Vehicle control system

Abstract

To reduce a communication load between ECUs by satisfying the requirements of law and regulations related to speed meter displays according to calculation of an offset value for setting a meter-displayed vehicle speed to a value equal to or more than a detected vehicle speed and a GNSS speed, and by transmitting a gain error and the offset value from a meter display ECU to a vehicle speed control ECU in order to compute a meter-displayed vehicle speed at a vehicle speed control ECU side.SOLUTION: A vehicle control device includes a meter display ECU and a vehicle speed control ECU. The meter display ECU acquires a GNSS speed of an own vehicle, calculates a gain error of a detected vehicle speed, computes a meter-displayed vehicle speed based on the detected vehicle speed, the gain error, and an offset value, calculates an offset value so that the meter-displayed vehicle speed is a value equal to or more than the detected vehicle speed and the GNSS speed, on the basis of calculation results of gain errors in the past. The vehicle speed control ECU calculates a meter-displayed vehicle speed by using a gain error and an offset value acquired from the meter display ECU, and a detected vehicle speed acquired from a vehicle speed sensor.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Conventionally, as a technical document related to a vehicle control device, Japanese Patent No. 6400450 is known. This publication shows that the vehicle speed detected by a vehicle speed sensor of a vehicle is corrected using a GPS speed calculated based on a positioning signal of a positioning satellite.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, it is stipulated by law that the meter display vehicle speed displayed on the speedometer of the host vehicle displays a value higher than the actual vehicle speed. When the vehicle speed is corrected using the GPS speed as in the above-described conventional technology, there is a risk that the law cannot be complied with depending on the situation if only the corrected vehicle speed is displayed as the meter display vehicle speed.

Means for Solving the Problems

[0005] One aspect of the present invention is a vehicle control device having a meter display ECU that calculates the meter display speed shown on the speedometer of the vehicle and a vehicle speed control ECU that controls the vehicle speed of the vehicle, wherein the meter display ECU includes a GNSS speed acquisition unit that acquires the GNSS speed of the vehicle from the GNSS receiver of the vehicle, a gain error calculation unit that calculates the gain error of the detected vehicle speed based on the detected vehicle speed of the vehicle's vehicle speed sensor and the GNSS speed, a meter display vehicle speed calculation unit that calculates the meter display vehicle speed based on the detected vehicle speed, the gain error and the offset value, and an offset value calculation unit that calculates the offset value based on past gain error calculation results so that the meter display vehicle speed is greater than or equal to the detected vehicle speed and the GNSS speed, and the vehicle speed control ECU includes a display vehicle speed calculation unit that calculates the meter display vehicle speed using the gain error and offset value acquired from the meter display ECU and the detected vehicle speed acquired from the vehicle speed sensor, and a vehicle speed control unit that accelerates or decelerates the vehicle so that the meter display vehicle speed becomes a preset target vehicle speed as vehicle speed control of the vehicle.

[0006] In one aspect of the present invention, the vehicle control device, when the ignition of the vehicle is turned ON, may set the maximum value of the gain error calculated during the previous run as the initial value of the gain error calculated by the gain error calculation unit, and set the maximum value of the offset value calculated during the previous run as the initial value of the offset value calculated by the offset value calculation unit. [Effects of the Invention]

[0007] According to one aspect of the present invention, the requirements of regulations concerning speedometer display are met by calculating an offset value such that the meter-displayed vehicle speed is greater than or equal to the detected vehicle speed and GNSS speed. Furthermore, the communication load between ECUs can be reduced by transmitting the gain error and offset value from the meter display ECU to the vehicle speed control ECU, which then calculates the meter-displayed vehicle speed. [Brief explanation of the drawing]

[0008] [Figure 1] A block diagram showing a vehicle control device according to one embodiment. [Figure 2] This graph illustrates the detected vehicle speed, GNSS speed, gain error corrected vehicle speed, and meter-displayed vehicle speed. [Figure 3] This flowchart shows an example of the meter display vehicle speed calculation process performed by the meter display ECU. [Figure 4] This flowchart shows an example of vehicle speed control processing by the vehicle speed control ECU. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings.

[0010] The vehicle control device 100 shown in Figure 1 is a device mounted on the vehicle that calculates the vehicle speed displayed on the meter and performs vehicle speed control. The vehicle control device 100 comprises a meter display ECU [Electronic Control Unit] 10 that calculates the vehicle speed displayed on the meter and a vehicle speed control ECU [Electronic Control Unit] 20 that performs vehicle speed control.

