JP6012523B2 - Construction vehicle - Google Patents

Description

  The present invention relates to a construction vehicle used in a mine or a construction site.

  In a construction vehicle and an industrial vehicle having wheels (hereinafter sometimes referred to as “vehicle”), the vehicle speed (vehicle speed) may be calculated by multiplying the rotation speed of the wheel by the radius of the wheel. In this method, there is a problem that the radius of the wheel changes due to a load load or aging deterioration, and the accuracy of the vehicle speed deteriorates. In order to solve these problems, there is a method of correcting the vehicle speed by estimating or measuring the vehicle weight (loading load) and learning the correlation between the vehicle weight and the wheel radius. In addition, there is a case where a method of correcting the wheel speed due to a secular change of the wheel radius using a sensor such as a GPS receiver is used.

  For example, Japanese Patent Laid-Open No. 2000-121357 discloses a method of storing correction values due to changes in vehicle weight and wheels when the load is large, calculating the correction value from the vehicle weight, and outputting the vehicle speed with high accuracy. Is disclosed. Japanese Patent Application Laid-Open No. 5-1119046 also discloses a method for creating map data of a loaded load and a correction coefficient. Similarly, Japanese Translation of PCT International Application No. 2008-523360 discloses a method for directly calculating the effective radius of a tire from the load and the pressure of the tire. Further, correction of the wheel speed due to changes over time in the wheel radius, etc. discloses a method of calculating and correcting the moving distance of the vehicle using other sensors. Japanese Patent Application Laid-Open No. 2009-210499 discloses an in-vehicle camera. The moving distance of the feature is calculated and the vehicle speed is corrected.

JP 2000-121357 A Japanese Patent Application Laid-Open No. 5-119046 Special table 2008-523360 gazette JP 2009-210499A

  By the way, unlike general vehicles that are supposed to travel on paved roads with stable road surface conditions, construction vehicles (or industrial vehicles) including dump trucks often travel on unpaved ground, and the road surface conditions change. It is often used in an easy environment. When the road surface condition changes in this way (especially when the coefficient of friction, viscosity, etc. change greatly), even if the wheel radius does not change due to the load, etc., as described above, it is based on the wheel speed. The accuracy of the vehicle speed calculated in this way may deteriorate. Changes in road surface conditions are not as easy to detect as changes in load and wheel radius, making it difficult to correct the vehicle speed compared to the above methods.

  In this regard, the wheel speed can be corrected in an environment where the moving distance of the vehicle can be calculated by receiving a radio wave signal from a GPS satellite with a GPS receiver. It is also possible to directly correct the wheel speed by calculating the speed from the Doppler frequency of the radio wave from the GPS satellite.

  However, when traveling in a place where it is difficult to receive a signal from a GPS satellite, an accurate vehicle speed cannot be calculated, so the travel distance is not always obtained at the desired timing. For example, in an open pit site where excavation of ore is performed while digging a mine in a roughly stepped shape (mortar shape) toward the bottom, the bottom may reach a depth of several hundred meters from the ground surface. Initially, there are often areas where GPS satellite radio waves do not reach or areas where radio wave supplementation conditions deteriorate (for example, areas where the number of satellites capable of receiving radio waves is small). For this reason, the calculation accuracy of the speed of the vehicle traveling in the region must be deteriorated.

  An object of the present invention is to provide a construction vehicle capable of calculating an accurate vehicle speed even in a situation where position measurement by GPS is difficult.

In order to achieve the above object, according to the present invention, in a construction vehicle having a plurality of wheels, an acceleration sensor that detects at least a longitudinal acceleration of the construction vehicle, and an angular velocity that detects at least a pitch angular velocity and a yaw angular velocity of the construction vehicle. A speed change detecting unit that calculates an estimated value of a change in vehicle speed of the construction vehicle based on the sensor, the longitudinal acceleration, the pitch angular velocity, and the yaw angular velocity; and an estimated value of the change in vehicle speed over time And a time correction coefficient of the wheel speed of at least one wheel of the plurality of wheels, a speed correction coefficient of the at least one wheel speed is calculated, and the at least one wheel speed is corrected by the speed correction coefficient. And a speed calculation unit for calculating the vehicle speed.

  According to the present invention, an accurate vehicle speed can be calculated even in a situation where position measurement by GPS is difficult.

