Vehicle weight estimation device and damping force adjustable suspension system

Abstract

To achieve memory usage reduction while realizing vehicle weight estimation with high accuracy.SOLUTION: A vehicle weight estimation device 10, which estimates a weight of a vehicle during travelling, has: an acceleration acquisition part 13 that acquires acceleration of a vehicle and calculates continuous average value of acceleration for a prescribed number of times; a drive power acquisition part 12 that acquires drive power of the vehicle, and calculates continuous average value of drive power for a prescribed number of times; and a vehicle weight estimation part 14 that estimates weight of the vehicle by use of an equation of motion (3) from the continuous average value of acceleration and the continuous average value of drive power.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a vehicle weight estimation device and a damping force adjustable suspension system. [Background technology]

[0002] In recent years, various control systems have been implemented in vehicles such as automobiles to improve driving safety and comfort. To properly implement these vehicle driving controls, it is necessary to accurately determine the weight of the vehicle while it is in motion.

[0003] To estimate the weight of this vehicle, for example, Patent Document 1 describes a technique for estimating the vehicle's weight (vehicle weight) by acquiring state variables dependent on the vehicle using sensors and fitting them to equations of motion. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2002-274138 [Overview of the project] [Problems that the invention aims to solve]

[0005] According to the technology described in Patent Document 1, in order to minimize the effects of errors, a large number of vehicle weight estimation results using equations of motion are stored, and the final vehicle weight is determined from the regression line of these numerous estimation results. Therefore, although highly accurate vehicle weight estimation is possible, a large amount of memory is used to store the numerous estimation results. Thus, there was room for improvement in terms of reducing memory usage.

[0006] One object of the present invention is to provide a vehicle weight estimation device and a damping force adjustable suspension device that can reduce memory usage while achieving highly accurate vehicle weight estimation. Other objects of the present invention will become apparent to those skilled in the art by referring to the embodiments and best embodiments described below, as well as the accompanying drawings. [Means for solving the problem]

[0007] The following are examples of embodiments of the present invention to facilitate understanding of its outline.

[0008] In the first embodiment, a vehicle weight estimation device for estimating the weight of a vehicle in motion includes an acceleration acquisition unit that acquires the acceleration of the vehicle at predetermined intervals and calculates a continuous average value of the acceleration for a predetermined number of times or a cumulative number of times, and a driving force acquisition unit that acquires the driving force of the vehicle at predetermined intervals and calculates a continuous average value of the driving force for a predetermined number of times or a cumulative number of times, A vehicle weight estimation unit that estimates the weight of the vehicle using an equation of motion from the continuous average value of the acceleration and the continuous average value of the driving force, The vehicle weight estimation unit further includes a counter that counts the current number of times relative to a predetermined number of times, and a storage unit that stores only the continuous average value of the acceleration and the continuous average value of the driving force at the (n-1)th time when the current number is the nth time, and the equation of motion satisfies the following equation (3).

number

[0009] According to the first embodiment, a vehicle weight estimation device can be provided that can reduce memory usage while achieving highly accurate vehicle weight estimation.

[0010] Those skilled in the art will readily understand that the embodiments of the present invention illustrated can be further modified without departing from the spirit of the invention. [Brief explanation of the drawing]

[0011] [Figure 1] This is a block diagram showing the configuration of a vehicle weight estimation device according to an embodiment of the present invention. [Figure 2] This is an operation flowchart of the vehicle weight estimation device according to an embodiment of the present invention. [Figure 3] This figure is included to illustrate the method for calculating the continuous average value used in the vehicle weight estimation device according to an embodiment of the present invention. [Figure 4] This is a block diagram showing the configuration of the damping force adjustable suspension device of Example 1. [Figure 5] This is a block diagram showing an example of the configuration of the vehicle weight estimation unit in Example 1. [Figure 6] This is a block diagram showing an example of the configuration of the target value calculation unit in Example 1. [Figure 7] This is a flowchart showing the basic processing operation of the damping force adjustable suspension system of Example 1. [Figure 8] This flowchart shows the detailed procedure for the vehicle weight estimation process in Example 1. [Figure 9] This flowchart shows the detailed procedure for calculating the target value in Example 1. [Figure 10] This diagram is used to illustrate the front-to-rear load distribution of a vehicle. [Figure 11] This is a block diagram showing the configuration of the target value calculation unit in Example 2. [Figure 12] This flowchart shows the detailed procedure for calculating the target value in Example 2. [Figure 13] This figure schematically shows an example of the configuration of a vehicle having the vehicle weight estimation device of Example 1 or 2. [Modes for carrying out the invention]

[0012] The best embodiments described below are used to facilitate understanding of the present invention. Therefore, those skilled in the art should note that the present invention is not unduly limited by the embodiments described below.

[0013] Hereinafter, one embodiment of the present invention (hereinafter referred to as "this embodiment") will be described in detail.

[0014] Figure 1 is a block diagram showing the configuration of the vehicle weight estimation device 10 of this embodiment. The vehicle weight estimation device 10 of this embodiment can estimate the weight of a vehicle in motion and, as an example, includes a driving force calculation unit 11, a driving force acquisition unit 12, an acceleration acquisition unit 13, and a vehicle weight estimation unit 14.

[0015] The drive force calculation unit 11 has the function of calculating the vehicle's drive force according to the torque applied to the wheels. The drive force calculation unit 11 supplies the vehicle's drive force F obtained by the calculation to the drive force acquisition unit 12. The method for calculating the drive force will be described later.

[0016] The driving force acquisition unit 12 acquires the vehicle's driving force F from the driving force calculation unit 11 and has the function of calculating the continuous average value F' of the driving force F for a predetermined number of times. The driving force calculation unit 11 supplies the calculated continuous average value F' of the driving force F to the vehicle weight estimation unit 14. The method for calculating the continuous average value F' of the driving force F will be described later.

[0017] The acceleration acquisition unit 13 acquires the acceleration a of the vehicle and has the function of calculating the continuous average value a' of acceleration a for a predetermined number of times. The acceleration acquisition unit 13 supplies the calculated continuous average value a' of acceleration a to the vehicle weight estimation unit 14. The method for acquiring acceleration a and the method for calculating the continuous average value a' of acceleration a will be described later.

[0018] The vehicle weight estimation unit 14 has the function of estimating the vehicle weight m using the equation of motion from the continuous average value F' of the driving force F calculated by the driving force acquisition unit 12 and the continuous average value a' of the acceleration a calculated by the acceleration acquisition unit 13. The vehicle weight m estimated by the vehicle weight estimation unit 14 is used, for example, for damping force control of a damping force adjustable suspension system. The method for estimating the vehicle weight m using the equation of motion will be described later.

