Brake control device for industrial vehicles

Abstract

The braking control device (100) of the industrial vehicle according to the present invention includes: a map information acquisition unit (11); a position information acquisition unit (12); a travel information acquisition unit (13); an automatic driving control unit (14) that performs automatic driving control including calculating the required deceleration of the industrial vehicle; and a braking force control unit (15) that controls the braking unit in a manner capable of changing the distribution of the regenerative braking force and the mechanical braking force. The braking force control unit (15) controls the braking unit with a first distribution in which the distribution ratio of the mechanical braking force is larger than a second distribution when neither the first condition that a predetermined first time has elapsed after the industrial vehicle starts going downhill nor the second condition that the industrial vehicle is going downhill on a downhill road with a predetermined gradient or more is satisfied during the automatic driving of the industrial vehicle.

Description

Technical Field

[0001] The present invention relates to a braking control device for an industrial vehicle. Background Art

[0002] In recent years, attempts have been made to configure industrial vehicles such as tractors or forklifts as electric vehicles capable of, for example, autonomous driving within a limited area. Such an industrial vehicle includes a traveling motor that generates regenerative braking force and a mechanical brake that generates mechanical braking force as a braking unit, and can perform braking, for example, by regeneration achieved by the traveling motor during autonomous driving downhill.

[0003] Incidentally, as a braking control device for an industrial vehicle, for example, the technique described in Patent Document 1 is known. The braking control device for an industrial vehicle described in Patent Document 1 controls an inverter control device based on the terminal voltage of a battery charged by the regenerative power of a traveling motor to limit the regenerative torque command value of the traveling motor.

[0004] Background Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Laid-Open No. 2012-200048 Summary of the Invention

[0007] [Problems to be Solved by the Invention]

[0008] Incidentally, in an industrial vehicle that is configured as an electric vehicle capable of autonomous driving as described above, due to the influence of a downhill road, it may not be possible to obtain regenerative braking force in order to protect the battery when the battery is fully charged. However, a travel plan is not necessarily generated in advance considering the influence of a downhill road existing on the autonomous driving route. Therefore, when the industrial vehicle autonomously drives along a travel route with a downhill road in a state where the battery is fully charged, it may not be possible to obtain regenerative braking force and the required braking force may not be achieved. On the other hand, if the charging amount of the battery is restricted in advance in order to enable charging by regeneration, the operation time of the industrial vehicle may be shortened.

[0009] An object of the present invention is to provide a braking control device for an industrial vehicle that can appropriately brake even when driving downhill in a state where the battery is fully charged without having to generate a travel plan in advance considering the influence of a downhill road existing on the autonomous driving route.

[0010] [Technical Means for Solving the Problems]

[0011] A braking control device for an industrial vehicle according to an aspect of the present invention includes a traveling motor that generates a regenerative braking force and a mechanical brake that generates a mechanical braking force as a braking unit, charges a battery using the regenerative braking force, and includes: a map information acquisition unit that acquires map information; a position information acquisition unit that acquires the position information of the industrial vehicle; a traveling information acquisition unit that acquires the traveling information of the industrial vehicle; an autonomous driving control unit that executes autonomous driving control including calculating a required deceleration of the industrial vehicle based on the map information, the position information, and the traveling information; and a braking force control unit that controls the braking unit in such a manner that the distribution of the regenerative braking force and the mechanical braking force can be changed based on the required deceleration; the braking force control unit determines whether a first condition that a predetermined first time has elapsed since the start of downhill travel of the industrial vehicle or a second condition that the industrial vehicle is traveling downhill on a downhill road with a predetermined gradient or more is satisfied based on the map information and the position information, and during the autonomous driving of the industrial vehicle, when the first condition or the second condition is satisfied, controls the braking unit with a first distribution in which the distribution ratio of the mechanical braking force is larger than a second distribution when neither the first condition nor the second condition is satisfied.

[0012] In the braking control device for an industrial vehicle according to an aspect of the present invention, the braking unit is controlled by the braking force control unit. In the control of the braking unit, the distribution of the regenerative braking force and the mechanical braking force can be changed based on the required deceleration. The braking force control unit determines whether a first condition that a predetermined first time has elapsed since the start of downhill travel of the industrial vehicle or a second condition that the industrial vehicle is traveling downhill on a downhill road with a predetermined gradient or more is satisfied based on the position information and the map information. By this determination of the first condition or the second condition, it is possible to determine that the industrial vehicle is traveling downhill even in autonomous driving where the traveling route is not determined in advance. Further, when the first condition or the second condition is satisfied during the autonomous driving of the industrial vehicle, the braking unit is controlled with a first distribution in which the distribution ratio of the mechanical braking force is larger than a second distribution when neither the first condition nor the second condition is satisfied during the autonomous driving of the industrial vehicle. As a result, the regenerative current is suppressed in the industrial vehicle traveling downhill, and thus, it is not necessary to limit the charging amount in advance assuming, for example, that it will pass through a downhill road. Therefore, according to this braking control device for an industrial vehicle, it is not necessary to generate a travel plan in advance considering the influence of a downhill road existing on the autonomous driving route, and even when traveling downhill in a state where the battery is fully charged, appropriate braking can be performed.

