Vehicle weight estimating device and method for same

Abstract

A vehicle weight estimating device (10A) for estimating the weight of a vehicle having fitted wheels comprises: a vehicle weight estimating unit (11) for estimating the weight of the vehicle using a physical quantity including the acceleration of the vehicle as a component; a wheel diameter calculating unit (12) for calculating a dynamic load radius of the wheels using a physical quantity including the speed of the vehicle as a component; and a vehicle weight updating unit (13) for acquiring the acceleration of the vehicle and the speed of the vehicle at different times and updating the weight of the vehicle estimated using the dynamic load radius.

Description

Vehicle weight estimation device and method

[0001] The present invention relates to a vehicle weight estimation device that estimates the weight of a vehicle having wheels attached thereto.

[0002] For example, Patent Document 1 describes a technology relating to a tire wheel load estimation method that can accurately and inexpensively calculate the wheel load of each wheel of a vehicle. According to the technology described in Patent Document 1, in the process of calculating the vehicle mass (weight), assuming that the vehicle is traveling on a road surface with a tilt angle θ, the vehicle mass (weight) can be calculated by m(α+g sin(θ))+AV2=T / R, where m is the mass of the vehicle, V is the vehicle speed, α is the vehicle acceleration, T is the total axle shaft torque of the vehicle, R is the tire-loaded radius (dynamic load radius), θ is the tilt angle of the road surface, A is the aerodynamic resistance, and g is the gravitational acceleration (see paragraph

[0009] ).

[0003] JP 2010-76703 A

[0004] Incidentally, it is known that sensor noise is a major factor in causing errors in estimating vehicle weight. Therefore, it is preferable that state quantities including vehicle acceleration and vehicle speed have as large values ​​as possible so as to relatively reduce sensor noise. However, according to general control, including the technology described in Patent Document 1, vehicle state quantities including acceleration and vehicle speed are acquired at the same time, or one is acquired and the other is calculated. Thus, if acceleration and vehicle speed are acquired at the same time, for example, when the vehicle starts, acceleration is high but vehicle speed is low, and after a while has passed since the start, vehicle speed is high but acceleration decreases, which contradicts the idea of ​​acquiring large values ​​for both to relatively reduce sensor noise.

[0005] The present invention has been made to solve the above-mentioned problems, and aims to provide a vehicle weight estimation device, etc., which reduces errors contained in the vehicle weight estimation results and improves the accuracy of vehicle weight estimation by adjusting the timing of acquiring vehicle state quantities including vehicle acceleration and vehicle speed.

[0006] Other objects of the present invention will become apparent to those skilled in the art by referring to the following exemplary aspects and best modes, as well as the accompanying drawings.

[0007] In order to facilitate an understanding of the outline of the present invention, the following examples are given of embodiments according to the present invention.

[0008] In an aspect according to the present invention, a vehicle weight estimation device that estimates the weight of a vehicle having wheels attached thereto includes a vehicle weight estimation unit that estimates the weight of the vehicle using a physical quantity that includes the acceleration of the vehicle as a component, a wheel diameter calculation unit that calculates the dynamic load radius of the wheel using a physical quantity that includes the speed of the vehicle as a component, and a vehicle weight update unit that acquires the acceleration and the speed of the vehicle at different times and updates the weight of the vehicle estimated using the dynamic load radius.

[0009] In an aspect according to the present invention, the vehicle weight update unit acquires the vehicle acceleration and the vehicle speed at different times and updates the vehicle weight estimated by the vehicle weight estimator using the vehicle dynamic load radius (synonymous with wheel diameter or tire-loaded radius) calculated by the wheel diameter calculation unit. According to the first aspect, for example, a physical quantity including acceleration as a component is acquired at a timing when the vehicle acceleration is relatively high immediately after the vehicle starts, and a physical quantity including vehicle speed as a component is acquired at a timing when the vehicle speed is relatively high some time after the start. The acquired vehicle acceleration and vehicle speed are reflected in the calculations of the weight estimator that estimates the vehicle weight and the wheel diameter calculation unit that calculates the vehicle dynamic load radius (wheel diameter). Finally, the vehicle weight update unit updates the vehicle weight estimated by the vehicle weight estimator using the dynamic load radius calculated by the wheel diameter calculation unit, thereby relatively reducing sensor noise. This reduces the error included in the vehicle weight estimation result estimated by the vehicle weight estimator, thereby improving the accuracy of the vehicle weight estimation. Although the dynamic load radius of the wheel also changes during this time, the effect of this change on the vehicle weight estimation is small enough (change in dynamic load radius << sensor noise) that it does not affect the practical accuracy (±50 kg), making it possible to estimate the vehicle weight with high accuracy.

[0010] In estimating the vehicle weight, the vehicle weight estimation unit can estimate the momentum generated in the vehicle by calculating the equation of motion F=ma. Here, F is the engine output minus various running resistance values, and the longitudinal G caused by the engine can be calculated by dividing the wheel torque τ by the value obtained by multiplying the vehicle weight by the wheel radius. Furthermore, m indicates the vehicle weight to be estimated, and a indicates the vehicle acceleration, for example, the value of the G sensor provided on the vehicle that detects the longitudinal G of the vehicle. The vehicle weight estimated by modifying the above-mentioned equation F=ma can be expressed, for example, by the calculation equation shown in step ST103 in Figure 4 (Equation 8, described later). Here, G ｓｅｎｓ１ , G ｓｅｎｓｅ２ is the vehicle's passing point T １ , T ２ The values ​​of the front and rear G sensors, τ1 and τ2, at the vehicle passing point T １ , T ２ where R is the dynamic load radius (wheel diameter), Cd is the air resistance coefficient of the vehicle, V １ , V ２ is the vehicle's passing point T １ , T ２ The wheel diameter calculation unit calculates the wheel dynamic load radius R by, for example, using the equation V=ωR (Equation 9, described later) which shows the relationship between the estimated vehicle speed V obtained by integrating the longitudinal G of the vehicle as shown in step ST107 of FIG. 4 and the angular velocity ω of the wheel, as R=V / ω. Note that the wheel diameter calculation unit can also calculate the wheel dynamic load radius R by calculating the sensor value of the longitudinal G of the vehicle and the amount of change (differential value) in the rotation speed of the drive shaft.

[0011] Fig. 1 is a diagram schematically showing the configuration of a vehicle in which a vehicle weight estimation device according to an embodiment of the present invention is implemented in an ECU. Fig. 2 is a block diagram showing an example of the functional configuration of a vehicle weight estimation device according to an embodiment of the present invention. Fig. 3(a) is a block diagram showing an example of the internal configuration of a vehicle weight update unit of Fig. 2, and Fig. 3(b) is a block diagram showing another example of the internal configuration of the vehicle weight update unit of Fig. 2. Fig. 4 is a flowchart showing an example of the operation of a vehicle weight estimation device according to an embodiment of the present invention. Fig. 5 is a block diagram showing the functional configuration of a modified example of a vehicle weight estimation device according to an embodiment of the present invention.

