JP2017226263A - Road surface gradient estimation device and road surface gradient estimation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a road surface gradient estimation device and a road surface gradient estimation method which can estimate with high accuracy road surface gradients by reducing estimate errors at the time of starting a vehicle.SOLUTION: A road surface gradient estimation device 30 comprises a vehicle speed sensor 26, an acceleration sensor 27 and a road surface gradient calculation portion 31. The road surface gradient calculation portion 31 is constituted to comprise an estimation portion 32 that estimates road surface gradients and an output portion 33 that outputs an estimate value θ(x-1) before starting a vehicle, estimated by the estimation portion 32 before starting the vehicle 10 until the vehicle travels in a direction corresponding to an operation command at the time of starting the vehicle 10.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a road surface gradient estimation device and a road surface gradient estimation method, and more particularly to a road surface gradient estimation device and a road surface gradient estimation method for estimating a road surface gradient with high accuracy.

  An apparatus that sequentially detects a road surface gradient using a gradient sensor has been proposed (see, for example, Patent Document 1). This device maintains the road surface gradient detected by the gradient sensor immediately before starting the vehicle until a predetermined time has elapsed since the vehicle started, so that the output value of the gradient sensor due to the vehicle shake that occurs when the vehicle starts The influence on the road surface gradient is avoided and the detection error of the road surface gradient is reduced.

JP 2007-127155 A

  However, in the above apparatus, the period during which the road surface gradient value with a small error immediately before the vehicle starts is used only when the vehicle starts, and the detection value detected by the gradient sensor is used immediately after the vehicle starts. Therefore, immediately after the vehicle tries to start in the direction of climbing up the slope according to the driver's operation command, if the vehicle slips in the direction of descending against the operation command, it is A large error occurs in the detected value.

  The present invention has been made in view of the above, and an object of the present invention is to provide a road surface gradient estimation device and a road surface gradient estimation method that reduce an estimation error when starting a vehicle and estimate a road surface gradient with high accuracy. Is to provide.

  The road surface gradient estimation device of the present invention that achieves the above object includes vehicle speed acquisition means for acquiring the vehicle speed of the vehicle, acceleration acquisition means for acquiring the longitudinal acceleration of the vehicle, vehicle speed acquired by the vehicle speed acquisition means, and The acceleration acquired by the acceleration acquisition means is input, and the estimation means for outputting the estimated value obtained by estimating the road surface gradient on which the vehicle is traveling based on the vehicle speed and acceleration, the estimated value estimated by the estimating means Until the vehicle travels in the direction according to the operation command at the time of starting, the output means for outputting the pre-start estimated value estimated by the estimating means before the vehicle starts as the road surface gradient It is characterized by comprising.

  The road gradient estimation method of the present invention that achieves the above object acquires the vehicle speed of the vehicle and the acceleration in the longitudinal direction of the vehicle, and the road gradient of the road on which the vehicle is traveling based on the acquired vehicle speed and acceleration. In the road surface gradient estimation method for estimating an estimated value, it is determined whether or not the vehicle has traveled in a direction according to an operation command at the time of starting, and until the vehicle has traveled in a direction according to the operation command. The interval is a method characterized in that a pre-start estimated value estimated before the vehicle starts is used as a road surface gradient.

According to the present invention, since the vehicle starts and travels in the direction according to the operation command at the time of starting, the pre-start estimated value estimated before the vehicle starts is output as the road surface gradient. Until the error of the estimated value decreases, a constant value can be maintained as the road surface gradient by the estimated value before starting. This avoids the influence of vibration and slipping when the vehicle starts, is advantageous for reducing the estimation error when starting the vehicle, and can estimate the road surface gradient with high accuracy.

It is explanatory drawing which illustrates 1st embodiment of the road surface gradient estimation apparatus of this invention. It is a block diagram which illustrates the control device of FIG. It is a block diagram which illustrates the road surface gradient calculating part of FIG. It is a flowchart which illustrates 1st embodiment of the road surface gradient estimation method of this invention. It is a block diagram which illustrates the road surface gradient calculating part of 2nd embodiment of the road surface gradient estimation apparatus of this invention. It is a flowchart which illustrates 2nd embodiment of the road surface gradient estimation method of this invention.