1 is an overall configuration diagram of a construction vehicle according to an embodiment of the present invention. 1 is an overall configuration diagram of a vehicle speed calculation system according to an embodiment of the present invention. The process flowchart of a vehicle speed change detection part. The calculation flowchart of the wheel speed correction coefficient of the object wheel in step 209 of FIG. The figure showing the table of a slip ratio and a road surface friction coefficient. The figure showing the table of a road surface pattern and rolling resistance value. The figure showing the table of rolling resistance. The figure which modeled the vehicle body in turning and represented the relation between a steering angle and a turning radius. The processing flowchart of the vehicle speed calculating part which concerns on the 1st Embodiment of this invention. The process flowchart of the vehicle speed calculating part which concerns on the 2nd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an overall configuration diagram of a construction vehicle according to an embodiment of the present invention. Here, as a construction vehicle, a dump truck (a so-called mine dump) that is a large transport vehicle that transports crushed stones mined in an open-pit mining site, a quarry, a mine, or the like will be described as an example.

  A dump truck (vehicle) 1 shown in FIG. 1 includes a vehicle body 2 having a sturdy frame structure, a vessel (loading platform) 3 mounted on the vehicle body 2 so as to be able to undulate, a front wheel 101 mounted on the vehicle body 2, and The rear wheel 104 is mainly provided.

  The vessel 3 is a container provided for loading a load such as a crushed stone, and is connected to the vehicle body 2 via a pin coupling portion 4 and the like so as to be raised and lowered. Two undulation cylinders 7 are installed at a lower portion of the vessel 3 at a predetermined interval in the width direction of the vehicle. When pressure oil is supplied to and discharged from the undulation cylinder 7, the undulation cylinder 7 extends and contracts, and the vessel 3 is undulated. A flange 6 is provided on the upper front side of the vessel 3.

  The heel part 6 has a function of protecting the cab 5 installed on the lower side thereof (that is, the front part of the vehicle body 2) from scattered objects such as rocks and protecting the cab 5 when the vehicle falls. Yes. Inside the cab 5, a steering handle, a display device for displaying the speed of the vehicle, an accelerator pedal, a brake pedal, and the like (not shown) are installed.

  The front wheels 101 are steered wheels that are steered based on a steering angle that is input via a handle or the like, and are rotatably mounted on the left and right in front of the vehicle body 2. The front wheel 101 is a driven wheel. The rear wheels 104 are drive wheels and are rotatably mounted on the left and right sides of the vehicle body 2. In the following description, the front wheel 101 and the rear wheel 104 are described as being mounted one by one on the left and right, but two or more wheels may be handled as a set of wheels.

  FIG. 2 is an overall configuration diagram of the vehicle speed calculation system according to the embodiment of the present invention mounted on the vehicle shown in FIG. In addition, the same code | symbol is attached | subjected to the same part as the previous figure, and description is abbreviate | omitted (the following figure is also the same).

  The vehicle speed calculation system shown in this figure is connected to the wheel speed sensors 121 of the left and right front wheels 101 and detects the steering angle of the front wheels 101 and the front wheel speed detector 102 that outputs the rotation speed (wheel speed) of each front wheel 101. In addition to the steering angle detector 103, the rear wheel speed detector 105 connected to the wheel speed sensor 124 of the left and right rear wheels 104 and outputting the rotation speed (wheel speed) of each rear wheel 104, and the left and right rear wheels 104 A driving torque detector 106 for detecting each of the generated driving torques, a vehicle weight detector 107 for detecting the weight of the vehicle body (total weight including the load in the vessel 3), an acceleration sensor connected to the inertial sensor, Inertial measurement unit 108 that detects angular velocity, vehicle speed change detection unit 109 that calculates an estimated value of time change (driving acceleration) of vehicle speed (vehicle speed), and an estimated value of driving acceleration and wheel speed. And a vehicle speed calculation unit 110 that calculates and outputs a vehicle speed are. Each of the above parts is connected by a CAN (Control Area Network) 111, and data input / output to each part is freely configured.

