (timing t3). Then, during the subsequent period T3, the torque output to the front wheels 2 increases, and when it reaches a torque that allows the rear wheels 3 to climb up the step f (timing t4), the rear wheels 3 climb up the step f, and a vehicle speed greater than zero is generated. When the rear wheels 3 climb up the step f, the torque of the front wheels 2 is reduced so that the vehicle 1 does not suddenly accelerate, allowing the vehicle 1 to move forward slowly.

[0025] During the ideal operation of the vehicle 1 described above, the front suspension 4 may expand and contract between the time the front wheel 2 approaches the step f and the time it climbs over the step f. However, during the period T2 when the front wheel 2 climbs over the step f and the rear wheel 3 has not yet approached the step f, the vehicle body H assumes a rearward tilting posture. Therefore, the front-to-rear ratio supporting the center of gravity of the vehicle body H changes, and the rear suspension 5 compresses (the rear expansion / contraction amount becomes a negative value) and the front suspension 4 expands (the front expansion / contraction amount becomes a positive value). In other words, the difference between the front expansion / contraction amount and the rear expansion / contraction amount becomes large.

[0026] After that, when the rear wheel 3 climbs over the step f and the posture of the vehicle body H returns to horizontal, the front suspension 4 and the rear suspension 5 return to their reference extension / contraction amounts (the extension / contraction amounts when traveling at a constant speed on flat ground). In other words, the absolute value of the front extension / contraction amount becomes a value close to the reference extension / contraction amount (zero), and the absolute value of the rear extension / contraction amount becomes a value close to the reference extension / contraction amount (zero).

[0027] If the driver were to try to achieve the above-described ideal behavior of the vehicle 1 through accelerator operation, skillful manipulation would be required, which would be difficult for an inexperienced driver.

[0028] <Assist processing> When the vehicle 1 approaches a step f, the control unit 21 performs the assist process as follows. First, as shown in FIG. 2, the control unit 21 determines whether the conditions are met: the accelerator operation amount is greater than the operation amount threshold THac (for example, approximately zero), the vehicle speed is a value indicating stagnation (for example, approximately zero), and the assist operation unit 142 is in an ON position. If the conditions are met, the control unit 21 starts the assist process (timing t1). The operation amount threshold THac is not limited to approximately zero, but may be a value greater than zero that can identify that the driver intends to move forward or backward. The value indicating stagnation is not limited to approximately zero, but may include a value when the vehicle 1 vibrates slightly forward and backward. In the conditions for starting the assist process, a state in which the accelerator operation amount is greater than the operation amount threshold THac and the vehicle speed is a value indicating stagnation corresponds to a state in which the movement of the vehicle 1 according to the accelerator operation amount is stagnant.

[0029] When the assist process is started, as shown in period T1 in Fig. 2, the control unit 21 executes a torque increase process that gradually increases the torque of the electric motor 11, regardless of the rate of increase in the accelerator operation amount. As the torque gradually increases, the front wheels 2 climb over the step f, and the vehicle speed increases. The control unit 21 monitors the estimated vehicle speed, and when the vehicle speed exceeds the vehicle speed threshold THv, as shown in period T2 in Fig. 2, executes a torque reduction process that temporarily reduces the torque of the electric motor 11. The vehicle speed threshold THv is set to a value that allows for distinguishing between a state in which the vehicle 1 is stagnating and a state in which the vehicle 1 has passed the step f and is no longer stagnant.

[0030] The torque increase process during the period T1 described above allows the front wheels 2 to be gently raised onto the step f, and the torque reduction process during the period T2 described above allows the vehicle 1 to move forward gently without sudden acceleration after the front wheels 2 have climbed onto the step f.

[0031] During the assist process, the control unit 21 monitors the amount of extension and contraction of the front suspension 4 (front extension and contraction amount) and the amount of extension and contraction of the rear suspension 5 (rear extension and contraction amount). The item "suspension extension and contraction amount" in Figure 2 shows the relative extension and contraction amount when the reference extension and contraction amount is set to zero. As mentioned above, the reference extension and contraction amount means the absolute extension and contraction amount when the vehicle is traveling at a constant speed on flat ground (or when stopped).

