JP6769272B2 - Vehicle weight estimation device and vehicle weight estimation method - Google Patents

Description

The present invention relates to a vehicle weight estimation device and a vehicle weight estimation method, and more specifically, to a vehicle weight estimation device and a vehicle weight estimation method for estimating the weight of a vehicle with high accuracy.

A device for estimating the weight of a vehicle based on a parameter that changes during the running of the vehicle has been proposed (see, for example, Patent Document 1). This device performs highly accurate estimation by not estimating the weight of the vehicle when the accelerator opening degree, which indicates the amount of depression of the accelerator pedal, fluctuates greatly.

Japanese Unexamined Patent Publication No. 2011-137534

By the way, when the rotational power transmitted to the propeller shaft suddenly increases, the propeller shaft is twisted, a force for returning the twist is generated, and the propeller shaft vibrates. In particular, the longer the propeller shaft, the greater the amount of twisting of the propeller shaft, and the greater the vibration. Therefore, the vibration becomes remarkable in a large vehicle such as a bus or a truck in which the axial length of the propeller shaft is longer than that of an ordinary passenger car.

When such vibration occurs, in the above-mentioned device, the rotation speed output from the transmission fluctuates. Therefore, the estimation error of the weight of the vehicle is large.

The present invention has been made in view of the above, and an object of the present invention is a vehicle weight estimation device and a vehicle weight estimation method for estimating the weight of a vehicle with high accuracy by reducing the estimation error due to the vibration of the propeller shaft. Is to provide.

The vehicle weight estimation device of the present invention that achieves the above object includes a power source, a transmission that shifts and outputs the rotational power input from the power source, and a propeller shaft that transmits the shifted rotational power. In a vehicle weight estimation device that estimates the weight of a vehicle having a differential gear that distributes the transmitted rotational power to each drive wheel, a parameter acquisition means that acquires parameters that change during the running of the vehicle. , While the parameters acquired by this parameter acquisition means are input and the estimation means that outputs the estimated value of the weight of the vehicle estimated based on the parameters and the propeller shaft are vibrated due to twisting. It is characterized by including a maintenance means for maintaining a pre-occurrence estimated value estimated by the estimation means before the vibration occurs as the weight of the vehicle.

In the vehicle weight estimation method of the present invention that achieves the above object, the rotational power input from the power source is changed by the transmission, and the rotational power transmitted via the propeller shaft is distributed to each drive wheel by the differential gear. In the vehicle weight estimation method for estimating the weight of the vehicle, parameters that change during the running of the vehicle are acquired, and based on the parameters, it is determined whether or not the propeller shaft is vibrated due to twisting, and the vibration is determined. This method is characterized in that the pre-occurrence estimated value estimated based on the parameters acquired before the vibration occurs as the weight of the vehicle is maintained while the above-mentioned is occurring.

According to the present invention, while the propeller shaft is vibrated due to twisting, the pre-occurrence estimated value estimated before the vibration is generated as the weight of the vehicle is maintained, so that the error due to the vibration is reduced until the error is reduced. A constant value can be maintained as the weight of the vehicle. This is advantageous in reducing the estimation error when vibration due to twisting occurs in the propeller shaft, and the weight of the vehicle can be estimated with high accuracy.

It is explanatory drawing which illustrates the embodiment of the vehicle weight estimation device of this invention. It is a block diagram which illustrates the control device of FIG. It is a block diagram which illustrates the vehicle weight calculation part of FIG. 2, and shows the state which a timer is off. It is a block diagram which illustrates the vehicle weight calculation part of FIG. 2, and shows the state which a timer is on. It is a flow figure which illustrates embodiment of the vehicle weight estimation method of this invention. It is a relational figure which illustrates the relationship between an engine rotation speed and an accelerator opening degree, and an engine torque. It is a relational figure which illustrates the relationship between the elapsed time and the rotation fluctuation of a propeller shaft.

Hereinafter, embodiments of the vehicle weight estimation device and the vehicle weight estimation method of the present invention will be described.

The vehicle weight estimation device 30 of the embodiment illustrated in FIGS. 1 to 4 is a device mounted on the vehicle 10 and estimates the weight of the vehicle 10 based on parameters that change during the traveling of the vehicle 10. Hereinafter, those with x and y attached to the code are variables, which indicate the detected values and estimated values of the sensor, etc., and those with k attached to the code indicate the time series, and this k is "1" for each sampling cycle ts. It increases by.

As illustrated in FIG. 1, in the vehicle 10 on which the vehicle weight estimation device 30 is mounted, the driver's cab (cab) 12 is arranged on the front side of the chassis 11, and the body 13 is arranged on the rear side of the chassis 11. ..

An engine 14, a clutch 15, a transmission 16, a propeller shaft 17, and a differential gear 18 are installed in the chassis 11. The rotational power of the engine 14 is transmitted to the transmission 16 via the clutch 15. The rotational power shifted by the transmission 16 is transmitted to the differential gear 18 through the propeller shaft 17 and distributed as driving force to the pair of driving wheels 19 which are the rear wheels. A torque converter may be interposed between the engine 14 and the clutch 15.