[0019] Figure 2 is an operation flowchart of the vehicle weight estimation device 10 of this embodiment. According to the flowchart in Figure 2, the vehicle weight estimation device 10 first has the acceleration acquisition unit 13 calculate a continuous average value a' of acceleration a a predetermined number of times based on the acceleration a obtained by, for example, differentiating the vehicle speed V detected by a vehicle speed sensor with respect to time, and supply this to the vehicle weight estimation unit 14 (step S10).

[0020] Meanwhile, the driving force calculation unit 11 calculates the vehicle's driving force F according to the wheel torque detected by the torque sensor, for example. The driving force acquisition unit 12 then acquires the vehicle's driving force F (driving torque) calculated from the driving force calculation unit 11, calculates the continuous average value F' of the driving force for a predetermined number of times, and supplies it to the vehicle weight estimation unit 14 (step S20).

[0021] In the flowchart in Figure 2, the calculation of the continuous average value a' of acceleration a (S10) and the calculation of the continuous average value F' of driving force F (S20) are explained as being performed sequentially. However, as long as the number of calculations (a predetermined number) is the same, the order may be reversed or the calculations may be performed simultaneously.

[0022] Here, the method for calculating the driving force by the driving force calculation unit 11 will be explained. The momentum generated in the vehicle can be expressed by the equation of motion F=ma. Here, F is the force that attempts to move the vehicle in a certain direction, obtained by subtracting various driving resistance values ​​from the engine output, m is the weight of the vehicle, and a is the acceleration of the vehicle. The acceleration a can be calculated by the time derivative of the vehicle speed V.

[0023] Engine-derived power can be calculated by dividing the wheel torque by the wheel radius. Here, "wheel torque" refers to the torque generated by the drive source of a moving vehicle that acts on the wheels and accelerates or decelerates the vehicle. For example, in a vehicle driven by an internal combustion engine, wheel torque is the torque applied to the vehicle's wheels. The wheel torque of an internal combustion engine can be calculated by estimating the torque generated by the internal combustion engine from the air-fuel ratio, ambient temperature, and throttle valve opening amount, and then multiplying the resulting estimated value by the transmission loss coefficient set for each vehicle and the predetermined reduction ratio of each reduction mechanism.

[0024] On the other hand, in vehicles that have electric motors independently installed as drive sources within the wheels, the wheel torque is the sum of the torques applied to each wheel of the vehicle. The wheel torque of such a vehicle is determined by multiplying the torque estimated from the work efficiency of each motor and the voltage applied to each motor by a transmission loss coefficient set for each vehicle and a predetermined reduction ratio by each reduction mechanism. Furthermore, if the vehicle also has a differential control device (LSD) such as an electric differential, the wheel torque may be calculated by further referring to the operating status of these devices.

[0025] Figure 3 is a diagram included to illustrate the method for calculating the continuous average value used in the vehicle weight estimation device 10 of this embodiment. Using Figure 3, the method for calculating the continuous average value a' of the driving force by the driving force acquisition unit 12, or the method for calculating the continuous average value F' of the acceleration by the acceleration acquisition unit 13, will be explained below.

[0026] Figure 3 shows the relationship between the time series of actual vehicle data (i) to (iv), where the vertical axis is the driving force F or acceleration a and the horizontal axis is the time axis, and the continuous average values ​​(i)' to (iv)' obtained by smoothing the time series of actual vehicle data (i) to (iv). Here, for smoothing purposes, the continuous average values ​​were calculated by, for example, using a moving average.

[0027] As mentioned above, the momentum generated in a vehicle can be expressed as F=ma. Therefore, in Figure 3, the actual vehicle data (i) can be expressed as F1=ma1, the actual vehicle data (ii) as F2=ma2, the actual vehicle data (iii) as F3=ma3, and so on. Thus, the actual vehicle data F n This can be expressed by the following equation (1).

[0028]

number

[0029] Furthermore, the continuous mean value (i)' is F 1′ =F1=ma1=ma 1′, the continuous average value (ii)' is F2' = F1'×1 / 2 + F2×1 / 2 = m×(a1'×1 / 2 + a2×1 / 2), the continuous average value (iii)' is F3' = F2'×2 / 3 + F3×1 / 3 = m×(a2'×2 / 3 + a3×1 / 3) = ma3', ··· and can be expressed as such. Therefore, the continuous average value F n ' can be expressed by the above formula (2).

[0030] Here, let's return to the flowchart of FIG. 2 for explanation. The vehicle weight estimation unit 14 acquires the continuous average value F' of the driving force F calculated by the driving force acquisition unit 12 and the continuous average value a' of the acceleration a calculated by the acceleration acquisition unit 13, and calculates the following equation of motion (3) to estimate the weight of the vehicle (step S30).

[0031]

Equation

[0032] Here, m is the weight of the vehicle, a is the acceleration, F is the driving force, a' is the continuous average value of the acceleration, and F' is the continuous average value of the driving force F.

[0033] According to the equation of motion (3), the acceleration a acquired by the acceleration acquisition unit 13, if the number of predetermined times is n, is the acceleration a of the current (nth) time among the accelerations for the number of predetermined times n n and the continuous average value calculated by the acceleration acquisition unit 13 is the continuous average value a of the accelerations for the number of predetermined times n ' among which is the continuous average value a of the acceleration at the previous (n - 1)th time (n-1) '.

[0034] Also, the driving force acquired by the driving force acquisition unit 12, if the number of predetermined times is n, is the driving force F of the current (nth) time among the driving forces for the number of predetermined times n and the continuous average value calculated by the driving force acquisition unit 12 is the continuous average value F of the driving forces for the number of predetermined times n ' among which is the driving force F at the previous (n - 1)th time (n-1) '.

[0035] The vehicle weight estimation unit 14 estimates the vehicle weight using the equation of motion (3), and these include the acceleration a of the current (nth) time. n , the driving force F for this time (nth time) n , the continuous average value a of the acceleration immediately preceding (n-1) (n-1) ′, the continuous average value F of the driving force immediately preceding (n-1 time) (n-1) It has a built-in memory (storage unit) to store ′. In other words, the memory (storage unit 242 described later) stores the acceleration a necessary for calculating the equation of motion (3). n , driving force F n , continuous average value of acceleration a (n-1) ′, continuous average value F of the driving force (n-1) Only the ' should be kept.

[0036] (Effects of the embodiment) As described above, the vehicle weight estimation device 10 of this embodiment, which estimates the weight of a vehicle in motion, includes, for example, an acceleration acquisition unit 13 that acquires the acceleration of the vehicle and calculates the continuous average value Fn' of the acceleration Fn over a predetermined number of times, as shown in Figure 1, and an acceleration acquisition unit 13 that acquires the driving force F of the vehicle and calculates the driving force F over a predetermined number of times. n The continuous mean F n The driving force acquisition unit 12 calculates ′, and the continuous average value a of acceleration n ′ and the continuous average value F of the driving force n It includes a vehicle weight estimation unit 14 that estimates the weight of the vehicle using the equation of motion (3) from '.