[0012] The best mode described below is used to facilitate understanding of the present invention, and therefore, those skilled in the art should be aware that the present invention is not unduly limited by the mode described below (hereinafter referred to as the present mode).

[0013] [Configuration of the Embodiment] (Vehicle Configuration) FIG. 1 is a diagram schematically illustrating the configuration of a vehicle in which a vehicle weight estimation device according to this embodiment is implemented in an ECU. As shown in FIG. 1, a vehicle 900 includes a suspension 100, a vehicle body 200, wheels 300, tires 310, a steering member 410, a steering shaft 420, a steering torque sensor 430 that detects steering torque applied to the steering shaft 420, a steering angle sensor 440, a torque application unit 460, a rack and pinion mechanism 470, a power steering device 400 including a rack shaft 480, a vehicle speed sensor 450 that detects vehicle speed (V), an engine 500, an ECU (Electronic Control Unit) 600, a power generator 700, and a battery 800. Two front wheels 300A and 300B of the vehicle 900 are steered wheels. The vehicle weight estimation device according to this embodiment (see 10A in FIG. 2) is implemented in the ECU 600. Details will be described later.

[0014] The letters A to E in the symbols each represent a position on the vehicle 900. A represents the position on the front left of the vehicle 900, B represents the position on the front right of the vehicle 900, C represents the rear left of the vehicle 900, D represents the rear right of the vehicle 900, and E represents the rear of the vehicle 900.

[0015] The vehicle 900 also includes a wheel speed sensor 320 provided for each wheel 300 and detecting the wheel speed (λ) of each wheel 300, a lateral G sensor 330 for detecting the lateral acceleration of the vehicle 900 (hereinafter also referred to as "lateral G"), and a front-rear G sensor 340 for detecting the longitudinal acceleration of the vehicle 900 (hereinafter also referred to as "front-rear G") (hereinafter, the output value of the front-rear G sensor 340 is referred to as "G"). ｓｅｎｓ "), a yaw rate sensor 350 that detects the yaw rate of the vehicle 900, a wheel torque sensor 510 that estimates the torque (wheel torque (τ)) that the engine 500 generates on a drive shaft (not shown), an engine speed sensor 520 that detects the speed of the engine 500, and a brake pressure sensor 530 that detects the pressure applied to the brake fluid of the brake device. As described above, the wheel torque is the torque applied to the wheels of the vehicle 900, and corresponds to the driving force of the vehicle 900.

[0016] Furthermore, vehicle 900 is equipped with a fuel sensor 360 that detects the amount of fuel (gasoline) in a fuel tank (not shown), a key position sensor 490 that detects the operating position of a key attached to the driver's seat of vehicle 900, a door opening / closing sensor 550 that detects the opening / closing of each door of vehicle 900, and a gear position sensor 540 that detects the connection position of the gear of vehicle 900. Note that door opening / closing sensor 550E detects the opening / closing of the trunk door (back door) of vehicle 900.

[0017] Output values ​​of various sensors are supplied to ECU 600, and control signals are transmitted from ECU 600 to each unit via CAN (Controller Area Network) 370. Each sensor may be newly provided for estimating vehicle weight, which will be described later, but from the standpoint of cost, it is preferable that the sensors are existing sensors in vehicle 900.

[0018] 2 is a block diagram showing an example of the functional configuration of the vehicle weight estimation device 10A (implemented in the ECU 600) according to this embodiment. The vehicle weight estimation device 10A according to this embodiment includes a vehicle weight estimation unit 11, a wheel diameter calculation unit 12, and a vehicle weight update unit 13 in order to estimate the weight of the vehicle 900 having the wheels 300 attached thereto.

[0019] The vehicle weight estimation unit 11 can estimate the weight of the vehicle 900 using a physical quantity that includes the acceleration of the vehicle 900 as a component. The vehicle weight estimation unit 11 may estimate the weight of the vehicle 900 using the difference (pure increase) in the acceleration of the vehicle 900 at any two or more points as the physical quantity that includes acceleration as a component. The vehicle weight estimation unit 11 may estimate the weight m of the vehicle 900 using an equation of motion that uses a physical quantity that includes the acceleration of the vehicle 900 as a component and a physical quantity that includes the vehicle speed of the vehicle 900 as a component.

[0020] In estimating the vehicle weight m, the vehicle weight estimation unit 11 can estimate the momentum generated in the vehicle 900 by calculating the equation of motion F=ma. Here, F is the engine output minus various running resistance values, and the longitudinal G caused by the engine can be obtained by dividing the wheel torque by the value obtained by multiplying the vehicle weight by the wheel radius. Furthermore, m indicates the vehicle weight to be estimated, and a indicates the vehicle acceleration, for example, the detection value of the longitudinal G sensor 340 provided on the vehicle that detects the longitudinal G of the vehicle. The weight of the vehicle 900 obtained by modifying the above equation of motion F=ma can be expressed by, for example, the calculation formula shown in step ST103 in FIG. 4, which will be described later. Here, G ｓｅｎｓ１ , G ｓｅｎｓｅ２ is the vehicle's passing point T １ , T ２ are the detection values ​​of the respective front and rear G sensors 340 at the passing point T １ , T ２ are the wheel torques at the respective positions, and R is the dynamic load radius (wheel diameter) of the wheel 300.

[0021] The wheel diameter calculation unit 12 can calculate the dynamic load radius R (wheel diameter) of the wheel 300 using a physical quantity that includes the speed of the vehicle 900 as a component. The wheel diameter calculation unit 12 may calculate the dynamic load radius R (wheel diameter) of the wheel 300 using the difference (pure increase) between the speeds of the vehicle 900 at any two or more points as a physical quantity that includes the speed of the vehicle 900 (estimated vehicle speed V) as a component. When calculating the dynamic load radius R (wheel diameter) of the wheel 300, the wheel diameter calculation unit 12 can, for example, calculate R = V / ω from the equation V = ωR that indicates the relationship between the estimated vehicle speed V of the vehicle 900 obtained by integrating the longitudinal G of the vehicle 900 shown in step ST107 in FIG. 4 and the wheel angular velocity ω of the wheel 300. Note that the dynamic load radius R can also be calculated by calculating the detection value of the longitudinal G sensor 340 of the vehicle 900 and the amount of change (differential value) in the rotation speed of the drive shaft.