The control device 20 is electrically connected to the engine 14, the clutch 15, the transmission 16, and various sensors via signal lines indicated by alternate long and short dash lines. As various sensors, the driver's cab 12 is provided with an accelerator opening sensor 22 that detects the accelerator opening Ax from the amount of depression of the accelerator pedal 21, and a position sensor 24 that detects the lever position Px of the shift lever 23. A rotation speed sensor 25, a vehicle speed sensor 26, and an acceleration sensor 27 for detecting the rotation speed Nx of the crankshaft (not shown) of the engine 14 are installed in the chassis 11.

The control device 20 is hardware composed of a CPU that performs various information processing, an internal storage device that can read and write programs and information processing results used for performing the various information processing, and various interfaces.

As illustrated in FIG. 2, the control device 20 includes a control unit 28 that controls the engine 14, the clutch 15, and the transmission 16 and a vehicle weight calculation unit 31 that calculates the weight of the vehicle 10 as functional elements. are doing. In this embodiment, each functional element is stored as a program in the internal storage device, but each functional element may be configured by individual hardware.

The vehicle weight estimation device 30 of the present invention is composed of a position sensor 24, a rotation speed sensor 25, a vehicle speed sensor 26, an acceleration sensor 27, a control unit 28, and a vehicle weight calculation unit 31. Then, the vehicle weight calculation unit 31 functions as a parameter acquisition means, an estimation means, and a maintenance means, and the detection values of those sensors and the calculation results of the calculation unit are input and calculated based on each detection value and the calculation result. The result is output as an output value mx.

The control unit 28 is a functional element that functions as a part of the parameter acquisition means, and in this embodiment, the fuel injection amount Qx in the engine 14 is acquired for each sampling cycle ts. Since the fuel injection amount Qx is proportional to the injection time (drive pulse) of the injector (not shown) of the engine 14, it can be obtained from the total injection time.

The control unit 28 inputs the accelerator opening degree Ax detected by the accelerator opening degree sensor 22, and calculates the reference injection time based on the accelerator opening degree Ax. When the fuel injection amount based on this reference injection time is injected from the injector, the target torque TE is output as the torque output from the engine 14. Next, the control unit 28 is added based on whether or not the in-vehicle device mounted on the vehicle 10 and driven by the engine 14 is driven, and whether or not the exhaust gas purifying device that purifies the exhaust gas discharged from the engine 14 is regenerated. Calculate the injection time. When the fuel injection amount based on this additional injection time is injected, the driving force of the in-vehicle device is supplemented or the exhaust gas purification device is regenerated. Next, the control unit 28 calculates the fuel injection amount Qx based on the total value of the reference injection time and the additional injection time for each sampling cycle ts.

The control unit 28 is not limited to this configuration as long as it can acquire the fuel injection amount Qx actually injected in the engine 14. The control unit 28 may calculate the reference injection time from the internal pressure, volumetric efficiency, and required air-fuel ratio of the intake manifold (not shown), or from the intake air amount and the engine speed Nx. Examples of the in-vehicle device include an air compressor and a motor generator. As an exhaust gas purification device, a collection filter that collects particulate matter in the exhaust gas can be exemplified.

The position sensor 24 is a device that functions as a part of the parameter acquisition means, and detects the lever position Px required by the driver by electrically detecting the position of the shift lever 23 operated by the driver of the vehicle 10. To do. The position sensor 24 detects the gear ratio ix of the transmission 16 according to the lever position Px for each sampling cycle ts. Examples of the lever position Px include a parking position (P position), a reverse position (R position), a neutral position (N position), and a forward position (D range). As the forward position, for example, a plurality of 1st to 6th speeds are set. Each forward position is set with a gear ratio ix that decreases as the number of gears increases from the first gear. When the transmission 16 is composed of an AMT, instead of the position sensor 24, one having a function of reading the shift stage of the transmission 16 controlled by the control unit 28 may be used. Further, when the gear ratio ix of the transmission 16 is acquired from the control signal of the control unit 28, the gear ratio ix can be obtained based on the vehicle speed vx and the engine rotation speed Nx.

The vehicle speed sensor 26 is a device that functions as a part of the parameter acquisition means, reads a pulse signal proportional to the rotation speed of the propeller shaft 17, and calculates the vehicle speed vx for each sampling cycle ts by the vehicle speed calculation process (not shown) of the control device 20. It is a sensor to acquire. Since the vehicle speed sensor 26 acquires the vehicle speed vx based on the pulse signal proportional to the rotation speed, the acquired vehicle speed vx is not negative but a value of zero or more. As the vehicle speed sensor 26, a sensor that acquires the vehicle speed vx from the rotation speeds of the output shaft, the driving wheels 19, the driven wheels, and the like (not shown) of the transmission 16 may be used. When a sensor that acquires the vehicle speed vx from the rotation speeds of the driving wheels 19, the driven wheels, and the like is used, it is preferable to acquire the rotation speeds of each of the pair of left and right wheels and use the average value as the vehicle speed vx.