[0013] In one embodiment, the braking force control unit may also determine whether a predetermined second time has elapsed after the first condition is satisfied, or whether a release condition that the downhill has ended after the second condition is satisfied is satisfied, and when the release condition is satisfied during the period of controlling the braking unit with the first distribution, end the control of the braking unit with the first distribution. In this case, it is possible to end the control of the braking unit with the first distribution based on a predetermined time after the first condition is satisfied or the gradient after the second condition is satisfied.

[0014] In one embodiment, the braking force control unit may also determine whether the first condition or the second condition is satisfied based on the regenerative current of the traveling motor. In this case, it is possible to determine whether the first condition or the second condition is satisfied by determining that the industrial vehicle is going downhill when the regenerative current of the traveling motor reaches a predetermined current threshold or more, for example.

[0015] [Advantages of the Invention]

[0016] According to the present invention, it is not necessary to generate a travel plan in advance considering the influence of a downhill road existing on the travel route of the autonomous driving, and even when traveling along a downhill road in a state where the battery is fully charged, braking can be appropriately performed. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic configuration diagram of an industrial vehicle to which a braking control device according to one embodiment is applied.

[0018] Figure 2 represents Figure 1 a block diagram of the functional configuration of the braking control device of the industrial vehicle.

[0019] Figure 3 represents Figure 1 an operation example diagram of the braking control device of the industrial vehicle.

[0020] Figure 4 represents Figure 1 a flowchart of a processing example of the braking control device of the industrial vehicle. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or equivalent elements are denoted by the same reference numerals, and repeated description is omitted.

[0022] Figure 1 is a schematic configuration diagram of an industrial vehicle to which a braking control device according to one embodiment is applied. Figure 1 The industrial vehicle 1 shown is, for example, an electric tow tractor and is used to tow a container loaded with goods at an airport, in a factory, at a port, or the like.

[0023] The industrial vehicle 1 is configured to be able to execute autonomous driving control. Autonomous driving refers to, for example, a driving state in which vehicle control is performed to automatically drive the industrial vehicle 1 in accordance with a conveyance command from an operation management system or the like. The operation management system is a so-called control system that performs conveyance command, operation monitoring, and vehicle state monitoring of the industrial vehicle 1. In autonomous driving, the operator does not need to perform a driving operation, and the vehicle automatically travels.

[0024] The autonomous driving here is implemented in a specified area including, for example, runways, takeoff and landing areas, taxiways, aprons, control towers, hangars, cargo handling areas, charging areas, etc. in an airport. The industrial vehicle 1 can perform autonomous driving without a pre-determined driving route in the specified area, or autonomous driving that generates a driving plan without considering the influence of downhill roads existing on the driving route even though the driving route is pre-determined.

[0025] [Constitution related to the driving and braking of the industrial vehicle 1]

[0026] The industrial vehicle 1 is equipped with FL tires 2 and FR tires 3 arranged at the front of the vehicle body, and RL tires 4 and RR tires 5 arranged at the rear of the vehicle body. The industrial vehicle 1 is equipped with a left driving motor 6 that drives the RL tire 4 and a right driving motor 7 that drives the RR tire 5 as driving motors. The driving motors also function as a braking unit 8 that generates regenerative braking force.

[0027] The left driving motor 6 and the right driving motor 7 are AC motors that also function as generators. A left drive unit 6a serving as a speed reducer is interposed between the left driving motor 6 and the RL tire 4. A right drive unit 7a serving as a speed reducer is interposed between the right driving motor 7 and the RR tire 5.

[0028] The left driving motor 6 is electrically connected to the contactor 9 via the left motor driver 6b. The right driving motor 7 is electrically connected to the contactor 9 via the right motor driver 7b. The left motor driver 6b and the right motor driver 7b each have, for example, an inverter and are electrically connected to the controller 10. Through the left motor driver 6b and the right motor driver 7b, the power operation and regeneration of the left driving motor 6 and the right driving motor 7 are controlled by the controller 10. In addition, the left motor driver 6b and the right motor driver 7b can also detect the regenerative current of the left driving motor 6 and the right driving motor 7 respectively.

[0029] The contactor 9 is electrically connected to the battery B. In addition, the contactor 9 is electrically connected to the controller 10. Through the contactor 9, the power supply of the battery B including emergency stop is controlled by the controller 10.

[0030] The battery B is a power supply source for the left driving motor 6 and the right driving motor 7. The battery B includes, for example, a lead-acid battery and is a storage battery capable of storing the regenerative power generated by the regenerative braking of the left driving motor 6 and the right driving motor 7.