[0037] Therefore, the vehicle weight estimation device 10 of this embodiment uses a large amount of memory to determine the vehicle weight from the regression line of a large number of vehicle weight estimation results, and the acceleration value a of the current (nth) time, when a predetermined number of times n is used for the calculation of the equation of motion (3), n , driving force F n , the continuous average value of the acceleration from the previous (n-1) time step a (n-1) ′, continuous average value F of the driving force (n-1) Since only the ' value needs to be stored in memory, it is possible to efficiently reduce memory usage while achieving highly accurate vehicle weight estimation.

[0038] Hereinafter, two examples of damping force adjustable suspension systems 20, in which the vehicle weight estimation device 10 according to this embodiment is applied to the damping force control of a damping force adjustable shock absorber, will be described in detail below as Example 1 and Example 2, respectively.

[0039] [Example 1] Figure 4 is a block diagram showing the functional configuration of the damping force adjustable suspension system 20 of Embodiment 1. In Figure 4, the damping force adjustable suspension system 20 of Embodiment 1 can vary the damping force of a damping force adjustable shock absorber (damper actuator), which is not shown, according to the estimated weight of the vehicle while driving. The damping force adjustable suspension system 20 of Embodiment 1 includes, as an example, a drive force calculation unit 21, a drive force acquisition unit 22, a vehicle weight estimation unit 23, a target value calculation unit 24, and a damping force control unit 25.

[0040] The driving force calculation unit 21, driving force acquisition unit 22, acceleration acquisition unit 23, and vehicle weight estimation unit 24 have the same functions as the driving force calculation unit 11, driving force acquisition unit 12, and vehicle weight estimation unit 13, respectively, which are included in the vehicle weight estimation device 10 shown in Figure 1. Therefore, to avoid duplication, the explanation of each unit is omitted.

[0041] The target value calculation unit 25 has the function of calculating a target value for damping force according to the vehicle weight estimated by the vehicle weight estimation unit 24. In addition to the vehicle weight m estimated by the vehicle weight estimation unit 24, the target value calculation unit 25 receives inputs such as the steering angle detected by the steering angle sensor installed on the vehicle, the yaw rate detected by the yaw rate sensor, the sprung mass acceleration detected by the sprung mass acceleration sensor, and the unsprung mass velocity detected by the unsprung mass acceleration sensor. The unit generates control command values ​​(target values ​​for damping force) for executing skyhook control (vibration control) for steering stability control and ride comfort control by calculation from the values ​​output by these behavior sensors and supplies them to the damping force control unit 26. Further details will be described later.

[0042] The damping force control unit 26 has the function of controlling the damping force of the damping force adjustable shock absorber according to the target value (control command value) of the damping force calculated by the target value calculation unit 25. The damping characteristics of the damping force adjustable shock absorber are controlled steplessly or stepwise between hard characteristics and soft characteristics by the current value I, which is the output of the damping force map 253.

[0043] Here, the configurations of the vehicle weight estimation unit 24 and the target value calculation unit 25 of the damping force adjustable suspension system in Example 1 will be explained using Figures 5 and 6, respectively.

[0044] Figure 5 is a block diagram showing the configuration of the vehicle weight estimation unit 24 that supplies the vehicle weight m to the target value calculation unit 25. The vehicle weight estimation unit 24 is composed of, as an example, a counting unit 241, a storage unit 242, and a weight calculation unit 243.

[0045] The counting unit 241 calculates the continuous average value a′ of acceleration and the continuous average value F′ of driving force a predetermined number of times (n). cnt This is a counter that counts the acceleration a. The memory unit 242 counts the acceleration a acquired this time (nth time), where n is the number of calculations (estimation) performed according to the equation of motion (3). n and driving force F n , and the continuous average value a of the acceleration calculated (estimated) immediately before (n-1 times) (n-1) ′ and the continuous average value F of the driving force (n-1) A register is a way to store '.

[0046] The weight calculation unit 243 retrieves from the memory unit 242 the acceleration a of the current (nth) operation, where n is the number of operations (estimations) required to calculate (estimate) the equation of motion (3). n and driving force F n , and the continuous average value a of the acceleration calculated immediately before (n-1 times) (n-1) ′ and the continuous average value F of the driving force (n-1) The system reads out ' and performs calculations to estimate the vehicle weight m, which is then output to the target value calculation unit 25.

[0047] The vehicle weight estimation unit 24 may further include a reliability setting unit 244. The reliability setting unit 244 determines the acceleration a for the current (nth) time. n And set the confidence level for the true value of the driving force F, and the weighting coefficient K. a ,K F The respective values ​​are calculated and supplied to the weight calculation unit 243. The reliability setting unit 244 verifies the reliability of the acceleration and driving force for the current (nth) time, and if the reliability is high, the weight coefficient K is calculated accordingly. a ,K F By setting this value higher and reflecting it in the vehicle weight estimation, the accuracy of the vehicle weight estimation by the weight calculation unit 243 can be further improved.

[0048] Figure 6 is a block diagram showing the configuration of the target value calculation unit 25. As shown in Figure 6, the target value calculation unit 25 is composed of, for example, a skyhook control unit 251, a multiplier 252, a damping force map 253, and an integration unit 254.

[0049] The Skyhook Control Unit 251 calculates a control command value C1 for executing steering stability control based on the vehicle's behavior, and generates a control command value C2 for executing Skyhook control. The Skyhook Control Unit 251 converts the respective control command values ​​C1 and C2 for steering stability control and ride comfort control into a control command value C3 corresponding to the target damping force (Skyhook control amount) and supplies it to the Multiplier 252.

[0050] The multiplier 252 is also supplied with the vehicle weight m, calculated (estimated) by the vehicle weight estimation unit 24 (weight calculation unit 243 in Figure 5) using the above-mentioned equation of motion (3), as a correction value for the target damping force (control command value C4). The control command value C4 is multiplied by the control command value C3 corresponding to the target damping force by the multiplier 252, and converted into a control command value C5 corresponding to the target damping force that takes into account the change in vehicle weight (sprung mass). The converted control command value C5 is then supplied to the damping force map 253.

[0051] The damping force map 253 correlates the control command value C5 with the current value I supplied to the damping force adjustable shock absorber (damper actuator) to the relative speed (piston speed of the damping force adjustable shock absorber), and was created in advance based on test data from the inventors.

[0052] (Operation of Example 1) Figure 7 is a flowchart showing the basic processing operation of the damping force adjustable suspension device 20 of Example 1, Figure 8 is a flowchart showing the detailed procedure of the weight estimation process of Example 1, and Figure 9 is a flowchart showing the detailed procedure of the damping force target value calculation process of Example 1.