The acceleration sensor 27 is a device that functions as a part of the parameter acquisition means, and operates by an acceleration component accompanying a speed change in the front-rear direction of the vehicle 10 and a gravitational acceleration component accompanying a posture change of the vehicle 10. The acceleration sensor 27 is a sensor that acquires an acceleration component parallel to the road surface, that is, an acceleration Gx in the front-rear direction of the vehicle 10, for each sampling cycle ts. Examples of the acceleration sensor 27 include a mechanical displacement measurement method, an optical method, and a semiconductor method.

As illustrated in FIGS. 3 and 4, in this embodiment, the vehicle weight calculation unit 31 has a parameter acquisition unit 32, an estimation unit 33, and a maintenance unit 34 as each functional element. Each functional element of the vehicle weight calculation unit 31 is stored as a program in the internal storage device, but each functional element may be configured by individual hardware.

Note that FIG. 3 shows a case where “1” is output as a binary signal from the check block 34a, which will be described later, and the timer is turned off. FIG. 4 shows a case where the check block 34a outputs a binary signal “1”. "0" is output, indicating a state in which the timer is turned on by the timer block 34g.

The parameter acquisition unit 32 functions as a parameter acquisition means, and the detection values of the control unit 28 and each sensor are input. The parameter acquisition unit 32 has a function of outputting the first parameter Φx and the second parameter Φy to the estimation unit 33 and the drive torque Tw to the maintenance unit 34 as parameters that change while the vehicle 10 is traveling in each sampling cycle ts. It is an element. The parameter acquisition unit 32 has a first parameter calculation block 32a, a second parameter calculation block 32b, and an engine torque calculation block 32c.

The first parameter calculation block 32a is a functional element in which the acceleration Gx is input and the first parameter Φx is calculated. The second parameter calculation block 32b is a functional element for calculating the second parameter Φy by inputting the vehicle speed vx, the gear ratio ix of the transmission 16, and the engine torque Te. The engine torque calculation block 32c is a functional element that calculates the engine torque Te that is actually output from the engine 14 by inputting the engine rotation speed Nx and the fuel injection amount Qx.

The estimation unit 33 functions as an estimation means, and the first parameter Φx and the second parameter Φy are input, and the estimation unit 33 is based on them and the previous value mx (k-1) estimated immediately before in the sampling cycle ts. It is a functional element that outputs the estimated value mx (k) estimated by using the smoothing process. The estimation unit 33 is composed of an RLS estimation block. The RLS estimation block updates the variables in the estimation operation every sampling period ts. That is, the RLS estimation block stores the previous value mx (k-1), the covariance matrix P (k-1), and the gain K (k-1) calculated by the RLS algorithm when a new parameter is input. It is in the state of being.

The maintenance unit 34 functions as a maintenance means, and is interposed between the parameter acquisition unit 32 and the estimation unit 33. The maintenance unit 34 is a functional element that inputs the parameters acquired by the parameter acquisition unit 32 to the estimation unit 33 based on the determination result for each sampling cycle ts. In other words, the estimation unit 33 permits estimation based on the determination result. And prohibited functional elements. Specifically, the maintenance unit 34 selects whether or not each parameter is input and the first parameter Φx and the second parameter Φy are output to the estimation unit 33 based on the drive torque Tw. The maintenance unit 34 has a check block 34a, an assertion block 34b, a switch block 34c, a rate of change acquisition block 34d, a trigger block 34e, and a timer block 34f.

The check block 34a inputs the rate of change ΔTw output from the rate of change acquisition block 34d for each sampling cycle ts, and determines whether or not vibration due to twisting has occurred in the propeller shaft 17 based on the rate of change ΔTw. It is a functional element. Specifically, the check block 34a determines whether or not vibration is generated depending on whether or not the rate of change ΔTw is within the preset threshold value ΔTa or less. The check block 34a outputs "1" (a signal indicating true) as a binary signal when no vibration is generated. On the other hand, the check block 34a outputs "0" (a signal indicating false) as a binary signal when vibration occurs.

The assertion block 34b receives each parameter and a binary signal output from the switch block 34c, and determines whether or not to output each parameter to the estimation unit 33 based on the binary signal for each sampling cycle ts. It is a functional element to be used. Specifically, the assertion block 34b allows the input of the first parameter Φx and the second parameter Φy to the estimation unit 33 when the binary signal is “1”. On the other hand, when the binary signal is "0", the input of the first parameter Φx and the second parameter Φy to the estimation unit 33 is prohibited.

The switch block 34c outputs "0" as a binary signal when each binary signal is input and "0" is input as a binary signal by the timer block 34g, and checks in other cases. It is a functional element that outputs a binary signal output from the block 34a.

The change rate acquisition block 34d is a functional element in which the drive torque Tw output from the parameter acquisition unit 32 is input for each sampling cycle ts, the change rate ΔTw of the drive torque Tw is calculated, and the drive torque Tw is output to the check block 34a. ..