[0031] When the left traveling motor 6 is rotationally driven, the driving force of the left traveling motor 6 is transmitted to the RL tire 4 via the left drive unit 6a, so that the RL tire 4 rotates. In addition, the left traveling motor 6 also functions as a generator. Specifically, when the industrial vehicle 1 brakes, the left traveling motor 6 operates as a generator by the rotation of the RL tire 4. That is to say, the regenerative braking of the left traveling motor 6 is performed, the left traveling motor 6 generates regenerative power, and at the same time, the RL tire 4 is braked by the regenerative braking force.

[0032] When the right traveling motor 7 is rotationally driven, the driving force of the right traveling motor 7 is transmitted to the RR tire 5 via the right drive unit 7a, so that the RR tire 5 rotates. In addition, the right traveling motor 7 also functions as a generator. Specifically, when the industrial vehicle 1 brakes, the right traveling motor 7 operates as a generator by the rotation of the RR tire 5. That is to say, the regenerative braking of the right traveling motor 7 is performed, the right traveling motor 7 generates regenerative power, and at the same time, the RR tire 5 is braked by the regenerative braking force.

[0033] The industrial vehicle 1 includes FL disc brakes 8a and FR disc brakes 8b as mechanical brakes in the brake unit 8, and they are arranged at the front part of the vehicle body and installed in a manner capable of braking the FL tire 2 and the FR tire 3 respectively. The industrial vehicle 1 includes RL drum brakes 8c and RR drum brakes 8d, and they are arranged at the rear part of the vehicle body and installed in a manner capable of braking the RL tire 4 and the RR tire 5 respectively.

[0034] The industrial vehicle 1 includes a brake pedal 30, a master cylinder 31, and an ESC (Electronic Stability Control system) unit 32. The brake pedal 30 is for an operator to step on during driving (manual driving) of the operator.

[0035] The master cylinder 31 generates oil pressure according to the stepping operation of the operator. The master cylinder 31 is connected to the ESC unit 32 through an oil pressure circuit. The ESC unit 32 is, for example, an oil pressure control unit in which a processor, a motor, a pump, and a valve are integrated. The processor is, for example, an arithmetic unit such as a CPU [Central Processing Unit]. The processor generally controls, for example, a ROM [ReadOnly Memory], a RAM [Random Access Memory], and a communication interface.

[0036] The ESC unit 32 is electrically connected to the controller 10. An oil pressure sensor is built in the ESC unit 32, and the oil pressure information detected by the oil pressure sensor is sent to the controller 10. The ESC unit 32 is controlled by the controller 10, for example, according to a control signal based on the oil pressure information.

[0037] The ESC unit 32 is connected to the FL disc brake 8a and the FR disc brake 8b through a hydraulic pressure circuit 33 for front-wheel braking. The ESC unit 32 is connected to the RL drum brake 8c and the RR drum brake 8d through a hydraulic pressure circuit 34 for rear-wheel braking.

[0038] When the operator depresses the brake pedal 30, a piston disposed within the cylinder of the master cylinder 31 is pushed, whereby hydraulic oil flows out from the master cylinder 31 to the ESC unit 32. The hydraulic oil flowing into the ESC unit 32 is independently supplied to each of the hydraulic pressure circuit 33 and the hydraulic pressure circuit 34. Thereby, hydraulic oil is supplied to the FL disc brake 8a and the FR disc brake 8b, and the FL disc brake 8a and the FR disc brake 8b are actuated, and the FL tire 2 and the FR tire 3 are braked by mechanical braking force. In addition, independent of the braking of the front wheels, hydraulic oil is supplied to the RL drum brake 8c and the RR drum brake 8d, the RL drum brake 8c and the RR drum brake 8d are actuated, and the RL tire 4 and the RR tire 5 are braked by mechanical braking force.

[0039] The industrial vehicle 1 is provided with a left electromagnetic brake 6c and a right electromagnetic brake 7c, which are mounted in a manner capable of braking the left traveling motor 6 and the right traveling motor 7, respectively. The left electromagnetic brake 6c and the right electromagnetic brake 7c are electrically connected to the controller 10 and are used as parking brakes when the industrial vehicle 1 stops.

[0040] [Configuration related to the automatic driving control and braking control of the industrial vehicle 1]

[0041] Figure 2 is a block diagram showing Figure 1 the functional configuration of a braking control device for an industrial vehicle. The braking control device 100 of the industrial vehicle has a controller 10 that comprehensively performs braking control and automatic driving control of the industrial vehicle 1. The controller 10 is an electronic control unit having a CPU, a ROM, a RAM, etc. In the controller 10, for example, various functions are realized by loading a program recorded in the ROM into the RAM and executing the program loaded into the RAM by the CPU. The controller 10 can also detect the voltage of the battery B. In addition, the controller 10 may include a plurality of electronic units.

[0042] The controller 10 is connected to a GNSS (Global Navigation Satellite System) receiver 21, a surrounding situation sensor 22, a traveling information sensor 23, and a map database 24.

[0043] The GNSS receiver 21 determines the position of the industrial vehicle 1 on the map (e.g., the latitude and longitude of the industrial vehicle 1) by receiving signals from three or more GNSS satellites. The GNSS receiver 21 transmits the measured position information of the industrial vehicle 1 to the controller 10.

