Vehicle weight estimation device

Abstract

To provide a weight estimation device for a vehicle which can enhance the accuracy of estimation of vehicle weight which is to be registered.SOLUTION: A weight estimation device 100 for a vehicle 10 detects a drive force and an acceleration of the vehicle 10 in a prescribed period, detects the vehicle drive force, the acceleration and a road surface gradient in the prescribed period, estimates the weight of the vehicle 10 on the basis of the detected drive force and the acceleration. When a specific condition indicating that the accuracy of the estimation of the estimated weight of the vehicle 10 is higher than the accuracy of the estimation of the registered weight of the vehicle 10 holds, the weight estimation device changes the registered weight of the vehicle to the estimated weight of the vehicle 10 on the basis of the drive force and the acceleration of the vehicle 10 which were detected in the prescribed period.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] A vehicle weight estimation device that estimates the weight of a vehicle based on the driving force and acceleration of the vehicle is known in the art. However, in a configuration that estimates the weight of a vehicle based on the driving force and acceleration of the vehicle, if the driving force and acceleration fluctuate greatly when estimating the weight of the vehicle, the accuracy of the estimation of the weight of the vehicle may be reduced due to these fluctuations.

[0003] The vehicle weight estimation device disclosed in Patent Document 1 is configured to determine whether or not the vehicle is towing another vehicle, and when it is determined that the vehicle is towing another vehicle, not to estimate the vehicle weight until a predetermined time has passed since the determination. Furthermore, this vehicle weight estimation device is configured to estimate the vehicle weight when the driving force of the vehicle is equal to or greater than a reference driving force and the acceleration of the vehicle is equal to or greater than a reference acceleration. According to the vehicle weight estimation device of Patent Document 1, even if rattle occurs at the fastening point with the other vehicle immediately after the vehicle starts, the vehicle weight can be estimated without being affected by the fluctuation in acceleration due to the rattle. Furthermore, according to the vehicle weight estimation device of Patent Document 1, when the driving force of the vehicle is equal to or greater than a reference driving force and the acceleration of the vehicle is equal to or greater than a reference acceleration, the vehicle weight can be estimated appropriately.

[0004] However, while the vehicle weight estimation device described in Patent Document 1 can prevent the estimation of the vehicle weight from being affected by rattling immediately after the vehicle starts, if the acceleration of the vehicle fluctuates while the vehicle is traveling (i.e., after a predetermined time has elapsed since the vehicle starts), the accuracy of the estimation of the vehicle weight may decrease. Even if the driving force of the vehicle is equal to or greater than the reference driving force and the acceleration of the vehicle is equal to or greater than the reference acceleration, if the fluctuations in the driving force and acceleration of the vehicle are large, the accuracy of the estimation of the vehicle weight may decrease due to these fluctuations. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-96639 A Summary of the Invention

[0006] The present invention has been made to address the above-mentioned problems. That is, an object of the present invention is to provide a vehicle weight estimation device that can estimate the weight of a vehicle with higher accuracy than in the past.

[0007] In order to solve the above problems, the vehicle weight estimation device (100) according to the present invention comprises: A weight estimation device (100) for a vehicle (10) having a towing vehicle (11) and a towed vehicle (12) towed by the towing vehicle (11), comprising: of the vehicle (10) during a given period of time. Driving force and acceleration Estimating the weight of the vehicle (10) based on The system is configured to determine whether or not a specific condition is established indicating that the accuracy of the estimated weight of the vehicle (10) is higher than the accuracy of the estimated weight of the registered vehicle (10) based on at least one of the fluctuations in the driving force, the fluctuations in the acceleration, and the fluctuations in the gradient of the road surface on which the vehicle is traveling, and if the specific condition is established, to change the registered weight of the vehicle (10) to the weight of the vehicle (10) estimated based on the driving force and the acceleration during the specified period.

[0008] According to the present invention, when the estimated vehicle weight is more accurate than the registered vehicle weight (when the estimation accuracy is high), the registered vehicle weight is updated (replaced) with the estimated weight, so that the vehicle weight closer to the actual weight can be registered.

[0009] In the above description, in order to facilitate understanding of the present invention, the names and / or symbols used in the embodiments described below are added in parentheses to the configurations of the invention corresponding to those embodiments. However, each component of the present invention is not limited to the embodiments defined by the names and / or symbols. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing the configuration of a vehicle. [Diagram 2] FIG. 2 is a flowchart showing the vehicle weight update routine. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a vehicle weight estimation device according to an embodiment of the present invention will be described. In the following description, the vehicle weight estimation device may be abbreviated to "estimation device".

[0012] (Configuration of the estimation device) 1 is a diagram showing the configuration of a vehicle 10. An estimation device 100 is mounted on the vehicle 10. The vehicle 10 has a towing vehicle 11 and a towed vehicle 12 towed by the towing vehicle 11. The estimation device 100 according to this embodiment estimates the weight of the vehicle 10. The weight of the vehicle 10 estimated by the estimation device 100 is the total weight of the towing vehicle 11 and the towed vehicle 12.

