Load capacity estimation system for special-purpose vehicles, load capacity estimation method for special-purpose vehicles, and computer program

Abstract

To provide a system and a method for estimating the weight of the load in a specially-equipped vehicle and a computer program.SOLUTION: A specially-equipped vehicle having a hydraulic actuator for lifting a cargo box includes: a first acquisition unit for acquiring first data on the magnitude of a hydraulic pressure from a pressure meter for measuring the magnitude of a hydraulic pressure that acts on the hydraulic actuator; a second acquisition unit for acquiring second data on the magnitude of an inclination angle from an inclination meter for measuring an inclination angle of the specially-equipped vehicle; a storage unit for storing more than one relation between the inclination angle and the magnitude of the hydraulic pressure when the weight and the position of a loaded material are changed, in relation to the weight of the loaded material; and an estimation unit for estimating the weight of the load in the cargo box with reference to the relation stored in the storage unit when the first data and the second data are acquired.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] This invention relates to a system for estimating the load capacity of a special-purpose vehicle, a method for estimating the load capacity of a special-purpose vehicle, and a computer program. [Background technology]

[0002] In recent years, large vehicles such as trucks have been equipped with scales to measure their own weight (load capacity).

[0003] Conventional vehicle scales use load sensors attached to both ends of the front and rear axles to measure the load on each tire (front, rear, left, and right), and calculate the load weight from the sum of the outputs of each load sensor. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2004-132871 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, conventional weighing scales use a method that converts the sum of the outputs from each load sensor into the load weight. Therefore, they may not be able to measure the correct load weight when the vehicle is on an incline or when the load on the cargo bed is not evenly balanced.

[0006] The present invention aims to provide a load weight estimation system for special-purpose vehicles, a load weight estimation method for special-purpose vehicles, and a computer program that can accurately estimate the load weight even when the balance of the load on the cargo bed is not uniform. [Means for solving the problem]

[0007] A load weight estimation system for a special-purpose vehicle according to one aspect of the present invention relates to a special-purpose vehicle equipped with a hydraulic actuator for raising and lowering a cargo box, and comprises: a first acquisition unit that acquires first data relating to the magnitude of the hydraulic pressure from a pressure gauge that measures the magnitude of the hydraulic pressure acting on the hydraulic actuator; a second acquisition unit that acquires second data relating to the inclination angle from an inclinometer that measures the inclination angle of the special-purpose vehicle; a storage unit that stores multiple relationships between the inclination angle and the magnitude of the hydraulic pressure when the weight and loading position of the cargo are changed, in relation to the weight of the cargo; and an estimation unit that, when the first data and the second data are acquired, estimates the load weight in the cargo box by referring to the relationships stored in the storage unit.

[0008] A method for estimating the load weight of a special-purpose vehicle according to one aspect of the present invention relates to a special-purpose vehicle equipped with a hydraulic actuator for raising and lowering a cargo box. The method involves obtaining first data relating to the magnitude of the hydraulic pressure acting on the hydraulic actuator from a pressure gauge that measures the magnitude of the hydraulic pressure, and obtaining second data relating to the inclination angle from an inclinometer that measures the inclination angle of the special-purpose vehicle. When the first and second data have been obtained, a computer performs a process to estimate the load weight in the cargo box by referring to a storage unit that stores multiple relationships between the inclination angle and the magnitude of the hydraulic pressure when the weight and position of the cargo are changed, in relation to the weight of the cargo.

[0009] A computer program according to one aspect of the present invention is a computer program that causes a computer to perform a process to estimate the load weight in the cargo box by referring to a storage unit that stores multiple data relating to the relationship between the angle of inclination and the magnitude of the hydraulic pressure when the weight and position of the load are changed, in relation to the weight of the load, with respect to a special-purpose vehicle equipped with a hydraulic actuator for raising and lowering a cargo box. The computer program obtains first data relating to the magnitude of the hydraulic pressure from a pressure gauge that measures the magnitude of the hydraulic pressure acting on the hydraulic actuator, and second data relating to the angle of inclination from an inclinometer that measures the angle of inclination of the special-purpose vehicle. When the first data and the second data are obtained, the computer program causes a computer to perform a process to estimate the load weight in the cargo box by referring to a storage unit that stores multiple data relating to the weight of the load and the angle of inclination and the magnitude of the hydraulic pressure when the weight and position of the load are changed. [Effects of the Invention]

[0010] According to the present application, even when the balance of the loads on the loading platform is not uniform, the loading weight can be accurately estimated.

Brief Description of the Drawings

[0011] [Figure 1] It is a side view showing the overall configuration of the special vehicle according to Embodiment 1. [Figure 2] It is a plan view showing the overall configuration of the special vehicle according to Embodiment 1. [Figure 3] It is a side view of the load box in the upright state. [Figure 4] It is a block diagram for explaining the configuration of the loading weight estimation system. [Figure 5] It is a graph showing the relationship between the center of gravity position of the load box including the load and the change in the pitch angle. [Figure 6] It is a graph showing the relationship between the hydraulic pressure value and the pitch angle when the loading weight and the loading position are changed. [Figure 7] It is a conceptual diagram showing an example of the relationship table. [Figure 8] It is an explanatory diagram for explaining the method of estimating the loading weight in Embodiment 1. [Figure 9] It is a flowchart for explaining the procedure of estimating the loading weight in Embodiment 1. [Figure 10] It is a schematic diagram showing an example of the display of the loading weight. [Figure 11] It is an explanatory diagram for explaining the method of estimating the loading weight in Embodiment 2. [Figure 12] It is a block diagram for explaining the configuration of the loading weight estimation system in Embodiment 3. [Figure 13] It is a flowchart for explaining the procedure of estimating the loading weight in Embodiment 3. [Figure 14] It is a block diagram for explaining the configuration of the loading weight estimation system in Embodiment 4. [Figure 15] It is a flowchart for explaining the procedure of estimating the loading weight in Embodiment 4. [Figure 16] This is a block diagram illustrating the configuration of the load weight estimation system in Embodiment 5. [Figure 17] This is a flowchart illustrating the procedure for estimating the load weight in Embodiment 5. [Figure 18] This is a schematic diagram illustrating an example of a learning model configuration. [Modes for carrying out the invention]

[0012] The present invention will be described in detail below with reference to the drawings illustrating its embodiments. (Embodiment 1) Figure 1 is a side view showing the overall configuration of the special-purpose vehicle 1 according to Embodiment 1, Figure 2 is a top view thereof, and Figure 3 is a side view with the cargo box in an upright position. The special-purpose vehicle 1 illustrated in Figures 1 to 3 is a dump truck equipped with a truck chassis 2 which is the driving unit and a dumping device 3 which is an example of a bodywork device mounted on the driving unit. In the following description, the front, rear, left, right, and up and down directions refer to the front, rear, left, right, and up and down directions as seen from the driver's seat of the truck chassis 2. Note that in Figure 2, the dumping device 3 is removed for illustrative purposes.

[0013] The truck chassis 2 comprises a cab 20 in which a driver's seat is provided, and a chassis frame 21 that supports the cab 20. The chassis frame 21 is composed of a pair of left and right main frames (longitudinal joists) 21A, 21A extending in the longitudinal direction, and a plurality of cross members (transverse joists) 21B, ..., 21B connecting the pair of left and right main frames 21A, 21A (see Figure 2). The front wheels 22F and rear wheels 22R, 22R of the truck chassis 2 are rotatably mounted to the main frames 21A, 21A via a suspension system not shown. The truck chassis 2 comprises an engine 70 (prime mover) and a transmission connected to the engine 70 via a clutch, and is configured to run by transmitting the driving force of the engine 70 to the drive system of the drive wheels (e.g., the front wheels 22F) via the transmission.