[0044] The surrounding situation sensor 22 is an in-vehicle detector that detects the situation around the vehicle. The surrounding situation sensor 22 includes a camera and a lidar [LiDAR: Light Detection And Ranging]. The captured information of the camera is used, for example, for road surface pattern recognition and matching. The obstacle information detected by the lidar is used, for example, for the industrial vehicle 1 to avoid danger. The surrounding situation sensor 22 transmits information related to the surrounding situation of the industrial vehicle 1 to the controller 10.

[0045] The driving information sensor 23 is a detector that detects the driving state of the industrial vehicle 1. The driving information sensor 23 includes a vehicle speed sensor, an acceleration sensor, and a yaw rate sensor (gyro sensor). The vehicle speed sensor is a detector that detects the speed of the industrial vehicle 1. As the vehicle speed sensor, for example, a speed sensor can be used, which is respectively provided on the left driving motor 6 and the right driving motor 7 to detect the rotational speed of the left driving motor 6 and the rotational speed of the right driving motor 7. The driving information sensor 23 transmits the detected driving information to the controller 10.

[0046] The map database 24 is a database that stores map information. The map database 24 is formed, for example, in a storage device (e.g., HDD [Hard Disk Drive, hard disk drive], etc.) mounted on the industrial vehicle 1. The map information includes the position information of roads, road shape information (e.g., types of curves, straight sections, curvature of curves, slopes of roads, etc.), position information of intersections and branch points, and position information of structures, etc., as information on a specified area including, for example, runways, takeoff and landing areas, taxiways, apron areas, towers, hangars, cargo handling areas, charging areas, etc. in an airport. The map information includes the position information of the road surface pattern for position recognition of the industrial vehicle 1. In addition, the map database 24 can also be formed in a server that can communicate with the industrial vehicle 1.

[0047] Next, the functional configuration of the controller 10 will be described. The controller 10 has a map information acquisition unit 11, a position information acquisition unit 12, a driving information acquisition unit 13, an autonomous driving control unit 14, and a braking force control unit 15. In addition, a part of the functions of the controller 10 described below can also be implemented in a server that can communicate with the vehicle.

[0048] The map information acquisition unit 11 acquires the map information stored in the map database 24. The map information acquisition unit 11 acquires at least the position information of the road surface pattern for position recognition of the industrial vehicle 1 and the gradient information of the road.

[0049] The position information acquisition unit 12 acquires the position information of the industrial vehicle 1 based on the reception result of the GNSS receiver 21, the detection result of the surrounding situation sensor 22, and the map information of the map database 24. The position information acquisition unit 12 acquires the position of the industrial vehicle 1 itself based on the position information of the road surface pattern included in the map information and the relative position information of the road surface pattern detected by the surrounding situation sensor 22 with respect to the industrial vehicle 1. In addition, the position information acquisition unit 12 may also use, for example, the SLAM [Simultaneous Localization And Mapping] method to infer the position of the industrial vehicle 1 itself.

[0050] The travel information acquisition unit 13 acquires the travel information of the industrial vehicle 1 based on the detection result of the travel information sensor 23. Here, the travel information acquisition unit 13 acquires the vehicle speed of the industrial vehicle 1 based on the detection results of the speed sensors respectively provided on the left travel motor 6 and the right travel motor 7. The travel information acquisition unit 13 may also acquire the direction of the industrial vehicle 1 based on the detection result of the gyro sensor.

[0051] The automatic driving control unit 14 performs automatic driving control including calculating the required deceleration of the industrial vehicle 1 based on the position information, travel information, and map information. The automatic driving control unit 14 generates a travel plan along the target route based on the position information of the industrial vehicle 1 measured by the GNSS receiver 21, the map information of the map database 24, the surrounding situation of the industrial vehicle 1 (such as the position of obstacles) identified according to the detection result of the surrounding situation sensor 22, and the travel state (vehicle speed, yaw rate, etc.) identified according to the detection result of the travel information sensor 23. The target route is set according to the conveyance command of the operation management system.

[0052] The automatic driving control unit 14 performs automatic driving according to the travel plan. The travel plan includes, for example, the target speed, required acceleration, and required deceleration. Here, the automatic driving control unit 14 performs automatic driving control and braking control by sending control signals to the left drive unit 6a, the right drive unit 7a, and the ESC unit 32 to achieve the target speed, required acceleration, and required deceleration.

[0053] As an example, the autonomous driving control unit 14 sets a target speed based on the position of the industrial vehicle 1. For example, when the industrial vehicle 1 is going downhill on a downhill road, the autonomous driving control unit 14 sets the target speed to a specified fixed speed (e.g., 15 km / h, etc.), and calculates a deceleration of 0 as the required deceleration for maintaining the vehicle speed of the industrial vehicle 1 at the target speed. In this case, for example, if the slope of the downhill road is fixed, the required braking force is calculated as a substantially fixed braking force. The required braking force refers to the braking force required to achieve the required deceleration.