[0032] Here, when the front extension / retraction amount becomes a positive value and the rear extension / retraction amount becomes a negative value, and the difference between the two becomes large, it can be determined that the front wheel 2 has climbed up onto a step f and the vehicle body H has become tilted backward. Therefore, the control unit 21 determines whether the difference between the front extension / retraction amount and the rear extension / retraction amount is equal to or greater than the difference threshold THfr, and if so, it determines that the front wheel 2 has climbed up onto the step f. The difference threshold THfr is set to a value that can distinguish between when the vehicle body H has become tilted backward due to the step f and when it is level.

[0033] After the torque reduction process in the period T2, the rear wheel 3 approaches the step f, and the vehicle speed again becomes a value indicating stagnation (timing t3). Therefore, when the control unit 21 determines that the vehicle is stagnating, it executes the second torque increase process (shown in the period T3). That is, the torque of the electric motor 11 is gradually increased regardless of the rate of increase in the accelerator operation amount. As the torque gradually increases, the rear wheel 3 climbs over the step f.

[0034] After the difference between the front and rear extension / contraction amounts becomes equal to or greater than the difference threshold THfr, the control unit 21 monitors whether the absolute value of the front extension / contraction amount becomes less than the first threshold THf and whether the absolute value of the rear extension / contraction amount becomes less than the second threshold THr. Here, the first threshold THf may be set to a value that can distinguish between a state in which the rear wheel 3 is not on a step f and a state in which it has been on the step f, and may be set to a value close to the reference extension / contraction amount (zero), for example. Similarly, the second threshold THr may be set to a value that can distinguish between a state in which the rear wheel 3 is not on a step f and a state in which it has been on the step f, and may be set to a value close to the reference extension / contraction amount (zero), for example.

[0035] Then, when the rear wheel 3 climbs over the step f, and the absolute value of the front extension / retraction amount becomes less than the first threshold value THf, and the absolute value of the rear extension / retraction amount becomes less than the second threshold value THr (timing t4), the control unit 21 performs an assist end process. That is, the control unit performs a torque reduction process (shown in period T4) to reduce the torque of the electric motor 11, and ends the assist process.

[0036] The torque increase process during the period T3 described above allows the rear wheels 3 to be gently raised up onto the step f, and the torque reduction process during the period T4 described above allows the vehicle 1 to move forward gently thereafter without sudden acceleration.

[0037] During the above-described assist processing, the control unit 21 monitors the operation state of the assist operating unit 142, and terminates the assist processing midway if the on operation of the assist operating unit 142 is released. This type of control allows the driver to stop the vehicle 1 from climbing up the step f midway. Alternatively, the driver can operate the vehicle 1 by operating the accelerator from midway through the climb. Furthermore, the control unit 21 may monitor a signal indicating the accelerator operation amount during the assist processing, and terminate the assist control midway if the accelerator operation amount becomes zero. This type of control allows the driver to stop the vehicle 1 from climbing up the step f midway by operating the accelerator.

[0038] <Assist control processing flow> Fig. 3 is a flowchart showing the assist control process executed by the control unit. The above-described assist process is realized by the assist control process of Fig. 3. The assist control process starts when the system of the vehicle 1 is started.

[0039] When the assist control process is started, first, the control unit 21 determines whether the accelerator operation amount is greater than the operation amount threshold THac (step S1), determines whether the estimated vehicle speed is a value indicating stagnation (for example, approximately zero) (step S2), and determines whether the assist operation unit 142 is operated to ON (step S3). If any of the above is NO, the control unit 21 repeats the determination process from step S1. On the other hand, if the results of the determination processes in steps S1 to S3 are all YES, the control unit 21 performs initialization processing of the assist process (step S4), and proceeds to step S5 to start the assist process. In the initialization processing in step S4, the control unit 21 sets the control state i, which will be described later, to an initial value "i=1", and sets the expansion / contraction difference flag to an initial value "0".

[0040] 4 is a flowchart showing details of the assist process in step S5. The assist process in FIG. 4 is repeatedly executed for each control cycle by the loop process of steps S5 to S9 in FIG.

