Control device, control method, and control program

Abstract

To provide a control device that enables the stability of control to be improved when deceleration control by an operation support system ends.SOLUTION: A control device is provide, acquiring required acceleration from an operation support system and controlling a power train and a brake on the basis of the acquired required acceleration, the control device includes: an acquisition unit acquiring the required acceleration and end information that represents the end of deceleration control; and a control unit inhibiting the power train from generating drive power larger than a lower limit torque that is a lower limit value of torque that can be presently output from the power train in a case where the acquisition unit acquires the end information.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a control device mounted on a vehicle or the like. [Background technology]

[0002] In recent years, vehicles have been equipped with various driving assistance systems. In addition, a control device has been proposed that controls the powertrain and brakes by arbitrating requests from such driving assistance systems and requests from the user (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-120352 A Summary of the Invention [Problem to be solved by the invention]

[0004] When the driving assistance system terminates the driving assistance function during deceleration control that operates the vehicle brakes, in order to suppress discomfort to the user caused by suddenly stopping deceleration, the driving assistance system executes degeneration control that gradually reduces the braking force by the deceleration control as a termination process. The degeneration control is terminated, for example, when a state is realized in which no braking force is generated in the brakes, no unnecessary output torque is generated in the powertrain, and a lower limit torque that is the lower limit of the range of torque that can currently be output is output.

[0005] The ECU equipped with the driving assistance system obtains the lower limit of the torque that can currently be output from the ECU that controls the powertrain via the in-vehicle network, and performs feedback control based on this to perform the above-mentioned degeneration control. This lower limit changes depending on the current state of the powertrain. Therefore, if a delay occurs in the degeneration control due to a communication delay in the in-vehicle network, it may not be possible to keep up with the change in the lower limit, which may result in unstable control of the driving force and braking force.

[0006] The present invention has been made in consideration of the above-mentioned problems, and has an object to provide a control device etc. that improves the stability of control at the time of terminating deceleration control by a driving assistance system. [Means for solving the problem]

[0007] In order to solve the above problem, one aspect of the present invention is a control device that acquires a required acceleration from a driving assistance system and controls a powertrain and brakes based on the acquired required acceleration, the control device comprising: an acquisition unit that acquires from the driving assistance system end information indicating the end of the required acceleration and deceleration control; and a control unit that, when the acquisition unit acquires the end information, prohibits the powertrain from generating a driving force greater than a lower limit torque, which is the lower limit value of the torque that the powertrain can currently output. Effect of the Invention

[0008] According to the present invention, the control device acquires end information indicating the end of deceleration control by the driving assistance system and uses this as a trigger to perform a predetermined process, thereby making it possible to improve the stability of control. [Brief description of the drawings]

[0009] [Figure 1] A configuration diagram of a control device and its peripheral parts according to an embodiment of the present invention. [Diagram 2] 1 is a flowchart showing a process according to an embodiment of the present invention. [Diagram 3] Graph showing an example of a process according to an embodiment of the present invention. [Figure 4] Graph showing an example of processing according to a comparative example DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (Embodiment) Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the control device according to this embodiment, when the driving assistance system is performing degeneration control, which is a process for terminating the deceleration control, the control device detects this and prevents the power train from generating an output torque greater than the lower limit torque regardless of the acceleration required by the driving assistance system. This allows the degeneration control to be terminated early, thereby improving the stability of the vehicle control.

[0011] <Configuration> FIG. 1 shows a configuration diagram of a control device 10 according to this embodiment and its peripheral parts.

[0012] In this embodiment, the control device 10 is connected to a powertrain ECU 20 and a brake ECU 30 via a network. In addition, various ECUs (electronic control units), such as a camera ECU 41, an automatic driving ECU 42, and a clearance sonar ECU 43, are connected to the control device 10 via a network. The powertrain ECU 20 is an ECU that controls an engine and a transmission (or a motor) equipped in the vehicle. The brake ECU 30 is an ECU that controls a brake equipped in the vehicle. The control device 10 includes an acquisition unit 12 that acquires information from these ECUs, and a control unit 11 that controls the powertrain ECU 20 and the brake ECU 30 based on the acquired information, and can control the driving force and the braking force.

[0013] Hereinafter, when referring to driving force and braking force, they are both expressed as absolute values. When driving force and braking force are collectively referred to as braking / driving force, they are expressed as signed values ​​with positive values ​​acting in the vehicle's traveling direction. When referring to acceleration, they are expressed as signed values ​​with positive values ​​acting in the vehicle's traveling direction.