[0013] As shown in FIG. 1, the estimation device 100 includes a driving assistance ECU 101, an engine ECU 102, a brake ECU 103, an ACC switch 104, a vehicle speed sensor 105, an acceleration sensor 106, an engine actuator 107, an accelerator sensor 108, a transmission 109, a brake actuator 110, and a brake sensor 111. Each of the driving assistance ECU 101, the engine ECU 102, and the brake ECU 103 includes a computer including a CPU, a ROM, a RAM, a readable / writable non-volatile memory, an interface, and the like. The CPU sequentially executes a predetermined program (routine) to read data, perform numerical calculations, and output the calculation results. The ROM stores in advance the programs executed by the CPU, lookup tables (maps), and the like. The RAM can temporarily store data. These ECUs can communicate data with each other (can exchange data) via a CAN (Controller Area Network).

[0014] The driving assistance ECU 101 is a central control device that provides driving assistance to the driver, and is configured to be capable of executing adaptive vehicle distance control, which will be described later. An ACC switch 104 is connected to the driving assistance ECU 101. The ACC switch 104 is an operating device that the driver can operate to start and end ACC, which will be described later. The driving assistance ECU 101 starts ACC when it detects that the ACC switch 104 has been turned ON, and ends ACC when it detects that the ACC switch 104 has been turned OFF. The driving assistance ECU 101 is further connected to a vehicle speed sensor 105 and an acceleration sensor 106. The driving assistance ECU 101 can acquire the detection result of the vehicle speed by the vehicle speed sensor 105 and the detection result of the acceleration by the acceleration sensor 106. Furthermore, the driving assistance ECU 101 can send a driving force change command to the engine ECU 102 to instruct it to increase or decrease the driving force transmitted to the driving wheels (hereinafter referred to as "vehicle driving force"), and can send a braking command to the brake ECU 103 to instruct it to increase or decrease the braking force of the vehicle 10 (hereinafter referred to as "vehicle braking force").

[0015] The engine ECU 102 is connected to an engine actuator 107, an accelerator sensor 108, and a transmission 109. The engine actuator 107 includes a throttle valve actuator that changes the opening degree of a throttle valve of the engine. The accelerator sensor 108 is configured to acquire the operation amount of an accelerator pedal (not shown). The engine ECU 102 can change the driving force (torque) generated by the engine, which is the driving force source of the vehicle 10, by driving the engine actuator 107 according to the operation amount of the accelerator pedal. The driving force generated by the engine is transmitted to the driving wheels via the transmission 109. The engine ECU 102 controls the engine actuator 107 and the transmission 109 so that the driving force that changes according to the acquired operation amount of the accelerator pedal is transmitted to the driving wheels of the vehicle 10. In this way, the engine ECU 102 can control the vehicle driving force by controlling the engine actuator 107 and the transmission 109. When the vehicle 10 is a hybrid vehicle, the engine ECU 102 can control the vehicle driving force generated by either or both of the "engine and the electric motor" as the driving force source of the vehicle 10. Furthermore, when the vehicle 10 is an electric vehicle, the engine ECU 102 can control the vehicle driving force generated by the electric motor as the driving force source.

[0016] Furthermore, when the engine ECU 102 receives a driving force change command from the driving assistance ECU 101, the engine ECU 102 can increase or decrease the vehicle driving force by automatically controlling the engine actuator 107 and the transmission 109 in accordance with the content of the driving force change command. That is, the engine ECU 102 can change the vehicle driving force (in other words, accelerate or decelerate the vehicle 10) without the driver needing to operate the accelerator pedal by controlling the engine actuator 107 and the transmission 109 in accordance with the driving force change command.

[0017] The brake ECU 103 is connected to a brake actuator 110 and a brake sensor 111. The brake sensor 111 is configured to acquire the amount of operation of a brake pedal (not shown). The brake actuator 110 adjusts the hydraulic pressure (master cylinder pressure) of hydraulic fluid of a friction brake mechanism provided on each wheel, and applies a friction braking force corresponding to the hydraulic pressure to each wheel. The brake ECU 103 determines a driver-requested deceleration based on the amount of operation of the brake pedal detected by the brake sensor 111, and controls the brake actuator 110 so that the vehicle 10 decelerates at the driver-requested deceleration. The driving assistance ECU 101 can acquire the amount of operation of the brake pedal by the brake sensor 111 (in other words, information indicating the magnitude of the vehicle braking force by the friction brake mechanism) via the brake ECU 103. Note that the vehicle 10 may have a pressure sensor that detects the hydraulic pressure of the hydraulic fluid of the friction brake mechanism (master cylinder pressure) instead of or in addition to the brake sensor 111. In this case, the driving assistance ECU 101 can acquire the detection result of the hydraulic pressure of the hydraulic oil by the pressure sensor via the brake ECU 103 as information indicating the magnitude of the vehicle braking force by the friction brake mechanism.

[0018] Furthermore, when the brake ECU 103 receives a braking command from the driving assistance ECU 101, the brake ECU 103 controls the operation of the brake actuator 110 so that the vehicle 10 decelerates at a required deceleration included in the braking command. That is, the brake ECU 103 drives the brake actuator 110 in response to the braking command, thereby controlling the vehicle braking force and reducing the speed of the vehicle 10. In this way, when the brake ECU 103 receives a braking command from the driving assistance ECU 101, the brake ECU 103 can control the vehicle braking force without requiring the driver to operate the brake pedal.