[0041] In the assist process, first, the control unit 21 determines the control state i (step S21). The control state i is set to an initial stage value at the time of initialization in step S4 of FIG. 3. If the determination in step S21 indicates that the control state i=1 (initial stage), the control unit 21 gradually increases the torque of the electric motor 11 (step S22) and determines whether the estimated vehicle speed is equal to or greater than the vehicle speed threshold value THv (step S23). If the determination in step S23 is NO, the control unit 21 ends the process for one control cycle. On the other hand, if the determination in step S23 is YES, the control unit 21 updates the control state i to a second stage value "i=2" (step S24) and ends the process for one control cycle. In the loop process of steps S5 to S9 of FIG. 3, the process for the control state i=1 is repeatedly executed, thereby realizing the torque increase process for the period T1 of FIG. 2.

[0042] Furthermore, if the determination result in step S21 is that the control state i=2 (second stage), the control unit 21 reduces the torque of the electric motor 11 to a low value (step S25), and determines whether the vehicle speed reaches a value indicating stagnation (step S26). If the determination result in step S26 is NO, the control unit 21 ends the processing for one control cycle. On the other hand, if the determination result in step S25 is YES, the control unit 21 updates the control state i to i=3 (third stage) (step S27), and ends the processing for one control cycle. In the loop processing of steps S5 to S9 in FIG. 3, the processing for the control state i=2 is repeatedly executed, thereby realizing the torque reduction processing for the period T2 in FIG. 2.

[0043] Furthermore, if the determination result in step S21 is that the control state is i=3 (third stage), the control unit 21 gradually increases the torque of the electric motor 11 (step S28) and ends the processing of one control cycle. In the loop processing of steps S5 to S9 in Fig. 3, the processing for the control state i=3 is repeatedly executed, thereby realizing the torque increase processing for the period T3 in Fig. 2.

[0044] After executing the assist process for one control cycle in step S5 of Fig. 3, the control unit 21 subsequently determines whether the ON operation of the assist operating unit 142 is maintained (step S6). If the ON operation is maintained, the control unit 21 further determines whether the difference between the front extension / contraction amount and the rear extension / contraction amount is equal to or greater than the difference threshold value THfr (step S7). As a result, if the answer is YES, the control unit 21 sets the extension / contraction difference flag to "1" and proceeds to step S9, but if the answer is NO, the process proceeds to step S9 as is. The extension / contraction difference flag corresponds to a flag indicating that the vehicle body H has been in a rearward tilted posture and the front wheels 2 have climbed over a step f from the latter half of period T1 to the first half of period T3 in Fig. 2.

[0045] Next, the control unit 21 determines whether the extension / contraction difference flag is "1," the absolute value of the front extension / contraction amount is less than the first threshold value THf, and the absolute value of the rear extension / contraction amount is less than the second threshold value THr (step S9). If the determination result is NO, the control unit 21 returns the process to step S5. On the other hand, if the determination result of step S6 is NO or the determination result of step S9 is YES, the control unit 21 leaves the loop process of steps S5 to S9 and performs assist termination process to reduce the torque of the electric motor 11 to a low value (step S10). The process of step S10 realizes the torque reduction process for the period T4 in FIG. 2. Then, when the loop process of steps S5 to S9 ends, the assist process ends, and the control unit 21 returns the process to step S1.

[0046] 3, in the loop processing of steps S5 to S7, the control unit 21 may determine whether the accelerator operation amount is zero (step S6a), and if it is not zero, may continue the loop processing of steps S5 to S9. Furthermore, if it is zero, the control unit 21 may end the loop processing and move the processing to step S10. By adding such processing, it is possible to stop the assist processing if the accelerator operation amount becomes zero during the assist processing.

[0047] The assist control processing program is stored in a non-transitory computer readable medium such as a ROM of the control unit 21. The control unit 21 may be configured to read and execute the program stored in a portable non-transitory recording medium. The portable non-transitory recording medium may store the assist control processing program described above.