[0014] The dumping device 3 comprises a subframe 30 fixed to the chassis frame 21, and a cargo box 4 supported by the subframe 30, on which cargo such as soil and sand is loaded. The cargo box 4 is rotatably supported around a hinge shaft 31 extending in the left-right direction at the rear end of the subframe 30. The cargo box 4 is an open-topped box and comprises a front panel 41, a pair of left and right side panels 42, and a rear panel (rear tailgate) 43 arranged to surround a rectangular bottom 40. The rear panel 43 is configured to be openable and closable.

[0015] The dumping device 3 is equipped with a hoist mechanism 5 for tilting the cargo box 4. The hoist mechanism 5 includes, for example, a lift arm 51, a hydraulic cylinder 52, and a tension link 53. When the hydraulic cylinder 52 of the hoist mechanism 5 is extended, the front of the cargo box 4 is lifted and rotates in a direction that increases the tilt angle. In this embodiment, the rotation of the cargo box 4 in a direction that increases the tilt angle is also called the raising of the cargo box 4. On the other hand, when the hydraulic cylinder 52 of the hoist mechanism 5 is shortened, the front of the cargo box 4 is lowered and rotates in a direction that decreases the tilt angle. In this embodiment, the rotation of the cargo box 4 in a direction that decreases the tilt angle is also called the lowering of the cargo box 4.

[0016] The hydraulic mechanism for extending and retracting the hydraulic cylinder 52 includes a hydraulic pump 61, a hydraulic oil tank 62, a control valve 63, and the like. The hydraulic pump 61, which is the hydraulic power source, is driven by the power of the engine 70 transmitted via a PTO 71 (Power Take-Off), which pumps hydraulic oil from the hydraulic oil tank 62 through the hydraulic piping 64 and supplies hydraulic oil (pressurized oil) to the hydraulic cylinder 52 through the main pipe 65 connected to the discharge port. The connection and disconnection of the power transmission from the engine 70 is switched by a PTO switch 72 located inside the cab 20.

[0017] The direction of supply of hydraulic fluid discharged from the hydraulic pump 61 is switched by a control valve 63 operated by a manual operating lever 67. For example, when the control valve 63 is in the neutral position by operating the operating lever 67, no hydraulic fluid is supplied from the hydraulic pump 61 to the hydraulic cylinder 52, and the cargo box 4 does not tilt. When the operating lever 67 is operated to the raised position, the control valve 63 is switched, and hydraulic fluid (pressurized oil) is supplied from the hydraulic pump 61 to the hydraulic cylinder 52. The hydraulic cylinder 52 extends as hydraulic fluid is supplied, raising the cargo box 4. On the other hand, when the operating lever 67 is operated to the lowered position, the control valve 63 is switched, and the hydraulic fluid supplied to the hydraulic cylinder 52 is returned to the hydraulic fluid tank 62. Consequently, the hydraulic cylinder 52 shortens, lowering the cargo box 4.

[0018] The hydraulic mechanism is equipped with a pressure gauge 81 for measuring the magnitude of the hydraulic pressure acting on the hydraulic cylinder 52. The special vehicle 1 is also equipped with an inclinometer 82 for measuring the inclination (pitch and roll) of the truck chassis 2 and an inclinometer 83 for measuring the inclination (pitch and roll) of the cargo box 4.

[0019] The pressure gauge 81 measures the cylinder pressure (hydraulic pressure) of the hydraulic cylinder 52 over time and outputs measurement data related to the measured cylinder pressure. The inclinometer 82 is attached to an appropriate location on the chassis frame 21 (for example, near the center in the front-rear and left-right directions). The inclinometer 82 measures the front-rear inclination (pitch) and left-right inclination (roll) of the truck chassis 2 over time, with respect to the direction of gravity (vertical direction), and outputs measurement data related to the measured inclination. The data on the inclination angle of the truck chassis 2 obtained from the inclinometer 82 can be considered as data on the inclination angle of the entire vehicle, i.e., the special-purpose vehicle 1. The inclinometer 83 is attached to an appropriate location on the cargo box 4 and measures the front-rear inclination (pitch) and left-right inclination (roll) of the cargo box 4 over time, with respect to the direction of gravity (vertical direction), and outputs measurement data related to the measured inclination. By taking the difference between the measurement value of the inclinometer 83 and the measurement value of the inclinometer 82, the dump angle of the cargo box 4 relative to the truck chassis 2 is calculated.

[0020] The special-purpose vehicle 1 is equipped with an estimation device 100 that estimates the weight of the cargo (loaded weight) based on data obtained from a pressure gauge 81 and an inclinometer 82. In this embodiment, the loaded weight represents the weight of the cargo loaded in the cargo box 4, and does not include the weight of the occupants riding in the special-purpose vehicle 1, the fuel loaded in the special-purpose vehicle 1, or the weight of the running gear and bodywork that constitute the special-purpose vehicle 1. The weight of the running gear and bodywork when the vehicle is not loaded is assumed to be known. The internal configuration of the estimation device 100 and the content of the processing performed by the estimation device 100 will be described in detail later, but in this embodiment, the loaded weight of the special-purpose vehicle 1 is estimated by utilizing the relationship between data including data on the magnitude of hydraulic pressure obtained from the pressure gauge 81 (first data), data on the inclinometer angle obtained from the inclinometer 82 (second data), and the loaded weight. The estimation device 100 is installed, for example, inside the cab 20. Alternatively, the estimation device 100 may be attached to the chassis frame 21.

[0021] In this embodiment, a dump truck equipped with a dumping device 3 is described as an example of a special-purpose vehicle 1. However, the special-purpose vehicle 1 is not limited to a dump truck, but may be any special-purpose vehicle equipped with a dumping device having a hydraulic cylinder, such as a dump-discharge type suction vehicle or a dump-discharge type refuse collection vehicle.

[0022] The configuration of the load weight estimation system according to this embodiment will be described below. Figure 4 is a block diagram illustrating the configuration of the load weight estimation system. The load weight display system includes an estimation device 100 that estimates the load weight of the special vehicle 1 based on data on the magnitude of hydraulic pressure obtained from a pressure gauge 81 and data on the inclination angle obtained from an inclinometer 82, and a display device 120 for notifying information regarding the load weight estimated by the estimation device 100.

[0023] The estimation device 100 is a dedicated or general-purpose computer and comprises a control unit 101, a storage unit 102, an operation unit 103, an input unit 104, an output unit 105, and a communication unit 106.

[0024] The control unit 101 includes, for example, a CPU (Central Processing Unit), ROM (Read Only Memory), and RAM (Random Access Memory). The ROM in the control unit 101 stores control programs that control the operation of each hardware component of the estimation device 100. The CPU in the control unit 101 executes the control programs stored in the ROM and various computer programs stored in the memory unit 102 (described later), thereby controlling the operation of each hardware component and realizing the function of the estimation device 100 in this embodiment. The RAM in the control unit 101 temporarily stores data used during the execution of calculations.

[0025] The control unit 101 may also be equipped with functions such as a clock for outputting date and time information, a timer for measuring the elapsed time from the time a measurement start instruction is given until a measurement end instruction is given, and a counter for counting numbers.

[0026] The storage unit 102 is equipped with a storage device such as a hard disk or flash memory. The storage unit 102 stores computer programs executed by the control unit 101, various data acquired from external sources, and various data generated inside the estimation device 100.