[0011] First, let's explain the meter display ECU 10. The meter display ECU 10 is an electronic control unit having a CPU (Central Processing Unit) and a memory unit such as ROM (Read Only Memory) or RAM (Random Access Memory). The meter display ECU 10 implements various functions, for example, by executing a program stored in the memory unit using the CPU. The meter display ECU 10 may be composed of multiple electronic units. The configuration of the vehicle speed control ECU 20 can be similar.

[0012] As shown in Figure 1, the meter display ECU 10 is connected to the GNSS (Global Navigation Satellite System) receiver 1 and the vehicle speed sensor 2. The GNSS receiver 1 measures the vehicle's position (for example, the vehicle's latitude and longitude) by receiving a carrier wave (GNSS signal) from positioning satellites. The GNSS receiver 1 transmits the frequency information of the acquired carrier wave to the meter display ECU 10. Note that the GNSS receiver 1 may be a GPS (Global Positioning System) receiver.

[0013] The vehicle speed sensor 2 is a detector that detects the vehicle speed of the vehicle. The vehicle speed sensor is installed on, for example, the wheels of the vehicle or the drive shaft that rotates together with the wheels, and a wheel speed sensor that detects the rotational speed of the wheels is used. The vehicle speed sensor transmits the detected vehicle speed information (for example, the vehicle speed pulse signal of the wheel speed sensor) to the meter display ECU 10. The vehicle speed sensor also transmits the detected vehicle speed information to the vehicle speed control ECU 20.

[0014] Next, the functional configuration of the meter display ECU 10 will be described. The meter display ECU 10 includes a GNSS speed acquisition unit 11, a vehicle speed calculation unit 12, a meter correction coefficient calculation unit 13, and a meter display vehicle speed calculation unit 14.

[0015] The GNSS speed acquisition unit 11 acquires the GNSS speed of the vehicle based on the carrier waves of the positioning satellites (GNSS satellites) received by the GNSS receiver unit 1. GNSS speed is the speed of the vehicle calculated from the carrier waves of the positioning satellites. The GNSS speed acquisition unit 11 calculates the GNSS speed from the change in the frequency of the received carrier wave due to the Doppler effect. The GNSS speed acquisition unit 11 can calculate the GNSS speed using, for example, the carrier waves of four or more positioning satellites.

[0016] The vehicle speed calculation unit 12 calculates the detected vehicle speed of the vehicle based on the detected vehicle speed information from the vehicle speed sensor 2. The vehicle speed calculation unit 12 can determine the detected vehicle speed from, for example, a vehicle speed pulse signal.

[0017] The meter correction coefficient calculation unit 13 calculates a meter correction coefficient for calculating the meter display vehicle speed. The meter correction coefficient includes a gain error and an offset value. As shown in FIG. 1, the meter correction coefficient calculation unit 13 has a gain error calculation unit 31 and an offset value calculation unit 32.

[0018] The gain error calculation unit 31 calculates the gain error of the detected vehicle speed based on the detected vehicle speed of the host vehicle and the GNSS speed. The gain error is a coefficient used for calculating the meter display vehicle speed. The detected vehicle speed has an error due to changes in the tire diameter or distortion of the drive shaft due to the running of the host vehicle. Therefore, a gain error for correcting the detected vehicle speed using the highly accurate GNSS speed is calculated.

[0019] An example of the gain error can be obtained from the equation GNSS speed = gain error × detected vehicle speed. In this case, the gain error is the value obtained by dividing the GNSS speed by the detected vehicle speed. The gain error calculation unit 31 may be obtained by applying the least squares method to the detected vehicle speed and the GNSS speed over a certain period of time. The gain error calculation unit 31 may calculate a gain error for correcting the detected vehicle speed to approach the GNSS speed by means of a Kalman filter or other processing instead of the least squares method.

[0020] [[ID=eleven]] The offset value calculation unit 32 calculates an offset value based on the calculation result of the past gain error. The offset value is a coefficient used for calculating the meter display vehicle speed. Details of the calculation of the offset value will be described later.

[0021] The meter display vehicle speed calculation unit 14 calculates the meter display vehicle speed based on the detected vehicle speed, the gain error, and the offset value. Specifically, the meter display vehicle speed calculation unit 14 calculates the meter display vehicle speed by adding the offset value to the gain error corrected vehicle speed obtained by multiplying the detected vehicle speed by the gain error. That is, the meter display vehicle speed calculation unit 14 can obtain the meter display vehicle speed as meter display vehicle speed = gain error × detected vehicle speed + offset value.