[0019] The vehicle speed sensor 105 is configured to repeatedly detect the vehicle speed at a predetermined cycle and sequentially transmit a signal representing the vehicle speed to the driving assistance ECU 101. The acceleration sensor 106 is configured to repeatedly detect the acceleration of the vehicle 10 at a predetermined cycle and sequentially transmit a signal representing the acceleration to the driving assistance ECU 101.

[0020] (Outline of adaptive vehicle distance control) The driving assistance ECU 101 is configured to be able to execute the following distance control. The following distance control may be referred to as "adaptive cruise control". In this embodiment, the following distance control may be abbreviated as "ACC". The ACC includes two types of control: a constant speed running mode control and a following driving mode control. The constant speed running mode is a mode in which the acceleration of the vehicle 10 is controlled so that the running speed of the vehicle 10 matches a target speed (set speed) without the driver needing to operate the accelerator pedal and the brake pedal. The following driving mode is a control in which the vehicle 10 is made to follow the preceding vehicle while maintaining the distance between the preceding vehicle running immediately before the vehicle 10 and the vehicle 10 at a target distance. The ACC is well known. For details of ACC, see, for example, Japanese Patent Application Publication No. 2014-148293, Japanese Patent Application Publication No. 2006-315491, Japanese Patent No. 4172434, and Japanese Patent No. 4929777. A computer program for executing ACC is stored in advance in the ROM of the driving assistance ECU 101. The CPU of the driving assistance ECU 101 reads out the computer program stored in the ROM, expands it in the RAM, and executes it. This realizes ACC.

[0021] When the driving assistance ECU 101 detects that the ACC switch 104 has been turned ON, the driving assistance ECU 101 starts the ACC. Specifically, when the driving assistance ECU 101 detects that the ACC switch 104 has been turned ON, the driving assistance ECU 101 determines whether or not there is a preceding vehicle that is traveling ahead of the vehicle 10 and that the vehicle 10 should follow. Then, when the driving assistance ECU 101 determines that there is no preceding vehicle as described above, it executes control of the constant speed traveling mode, and when it determines that there is a preceding vehicle as described above, it executes control of the following traveling mode. During the execution of control of the constant speed traveling mode, the driving assistance ECU 101 determines a target acceleration so that the vehicle speed of the vehicle 10 matches a predetermined target speed. On the other hand, during the execution of control of the following traveling mode, the driving assistance ECU 101 determines a target acceleration based on the "deviation between the distance to the vehicle to be followed and the target distance" and the "relative speed of the vehicle to be followed with respect to the vehicle 10" so that the vehicle 10 follows the preceding vehicle while maintaining a predetermined distance from the preceding vehicle. Then, the driving assistance ECU 101 controls the vehicle driving force and the vehicle braking force so that the actual acceleration of the vehicle 10 coincides with the target acceleration (or so that the difference between the actual acceleration of the vehicle 10 and the target acceleration becomes smaller).

[0022] (Method of estimating vehicle weight) Since the acceleration of the vehicle 10 is inversely proportional to the weight of the vehicle 10, in order to make the actual acceleration of the vehicle 10 coincide with the target acceleration, or in order to reduce the difference between the actual acceleration of the vehicle 10 and the target acceleration, the weight of the vehicle 10 must be known. For this reason, the driving assistance ECU 101 estimates the weight of the vehicle 10 and registers the estimated weight of the vehicle 10. The driving assistance ECU 101 then controls the vehicle driving force and the vehicle braking force by referring to the registered weight of the vehicle 10.

[0023] In this embodiment, the driving assistance ECU 101 calculates the weight of the vehicle 10 based on the output vehicle driving force F dv and the acceleration A in the longitudinal direction of the vehicle 10 (hereinafter referred to as "longitudinal acceleration A"). dvA method of calculating the weight of the vehicle 10 based on the longitudinal acceleration A of the vehicle 10 is well known. In this embodiment, the driving assistance ECU 101 calculates the weight of the vehicle 10 using the following formula (1). M=(F dv -F air -F rl ) / (A+g·sinθ) (Equation (1)) M: Weight of 10 vehicles F dv : Vehicle driving force being output F air :Air resistance on vehicle 10 F rl : Road resistance when the vehicle 10 is traveling A: longitudinal acceleration of the vehicle 10 due to the driving force g: gravity θ: Road surface gradient (angle relative to the horizontal direction of the road surface)

[0024] Vehicle driving force F dv is determined by the driving force (driving torque) output by the engine and the shift position of the shift mechanism. For this reason, the driving assistance ECU 101 repeatedly acquires the driving force (driving torque) output by the engine and the current shift position of the shift mechanism from the engine ECU 102 at a predetermined cycle, and calculates the vehicle driving force F from the acquired driving force output by the engine and the shift position of the shift mechanism. dv In this embodiment, the driving assistance ECU 101 acquires the detection result of the accelerator pedal operation amount by the accelerator sensor as a signal representing the driving force output by the engine, and calculates the driving force output by the engine based on the accelerator pedal operation amount. However, the vehicle 10 may have a sensor (e.g., a torque sensor) that detects the driving force of the engine. In this case, the driving assistance ECU 101 calculates the vehicle driving force F dv The detection result of the engine driving force by this sensor is used to calculate.