The trigger block 34e is a functional element in which a binary signal output from the check block 34a is input every sampling cycle ts, and when the binary signal is “0”, “1” is output as the binary signal.

In the timer block 34f, the binary signal output from the trigger block 34e is input, and when the binary signal is "1", the timer is turned on and every sampling cycle ts until the preset time ta elapses. It is a functional element that outputs "0" as a binary signal.

Next, the estimation calculation of the estimated value mx (k) by the estimation unit 33 of this embodiment will be described. Based on each parameter and the previous value mx (k-1), the estimation unit 33 regards the equation of motion in the front-rear direction of the vehicle 10 as a transfer function, and uses an adaptive algorithm as a smoothing process to estimate the value mx ( K-1) is estimated. The RLS algorithm (sequential least squares algorithm) is used as the adaptive algorithm.

The equation of motion of the vehicle 10 in the front-rear direction is expressed by the following mathematical formula (1). In the formula (1), vx'is the derivative value obtained by time-differentiating the vehicle speed vx, Tw is the drive torque transmitted to the drive wheels 19, rw is the wheel diameter of the drive wheels 19, and Δmx is the mass equivalent to the rotating portion described later. , B is a constant, g is the gravitational acceleration, and μ is the rolling resistance coefficient. The constant B is a constant obtained by multiplying "0.5", the air density ρ, the front projected area Af of the vehicle 10, and the air resistance coefficient Cd. The wheel diameter rw, the constant B, and the rolling resistance coefficient μ are obtained as values unique to the vehicle 10.

By modifying the above formula (1), the weight mx of the vehicle 10 is expressed by the following formula (2).

The above formula (2) can be regarded as a transfer function in which the first parameter Φx is an input value, the second parameter Φy is an output value, and the estimated value mx is a variable. Therefore, the transfer function (Φy (k) = Φx (k) · mx (k)) is self-adapted according to the RLS algorithm to estimate the estimated value mx (k). The estimated value mx (k) is expressed by the following mathematical formulas (3) to (5). In the following formula, mx (k-1) is the previous value estimated immediately before the sampling period ts, K (k) is the gain calculated by the RLS algorithm, and P (k) is the covariance. The covariance matrix, I indicates the identity matrix, and " ^T " indicates the transposed matrix.

If the initial value P (0) of the covariance matrix P (k) is determined, the covariance matrix P (k) is based on the above equation (5) and the equation (4) is used based on the first parameter Φx. The gain K (k) calculated by the RLS algorithm can be calculated respectively. That is, every time the first parameter Φx and the second parameter Φy are newly obtained, the covariance matrix P (k) and the gain K (k) are newly updated. Then, the estimated value mx (k) can be calculated by a method of correcting the previous value mx (k-1) estimated immediately before based on them and the mathematical formula (3).

The initial value P (0) is represented by the product of the constant α and the identity matrix I. A value of about 1000 is usually used as the constant α, but when the noise is large, the constant α should be set small, and this constant α is determined by the magnitude of the noise. As the initial value m (0), for example, the vehicle weight when the vehicle is empty excluding the driver and the load, the gross vehicle weight when the maximum load is applied, or the average value of the estimated values mx (k) may be used.

When the covariance matrix P (k) becomes large, the estimated value mx (k) moves away from the true value, and when the covariance matrix P (k) converges small, the estimated value mx (k) approaches the true value.

In this way, by regarding the above mathematical formula (2) as a transfer function and estimating the estimated value mx (k) by the adaptive algorithm, the estimated value mx (k) can be sequentially smoothed. This is advantageous for speeding up convergence to the true value and improving robustness against noise, disturbance, or changes in the statistical properties of the detected values of each sensor, and can reduce estimation errors. Along with this, the weight of the vehicle 10 can be estimated with high accuracy.

In this embodiment, the estimated value mx (k) can be obtained from the above mathematical formulas (3) to (5) by using the RLS algorithm among the adaptive algorithms. This is advantageous for online estimation, and the estimated value mx (k) can be calculated in real time. Further, as compared with the method of removing noise by a low-pass filter with respect to the detected value acquired by each sensor, it is advantageous for ensuring the responsiveness of estimating the weight of the vehicle 10.

In addition, the previous values mx (k-1), the covariance matrix P (k-1), and the gain K (k-1) need only be updated for each sampling period ts, and are stored in the internal storage device of the control device 20. You can minimize the number to be made. Therefore, the storage required for estimation is compared with the method by offline estimation (batch processing estimation) in which the internal storage device of the control device 20 must secure an infinite storage area for an uncertain traveling period of the vehicle 10. It is advantageous for capacity reduction. The offline estimation referred to here can be exemplified by a batch processing least squares method, a method of calculating the average value of all estimated values mx (0) to mx (k), and the like.

Further, by using the RLS algorithm, the estimated value mx (k) can be calculated for each sampling period ts. This is advantageous for real-time estimation as compared with the method of estimating when the state of the vehicle 10 (for example, gear ratio ix or drive torque Tw) changes or when the vehicle travels a predetermined distance.