  The vehicle speed change detection unit 109 includes a memory (storage device) 112 for storing various information necessary for vehicle speed calculation processing, including past information calculated in the detection unit 109. Further, the left and right rear wheels 104 according to the present embodiment are driven by driving torques output from different electric motors, and the driving torque detector 106 detects the driving torque of each electric motor. Furthermore, the vehicle speed calculation system includes a position detection unit 114 that is connected to a vehicle position sensor 113 such as a GPS receiver and detects the vehicle position. In addition, each part 103,106,107,108,109,110,114 included in the area | region enclosed with the broken line may be unitized.

  The vehicle speed calculation unit 110 periodically calculates and outputs the speed of the own vehicle. The calculation method of the vehicle speed is shown below.

  From the front wheel speed detection unit 102 and the rear wheel speed detection unit 105, the rotation speed of each wheel 101.104 is periodically output to the CAN 111. Wheel speed sensors (rotation speed sensors) 121 and 124 attached to the front wheel 101 and the rear wheel 104 can detect the rotation of a wheel such as a pulse encoder in detail, and can also detect a rotation speed smaller than one rotation. The front wheel speed detection unit 102 and the rear wheel speed detection unit 105 output the rotation speeds of the left and right wheels.

  Next, the steering angle detection unit 103 detects the steering angle of the front wheels 101 and periodically outputs it to the CAN 111. The steering angle has different outputs for the left and right wheels of the front wheel 101. Next, the magnitude of the driving torque applied to the left and right rear wheels 104 is detected from the driving torque detector 106 and is periodically output to the CAN 111.

  The vehicle weight detection unit 107 periodically measures the load of the load in the vessel 3 by a known method (for example, see Japanese Patent No. 4149874), and the value obtained by adding the vehicle body weight to the load is used as the vehicle weight. Output to CAN111 periodically.

  From the inertial measurement unit 108, a longitudinal acceleration (vertical acceleration), a lateral acceleration (lateral acceleration), a vertical acceleration and a vertical acceleration of the vehicle body are obtained from a triaxial angular velocity sensor and a triaxial acceleration sensor fixed to the vehicle body. The acceleration and angular velocity (roll angular velocity, pitch angular velocity, yaw angular velocity) corresponding to each of the three axes are periodically output to the CAN 111.

  From the information flowing in the CAN 111, the vehicle speed change detection unit 109 estimates a time change in the vehicle speed, thereby calculating a correction coefficient for the wheel speed and outputs it to the CAN 111. FIG. 3 shows a correction coefficient calculation processing flow in the vehicle speed change detection unit 109.

  In step 201 in FIG. 3, the vehicle speed change detection unit 109 is activated at regular intervals, and the process proceeds to step 202. In step 202, the acceleration and angular velocity of the vehicle body measured by the inertia measuring unit 108 are acquired, and the process proceeds to step 203. In step 203, the average value of the front wheel speed is obtained, and it is determined whether the absolute value is larger than 0, that is, whether the vehicle is moving. If it is determined that the vehicle is moving, the process proceeds to step 204. If it is determined that the vehicle is not moving, the process proceeds to step 206.

  In step 206 (when it is determined in step 203 that the vehicle is not moving), the vehicle body inclination angle is calculated. The vehicle body inclination angle is obtained by calculating how much the vehicle body axis representing the longitudinal direction of the vehicle body is inclined with respect to the direction in which the gravitational acceleration is applied. The vehicle body inclination angle can be obtained by the following equation (1) based on the vertical acceleration among the accelerations acquired in step 202. When the calculation of the vehicle body inclination angle is finished in step 206, the processing of the vehicle speed change detection unit 109 is finished.

  On the other hand, in step 204 (when it is determined in step 203 that the vehicle is moving), the vehicle body inclination angle calculated at the previous start (one start cycle before) from the memory 112 in the vehicle speed change detection unit 109 is calculated. Acquire and go to step 205.

  In step 205, the vehicle body inclination angle is calculated from the previous vehicle body inclination angle acquired in step 204 and the vehicle body pitch angular velocity output from the inertia measurement unit 108 and acquired via the CAN 111 according to the following equation. It should be noted that the “start cycle” in the following formula (2) is a fixed time indicating the cycle at which the vehicle speed change detection unit 109 is started. When the vehicle body inclination angle is calculated, the routine proceeds to step 207.

  In step 207, the vehicle weight output from the vehicle weight detector 107 is acquired via the CAN 111, and the process proceeds to step 208. Note that the vehicle weight in step 207 is the total weight of the vehicle including the load in the vessel 3.