  Embodiments of a road surface gradient estimation apparatus and a road surface gradient estimation method of the present invention will be described below. In the following, the road slope of the uphill road is positive, and the road slope of the downhill road is negative.

  The road surface gradient estimation device 30 of the first embodiment illustrated in FIGS. 1 to 3 is a device that is mounted on the vehicle 10 and estimates the road surface gradient on which the vehicle 10 is traveling.

  As illustrated in FIG. 1, in the vehicle 10 on which the road surface gradient estimation device 30 is mounted, a cab 12 is disposed on the front side of the chassis 11, and a body 13 is disposed 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 changed by the transmission 16 is transmitted to the differential gear 18 through the propeller shaft 17 and is distributed as a driving force to the pair of driving wheels 19 as rear wheels.

  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 from the depression amount of the accelerator pedal 21 and a position sensor 24 that detects the position of the shift lever 23. The chassis 11 is provided with an engine speed sensor 25, a vehicle speed sensor 26, and an acceleration sensor 27 that detect the speed of a crankshaft (not shown) of the engine 14.

  The control device 20 is hardware that includes 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, a vehicle weight calculation unit 29 that calculates the vehicle weight of the vehicle 10, and the vehicle 10 traveling. A road surface gradient calculating unit 31 for calculating the road surface gradient is provided as each functional element. 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 road surface gradient estimation device 30 according to the present invention includes a road surface gradient calculation unit 31, a position sensor 24, a vehicle speed sensor 26, and an acceleration sensor 27. The detection values of these sensors are input and based on the detection values. The calculated result is output as an output value θx of the road surface gradient. The road surface gradient calculation unit 31 functions as vehicle speed acquisition means, acceleration acquisition means, estimation means, and output means using these sensors.

  The position sensor 24 is a device that functions as a part of the output means, and detects the shift position requested by the driver by electrically detecting the position of the shift lever 23 operated by the driver of the vehicle 10. Examples of the shift position include a parking position (P position), a reverse position (R position), a neutral position (N position), and a forward position (D range). As the position sensor 24, a sensor having a function of reading the shift stage of the transmission 16 controlled by the control unit 28 as a shift position when the transmission is configured by an AMT may be used.

  The vehicle speed sensor 26 is a device that functions as vehicle speed acquisition means. In this embodiment, the vehicle speed sensor 26 reads a pulse signal proportional to the rotational speed of the propeller shaft 17 and acquires it as the vehicle speed vx by the vehicle speed calculation process of the control device 20. . 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 has a value of zero or more. As the vehicle speed sensor 26, a sensor that acquires the vehicle speed vx from the rotational speed of an output shaft (not shown) of the transmission 16, the drive wheel 19, the driven wheel, or the like may be used. In addition, when using the sensor which acquires vehicle speed vx from rotational speeds, such as a driving wheel 19 and a driven wheel, it is good to acquire each rotational speed of a pair of left and right wheels, and let the average value be the vehicle speed vx. The vehicle speed sensor 26 that obtains the vehicle speed vx from the rotational speed of the wheel is not affected by the rotational speed fluctuation of the propeller shaft 17 at the time of starting or accelerating, and is therefore preferably used when the rotational speed fluctuation of the propeller shaft 17 is large.

  The acceleration sensor 27 is a device that functions as an acceleration acquisition unit. In this embodiment, the acceleration sensor 27 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 sensor acquires an acceleration component parallel to the road surface obtained by combining them, that is, an acceleration Gx in the longitudinal direction of the vehicle 10. Examples of the acceleration sensor 27 include a mechanical displacement measurement method, an optical method, and a semiconductor method.

  As illustrated in FIG. 3, in this embodiment, the road surface gradient calculation unit 31 includes an estimation unit 32 and an output unit 33 as each functional element. Each functional element of the road surface gradient calculation unit 31 is stored as a program in the internal storage device, but each functional element may be configured by individual hardware.