[0025] Air resistance F on vehicle 10 airis proportional to the square of the vehicle speed. Therefore, the driving assistance ECU 101 calculates the air resistance F based on the vehicle speed obtained from the vehicle speed sensor 105 and a predetermined coefficient. air The road resistance F when the vehicle 10 is traveling is calculated. rl Therefore, the driving assistance ECU 101 determines whether the road resistance F rl A predetermined value (a value registered in advance) is used as the value of . The longitudinal acceleration A of the vehicle 10 is acquired from the acceleration sensor 106. The driving assistance ECU 101 may estimate the longitudinal acceleration A of the vehicle 10 based on the amount of operation of the accelerator pedal and the amount of operation of the brake pedal (master cylinder pressure). The road surface gradient θ is estimated based on the acceleration of the vehicle 10 (acceleration in the longitudinal direction and in the direction perpendicular to the road surface) acquired from the acceleration sensor 106. However, the vehicle 10 may have a gradient sensor. In this case, the detection result of the road surface gradient θ by this gradient sensor is used to calculate the weight M of the vehicle 10.

[0026] In this embodiment, the driving assistance ECU 101 repeatedly calculates the weight M of the vehicle 10 using the above formula (1) a number of times. In other words, the driving assistance ECU 101 uses parameters acquired a number of times within a predetermined period to calculate the weight M of the vehicle 10 at each of a number of points in time within the predetermined period. Then, the driving assistance ECU 101 sets the average value of these calculation results as the "estimated weight of the vehicle 10." In other words, the vehicle driving force F repeatedly calculated and acquired within the predetermined period is dv and the weight of the vehicle 10 is estimated based on the longitudinal acceleration A of the vehicle 10. For ease of explanation, the weight M of the vehicle 10 calculated by the above formula (1) (i.e., the weight of the vehicle 10 at each point in time) is referred to as the "instantaneous weight M" to distinguish it from the "estimated weight of the vehicle 10."

[0027] (Vehicle weight update process) Next, the vehicle weight update process will be described. In order to make the actual acceleration of the vehicle 10 coincide with the target acceleration, it is required that the actual weight of the vehicle 10 coincides with the estimated weight of the vehicle 10 (or the difference is small). Therefore, the driving assistance ECU 101 repeatedly executes the process of "estimating the weight of the vehicle 10, and if it is determined that the accuracy of the estimated weight of the vehicle 10 is higher than the accuracy of the registered weight of the vehicle 10, changing (in other words, updating) the registered weight of the vehicle 10 to the estimated weight of the vehicle 10" during the execution of the ACC. This is an outline of the vehicle weight update process. By executing such a vehicle weight update process, it is possible to increase the accuracy of the registered weight of the vehicle 10 (in other words, to reduce the difference between the weight of the registered vehicle 10 and the actual weight of the vehicle 10).

[0028] The vehicle weight update process includes the following processes (1) to (4). (1) An environment determination process for repeatedly determining at a predetermined interval whether the current driving environment of the vehicle 10 is an "environment in which the weight of the vehicle 10 can be estimated" or not. (2) An instantaneous weight calculation process for calculating the instantaneous weight M of the vehicle 10 using the above formula (1) when the driving environment of the vehicle 10 is determined to be an "environment in which the weight of the vehicle 10 can be estimated" by the environment determination process. (3) A weight estimation process for estimating the weight of the vehicle 10 using instantaneous weight M of the vehicle 10 calculated multiple times during the predetermined period (i.e., instantaneous weight M of the vehicle 10 at multiple points in time during the predetermined period), which is determined to have continued for a predetermined period of time. (4) A driving stability determination process for determining whether the driving stability of the vehicle 10 during the predetermined period (the period during which the "environment in which the weight of the vehicle 10 can be estimated" continued) (hereinafter referred to as the "first driving stability") is higher than the driving stability of the vehicle 10 during the period during which the parameters used to estimate the weight of the registered vehicle 10 (i.e., the parameters used to calculate the instantaneous weight M used to estimate the weight of the registered vehicle 10) were acquired (hereinafter referred to as the "second driving stability") (5) A registration update process for changing (updating) the registered weight of the vehicle 10 to a weight estimated based on the instantaneous weight M calculated in the instantaneous weight calculation process when it is determined that the first driving stability is higher than a predetermined standard and is higher than the second driving stability.

[0029] Each of the processes (1) to (5) will be explained below.