[0027] The computer programs stored in the memory unit 102 include an estimation program PG1 for estimating the load weight of the special-purpose vehicle 1 by referring to the relationships between data including first data, second data, and load weight.

[0028] The computer programs stored in the storage unit 102 are provided, for example, by a non-temporary recording medium RM1 on which the computer programs are recorded in a readable format. The recording medium RM1 is, for example, a portable memory such as a CD-ROM, USB memory, or SD (Secure Digital) card. The control unit 101 reads various programs from the recording medium RM1 using a reading device (not shown in the figure) and stores the read programs in the storage unit 102. Alternatively, the computer programs stored in the storage unit 102 may be provided via communication. In this case, the control unit 101 downloads the necessary computer programs from a predetermined server and stores the downloaded computer programs in the storage unit 102.

[0029] Furthermore, the memory unit 102 includes a relational table TB1 that stores the relationship between the tilt angle of the special vehicle 1 and the magnitude of the hydraulic pressure when the weight and position of the load are changed, in relation to the weight of the load. The configuration of the relational table TB1 will be described in detail later.

[0030] The operation unit 103 is composed of switches, buttons, etc., and accepts various operations. The control unit 101 performs appropriate processing based on the operations received through the operation unit 103. In this embodiment, the estimation device 100 is configured to include an operation unit 103, but the operation unit 103 is not essential, and operations may be accepted via externally connected equipment or a communication unit 106.

[0031] The input unit 104 is equipped with an interface for connecting various sensors, and sensors such as a pressure gauge 81 and inclinometers 82 and 83 are connected to it. These sensors may be connected to the input unit 104 by wire or by wireless connection. Measurement data related to the cylinder pressure of the hydraulic cylinder 52 output from the pressure gauge 81, measurement data related to the inclination of the special vehicle 1 output from the inclinometer 82, measurement data related to the inclination of the cargo box 4 output from the inclinometer 83, etc. are input to the input unit 104 as appropriate.

[0032] The output unit 105 is equipped with an output interface for connecting a display device 120, such as an LCD monitor. The display device 120 is installed, for example, near the driver's seat of the cab 20. Alternatively, the display device 120 may be installed on the rear side of the front panel 41. The output interface provided by the output unit 105 may be an output interface that outputs analog video signals, or it may be an output interface that outputs digital video signals such as DVI (Digital Visual Interface) or HDMI (High-Definition Multimedia Interface, registered trademark). For example, the output unit 105 outputs display data to the display device 120 in order to display the estimated load weight result on the display device 120.

[0033] In this embodiment, the display device 120 is connected to the outside of the estimation device 100, but the estimation device 100 may also be equipped with the display device 120.

[0034] The communication unit 106 is equipped with a communication interface for sending and receiving various types of data with external devices. An example of a party with which the estimation device 100 communicates via the communication unit 106 is various ECUs (Electronic Controller Units) and PLCs (Programmable Logic Controllers) mounted on the special-purpose vehicle 1. In this case, the communication unit 106 may be equipped with a communication port compliant with RS-485, for example, or a communication interface compliant with a communication standard for in-vehicle communication such as CAN (Controller Area Network), in order to communicate with the various ECUs and PLCs mounted on the special-purpose vehicle 1. Other examples of parties with which the estimation device 100 communicates via the communication unit 106 are server devices installed outside the special-purpose vehicle 1 or mobile terminals carried by the user. In this case, the communication unit 106 may be equipped with a communication interface compliant with wireless communication standards such as WiFi (registered trademark), 3G, 4G, 5G, or LTE (Long Term Evolution) in order to communicate with external server devices, etc.

[0035] The inventors of this invention have thoroughly investigated the influence of the weight and position of the cargo loaded in the cargo box 4 on the hydraulic pressure (cylinder pressure of the hydraulic cylinder 52) and the tilt angle of the special-purpose vehicle 1. Considering the characteristics of the special-purpose vehicle 1, the vehicle (dump truck) can be considered to be supported by "springs" in the form of the front wheels 22F, rear wheels 22R, and leaf suspension (not shown in the figure). Therefore, when cargo is loaded in the cargo box 4, the "springs" deflect due to the weight of the cargo, causing the vehicle to tilt. In other words, it is expected that there is some relationship between the weight of the cargo, the loading position, and the tilt of the vehicle.

[0036] Figure 5 is a graph showing the relationship between the center of gravity of the cargo box 4 including the load and the change in pitch angle. In this embodiment, by loading cargo of known weight into the cargo box 4, a state of even loading and a state of maximum possible uneven loading are created, and the center of gravity of the cargo box 4 including the load and the change in pitch angle of the truck chassis 2 are determined and plotted on the graph in each state. Here, the center of gravity of the cargo box 4 including the load is calculated, for example, using CAD (Computer-Assisted Design) data. The change in pitch angle represents the difference between the pitch angle of the truck chassis 2 before loading the load and the pitch angle of the truck chassis 2 after loading, and can be calculated based on data obtained from the inclinometer 82. Alternatively, the change in pitch angle may be calculated by CAE (Computer-Aided Engineering) analysis.

[0037] The change in pitch angle is expressed using the evenly loaded state, where the cargo is evenly distributed in the front-to-rear direction of the cargo box 4, as the baseline. That is, in the evenly loaded state, the change in pitch angle is considered to be zero. In this case, the pitch angle changes significantly to the negative side, for example, in the maximum unevenly loaded state, where the cargo is biased towards the front of the cargo box 4, and changes significantly to the positive side, for example, in the maximum unevenly loaded state, where the cargo is biased towards the rear of the cargo box 4. As shown in the graph in Figure 5, it can be seen that there is a roughly proportional relationship between the tilt of the truck chassis 2 and the center of gravity of the cargo box 4 including the cargo.

[0038] Figure 6 is a graph showing the relationship between hydraulic pressure and pitch angle when the load weight and loading position are changed. The horizontal axis of the graph represents the pitch angle of the truck chassis 2 obtained from the inclinometer 82, and the vertical axis represents the magnitude of the hydraulic pressure (cylinder pressure of the hydraulic cylinder 52) obtained from the pressure gauge 81. In this embodiment, by loading loads of known weight into the cargo box 4, a state of even loading and a state of maximum uneven loading at that weight were created, and the pitch angle of the truck chassis 2 and the magnitude of the hydraulic pressure were measured and plotted on the graph in each state.

[0039] Specifically, a 10-ton load was placed sequentially at the front and rear even loading positions, the front end, and the rear end of the cargo box 4. The pitch angle and hydraulic pressure were measured at each position, and the corresponding measurement points were plotted on a graph. As a result, three measurement points, indicated by black circles in the graph of Figure 6, were obtained. The state in which the load is placed at the front and rear end positions of the cargo box 4 corresponds to maximum uneven loading.

[0040] Similarly, the pitch angle and hydraulic pressure were measured for each case where a 9-ton load was loaded at each position, an 8-ton load was loaded at each position, ..., and a 1-ton load was loaded at each position, and the corresponding measurement points were plotted on a graph. As a result, three measurement points were obtained for each load weight. Note that for loads of 5 tons, 3 tons, 2 tons, and 1 ton, only measurement points were obtained when the load was placed at the front and rear evenly distributed positions of the cargo box 4. However, as with the other load weights, measurement points may also be obtained when the load was placed at the front and rear positions.