[0014] The control device 10 and each ECU are typically computers each including a control unit, which is a processor, and a memory, etc. The functions of the control device 10 may be implemented in an independently provided device such as an ECU, or may instead be implemented by being integrated into either the powertrain ECU 20 or the brake ECU 30, etc., or by being appropriately distributed between them.

[0015] The camera ECU 41 is an ECU that implements functions such as following the vehicle ahead and collision avoidance. The autonomous driving ECU 42 is an ECU that implements an autonomous driving function that executes all driving tasks. The clearance sonar ECU 43 is an ECU that implements functions such as collision avoidance. In this way, a vehicle is provided with a plurality of driving assistance systems, for example, by a plurality of ECUs. The control device 10 arbitrates requests from the driving assistance systems based on predetermined rules, and controls the braking / driving force based on the arbitration result.

[0016] <Processing> The degeneration response process performed by the control device 10 in response to the degeneration control of the driving assistance system according to this embodiment will be described below with reference to the flowchart shown in Fig. 2. In this process, it is assumed that one or more driving assistance systems provided in the vehicle are operating, and the control device 10 controls the braking / driving force based on a request from one driving assistance system selected as a result of arbitration. This process is also repeatedly executed while the driving assistance systems are operating.

[0017] (Step S101): The acquisition unit 12 of the control device 10 acquires, from the selected driving assistance system, a requested acceleration and a degenerate flag indicating whether or not degenerate control for ending deceleration control is in progress. The requested acceleration is the acceleration that the driving assistance system requests the vehicle to generate. When the degenerate flag is on, it indicates that the driving assistance system is performing a process of gradually reducing the degree of deceleration in order to end deceleration control. In other words, when the degenerate flag is on, it means that the driving assistance system is ending deceleration control.

[0018] (Step S102): The acquisition unit 12 acquires a lower limit torque, which is a lower limit value of the torque that the powertrain can currently output, from the powertrain ECU 20. Note that the powertrain ECU 20 can calculate the lower limit torque based on, for example, the current engine speed, throttle opening, and gear ratio of the transmission or torque converter in the case of an engine vehicle, or based on the current regenerative power generation rate in the case of an electric vehicle.

[0019] (Step S103): The control unit 11 of the control device 10 judges whether or not the degenerate flag is on. If the degenerate flag is on, the process proceeds to step S104, and if the degenerate flag is off, the process proceeds to step S106.

[0020] (Step S104): The control unit 11 compares the required acceleration with the lower limit torque equivalent acceleration. The lower limit torque equivalent acceleration is the acceleration generated in the vehicle by the lower limit torque, and the control unit 11 can calculate it based on the lower limit torque and the vehicle weight, etc. Note that in step S103, the acquisition unit 12 may acquire the lower limit torque equivalent acceleration from the powertrain ECU 20 instead of the lower limit torque. If the required acceleration is greater than the lower limit torque equivalent acceleration, the process proceeds to step S105, and if the required acceleration is equal to or less than the lower limit torque equivalent acceleration, the process proceeds to step S106.

[0021] (Step S105): The control unit 11 replaces the required acceleration acquired from the driving assistance system with the lower limit torque equivalent acceleration, and sets the result as the required acceleration to be used for control in the next step S106. That is, the upper limit is guarded so that the required acceleration to be used for control does not exceed the lower limit torque equivalent acceleration.

[0022] (Step S106): The control unit 11 controls the powertrain ECU 20 and the brake ECU 30 based on the required acceleration. If the required acceleration is greater than the acceleration equivalent to the lower limit torque, the control unit 11 controls the powertrain ECU 20 to generate an output torque greater than the lower limit torque in the powertrain, and controls the brake ECU 30 not to generate a braking force in the brakes, thereby generating the required acceleration in the vehicle. If the required acceleration is equal to or less than the acceleration equivalent to the lower limit torque, the control unit 11 controls the powertrain ECU 20 to generate a lower limit torque in the powertrain, and controls the brake ECU 30 to generate a braking force in the brakes, thereby generating the required acceleration in the vehicle.

[0023] During control by the driving assistance system, the above-mentioned steps S101 to S106 are repeatedly executed. Furthermore, when the control device 10 acquires a new required acceleration from another driving assistance system, the control device 10 can switch the processing to control based on a request from the other driving assistance system according to the arbitration result based on a predetermined rule.