[0053] The operation of the damping force adjustable suspension device 20 of Embodiment 1 shown in Figures 4 to 6 will be described in detail below, with reference to the flowcharts in Figures 7 to 9.

[0054] In Figure 7, the damping force adjustable suspension system 20 of Embodiment 1 first uses a drive force calculation unit 21 and an acceleration acquisition unit 23 to acquire vehicle state quantities detected by behavior sensors mounted on the vehicle (step S100). The drive force calculation unit 21 acquires, for example, wheel torque detected by a torque sensor, and the acceleration acquisition unit 23 acquires vehicle speed detected by a vehicle speed sensor. The torque sensor and vehicle speed sensor are sensors mainly used for controlling the driving, steering, and braking of the vehicle.

[0055] Next, the driving force calculation unit 21 calculates the vehicle's driving force F (torque) using the equation of motion F=ma as described above, and supplies it to the driving force acquisition unit 22 (step S200). The driving force acquisition unit 22 then calculates the continuous average value F' of the driving force, and the acceleration acquisition unit 23 calculates the continuous average value a' of the acceleration (step S300). The driving force acquisition unit 22 and the acceleration acquisition unit 23 then output the calculated continuous average value F' of the driving force and the continuous average value a' of the acceleration to the vehicle weight estimation unit 24. The process up to this point overlaps with the flowchart in Figure 2, so a detailed explanation is omitted to avoid duplication.

[0056] (Vehicle weight estimation process) When the vehicle weight estimation unit 24 performs the vehicle weight estimation process (step S400), the vehicle weight estimation (calculation) is performed a predetermined number of times (for example, 500 times) at predetermined intervals (for example, 20ms). Therefore, as shown in the flowchart of Figure 8, first, an initial setup process is performed (step S401) in which the counter (counting unit 241) is set to "0", the contents of registers A and B (storage unit 242) are cleared, and the timer is started.

[0057] Here, the counter is used to count the vehicle weight estimation a predetermined number of times (n=500). Register A is used to sequentially hold the continuous average value F' of the driving force F, and register B is used to sequentially hold the continuous average value a' of the acceleration a. Here, "sequentially hold" means that the current estimation result overwrites the previous estimation result. The timer times out after 20ms.

[0058] Next, the weight calculation unit 243 updates the estimated number n indicated by the counter (+1) (step S402), and then the driving force F calculated by the driving force calculation unit 21 and acquired by the driving force acquisition unit 22 is obtained. n The acceleration a acquired by the acceleration acquisition unit 23 is obtained along with the acceleration a n The weight calculation unit 243 then stores the continuous average value F1' of the driving force calculated by the driving force acquisition unit 22 in register A, and the continuous average value a1' of the acceleration calculated by the acceleration acquisition unit 23 in register B (step S404).

[0059] The processes described in steps S402 to S404 are repeated n (500) times (the processes S402 to S404 are looped in step S405 "NO"), and each time the contents of registers A and B are updated (continuous average value of driving force F1' → F2' → F3' → ... → F n ′, continuous average value of acceleration a1′→a2′→a3′→···→a n ′).

[0060] Next, when the weight calculation unit 243 determines that the counter has counted a predetermined number of times (n=500) (step S405 "YES"), it calculates the driving force F for the current n (500th time), where n is the number of calculations (estimates) required to calculate the above-mentioned equation of motion (3). n The acceleration a of n (500th time) is obtained from the driving force acquisition unit 22. n The acceleration is acquired from the acceleration acquisition unit 23. At the same time, the continuous average value F of the driving force from the previous n-1 (499th) time is obtained from register A. (n-1) Read ' from register A and calculate the continuous average value a of the acceleration from the previous n-1 (499th) measurement. (n-1) Read ' from register B (step S406).

[0061] Then, the weight calculation unit 243 performs calculations for estimating the vehicle's weight using the equation of motion (3) described above (step S407). Here, the data item necessary for estimating the vehicle's weight is the acceleration a for the current (nth) time. n And the driving force F for this time (nth time) n , and the continuous average value a of the acceleration from the previous (n-1) time. (n-1) ′ and the continuous average value F of the driving force from the previous (n-1) time. (n-1) This is the only case. Therefore, in Example 1, it is only necessary to store the four data items required for the calculation (estimation) of the equation of motion (3) described above in memory (storage unit 242), thus efficiently reducing the amount of memory (storage unit) used while achieving highly accurate vehicle weight estimation through calculation.

[0062] The weight calculation unit 243 uses the weight coefficient K set by the reliability setting unit 244. F ,K a By using this, the accuracy of vehicle weight estimation can be further improved. Here, K F K is the weighting coefficient for the driving force. a This is the weighting coefficient for acceleration.

[0063] In other words, the reliability setting unit 244 sets the reliability of the true values ​​of acceleration a and driving force F in the current (nth) time, and the weighting coefficient K F ,K aThe respective values ​​can be calculated and supplied to the weight calculation unit 243. The reliability setting unit 244 verifies the reliability of the acceleration and driving force for the current (nth) time, and if the reliability is high, the weight coefficient K can be adjusted accordingly. F ,K a The settings are adjusted to increase each of these parameters, and this is reflected in the vehicle weight estimation.

[0064] At this time, the weight calculation unit 243 (vehicle weight estimation unit 24) performs calculations for estimating the vehicle weight using the following equation of motion (4), and outputs the estimated vehicle weight to the target value calculation unit 25.

[0065]

number

[0066] However, m is the vehicle weight, a is acceleration, F is the driving force, a' is the continuous average value of acceleration, F' is the continuous average value of driving force, K a K is the weighting coefficient for acceleration. F is a weighting coefficient for the driving force. In Example 1, a counter was used to acquire acceleration a and driving force F data for a predetermined number of times (e.g., 500 times) at predetermined cycles (e.g., 20 m seconds), and the system was configured to calculate the continuous average value a' of acceleration and the continuous average value F' of driving force. However, without setting a predetermined number of times (e.g., 500 times) as an upper limit, the system may be configured to acquire acceleration a and driving force F data for a cumulative number of times less than the predetermined number, and to calculate the continuous average value a' of acceleration and the continuous average value F' of driving force. In this case, in step S405 of the flowchart in Figure 8, instead of determining whether the predetermined number of times n exceeds 500, it is determined, for example, whether the reduction ratio (gear ratio) of the transmission of the vehicle has fallen below a predetermined value, and if it falls below the predetermined value, the system proceeds to the process from step S406 onwards.

[0067] (Target value calculation process) Next, the process of calculating the target value of the damping force by the target value calculation unit 25 (step S500 in Figure 7) will be explained in detail with reference to the configuration diagram of the target value calculation unit 25 shown in Figure 6 and the flowchart showing its detailed procedure in Figure 9.