  In step 208, the inclination resistance is obtained from the vehicle body inclination angle obtained in step 205 and the vehicle weight obtained in step 207, and the routine proceeds to step 209. The slope resistance can be obtained from the following equation (3).

  Next, in step 209, a wheel speed correction coefficient related to one of the plurality of wheels 101 and 104 mounted on the vehicle 1 is calculated. In the following, the wheel for which the wheel speed correction coefficient is calculated may be referred to as “target wheel”. The calculation method of the wheel speed correction coefficient of the target wheel by the vehicle speed change detection unit 109 in step 209 is shown in the flowchart of FIG.

  As shown in FIG. 4, the vehicle speed change detection unit 109 first calculates a load applied to the target wheel from the vehicle weight obtained in Step 207 in Step 301. In the present embodiment, the load applied to the target wheel is calculated based on the ratio of the vehicle weight (total vehicle weight) acting on each wheel. Next, an example of the calculation procedure will be described.

  First, a formula to be used is determined depending on whether the target wheel is the front wheel 101 or the rear wheel 104, and the load applied to the front wheel side or the rear wheel side of the total vehicle weight (“load applied to the left and right front wheels” or “ Calculate the load applied to the rear wheel "). When the target wheel is any of the left and right wheels of the front wheel 101, the following equation (4) is used. When the target wheel is any of the left and right wheels of the rear wheel 104, the following equation (5) is used. In the following formulas (4) and (5), “the ratio of the front wheels” and “the ratio of the rear wheels” are values indicating the ratio of the load applied to the left and right front wheels 101 and the left and right rear wheels 104. It is assumed that a predetermined value is used.

  Next, depending on whether the target wheel corresponds to the left wheel or the right wheel, the ratio of the load applied to the left and right wheels to the right wheel or the left wheel ("Right wheel ratio" or "Left wheel ratio") Is calculated. At that time, first, based on the lateral acceleration output value output from the inertia measuring unit 108 in step 202, the vehicle body lateral inclination angle is calculated by the following equation (6). Next, one of the following formulas (7) and (8) is selected according to whether the target wheel is the left wheel or the right wheel. Then, the “right wheel ratio” or “left wheel ratio” is calculated from the vehicle body lateral inclination angle calculated earlier and the maximum lateral inclination angle preset for each vehicle.

  Then, one of the following (9) to (12) is selected according to whether the target wheel corresponds to one of the front and rear wheels or further to the left and right wheels, and the selected formula and the previous calculation result Based on the above, the load applied to the target wheel is calculated. In addition to this method, any similar method may be used as long as the load applied to each wheel is measured and calculated.

  Once the load applied to the target wheel is obtained, the rotation speed of the target wheel is acquired from the CAN 111, and the wheel speed correction coefficient of the target wheel calculated at the previous activation is acquired from the memory 112 (step 302). Go to 303. In step 303, the air resistance is obtained based on the following equation (13) from the rotation speed of the target wheel obtained in step 302 and the wheel speed correction coefficient of the previous target wheel, and the process proceeds to step 304.

  In step 304, a road surface friction coefficient μ is obtained. Since the road surface friction coefficient μ is determined by the slip ratio, first, the slip ratio is calculated.

  The slip ratio can be obtained by the following equation (14). In the following formula (14), “front wheel rotation speed” and “rear wheel rotation speed” are “right wheel rotation speed” and “rear wheel rotation speed” when the target wheel is the right wheel. “Wheel rotation speed” is indicated. In the case of the left wheel, “left wheel front wheel rotation speed” and “left wheel rear wheel rotation speed” are indicated. Further, the following formula (14) is an expression when the driving wheel is the rear wheel and the driven wheel is the front wheel, and it goes without saying that the front and rear are reversed when the front wheel is the driving wheel and the rear wheel is the driven wheel. Nor.

  Next, the road surface friction coefficient μ is determined from the slip ratio. In the present embodiment, a table defining the relationship between the slip ratio and the road surface friction coefficient μ is stored in the memory 112, and the road surface friction coefficient μ is obtained from the slip ratio based on the table. FIG. 5 shows a table of road surface friction coefficient μ and slip ratio.

