Vehicle speed estimation device

Abstract

To provide a vehicle body speed estimation device which can improve estimation accuracy of the vehicle body speed.SOLUTION: A vehicle body speed estimation device 7 estimates a vehicle body speed of a dump truck 1 in which pressure sensors 5a, 5b are arranged at least at two positions in a front-back direction of the vehicle. The vehicle body speed estimation device 7 comprises the steps of: estimating loads at the arrangement position of the pressure sensors 5a, 5b based on the front-back direction acceleration detected by an acceleration meter installed in the dump truck 1 and a first motion model simulating vertical motion of the vehicle; estimating road surface disturbance force generated by road surface inclination based on a difference between the estimated loads and the loads detected by the pressure sensor 5a, 5b; estimating a road surface inclination angle based on the estimated road surface disturbance force; and estimating the vehicle body speed based on the estimated road surface inclination angle.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] As a vehicle speed estimation device, for example, as described in Patent Document 1, a technique is known in which an observer is configured based on a vehicle motion model to estimate the longitudinal speed of a vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-67300 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the technology described in Patent Document 1, when the road surface has a gradient, a force in the fore-and-aft direction acts on the vehicle due to gravity, which causes errors in estimating the vehicle's fore-and-aft speed, reducing the estimation accuracy.

[0005] The present invention has been made to solve the above technical problems, and has an object to provide a vehicle speed estimation device that can improve the accuracy of estimating the vehicle speed. [Means for solving the problem]

[0006] The vehicle speed estimation device of the present invention is a vehicle speed estimation device that estimates a vehicle speed for a vehicle having load detection devices arranged at at least two locations in the forward / rearward direction of the vehicle, and is characterized in that the vehicle speed estimation device estimates a load at a location where the load detection devices are arranged using a forward / rearward acceleration detected by an accelerometer arranged on the vehicle and a first motion model that simulates the up and down movement of the vehicle, estimates a road disturbance force generated by a road surface inclination based on a difference between the estimated load and the load detected by the load detection device, estimates a road surface inclination angle based on the estimated road surface disturbance force, and estimates the vehicle speed based on the estimated road surface inclination angle.

[0007] In the vehicle speed estimation device of the present invention, first, the load at the location of the load detection device is estimated using the longitudinal acceleration detected by the accelerometer and a first motion model that simulates the up and down movement of the vehicle, then the road disturbance force generated by the road surface inclination is estimated based on the difference between the estimated load and the load detected by the load detection device, and the road surface inclination angle is estimated based on the estimated road surface disturbance force. Then, the vehicle speed is estimated based on the estimated road surface inclination angle, thereby improving the estimation accuracy of the vehicle speed. Effect of the Invention

[0008] According to the present invention, the accuracy of estimating the vehicle speed can be improved. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a side view showing the dump truck. [Diagram 2] 1 is a schematic configuration diagram showing a vehicle speed estimation device according to an embodiment; [Diagram 3] FIG. 2 is a schematic diagram showing a tire-road surface acting force estimating unit. [Figure 4] FIG. 2 is a schematic diagram showing a road surface gradient estimation unit; [Diagram 5] FIG. 2 is a schematic configuration diagram showing a vehicle pitch angular acceleration estimating unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of a vehicle body speed estimation device according to the present invention will be described with reference to the drawings. In the description of the drawings, the same elements are given the same reference numerals, and duplicated description thereof will be omitted. In the following description, the up / down, left / right, front / rear directions and positions are based on a vehicle (here, a dump truck) on which the vehicle body speed estimation device is mounted. Note that the vehicle on which the vehicle body speed estimation device is mounted is not limited to a dump truck.