[0041] The dashed line shown in the graph of Figure 6 represents an approximate straight line that approximates the three measurement points for each predetermined load weight. If the horizontal axis of the graph is the x-axis, the vertical axis is the y-axis, and the load weight is W tons, then the approximate straight line is a w x+b w y+c w It is expressed as =0. Here, x is the pitch angle of the truck chassis 2, y is the hydraulic pressure value, a w ,b w ,c wis a coefficient. When measurement results (in the example of FIG. 6, there are three measurement points) for a loaded weight of W tons are obtained, approximate straight lines can be derived by determining coefficients a w , b w , c w using an approximation method such as the least squares method.

[0042] In this embodiment, an approximate straight line is derived using three measurement points obtained in a state of uniform loading and a state of maximum offset loading at both the front and rear ends. However, measurement points in other states of offset loading may be added, and an approximate straight line may be derived from four or more measurement points. Also, in this embodiment, the measurement points are approximated by a straight line, but it may be configured to approximate by an arbitrary curve such as a quadratic curve or a cubic curve.

[0043] Furthermore, in order to more precisely estimate the loaded weight near the maximum loading capacity (for example, 10 tons) of the special vehicle 1, the number of measurement points in the state of loading the maximum loading capacity may be increased to derive a more accurate approximate curve, or an approximate curve near the maximum loading capacity (for example, approximate curves for 9.8 tons, 9.9 tons, 10.1 tons, 10.2 tons) may be derived. <00​​​​​​​​​​​​​​​​w ,c w It is assumed that the coefficients a are predetermined. w ,b w ,c w This may be determined using actual measured values, or it may be determined using the results of CAE analysis.

[0045] In this embodiment, a coefficient a is applied for each load weight. w ,b w ,c w The configuration was designed to store the equation (a) representing the approximate straight line. 10 x+b 10 y+c 10 The configuration may also involve storing (=0) in the memory unit 102. Furthermore, although the relationship table TB1 was described as defining the relationship between the pitch angle of the truck chassis 2 and the magnitude of the hydraulic pressure, it may also define the relationship between the roll angle of the truck chassis 2 and the magnitude of the hydraulic pressure.

[0046] When the estimation device 100 obtains data on the magnitude of hydraulic pressure (first data) from the pressure gauge 81 and data on the inclination angle of the special vehicle 1 (second data) from the inclinometer 82 via the input unit 104, it estimates the load weight in the cargo box 4 by referring to the relationships stored in the relationship table TB1.

[0047] Figure 8 is an explanatory diagram illustrating the method for estimating the load weight in Embodiment 1. The control unit 101 of the estimation device 100 estimates the load weight in the cargo box 4 based on the distance between the approximate straight line obtained by plotting the relationships stored in the relationship table TB1 on a two-dimensional coordinate plane and the measurement points obtained by plotting the measurement results shown by the first data and the second data on the same two-dimensional coordinate plane.

[0048] Let a be the approximate straight line for load weight W. w x+b w y+c w If we set |a = 0 and the coordinates of the measurement point to (X, Y), then the distance between the approximation line and the measurement point is equal to the length of the perpendicular line drawn from the measurement point to the approximation line, w X+b wY+c w | / (a w 2 +b w 2 ) 1 / 2 It is calculated by [this method].

[0049] When the control unit 101 acquires the first and second data, it identifies the coordinates representing the measurement points and calculates the distance between each approximate line and the measurement point by substituting them into the above calculation formula. Based on the calculated distance, the control unit 101 estimates the load weight in the cargo box 4. For example, as shown in Figure 8, let's consider the case where there is a measurement point between the approximate line for load weight W1 and the approximate line for load weight W2. If the distance from the measurement point to the approximate line for load weight W1 is calculated as L1, and the distance from the measurement point to the approximate line for load weight W2 is calculated as L2, the control unit 101 can estimate the load weight at the measurement point by distributing the distances in a ratio, for example, W1 × L2 / (L1 + L2) + W2 × L1 / (L1 + L2).

[0050] Furthermore, in cases where it is not necessary to precisely estimate the load weight, the control unit 101 may identify the closest approximate straight line to the measurement point and estimate the load weight. For example, in the example shown in Figure 8, the measurement point is closest to the approximate straight line of the load weight W1, so the load weight at the measurement point may be estimated as W1.

[0051] The following describes the procedure for estimating the load weight. Figure 9 is a flowchart illustrating the procedure for estimating the load weight in Embodiment 1. The control unit 101 of the estimation device 100 reads the estimation program PG1 from the storage unit 102 and executes it when the cargo box 4 is positioned at a predetermined dump angle (e.g., 1.0 degree) relative to the truck chassis 2, thereby performing the following processes.

[0052] The control unit 101 acquires first data regarding the magnitude of the hydraulic pressure based on the output from the pressure gauge 81 (step S101). Specifically, the control unit 101 acquires the first data by obtaining the measurement data (hydraulic pressure value of the hydraulic cylinder 52) output from the pressure gauge 81 through the input unit 104.

[0053] The control unit 101 acquires second data regarding the inclination angle of the special vehicle 1 based on the output from the inclinometer 82 (step S102). Specifically, the control unit 101 acquires the second data by acquiring the measurement data (pitch angle and roll angle of the special vehicle 1) output from the inclinometer 82 through the input unit 104.

[0054] The control unit 101 identifies the coordinates of the measurement point on the two-dimensional coordinate plane based on the acquired first and second data (step S103). If X is the magnitude of the hydraulic pressure indicated by the first data and Y is the pitch angle indicated by the second data, the coordinates of the measurement point are expressed as (X,Y).

[0055] The control unit 101 identifies two approximate lines that sandwich the measurement point identified in step S103 (step S104). For example, the control unit 101 can identify two approximate lines that sandwich the measurement point by determining the magnitude of the hydraulic pressure when the pitch angle is X from each approximate line and examining the difference between the magnitude of the hydraulic pressure Y at the measurement point and the magnitude of the hydraulic pressure obtained from the approximate lines.

[0056] The control unit 101 calculates the distance between the measurement point and the two identified approximate lines (step S105). The control unit 101 then determines the coefficient a of each approximate line from the relation table TB1. w ,b w ,c w The data is read, and the coordinates (X,Y) identified in step S103 and the coefficient a that defines each approximation line are read. w ,b w ,c w By substituting these values ​​into the above-mentioned formula, the distance between the measurement point and each approximate line can be calculated.

[0057] The control unit 101 estimates the load weight based on the ratio of the distances from the measurement point to each approximate line (step S106). For example, suppose the approximate line located below the measurement point is the approximate line for load weight W1, and the distance to that approximate line is L1. Also, suppose the approximate line located above the measurement point is the approximate line for load weight W2, and the distance to that approximate line is L2. In this case, the control unit 101 can estimate the load weight by, for example, calculating W1 × L2 / (L1 + L2) + W2 × L1 / (L1 + L2).

[0058] The control unit 101 notifies the estimated load weight (step S107). At this time, the control unit 101 outputs the estimated load weight information from the output unit 105 and displays it on the display device 120. Figure 10 is a schematic diagram showing an example of load weight display. Figure 10 shows an example in which the estimated load weight, load rate, and estimated date and time information are displayed as text information on the display device 120. Here, the estimated load weight is the value of the load weight estimated by referring to the relational table TB1. The load rate is a value calculated as the ratio of the load weight (estimated value) to the upper limit. The estimated date and time is the date and time when the load weight was estimated, and is information obtained, for example, from the built-in clock of the control unit 101. The control unit 101 generates data for the display screen based on the estimated load weight estimated by referring to the relationship table TB1, the load ratio calculated as a percentage of the upper limit, and the date and time information obtained from the built-in clock. By outputting the generated display screen data to the display device 120, the display device 120 can display a screen like the one shown in Figure 10.