[0022] The wheel diameter calculation unit 12 calculates the dynamic load radius R (wheel diameter) of the wheel 300 when a predetermined condition is satisfied, and may output the previously calculated dynamic load radius R (wheel diameter) of the wheel 300 as valid to the vehicle weight update unit 13 until the predetermined condition is satisfied. Here, the "predetermined condition" means, for example, that the acceleration of the vehicle 900 continues at a certain level or higher until a predetermined time has elapsed since the start of acceleration, and that the dynamic load radius R (wheel diameter) of the wheel 300 and the estimated vehicle speed V estimated from the acceleration are proportional to each other so that acceleration can be continued for the predetermined time without the generation of a deceleration force (deceleration due to braking).

[0023] The wheel diameter calculation unit 12 may calculate the dynamic load radius of the wheel 300 a predetermined number of times at a predetermined interval, and until the predetermined number of times is reached, use the dynamic load radius of the wheel 300 calculated before reaching that number, and determine a range of values ​​that are higher than the values ​​calculated the predetermined number of times to calculate the dynamic load radius of the wheel 300.

[0024] The vehicle weight updating unit 13 can acquire the acceleration of the vehicle 900 and the speed of the vehicle 900 at different times, and update the weight of the vehicle 900 estimated using the dynamic load radius. The vehicle weight updating unit 13 may calculate a correction term for correcting an error in the equation of motion using the dynamic load radius of the vehicle 900, and correct the error in the equation of motion by adding the correction term to the weight of the vehicle 900 estimated by the vehicle weight estimation unit 11. The weight updating unit 13 may calculate a correction gain for correcting an error in the equation of motion using the dynamic load radius of the vehicle 900, and correct the error in the equation of motion by multiplying the weight of the vehicle 900 estimated by the vehicle weight estimation unit 11 by the correction gain.

[0025] In the former case, the vehicle weight updating unit 13 is configured with a correction value calculation unit 131a and a weight determination unit 132a, for example, as shown in Fig. 3(a). The correction value calculation unit 131a calculates a correction term for correcting an error in the equation of motion using the dynamic load radius R of the vehicle 900, and outputs the correction term to the weight determination unit 132a. The weight determination unit 132a can correct an error in the equation of motion by adding the correction term to the weight of the vehicle 900 estimated by the vehicle weight estimation unit 11.

[0026] In the latter case, the vehicle weight updating unit 13 is composed of, for example, a correction value calculation unit 131b and a weight determination unit 132b, as shown in Fig. 3(b). The correction value calculation unit 131b calculates a correction gain for correcting an error in the equation of motion using the dynamic load radius R of the vehicle 900, and outputs the correction gain to the weight determination unit 132b. The weight determination unit 132b can correct an error in the equation of motion by multiplying the weight of the vehicle 900 estimated by the vehicle weight estimation unit 11 by the correction gain. In calculating the correction term, the correction term calculation unit (131a or 131b) acquires detection values ​​from various sensors, such as the wheel speed sensor 320 (see FIG. 1) or a tire air pressure sensor or air temperature sensor (not shown), and sets a predefined weighting coefficient (a value defined by verifying the reliability of the calculated dynamic load radius R of the wheel 300) for each detection value in order to improve the accuracy of estimating the vehicle weight, thereby allowing the wheel diameter calculation unit 12 to reflect the detected values ​​in its calculation of the dynamic load radius R (wheel diameter).

[0027] [Operation of the embodiment] Fig. 4 is a flowchart showing an example of the operation of the vehicle weight estimation device 10A according to this embodiment. Hereinafter, the operation of the vehicle weight estimation device 10A according to this embodiment shown in Figs. 2 and 3 will be described in detail with reference to the flowchart of Fig. 4.

[0028] 4, in the vehicle weight estimation device 10A according to this embodiment, first, the vehicle weight estimation unit 11 calculates the acceleration G ｓｅｎｓ is equal to or greater than a predetermined value (step ST101). Here, the "predetermined value" is, for example, the value of the acceleration of the vehicle 900 at the start. Here, the acceleration G ｓｅｎｓ is equal to or greater than the predetermined value ("YES" in step ST101), the vehicle weight estimation unit 11 calculates the acceleration value G ｓｅｎｓ (step ST102), and estimate the weight of the vehicle 900 using the equation of motion F=ma (step ST103). ｓｅｎｓ In addition to the above, the wheel diameter R and the wheel torque τ are also used.

[0029] As shown in FIG. 1, the vehicle 900 is provided with a front-rear G sensor 340 that detects the front-rear G of the vehicle 900. The output value of the front-rear G sensor 340 is G ｓｅｎｓ is the gravity acceleration component of the vehicle body pitch angle component of the acceleration (G) parallel to the road surface and the sum of the road surface angle and the vehicle body pitch angle, and can be expressed by the following (Equation 1). ｓｅｎｓ represents the output value of the front-rear G sensor 340, Gx represents the G parallel to the road surface, and G ｇｒａｖ represents the gravitational acceleration, θp represents the pitch angle of the vehicle body, and θr represents the road surface angle. Note that for θp and θr, a tilt that shifts the load toward the rear side of the vehicle 900 is represented by a positive sign, and a tilt that shifts the load toward the front side of the vehicle 900 is represented by a negative sign.

[0030]

[0031] Here, if the pitch angle θp of the vehicle body is assumed to be sufficiently small and approximated as θp≈0, then the above (Equation 1) can be expressed as the following (Equation 1′).

[0032]

[0033] Furthermore, Gx, which is G parallel to the road surface, is obtained by subtracting various running resistance values ​​from the longitudinal G derived from the engine output, and can be expressed by the following (Equation 2): In (Equation 2), Gp represents the longitudinal G derived from the engine output, Gair represents the air resistance component, and Gd represents the transmission resistance component.

[0034]

[0035] Here, Gp, which is the longitudinal G derived from the engine output, can be calculated by dividing the wheel torque by the value obtained by multiplying the vehicle weight by the wheel radius, and can be expressed by the following (Equation 3): In the following (Equation 3), τ represents the wheel torque, m represents the vehicle weight, and R represents the wheel diameter.

[0036]

[0037] Here, "wheel torque" refers to torque generated by the drive source of the vehicle 900 while it is running, acting on the wheels 300, and acting in a direction that accelerates or decelerates the vehicle 900. For example, in a vehicle 900 using an internal combustion engine as a drive source, the wheel torque is the torque applied to the wheels 300 of the vehicle 900. The wheel torque of an internal combustion engine is calculated by estimating the torque generated by the internal combustion engine from the air-fuel ratio, outside temperature, throttle valve opening amount, etc., and multiplying it by a transmission loss coefficient set for each vehicle and a predetermined reduction ratio for each reduction mechanism. Also, in a vehicle 900 having electric motors independently installed in the wheels 300 as drive sources, the wheel torque is the sum of the torques applied to each wheel 300 of the vehicle 900. The wheel torque of the vehicle 900 is calculated by multiplying the torque estimated from the work efficiency and applied voltage of each motor by a set transmission loss coefficient and a predetermined reduction ratio for each reduction mechanism. Furthermore, if the vehicle 900 further includes a differential control device (LSD) such as an electric differential, the driving force may be calculated by further referring to the operating conditions of these devices.