[0011] FIG. 1 is a side view showing a dump truck. As shown in FIG. 1, the dump truck 1 includes a vehicle body 2, a pair of left and right front wheels 3a attached to the front side of the vehicle body 2, a pair of left and right rear wheels 3b attached to the rear side of the vehicle body 2, and a loading platform 6 supported on the vehicle body 2 so as to be capable of being raised and lowered. The rear wheels 3b are, for example, drive wheels, and are driven by an electric motor attached to the rear wheels 3b. The electric motor is inverter-controlled, and rotates by receiving electric energy generated by, for example, a diesel engine built into the vehicle body 2. The drive wheels are not limited to the rear wheels 3b, and may be the front wheels 3a.

[0012] The vehicle body 2 is supported by a pair of left and right suspension cylinders 4a attached to the front side of the vehicle body 2, and a pair of left and right suspension cylinders 4b attached to the rear side of the vehicle body 2. Pressure sensors (load detection devices) 5a, 5b are attached to each of the suspension cylinders 4a, 4b. The pressure sensors 5a, 5b detect the hydraulic pressure of a shock absorber of a suspension strut arranged on a wheel, for example. In addition, various sensors are attached to the vehicle body 2, including a torque sensor that detects the output of an electric motor, an acceleration sensor (accelerometer) that detects the acceleration in the front-rear direction of the vehicle (hereinafter referred to as "vehicle front-rear acceleration"), and an encoder that detects the wheel rotation speed.

[0013] The dump truck 1 is equipped with a vehicle speed estimation device 7 having a road surface gradient estimation unit 10. The vehicle speed estimation device 7 is arranged, for example, inside the vehicle body 2, and is used to estimate the vehicle speed including the speed in the longitudinal direction of the vehicle (hereinafter referred to as the "vehicle longitudinal speed"). In this embodiment, the estimation of the vehicle longitudinal speed by the vehicle speed estimation device 7 will be described. The vehicle speed estimation device 7 is configured by a microcomputer that combines, for example, a CPU (Central Processing Unit) that executes calculations, a ROM (Read Only Memory) as a secondary storage device that records programs for the calculations, and a RAM (Random Access Memory) as a temporary storage device that stores the calculation progress and temporary control variables. The vehicle speed estimation device 7 may be incorporated as a function into a vehicle control device mounted on the dump truck 1.

[0014] The vehicle speed estimation device 7 will be described in detail below with reference to FIGS.

[0015] Fig. 2 is a schematic diagram showing a vehicle speed estimation device according to an embodiment. As shown in Fig. 2, when a dump truck 1 travels on a road surface, in addition to the motor torque output from the electric motor, forces such as gravity, a road disturbance force generated by a road surface inclination, and an action force that the tires receive from the road surface (hereinafter referred to as "tire-road surface action force") act on the dump truck 1. For this reason, when estimating the vehicle longitudinal speed, the influence of these forces must be taken into consideration, and it is necessary to obtain the motor torque, the load, the vehicle longitudinal acceleration, and the wheel rotation speed.

[0016] The motor torque is detected, for example, by a torque sensor attached to the rear wheel 3b. The load is detected by the above-mentioned pressure sensors 5a, 5b. The vehicle body longitudinal acceleration is detected, for example, by an acceleration sensor attached to the vehicle body 2. The wheel rotation speed is detected, for example, by an encoder attached to the rear wheel 3b. Note that here, instead of using a torque sensor, the current value of the electric motor may be measured, and the motor torque may be calculated based on the measured current value.

[0017] 2, the vehicle speed estimation device 7 of this embodiment mainly includes a tire-road surface acting force estimating section 30, a road surface gradient estimating section 10, and a vehicle body speed estimating section 20. Each of these will be described in turn below.

[0018] [About the tire-road force estimator] Fig. 3 is a schematic diagram showing a tire-road surface acting force estimating unit. The tire-road surface acting force estimating unit 30 estimates a tire-road surface acting force based on a motor torque and a wheel rotation speed, and outputs the estimation result (i.e., an estimated tire-road surface acting force). As shown in Fig. 3, the tire-road surface acting force estimating unit 30 has two filters 31a and 31b, a wheel motion model 32, and a differentiator 33. The filters 31a and 31b are, for example, filters having the same frequency characteristics. If it is desired to remove high-frequency noise, low-pass filters may be used for these filters 31a and 31b.