[0068] In Figure 9, the target value calculation unit 25 first obtains the vehicle's behavior (state information) from various signals detected by behavior sensors installed on the vehicle (step S510) via the skyhook control unit 251. For example, this includes the steering angle detected by the steering angle sensor and the yaw rate detected by the yaw rate sensor. Then, it calculates a control command value C1 for executing steering stability control from this vehicle behavior. It also calculates the sprung velocity by integrating the sprung acceleration detected by the sprung acceleration sensor and calculates a control command value C2 for executing vibration damping control (ride comfort control) such as skyhook based on this sprung acceleration (step S520). The steering angle sensor, yaw rate sensor, and sprung acceleration sensor are sensors mainly used for controlling the braking, driving, and steering of the vehicle.

[0069] Next, the Skyhook Control Unit 251 converts the respective control command values ​​C1 and C2 for steering stability control and ride comfort control into a control command value C3 corresponding to the target damping force (Skyhook control amount) and supplies it to the multiplier 252 (step S530). In addition, the vehicle weight m of the vehicle, estimated from the vehicle weight estimation unit 24 (weight calculation unit 243) using the above-mentioned equation of motion (3 or 4), is calculated as a control command value C4 for correction and supplied to the multiplier 252 (step S540). The control command value C4 is multiplied by the control command value C3 corresponding to the target damping force by the multiplier 252 to convert it into a control command value C5 corresponding to the (corrected) target damping force that takes into account the change in vehicle weight (sprung mass), and the converted control command value C5 is supplied to the damping force map 253 (step S550).

[0070] The damping force map 253 stores the correlation between the target damping force (control command value C5) and the current value I supplied to the damping force adjustable shock absorber (actuator), associating this with the relative speed (piston speed of the damping force adjustable shock absorber). Here, the relative speed between the sprung mass and the unsprung mass is calculated by integrating the detection signals from the sprung mass acceleration sensor and the unsprung mass acceleration sensor in the integration unit 254. Based on this relative speed between the sprung mass and the unsprung mass, the damping force map 253 is referenced, and the control command value I, which is the target value of the damping force of the damping force adjustable shock absorber, is output from the target value calculation unit 25 (step S560).

[0071] Returning to the explanation in Figure 7, the damping force control unit 26, having obtained the control command value I by current from the target value calculation unit 25, controls the damping characteristics of the damping force adjustable shock absorber (damper actuator) so that they change continuously or in steps between hard characteristics and soft characteristics (step S600).

[0072] (Effects of Example 1) As described above, the damping force adjustable suspension system 20 of Embodiment 1 varies the damping force of the damping force adjustable shock absorber according to the estimated weight of the vehicle in motion. For example, as shown in Figure 4, it includes a vehicle weight estimation unit 24 that estimates the weight of the vehicle, a target value calculation unit 25 that calculates a target value for the damping force according to the vehicle weight estimated by the vehicle weight estimation unit 24, and a damping force control unit 26 that controls the damping force of the damping force adjustable shock absorber according to the target value. The vehicle weight estimation unit 24 includes an acceleration acquisition unit 23 that acquires the acceleration of the vehicle and calculates the continuous average value of the acceleration for a predetermined number of times, a driving force acquisition unit 22 that acquires the driving force of the vehicle and calculates the continuous average value of the driving force for a predetermined number of times, and a vehicle weight estimation unit 24 that estimates the weight of the vehicle using the equation of motion from the continuous average value of the acceleration and the continuous average value of the driving force.

[0073] Here, the vehicle weight estimation unit 24 further includes, for example, as shown in Figure 5, a counter (counting unit 241) that counts the current count out of a predetermined number of counts, and a storage unit 242 that stores the continuous average value a' of the acceleration at the (n-1)th time and the continuous average value F' of the driving force, when the current count is n. The weight calculation unit 243 then performs calculations for estimating the vehicle weight a predetermined number of times at predetermined cycles using the equation of motion (3) described above. Here, the data items necessary for estimating the vehicle weight are, when the number of calculations (estimations) is n, the acceleration a obtained this time (nth time). n and driving force F n , and the continuous average value a of the acceleration calculated immediately before (n-1 times) (n-1) ′ and the continuous average value F of the driving force (n-1) It is only '.

[0074] According to the damping force adjustable suspension system 20 of Example 1, the vehicle weight estimation unit 24 calculates a target value for the damping force according to the estimated vehicle weight, and the damping force of the damping force adjustable shock absorber can be controlled according to the target value. In particular, when the vehicle weight estimation unit 24 estimates the vehicle weight, the acceleration value a obtained this time (nth time) is necessary for the n calculations (estimation) using the equation of motion (3) described above. n , driving force F n , and the continuous average value a of the acceleration calculated immediately before (n-1 times) (n-1) ′, continuous average value F of the driving force (n-1) Only the value of ' needs to be stored in memory (storage unit 242). Therefore, the amount of memory (storage unit 242) used can be efficiently reduced while achieving highly accurate vehicle weight estimation by calculation (estimation). For this reason, the target value calculation unit 25 can calculate a highly accurate target value of damping force according to the vehicle weight estimated by the vehicle weight estimation unit 24, and the damping force control unit 26 controls the damping force of the damping force adjustable shock absorber according to this target value, thereby providing a highly responsive damping force adjustable suspension system 20.

[0075] Furthermore, the damping force adjustable suspension system 20 of Embodiment 1 may also have a reliability setting unit 244 that sets the reliability of the true values ​​of acceleration and driving force at the nth time and calculates weighting coefficients for each. In this case, the equation of motion used by the vehicle weight estimation unit 24 for estimating the vehicle weight is equation (4) described above, and in addition to the continuous average value a' of acceleration a and the continuous average value F' of driving force F, a weighting coefficient K for acceleration a is also used. a , weighting coefficient K for the driving force F F The following is used. The reliability setting unit 244 verifies the reliability of the acceleration and driving force in this case (n), and if the reliability is high, the weighting coefficient K is used accordingly. a ,K F By setting the value to be higher and reflecting this in the vehicle weight estimation by the vehicle weight estimation unit 24, the accuracy of the vehicle weight estimation can be further improved. Therefore, the target value calculation unit 25 can calculate a highly accurate target value of damping force according to the vehicle weight estimated by the vehicle weight estimation unit 24, and the damping force control unit 26 controls the damping force of the damping force adjustable shock absorber according to this target value, thereby providing a damping force adjustable suspension system with better responsiveness.

[0076] [Example 2] The damping force adjustable suspension system 20 of Example 1 calculates the total weight of the vehicle based on the vehicle's acceleration scenario, and does not take into account the road surface inclination, or the fine damping force in the case of uneven loading when there are occupants or cargo. The damping force adjustable suspension system 20 of Example 2, described below, has an estimation function that reflects the distribution of vehicle weight due to the effect of loading in determining the target damping force.