Next, the vehicle weight estimation method of the present invention will be described as each function of the vehicle weight calculation unit 31 with reference to the flow chart of FIG. The following vehicle weight estimation method is started when the control device 20 of the vehicle 10 is energized, and is repeatedly performed every sampling cycle ts to estimate the weight of the vehicle 10 in real time. That is, processing from the start to the return is performed in one sampling cycle ts. Then, when the control device 20 loses power, it ends.

When the vehicle starts, the vehicle weight calculation unit 31 uses the function of the parameter acquisition unit 32 to perform the vehicle 1
Acquire a parameter that changes during traveling of 0 (S110). The parameters are the first parameter Φx, the second parameter Φy, and the drive torque Tw.

Specifically, the parameter acquisition unit 32 acquires those parameters from the detection values detected by the control unit 28 and each sensor. First, the control unit 28 determines the fuel injection amount Qx, the position sensor 24 determines the gear ratio ix of the transmission 16, the rotation speed sensor 25 determines the engine rotation speed Nx, the vehicle speed sensor 26 determines the vehicle speed vx, and the acceleration sensor 27 determines the acceleration Gx. Get each.

Next, the first parameter calculation block 32a calculates the first parameter Φx shown in the following mathematical formula (6) by each block.

As described above, the acceleration Gx is an acceleration component parallel to the road surface, which is a combination of an acceleration component associated with a speed change of the vehicle 10 in the front-rear direction and a gravitational acceleration component associated with a posture change of the vehicle 10. That is, the acceleration Gx is a value obtained by adding the differential value vx'and the gravitational acceleration component g · sin β. Therefore, the mathematical formula (6) is synonymous with the numerator of the above mathematical formula (2).

As the variables of the first parameter Φx, as shown in the above formula (2), instead of the acceleration Gx, the differential value vx'of the vehicle speed vx and the gravitational acceleration component based on the road surface gradient on which the vehicle 10 is traveling You may use g · sinβ. In this case, instead of the acceleration sensor 27, it is preferable to use a vehicle speed sensor 26, a gradient sensor that acquires the road surface gradient on which the vehicle 10 is traveling, and a functional element that calculates the road surface gradient.

Next, the engine torque calculation block 32c calculates the actual engine torque Te output from the engine 14 based on the fuel injection amount Qx and the engine rotation speed Nx.

As illustrated in FIG. 6, the engine torque Te output from the engine 14 has a positive relationship with each of the engine rotation speed Nx and the fuel injection amount Qx, and the engine rotation speed Nx is fast and the fuel injection amount Qx. The larger the, the larger. This map data is obtained in advance by experiments and tests, and is stored in the engine torque calculation block 32c, which is a data block.

In this embodiment, the engine torque Te is calculated from the relationship between the engine rotation speed Nx and the fuel injection amount Qx, but the accelerator opening Ax acquired by the accelerator opening sensor 22 may be used instead of the fuel injection amount Qx. , Other acquisition methods may be used.

Next, the second parameter calculation block 32b calculates the drive torque Tw transmitted to the drive wheels 19 by using the following mathematical formula (7). In formula (7), if indicates the gear ratio of the differential gear 18, and η indicates the transmission efficiency that differs depending on the gear ratio. The drive torque Tw may be obtained by using a torque sensor or by another method.

Next, the second parameter calculation block 32b calculates the rotating portion equivalent mass Δmx by the lookup table block 32d.

The mass corresponding to the rotating portion Δmx is a value determined according to the gear ratio ix, which is a variable. The lookup table block 32d is set with a plurality of masses Δmx corresponding to a plurality of rotating portions for each gear ratio ix, and the one corresponding to the gear ratio ix is selected. The mass corresponding to the rotating portion Δmx may be calculated from the relationship with the vehicle weight when the vehicle is empty, the gear ratio ix, and a predetermined coefficient.

Next, the second parameter calculation block 32b calculates the second parameter Φy shown in the following mathematical formula (8) by each block.

In this embodiment, the second parameter Φy is shown by the above mathematical formula (8), but the friction torque Tf acting on the engine 14, the clutch 15, the transmission 16, the differential gear 18, and the like may be considered. In this case, the value obtained by subtracting the friction torque Tf from the drive torque Tw may be divided by the wheel diameter rw of the drive wheel 19. Considering the friction torque Tf, it is advantageous for improving the estimation accuracy.

When each parameter is acquired as described above, the vehicle weight calculation unit 31 calculates the rate of change ΔTw by the function of the rate of change acquisition block 34d of the maintenance unit 34 (S120). Specifically, in the rate of change acquisition block 34d, the difference between the drive torque Tw (k) output from the parameter acquisition unit 32 and the previous drive torque Tw (k-1) in which the sampling cycle ts is delayed by one is changed. It is output to the check block 34a as a rate ΔTw. The rate of change ΔTw may be an absolute value, and if it is set to an absolute value, it can correspond to both the case where the rate of change ΔTw becomes positive and the case where it becomes negative. Further, the difference from the previous drive torque Tw (k−N) delayed by N or more may be output to the check block 34a as the rate of change ΔTw.