[0038] G, the air resistance component ａｉｒ can be calculated by multiplying the air resistance coefficient specific to the vehicle 900 by the square of the vehicle speed and dividing the result by the vehicle weight, and can be expressed by the following (Equation 4): In the following (Equation 4), Cd represents the air resistance coefficient of the vehicle, and V represents the vehicle speed.

[0039]

[0040] Here, at two passing points T1 and T2 with a predetermined interval between them, the value G of the front-rear G sensor 340 is ｓｅｎｓ The predetermined interval may be a time interval, a distance interval, or a combination thereof. ｓｅｎｓ１ is expressed by the following (Equation 1'-1), and Gx, which is G parallel to the road surface, is expressed by the following (Equation 2-1). Ｇｓｅｎｓ２ is expressed by the following (Equation 1'-2), and Gx, which is G parallel to the road surface, is expressed by the following (Equation 2-2). Note that the subscript "1" in the equation indicates various values ​​at passing point T1, and the subscript "2" in the equation indicates various values ​​at passing point T2.

[0041]

[0042] At this time, if the road surface conditions, road surface material, and other conditions differ between passing points T1 and T2, the transfer resistance component Gd will change, which may have an adverse effect on the accuracy of vehicle weight estimation. Therefore, it is desirable that the predetermined interval is sufficiently short so that the road surface conditions, road surface material, and other conditions are not expected to change. Here, (Equation 1'-1) and (Equation 1'-2) are transformed into the following equations, and (Equation 1''-1) and (Equation 1''-2), respectively.

[0043]

[0044] And, as a process for estimating vehicle weight, G ｘ１ -G ｘ２ Calculate the following. ｘ１ -G ｘ２ is expressed by the following (Equation 5).

[0045]

[0046] G in (Equation 5) ｇｒａｖ sinθ ｒ１ and G ｇｒａｖ sinθ ｒ２ By substituting the right-hand sides of equations (1''-1) and (1''-2) into and expanding them, the following equation (6) is obtained. G in (6) ｐ１ , G ｐ２ Substituting the right side of (Equation 3) into G of (Equation 6) ａｉｒ１ , G ａｉｒ２ By substituting the right side of (Equation 4) into (Equation 6'), (Equation 6') is obtained. By solving (Equation 6') for the vehicle weight m, (Equation 7) is obtained.

[0047]

[0048] Since the left side m of (Equation 7) is the vehicle weight as described above, the weight of the vehicle 900 can be estimated by calculating the right side of (Equation 7).

[0049] As described above, the transmission resistance component Gd varies depending on the road surface condition, material, etc. Therefore, it may be difficult to sequentially acquire the transmission resistance component Gd in the traveling vehicle 900 and use it as an estimation element. ｄ１ and G ｄ２ When the values ​​are equal, G in Eq. ｄ１ , G ｄ２ can be cancelled out, and (Equation 7) is transformed into the following (Equation 8): According to (Equation 8), the vehicle weight m can be estimated regardless of the transmission resistance component.

[0050]

[0051] Meanwhile, the wheel diameter calculation unit 12 determines whether the vehicle speed is equal to or greater than a predetermined value (step ST104). Here, the "predetermined value" refers to the value of the vehicle speed some time after the vehicle starts moving. Here, the integrated value of the longitudinal G of the vehicle 900 is used as the estimated vehicle speed V. If the estimated vehicle speed of the vehicle 900 is equal to or greater than the predetermined value ("YES" in step ST104), the wheel diameter calculation unit 12 acquires the estimated vehicle speed V (step ST105) and further determines whether predetermined conditions for calculating the wheel diameter are satisfied (step ST106). Here, the "predetermined conditions" refer to, for example, that the acceleration of the vehicle 900 is maintained at a constant level or higher for a predetermined time after the vehicle 900 starts accelerating, and that the vehicle speed estimated from the wheel diameter and the acceleration are proportional to each other so that acceleration can be continued for the predetermined time without generating a deceleration force.

[0052] If it is determined that the predetermined condition is satisfied ("YES" in step ST106), the wheel diameter calculation unit 12 calculates the wheel diameter R according to the following (Equation 10) based on the estimated vehicle speed V estimated based on the following (Equation 9) and the separately input wheel angular speed ω (step ST107). That is, the wheel diameter calculation unit 12 calculates the dynamic load radius R (wheel diameter) of the wheel 300 using a physical quantity including the estimated vehicle speed V of the vehicle 900 as a component. Note that the wheel diameter calculation unit 12 uses the difference (pure increase) between the speeds V of the vehicle 900 at any two or more points T1 and T2 as the difference and uses this difference for calculations in the vehicle weight estimation unit 11 and the wheel diameter calculation unit 12. This can further reduce sensor noise and ultimately improve the accuracy of vehicle weight estimation. The speed V may be obtained by first calculating the difference in acceleration a and then integrating it, or the order of the difference and integration may be reversed. Alternatively, known means can be used, such as using a GPS sensor instead of integrating the acceleration a, or obtaining the dynamic load radius R from the amount of fuel used and the rotation speed of the engine 500. Furthermore, the method of calculating the dynamic load radius R is not limited to the formula defined in (Formula 10), and if the vehicle 900 has a means for obtaining the internal pressure of the tire 310, the dynamic load radius R may be obtained by estimating it from the internal pressure, or if the vehicle 900 has another device, such as the power steering device 400, which has a function for calculating the dynamic load radius R, the dynamic load radius R may be obtained from the power steering device 400.

[0053]

[0054] The sprung mass of the vehicle 900 may change during a single use of the vehicle 900 (between ignition ON and OFF), and the engine may not be turned off due to passengers getting in and out of the vehicle, loading and unloading, etc. Therefore, in actual operation, it is preferable to estimate the vehicle weight each time the vehicle stops. On the other hand, the load radius R (wheel diameter) of the wheel 300 is unlikely to change during a single use of the vehicle 900, and tire 310 wear during a single use will only cause negligible differences. For this reason, the tire 310 is replaced when the vehicle 900 is not in use. Therefore, in actual operation, vehicle weight estimation only needs to be performed once immediately after the start of use, and the numerical values ​​can be reused even if vehicle weight estimation is required again. For this reason, the computational load on the ECU 600 can be reduced by stopping the calculation for estimation when the number of calculations reaches a predetermined number.

[0055] On the other hand, if it is determined in step ST106 that the predetermined condition is not satisfied ("NO" in step ST106), the wheel diameter calculation unit 12 acquires the previously calculated dynamic load radius R (wheel diameter) until the predetermined condition is satisfied (step ST108). That is, the wheel diameter calculation unit 12 calculates the dynamic load radius (wheel diameter) a predetermined number of times at predetermined intervals, uses the previously calculated wheel diameter R until the predetermined number of times is reached, determines a range of cover values ​​from the values ​​calculated the predetermined number of times, calculates the dynamic load radius R (wheel diameter), and outputs the calculated value to the vehicle weight update unit 13. This makes it possible to avoid updating the vehicle weight when there is an error in the estimation result.