  The estimation unit 32 functions as an estimation unit, and receives the vehicle speed vx acquired by the vehicle speed sensor 26 and the acceleration Gx acquired by the acceleration sensor 27, and outputs an estimated value θx of the road surface gradient on which the vehicle 10 is traveling. It is a functional element. The estimation unit 32 includes a differentiation block 32a, an addition block 32b, a division block 32c, and an inverse sine function block 32d. When it is considered that the road gradient is small, since sin θ≈θ, the inverse sine function block 32d may not be used.

  The output unit 33 functions as an output unit and receives the estimated value θx output from the estimating unit 32 and is estimated before estimating the estimated value θx or the estimated value θx as a road surface gradient for each sampling period. This is a functional element that outputs a pre-start estimated value θ (x−1), which is a calculated value, to the control unit 28 and the vehicle weight calculation unit 29.

The output unit 33 is a functional element that outputs the pre-start estimated value θ (x−1) until the vehicle 10 travels in a direction according to the driver's operation command at the time of start. Specifically, when a predetermined condition is satisfied, the output unit 33 receives the vehicle speed vx acquired by the vehicle speed sensor 26, starts the vehicle 10, and the vehicle speed vx changes from zero to a preset threshold value va. Until that time, the pre-start estimated value θ (x−1) is output. On the other hand, the output unit 33 outputs the estimated value θx when the condition is not satisfied.

  The threshold value va is set to a value that can specify that the vehicle 10 is starting in a direction according to an operation command from the driver's accelerator pedal 21 or shift lever 23. For example, the threshold value va is a value that can specify that when the vehicle 10 starts on an uphill road, the shift lever 23 is operated to the forward position and the vehicle 10 is surely moving forward in the direction of going up the uphill road. Can be illustrated. Further, as the threshold value va, when the vehicle 10 starts on a downhill road, a value that can specify that the shift lever 23 is operated to the reverse drive position and the vehicle 10 is surely going backward in the direction of going up the downhill road. Can be illustrated.

  In this embodiment, the output unit 33 is inputted with an estimated value θx, an estimated value θ (x−1) before starting, a vehicle speed vx, and a lever position Px, and a switch block 33a, an if block 33b, and a delay block 33c. have.

  The switch block 33a receives the estimated value θx, the estimated value θ (x−1) before starting, and the binary signal, and outputs the estimated value θx when the binary signal is “0”. When the value signal is “1”, an estimated value θ (x−1) before starting is output.

  The if block 33b receives the pre-start estimated value θ (x−1) and the lever position Px, and based on the condition, the switch block 33a has either a binary signal “0” or “1”. Output one. The if block 32b determines whether or not the vehicle 10 starts in the direction of climbing the hill as a condition.

  Next, the road surface gradient estimation method of the present invention will be described as each function of the road surface gradient calculation unit 31 with reference to the flowchart of FIG. The following road surface gradient estimation method is started when the control device 20 of the vehicle 10 is energized, and is repeatedly performed at regular intervals (sampling time) to estimate the road surface gradient in real time. Then, the control device 20 ends when a power failure occurs.

When starting, the vehicle speed sensor 26 acquires the vehicle speed vx, and the acceleration sensor 27 acquires the acceleration Gx (S110). Next, the road surface gradient calculation unit 31 estimates the estimated value θx of the road surface gradient on which the vehicle 10 is traveling by the function of the estimation unit 32 (S120). Specifically, the estimation unit 32 outputs a differential value vx ′ obtained by time-differentiating the vehicle speed vx input by the differentiation block 32a. Next, a value obtained by subtracting the differential value vx ′ from the acceleration Gx by the addition block 32 b is output as a gravitational acceleration component (Gx−vx ′) applied in the longitudinal direction of the vehicle 10. Next, a value obtained by dividing the gravitational acceleration component (Gx−vx ′) applied in the front-rear direction of the vehicle 10 by the gravitational acceleration g is output by the division block 32c. Next, the inverse sine function block 32d estimates the estimated value θx using the inverse sine function (sin ⁻¹ ) as the input value. When the road gradient is small, since sin θ≈θ, the inverse sine function need not be used.