[0030] (1) Environment determination process According to the method of calculating the instantaneous weight M of the vehicle 10 using the above formula (1), the driving environment of the vehicle 10 is such that the vehicle driving force F dv In an environment where at least one of the following fluctuates significantly (in this embodiment, "fluctuation" means "change in value over time"): longitudinal acceleration A, longitudinal acceleration B, and road surface gradient θ (in other words, in an environment where at least one of these values ​​is unstable), the instantaneous weight M may not be calculated accurately. dv Based on the fluctuation of the vehicle driving force F, the fluctuation of the longitudinal acceleration A, and the fluctuation of the road surface gradient θ, it is determined whether or not the driving environment of the vehicle 10 is an "environment in which the weight of the vehicle 10 can be estimated." dv , the vehicle driving force F dv The driving assistance ECU 101 uses the deviation of the vehicle driving force F dv The calculation of the vehicle driving force F at the present time (current time) and within a predetermined period in the past (or a predetermined number of times) from the present time (current time) is repeatedly performed at a predetermined cycle. dv , the deviation of the longitudinal acceleration A and the road surface gradient θ are calculated. If any of these deviations is equal to or smaller than a predetermined value, the driving assistance ECU 101 determines that the current driving environment of the vehicle 10 is an environment in which the weight of the vehicle 10 can be estimated. For example, the threshold value of the deviation of the longitudinal acceleration A is set to 0.08 m / sec 2 , vehicle driving force F dvA threshold value of 16N can be applied to the deviation of the road surface gradient θ, and a threshold value of 2° (deg) can be applied to the deviation of the road surface gradient θ. On the other hand, if at least one of these calculated deviations exceeds the threshold value, the driving assistance ECU 101 determines that the current (current time) driving environment of the vehicle 10 is not "an environment in which the weight of the vehicle 10 can be estimated." Note that the specific length (or number of times) of the "predetermined period (or predetermined number of times)" is not particularly limited and is set appropriately. Note that these threshold values ​​can also be said to be the minimum conditions for determining that the current driving environment of the vehicle 10 is "an environment in which the weight of the vehicle 10 can be estimated." In this case, when the deviation of the longitudinal acceleration A is 0 m / sec 2 , vehicle driving force F dv When the deviation of the road surface gradient θ is 0N and the threshold of the deviation of the road surface gradient θ is 0° (deg), it can be said that this is the best condition for determining that the current driving environment of the vehicle 10 is an "environment in which the weight of the vehicle 10 can be estimated."

[0031] In addition, the driving assistance ECU 101 detects the vehicle driving force F dv Alternatively, the driving assistance ECU 101 may use two of the deviations in the vehicle driving force F, the deviation in the longitudinal acceleration A, and the deviation in the road surface gradient θ to determine whether the current driving environment of the vehicle 10 is "an environment in which the weight of the vehicle 10 can be estimated." In this case, if both of the two deviations used to determine the driving stability of the vehicle 10 are equal to or smaller than a predetermined threshold, the driving assistance ECU 101 determines that the current driving environment of the vehicle 10 is "an environment in which the weight of the vehicle 10 can be estimated." On the other hand, if the threshold value of at least one of the values ​​exceeds the threshold, the driving assistance ECU 101 determines that the current driving environment of the vehicle 10 is not "an environment in which the weight of the vehicle 10 can be estimated." Furthermore, the driving assistance ECU 101 determines whether the current driving environment of the vehicle 10 is "an environment in which the weight of the vehicle 10 can be estimated." dv Alternatively, it may be possible to determine whether the current driving environment of the vehicle 10 is an "environment in which the weight of the vehicle 10 can be estimated" by using any one of the deviation in the longitudinal acceleration A, the deviation in the road surface gradient θ, and the deviation in the road surface gradient θ.

[0032] (2) Instantaneous weight calculation process The driving assistance ECU 101 repeatedly acquires, at a predetermined cycle, parameters used to calculate the instantaneous weight M of the vehicle 10. Specifically, the driving assistance ECU 101 acquires, as these parameters, the driving force (driving torque) output by the engine, the current shift position of the shift mechanism, the vehicle speed detected by the vehicle speed sensor 105, and the acceleration (gravity) detected by the acceleration sensor 106.

[0033] Then, while the current driving environment of the vehicle 10 is determined to be an "environment in which the weight of the vehicle 10 can be estimated," the driving assistance ECU 101 repeatedly calculates the instantaneous weight M of the vehicle 10 at a predetermined cycle using the above-mentioned formula (1). Specifically, the driving assistance ECU 101 calculates the vehicle driving force F based on the driving force (driving torque) output by the engine and the current shift position of the shift mechanism. dv Calculate the air resistance F acting on the vehicle 10 based on the vehicle speed. air The driving assistance ECU 101 calculates the road surface gradient θ based on the calculated instantaneous weight M of the vehicle 10, the acquired longitudinal acceleration A, and the calculated vehicle driving force F dv , and the calculated road surface gradient θ are temporarily stored.

[0034] (3) Weight estimation process The driving assistance ECU 101 judges whether or not a stable condition, which is a condition for regarding the traveling state of the vehicle 10 as being stable, is satisfied. Specifically, the driving assistance ECU 101 judges whether or not the traveling environment of the vehicle 10 has continued to be "an environment in which the weight of the vehicle 10 can be estimated" for a predetermined period of time. Then, the driving assistance ECU 101 judges that the stable condition is satisfied when the traveling environment of the vehicle 10 has continued to be "an environment in which the weight of the vehicle 10 can be estimated" for a predetermined period of time. Thus, in this embodiment, the driving assistance ECU 101 judges whether or not the stable condition is satisfied based on the length of the period during which the traveling environment of the vehicle 10 has been determined to be "an environment in which the weight of the vehicle 10 can be estimated". Note that the length of this predetermined period is not particularly limited, but at least the vehicle driving force Fdv is used to calculate the deviations of the vehicle driving force Fdv, the longitudinal acceleration A, and the road surface gradient θ.dv The first period is longer than the period during which the calculation of the vehicle weight M, the acquisition of the longitudinal acceleration A, and the calculation of the road surface gradient θ were repeatedly performed. For ease of explanation, the predetermined period when the "environment in which the weight of the vehicle 10 can be estimated" continues for a predetermined period is referred to as a "first period." When the driving assistance ECU 101 determines that the stability condition is satisfied, the driving assistance ECU 101 calculates an average value of the instantaneous weight M repeatedly calculated within the first period, and sets the calculated average value of the instantaneous weight M as the estimated value of the weight of the vehicle 10.