Next, the vehicle weight calculation unit 31 determines whether or not the rate of change ΔTw is within the threshold value ΔTa or not by the function of the check block 34a of the maintenance unit 34 (S130).

The threshold value ΔTa is set to a value that can identify that vibration due to twisting has occurred in the propeller shaft 17. When the rotation direction of the propeller shaft 17 is positive and the direction opposite to the rotation direction is negative, the threshold value ΔTa is set to a positive value.

In this embodiment, the threshold value may be different depending on whether the rate of change ΔTw is positive or the rate of change ΔTw is negative. The threshold value when the rate of change ΔTw becomes negative may be obtained in advance by experiments or the like, or may be set based on the brake torque when the brake torque can be obtained during braking.

When it is determined in this step that the rate of change ΔTw is within the threshold value ΔTa, the vehicle weight calculation unit 31 determines whether or not the timer of the timer block 34f is turned off by the function of the switch block 34c of the maintenance unit 34. Judgment (S140). Specifically, in the switch block 34c, the binary signal from the timer block 34f is not input, and the switch switches to the output of the binary signal of the check block 34a.

If it is determined in this step that the timer is off, the vehicle weight calculation unit 31 inputs the first parameter Φx and the second parameter Φy to the estimation unit 33 by the function of the assertion block 34b of the maintenance unit 34. Specifically, in the assertion block 34b, when the rate of change ΔTw is within the threshold value ΔTa, the binary signal “1” output from the check block 34a is input via the switch block 34c. The first parameter Φx and the second parameter Φy are output to the estimation unit 33.

Next, the vehicle weight calculation unit 31 estimates the estimated value mx (k) by the above-mentioned estimation method of the estimation unit 33 (S150). Next, the vehicle weight calculation unit 31 outputs the input estimated value mx (k) as an output value mx (S160). Then return to the start.

On the other hand, if it is determined in the above step that the rate of change ΔTw exceeds the threshold value ΔTa, the vehicle weight calculation unit 31 turns on the timer of the timer block 34f by the function of the trigger block 34e (S170). When the timer of the timer block 34f is turned on in this step, "0" is input to the switch block 34c as a binary signal, and the switch switches to the output of "0" which is a binary signal.

Next, the vehicle weight calculation unit 31 prohibits the output of the first parameter Φx and the second parameter Φy by the function of the assertion block 34b of the maintenance unit 34. Specifically, in the assertion block 34b, when the rate of change ΔTw exceeds the threshold value ΔTa and the timer is turned on, “0”, which is a binary signal output from the switch block 34c, is input and the first parameter is The output of Φx and the second parameter Φy is prohibited.

That is, since the vehicle weight calculation unit 31 is prohibited from inputting the first parameter Φx and the second parameter Φy to the estimation unit 33 by the function of the maintenance unit 34, the sampling cycle ts is delayed by one. The previous value mx (k-1) is output as the output value mx as the pre-estimated value (S180).

Next, the vehicle weight calculation unit 31 adds (counts) the sampling cycle ts to the elapsed time t (k) since the timer was turned on by the function of the timer block 34f of the maintenance unit 34 (S190). Next, the vehicle weight calculation unit 31 determines whether or not the elapsed time t (k) is equal to or greater than the preset time ta by the function of the timer block 34f of the maintenance unit 34 (S200).

The time ta is set to a value that can be determined from the time when the propeller shaft 17 vibrates due to the twist until the twist is eliminated and the vibration stops. The time ta is an eigenvalue of the vehicle 10 and varies depending on the axial length of the propeller shaft 17 and the like. The time ta may be determined in advance by experiments or tests.

If it is determined in this step that the elapsed time t (k) is less than the time ta, the process returns to the start. On the other hand, when it is determined that the elapsed time t (k) is equal to or longer than the time ta, the vehicle weight calculation unit 31 turns off the timer by the function of the timer block 34f (S210). Then return to the start.

According to the above estimation method, while the propeller shaft 17 is vibrated due to twisting, the weight of the vehicle 10 is the previous value mx (previous estimated value) estimated based on the parameters acquired before the vibration occurs. Maintain k-1).

As illustrated in FIG. 7, the estimated value mx (k) is output as the weight of the vehicle 10 for each sampling cycle ts until the time t (0). When the rate of change ΔTw exceeds the threshold value ΔTa at time t (0), the timer operates. At this time, vibration due to twisting occurs in the propeller shaft 17, and the rotation speed of the propeller shaft 17 fluctuates (the positive and negative rotation angular velocities are repeatedly switched). Then, when the time ta or more elapses after the timer is turned on at the time t (0), the timer is turned off. From this time t (0) to time t (n), the maintenance unit 34 holds the previous value mx (k-1), which is an estimated value before occurrence, and outputs it as the weight of the vehicle 10. After the time t (a), the estimated value mx (k) is output as the weight of the vehicle 10 for each sampling cycle ts.