[0059] As described above, in Embodiment 1, when the tilt angle of the special vehicle 1 and the hydraulic pressure are obtained, the load weight is estimated by referring to the relationship table TB1 which defines the relationship with the load weight. Therefore, regardless of whether the special vehicle 1 is tilted or not, the load weight can be estimated with high accuracy and the estimated load weight can be reported.

[0060] (Embodiment 2) The method for estimating the load weight in Embodiment 2 will be described below. Figure 11 is an explanatory diagram illustrating the method for estimating the load weight in Embodiment 2. The control unit 101 of the estimation device 100 estimates the load weight in the cargo box 4 based on the distance between the approximate straight line obtained by plotting the relationships stored in the relationship table TB1 on a two-dimensional coordinate plane and the measurement points obtained by plotting the measurement results shown by the first data and the second data on the same two-dimensional coordinate plane.

[0061] In Embodiment 2, instead of using the length of the perpendiculars drawn from the measurement point to each approximate line, a line passing through the measurement point is used. Specifically, the control unit 101 identifies two approximate lines that sandwich the measurement point, and identifies a line segment that passes through the measurement point and connects the two identified approximate lines in the shortest possible distance. The control unit 101 then finds the intersection points of the identified line segment and the approximate lines, and estimates the load weight according to the ratio of the distances from the measurement point to each intersection point.

[0062] As shown in Figure 11, the case where a measurement point exists between the approximate straight line for load weight W1 and the approximate straight line for load weight W2 will be explained. The control unit 101 finds the intersection points of the straight line passing through the measurement point and each approximate straight line, calculates the distance between the intersection points, and identifies the line segment that minimizes the distance between the intersection points. Let P1 be the intersection point with the approximate curve for load weight W1, and P2 be the intersection point with the approximate curve for load weight W2. If the distance from the measurement point to intersection P1 is L1, and the distance from the measurement point to intersection P2 is L2, the control unit 101 can estimate the load weight at the measurement point by distributing the distances in a ratio, for example, W1 × L2 / (L1 + L2) + W2 × L1 / (L1 + L2).

[0063] (Embodiment 3) Embodiment 3 describes a configuration for estimating the load weight by distinguishing between the state in which the cargo box 4 is raised and then stopped, and the state in which the cargo box 4 is lowered and then stopped.

[0064] The inventors of this invention investigated the relationship between the pitch angle of the truck chassis 2 and the hydraulic pressure in detail and found that there is a difference between the hydraulic pressure when the cargo box 4 is raised and then stopped, and the hydraulic pressure when the cargo box 4 is lowered and then stopped. Therefore, in the load weight estimation system of Embodiment 3, the state in which the cargo box 4 is raised and then stopped, and the state in which the cargo box 4 is lowered and then stopped are distinguished, and the load weight is estimated using different relationship tables for each.

[0065] Figure 12 is a block diagram illustrating the configuration of the load weight estimation system in Embodiment 3. The estimation device 100 comprises a control unit 101, a storage unit 102, an operation unit 103, an input unit 104, an output unit 105, and a communication unit 106. The configuration of each of these hardware parts is the same as that described in Embodiment 1, so their description is omitted.

[0066] The memory unit 102 includes a relational table TB10 for stopping upward movement and a relational table TB20 for stopping downward movement. The relational table TB10 for stopping upward movement is a table that stores approximate straight lines for each predetermined load weight based on data of the inclination angle and hydraulic pressure of the special vehicle 1 acquired when the cargo box 4 has stopped after rising, and associates the coefficients of each approximate straight line with the load weight. Similarly, the relational table TB20 for stopping downward movement is a table that stores approximate straight lines for each predetermined load weight based on data of the inclination angle and hydraulic pressure of the special vehicle 1 acquired when the cargo box 4 has stopped after lowering, and associates the coefficients of each approximate straight line with the load weight.

[0067] Figure 13 is a flowchart illustrating the procedure for estimating the load weight in Embodiment 3. The control unit 101 of the estimation device 100 monitors the signal input through the input unit 104 to determine whether or not the weighing switch 89 is turned on (step S301). If it is not turned on (S301: NO), the control unit 101 waits until the weighing switch 89 is turned on.

[0068] When the weighing switch 89 is turned on (S301: YES), the control unit 101 starts the loading weight estimation process. When starting the estimation process, the control unit 101 may instruct the user to adjust the dump angle to a predetermined angle. The predetermined angle is, for example, an angle greater than 0.5 degrees and less than 1.5 degrees. The control unit 101 may give instructions by displaying text information on the display device 120, or by outputting sound from a speaker not shown in the figure. In Embodiment 3, the dump angle is adjusted manually using the operating lever 67.

[0069] The control unit 101 sequentially acquires measurement data of the inclination angle measured over time by the inclinometers 82 and 83 via the input unit 104, and detects the current dump angle based on the acquired measurement data (step S302). The control unit 101 can determine the dump angle by subtracting the inclination angle of the truck chassis 2, obtained as a measurement value from inclinometer 82, from the inclination angle of the cargo box 4, obtained as a measurement value from inclinometer 83. The control unit 101 stores the detected dump angle over time in the storage unit 102.

[0070] The control unit 101 determines whether the dump angle detected in step S302 is greater than the minimum angle θ1 (step S303). The minimum angle θ1 is a value set as the minimum value of the angle range suitable for measuring the load weight of the cargo box 4. An example of the minimum angle θ1 is 0.5 degrees.

[0071] If the control unit 101 determines that the current dump angle is less than or equal to the minimum angle θ1 (S303: NO), it instructs the user to raise the cargo box 4 (step S304). The control unit 101 instructs the user by displaying text information on the display device 120 indicating that the cargo box 4 should be raised. Alternatively, the control unit 101 may instruct the user by outputting an audio message from a speaker (not shown in the diagram) indicating that the cargo box 4 should be raised. Upon receiving the instruction, the user operates the operating lever 67 to raise the cargo box 4 to an appropriate angle and stop it. After giving instructions to the user, the control unit 101 returns to step S302.

[0072] If the control unit 101 determines that the current dump angle is greater than the minimum angle θ1 (S303: YES), it determines whether the current dump angle is less than the maximum angle θ2 (step S305). The maximum angle θ2 is set as the maximum value of the angle range suitable for measuring the load weight of the cargo box 4. An example of the maximum angle θ2 is 1.5 degrees.

[0073] If the control unit 101 determines that the current dump angle is greater than or equal to the maximum angle θ2 (S305: NO), it instructs the user to lower the cargo box 4 (step S306). The control unit 101 instructs the user, for example, by displaying text information on the display device 120 indicating that the cargo box 4 should be lowered. Alternatively, the control unit 101 may instruct the user by outputting an audio message from a speaker (not shown in the diagram) indicating that the cargo box 4 should be lowered. Upon receiving the instruction, the user operates the operating lever 67 to lower the cargo box 4 by an appropriate angle and stop it. After giving instructions to the user, the control unit 101 returns to step S302.

[0074] If the control unit 101 determines that the current dump angle is smaller than the maximum angle θ2 (S305: YES), it refers to the output of the built-in timer to determine whether a predetermined time has elapsed since the dump angle entered the set angle range (step S307). If the predetermined time has not elapsed (S307: NO), the control unit 101 waits until the predetermined time has elapsed.