[0024] An example of control by the above processing will be described. An example of control is shown in Fig. 3. Fig. 3 is a graph with time on the horizontal axis and acceleration, braking / driving force, and braking force on the vertical axis, and the required acceleration used by the control device 10 in the processing of step S106 described above, the braking / driving force generated in the powertrain (offset from the lower limit torque at each time), and the braking force generated in the brakes are shown by solid lines. Also, a part of the required acceleration output by the driving assistance system to the control device 10 is shown by dotted lines. The control device 10 acquires this required acceleration after a certain communication delay time has elapsed. The required acceleration is actually a discrete value calculated by the driving assistance system at regular intervals and acquired by the control device 10, but is shown continuously in Fig. 3.

[0025] The driving assistance system performs deceleration control until time T1, and at time T1, for example, determines to end the deceleration control in response to an instruction from a user.

[0026] After time T1, the driving assistance system turns on the degeneration flag, acquires the lower limit torque or the acceleration equivalent to the lower limit torque from the powertrain ECU 20, and performs degeneration control to gradually increase the required acceleration while suppressing abrupt changes by setting an upper limit on the absolute value of the jerk, for example, so that the required acceleration coincides with the acceleration equivalent to the lower limit torque. This control can be performed, for example, by feedback control that compares the required acceleration with the actual acceleration of the vehicle. If there is no communication delay, the degeneration control ends at time T3 or a relatively short time thereafter. In FIG. 3, the required acceleration indicated by the dotted line is shown up to time T3.

[0027] The control device 10 acquires the required acceleration with a delay and performs processing based on the required acceleration. After time T2, the degeneration in progress flag is turned on, and the control device 10 performs the degeneration response processing described above. After time T2, the lower limit torque tends to decrease, and at time T4, the required acceleration acquired by the control device 10 exceeds the lower limit torque equivalent acceleration. After time T4, the period up to at least time T5 is one in which the required acceleration is greater than the lower limit torque equivalent acceleration, and therefore, during this period, the control device 10 replaces the required acceleration with the lower limit torque equivalent acceleration as the degeneration response processing.

[0028] By the above process, the braking / driving force generated in the powertrain is maintained at the lower limit torque, unnecessary output torque is not generated, and the state of the powertrain is stabilized. Therefore, even if there is a delay, the degeneration control is likely to converge, and the degeneration control can be ended at time T6, for example.

[0029] In reality, the lower limit torque acquired by the control device 10 in step S103 may differ from the current lower limit torque due to a delay in acquisition caused by a communication delay. Even in this case, the lower limit torque acquired in step S103 is more recent than the lower limit torque acquired by the driving assistance system at the time of calculation of the required acceleration acquired in step S101, so that the degeneration response process can be performed reflecting the newer lower limit torque, thereby making it possible to speed up the convergence of the degeneration control.

[0030] The degeneration response process may be modified as appropriate as long as it can stabilize the degeneration control. For example, instead of replacing the required acceleration with the acceleration equivalent to the lower limit torque in step S105, the powertrain ECU 20 may be instructed to prohibit the generation of a driving force larger than the current lower limit torque regardless of the instruction in the next step S106.

[0031] As a comparative example, an example of control in the case where the control device 10 does not perform the above-mentioned degeneration handling process will be shown below. Fig. 4 shows a schematic diagram of the example of control, similar to Fig. 3 .

[0032] The driving assistance system performs deceleration control until time T1, and at time T1, for example, determines to end the deceleration control in response to an instruction from a user.

[0033] After time T1, the driving assistance system acquires the lower limit torque or the acceleration equivalent to the lower limit torque from the powertrain ECU 20, and gradually increases the required acceleration while setting an upper limit on the absolute value of the jerk, for example, to perform degeneration control with the goal of making the required acceleration equal to the acceleration equivalent to the lower limit torque. This control can be performed, for example, by feedback control that compares the required acceleration with the actual acceleration of the vehicle. If there is no communication delay, the degeneration control ends at time T3.

[0034] The control device 10 acquires the required acceleration with a delay and performs processing based on the required acceleration. Because the lower limit torque is on a decreasing trend, the required acceleration acquired by the control device 10 exceeds the acceleration equivalent to the lower limit torque at time T4. After time T4, the control device 10 does not perform the degeneration response processing described above, so that the powertrain generates a driving force larger than the lower limit torque.