[0054] The braking force control unit 15 controls the braking unit 8 in such a way that it can change the distribution of the regenerative braking force and the mechanical braking force based on the required deceleration. The braking force control unit 15 changes the distribution of the regenerative braking force and the mechanical braking force based on the position information of the industrial vehicle 1 and the map information of the map database 24.

[0055] In the present embodiment, the change in the distribution of the regenerative braking force and the mechanical braking force means that the regenerative braking force changes as the mechanical braking force changes. Specifically, the braking force control unit 15 calculates the regenerative braking force based on the change rate of the rotational speed of each of the left traveling motor 6 and the right traveling motor 7 detected by the speed sensor. The braking force control unit 15 calculates a target rotational speed for generating the required deceleration (negative acceleration of the industrial vehicle 1), and calculates the regenerative braking force in such a way that the detected change rate of the rotational speed becomes the target rotational speed (e.g., reducing the rotational speed by a specified amount after a specified second, etc.). Therefore, when both the mechanical braking force and the regenerative braking force are present, the target rotational speed corresponding to the deceleration obtained by calculating and subtracting the deceleration amount generated by the mechanical braking force is calculated. Therefore, the greater the distribution of the mechanical braking force, the smaller the distribution of the regenerative braking force, and the smaller the distribution of the mechanical braking force, the greater the distribution of the regenerative braking force.

[0056] The braking force control unit 15 determines whether the first condition that a specified first time has elapsed since the industrial vehicle 1 started going downhill or the second condition that the industrial vehicle 1 is going downhill on a downhill road with a slope of a specified degree or more is satisfied, based on, for example, the position information of the industrial vehicle 1 and the slope information of the road on which the industrial vehicle 1 is traveling. The first condition and the second condition are conditions for determining whether to change the distribution of the regenerative braking force and the mechanical braking force. Since the first condition and the second condition are determined in real time based on the slope information of the road on which the industrial vehicle 1 is traveling, it can also be considered as conditions for suppressing regenerative braking when generating a travel plan in advance without considering the influence of the downhill road existing on the travel route of the autonomous driving.

[0057] The specified first time corresponds to a confirmation time for confirming that the industrial vehicle 1 continues to go downhill after starting to go downhill. The first time can be, for example, a constant value of about several seconds, or the shorter the greater the downhill slope.

[0058] The specified slope is the slope value equivalent to the case where the regenerative current increases to a level above a fixed value during the downhill travel of the industrial vehicle 1. The specified slope is compared with the slope information obtained based on the map database 24. The specified slope can be, for example, a constant value, which is the magnitude of the downhill slope equivalent to a specified regenerative current value, or it can be set to a slope value that becomes smaller as the battery B gets closer to being fully charged.

[0059] In addition, the braking force control unit 15 can also determine whether the first condition or the second condition is satisfied based on the regenerative currents of the left traveling motor 6 and the right traveling motor 7. For example, instead of the method of comparing the specified slope with the slope information, it can be determined whether the regenerative current increases to a level above a fixed value during the downhill travel of the industrial vehicle 1 based on the regenerative currents detected by the left motor driver 6b and the right motor driver 7b (the regenerative currents generated by the regenerative braking of the following second distribution R2).

[0060] When neither the first condition nor the second condition is satisfied, for example, when the industrial vehicle 1 is traveling on flat ground, etc., the braking force control unit 15 controls the braking unit 8 by setting the distribution of the regenerative braking force and the mechanical braking force to the second distribution. The second distribution is the general braking force distribution used when the industrial vehicle 1 is traveling on flat ground or when the industrial vehicle 1 is traveling on a downhill road with a slope smaller than the specified slope. The second distribution can be, for example, a distribution such that the mechanical braking force is smaller than the regenerative braking force (refer to Figure 3 (a) symbol R2).

[0061] Figure 3 It represents Figure 1 the operation example diagram of the braking control device of the industrial vehicle. As Figure 3 shown, from time t0 to time t1, for example, it is the case where the industrial vehicle 1 is traveling on flat ground, etc., and neither the first condition nor the second condition is satisfied. In this case, the braking force control unit 15 controls the braking unit 8 with the second distribution R2. In addition, in Figure 3 the example, it is assumed that the slope of the downhill road is fixed, the target vehicle speed is fixed, and the required braking force Breq is fixed, but the required braking force can also change with time.

[0062] For example, when the first condition or the second condition is satisfied during the automatic driving of the industrial vehicle 1, the braking force control unit 15 controls the braking unit 8 with the first distribution R1 in which the distribution ratio of the mechanical braking force is larger than the second distribution R2. The first distribution R1 is the braking force distribution used when the industrial vehicle 1 is traveling on a downhill road where regenerative braking should be suppressed. The first distribution R1 can be, for example, a distribution such that the mechanical braking force is larger than the regenerative braking force, or it can be a distribution such that the regenerative braking force is canceled and only the mechanical braking force is set (refer to Figure 3 (a) symbol R1).