[0075] If the control unit 101 determines that a predetermined time has elapsed (S307: YES), it determines whether the cargo box 4 was in a stationary state during the period up to the predetermined time (step S308). The control unit 101 can determine whether the cargo box 4 was in a stationary state by checking for any changes in the history data of the dump angle stored in the storage unit 102. If the cargo box 4 was not in a stationary state (S308: NO), the control unit 101 returns to step S302.

[0076] If the cargo box 4 remains stationary until a predetermined time has elapsed (S308: YES), the control unit 101 notifies the user that preparations for weighing the load are complete (step S309). The control unit 101 displays, for example, text information indicating that preparations for weighing the load are complete on the display device 120. Alternatively, the control unit 101 may output an audio message indicating that preparations for weighing the load are complete from a speaker not shown in the diagram.

[0077] Next, the control unit 101 determines whether the cargo box 4 stopped after rising (step S310). The control unit 101 can determine whether the cargo box 4 stopped after rising from the dump angle history data stored in the storage unit 102.

[0078] If the control unit 101 determines that the cargo box 4 has stopped after rising (S310: YES), it selects the relational table TB10 for stopping the upward movement as the table to refer to when estimating the load weight (step S311). On the other hand, if the control unit 101 determines that the cargo box 4 has stopped after descending (S310: NO), it selects the relational table TB20 for stopping the downward movement as the table to refer to when calculating the load weight (step S312).

[0079] The control unit 101 acquires first data (data relating to the magnitude of hydraulic pressure) based on the measurement results of the pressure gauge 81 and second data (data relating to the inclination of the special vehicle 1) based on the measurement results of the inclinometer 82, and estimates the load weight in the cargo box 4 by referring to the relational table TB10 for stopping the upward movement selected in step S311, or the relational table TB20 for stopping the downward movement selected in step S312 (step S313).

[0080] The method described in Embodiment 1 and Embodiment 2 can be used to estimate the load weight. Specifically, the control unit 101 calculates the distance between the measurement points indicated by the first and second data and two approximate straight lines that sandwich these measurement points, and estimates the load weight according to the ratio of the calculated distances.

[0081] Next, the control unit 101 notifies the estimated load weight (step S314). At this time, the control unit 101 outputs the estimated load weight information from the output unit 105 and displays it on the display device 120. The control unit 101 may display the load weight information as text information on the display device 120, or it may use a schematic display method such as a graph display or a meter display. The control unit 101 may also be configured to output the estimated load weight information as sound from a speaker not shown in the diagram. After these processes are completed, the user operates the operation lever 67 to lower the cargo box 4 until the dump angle is 0 degrees. After that, the weighing is completed when the weighing switch 89 is turned off.

[0082] In Embodiment 3, the state in which the cargo box 4 is raised and then stopped, and the state in which the cargo box 4 is lowered and then stopped are distinguished, and different relationship tables are used to estimate the load weight for each state. Therefore, compared to the case in which a common table is used for both states, the decrease in estimation accuracy can be suppressed.

[0083] (Embodiment 4) Embodiment 4 describes a configuration in which the upward stopping operation is performed automatically.

[0084] Figure 14 is a block diagram illustrating the configuration of the load weight estimation system in Embodiment 4. The load weight estimation system according to Embodiment 4 comprises an estimation device 100 and a lifting control device 200 connected to the estimation device 100. The estimation device 100 is the same as that described in Embodiment 3 and comprises a control unit 101, a storage unit 102, an operation unit 103, an input unit 104, an output unit 105, and a communication unit 106. In Embodiment 4, only the relational table TB10 for stopping the lift is used, so the relational table TB20 for stopping the lowering does not need to be stored in the storage unit 102.

[0085] The lifting control device 200 comprises an input unit 201, a control unit 202, and an output unit 203, and controls the lifting and lowering of the cargo box 4 by controlling the operation of the hydraulic mechanism of the special-purpose vehicle 1. The input unit 201 is equipped with an input interface. The input unit 201 receives information output from the estimation device 100, operation information of the operating lever 67, operation information of the PTO switch 72, etc. The information input to the input unit 201 is output to the control unit 202.

[0086] The control unit 202 is configured, for example, by a PLC (Programmable Logic Controller). The control unit 202 generates control signals for raising and lowering the cargo box 4 based on information input through the input unit 201, according to the programmed logic. The control unit 202 outputs the generated control signals to the control valve 63 via the output unit 203. The output unit 203 is equipped with an output interface to which the control valve 63 and the estimation device 100 are connected. In this embodiment 4, the control valve 63 is configured as an electrically controllable electromagnetic control valve.

[0087] In this embodiment, the load weight estimation system is configured to include the estimation device 100 and the lifting control device 200 as separate components, but they may also be configured as an integrated unit.

[0088] Figure 15 is a flowchart illustrating the procedure for estimating the load weight in Embodiment 4. The control unit 101 of the estimation device 100 monitors the signal input through the input unit 104 to determine whether or not the weighing switch 89 is turned on (step S401). If it is not turned on (S401: NO), the control unit 101 waits until the weighing switch 89 is turned on.

[0089] If the metering switch 89 is turned on (S401: YES), the control unit 101 determines whether the PTO switch 72 is on or not (step S402). If the PTO switch 72 is not on (S402: NO), the control unit 101 instructs the user to turn on the PTO switch 72 (step S403) and switches the power transmission destination of the engine 70 to the hydraulic pump 61. The instruction to the user may be given by displaying text information on the display device 120, or by outputting it as sound from a speaker not shown in the figure.

[0090] If the PTO switch 72 is ON (S402: YES), the control unit 101 notifies the user that the dump angle will be adjusted (step S404). The control unit 101 displays, for example, text information indicating that the dump angle will be adjusted on the display device 120. Alternatively, the control unit 101 may output an audio message indicating that the dump angle will be adjusted from a speaker not shown in the diagram.

[0091] Next, the control unit 101 instructs the lifting control device 200 to raise the cargo box 4 (step S405). Specifically, the control unit 101 generates a control signal to instruct the lifting control device 200 to raise the cargo box 4, and outputs the generated control signal to the lifting control device 200 from the output unit 105, thereby giving instructions to the lifting control device 200. The control unit 202 of the lifting control device 200 raises the cargo box 4 by outputting a control signal to the control valve 63 in response to the instruction from the estimation device 100.

[0092] The control unit 101 sequentially acquires measurement data of the inclination angle measured over time by the inclinometers 82 and 83 via the input unit 104, and detects the current dump angle based on the acquired measurement data (step S406).

[0093] The control unit 101 determines whether the dump angle detected in step S406 is greater than the minimum angle θ1 (step S407). The minimum angle θ1 is a value set as the minimum value of the angle range suitable for measuring the load weight of the cargo box 4. An example of the minimum angle θ1 is 0.5 degrees.

[0094] If the control unit 101 determines that the current dump angle is less than or equal to the minimum angle θ1 (S407: NO), it returns the process to step S405 and continues the upward control of the cargo box 4.

[0095] If the control unit 101 determines that the current dump angle is greater than the minimum angle θ1 (S407: YES), it determines whether the current dump angle is less than the maximum angle θ2 (step S408). The maximum angle θ2 is set as the maximum value of the angle range suitable for measuring the load weight of the cargo box 4. An example of a maximum angle θ2 is 1.5 degrees.

[0096] If the control unit 101 determines that the current dump angle is greater than or equal to the maximum angle θ2 (S408: NO), it reports an error (step S409) because the tilt angle of the cargo box 4 is outside the angle range suitable for measuring the load weight, and terminates the process according to this flowchart. After reporting the error, the control unit 101 may instruct the lifting control device 200 to lower the cargo box 4.