[0035] (4) Driving stability judgment processing The driving assistance ECU 101 determines whether or not a specific condition is established that indicates that the accuracy of the estimation of the weight of the vehicle 10 (the average value of the instantaneous weight M repeatedly calculated within a first period) is higher (or can be considered to be higher) than the accuracy of the estimation of the registered weight of the vehicle 10. In this embodiment, when the driving assistance ECU 101 determines that "the first driving stability is higher than the second driving stability", it determines that "the accuracy of the estimation of the estimated weight of the vehicle 10 is higher than the accuracy of the estimation of the registered weight of the vehicle 10" (i.e., it determines that the specific condition is established).

[0036] A specific method for determining whether or not the specific condition exists is as follows. The currently registered weight of the vehicle 10 is a weight estimated by the above-mentioned processes (1) to (3) executed in the past. For ease of explanation, the first period when the weight of the currently registered vehicle 10 was estimated will be distinguished from the second period. The deviation of the longitudinal acceleration A, the vehicle driving force F dv Priority is preset for the deviation of the longitudinal acceleration A and the deviation of the road surface gradient θ. For example, the priority of the deviation of the longitudinal acceleration A is the highest, the second is the deviation of the vehicle driving force F dvThe deviation of the longitudinal acceleration A has a higher priority, and the deviation of the road surface gradient θ has the lowest priority. The driving assistance ECU 101 first compares the values ​​of the deviations of the longitudinal acceleration A, which has the highest priority. If the deviation of the longitudinal acceleration A in the first period is smaller than the deviation of the longitudinal acceleration A in the second period, the driving assistance ECU 101 determines that the specific condition is met, and if the deviation of the longitudinal acceleration A in the first period is greater than the deviation of the longitudinal acceleration A in the second period, the driving assistance ECU 101 determines that the specific condition is not met. If the deviation of the longitudinal acceleration A in the first period and the deviation of the longitudinal acceleration A in the second period are the same, the driving assistance ECU 101 compares the deviation of the vehicle driving force F, which has the second highest priority, with the deviation of the longitudinal acceleration A in the first period. dv In this case, the driving assistance ECU 101 compares the vehicle driving force F dv The deviation of the vehicle driving force F dv If the deviation is smaller than the deviation of the first period, it is determined that the specific condition is satisfied, and the vehicle driving force F dv The deviation of the vehicle driving force F dv If the difference is greater than the deviation from the first period, it is determined that the specific condition is not satisfied. dv and the vehicle driving force F in the second period dv If the deviations in the road surface gradient θ in the first period and the road surface gradient θ in the second period are the same, the driving assist ECU 101 compares the values ​​of the deviations in the road surface gradient θ with each other, which has the lowest priority (the third highest priority). In this case, if the deviation in the road surface gradient θ in the first period is smaller than the deviation in the road surface gradient θ in the second period, the driving assist ECU 101 determines that the specific condition is met, and if the deviation in the road surface gradient θ in the first period is the same as or larger than the deviation in the road surface gradient θ in the second period, the driving assist ECU 101 determines that the specific condition is not met.

[0037] As described above, the driving assistance ECU 101 calculates the deviation of the longitudinal acceleration A and the vehicle driving force F dv The driving assistance ECU 101 may determine whether or not the specific condition is satisfied based on all of the deviation of the longitudinal acceleration A and the deviation of the road surface gradient θ, or may determine whether or not the specific condition is satisfied based on one or two of them.dv Whether or not the specific condition is met may be determined based on at least one of the deviation in the road surface gradient θ and the deviation in the road surface gradient θ.

[0038] (5) Registration renewal process When the driving assistance ECU 101 determines that the driving stability of the vehicle 10 satisfies the stability condition and the specific condition is established, it changes (updates) the registered weight of the vehicle 10 to a weight estimated based on the instantaneous weight M of the vehicle 10 calculated in the instantaneous weight calculation process. Furthermore, the driving assistance ECU 101 registers the first driving stability as the second driving stability. That is, the driving assistance ECU 101 updates the currently registered deviation of the longitudinal acceleration A, the vehicle driving force F dv and the deviation of the road surface gradient θ (the deviation of the longitudinal acceleration A in the second period, the vehicle driving force F dv and the deviation of the road surface gradient θ) are expressed as "the deviation of the longitudinal acceleration A in the first period, the vehicle driving force F dv and deviation of road surface gradient θ.

[0039] On the other hand, when the driving assistance ECU 101 determines that the driving stability of the vehicle 10 does not satisfy the stability condition or when the driving assistance ECU 101 determines that the specific condition is not established, the registered weight of the vehicle 10 and the second driving stability are not changed. In a state where the registration update process has not been executed even once, the registered weight of the vehicle 10 is held at an initial value. In a state where the driving assistance ECU 101 determines that the driving stability of the vehicle 10 does not satisfy the stability condition, the driving assistance ECU 101 does not need to determine whether the specific condition is established.