[0048] As described above, according to the vehicle control device 100 of this embodiment, the control unit 21 executes the assist process when the accelerator operation amount is greater than the operation amount threshold THac and the estimated vehicle speed is a value indicating stagnation. The assist process includes a torque increase process that gradually increases the torque of the electric motor 11 regardless of the rate of increase in the accelerator operation amount. Therefore, the assist process allows the vehicle 1 to climb up the step f without requiring difficult driving operations.

[0049] Furthermore, the control unit 21 terminates the assist control based on the detection results of the front detection unit 22, which detects the amount of expansion and contraction of the front suspension 4, and the rear detection unit 23, which detects the amount of expansion and contraction of the rear suspension 5. When the front wheels 2 are climbing up the step f, there is a characteristic difference in the amount of expansion and contraction of the front suspension 4 and the rear suspension 5 when the front wheels 2 and the rear wheels 3 are climbing up the step f. Therefore, by terminating the assist process based on these detection results, it is possible to prevent inconveniences such as the assist process terminating before the vehicle 1 climbs up the step f, and to achieve stable assist process. For example, in a configuration in which the assist control is terminated based on the estimated vehicle speed, if the front wheels 2 or the rear wheels 3 spin, the estimated vehicle speed value may increase, potentially causing the assist process to terminate before the vehicle 1 climbs up the step f. The vehicle control device 100 of this embodiment can reduce such failures.

[0050] Furthermore, according to the vehicle control device 100 of this embodiment, the control unit 21 determines whether the absolute value of the front extension / retraction amount is less than the first threshold value THf and the absolute value of the rear extension / retraction amount is less than the second threshold value THr (step S9 in FIG. 3). Then, based on the result of this determination being YES, the control unit 21 ends the assist process. Through the above determination process, the control unit 21 can more stably determine the timing when the vehicle 1 climbs up the step f. Therefore, through the assist process, the control unit 21 can end the assist process at an appropriate timing after the vehicle 1 climbs up the step f.

[0051] Furthermore, the vehicle control device 100 of this embodiment is provided with an assist operation unit 142 that can be turned on by the driver, and the control unit 21 can execute the assist process when the assist operation unit 142 is turned on. Therefore, the driver can switch between executing and not executing the assist process by operating the assist operation unit 142, and it is possible to prevent the assist process from being executed against the driver's intention.

[0052] Furthermore, according to the vehicle control device 100 of this embodiment, the assist process executed by the control unit 21 includes multiple torque increase processes (shown in periods T1 and T3 in FIG. 2). Therefore, the torque increase process when the front wheels 2 climb over a step f and the torque increase process when the rear wheels 3 climb over a step f can be performed separately. Therefore, it is also possible to perform separate torque control between the two torque increase processes.

[0053] Furthermore, according to the vehicle control device 100 of this embodiment, the control unit 21 performs a torque reduction process to reduce torque when the estimated vehicle speed exceeds the vehicle speed threshold THv during the first torque increase process (period T2 in FIG. 2). Therefore, by reducing the torque during the period from when the front wheels 2 climb up onto the step f until the rear wheels 3 approach the step f, it is possible to prevent the vehicle 1 from suddenly accelerating.