[0097] If the control unit 101 determines that the current dump angle is less than the maximum angle θ2 (S408: YES), it instructs the lifting box 4 to stop after it has been raised (step S410). Specifically, the control unit 101 generates a control signal to instruct the lifting box 4 to stop, and outputs the generated control signal to the lifting control device 200 from the output unit 105, thereby giving instructions to the lifting control device 200. The control unit 202 of the lifting control device 200 stops the lifting box 4 by outputting a control signal to the control valve 63 in response to the instruction from the estimation device 100.

[0098] Next, the control unit 101 notifies the user that preparations for weighing the load are complete (step S411). For example, the control unit 101 displays text information indicating that preparations for weighing the load are complete on the display device 120. Alternatively, the control unit 101 may output audio information indicating that preparations for weighing the load are complete from a speaker not shown in the diagram.

[0099] Next, the control unit 101 sets the relationship table TB10 for stopping the lift as a table to be referenced when estimating the load weight (step S412). The control unit 101 acquires first data (data related to the magnitude of hydraulic pressure) based on the measurement result of the pressure gauge 81 and second data (data related to the inclination of the special vehicle 1) based on the measurement result of the inclinometer 82, and estimates the load weight in the cargo box 4 by referring to the relationship table TB10 for stopping the lift set in step S412 (step S413).

[0100] The method described in Embodiment 1 and Embodiment 2 can be used to estimate the load weight. Specifically, the control unit 101 calculates the distance between the measurement points indicated by the first and second data and two approximate straight lines that sandwich these measurement points, and estimates the load weight according to the ratio of the calculated distances.

[0101] Next, the control unit 101 notifies the estimated load weight (step S414). At this time, the control unit 101 outputs the estimated load weight information from the output unit 105 and displays it on the display device 120. The control unit 101 may display the load weight information as text information on the display device 120, or it may use a schematic display method such as a graph display or a meter display. Alternatively, the control unit 101 may be configured to output the estimated load weight information as audio information from a speaker not shown in the diagram.

[0102] The control unit 101 may estimate the load weight and notify the user, and then instruct the lifting control device 200 to lower the cargo box 4. The control unit 202 of the lifting control device 200 will lower the cargo box 4 by outputting a control signal to the control valve 63 in response to the instruction from the estimation device 100.

[0103] When manually measuring the load weight, it is necessary to adjust the dump angle to a predetermined angle (for example, 1.0 degree), which can be cumbersome for the user. In contrast, in this embodiment, the load weight can be automatically measured by operating the weighing switch 89, thus reducing the inconvenience of operation.

[0104] (Embodiment 5) Embodiment 5 describes a configuration in which the load weight is estimated using a common relationship table TB30, whether the cargo box 4 is raised and then stopped, or lowered and then stopped.

[0105] Figure 16 is a block diagram illustrating the configuration of the load weight estimation system in Embodiment 5. The estimation device 100 comprises a control unit 101, a storage unit 102, an operation unit 103, an input unit 104, an output unit 105, and a communication unit 106. The configuration of each of these hardware parts is the same as that described in Embodiment 1, so their description is omitted.

[0106] The memory unit 102 includes a common relationship table TB30 for both the case where the cargo box 4 is raised and then stopped, and the case where the cargo box 4 is lowered and then stopped. The configuration of the relationship table TB30 is the same as the relationship table TB1 described in Embodiment 1, and it stores the relationship between the tilt angle of the special vehicle 1 and the magnitude of the hydraulic pressure when the weight and position of the load are changed, in relation to the weight of the load.

[0107] In Embodiment 5, it is assumed that the relationship between the hydraulic pressure value measured after the cargo box 4 stops rising and the hydraulic pressure value measured after the cargo box 4 stops descending is known in advance. For example, assuming the same measurement conditions, it is assumed that there is a relationship between the hydraulic pressure value PV1 measured after the cargo box 4 stops rising and the hydraulic pressure value PV2 measured after the cargo box 4 stops descending, such that PV1 = PV2 + ΔPV. ΔPV is the differential pressure between PV1 and PV2, and is assumed to be known in Embodiment 5. The relational expression showing this relationship is stored in the memory unit 102.

[0108] When the control unit 101 obtains the hydraulic pressure value (=PV1) and inclination angle measured after the ascent stops, it estimates the load weight by referring to the relational table TB30 based on the obtained hydraulic pressure value and inclination angle. On the other hand, when the control unit 101 obtains the hydraulic pressure value (=PV2) and inclination angle measured after the descent stops, it corrects the hydraulic pressure value PV2 according to the relational formula stored in the memory unit 102. That is, the control unit 101 corrects the obtained hydraulic pressure value PV2 by adding the difference ΔPV. Based on the corrected hydraulic pressure value (=PV2+ΔPV) and inclination angle, the control unit 101 estimates the load weight by referring to the relational table TB30.

[0109] Figure 17 is a flowchart illustrating the procedure for estimating the load weight in Embodiment 5. The control unit 101 of the estimation device 100 completes the weighing preparation in the same procedure as S301 to S309 in the flowchart shown in Figure 13, and notifies the user that preparation for weighing the load weight is complete (steps S501 to S509). After the weighing preparation is complete, the loading operation is performed. The control unit 101 acquires first data (oil pressure value) based on the measurement result of the pressure gauge 81 and second data (tilt angle of the special vehicle 1) based on the measurement result of the inclinometer 82 as needed.

[0110] After notifying the user that preparations for weighing the load are complete, the control unit 101 determines in the processes of S501 to S508 whether the cargo box 4 has stopped after rising (step S510). If the control unit 101 determines that the cargo box 4 has stopped after rising (S510: YES), it estimates the load weight by referring to the relationship table TB30 based on the acquired hydraulic pressure value and inclination angle (step S511). The method for estimating the load weight using the relationship table TB30 is the same as in Embodiment 1.

[0111] On the other hand, if the control unit 101 determines that the cargo box 4 has stopped after lowering (S510: NO), it adds the differential pressure ΔPV to the hydraulic pressure value P2 after the lowering stops (step S512). Then, the control unit 101 proceeds to step S511 and estimates the load weight by referring to the relationship table TB30 based on the hydraulic pressure value with the differential pressure added (=PV2+ΔPV) and the inclination angle (step S511). The method for estimating the load weight using the relationship table TB30 is the same as in Embodiment 1.

[0112] Next, the control unit 101 notifies the estimated load weight (step S513). At this time, the control unit 101 outputs the estimated load weight information from the output unit 105 and displays it on the display device 120. The control unit 101 may display the load weight information as text information on the display device 120, or it may use a schematic display method such as a graph display or a meter display. The control unit 101 may also be configured to output the estimated load weight information as sound from a speaker not shown in the diagram. After these processes are completed, the user operates the operation lever 67 to lower the cargo box 4 until the dump angle is 0 degrees. After that, the weighing is completed when the weighing switch 89 is turned off.

[0113] As described above, in Embodiment 5, the relationship between the hydraulic pressure value measured after the upward movement stops and the hydraulic pressure value measured after the downward movement stops is known. For example, the hydraulic pressure value measured after the downward movement stops can be corrected to be equivalent to the hydraulic pressure value measured after the upward movement stops under the same conditions. Therefore, it is no longer necessary to prepare two types of relationship tables (a relationship table for upward movement stops and a relationship table for downward movement stops) to estimate the load weight from the hydraulic pressure value, and the load weight can be estimated even with an estimation device 100 that has a relatively small storage capacity in the memory unit 102.