[0040] Then, when it is determined that the specific condition is satisfied, the estimation device 100 estimates the weight of the vehicle 10 by calculating an average value of the calculated instantaneous weights M of the vehicle 10, and changes (updates) the registered weight of the vehicle 10 to the estimated weight of the vehicle 10. Note that, when the weight of the registered vehicle 10 is an initial value, there is no "parameter used to estimate the weight of the registered vehicle 10." Therefore, in this case, the driving assistance ECU 101 considers that the specific condition is satisfied when the running stability of the vehicle 10 satisfies the stable condition. Then, the driving assistance ECU 101 updates (changes) the registered weight of the vehicle 10 to the estimated weight of the vehicle 10, and registers the first running stability as the second running stability.

[0041] In this way, when the driving assistance ECU 101 estimates the weight of the vehicle 10 with higher accuracy than the registered weight of the vehicle 10, the driving assistance ECU 101 updates the registered weight of the vehicle 10 to the weight of the vehicle 10 estimated with higher accuracy. This makes it possible to register a weight of the vehicle 10 that is closer to reality. Then, the driving assistance ECU 101 executes ACC using the registered weight of the vehicle 10 in this way, thereby making it possible to bring the actual acceleration of the vehicle 10 closer to the target acceleration (in other words, it is possible to reduce the difference between the actual acceleration and the target acceleration of the vehicle 10).

[0042] (Specific action) Next, a specific operation of the driving assistance ECU 101 will be described. The CPU of the driving assistance ECU 101 repeatedly executes the "vehicle weight update routine" shown in the flowchart of FIG. 2 at a predetermined cycle. This realizes the above-mentioned vehicle weight update process. In the following description, the CPU of the driving assistance ECU 101 may be abbreviated to simply "CPU". Note that an initial value of the weight of the vehicle 10 used when executing ACC is stored in advance in the readable / writable non-volatile memory of the driving assistance ECU 101. The CPU also repeatedly acquires the vehicle speed detected by the vehicle speed sensor 105 and the acceleration (gravity) detected by the acceleration sensor 106 at a predetermined cycle. Furthermore, the CPU also repeatedly acquires the driving force (driving torque) output by the engine and the current shift position of the shift mechanism at a predetermined cycle, and calculates the vehicle driving force F based on the acquired driving force (driving torque) and the current shift position of the shift mechanism. dv That is, the CPU sequentially calculates the vehicle speed, the longitudinal acceleration A, and the vehicle driving force F at each time point during the execution of the vehicle weight update routine. dv has been obtained.

[0043] In step S101, the CPU determines whether or not ACC is being executed. Specifically, the CPU determines whether or not ACC switch 104 has been turned ON. Then, when the CPU has not detected that ACC switch 104 has been turned ON, or when the CPU has detected that ACC switch 104 has been turned OFF, it determines that ACC is not being executed. In these cases, the CPU advances the process to step S102. On the other hand, when the CPU has detected that ACC switch 104 has been turned ON and has not subsequently detected that ACC switch 104 has been turned OFF, it determines that ACC is being executed. In this case, the CPU advances the process to step S105.

[0044] In step S102, the CPU determines whether the process of step S110, which will be described later, has been executed at least once since the ignition switch was turned on until now. If the CPU determines that the process of step S110 has not been executed at least once, the CPU proceeds to step S103. On the other hand, if the CPU determines that the process of step S110 has already been executed at least once, the CPU proceeds to step S104.

[0045] In step S103, the CPU holds the weight of the vehicle 10 (i.e., the initial value of the weight of the vehicle 10) that was registered before starting this vehicle weight update routine. Therefore, in this case, the initial value of the weight of the vehicle 10 is used for executing ACC. Then, the CPU temporarily ends this vehicle weight update routine.

[0046] In step S104, the CPU holds the registered weight and second running stability of the vehicle 10, i.e., the weight of the vehicle 10 updated in the previous step S110 and the running stability of the vehicle 10 determined to be "Y" in the previous step S107 (first running stability). Therefore, in this case, the weight of the vehicle 10 updated in the previous step S110 is used for executing the ACC. Then, the CPU temporarily ends this vehicle weight update routine.

[0047] In step S105, the CPU determines whether or not the current driving environment of the vehicle 10 is an environment in which the weight of the vehicle 10 can be estimated. If the CPU determines that the current driving environment of the vehicle 10 is not an environment in which the weight of the vehicle 10 can be estimated, the CPU proceeds to step S102. On the other hand, if the CPU determines that the current driving environment of the vehicle 10 is an environment in which the weight of the vehicle 10 can be estimated, the CPU proceeds to step S106. As described above, the deviation of the longitudinal acceleration A, the vehicle driving force F, and the like are used to determine whether or not the driving environment of the vehicle 10 is "an environment in which the weight of the vehicle 10 can be estimated." dvand the deviation of the road surface gradient θ are used. Therefore, if the number of times this vehicle weight update routine is repeated is less than the predetermined number of times, it is not possible to determine whether the traveling environment of the vehicle 10 is an "environment in which the weight of the vehicle 10 can be estimated." Therefore, in this case, the CPU advances the process to step S102.