In the table shown in FIG. 5, the relationship between the slip ratio 401 and the road surface friction coefficient μ 402 is set for each of a plurality of road surface patterns (road surface states) 403. Specific examples of the road surface pattern 403 (namely, road surface A, road surface B,..., Road surface N in FIG. 5) include a normal dry road surface, a wet road surface, and a road surface whose surface is made of gravel. As the road surface friction coefficient μ for the slip ratio calculated by the above equation (14), the most appropriate one is selected from the plurality of road surface patterns 403. Specific examples of the method of selecting the road surface pattern 403 include (I) selection based on vehicle body acceleration at a predetermined slip ratio μ _Thrhld , and (II) selection based on Bayesian estimation. Note that values not in the table of FIG. 5 may be calculated by linear interpolation. The road surface friction coefficient μ can also be calculated by maximum likelihood estimation such as a Kalman filter or an optimum filter.

  When the road surface friction coefficient μ is calculated, the road surface resistance is calculated in step 305. The road surface resistance can be obtained based on the following formula (15) from the road surface friction coefficient μ selected in step 304, the rolling resistance coefficient that is a parameter value, and the load applied to the target wheel calculated in step 301. The “rolling resistance coefficient” in the following formula (15) is a numerical value selected based on the road surface pattern selected in step 304, and in the present embodiment, based on a table prepared in advance in the memory 112. Selected. FIG. 6 shows an example of a table showing the relationship between the rolling resistance coefficient and the road surface pattern.

  When the road surface resistance is calculated, the routine proceeds to step 306. In step 306, the driving torque output from the driving torque detector 106 and acquired via the CAN 111, the road surface resistance calculated in step 305, the air resistance calculated in step 303, and the slope calculated in step 208 Based on the resistance and the load applied to the target wheel obtained in step 301, an estimated value of the driving acceleration (time change of the vehicle speed) of the target wheel is obtained by the following equation. The “drive torque” in the following formula uses the drive torque applied to the right rear wheel when the target wheel is the right wheel, and uses the drive torque applied to the left rear wheel when the target wheel is the left wheel. To do.

  In step 307, from the driving acceleration calculated in step 306, the wheel speed of the target wheel acquired in step 302, and the value of the wheel speed of the target wheel before one activation cycle stored in the memory 112, the following equation is obtained. The wheel speed correction coefficient of the target wheel is obtained.

  When the wheel speed correction coefficient is calculated in step 307, the process returns to the flowchart of FIG. 3 to determine whether or not the wheel speed correction coefficient has been calculated for all the wheels (step 210). If there is a wheel for which the wheel speed correction coefficient has not been calculated, the process returns to step 301 and is calculated by the processing from step 302 onward. On the other hand, when the wheel speed correction coefficient is calculated for all the wheels, the wheel speed correction coefficient related to each wheel is output to the CAN 111 (step 211), and the processing of the vehicle speed change detection unit 109 is ended.

Next, a processing flow of the vehicle speed calculation unit 110 is shown in FIG.
As shown in FIG. 7, in step 601, the vehicle speed calculation unit 110 is activated at a regular period (activation period), and the process proceeds to step 602. In step 602, the wheel speed correction coefficients of the wheels 101 and 104 output by the vehicle speed change detection unit 109 are acquired from the CAN 111, and the process proceeds to step 603. In step 603, the steering angle detected by the steering angle detection unit 103 is acquired from the CAN 111, and the process proceeds to step 604.

  In step 604, it is determined whether or not the absolute value of the steering angle is equal to or smaller than a threshold value α. If the absolute value of the steering angle is equal to or smaller than the threshold value α, it is determined that the vehicle body is not turning, and the process proceeds to step 605. If it is larger than the threshold value α, it is determined that the vehicle body is turning, and the routine proceeds to step 609. The threshold value α is a preset value (for example, 15 degrees), and is preferably set so as not to be determined to turn within the range of play of the steering wheel, for example.

  In step 605, the wheel speed (wheel rotation speed) of the left and right front wheels 101 output from the front wheel speed detection unit 102 is acquired via the CAN 111, and the process proceeds to step 606. In step 606, since it is determined in step 604 that the vehicle body is not turning, the front wheel speed (front wheel rotation speed) obtained in step 605 and the wheel speed correction coefficient of each wheel obtained in step 602 are determined. Based on the following formula (18), the average value of the front wheel speed is obtained, and the routine proceeds to step 607.