[0056] Finally, the vehicle weight updating unit 13 acquires the acceleration a of the vehicle 900 and the vehicle speed V of the vehicle 900 at different times, and updates the weight m of the vehicle 900 estimated using the dynamic load radius R (wheel diameter) calculated by the wheel diameter calculation unit 12 (step ST109). When updating the weight of the vehicle 900, for example, the correction value calculation unit 131a shown in Figure 3(a) in the vehicle weight updating unit 13 calculates a correction term that corrects an error in the equation of motion using the dynamic load radius R (wheel diameter) of the vehicle 900, and the weight determination unit 132a adds the correction term calculated by the correction value calculation unit 131a to the weight of the vehicle 900 estimated by the vehicle weight estimation unit 11 to correct the error in the equation of motion.

[0057] Here, the estimated vehicle weight before correction output by the vehicle weight estimation unit 11 is supplied to one input terminal of the weight determination unit 132a as a provisional vehicle weight estimated using a catalog value for the dynamic load radius, and a correction term calculated by the correction value calculation unit 131a is supplied to the other input terminal. In calculating the correction term, in order to improve the accuracy of the vehicle weight estimation, the correction value calculation unit 131a acquires detected values ​​from various sensors, such as the wheel speed sensor 320 (see FIG. 1) or a tire air pressure sensor or air temperature sensor (not shown), and sets a predefined weighting coefficient (a value defined by verifying the reliability of the calculated dynamic load radius of the wheel 300) for each detected value, thereby allowing the wheel diameter calculation unit 12 to reflect the detected values ​​in the calculation of the dynamic load radius. The weight determination unit 132a finally corrects the error in the equation of motion by adding the correction term calculated by the correction value calculation unit 131a to the weight of the vehicle 900 estimated by the vehicle weight estimation unit 11, thereby correcting the error in the vehicle weight estimation calculation result taking into account the deformation.

[0058] In addition, the vehicle weight update unit 13 may, for example, have a correction value calculation unit 131b shown in Figure 3(b) calculate a correction gain that corrects the error in the equation of motion using the dynamic load radius of the wheel 300, and a weight determination unit 132b multiply the weight of the vehicle 900 estimated by the vehicle weight estimation unit 11 (estimated vehicle weight based on the wheel diameter using the catalog value) by the correction gain to correct the error in the equation of motion.

[0059] In this way, by incorporating the dynamic load radius R (wheel diameter) of the wheel 300 into the equation of motion, vehicle weight is estimated with the wheel diameter set to a fixed value (catalog value), and error correction that takes deformation into account through correction (correcting the error in the equation of motion by adding a correction term) is calculated separately, thereby enabling highly accurate estimation of vehicle weight. Note that when reliability is high, the weighting coefficient can be set to be high accordingly and reflected in the estimation of the vehicle weight of the vehicle 900, thereby further improving the accuracy of the weight estimation of the vehicle 900 by the vehicle weight estimation device 10A.

[0060] 1, the vehicle weight estimation device of this embodiment is a vehicle weight estimation device 10A (implemented in the ECU 600) that estimates the weight of a vehicle 900 having attached wheels 300. The vehicle weight estimation device 10A includes a vehicle weight estimation unit 11 that estimates the weight of the vehicle 900 using a physical quantity that includes the acceleration of the vehicle 900 as a component, a wheel diameter calculation unit 12 that calculates the dynamic load radius of the wheel 300 using a physical quantity that includes the speed of the vehicle 900 as a component, and a vehicle weight update unit 13 that acquires the acceleration and the speed of the vehicle 900 at different times and updates the weight m of the vehicle 900 estimated using the dynamic load radius R, as shown in FIG.

[0061] In the vehicle weight estimation device 10A of this embodiment, the vehicle weight update unit 13 acquires the acceleration of the vehicle 900 and the speed of the vehicle 900 at different times, and can update the weight m of the vehicle 900 estimated by the vehicle weight estimation unit 11 using the dynamic load radius R (synonymous with the wheel diameter or tire load radius) of the vehicle 900 calculated by the wheel diameter calculation unit 12. According to the vehicle weight estimation device 10A of this embodiment, for example, a physical quantity containing acceleration as a component is obtained at a timing when the acceleration a is relatively large immediately after the vehicle 900 starts, and a physical quantity containing the speed of the vehicle 900 as a component is obtained at a timing when the vehicle speed V is relatively large some time after the start, and the obtained acceleration and speed V of the vehicle 900 are reflected in the calculations of a weight estimation unit that estimates the weight m of the vehicle 900 and a wheel diameter calculation unit 12 that calculates the dynamic load radius R of the vehicle 900, and finally, the vehicle weight update unit 13 updates the weight of the vehicle 900 estimated by the vehicle weight estimation unit 11 using the dynamic load radius R calculated by the wheel diameter calculation unit 12, thereby relatively reducing sensor noise, and as a result, the error included in the vehicle weight estimation result estimated by the vehicle weight estimation unit 11 is reduced and the accuracy of the vehicle weight estimation can be improved. Although the dynamic load radius R of the wheel 300 also changes during this time, the effect of this change on the weight estimation of the vehicle 900 is small enough (change in dynamic load radius << sensor noise) that it does not affect the practical accuracy (±50 kg), making it possible to estimate the vehicle weight with high accuracy.

[0062] In estimating the weight m of the vehicle 900, the vehicle weight estimation unit 11 can estimate the momentum generated in the vehicle 900 by calculating the equation of motion F=ma. Here, F is the engine output minus various running resistance values, and the longitudinal G caused by the engine can be obtained by dividing the wheel torque τ by the value obtained by multiplying the vehicle weight by the wheel radius. Also, m is the weight of the vehicle 900 to be estimated, and a is the acceleration of the vehicle, for example, the value of the longitudinal G sensor 340 (see FIG. 1) provided on the vehicle 900 that detects the longitudinal G of the vehicle 900. The weight of the vehicle 900 estimated by modifying the above-mentioned equation F=ma can be expressed, for example, by the calculation equation (Equation 8) shown in step ST103 in FIG. 4. Here, G ｓｅｎｓ１ , G ｓｅｎｓｅ２ is the passing point T of the vehicle 900 １ , T ２ The measured values ​​τ1 and τ2 of the respective front and rear G sensors 340 at the passing point T １ , T ２ where R is the wheel radius, Cd is the air resistance coefficient of the vehicle 900, and V １ , V ２ is the passing point T of the vehicle 900 １ , T ２ The dynamic load radius R of the wheel 4300 is calculated by the wheel diameter calculation unit 12, for example, using the equation V=ωR (Equation 9) which shows the relationship between the estimated speed V of the vehicle 900 obtained by integrating the longitudinal G of the vehicle 900 in step ST107 of FIG. 4 and the angular velocity ω of the wheel, as R=V / ω. Note that the dynamic load radius R can also be calculated by calculating the sensor value of the longitudinal G of the vehicle 900 and the amount of change (differential value) in the drive shaft rotation speed.