[0077] The damping force adjustable suspension system 20 of Example 2 will be described in detail below using Figures 10 to 13. Figure 10 is a diagram showing an estimated image of the front and rear load distribution of the vehicle, Figure 11 is a configuration diagram of the target value calculation unit 25 of the damping force adjustable suspension system 20 of Example 2, and Figure 12 is a flowchart showing the detailed procedure of the target value calculation process (weight distribution estimation process) performed by the target value calculation unit 25 of Example 2.

[0078] First, we will explain the estimation of vehicle weight distribution based on load effects using the estimated image of the vehicle's front-rear load distribution shown in Figure 10. When controlling the vehicle's driving state, a front-rear G sensor 340 that detects the vehicle's front-rear G-force is generally used. Here, we assume that the front-rear G sensor 340 is located approximately in the center of the vehicle, as shown in Figure 10, and θ rd θ is the angle of inclination of the road surface. ph This indicates the pitch angle at which the sensor coordinates are tilted relative to the road surface coordinates.

[0079] According to Figure 10, component G is located in the sensor coordinates. x The component G in the sensor coordinates of gravity can be expressed by the following equation (5), where G is the component in the sensor coordinates of gravity. grade This can be expressed by the following equation (6). Here, the component of gravity in the sensor coordinates (measured value G from the front and rear G sensors) sens ) is the sum of the sensor coordinate components of acceleration parallel to the road surface and acceleration due to gravity (G sens =G x +G grade Since this is the case, it can be expressed by the following equations (7) and (8).

[0080]

number

[0081] In other words, the measurement value of the front and rear G sensors 340 is the pitch angle θ of the vehicle body, which is the time derivative of the vehicle speed V. ph And the road surface inclination angle θ rd and the pitch angle θ of the vehicle body ph This is the gravitational acceleration component of the sum of the values. Here, dV / dt is the time derivative of the vehicle speed V, and θ is the slope angle of the road surface. rd Since this value constantly changes while the vehicle is in motion, it can be obtained as a value close to 0 by integrating according to the following equation (9), but the measured value G from the front and rear G sensors sens and pitch angle θ ph This can increase or decrease depending on the load.

[0082]

number

[0083] The damping force adjustment type suspension device 20 of Example 2 basically has the same configuration as the damping force adjustment type suspension device 20 of Example 1 shown in FIG. 4, and only the configuration of the target value calculation unit 25 is different. Hereinafter, the description will be made focusing on the target value calculation unit 25 shown in FIG. 11.

[0084] As shown in FIG. 11, which shows the configuration of the target value calculation unit 25 in the damping force adjustment type suspension device 20 of Example 2, the target value calculation unit 25 has a partial load detection unit 255 that calculates the degree of partial load, which is the bias of the weights applied to each of the plurality of wheels of the vehicle, and has a function of calculating the target value of the damping force using the degree of partial load calculated by the partial load detection unit 255.

[0085] The partial load detection unit 255 calculates the degree of partial load in the pitch direction of the vehicle according to the differential value of the vehicle speed V and the longitudinal G, and calculates the degree of partial load in the roll direction of the vehicle according to the lateral acceleration (lateral G) of the vehicle. Since the other configurations are the same as those of the target value calculation unit 25 of the damping force adjustment type suspension device 20 of Example 1 shown in FIG. 6, the description will be omitted to avoid duplication.

[0086] Here, the "degree of partial load in the pitch direction" means the degree of partial load in the front and rear wheels (two wheels), and the "degree of partial load in the roll direction" means the degree of partial load in the left and right wheels (two wheels). Also, the "degree of partial load" means the weight distribution of the loads applied to the front, rear, left, and right wheels due to the loading effect. Here, it refers to the "wheel load ratio" represented by the load applied to each of the front, rear, left, and right wheels / the total weight of the vehicle (m total ). Specifically, for the front wheels, it is m fronto / m total , for the rear wheels, it is m rear / m total , for the left wheels, it is m left / m total , for the right wheels, it is m right , / m total .

[0087] As shown in Figure 12, the flowchart illustrates the procedure for calculating the target value of the damping force adjustable suspension system 20 of Embodiment 2 (vehicle weight distribution estimation process performed by the uneven load detection unit 255). First, the target value calculation unit 25 has the skyhook control unit 251 acquire behavior information, which is the state information of the vehicle, from signals detected by behavior sensors installed on the vehicle (step S510). For example, this could be the steering angle detected by the steering angle sensor, the yaw rate detected by the yaw rate sensor, etc.

[0088] The Skyhook Control Unit 251 calculates a control command value C1 for executing steering stability control from the acquired vehicle behavior, and also calculates a control command value C2 for executing Skyhook control based on the sprung mass acceleration detected by the sprung mass acceleration sensor, which is then integrated to obtain the sprung mass velocity (step S520). Subsequently, the Skyhook Control Unit 251 converts the respective control command values ​​C1 and C2 for steering stability control and ride comfort control into a control command value C3 corresponding to the target damping force (Skyhook control amount) and supplies it to the multiplier 252 (step S530).

[0089] Meanwhile, the uneven load detection unit 255 uses the above-mentioned equation (9) to estimate the pitch state of the vehicle according to the derivative of the vehicle speed V and the longitudinal G, and also estimates the roll state of the vehicle according to the lateral G of the vehicle (step S541). Subsequently, the uneven load detection unit 255 calculates the total vehicle weight m estimated by the vehicle weight estimation device 10 (vehicle weight estimation unit 24). total By obtaining this data and using the previously estimated pitch and roll states of the vehicle, the degree of uneven loading (=wheel load ratio α) m, which is expressed as wheel load / total vehicle weight, is calculated for each of the front, rear, left, and right wheels. fronto / m total ,m rear / m total ,m right ,m left / m total We estimate (step S542).

[0090] Furthermore, the pitch or roll state of the vehicle can be determined not by equation (9) above, but by, for example, detecting the pitch angular velocity and roll angular velocity as the vehicle's motion state using an IMU (Integrated Measurement Unit) sensor installed on the vehicle, and integrating these angular velocities to obtain the pitch angle and roll angle.

[0091] Here, wheel load can be considered as a result of load transfer in the front, rear, left, and right directions due to road surface inclination, front and rear load transfer during vehicle braking, left and right load transfer during cornering, or static load changes due to occupants and cargo. The estimated wheel load ratio α corresponding to these load transfers is obtained by referring to a weight-dependent model (map) that allows setting an appropriate damping force for each wheel based on the wheel load, and a correction control command value C is used to determine the appropriate target damping force for each wheel. α This is calculated and supplied to the multiplier 252 (step S543). The weight-dependent model associates the vehicle's pitch and roll states with the wheel load ratio and was created in advance based on test data by the inventors.