[0022] Here, FIG. 2 is a graph for explaining the detected vehicle speed, GNSS speed, gain error corrected vehicle speed, and meter display vehicle speed. The vertical axis of the graph in FIG. 2 is the vehicle speed, and the horizontal axis is the time. FIG. 2 shows the detected vehicle speed, GNSS speed, gain error corrected vehicle speed, and meter display vehicle speed. In FIG. 2, a situation where the detected vehicle speed is smaller than the GNSS speed is shown as an example. In the situation shown in FIG. 2, as indicated by arrow A, the gain error corrected vehicle speed is obtained by multiplying the detected vehicle speed by the gain error. The gain error corrected vehicle speed is the vehicle speed corrected so as to approach the GNSS speed from the detected vehicle speed.

[0023] The gain error corrected vehicle speed in FIG. 2 is lower than the GNSS speed. If the gain error corrected vehicle speed is directly used as the meter display vehicle speed, there is a possibility that the requirements of the regulations regarding the display of the speedometer may not be met. The requirements of the regulations regarding the display of the speedometer are the requirements that the meter display vehicle speed displayed on the speedometer of the own vehicle be a value greater than or equal to the actual vehicle speed. Therefore, the meter display vehicle speed calculation unit 14 calculates the meter display vehicle speed as a value greater than or equal to the detected vehicle speed and the GNSS speed by adding an offset value to the gain error corrected vehicle speed as indicated by arrow B.

[0024] The offset value is set so as to meet the requirements of the regulations regarding the display of the speedometer. The offset value calculation unit 32 calculates the offset value so that the meter display vehicle speed is a value greater than or equal to the detected vehicle speed and the GNSS speed, taking into account the variation in the calculation result of the gain error. The offset value calculation unit 32 calculates the offset value so that the meter display vehicle speed is a value greater than or equal to the detected vehicle speed and the GNSS speed even when the gain error is at the minimum value. The offset value calculation unit 32 may be obtained as a value obtained by adding a fixed value to the difference between the larger value of the detected vehicle speed or the GNSS speed and the gain error corrected vehicle speed when the gain error is at the minimum value.

[0025] The meter display speed calculation unit 14 can determine a meter display speed that is equal to or greater than the detected vehicle speed and GNSS speed by adding the offset value calculated as described above to the gain error corrected vehicle speed. The meter display speed calculation unit 14 outputs the meter display speed to another part. For example, the meter display speed calculation unit 14 outputs a signal corresponding to the meter display speed to the vehicle's speedometer. The meter display speed calculation unit 14 transmits the gain error and offset value used in calculating the meter display speed to the vehicle speed control ECU 20.

[0026] The meter display ECU 10 may set the maximum gain error calculated during the previous run as the initial value of the gain error calculated by the gain error calculation unit 31 when the vehicle's ignition is turned ON. Similarly, the meter display ECU 10 may set the maximum offset value calculated during the previous run as the initial value of the offset value calculated by the offset value calculation unit 32 when the vehicle's ignition is turned ON.

[0027] The meter display ECU 10 may calculate the gain error and offset value so as not to exceed the initial value. Furthermore, the initial value of the offset may be predetermined based on the assumption that the vehicle is fitted with the largest possible diameter tire. In this way, the meter display ECU 10 can meet the regulatory requirements for speedometers even if the tire diameter is changed while the ignition is off.

[0028] Next, the vehicle speed control ECU 20 will be described. As shown in Figure 1, the vehicle speed control ECU 20 is connected to the vehicle speed sensor 2 and the target vehicle speed setting unit 3.

[0029] The target vehicle speed setting unit 3 sets the target vehicle speed used for vehicle speed control. For example, the target vehicle speed setting unit 3 sets the target vehicle speed for cruise control as a driving assistance function based on user operation. The target vehicle speed setting unit 3 may also set the target vehicle speed for speed management, which is deceleration assistance before a curve, based on user operation. The target vehicle speed setting unit 3 may also set the target vehicle speed for other driving assistance functions based on user operation. The target vehicle speed setting unit 3 may also set the target vehicle speed for automatic driving control. In this case, the target vehicle speed setting unit 3 may constitute part of the driving plan generation function in automatic driving control.

[0030] The vehicle speed control ECU 20 includes a display vehicle speed calculation unit 21 and a vehicle speed control unit 22. The display vehicle speed calculation unit 21 calculates the meter display vehicle speed based on the gain error and offset value transmitted from the meter display ECU 10 and the detected vehicle speed obtained from the vehicle speed sensor 2. The method for calculating the meter display vehicle speed is the same as that of the meter display ECU 10.