[0054] The above describes an embodiment of the present invention. However, the present invention is not limited to the above embodiment. For example, the above embodiment specifically describes an example of the conditions for terminating the assist process based on the amount of extension / compression of the front suspension 4 and the amount of extension / compression of the rear suspension 5. However, from the above conditions, for example, the condition in step S7 that the difference between the amount of extension / compression of the front suspension 4 and the amount of extension / compression of the rear suspension becomes large temporarily may be omitted, or a condition that takes into account the effect on the amount of extension / compression of the front suspension and the rear suspension based on vehicle acceleration / deceleration may be added. Also, in the above embodiment, the control unit 21 treats the amount of extension / compression of the front suspension 4 and the amount of extension / compression of the rear suspension 5 as relative values ​​when the reference amount of extension / compression is set to zero. However, the control unit 21 may treat the amount of extension / compression of the front suspension 4 and the amount of extension / compression of the rear suspension 5 as values ​​output by the front detection unit 22 and the rear detection unit 23, respectively. In this case, the control unit 21 may perform a determination process equivalent to step S9 of FIG. 3 using the values ​​output by the front detection unit 22 and the rear detection unit 23 and the retained reference amount of extension / compression of the front suspension 4 and the reference amount of extension / compression of the rear suspension 5. Furthermore, while the above embodiment illustrates a configuration for assisting the vehicle 1 to climb a step while moving forward, the present invention is also applicable to a configuration for assisting the vehicle 1 to climb a step while moving backward. In the description of the embodiment, the front wheels 2 and rear wheels 3 are reversed, and the amount of extension and contraction of the front suspension 4 and the amount of extension and contraction of the rear suspension 3 are reversed, thereby enabling the assist process when the vehicle 1 moves backward and climbs a step. Furthermore, in the above embodiment, an example was shown in which the control unit 21 performs a process for reducing torque when terminating the assist process, but this process may be omitted. Furthermore, in the above embodiment, linear sensors were used as the front detection unit that detects the amount of extension and contraction of the front suspension and the rear detection unit that detects the amount of extension and contraction of the rear suspension, but any sensor capable of detecting the amounts of extension and contraction may be used. Furthermore, in the above embodiment, an electric motor was used as the drive unit that outputs torque to the drive wheels, but the drive unit may also be an internal combustion engine.In addition, the method of estimating vehicle speed and the details shown in the embodiment can be modified as appropriate without departing from the spirit of the invention. [Explanation of symbols]

[0055] 1 vehicle 2 Front wheels (drive wheels) 3 rear wheels 4. Front suspension 5. Rear suspension 11 Electric motor (drive unit) 14 Driving operation unit 141a Accelerator detector 142 Assist operation unit 21 Control unit 22 Front detector 23 Rear detector 25 Wheel speed sensor 26 Inertial Sensor 100 Vehicle control device

Claims

1. A vehicle control device mounted on a vehicle including a drive unit that outputs torque to drive wheels, a front suspension, and a rear suspension, an accelerator detector that detects an accelerator operation amount; a vehicle speed estimation unit that estimates a vehicle speed; a front detection unit that detects the amount of expansion and contraction of the front suspension; a rear detection unit that detects the amount of expansion and contraction of the rear suspension; a control unit that starts an assist process including a torque increase process that increases the torque regardless of an increase rate of the accelerator operation amount when it is determined that the movement of the vehicle according to the accelerator operation amount is stagnating based on the vehicle speed estimated by the vehicle speed estimation unit; Equipped with The control unit based on both the detection result of the front detection unit and the detection result of the rear detection unit at the same timing, After the difference between the amount of expansion and contraction detected by the front detection unit and the amount of expansion and contraction detected by the rear detection unit exceeds a predetermined threshold, if the absolute value of the difference between the amount of expansion and contraction detected by the front detection unit and the amount of expansion and contraction of the front suspension when running at a constant speed on flat ground becomes less than a first threshold, and if the absolute value of the difference between the amount of expansion and contraction detected by the rear detection unit and the amount of expansion and contraction of the rear suspension when running at a constant speed on flat ground becomes less than a second threshold, The vehicle control device is characterized by terminating the assist processing.

2. The vehicle control device described in claim 1, characterized in that the control unit terminates the assist processing based on the absolute value of the difference between the amount of extension and contraction detected by the front detection unit and the amount of extension and contraction of the front suspension when traveling at a constant speed on flat ground being less than a first threshold value, and the absolute value of the difference between the amount of extension and contraction detected by the rear detection unit and the amount of extension and contraction of the rear suspension when traveling at a constant speed on flat ground being less than a second threshold value.

3. Further provided with an assist operation unit that can be turned on by the driver, 3. The vehicle control device according to claim 1, wherein the control unit is capable of executing the assist process when the assist operation unit is turned on.

4. 4. The vehicle control device according to claim 1, wherein the assist process includes a plurality of times of the torque increasing process.

5. 5. The vehicle control device according to claim 4, wherein the assist process includes a process of reducing the torque when the vehicle speed estimated by the first torque increase process exceeds a threshold value.

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