[0019] The equation of motion of a wheel can be expressed as follows:

[0020]

number

[0021] TIFF0007627618000002.tif12169

[0022] TIFF0007627618000003.tif31170

[0023]

number

[0024] TIFF0007627618000005.tif28170

[0025] TIFF0007627618000006.tif16170

[0026] TIFF0007627618000007.tif22170

[0027] 4 is a schematic diagram showing the configuration of a road surface gradient estimator according to an embodiment. As shown in FIG 4, the road surface gradient estimator 10 includes a road surface disturbance estimator 11, a road surface inclination angle estimator 12, and a vehicle pitch angular acceleration estimator 13.

[0028] The equation of motion of the dump truck 1 in the vertical direction can be expressed by, for example, the following equation (3).

[0029]

number

[0030] TIFF0007627618000009.tif33170

[0031] The road surface disturbance estimation unit 11 is, for example, a calculation model (first motion model) that simulates the up and down motion of the dump truck 1. The equation of motion of this calculation model can be expressed by the following formula (4).

[0032]

number

[0033] TIFF0007627618000011.tif32167

[0034] TIFF0007627618000012.tif26167

[0035] TIFF0007627618000013.tif26168

[0036] TIFF0007627618000014.tif32170

[0037] TIFF0007627618000015.tif26167

[0038]

number

[0039] TIFF0007627618000017.tif22168

[0040] In order to improve the estimation accuracy of the vehicle pitch angular acceleration, the vehicle pitch angular acceleration estimator 13 of this embodiment further estimates the vehicle pitch angular acceleration by utilizing the loads detected by the pressure sensors 5a and 5b.

[0041] TIFF0007627618000018.tif48169

[0042] The gain 15 can be calculated using, for example, a design algorithm of a Kalman filter. The vehicle pitch angular acceleration estimator 13 outputs the estimation result (i.e., estimated vehicle pitch angular acceleration) to the vehicle body speed estimator 20.

[0043] As described above, the vehicle body 2 of the dump truck 1 is supported by a pair of left and right suspension cylinders 4a attached to the front side of the vehicle body 2 and a pair of left and right suspension cylinders 4b attached to the rear side of the vehicle body 2, and pressure sensors 5a and 5b are attached to the suspension cylinders 4a and 4b, respectively. Based on the detection results of these pressure sensors 5a and 5b, the masses of the vehicle body 2, the loading platform 6, and the cargo loaded on the loading platform 6 can be obtained.

[0044] TIFF0007627618000019.tif37170

[0045] TIFF0007627618000020.tif27168

[0046] Here, the reason why the road surface inclination angle and the vehicle pitch angular acceleration are required in estimating the vehicle body longitudinal speed will be explained. First, the reason why the road surface inclination angle is required will be explained.

[0047] The equation of motion of the dump truck 1 in the front-rear direction can be expressed by, for example, the following equation (6).

[0048]

number

[0049] TIFF0007627618000022.tif37170

[0050] Next, the reason why the vehicle pitch angular acceleration is required will be explained.

[0051] TIFF0007627618000023.tif27170

[0052]

number

[0053] TIFF0007627618000025.tif26168

[0054] TIFF0007627618000026.tif22168

[0055] Furthermore, the vehicle speed estimating unit 20 of this embodiment improves the accuracy of estimating the vehicle longitudinal speed by utilizing the vehicle longitudinal acceleration detected by the acceleration sensor.

[0056] TIFF0007627618000027.tif36170

[0057] TIFF0007627618000028.tif58167

[0058] Furthermore, according to the vehicle speed estimation device 7 equipped with such a road surface gradient estimation unit 10, when the vehicle longitudinal speed is estimated using the road surface inclination angle and the vehicle pitch angular acceleration, which have high estimation accuracy, it is possible to estimate the vehicle longitudinal speed with high accuracy.