[0063] Furthermore, in the vehicle weight estimation device 10A of this embodiment, the vehicle weight estimation unit 11 estimates the weight of the vehicle 900 using the difference in the acceleration a of the vehicle 900 at any two or more points T1 and T2 as a physical quantity containing the acceleration a as a component, and the wheel diameter calculation unit 12 calculates the dynamic load radius R of the wheel 300 using the difference in the speed (vehicle speed V) of the vehicle 900 at any two or more points T1 and T2 as a physical quantity containing the speed a of the vehicle 900 as a component. In this way, the physical quantity containing the acceleration a of the vehicle 900 as a component is used as the difference (pure increase) in the acceleration a of the vehicle 900 at any two or more points, and the physical quantity containing the speed of the vehicle 900 as a component is used as the difference (pure increase) in the speed of the vehicle 900 at any two or more points, and these are used in the calculations of the vehicle weight estimation unit 1 and the wheel diameter calculation unit 12, respectively. This makes it possible to further reduce sensor noise, and as a result, to improve the accuracy of vehicle weight estimation.

[0064] Furthermore, in the vehicle weight estimation device 10A of this embodiment, the wheel diameter calculation unit 12 calculates the dynamic load radius R of the wheel 300 when a predetermined condition is satisfied, and outputs the previously calculated dynamic load radius R of the wheel 300 to the vehicle weight update unit 13 as valid until the predetermined condition is satisfied. Here, the "predetermined condition" refers to, for example, that the acceleration is maintained at a certain level or higher for a predetermined time from the start of vehicle acceleration, and that the wheel diameter and the estimated vehicle speed estimated from the acceleration are proportional to each other so that acceleration is continued for the predetermined time without the generation of a deceleration force (deceleration due to braking). In this way, the accuracy of the estimation can be improved by avoiding updating the estimated result of the vehicle weight m using the dynamic load radius R of the wheel 300 when the number of calculations does not reach the predetermined number. Furthermore, the calculation load can be reduced by stopping the estimation of the vehicle weight using the dynamic load radius of the wheel when the number of calculations reaches the predetermined number.

[0065] Furthermore, in the vehicle weight estimation device 10A of this embodiment, the wheel diameter calculation unit 12 calculates the dynamic load radius R of the wheel 300 a predetermined number of times at predetermined intervals, and until the predetermined number of calculations is reached, the wheel diameter calculation unit 12 uses the dynamic load radius of the wheel 300 calculated before reaching the predetermined number of calculations, and determines a range of values ​​that are higher than the predetermined number of calculations to calculate the dynamic load radius R of the wheel. This makes it possible to avoid updating the vehicle weight m when there is an error in the estimation result.

[0066] Furthermore, in the vehicle weight estimation device 10A of this embodiment, the vehicle weight estimation unit 11 can estimate the weight of the vehicle 900 using an equation of motion F=ma that uses a physical quantity that includes as a component the acceleration a of the vehicle 900 and a physical quantity that includes as a component the speed (vehicle speed V) of the vehicle 900. The vehicle weight estimation unit 11 can easily estimate the weight of the vehicle 900 with high accuracy by, for example, acquiring the longitudinal G and driving force (wheel torque τ) of the vehicle 900 using sensors and simply performing data processing using, for example, the least squares method or the like.

[0067] Furthermore, in the vehicle weight estimation device 10A of this embodiment, the vehicle weight update unit 13 calculates a correction term for correcting an error in the equation of motion using the dynamic load radius R of the vehicle 900, and can correct the error in the equation of motion by adding the correction term calculated by a separate calculation to the weight of the vehicle 900. To improve the accuracy of vehicle weight estimation, detection values ​​are acquired from various sensors, such as the wheel speed sensor 320 (see FIG. 1 ) or a tire pressure sensor or air temperature sensor (not shown), and a predefined weighting coefficient (a value defined by verifying the reliability of the calculated dynamic load radius of the wheel 300) is set for each detection value, so that the wheel diameter calculation unit 12 can reflect the detection values ​​in the calculation of the dynamic load radius. In this way, by incorporating the dynamic load radius of the wheel 300 into the equation of motion, the wheel diameter is calculated as a fixed value (catalog value), and error correction (adding a correction term to correct the error in the equation of motion) that takes deformation into account through correction is calculated by a separate calculation, thereby enabling highly accurate vehicle weight estimation. Furthermore, if the reliability is high, the weighting coefficient can be set accordingly higher and reflected in the estimation of the vehicle weight of the vehicle 900, thereby further improving the accuracy of the weight estimation of the vehicle 900 by the vehicle weight estimation device 10A.

[0068] Furthermore, in the vehicle weight estimation device 10A of this embodiment, the vehicle weight update unit 13 can calculate a correction gain that corrects an error in the equation of motion using the dynamic load radius R of the vehicle 900, and can correct the error in the equation of motion by multiplying the vehicle weight m estimated by the vehicle weight estimation unit 11 by the correction gain calculated by a separate calculation. In this way, by incorporating the dynamic load radius of the wheel into the equation of motion, the wheel diameter is calculated as a fixed value (catalog value), and error correction that takes into account deformation due to correction (multiplying by the correction gain to correct the error in the equation of motion) is calculated by a separate calculation, thereby enabling highly accurate estimation of vehicle weight.

[0069] The vehicle weight estimation method of this embodiment is a vehicle weight estimation method for estimating the weight of a vehicle 900 having wheels 300 attached thereto, as shown in Fig. 1. The method includes, as shown in Fig. 4, an acceleration acquisition step for acquiring an acceleration a of the vehicle 900 (see ST102), a vehicle weight estimation step for estimating a weight m of the vehicle 900 using a physical quantity including the acquired acceleration a as a component (see ST103), a vehicle speed acquisition step for acquiring a speed (vehicle speed V) of the vehicle 900 at a timing different from that of the acceleration acquisition step (see ST104, ST105), a wheel diameter calculation step for calculating a dynamic load radius R of the wheel 300 using a physical quantity including the vehicle speed (vehicle speed V) acquired in the vehicle speed acquisition step as a component (see ST106 to ST108), and a vehicle weight update step for updating the weight m of the vehicle 900 using the dynamic load radius R of the vehicle 900 acquired in the wheel diameter acquisition step (see ST109).