In this way, from the time when the rate of change ΔTw of the drive torque Tw exceeds the threshold value ΔTa to the time when the time ta elapses, it is considered that the propeller shaft 17 is vibrating due to twisting, and the vibration is regarded as being generated. The previous value mx (k-1) is output as the weight of the vehicle 10 as the pre-occurrence estimated value estimated before the occurrence of. Therefore, by outputting the previous value mx (k-1) until the error due to vibration is reduced, a constant value can be maintained as the weight of the vehicle 10. This is advantageous in reducing the estimation error when vibration due to twisting occurs in the propeller shaft 17, and the weight of the vehicle 10 can be estimated with high accuracy.

Further, by adopting a method of comparing the rate of change ΔTw and the threshold value ΔTa, the calculation load of the vehicle weight calculation unit 31 can be suppressed low. Further, it is also advantageous in ensuring responsiveness as compared with a method of performing noise removal processing such as a low-pass filter on parameters that change variously depending on the type of the vehicle 10 and the traveling state.

In particular, in this embodiment, the check block 34a and the assertion block 34b of the maintenance unit 34 function as an assertion check for the estimation calculation process of the estimated value mx (k). That is, when the rate of change ΔTw exceeds the threshold value ΔTa, the first parameter Φx and the second parameter Φy are regarded as negates and are not input to the estimation unit 33. On the other hand, when the rate of change ΔTw is within the threshold value ΔTa, the first parameter Φx and the second parameter Φy are regarded as asserted and input to the estimation unit 33. As a result, if each parameter is valid, the estimation unit 33 can estimate the estimated value mx (k), and if each parameter is invalid, the estimation unit 33 can prohibit the estimation.

In this way, when the smoothing process is performed using the RLS algorithm based on the first parameter Φx and the second parameter Φy and the previous value mx (k-1), the assertion check is performed to perform the estimated value mx (k-1). ) Is advantageous for reducing the estimation error when the smoothing process is performed, and the weight of the vehicle 10 can be estimated with high accuracy. In addition, it is also advantageous for increasing the speed of convergence to the true value m when the estimated value mx (k) is smoothed, and the estimated value mx (k) can be quickly converged to the true value m.

In this embodiment, since the rate of change ΔTw of the drive torque Tw and the threshold value ΔTa are compared, the estimation of the estimation unit 33 can be prohibited before the propeller shaft 17 actually vibrates due to twisting and the estimation error becomes large. .. This is advantageous in reducing the estimation error of the previous value mx (k-1), and the weight of the vehicle 10 can be estimated with high accuracy.

As described above, in this embodiment, the rate of change ΔTw is used as a numerical value relating to the rotational fluctuation of the propeller shaft 17 due to vibration, but any numerical value that can determine whether or not vibration due to twisting occurs in the propeller shaft may be used. For example, instead of the rate of change ΔTw, a differential value obtained by time-differentiating the drive torque Tw may be used. Further, a torque sensor capable of directly acquiring the rotational fluctuation of the propeller shaft 17 may be used, and the detected value of the torque sensor may be used. However, by calculating the difference between the drive torque Tw (k) and the previous drive torque Tw (k-1) as the rate of change ΔTw, the calculation load can be reduced as compared with the case where the differential value is used. In addition, the cost of estimation can be reduced as compared with the case of using a torque sensor.

In this embodiment, it is considered that the propeller shaft 17 is oscillated by twisting until the timer is turned on after the rate of change ΔTw exceeds the threshold value ΔTa and the timer is turned off after the lapse of time ta. are doing. As a result, the end of vibration can be determined without using complicated calculations, which is advantageous in reducing the calculation load. As described above, when a torque sensor is used, the start and end of vibration can be directly determined by the torque sensor.

The larger the rate of change ΔTw, the greater the twist of the propeller shaft 17, and the longer the time required for the vibration to disappear. The time required for the vibration to be eliminated has a positive relationship with the rate of change ΔTw, and the larger the value of the rate of change ΔTw, the greater the time. Therefore, the time ta may be changed based on the rate of change ΔTw.

In this embodiment, the threshold value ΔTa is set to a value that can identify that vibration due to twisting has occurred in the propeller shaft 17. Vibration due to twisting frequently occurs when the vehicle 10 starts or suddenly accelerates. Therefore, the threshold value ΔTa may be changed according to the driving state of the vehicle 10.

In this embodiment, the vehicle 10 has been described as an example of a large vehicle such as a truck, but the vehicle weight estimation device 30 of the present invention can be applied to a bus, an ordinary vehicle, and a towing vehicle (tractor), and can be applied to the types of vehicles 10. Is not limited. That is, as the power source of the vehicle 10, a motor generator can be exemplified in addition to the engine 14.

In this embodiment, the estimation unit 33 does not define the conditions for estimating the estimated value mx (k), but it is preferable to estimate the estimated value mx (k) when the following conditions are satisfied. As a condition, when the clutch 15 is completely engaged in a state where the brake is not activated, the differential value vx'of the vehicle speed vx becomes equal to or more than a preset threshold value, and the drive torque Tw becomes equal to or more than the threshold value. .. In addition to the rate of change ΔTw, the estimation accuracy can be improved by estimating the estimated value mx (k) by the RLS algorithm only when such a condition is satisfied.