[0114] In this embodiment, the differential pressure is added to the hydraulic pressure value obtained after the descent stops, but it may also be configured to subtract the differential pressure from the hydraulic pressure value obtained after the ascent stops. Furthermore, the hydraulic pressure value may be corrected using any relational expression, not limited to adding (or subtracting) the differential pressure.

[0115] (Embodiment 6) Embodiment 6 describes a configuration in which the load weight is estimated using a learning model.

[0116] Figure 18 is a schematic diagram showing an example configuration of the learning model LM1. In this embodiment, the learning model LM1 is, for example, a support vector regression model and comprises an input layer into which various data are input, an intermediate layer including a kernel that performs predetermined calculations based on the data input to the input layer, and an output layer that combines the outputs from the intermediate layer and outputs the calculation results.

[0117] The input, hidden, and output layers of the LM1 learning model each contain one or more nodes, and the nodes in each layer are connected to the nodes in the preceding and succeeding layers by coupling weights in a unidirectional direction. In a nonlinearly extended support vector machine using the kernel trick, the coupling weights from the hidden layer to the output layer are adaptively determined through learning. On the other hand, the coupling weights from the input layer to the hidden layer are fixed and are mechanically determined from the training data.

[0118] The input layer of the learning model LM1 receives the first data (data related to the magnitude of hydraulic pressure) and the second data (data related to the inclination of special vehicle 1). The data input to the input layer is weighted by the coupling loads determined using the training data and output to the hidden layer. The hidden layer performs calculations using kernels based on the data input from the input layer. The data calculated in each kernel of the hidden layer is weighted by the coupling loads determined by learning and output to the output layer. The output layer combines the data input from the hidden layer to output the calculation result regarding the load weight.

[0119] Here, the calculation result output by the output layer may be an estimated value of the load weight, or it may be the probability that the load weight is a certain value. In the latter case, the output layer is composed of multiple nodes, and the first node should output the probability that the load weight is 1 ton, the second node the probability that the load weight is 2 tons, ..., and the Nth node (where N is an integer greater than or equal to 2) the probability that the load weight is N tons, and so on, outputting the probability that the load weight is a certain value.

[0120] The learning model LM1 may be provided in the memory unit 102 of the estimation device 100, or it may be provided in an external server device that is communicatively connected to the estimation device 100.

[0121] The estimation device 100 can estimate the load weight by inputting data obtained during the loading operation into the learning model LM1 and obtaining the calculation results from the learning model LM1.

[0122] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims, not in the sense described above, and all modifications within the sense and scope equivalent to the claims are intended.

[0123] For example, in this embodiment, a dump truck was described as a special-purpose vehicle 1, which includes an estimation device 100 for estimating the load weight, a display device 120 for notifying information regarding the load weight estimated by the estimation device 100, and a dumping device 3. However, the present invention is not limited to dump trucks and can be applied to various special-purpose vehicles equipped with a dumping device having a hydraulic cylinder. For example, it can be applied to special-purpose vehicles such as dump-discharge type suction vehicles, dump-discharge type refuse collection vehicles, and container detachment vehicles equipped with a cargo handling arm. [Explanation of symbols]

[0124] 1. Special-purpose vehicle 2 Truck Chassis 3. Dumping device 4 packing boxes 5. Hoist mechanism 20 Cab 21 Chassis Frame 22F front wheel 22R rear wheel 23F,23R Axle 30 Subframes 81 Pressure gauge 82 Inclinometer (Chassis) 83 Inclinometer (packing box) 100 Estimator 101 Control Unit 102 Storage section 103 Operation section 104 Input section 105 Output section 106 Communications Department PG1 Estimation Program TB1 Relationship Table

Claims

1. Regarding a special-purpose vehicle equipped with a hydraulic actuator for raising and lowering a cargo box, a first acquisition unit acquires first data relating to the magnitude of the hydraulic pressure from a pressure gauge that measures the magnitude of the hydraulic pressure acting on the hydraulic actuator, A second acquisition unit that acquires second data indicating the inclination angle from an inclinometer that measures the inclination angle of the truck chassis in the aforementioned special-purpose vehicle, A storage unit stores multiple relationships between the tilt angle and the magnitude of the hydraulic pressure when the weight and position of the cargo are changed between an evenly loaded state where the cargo is evenly distributed on the cargo box and a maximum unevenly loaded state where the cargo is most unevenly distributed on the cargo box, in relation to the weight of the cargo. When the first data and the second data are obtained, an estimation unit estimates the load weight in the cargo box by referring to the relationship stored in the storage unit. A system for estimating the load weight of specially equipped vehicles.

2. The estimation unit estimates the load weight based on the distance between the approximation curve obtained by plotting the relationship on a two-dimensional coordinate plane and the measurement points obtained by plotting the measurement results indicated by the first data and the second data on the two-dimensional coordinate plane. The load weight estimation system according to claim 1.

3. The estimation unit estimates the load weight by identifying the approximation curve closest to the measurement point. The load weight estimation system according to claim 2.

4. The estimation unit identifies two approximation curves that sandwich the measurement point, and estimates the load weight according to the ratio of the distances from the measurement point to the two identified approximation curves. The load weight estimation system according to claim 2.

5. The estimation unit calculates the ratio of the lengths of the perpendiculars drawn from the measurement point to the two approximation curves, and estimates the load weight according to the calculated ratio. The load weight estimation system according to claim 4.

6. The estimation unit identifies a line segment that passes through the measurement point and connects the two approximation curves in the shortest possible time, finds the intersection point between the identified line segment and each approximation curve, calculates the ratio of the distances from the measurement point to each intersection point, and estimates the load weight according to the calculated ratio. The load weight estimation system according to claim 4.

7. Regarding a specially equipped vehicle that has a hydraulic actuator for raising and lowering a cargo box, first data relating to the magnitude of the hydraulic pressure acting on the hydraulic actuator is obtained from a pressure gauge that measures the magnitude of the hydraulic pressure acting on the hydraulic actuator. From an inclinometer that measures the inclination angle of the truck chassis in the aforementioned special-purpose vehicle, a second data indicating the inclination angle is obtained. When the first and second data are obtained, the system estimates the load weight in the cargo box by referring to a storage unit that stores multiple relationships between the tilt angle and the magnitude of the hydraulic pressure when the weight and position of the cargo are changed between an evenly loaded state where the cargo is evenly distributed on the cargo box and a maximum unevenly loaded state where the cargo is most unevenly distributed on the cargo box, in relation to the weight of the cargo. A method for estimating the load weight of a specially equipped vehicle, with the processing performed by a computer.

8. On the computer, Regarding a specially equipped vehicle that has a hydraulic actuator for raising and lowering a cargo box, first data relating to the magnitude of the hydraulic pressure acting on the hydraulic actuator is obtained from a pressure gauge that measures the magnitude of the hydraulic pressure acting on the hydraulic actuator. From an inclinometer that measures the inclination angle of the truck chassis in the aforementioned special-purpose vehicle, a second data indicating the inclination angle is obtained. When the first and second data are obtained, the system estimates the load weight in the cargo box by referring to a storage unit that stores multiple relationships between the tilt angle and the magnitude of the hydraulic pressure when the weight and position of the cargo are changed between an evenly loaded state where the cargo is evenly distributed on the cargo box and a maximum unevenly loaded state where the cargo is most unevenly distributed on the cargo box, in relation to the weight of the cargo. A computer program designed to execute a process.

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