[0070] According to the vehicle weight estimation method of this embodiment, in the acceleration acquisition step, for example, a physical quantity containing acceleration a as a component is acquired at a timing when acceleration a is relatively large immediately after the vehicle 900 starts moving, and in the vehicle speed acquisition step, for example, a physical quantity containing vehicle speed (vehicle speed V) as a component is acquired at a timing when vehicle speed V is relatively large some time after the start of the vehicle, and the acquired acceleration a and speed (vehicle speed V) of the vehicle 900 are reflected in the respective calculations in the vehicle weight estimation step and the wheel diameter calculation step. Finally, in the vehicle weight update step, the weight m of the vehicle 900 estimated in the vehicle weight estimation step is updated using the dynamic load radius R calculated in the wheel diameter calculation step, thereby making it possible to relatively reduce sensor noise, and as a result, the error included in the vehicle weight estimation result estimated in the vehicle weight estimation step is reduced, thereby improving the accuracy of the vehicle weight estimation. Although the dynamic load radius R of the wheel 300 also changes during this time, the effect of this change on the weight estimation of the vehicle 900 is small enough (change in dynamic load radius << sensor noise) that it does not affect the practical accuracy (±50 kg), making it possible to estimate the vehicle weight with high accuracy.

[0071] [Modification] Incidentally, if a stroke sensor is provided to obtain the load (sprung weight) of all wheels of a vehicle 900 while the vehicle is moving, there is no need to estimate the weight m of the vehicle 900 (because the unsprung weight hardly changes). However, this is not practical due to the high cost. Furthermore, even if a stroke sensor is not provided, even if an air pressure sensor is provided, it is not possible to determine whether the deformation is due to air replenishment or load. Therefore, even if the internal pressure is known, it is necessary to determine the vehicle weight, and a separate weight estimation using the equation of motion is required. Therefore, in the modification described below, for example, as shown in FIG. 5, a vehicle weight estimation device 10B that estimates the weight of a vehicle 900 having wheels 300 attached thereto is configured with at least a provisional vehicle weight estimation unit 21, a wheel diameter calculation unit 22, a correction amount calculation unit 23, and a vehicle weight determination unit 24.

[0072] In FIG. 5 , the provisional vehicle weight estimator 21 estimates a provisional vehicle weight m′ using a physical quantity with the dynamic load radius R of the wheel 300 as a predetermined value, and outputs the estimated provisional vehicle weight m′ to the weight determiner 24. The “predetermined value” refers to a fixed wheel radius R′ that is not calculated each time to solve the equation of motion. The wheel diameter calculator 22 receives the wheel speed λ calculated by the wheel speed calculator 25 and the estimated vehicle speed V calculated by the vehicle speed calculator 26 as inputs, calculates or determines the dynamic load radius R of the wheel 300, and outputs the calculated value to the correction value calculator 23. The correction amount calculator 23 uses the dynamic load radius R calculated by the wheel diameter calculator 22 to output, for example, a correction amount mc to the weight determiner 14, which corrects the error in the vehicle weight m, which is the difference between the provisional vehicle weight m′ and the provisional vehicle weight m′. The vehicle weight determiner 24 calculates the final estimated weight m from the provisional vehicle weight m′ and the correction amount mc.

[0073] In FIG. 5, the relationships are as follows: wheel torque τ / provisional dynamic load radius R' = provisional vehicle volume m' x acceleration a, vehicle speed V = dynamic load radius R x wheel speed λ, wheel torque τ / provisional dynamic load radius R' = provisional estimated vehicle weight m' x acceleration a, wheel torque τ / dynamic load radius R = provisional vehicle weight m' x acceleration a, and correction value mc = estimated vehicle weight m - provisional estimated vehicle weight m'.

[0074] As described above, a vehicle weight estimation device as a modified example is, for example, a vehicle weight estimation device 10B that estimates the weight of a vehicle 900 having wheels 300 attached thereto, as shown in Fig. 1. The vehicle weight estimation device 10B includes, for example, a provisional vehicle weight estimation unit 21 that estimates a provisional vehicle weight m' using a physical quantity in which the diameter of the wheel 300 is a predetermined value, a wheel diameter calculation unit 22 that calculates or determines a dynamic load radius R of the wheel 300, a correction amount calculation unit 23 that corrects an error in the vehicle weight using the dynamic load radius R calculated by the wheel diameter calculation unit 22, and a weight determination unit 14 that calculates a final corrected estimated weight m from the provisional vehicle weight m' and the correction amount mc, as shown in Fig. 5. The "predetermined value" here refers to a fixed wheel diameter R' that is not a value calculated each time to solve the equation of motion. The correction amount calculation unit 23 uses the dynamic load radius R calculated by the wheel diameter calculation unit 22 to calculate a correction amount mc for correcting an error in vehicle weight, which is the difference from the provisional vehicle weight m', and outputs the correction amount mc to the weight determination unit 14. The vehicle weight determination unit 24 calculates the final estimated weight m from the provisional vehicle weight m' and the correction amount mc.

[0075] According to the vehicle weight estimation device 10A of this embodiment shown in Figure 1, the dynamic load radius R (wheel diameter) of the wheel 300 is incorporated into the equation of motion that estimates the vehicle weight m, so if a failure occurs in the part that calculates the dynamic load radius R, it becomes impossible to estimate the vehicle weight. In contrast, according to the vehicle weight estimation device 10B as a modified example shown in Figure 5, the dynamic load radius R is calculated separately, so even if a failure occurs in one part, it is possible to maintain vehicle weight estimation using a fixed value, although with a decrease in accuracy.

[0076] [Additional Notes] As explained above, the present invention can be summarized as including at least the following items (1) to (9).