[0035] In this way, the braking / driving force generated by the powertrain is not maintained at the lower limit torque, and the powertrain operates unnecessarily on the driving side, which makes it difficult for the degeneration control by the driving assistance system to converge, causing control hunting in which the driving force generated by the powertrain and the braking force generated by the brakes oscillate, and the end of the degeneration control may be delayed or may not be able to be ended.

[0036] <Effects> In the control device 10 according to this embodiment, when the driving assistance system is performing degeneration control at the end of the deceleration control, this is detected and the powertrain is prevented from generating a braking / driving force larger than the lower limit torque regardless of the requested acceleration from the driving assistance system. This makes it possible to quickly end the degeneration control and improve the stability of the vehicle control.

[0037] The control device 10 can detect that the degeneration control is in progress by a simple method of acquiring a degeneration in progress flag. Furthermore, the control device 10 imposes a minimum restriction, namely an upper limit guard, on the required acceleration calculated by each driving assistance system during degeneration control using a unique method, but does not impose any other restrictions, so that each driving assistance system can make maximum use of the degeneration control method adopted according to its characteristics.

[0038] In order to make the driving assistance system compatible with this embodiment, it is only necessary to additionally implement a feature that turns on a degenerate flag during degenerate control and notifies the control device 10. Therefore, the amount of additional programs is small, and development and memory can be saved. In addition, the amount of communication for notifying the degenerate flag is small. In recent years, a specification standard has been proposed in which the driving assistance system generates various numerical parameters related to the degenerate control in addition to the required acceleration as a process during the degenerate control and transmits them to the in-vehicle network. Compared to adopting this standard, the costs of communication, processing, memory, and development can be significantly reduced.

[0039] The present invention can be understood not only as a vehicle control device, but also as a driving assistance system including a control device and other devices, a control method executed by a control device having a processor and memory, a control program, a computer-readable non-transitory storage medium storing a control program, a vehicle equipped with a control device, etc. [Industrial Applicability]

[0040] The present invention is useful for a control device mounted on a vehicle or the like. [Explanation of symbols]

[0041] 10 Control device 11 Control section 12 Acquisition Department 20 Powertrain ECU 30 Brake ECU 41 Camera ECU 42 Autonomous Driving ECU 43 Clearance sonar ECU

Claims

1. A control device that acquires a required acceleration from a driving assistance system and controls a powertrain and a brake based on the acquired required acceleration, an acquisition unit that acquires end information representing an end of the required acceleration and deceleration control from the driving assistance system; a control unit that, when the acquisition unit acquires the termination information, prohibits the powertrain from generating a driving force greater than a lower limit torque, which is a lower limit value of a torque that the powertrain can currently output.

2. A control device that acquires a required acceleration from a driving assistance system and controls a powertrain and a brake based on the acquired required acceleration, an acquisition unit that acquires end information representing an end of the required acceleration and deceleration control from the driving assistance system, and acquires from the powertrain a lower limit torque that is a lower limit value of a torque that the powertrain can currently output; a control unit that, when the acquisition unit acquires the end information, turns on a degeneration in progress flag indicating whether or not degeneration control for terminating the deceleration control is in progress, and while the degeneration in progress flag is on, compares the requested acceleration with an acceleration determined based on the lower limit torque, and prohibits the powertrain from generating a driving force greater than the current lower limit torque based on a result of the comparison.

3. The control unit performs a degeneration control to gradually reduce the braking force as a process for terminating the deceleration control. The control device according to claim 1 or 2.

4. A control method executed by a computer of a control device that acquires a required acceleration from a driving assistance system and controls a powertrain and a brake based on the acquired required acceleration, comprising: obtaining end information indicating an end of the required acceleration and deceleration control from the driving assistance system; and when the end information is acquired, prohibiting the powertrain from generating a driving force larger than a lower limit torque, which is a lower limit value of a torque that the powertrain can currently output. Control methods.

5. A control program to be executed by a computer of a control device that acquires a required acceleration from a driving assistance system and controls a power train and a brake based on the acquired required acceleration, obtaining end information indicating an end of the required acceleration and deceleration control from the driving assistance system; and when the end information is acquired, prohibiting the powertrain from generating a driving force larger than a lower limit torque, which is a lower limit value of a torque that the powertrain can currently output. Control program.

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