[0063] In Figure 3In the example, the braking force control unit 15 determines that the first condition or the second condition is satisfied at time t1. The battery voltage V1 at time t1 is equal to or lower than the battery voltage VL in the fully charged state. That is to say, the first condition or the second condition can be set as a condition that is determined to be sufficient by the braking force control unit 15 before the battery voltage exceeds the battery voltage VL. The battery voltage VL in the fully charged state is equivalent to the upper limit battery voltage such that if charging continues, the battery B will be in an overcharged state and deteriorate. Therefore, by controlling the brake unit 8 with the first distribution R1, it is possible to suppress the voltage of the battery B from reaching the battery voltage VL, thereby avoiding situations such as interrupting the regenerative braking when the voltage of the battery B reaches the battery voltage VL during the regenerative braking process to protect the battery B, for example.

[0064] The braking force control unit 15 determines whether a specified second time has elapsed after the first condition is satisfied, or whether a release condition that the downhill has ended after the second condition is satisfied is met. When the release condition is met during the period of controlling the brake unit 8 with the first distribution R1, the control of the brake unit 8 with the first distribution R1 ends. The release condition is a condition for determining whether to restore the distribution of the mechanical braking force increased to suppress the regenerative braking force to its original state.

[0065] The specified second time is equivalent to the time when it is expected that the downhill should have ended based on the situation that a fixed time has elapsed since the industrial vehicle 1 started going downhill. The second time is a time longer than the first time and can be, for example, a constant value of about 10 seconds.

[0066] That the downhill has ended after the second condition is satisfied means, for example, that based on the slope information obtained from the map database 24, the slope information after the second condition is satisfied is less than the specified slope. In addition, instead of the method of comparing the specified slope with the slope information, when determining the second condition based on the regenerative current detected by the left motor driver 6b and the right motor driver 7b, the regenerative current is also suppressed by setting the first distribution R1. Therefore, it is also possible to determine that the downhill has ended by the method based on the slope information obtained from the map database 24.

[0067] In Figure 3 the example, the braking force control unit 15 determines that the release condition is satisfied at time t3. The battery voltage at time t3 is the battery voltage V2 that is less than the battery voltage V1. The braking force control unit 15 determines that the release condition is satisfied at time t3, ends the control of the brake unit 8 with the first distribution R1, and changes the distribution to, for example, controlling the brake unit 8 with the second distribution R2.

[0068] In addition, when changing the distribution of the regenerative braking force and the mechanical braking force, the braking force control unit 15 can, like Figure 3 from time t1 to time t2 inFigure 3 From time t3 to time t4 in [the above], the distribution of the mechanical braking force is continuously reduced from the distribution R1 before the change to the distribution R2 after the change. Thus, the regenerative braking force of the braking unit 8 easily follows the change in the mechanical braking force. Therefore, compared with the case where the distribution is changed abruptly, stabilization of the braking force generated by the entire braking unit 8 can be achieved.

[0069] [An example of the arithmetic processing executed by the controller 10]

[0070] Next, an example of the arithmetic processing executed by the controller 10 will be described. Figure 4 represents Figure 1 a flowchart of a processing example of a braking control device for an industrial vehicle. Figure 4 The processing example shown is executed, for example, during the autonomous driving of the industrial vehicle 1.

[0071] As Figure 4 shown, in S01, the controller 10 acquires the position information of the industrial vehicle 1 through the position information acquisition unit 12. The position information acquisition unit 12 acquires the position information of the industrial vehicle 1, for example, based on the reception result of the GNSS receiver 21, the detection result of the surrounding situation sensor 22, and the map information of the map database 24.

[0072] In S02, the controller 10 acquires the driving information of the industrial vehicle 1 through the driving information acquisition unit 13. The driving information acquisition unit 13 acquires the driving information of the industrial vehicle 1, for example, based on the detection result of the driving information sensor 23.

[0073] In S03, the controller 10 acquires the slope information of the road on which the industrial vehicle 1 is traveling through the braking force control unit 15. The braking force control unit 15 acquires the slope information of the road on which the industrial vehicle 1 is traveling, for example, based on the position information acquired by the position information acquisition unit 12 and the slope information included in the map information of the map database 24. In addition, the braking force control unit 15 may also acquire the slope information of the road on which the industrial vehicle 1 is traveling based on the regenerative current of the left traveling motor 6 and the right traveling motor 7 (the regenerative current generated by the regenerative braking with the second distribution R2). The acquired slope information is used to determine whether the first condition or the second condition is satisfied.

[0074] In S04, the controller 10 acquires the driving plan of the industrial vehicle 1 through the autonomous driving control unit 14. The autonomous driving control unit 14 acquires the driving plan of the industrial vehicle 1, for example, based on the position information acquired by the position information acquisition unit 12 and the driving information acquired by the driving information acquisition unit 13. The autonomous driving control unit 14 may also acquire the driving plan generated by an operation management system capable of communicating with the industrial vehicle 1 as a conveyance command.