[0059] In this embodiment, the load detection device is described by taking the pressure sensors 5a and 5b that detect the hydraulic pressure of the shock absorbers of the suspension struts arranged on the wheels as an example, but the load detection device may be an accelerometer. When an accelerometer is used, the road surface inclination angle and the vehicle pitch angular acceleration can be estimated in the same manner as described above based on the results detected by the accelerometer.

[0060] In this embodiment, the load detection devices must be disposed at least in two locations in the front-rear direction of the vehicle. This is because when the dump truck 1 travels on an inclined road surface (e.g., downhill or uphill), the load applied to the front wheels is different from the load applied to the rear wheels, and therefore, by disposing the load detection devices on the front and rear sides of the vehicle, the load can be obtained more accurately.

[0061] Also, in the above embodiment, an example has been described in which the vehicle speed estimation device 7 is mounted on the dump truck 1, but the vehicle speed estimation device 7 may be provided independently of the dump truck 1. For example, the vehicle speed estimation device 7 is disposed in a server communicably connected to the dump truck 1, acquires the detection results of the sensors of the dump truck 1 via wireless communication or the like, performs the above-mentioned estimations, and transmits the estimation results to the dump truck 1.

[0062] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various design modifications can be made without departing from the spirit of the present invention as described in the claims. [Explanation of symbols]

[0063] 1. Dump truck 2. Body 3a front wheel 3b rear wheel 4a, 4b Suspension cylinder 5a, 5b Pressure sensor (load detection device) 6 Cargo Platform 7 Vehicle speed estimation device 10 Road surface gradient estimation unit 11 Road disturbance estimation unit 12 Road slope angle estimation section 13 Vehicle pitch angular acceleration estimation unit 14 Vehicle vertical movement model 15 Gain 20 Vehicle speed estimation unit 30 Tire-road surface acting force estimation unit 31a, 31b Filter 32 Wheel Motion Model 33 Differentiator

Claims

1. A vehicle speed estimation device that estimates a vehicle speed for a vehicle having load detection devices disposed at at least two locations in a front-rear direction of the vehicle, comprising: The vehicle speed estimation device includes: a load at a position where the load detection device is disposed, is estimated using a forward / rearward acceleration detected by an accelerometer disposed on the vehicle and a first motion model that simulates an up / down motion of the vehicle, and a road disturbance force generated by a road surface inclination is estimated based on a difference between the estimated load and the load detected by the load detection device; A road surface inclination angle is estimated based on the estimated road surface disturbance force; A vehicle speed estimation device which estimates a vehicle speed based on an estimated road surface inclination angle.

2. 2. The vehicle body speed estimation device according to claim 1, wherein the vehicle body speed estimation device estimates a vehicle pitch angular acceleration using the estimated road surface inclination angle, the load detected by the load detection device, the longitudinal acceleration detected by the accelerometer, and a second motion model that simulates up-down motion of the vehicle.

3. 3. The vehicle speed estimating device according to claim 2, wherein the vehicle speed estimating device estimates the vehicle longitudinal speed based on the estimated road surface inclination angle and vehicle pitch angular acceleration.

4. 4. The vehicle speed estimation device according to claim 2 or 3, wherein the first motion model is a motion model that does not take into account a road disturbance force generated by a road surface inclination, and the second motion model is a motion model that takes into account a road disturbance force generated by a road surface inclination.

5. The vehicle body speed estimation device according to any one of claims 2 to 4, wherein the vehicle body speed estimation device estimates a load at a position where the load detection device is arranged using an estimated road surface inclination angle, a longitudinal acceleration detected by the accelerometer, and the second motion model, and estimates the vehicle pitch angular acceleration based on a difference between the estimated load and the load detected by the load detection device.

6. 6. The vehicle speed estimating device according to claim 1, wherein the load detecting device is a pressure sensor that detects hydraulic pressure of a shock absorber attached to a wheel of the vehicle.

7. The vehicle speed estimating device according to any one of claims 1 to 5, wherein the load detecting device is an accelerometer.

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