[0077] (1) A vehicle weight estimation device for estimating the weight of a vehicle having wheels attached thereto, the device comprising: a vehicle weight estimation unit for estimating the weight of the vehicle using a physical quantity including the acceleration of the vehicle as a component; a wheel diameter calculation unit for calculating a dynamic load radius of the wheel using a physical quantity including the speed of the vehicle as a component; and a vehicle weight update unit for acquiring the acceleration of the vehicle and the speed of the vehicle at different times and updating the estimated weight of the vehicle using the dynamic load radius. (2) In the vehicle weight estimation device, the vehicle weight estimation unit estimates the weight of the vehicle using a difference in acceleration of the vehicle at any two or more points as a physical quantity including the acceleration as a component, and the wheel diameter calculation unit calculates the dynamic load radius of the wheel using the difference in speed of the vehicle at any two or more points as a physical quantity including the speed of the vehicle as a component. (3) In the vehicle weight estimation device, the wheel diameter calculation unit calculates the dynamic load radius of the wheel when a predetermined condition is satisfied, and outputs the previously calculated dynamic load radius of the wheel to the vehicle weight update unit as valid until the predetermined condition is satisfied. (4) In the vehicle weight estimation device, the wheel diameter calculation unit calculates the dynamic load radius of the wheel a predetermined number of times at predetermined intervals, and until the predetermined number of times is reached, uses the dynamic load radius of the wheel calculated before reaching the predetermined number of times, and calculates the dynamic load radius of the wheel by determining a range of values ​​that are higher than the predetermined number of calculations. (5) In the vehicle weight estimation device, the vehicle weight estimation unit estimates the weight of the vehicle using an equation of motion that uses a physical quantity that includes the acceleration of the vehicle as a component and a physical quantity that includes the speed of the vehicle as a component. (6) In the vehicle weight estimation device, the vehicle weight update unit acquires the acceleration and speed of the vehicle at different times and updates the vehicle weight estimated using the dynamic load radius of the vehicle, calculates a correction term that corrects an error in the equation of motion using the dynamic load radius of the vehicle, and adds the correction term to the vehicle weight estimated by the vehicle weight estimation unit to correct the error in the equation of motion.(7) In the vehicle weight estimation device, a weight update unit acquires the acceleration and speed of the vehicle at different times and updates the vehicle weight estimated using the dynamic load radius of the vehicle. The weight update unit calculates a correction gain that corrects an error in the equation of motion using the dynamic load radius of the vehicle, and multiplies the weight of the vehicle estimated by the vehicle weight estimation unit by the correction gain to correct the error in the equation of motion.

[0078] (8) A vehicle weight estimation method for estimating the weight of a vehicle having wheels attached thereto, comprising: an acceleration acquisition step for acquiring an acceleration of the vehicle; a vehicle weight estimation step for estimating the weight of the vehicle using a physical quantity that includes the acquired acceleration as a component; a vehicle speed acquisition step for acquiring the speed of the vehicle at a timing different from that of the acceleration acquisition step; a wheel diameter calculation step for calculating a dynamic load radius of the wheel using the physical quantity that includes the vehicle speed acquired in the vehicle speed acquisition step as a component; and a vehicle weight update step for updating the weight of the vehicle using the dynamic load radius of the vehicle acquired in the wheel diameter acquisition step.

[0079] (9) A vehicle weight estimation device that estimates the weight of a vehicle having wheels attached thereto, comprising: a provisional vehicle weight estimation unit that estimates provisional vehicle weight using a physical quantity in which the diameter of the wheel is a predetermined value; a wheel diameter calculation unit that calculates or determines the dynamic load radius of the wheel; a correction amount calculation unit that corrects an error in vehicle weight using the dynamic load radius calculated by the wheel diameter calculation unit; and a weight determination unit that calculates a final corrected estimated weight from the provisional vehicle weight and the correction amount.

[0080] The present invention is not limited to the above-described exemplary embodiments, and those skilled in the art will be able to easily modify the above-described exemplary embodiments to the extent that they fall within the scope of the claims.

[0081] 10A, 10B... Vehicle weight estimation device, 11... Vehicle weight estimation unit, 12... Wheel diameter calculation unit, 13... Vehicle weight update unit, 21... Provisional weight estimation unit, 22... Wheel diameter calculation unit, 23... Correction amount calculation unit, 24... Weight determination unit, 25... Wheel speed calculation unit, 26... Vehicle speed calculation unit, 131a, 131b... Correction value calculation unit, 132a, 132b... Weight determination unit, 300... Wheel, 310... Tire, 320... Wheel speed sensor, 340... Front / rear G sensor, 510... Wheel torque sensor, 600... ECU, 900... Vehicle

Claims

1. A vehicle weight estimation device that estimates the weight of a vehicle having wheels attached thereto, comprising: a vehicle weight estimation unit that estimates the weight of the vehicle using a physical quantity that includes the acceleration of the vehicle as a component; a wheel diameter calculation unit that calculates the dynamic load radius of the wheel using a physical quantity that includes the speed of the vehicle as a component; and a vehicle weight update unit that acquires the acceleration and speed of the vehicle at different times and updates the weight of the vehicle estimated using the dynamic load radius.

2. A vehicle weight estimation device as described in claim 1, wherein the vehicle weight estimation unit estimates the weight of the vehicle using the difference in acceleration of the vehicle at any two or more points as a physical quantity containing the acceleration as a component, and the wheel diameter calculation unit calculates the dynamic load radius of the wheel using the difference in speed of the vehicle at any two or more points as a physical quantity containing the speed of the vehicle as a component.

3. A vehicle weight estimation device as described in claim 1, wherein the wheel diameter calculation unit calculates the dynamic load radius of the wheel when a predetermined condition is satisfied, and outputs the previously calculated dynamic load radius of the wheel to the vehicle weight update unit as valid until the predetermined condition is satisfied.

4. A vehicle weight estimation device as claimed in claim 1, wherein the wheel diameter calculation unit calculates the dynamic load radius of the wheel a predetermined number of times at predetermined intervals, and until the predetermined number of times is reached, uses the dynamic load radius of the wheel calculated before that time, and determines a range of values that are higher than the values calculated the predetermined number of times to calculate the dynamic load radius of the wheel.

5. A vehicle weight estimation device according to claim 1, wherein the vehicle weight estimation unit estimates the weight of the vehicle using an equation of motion that uses a physical quantity that includes the acceleration of the vehicle as a component and a physical quantity that includes the speed of the vehicle as a component.

6. A vehicle weight estimation device according to claim 5, wherein a vehicle weight update unit acquires the acceleration and speed of the vehicle at different times and updates the vehicle weight estimated using the dynamic load radius of the vehicle, calculates a correction term for correcting an error in the equation of motion using the dynamic load radius of the vehicle, and adds the correction term to the vehicle weight estimated by the vehicle weight estimation unit to correct the error in the equation of motion.

7. A vehicle weight estimation device according to claim 5, wherein a weight update unit that acquires the acceleration and speed of the vehicle at different times and updates the vehicle weight estimated using the dynamic load radius of the vehicle calculates a correction gain that corrects an error in the equation of motion using the dynamic load radius of the vehicle, and multiplies the vehicle weight estimated by the vehicle weight estimation unit by the correction gain to correct the error in the equation of motion.

8. A vehicle weight estimation method for estimating the weight of a vehicle having wheels attached thereto, comprising: an acceleration acquisition step for acquiring the acceleration of the vehicle; a vehicle weight estimation step for estimating the weight of the vehicle using a physical quantity that includes the acquired acceleration as a component; a vehicle speed acquisition step for acquiring the speed of the vehicle at a timing different from that of the acceleration acquisition step; a wheel diameter calculation step for calculating a dynamic load radius of the wheel using the physical quantity that includes the vehicle speed acquired in the vehicle speed acquisition step as a component; and a vehicle weight update step for updating the weight of the vehicle using the dynamic load radius of the vehicle acquired in the wheel diameter acquisition step.

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