[0092] In addition, the wheel load ratio α can also be estimated using methods based on vehicle specifications such as the vehicle's center of gravity, vehicle volume, and inertia, or by calculation using values ​​measured with vehicle behavior, as will be described later.

[0093] Correction control command value C α This is multiplied by the control command value C3 output from the skyhook control unit 251 (multiplier 252) to convert it into a control command value C5 corresponding to the target damping force of the wheel, taking weight distribution into consideration, and the converted control command value C5 is supplied to the damping force map 253 (step S550).

[0094] The damping force map 253 correlates the control command value C5 with the current value I supplied to the damping force adjustable shock absorber (actuator), and maps this correlation to the relative velocity between the sprung mass and the unsprung mass (piston speed of the damping force adjustable shock absorber). Here, the relative velocity between the sprung mass and the unsprung mass is calculated by integrating the detection signals from the sprung mass acceleration sensor and the unsprung mass acceleration sensor using the integration unit 254. Based on this relative velocity between the sprung mass and the unsprung mass, the damping force map 253 is referenced, and the current value I, which is the target value of the damping force of the damping force adjustable shock absorber, is used. f ,I re ,I ri ,I le This is output for each wheel (step S560).

[0095] Furthermore, the degree of uneven load distribution (wheel load ratio α) can be determined from the wheel speed, rather than relying on the weight-dependent model described above. The detection signal from the wheel speed sensor contains components of the tire's vibration frequency, and by performing frequency analysis on this detection signal, the resonant frequency for each wheel can be obtained. Typically, vehicles equipped with ABS (Anti-lock Brake System) or brake assist systems have wheel speed sensors on each wheel, so there is no need to add any new sensors when detecting the resonant frequency of the tires.

[0096] When the wheel load changes due to load transfer or other factors, the power spectrum of the resonant frequency changes. Specifically, the power spectrum value of the resonant frequency of a wheel decreases as the wheel load decreases, and increases as the wheel load increases as the power spectrum of the wheel's resonant frequency increases.

[0097] At this time, the uneven load detection unit 255, for example, calculates and stores the standard power spectrum value when there is no load effect, and when it detects an event in which the wheel load changes, it calculates the difference between this value and the power spectrum value calculated, and by referring to a map that shows the relationship between this difference and the wheel load ratio, it calculates the wheel load ratio m fronto / m total ,m rear / m total ,m left / m total, m right / m totalIt is possible to obtain it.

[0098] Wheel load ratio m for each wheel calculated by the uneven load detection unit 255 fronto / m total ,m rear / m total ,m left / m total, m right / m total This is supplied to the multiplier 252. The multiplier 252 is also supplied with a control command value corresponding to the skyhook control amount C3 calculated by the skyhook control unit 251, and this control command value is used to obtain the wheel load ratio α(m) for each wheel. fronto / m total ,m rear / m total ,m left / m total ,m right / m total By multiplying these values ​​as correction command values ​​for the skyhook control amount, the target damping force m for each wheel, which reflects the change in wheel load, is obtained. fronto ,m rear ,m right ,m left It is converted and output to damping force map 253.

[0099] The damping force map 253 includes the target damping force (control command value C5) for each wheel and the current value I supplied to the damping force adjustable shock absorber (actuator) provided for each wheel. f ,I re ,I ri ,I le This correlation is mapped to the relative speed (piston speed of the damping force adjustable shock absorber). Here, the relative speed between the sprung mass and the unsprung mass is calculated by integrating the detection signals from the sprung mass acceleration sensor and the unsprung mass acceleration sensor in the integration unit 254. Based on this relative speed between the sprung mass and the unsprung mass, the damping force map 253 is referenced, and the current value I for each wheel, which is the target value of the damping force of the damping force adjustable shock absorber, is determined. f ,I re ,I ri ,I le The following will be output.

[0100] The current value I for each wheel corresponding to the control command value C5 is calculated from the target value calculation unit 25. f ,I re ,I ri ,I le The damping force control unit 26, having obtained the necessary information, controls the damping force adjustable shock absorber (damper actuator) so that its damping characteristics change continuously or in steps between hard and soft characteristics.

[0101] (Effects of Example 2) As described above, according to the damping force adjustable suspension device 20 of Embodiment 2, the target value calculation unit 25 has an uneven load detection unit 255 (Figure 11) that calculates the uneven load, which is the weight distribution on each of the multiple wheels of the vehicle, and calculates the target value of the damping force using the uneven load calculation unit 255. In addition, the uneven load detection unit 255 calculates the uneven load in the pitch direction of the vehicle according to the differential value of the vehicle's body speed and the acceleration in the longitudinal direction, and calculates the uneven load in the roll direction of the vehicle according to the acceleration in the lateral direction of the vehicle.

[0102] Conventionally, load detection weight estimation has only estimated the total vehicle weight for vehicle acceleration scenes and calculated the target damping force. However, with the damping force adjustable suspension device 20 of Example 2, it is possible to calculate the target damping force by estimating the vehicle weight distribution due to load transfer in the front, rear, left, and right directions caused by road surface inclination, front and rear load transfer during vehicle braking, left and right load transfer during cornering, or static load changes due to occupants and cargo, thereby enabling appropriate damping force adjustment for each wheel and highly accurate damping force control.

[0103] (Configuration of a vehicle with a damping force adjustable suspension system) Figure 13 is a schematic diagram showing an example of the configuration of a vehicle having a damping force adjustable suspension system 20 according to Example 1 or Example 2. As shown in Figure 13, the vehicle 900 comprises a suspension system 150, a body 200, wheels 300, an engine 500, and an ECU (Electronic Control Unit) 600.

[0104] The letters A through E in the code represent the position on vehicle 900, respectively. A represents the front left position of vehicle 900, B represents the front right position of vehicle 900, C represents the rear left position of vehicle 900, D represents the rear right position of vehicle 900, and E represents the rear of vehicle 900.

[0105] Vehicle 900 is equipped with a vehicle speed sensor 540, a longitudinal G sensor 340, a lateral G sensor 350, a wheel torque sensor 510, a wheel speed sensor 360, and a steering angle sensor 460, among others. These sensors are behavior sensors that sense the state (behavior) of vehicle 900 and are commonly installed in vehicle 900. More specifically, they are sensors mainly used for controlling the braking, driving, and steering of vehicle 900.

[0106] The vehicle speed sensor 540 is installed, for example, on the output shaft of the transmission mounted on the vehicle 900. The vehicle speed sensor 540 detects the vehicle speed, which is the speed of the vehicle 900 (vehicle body 200).