  Next, the road surface gradient calculating unit 31 determines whether or not the condition is satisfied by the function of the output unit 33 (S130). In this step, the road surface gradient calculation unit 31 determines that the condition is satisfied when the driver's operation command is a command for starting the vehicle 10 in the direction of climbing the hill, and determines that the condition is not satisfied otherwise. Specifically, in the output unit 33, if the pre-start estimated value θ (x−1) is positive and the lever position Px is a position other than the parking position, the reverse position, and the neutral position, the driver 33 uses the if block 33b. Is determined to be a command for starting the vehicle 10 in the direction of climbing the uphill road. Further, when the pre-start estimated value θ (x−1) is negative and the lever position Px is the reverse drive position, it is determined that the driver's operation command is a command to start the vehicle 10 in the direction of going up the downhill road. When it is determined that the condition is satisfied, the process proceeds to determination by the check block 33d that is an action block. On the other hand, when it is determined that the condition is not satisfied, “0” is output as a binary signal to the switch block 33a by the input block 33e which is an action block.

  Next, the road surface gradient calculating unit 31 determines whether or not the vehicle speed vx is equal to or lower than the threshold value va by the function of the output unit 33 (S140). Specifically, when the check block 33d determines that the vehicle speed vx is equal to or less than the threshold value va, the output unit 33 outputs “1” as a binary signal to the switch block 33a. On the other hand, if it is determined that the vehicle speed vx exceeds the threshold value va, “0” is output to the switch block 33a as a binary signal.

  Next, when the condition is satisfied and the vehicle speed vx is determined to be equal to or less than the threshold value va, “1” is input as a binary signal and the switch block 33 a is switched. The estimated value θ (x−1) before starting is output by the function (S150). On the other hand, when it is determined that the condition is not satisfied or the vehicle speed vx exceeds the threshold value va, when “0” is input as the binary signal and the switch block 33 a is switched, the road surface gradient calculating unit 31 is connected to the output unit 33. The estimated value θx is output by the function (S160). Then, return to the start.

  When the above road surface gradient estimation method is performed when the vehicle 10 starts after stopping on a slope, the road surface gradient is output as an output value until the vehicle 10 travels in a direction according to a driver's operation command at the time of start. Hold at θx. That is, the road surface gradient is held at the pre-start estimated value θ (x−1) estimated before the vehicle 10 starts.

  In this way, the estimated value θ (x−1) before starting that is estimated before the vehicle 10 starts is output until the vehicle 10 starts and proceeds in the direction according to the driver's operation command when starting. Therefore, until the error of the estimated value θx of the road surface gradient decreases, a constant value can be held as the road surface gradient by the estimated value θ (x−1) before starting. This eliminates the effects of vibration at the start of the vehicle 10 and the effects of sliding on the slope, which is advantageous in reducing the estimation error of the road surface gradient at the start of the vehicle 10, and the road surface gradient with high accuracy. Can be estimated.

  On the other hand, since the estimated value θx estimated by the estimation unit 32 is sequentially output every sampling period after the vehicle 10 has traveled in the direction according to the driver's operation command at the time of starting, the road surface gradient after the vehicle 10 has started. This is advantageous in reducing the estimation error.

  Further, since the pre-start estimated value θ (x−1) is held until the vehicle proceeds in the direction according to the driver's operation command at the time of start, a low-pass filter that removes noise is used when estimating the road surface gradient. Compared to the prior art, the filter processing has no output delay, and the road surface gradient estimation response can be ensured. Thereby, it becomes advantageous for the estimation of the road surface gradient in real time, and the estimation accuracy of the road surface gradient when the vehicle 10 starts can be improved.

  In this embodiment, since the output unit 33 compares the vehicle speed vx with the threshold value va, the vehicle 10 is instructed by the driver until the vehicle starts and the vehicle speed vx changes from zero to the threshold value va. The estimated value θ (x−1) before starting can be held until it is certain that the vehicle has started in the direction corresponding to the.