[0031] The vehicle speed control unit 22 performs vehicle speed control by accelerating or decelerating the vehicle so that the meter-displayed vehicle speed calculated by the display vehicle speed calculation unit 21 becomes the target vehicle speed set by the target vehicle speed setting unit 3. Vehicle speed control may be a driving assistance such as cruise control, or it may be part of an automatic driving control. For example, the vehicle speed control unit 22 calculates a target driving force or target deceleration force so that the meter-displayed vehicle speed becomes the target vehicle speed.

[0032] The vehicle speed control unit 22 accelerates the vehicle by transmitting a signal corresponding to the target driving force to the vehicle's drive actuator. The drive actuator is, for example, a throttle actuator. The drive actuator may also be a motor in a hybrid vehicle or an electric vehicle. The vehicle speed control unit 22 decelerates the vehicle by transmitting a signal corresponding to the target deceleration force to the vehicle's brake actuator. The vehicle speed control unit 22 may control the acceleration or deceleration of the vehicle by other well-known methods.

[0033] Next, the processing of the vehicle control device 100 according to this embodiment will be described with reference to the drawings. Figure 3 is a flowchart showing an example of the meter display vehicle speed calculation process by the meter display ECU. The meter display vehicle speed calculation process is performed, for example, while the vehicle's ignition is ON.

[0034] As shown in Figure 3, the meter display ECU 10 of the vehicle control device 100 acquires the GNSS speed of its own vehicle as S1 using the GNSS speed acquisition unit 11. The GNSS speed acquisition unit 11 acquires the GNSS speed based on the carrier waves of the positioning satellites received by the GNSS receiver unit 1.

[0035] In S2, the meter display ECU 10 calculates the vehicle speed detected by the vehicle speed calculation unit 12. The vehicle speed calculation unit 12 calculates the vehicle speed detected by the vehicle speed sensor 2 based on the vehicle speed information detected by the vehicle speed sensor 2.

[0036] In S3, the meter display ECU 10 determines whether the vehicle has just had its ignition turned ON. If the meter display ECU 10 determines that the vehicle has just had its ignition turned ON, it proceeds to S4. If the meter display ECU 10 determines that the vehicle has not just had its ignition turned ON, it proceeds to S5.

[0037] In S4, the meter display ECU 10 sets an initial value for the meter correction coefficient using the meter correction coefficient calculation unit 13. The meter correction coefficient calculation unit 13 sets, for example, the maximum value of the gain error calculated during the previous run as the initial value of the gain error calculated by the gain error calculation unit 31. Similarly, the meter correction coefficient calculation unit 13 sets the maximum value of the offset value calculated during the previous run as the initial value of the offset value calculated by the offset value calculation unit 32. After that, the meter display ECU 10 moves to S6.

[0038] In S5, the meter display ECU 10 calculates the meter correction coefficient using the meter correction coefficient calculation unit 13. The gain error calculation unit 31 of the meter correction coefficient calculation unit 13 calculates the gain error of the detected vehicle speed based on the detected vehicle speed and GNSS speed of the vehicle. The offset value calculation unit 32 of the meter correction coefficient calculation unit 13 calculates an offset value based on the past gain error calculation results so that the meter display vehicle speed is greater than or equal to the detected vehicle speed and GNSS speed. After that, the meter display ECU 10 moves to S6.

[0039] In S6, the meter display ECU 10 calculates and outputs the meter display vehicle speed using the meter display vehicle speed calculation unit 14. The meter display vehicle speed calculation unit 14 calculates the meter display vehicle speed by adding an offset value to the gain error corrected vehicle speed, which is obtained by multiplying the detected vehicle speed by the gain error. The meter display vehicle speed calculation unit 14 outputs a signal corresponding to the meter display vehicle speed to, for example, the vehicle's speedometer.

[0040] In S7, the meter display ECU 10 transmits the meter correction coefficient to the vehicle speed control ECU 20. After that, the meter display ECU 10 finishes the current meter display vehicle speed calculation process. The meter display ECU 10 repeats the process from S1 again after a certain period of time.

[0041] Figure 4 is a flowchart illustrating an example of vehicle speed control processing by the vehicle speed control ECU 20. As shown in Figure 4, the vehicle speed control ECU 20 obtains the target vehicle speed from the target vehicle speed setting unit 3 as S10. The target vehicle speed setting unit 3 sets the target vehicle speed for cruise control as a driving assistance function, for example, based on user operation.