  In step 607, the average value of the front wheel speed acquired in step 606 is set as the vehicle speed that is the speed of the vehicle (vehicle body) (the following equation (19)), and the process proceeds to step 608.

  If it is determined in step 604 that the vehicle body is turning, the yaw angular velocity output from the inertia measurement unit 108 is acquired from the CAN 111 (step 609), and the process proceeds to step 610. In step 610, the turning radius of the vehicle body is calculated. Here, calculation of the turning radius will be described with reference to FIG.

  FIG. 8 is a model of the vehicle body turning. As shown in this figure, when the steering angles of the left front wheel 101a and the right front wheel 101b are δl and δr, respectively, the distances (turning radii) Rl and Rr between the turning center 703 and the left and right front wheels 101a and 101b are as follows: (20)

  However, in the above equation (20), ω is the yaw angular velocity, and vl and vr are represented by the following equations (21) and (22), respectively. The left and right “front wheel rotation speeds” in the following formulas (21) and (22) are derived from the wheel speeds of the left and right front wheels 101 output from the front wheel speed detection unit 102 acquired via the CAN 111. Needless to say.

  Accordingly, when the tread 704 of the vehicle is T, the distance R (turning radius) between the intersection 705 of the front wheel tread shaft and the vehicle body shaft and the turning center is expressed by the following equation (23).

  When the turning radius R is calculated in step 610, the vehicle speed is calculated in step 611. The vehicle speed when the vehicle body is turning can be calculated by the following equation (24) based on the turning radius and the yaw angular velocity ω calculated in step 610. When the vehicle speed is calculated in step 611, the process proceeds to step 608.

  In step 608, the vehicle speed calculated in step 607 or 611 is output to the CAN 111, and the processing of the vehicle speed calculation unit 110 is terminated.

In the present embodiment configured as described above, the vehicle speed change detection unit 109 estimates time change (drive acceleration) of the vehicle speed based on the drive torque and the vehicle weight, and the vehicle speed calculation unit 110 based on the estimated value. Thus, the vehicle speed can be calculated with high accuracy without measuring the vehicle position. Therefore, accurate vehicle speeds can be calculated even in situations where it is difficult to measure the vehicle position using GPS, etc.In addition, the conventional technology that corrects errors based on changes in wheel radii includes changes in road surface conditions. However, according to the present embodiment, the vehicle speed can be accurately calculated without using the wheel radius. Yes. That is, the calculation accuracy of the vehicle speed when the construction vehicle including the dump truck travels off-road can be improved.

  In the above description, the case where the wheel speed correction coefficients of all the wheels (front wheels and rear wheels) are calculated (steps 209 and 210) has been described. However, as described above, the front wheel speed (driven wheel speed) is calculated. When the vehicle speed is calculated based on this, it is sufficient to calculate the wheel speed correction coefficient applied to the front wheel. In the above description, the vehicle speed is calculated based on the wheel speeds of the left and right front wheels. However, the vehicle speed may be calculated based on either the left or right wheel speed.

  Next, a modification of the above embodiment will be described. When there is no steering on a flat road with little change in road surface condition, the speed can be calculated by the following method.

  The front wheel speed detection unit 102 outputs the rotation speed of the front wheel (driven wheel) to the CAN 111, and the drive torque detection unit 106 outputs the drive wheel torque to the CAN 111. Further, the vehicle weight is output from the vehicle weight detection unit 107 to the CAN 111. Here, based on these pieces of information, the vehicle speed calculation unit 110 calculates the vehicle speed by the following method. FIG. 9 is a processing flow of the vehicle speed calculation unit 110 when there is no steering on a traveling road that is flat and has almost no change in road surface condition.

  As shown in FIG. 9, in step 801, the vehicle speed calculation unit 110 is periodically activated, and the process proceeds to step 802. In step 802, the vehicle weight output from the vehicle weight detector 107 and the average value of the left and right drive torques output from the drive torque detector 106 are acquired via the CAN 111, and the process proceeds to step 803. In step 803, drive acceleration is calculated from the drive torque and vehicle weight acquired in step 802 according to the following equation (25). In addition, the road surface resistance and air resistance in the following formula (25) are values set in advance by the vehicle.