  Since the vehicle speed sensor 26 acquires the vehicle speed vx with the rotation speed pulse as described above, the vehicle speed sensor 26 cannot acquire the direction. For example, when the vehicle 10 starts on an uphill road, even if the vehicle 10 slips down in the direction of descending the uphill road, the vehicle speed sensor 26 detects the vehicle speed that has fallen down. Therefore, the vehicle speed vx and the threshold value va are compared to determine the start direction of the vehicle 10 that cannot be acquired by the vehicle speed sensor 26. Thereby, when the vehicle 10 moves against the direction according to the driver's operation command, the road surface is obtained by using the estimated pre-start estimated value θ (x−1) before starting at that time. The gradient estimation error can be reduced.

  Therefore, it is preferable that the threshold value va is larger than the speed of falling down in the downhill direction that occurs when the vehicle is going to start in the uphill direction. Since the sliding speed of the vehicle 10 is proportional to the vehicle weight of the vehicle 10, the threshold value va may be increased as the vehicle weight increases.

  As described above, in this embodiment, the vehicle speed vx and the threshold value va are compared. However, the output unit 33 only needs to be able to determine whether or not the vehicle 10 has advanced in the direction according to the driver's operation command at the start. . For example, a device for acquiring the distance traveled by the vehicle 10 is provided, and based on the distance, it is determined whether or not the vehicle 10 has traveled a predetermined distance in a direction according to a driver's operation command at the time of starting. Also good. Moreover, the apparatus which acquires the time after the vehicle 10 started is provided, and based on the time, whether the vehicle 10 advanced in the direction according to the driver | operator's operation command at the time of starting more than predetermined time or not. You may judge.

  In this embodiment, since the output unit 33 determines the driver's operation command at the start based on the positive / negative of the estimated value θ (x−1) before start and the lever position Px, the vehicle 10 slips on the slope. The influence of the road surface gradient on the output value θx can be reliably eliminated. Thereby, the estimation accuracy of the road surface gradient can be improved.

  As described above, in this embodiment, the determination is made based on the sign of the pre-start estimated value θ (x−1) and the lever position Px. However, as the output unit 33, the driver's operation command at the start climbs the slope. What is necessary is just to be able to determine whether it is the instruction | command to start the said vehicle in the direction to do. For example, it may be determined by using a slope start assisting device that avoids slippage of the vehicle 10 on a slope and whether or not the device is activated.

  As illustrated in FIGS. 5 and 6, the road surface gradient calculation unit 31 of the road surface gradient estimation device 30 of the second embodiment is different from the first embodiment in the function of the output unit 33.

  The output unit 33 of the second embodiment has an if block 33f, and the pre-start estimated value θ (x−1) and the vehicle speed vx are input, and the vehicle speed vx is output to the estimation unit 32 or output. This is a functional element that outputs the estimated value θ (x−1) before starting to the unit 33. The if block 33f compares the vehicle speed vx with a preset threshold value va. When the vehicle speed vx exceeds the threshold value va, the if block 33f outputs the vehicle speed vx to the estimation unit 32, while the vehicle speed vx is zero from the threshold value. Until it becomes, the pre-start estimated value θ (x−1) is output. In other words, in this embodiment, the output unit 33 is a function that prohibits the estimation unit 32 from estimating the estimated value θx until the vehicle speed vx acquired by the vehicle speed sensor 26 reaches the threshold value va from zero. Is an element.

  In this embodiment, since it is prohibited to estimate the road surface gradient until it is certain that the vehicle 10 has started in the direction corresponding to the driver's operation command, the road surface gradient is determined by the estimated value θ (x−1) before starting. Can hold a constant value. This eliminates the effects of vibration when the vehicle 10 is started and the effects of slipping down on the slope, which is advantageous for reducing the estimation error when the vehicle 10 is started. Further, since the estimation of the road surface gradient is prohibited until it is certain that the vehicle 10 has started in the direction corresponding to the driver's operation command, the responsiveness of the estimation of the road surface gradient can be further ensured.