[0075] In S05, the controller 10 obtains the required deceleration of the industrial vehicle 1 through the automatic driving control unit 14. The automatic driving control unit 14 obtains the required deceleration of the industrial vehicle 1 based on, for example, the driving information obtained by the driving information acquisition unit 13 and the driving plan obtained by the automatic driving control unit 14.

[0076] In S06, the controller 10 determines whether the first condition is satisfied through the braking force control unit 15. The braking force control unit 15 determines whether the first condition that the industrial vehicle 1 has passed a specified first time after starting to go downhill is satisfied based on, for example, the position information and the map information.

[0077] When the braking force control unit 15 determines in S06 that the first condition is not satisfied, in S07, the controller 10 determines whether the second condition is satisfied through the braking force control unit 15. The braking force control unit 15 determines whether the second condition that the industrial vehicle 1 is going downhill on a downhill road with a specified gradient or more is satisfied based on, for example, the position information and the map information.

[0078] When the braking force control unit 15 determines in S07 that the second condition is not satisfied, in S08, the controller 10 controls the braking unit 8 by the second distribution through the braking force control unit 15. The braking force control unit 15 controls the braking unit 8 by the second distribution, for example. Then, the controller 10 ends Figure 4 the process.

[0079] On the other hand, when the braking force control unit 15 determines in S06 that the first condition is satisfied, or when the braking force control unit 15 determines in S07 that the second condition is satisfied, in S09, the controller 10 determines whether the release condition is not satisfied through the braking force control unit 15. The braking force control unit 15 determines whether, for example, a specified second time has passed after the first condition is satisfied, or whether the release condition that the downhill has ended after the second condition is satisfied is satisfied.

[0080] When the braking force control unit 15 determines in S09 that the release condition is not not satisfied (the release condition is satisfied), the controller 10 performs the process of S08. For example, when the release condition is satisfied during the control of the braking unit 8 by the first distribution, the braking force control unit 15 ends the control of the braking unit 8 by the first distribution and controls the braking unit 8 by the second distribution.

[0081] When the braking force control unit 15 determines in S09 that the release condition is not satisfied (the release condition is not satisfied), the controller 10 performs the process of S10. The braking force control unit 15 controls the braking unit 8 by the first distribution, which is larger than the second distribution when neither the first condition nor the second condition is satisfied, for example, with the distribution ratio of the mechanical braking force. Then, the controller 10 ends Figure 4 the process.

[0082] [Function and Effect]

[0083] As described above, in the braking control device 100 of the industrial vehicle according to the present embodiment, the braking unit 8 is controlled by the braking force control unit 15. In the control of the braking unit 8, the distribution of the regenerative braking force and the mechanical braking force can be changed based on the required deceleration. The braking force control unit 15 determines whether the first condition that a predetermined first time has elapsed since the industrial vehicle 1 started going downhill or the second condition that the industrial vehicle 1 is going downhill on a downhill road with a predetermined gradient or more is satisfied based on the position information and the map information. By determining the first condition or the second condition in this way, even in the case of autonomous driving where the driving route is not determined in advance, it can be determined that the industrial vehicle 1 is going downhill. Further, when the first condition or the second condition is satisfied during the autonomous driving of the industrial vehicle 1, the braking unit 8 is controlled with the first distribution in which the distribution ratio of the mechanical braking force is larger than the second distribution when neither the first condition nor the second condition is satisfied during the autonomous driving of the industrial vehicle 1. As a result, the regenerative current is suppressed in the industrial vehicle 1 that is going downhill. Therefore, it is not necessary to limit the charge amount (charge rate SOC) in advance assuming, for example, that it will pass through a downhill road. Therefore, according to the braking control device 100 of the industrial vehicle, it is not necessary to generate a driving plan in advance considering the influence of the downhill road existing on the driving route of the autonomous driving, and even when driving downhill in a state where the battery is fully charged, it is possible to brake appropriately.

[0084] In addition, for example, it is possible to suppress the occurrence of a situation (so-called regenerative loss) in which when decelerating mainly with the regenerative braking force, the battery B reaches the fully charged state and the regenerative braking cannot be used, resulting in insufficient braking force. Further, in the industrial vehicle 1, even on a downhill road with the same downhill gradient, the range of values that the required braking force can take is wide depending on the weight of the towed or loaded goods. However, according to the braking control device 100 of the industrial vehicle, the braking unit 8 is controlled in such a way that the required braking force is used as the total braking force and the distribution of the mechanical braking force is increased. Therefore, it is possible to brake appropriately according to the weight of the goods.

[0085] In the braking control device 100 of the industrial vehicle, the braking force control unit 15 determines whether a predetermined second time has elapsed after the first condition is satisfied, or whether the release condition that the downhill has ended after the second condition is satisfied is satisfied. When the release condition is satisfied during the period of controlling the braking unit 8 with the first distribution, the control of the braking unit 8 with the first distribution is ended. As a result, it is possible to end the control of the braking unit 8 with the first distribution based on the predetermined time after the first condition is satisfied or the gradient after the second condition is satisfied.