  When step 803 is completed, the average value of the left and right front wheel speeds output from the front wheel speed detector 102 is acquired (step 804), and the process proceeds to step 805. In step 805, a wheel speed correction coefficient is calculated from the following equation (26) based on the driving acceleration calculated in step 803 and the average value of the front wheel speed acquired in step 804.

  When step 805 ends, the vehicle speed is calculated according to the following equation (27) (step 806).

  In step 807, the vehicle speed calculation unit 110 outputs the vehicle speed calculated in step 806 to the CAN 111, and ends the process.

  Even in the embodiment configured as described above, the temporal change (drive acceleration) of the vehicle speed is estimated based on the drive torque and the vehicle weight, and the vehicle speed is calculated based on the estimated value. The vehicle speed can be accurately calculated without measuring the vehicle position. Therefore, an accurate vehicle speed can be calculated even in a situation where it is difficult to measure the vehicle position using GPS or the like.

  In the above modification, in order to simplify the processing, the case where the vehicle speed is calculated by obtaining the average value of the front wheel speed has been described, but based on the left and right front wheel speeds as in the previous embodiment. Thus, the vehicle speed may be calculated.

  Next, a second embodiment of the present invention will be described. In the first embodiment and the modification thereof, the driving acceleration is estimated based on the “driving torque” output from the driving torque detection unit 106. However, in the present embodiment, “acceleration” is used instead of the driving torque. It is characterized in that the driving acceleration is estimated based on it.

  The hardware configuration of the system according to the present embodiment is the same as that shown in FIG. Further, here, in order to simplify the description, a case where the vehicle travels on a flat road that has almost no change in the road surface state will be described as an example. FIG. 10 is a processing flow of the vehicle speed calculation unit 110 according to the second embodiment, and is a case of a traveling road that is flat and hardly changes in road surface state.

  In the processing flow shown in FIG. 10, in step 901, the vehicle speed calculation unit 110 is activated at a regular cycle (activation cycle), and the process proceeds to step 902. In step 902, the vehicle longitudinal acceleration, vehicle body yaw rate, and vehicle body pitch rate output from the inertia measurement unit 108 are acquired via the CAN 111, and the process proceeds to step 903.

  In step 903, it is determined whether or not the vehicle is stopped. If it is determined that the vehicle is stopped, the initial vehicle body pitch angle is obtained by the following equation (28) based on the longitudinal acceleration output from the inertia measurement unit 108 in step 904, and the process is terminated. And wait for startup until the next cycle.

  On the other hand, if it is determined in step 903 that the vehicle has not stopped, the process proceeds to step 905, where the vehicle body pitch angle calculated one activation cycle before (one sample time before) and the vehicle body pitch acquired in step 902 are obtained. Based on the rate, the vehicle body pitch angle is calculated according to the following equation (29). If the “vehicle pitch angle before one start cycle” in the following equation (29) does not exist, the initial vehicle pitch angle calculated in step 904 is used.

  When step 905 is completed, drive acceleration is obtained based on the following equation in step 906. It should be noted that “longitudinal acceleration” and “vehicle body yaw rate” in the following formula are obtained in step 902, and “vehicle pitch angle” is calculated in step 905. The “distance between the rear wheel axle and the inertia measuring unit” in the following formula (30) is a value calculated from the dimensions of the inertia measuring unit 108 and the vehicle 1.

  After the drive acceleration is calculated in step 906, the same processing as in step 804 and subsequent steps in FIG. 9 is executed. That is, when step 906 is completed, the front wheel speed output from the front wheel speed detector 102 is acquired (step 804), and the process proceeds to step 805. In step 805, a wheel speed correction coefficient is calculated from the following equation (31) based on the driving acceleration calculated in step 906 and the average value of the left and right front wheel speeds acquired in step 804.

  When step 805 ends, the vehicle speed is calculated according to the following equation (32) (step 806).

  In step 807, the vehicle speed calculation unit 110 outputs the vehicle speed calculated in step 806 to the CAN 111, and ends the process.

  In the present embodiment configured as described above, the time change (drive acceleration) of the vehicle speed is estimated based on the longitudinal acceleration, and the vehicle speed is calculated based on the estimated value. The vehicle speed can be calculated with high accuracy without measurement. Therefore, an accurate vehicle speed can be calculated even in a situation where it is difficult to measure the vehicle position using GPS or the like.