[0048] In step S106, the CPU acquires parameters used for calculating the instantaneous weight M of the vehicle 10 and judging the stability of the running state of the vehicle 10. Furthermore, the CPU calculates the instantaneous weight M of the vehicle 10 using the acquired parameters. This allows the instantaneous weight M of the vehicle 10 at a certain point in time while the ACC is being executed to be calculated. Then, the CPU advances the process to step S107.

[0049] In step S107, the CPU determines whether the running stability of the vehicle 10 satisfies the stable condition. In this embodiment, in step S105 of this vehicle weight update routine that is repeatedly executed, if the running state of the vehicle 10 is determined to be "an environment in which the weight of the vehicle 10 can be estimated" for a predetermined number of consecutive times ("Y" in step S105), the CPU determines that the running stability of the vehicle 10 satisfies the stable condition. On the other hand, if the number of consecutive times in which the running state of the vehicle 10 is determined to be "an environment in which the weight of the vehicle 10 can be estimated" does not reach a predetermined number, the CPU determines that the running stability of the vehicle 10 does not satisfy the stable condition. Then, if the CPU determines that the running stability of the vehicle 10 does not satisfy the stable condition, the CPU advances the process to step S102. On the other hand, if the CPU determines that the running stability of the vehicle 10 satisfies the stable condition, the CPU advances the process to step S108.

[0050] In step S108, the CPU calculates the average value of the instantaneous weight M of the vehicle 10 calculated in step S106 while the vehicle weight update routine is being repeated. That is, the CPU estimates the weight of the vehicle 10 based on the instantaneous weight M. Then, the CPU advances the process to step S109.

[0051] In step S109, the CPU determines whether or not the specific condition is satisfied. The second driving stability is stored in a readable and writable non-volatile memory. The CPU then determines whether or not the specific condition is satisfied by comparing the first driving stability (the driving stability of the vehicle 10 determined as "Y" in this step S107) with the second driving stability. If the CPU determines that the specific condition is satisfied, the CPU advances the process to step S110. On the other hand, if the CPU determines that the specific condition is not satisfied, the CPU advances the process to step S102.

[0052] In step S110, the CPU changes the registered weight of the vehicle 10 to the weight of the vehicle 10 estimated in this step S108. At the same time, the CPU registers the first driving stability as the second driving stability (stores it in a readable and writable non-volatile memory). Then, the CPU once ends this vehicle weight update routine.

[0053] According to such a vehicle weight update routine, the above-mentioned vehicle weight update process is realized. Therefore, when the weight of the vehicle is estimated with higher accuracy than the registered weight of the vehicle 10 ("Y" in step S109), the registered weight of the vehicle 10 is updated to the weight of the vehicle 10 estimated with higher accuracy (step S110). Therefore, the weight of the vehicle 10 close to the actual weight can be registered.

[0054] Although the embodiment of the present invention has been described above, the present invention is not limited to the above-mentioned embodiment.

[0055] For example, in the above embodiment, the deviation of the longitudinal acceleration A, the vehicle driving force F dv In the above embodiment, the running stability of the vehicle 10 is determined based on the deviation of the road surface gradient θ and the longitudinal acceleration A of the vehicle 10 and the vehicle driving force F dv If the weight of the vehicle 10 is estimated based on the fluctuation of the longitudinal acceleration A and the vehicle driving force F dvand the variation in road surface gradient θ (the variation in the component of gravity in a direction parallel to the road surface) can be disturbances (causes of reduced accuracy) when estimating the weight of the vehicle 10. Therefore, the determination of the running stability of the vehicle 10 can be made using an index that indicates the magnitude of the variation or the magnitude of the variation in these values, and is not limited to the deviation.

[0056] In the above embodiment, the average of the instantaneous weights M is set as the "estimated weight of the vehicle 10", but the present invention is not limited to this configuration. For example, the median or mode of the instantaneous weights M may be set as the "estimated weight of the vehicle 10".

[0057] In addition, in the above embodiment, the estimated weight of the vehicle 10 is used for ACC, but the use of the estimated weight of the vehicle 10 is not limited. That is, in the above embodiment, the vehicle weight update process is executed while the ACC is being executed, but the timing of executing the vehicle weight update process is not limited. [Explanation of symbols]

[0058] 10...vehicle, 100...estimation device, 101...driving assistance ECU, 102...engine ECU, 103...brake ECU, 104...ACC switch, 105...vehicle speed sensor, 106...acceleration sensor, 107...engine actuator, 108...accelerator sensor, 109...transmission, 110...brake actuator, 111...brake sensor

Claims

[Claim 1] A vehicle weight estimation device having a towing vehicle and a towed vehicle towed by the towing vehicle, Estimating a weight of the vehicle based on a driving force and an acceleration of the vehicle during a predetermined period of time; a determination is made as to whether or not a specific condition is satisfied, which indicates that the accuracy of the estimated weight of the vehicle is higher than the accuracy of the estimated weight of the registered vehicle, based on at least one of the fluctuation in the driving force, the fluctuation in the acceleration, and the fluctuation in the gradient of the road surface on which the vehicle is traveling, and if the specific condition is satisfied, the registered weight of the vehicle is changed to the weight of the vehicle estimated based on the driving force and the acceleration during the specified period. Vehicle weight estimation device.

Images