[0086] In the braking control device 100 of the industrial vehicle, the braking force control unit 15 determines whether the first condition or the second condition is satisfied based on the regenerative current of the left traveling motor 6 and the right traveling motor 7. As a result, by determining that the industrial vehicle 1 is going downhill when the regenerative current of, for example, the left traveling motor 6 and the right traveling motor 7 reaches a predetermined current threshold or more, it is possible to determine whether the first condition or the second condition is satisfied.

[0087] [Variant Example]

[0088] The embodiments of the present invention have been described above, but the present invention is not limited to the described embodiments.

[0089] In the above-described embodiments, an electric tow tractor such as Figure 1 is illustrated as the industrial vehicle 1, but it is not limited thereto. The industrial vehicle 1 can be, for example, an electric forklift or a hybrid industrial vehicle. In short, any industrial vehicle can be used as long as it can charge the battery B through regenerative braking, has a traveling motor that generates regenerative braking force and a mechanical brake that generates mechanical braking force as a braking unit, and can change the distribution of the regenerative braking force and the mechanical braking force based on the required deceleration.

[0090] In addition, as a system of the mechanical brake that generates mechanical braking force, a configuration using the ESC unit 32 is illustrated, but other hydraulic control devices can also be used. As the mechanical brake, it is not limited to a disc brake and a drum brake using hydraulic pressure, and the braking forces of the left electromagnetic brake 6c and the right electromagnetic brake 7c can also be regarded as mechanical braking forces.

[0091] The configuration for the automatic driving of the industrial vehicle 1 is not limited to the examples of the above-described embodiments. For example, a lidar is used in the surrounding situation sensor 22, but it can be replaced with other sensors. In addition, the map information in the map database 24 includes slope information, but when using the regenerative current to determine the first condition and the second condition, the slope information can also be omitted from the map database 24.

[0092] In the above-described embodiments, as Figure 3 shown, the braking force control unit 15 sets the distribution of the regenerative braking force and the mechanical braking force to either one of the two stages of the first distribution R1 and the second distribution R2, but it can also be set to three or more stages. In short, when the first condition or the second condition is satisfied, the regenerative braking force can be suppressed compared to when the first condition or the second condition is not satisfied.

[0093] At least a part of the above-described embodiments and various variant examples can be arbitrarily combined.

[0094] [Explanation of Reference Numerals]

[0095] 1: Industrial vehicle

[0096] 6: Left traveling motor (traveling motor)

[0097] 7: Right traveling motor (traveling motor)

[0098] 8: Braking unit

[0099] 8a: FL Disc Brake (Mechanical Brake)

[0100] 8b: FR Disc Brake (Mechanical Brake)

[0101] 8c: RL Drum Brake (Mechanical Brake)

[0102] 8d: RR Drum Brake (Mechanical Brake)

[0103] 10: Controller

[0104] 11: Map Information Acquisition Unit

[0105] 12: Position Information Acquisition Unit

[0106] 13: Driving Information Acquisition Unit

[0107] 14: Autonomous Driving Control Unit

[0108] 15: Braking Force Control Unit

[0109] 100: Brake Control Device for Industrial Vehicle

[0110] R2: Second Distribution

[0111] R1: First Distribution.

Claims

1. A braking control device for an industrial vehicle, comprising a traveling motor that generates a regenerative braking force and a mechanical brake that generates a mechanical braking force as a braking unit, charging a battery using the regenerative braking force, and comprising: a map information acquisition unit that acquires map information; a position information acquisition unit that acquires the position information of the industrial vehicle; a traveling information acquisition unit that acquires the traveling information of the industrial vehicle; an automatic driving control unit that performs automatic driving control including calculating a required deceleration of the industrial vehicle based on the map information, the position information, and the traveling information; and a braking force control unit that controls the braking unit in such a manner that the distribution of the regenerative braking force and the mechanical braking force can be changed based on the required deceleration; the braking force control unit is based on the map information and the position information, determining whether a first condition that a prescribed first time has elapsed since the industrial vehicle started going downhill or a second condition that the industrial vehicle is going downhill on a downhill road with a prescribed gradient or more is satisfied; during the automatic driving of the industrial vehicle, when the first condition or the second condition is satisfied, controlling the braking unit with a first distribution in which the distribution ratio of the mechanical braking force is larger than a second distribution when neither the first condition nor the second condition is satisfied.

2. The braking control device for an industrial vehicle according to claim 1, wherein the braking force control unit is determining whether a prescribed second time has elapsed after the first condition is satisfied, or whether a release condition that the downhill has ended after the second condition is satisfied is satisfied, when the release condition is satisfied during the period of controlling the braking unit with the first distribution, ending the control of the braking unit with the first distribution.

3. The braking control device for an industrial vehicle according to claim 1 or 2, wherein the braking force control unit determines whether the first condition or the second condition is satisfied based on a regenerative current of the traveling motor.

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