[0042] In S11, the vehicle speed control ECU 20 acquires the vehicle's detected speed using the display vehicle speed calculation unit 21. The display vehicle speed calculation unit 21 acquires the vehicle's detected speed from the vehicle speed sensor 2.

[0043] In S12, the vehicle speed control ECU 20 receives a meter correction coefficient from the meter display ECU 10. The display vehicle speed calculation unit 21 recognizes the gain error and offset value received from the meter display ECU 10.

[0044] In S13, the vehicle speed control ECU 20 calculates the meter-displayed vehicle speed using the display vehicle speed calculation unit 21. The display vehicle speed calculation unit 21 calculates the meter-displayed vehicle speed based on the gain error and offset value transmitted from the meter display ECU 10 and the detected vehicle speed obtained from the vehicle speed sensor 2.

[0045] In S14, the vehicle speed control ECU 20 calculates a target driving force or target deceleration force to achieve the target vehicle speed using the vehicle speed control unit 22. For example, the vehicle speed control unit 22 calculates a target driving force or target deceleration force so that the meter-displayed vehicle speed becomes the target vehicle speed.

[0046] As described above, the vehicle control device 100 according to this embodiment can obtain highly accurate speed information by correcting the detected vehicle speed using the GNSS speed. Furthermore, the vehicle control device 100 can satisfy the requirements of regulations regarding speedometer display by calculating an offset value such that the meter-displayed vehicle speed is greater than or equal to the detected vehicle speed and the GNSS speed. Moreover, the vehicle control device 100 can reduce the communication load between ECUs by transmitting the gain error and offset value from the meter display ECU 10 to the vehicle speed control ECU 20 and calculating the meter-displayed vehicle speed on the vehicle speed control ECU 20 side.

[0047] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above. The present invention can be implemented in various forms, starting with the embodiments described above, by making various changes and improvements based on the knowledge of those skilled in the art.

[0048] For example, the GNSS speed acquisition unit 11 does not necessarily need to acquire GNSS speed using the Doppler effect; it may determine the position of the vehicle from the carrier wave of the positioning satellite received by the GNSS receiver unit 1 and calculate the GNSS speed from the change in the vehicle's position per unit time.

[0049] The initial values ​​of the gain error and offset are not limited to the maximum values ​​from the previous run. The initial values ​​may be fixed values ​​or user-defined values. [Explanation of symbols]

[0050] 1...GNSS receiver unit, 2...vehicle speed sensor, 10...meter display ECU, 11...GNSS speed acquisition unit, 14...meter display vehicle speed calculation unit, 12...vehicle speed calculation unit, 13...meter correction coefficient calculation unit, 20...vehicle speed control ECU, 21...display vehicle speed calculation unit, 22...vehicle speed control unit, 31...gain error calculation unit, 32...offset value calculation unit, 100...vehicle control device.

Claims

1. A vehicle control device having a meter display ECU that calculates the meter display vehicle speed shown on the vehicle's speedometer and a vehicle speed control ECU that controls the vehicle speed of the vehicle, The aforementioned meter display ECU is A GNSS speed acquisition unit that acquires the GNSS speed of the vehicle from the GNSS receiving unit of the vehicle, A gain error calculation unit calculates the gain error of the detected vehicle speed based on the vehicle speed sensor of the vehicle and the GNSS speed, A meter display vehicle speed calculation unit calculates the meter display vehicle speed based on the detected vehicle speed, the gain error, and the offset value, An offset value calculation unit calculates the offset value based on the past gain error calculation results so that the meter-displayed vehicle speed is greater than or equal to the detected vehicle speed and the GNSS speed, Equipped with, The aforementioned vehicle speed control ECU is A display vehicle speed calculation unit calculates the meter display vehicle speed using the gain error and offset value obtained from the meter display ECU and the detected vehicle speed obtained from the vehicle speed sensor. A vehicle control device comprising a vehicle speed control unit that accelerates or decelerates the vehicle so that the meter-displayed vehicle speed becomes a preset target vehicle speed, as a vehicle speed control of the vehicle.

2. The vehicle control device according to claim 1, wherein the meter display ECU sets the maximum value of the gain error calculated during the previous run as the initial value of the gain error calculated by the gain error calculation unit when the ignition of the vehicle is turned ON, and sets the maximum value of the offset value calculated during the previous run as the initial value of the offset value calculated by the offset value calculation unit.

3. The vehicle control device according to claim 1 or 2, wherein the GNSS speed acquisition unit acquires the GNSS speed from the change in the frequency of the carrier wave from the positioning satellite.

Images