[0107] Furthermore, the longitudinal G sensor 340 and the lateral G sensor 350 are installed, for example, on the vehicle body 200 which is the sprung mass of the vehicle 900. The longitudinal G sensor 340 detects the longitudinal acceleration of the vehicle 900 (vehicle body 200) (the "Gsens" mentioned above), and the lateral G sensor 350 detects the lateral acceleration of the vehicle 900 (vehicle body 200) (lateral G).

[0108] The wheel torque sensor 510 estimates the torque (wheel torque) generated by the engine 500. Here, the wheel torque is the torque applied to the wheels of the vehicle 900, as described above, and corresponds to the driving force of the vehicle 900.

[0109] The wheel speed sensors 360 are provided for each wheel and detect the rotational speed of each wheel. Alternatively, the vehicle speed sensor 540 may be omitted, and the vehicle speed may be obtained from the wheel speeds of the wheel speed sensors 360.

[0110] The steering angle sensor 460 is installed, for example, on the steering wheel of the vehicle 900. The steering angle sensor 460 detects the steering angle (rotation angle) or wheel steering angle generated by the steering operation of the driver operating the vehicle 900.

[0111] Vehicle 900 may also be equipped with additional sprung mass acceleration sensors, unsprung mass acceleration sensors, and IMU sensors, which are not shown in the figures. The IMU sensor can detect longitudinal acceleration in addition to roll angular velocity and pitch angular velocity as part of the vehicle 900's motion state. The roll angular velocity and pitch angular velocity detected by the IMU sensor may be used to estimate the pitch state and roll state as described above.

[0112] The output values ​​of these behavior sensors are supplied to the ECU 600, and control signals are transmitted from the ECU 600 to each component via the CAN (Controller Area Network) 370. While the aforementioned behavior sensors may be newly installed for the purpose of estimating vehicle state variables, it is preferable, from a cost perspective, to use existing sensors in the vehicle 900.

[0113] The suspension system 150 includes, for example, an absorber interposed between the vehicle body and the wheels, and a spring arranged to expand and contract with the stroke of the absorber. The absorber includes a cylinder, a piston that divides the inside of the cylinder into two chambers and is slidable, a piston rod fixed to the piston, a connecting passage that connects the two chambers, and a solenoid valve that can open and close the connecting passage. Both chambers separated by the piston are filled with hydraulic fluid. The spring is arranged to surround the outer circumference of the piston rod and is supported at the end of the cylinder and the end of the piston rod. The ECU 600 adjusts the opening of the solenoid valve according to the estimated vehicle weight, so that the damping force of the suspension system 150 increases as the estimated vehicle weight increases.

[0114] The structure of the suspension system 150 is not limited. For example, the position of the solenoid in the suspension system 150 is not limited. The suspension system 150 may be, for example, a piston-in type or an outer cylinder connection type. Furthermore, the type of suspension system 150 is not particularly limited; for example, it may be a strut type or a double wishbone type. Thus, various structures or types of suspension systems can be used for the suspension system 150. Also, the method for adjusting the damping force in the suspension system 150 is not limited; it may be a method of adjusting the damping force in the absorber as described above, or a method of varying the spring rate of the spring (automatic variable preload), or both.

[0115] [Examples of implementation using software] The component blocks of the vehicle weight estimation device 10 in this embodiment and the component blocks of the damping force adjustable suspension device 20 in Examples 1 and 2 may be implemented by logic circuits (hardware) formed on an integrated circuit (IC chip) or the like, or by software.

[0116] Each system includes a computer that executes instructions for a program, which is software that implements each function. This computer includes, for example, one or more processors and a computer-readable recording medium that stores the program. The objective of the present invention is achieved when the processor reads the program from the recording medium and executes it in the computer. For example, a CPU (Central Processing Unit) can be used as the processor. As the recording medium, a "tangible medium that is not temporary," such as ROM (Read Only Memory), can be used, as well as tape, disk, card, semiconductor memory, programmable logic circuit, etc. It may also further include RAM (Random Access Memory) for deploying the program. Furthermore, the program may be supplied to the computer via any transmission medium capable of transmitting the program (such as a communication network or broadcast waves). In one aspect of the present invention, the program can also be realized in the form of a data signal embedded in a carrier wave, which is embodied by electronic transmission.

[0117] The present invention is not limited to the exemplary embodiments described above, and those skilled in the art will be able to easily modify the exemplary embodiments described above to the extent included in the claims. [Explanation of symbols]

[0118] 10... Vehicle weight estimation device, 11, 21... Drive force calculation unit, 12, 22... Drive force acquisition unit, 13, 23... Acceleration acquisition unit, 14, 24... Vehicle weight estimation unit, 20... Damping force adjustable suspension system, 25... Target value calculation unit, 26... Damping force control unit, 150... Suspension system, 200... Vehicle body, 241... Counting unit, 242... Memory unit, 243... Weight calculation unit, 244... Reliability setting unit, 2 51...Skyhook control unit, 252...Multiplier, 253...Damping force map, 254...Integrator, 255...Uneven load detection unit, 300...Wheels, 340...Front / rear G sensors, 350...Lateral G sensors, 360...Wheel speed sensors, 460...Steering angle sensors, 500...Engine, 510...Wheel torque sensors, 540...Vehicle speed sensors, 600...ECU, 900...Vehicle.

Claims

1. A vehicle weight estimation device for estimating the weight of a vehicle in motion, An acceleration acquisition unit that acquires the acceleration of the vehicle at predetermined intervals and calculates the continuous average value of the acceleration for a predetermined number of times or a cumulative number of times, A driving force acquisition unit acquires the driving force of the vehicle at predetermined intervals and calculates the continuous average value of the driving force for a predetermined number of times or a cumulative number of times. It includes a vehicle weight estimation unit that estimates the weight of the vehicle using an equation of motion from the continuous average value of the acceleration and the continuous average value of the driving force, The vehicle weight estimation unit is, A counter that counts the current number of times or the cumulative number of times relative to the predetermined number of times, The system further includes a storage unit that stores only the continuous average value of the acceleration and the continuous average value of the driving force at the (n-1)th time, when the current number of times is defined as n times. The aforementioned equation of motion is, A vehicle weight estimation device that satisfies the following equation (3). [Math 1] However, m is the vehicle weight, a is acceleration, F is the driving force, a' is the continuous average value of acceleration, and F' is the continuous average value of driving force.

2. The vehicle weight estimation unit is, The system further includes a reliability setting unit that sets the reliability of the true values ​​of the acceleration and the driving force in the nth trial and calculates weighting coefficients for each. The aforementioned equation of motion is, A vehicle weight estimation device according to claim 1 that satisfies the following formula (4). [Math 2] However, m is the vehicle weight, a is acceleration, F is the driving force, a' is the continuous average value of acceleration, F' is the continuous average value of driving force, Ka is the weighting coefficient for acceleration, and KF is the weighting coefficient for driving force.

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