In this embodiment, an example in which the RLS algorithm is used as the estimation calculation of the estimated value mx (k) has been described, but the estimation unit 33 only needs to be able to estimate the weight of the vehicle 10, and the estimation calculation is not limited to this. For example, instead of the RLS algorithm, an LMS algorithm, an NLMS algorithm, or the like may be used as the adaptive algorithm. Further, the value obtained by dividing the second parameter Φy by the first parameter Φx may be output as the estimated value mx (k) without using the adaptive algorithm. Further, the average value of all the estimated estimated values mx (0) to the estimated values mx (k) may be output. Further, as a parameter that changes while the vehicle is running, a parameter that estimates the weight of the vehicle may be used based on the torque input to the transmission before and after the shift and the amount of change in the number of revolutions output from the transmission. .. Further, when the vehicle 10 is equipped with an air suspension, a method based on a change in the vehicle 10 in the vertical direction may be used. Further, the tentative estimated value Mx may be a value obtained by adding the weight of the body 13 due to the change in the load capacity to the value acquired by a weight sensor such as a load cell and the weight of the vehicle when the vehicle is empty. In any case, as in this embodiment, it is desirable to prohibit the estimation by assuming that the estimation error is large while the propeller shaft 17 is vibrating due to twisting.

Further, in the above-described embodiment, an example in which the vehicle weight estimation device 30 is composed of the vehicle weight calculation unit 31 and each sensor has been described, but the present invention is not limited thereto. For example, the vehicle weight estimation device 30 may be composed of one sensor that functions as a parameter acquisition means and an estimation means, and hardware that functions as a maintenance means.

In addition to prohibiting the estimation by the estimation unit 33, the maintenance unit 34 may be configured to prohibit the output of the estimated value mx (k) estimated by the estimation unit 33. For example, when the binary signal from the timer block 34f is "1", the estimated value mx (k) is output, while when the binary signal is "0", the previous value mx (k-1) is output. It may be configured to output. However, with such a configuration, the estimation by the estimation unit 33 is not prohibited as compared with the above-described embodiment.

10 Vehicle 24 Position sensor 25 Rotational speed sensor 26 Vehicle speed sensor 27 Acceleration sensor 28 Control unit 30 Vehicle weight estimation device 31 Vehicle weight calculation unit 32 Parameter acquisition unit 33 Estimating unit 34 Maintenance unit Φx First parameter Φy Second parameter mx (k) Estimated value mx (k-1) Previous value (estimated value before occurrence)

Claims (7)

A power source, a transmission that shifts and outputs the rotational power input from this power source, a propeller shaft that transmits the changed rotational power, and a differential gear that distributes the transmitted rotational power to each drive wheel. In a vehicle weight estimation device that estimates the weight of a vehicle that has
A parameter acquisition means for acquiring parameters that change while the vehicle is running, and
An estimation means in which parameters acquired by this parameter acquisition means are input and an estimated value of the weight of the vehicle estimated based on the parameters is output.
While the propeller shaft is vibrated due to twisting, the propeller shaft is provided with a maintenance means for maintaining the pre-occurrence estimated value estimated by the estimating means before the vibration occurs as the weight of the vehicle. Vehicle weight estimation device. The parameter acquisition means acquires a numerical value relating to the rotation fluctuation of the propeller shaft due to the vibration, and the numerical value relating to the rotation fluctuation is input to the maintenance means.
The vehicle weight estimation device according to claim 1, wherein the maintenance means determines the start of the vibration based on a numerical value related to the rotation fluctuation. The numerical value related to the rotation fluctuation is the rate of change of the drive torque transmitted to the drive wheels.
The vehicle weight estimation device according to claim 2, wherein the vibration is set when the rate of change exceeds a preset threshold value. The vehicle weight estimation device according to claim 3, wherein the end of the vibration is set when a preset time elapses after the rate of change exceeds the threshold value. The vehicle weight estimation device according to claim 3 or 4, wherein the rate of change is a difference between the drive torques calculated for each predetermined sampling cycle. The estimation means is configured to output the parameter and the estimated value estimated by using the smoothing process based on the previous value estimated before acquiring the parameter.
The maintenance means is interposed between the parameter acquisition means and the estimation means, and the maintenance means prohibits the input of the parameters acquired by the parameter acquisition means to the estimation means while the vibration is generated. The vehicle weight estimation device according to any one of claims 1 to 5, which is configured to maintain the pre-occurrence estimation value. In a vehicle weight estimation method that estimates the weight of a vehicle by shifting the rotational power input from a power source by a transmission and distributing the rotational power transmitted via a propeller shaft to each drive wheel by a differential gear.
Acquire parameters that change while the vehicle is running,
Based on the parameter, it is determined whether or not the propeller shaft is vibrated due to twisting.
A vehicle weight estimation method, characterized in that, while the vibration is generated, the pre-occurrence estimated value estimated based on the parameters acquired before the vibration occurs is maintained as the weight of the vehicle.