  In the above embodiment, the case where the vehicle travels on a flat road that has almost no change in road surface state has been described as an example. However, as in the first embodiment, there is an inclination and the road surface state is not changed. Even when the vehicle travels on a traveling road having a change, the estimated value of the drive acceleration can be calculated by using the above formula in which the estimated value of the drive acceleration is calculated based on the longitudinal acceleration or the like. Therefore, also in this case, it is possible to calculate an accurate vehicle speed in a situation where it is difficult to measure the vehicle position by GPS or the like.

  Further, in the above embodiment, in order to simplify the processing, the case where the vehicle speed is calculated by obtaining the average value of the front wheel speed has been described, but the left and right front wheel speeds as in the first embodiment are described. The vehicle speed may be calculated based on the above.

  By the way, in each of the above-described embodiments, in order to avoid a decrease in vehicle speed calculation accuracy due to an increase in the slip ratio of the drive wheel (rear wheel 104) at the time of high load torque output, the speed of the driven wheel (front wheel 101) (wheel) However, the vehicle speed may be calculated based on the wheel speed of the driving wheel or the wheel speed of the driving wheel and the driven wheel. When the drive wheel is included, it is preferable to detect “slip”.

  The present invention is not limited to the above-described embodiments, and includes various modifications within the scope not departing from the gist thereof. For example, the present invention is not limited to the one having all the configurations described in the above embodiments, and includes a configuration in which a part of the configuration is deleted. In addition, part of the configuration according to one embodiment can be added to or replaced with the configuration according to another embodiment.

  In addition, each configuration related to the above-described control device, functions and execution processing of each configuration, etc. are realized by hardware (for example, logic for executing each function is designed by an integrated circuit). May be. Further, the configuration related to the control device may be a program (software) that realizes each function related to the configuration of the control device by being read and executed by an arithmetic processing device (for example, a CPU). Information related to the program can be stored in, for example, a semiconductor memory (flash memory, SSD, etc.), a magnetic storage device (hard disk drive, etc.), a recording medium (magnetic disk, optical disc, etc.), and the like.

  In the above description of each embodiment, the control line and the information line are shown to be understood as necessary for the description of the embodiment, but all the control lines and information lines related to the product are not necessarily included. It does not always indicate. In practice, it can be considered that almost all the components are connected to each other.

1 Construction vehicle (dump truck)
101 Front wheel (driven wheel)
102 Front wheel speed detection unit 103 Steering angle detection unit 104 Rear wheel (drive wheel)
105 Rear Wheel Wheel Speed Detection Unit 106 Drive Torque Detection Unit 107 Vehicle Weight Detection Unit 108 Inertial Measurement Unit 109 Vehicle Speed Change Detection Unit 110 Vehicle Speed Calculation Unit 111 CAN
112 Memory (storage device)

Claims (4)

In construction vehicles with multiple wheels,
An acceleration sensor for detecting at least a longitudinal acceleration of the construction vehicle;
An angular velocity sensor for detecting at least the pitch angular velocity and the yaw angular velocity of the construction vehicle;
A speed change detection unit that calculates an estimated value of a time change of the vehicle speed of the construction vehicle based on the longitudinal acceleration, the pitch angular velocity, and the yaw angular velocity;
Based on the estimated value of the time change of the vehicle speed and the time change of the wheel speed of at least one of the plurality of wheels, a speed correction coefficient of the at least one wheel speed is calculated, and the at least one wheel A construction vehicle comprising: a speed calculation unit that calculates the vehicle speed by correcting a speed with the speed correction coefficient . The construction vehicle according to claim 1 ,
The construction vehicle , wherein the speed calculation unit calculates a speed correction coefficient for the at least one wheel speed in consideration of a load applied to the at least one wheel and a road surface friction coefficient. The construction vehicle according to claim 2 ,
The construction vehicle characterized in that the speed calculation unit calculates the vehicle speed in consideration of a turning radius of the construction vehicle and the yaw angular velocity. The construction vehicle according to claim 1,
The construction vehicle characterized in that the at least one wheel speed used when the speed calculation unit calculates the vehicle speed is that of a driven wheel.

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