  In this embodiment, the road surface gradient calculating unit 31 does not have the if block 33b, but may have the if block 33b as in the first embodiment. In this case, when the condition is satisfied and the vehicle speed vx is determined to be equal to or less than the threshold value va, the estimation of the road surface gradient in the estimation unit 32 is prohibited, while the condition is not satisfied or the vehicle speed vx exceeds the threshold value va. When the determination is made, the estimation by the estimation unit 32 is permitted.

  In the above-described embodiment, the vehicle 10 has been described as an example of a large vehicle such as a truck. However, the road surface gradient estimation device 30 of the present invention can also be applied to buses, ordinary vehicles, and traction vehicles (tractors). The type is not limited.

  In the above-described embodiment, the example in which the road surface gradient estimation device 30 includes the road surface gradient calculation unit 31, the vehicle speed sensor 26, and the acceleration sensor 27 has been described, but the present invention is not limited to this. For example, the road surface gradient estimation device 30 may be composed of one sensor that functions as vehicle speed acquisition means, acceleration acquisition means, estimation means, and output means, and hardware that functions as holding means.

  In the above-described embodiment, the road surface gradient estimation device 30 has been described as an example of a configuration that does not include a filter unit that removes noise by filter processing, but the present invention is not limited to this. For example, you may have a filter part which filters and outputs with the low-pass filter which has a variable time constant with respect to the input value. The filter unit includes between the vehicle speed sensor 26 and the estimation unit 32, between the acceleration sensor 27 and the estimation unit 32, between the differentiation block 32a and the addition block 32b of the estimation unit 32, and between the estimation unit 32 and the output unit 33. It is good to arrange in either. In addition, the time constant of the low-pass filter of the filter unit may be varied based on a numerical value relating to the cause of the attitude change of the vehicle 10.

DESCRIPTION OF SYMBOLS 10 Vehicle 26 Vehicle speed sensor 27 Acceleration sensor 30 Road surface gradient estimation apparatus 31 Road surface gradient calculating part 32 Estimation part 33 Output part (theta) x Estimated value (theta) (x-1) Pre-start estimated value vx Vehicle speed Gx Acceleration

Claims (5)

Vehicle speed acquisition means for acquiring the vehicle speed of the vehicle;
Acceleration acquisition means for acquiring acceleration in the longitudinal direction of the vehicle;
An estimation means for inputting the vehicle speed acquired by the vehicle speed acquisition means and the acceleration acquired by the acceleration acquisition means and outputting an estimated value obtained by estimating a road surface gradient on which the vehicle is traveling based on the vehicle speed and acceleration; ,
The estimated value estimated by the estimating means before the vehicle starts until the estimated value estimated by the estimating means is input and the vehicle proceeds in the direction according to the operation command at the time of starting. Output means for outputting a road surface gradient as a road surface gradient. The vehicle speed acquired by the vehicle speed acquisition means is input to the output means,
The road surface gradient estimation device according to claim 1, wherein the time until the vehicle travels is a time until the vehicle starts and the vehicle speed reaches a preset threshold value from zero.   2. The configuration according to claim 1, wherein when the operation command is a command to start the vehicle in a direction of climbing a slope, the output means outputs the estimated value before starting as a road surface gradient until the vehicle travels. The road surface gradient estimation apparatus according to 2. The output means is input with the estimated value before starting and a lever position of a shift lever for operating a transmission mounted on the vehicle,
The road surface gradient estimation apparatus according to claim 3, wherein the output means determines whether the operation command is the command based on the pre-start estimated value and the lever position. In the road gradient estimation method for acquiring the vehicle speed and the acceleration in the longitudinal direction of the vehicle, and estimating the estimated value of the road gradient on which the vehicle is traveling based on the acquired vehicle speed and acceleration,
Determining whether the vehicle has traveled in the direction according to the operation command at the start,
A road surface gradient estimation method characterized in that a pre-start estimated value estimated before the vehicle starts is used as a road surface gradient until it is determined that the vehicle has advanced in a direction according to the operation command.

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