Patent Description:
An industrial vehicle disclosed in <CIT> includes a controller, a direction sensor, and a direction lever. The controller controls the industrial vehicle. The direction sensor detects an operation direction of the direction lever determining a travel direction of the industrial vehicle. The direction sensor detects whether the direction lever is operated in a direction indicating a forward travel or a direction indicating a rearward travel, with respect to a neutral position as a reference position. The controller switches travel modes in response to an operation of the direction lever. The travel modes include a forward travel mode and a rearward travel mode. When the direction lever is in a forward position, the controller sets the industrial vehicle in the forward travel mode. When the direction lever is in a rearward position, the controller sets the industrial vehicle in the rearward travel mode. In a case in which a vehicle speed of the industrial vehicle is equal to or higher than a predetermined speed, even when a travel direction indicated by the direction lever is changed, the controller maintains the travel mode before the change. In this case, the travel direction indicated by the direction lever is opposite to a travel direction of the industrial vehicle.

The industrial vehicle may include an object detector. The object detector detects a position of an object present in a travel direction of the industrial vehicle. When the controller recognizes the travel direction indicated by the direction lever as the travel direction of the industrial vehicle, the travel direction recognized by the controller is opposite to the actual travel direction of the industrial vehicle from a point when a position of the direction lever is switched until a point when the travel direction of the industrial vehicle is switched. Here, the controller may not recognize the object present in the actual travel direction of the industrial vehicle.

In accordance with an aspect of the present invention, there is provided an industrial vehicle comprising a travel direction detector configured to detect a travel direction of the industrial vehicle; a vehicle speed sensor configured to detect a vehicle speed of the industrial vehicle; a travel direction determiner configured to determine the travel direction of the industrial vehicle; an object detector configured to detect a position of an object present in the travel direction of the industrial vehicle; and a controller, wherein the controller is set in a particular state when the vehicle speed of the industrial vehicle is equal to or higher than a first vehicle speed threshold value, and in the particular state, even when a travel direction command is changed by the travel direction determiner, the controller recognizes that a traveling state of the industrial vehicle before the travel direction command was changed continues at least until the vehicle speed of the forklift truck is lower than the first vehicle speed, thereby preventing a discrepancy between the travel direction of the forklift truck recognized by the controller and the actual travel direction of the forklift truck, and the object detector operates based on the traveling state of the industrial vehicle before the travel direction command was changed.

Other aspects and advantages of the invention will become apparent from the dependent claims and the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the embodiments together with the accompanying drawings in which:.

The following will describe an embodiment of an industrial vehicle according to the present invention.

As illustrated in <FIG>, a forklift truck <NUM> as an industrial vehicle includes a vehicle body <NUM>, two driving wheels <NUM>, two steering wheels <NUM>, and a load handling apparatus <NUM>. In the following description, terms of "front/rear", "forward/rearward", and "right/left" indicate orientations of the forklift truck <NUM>.

The vehicle body <NUM> includes an overhead guard <NUM> provided at an upper portion of a driver's seat. The two driving wheels <NUM> are arranged in a lower front portion of the vehicle body <NUM>, and spaced from each other in a vehicle width direction. The two steering wheels <NUM> are arranged in a lower rear portion of the vehicle body <NUM>, and spaced from each other in the vehicle width direction.

The load handling apparatus <NUM> includes a mast <NUM>, a pair of forks <NUM>, and a lift cylinder <NUM>. The mast <NUM> is provided in a front portion of the vehicle body <NUM>. The pair of forks <NUM> is movable up and down with the mast <NUM>. A load is loaded on the pair of forks <NUM>. The lift cylinder <NUM> is a hydraulic cylinder. The lift cylinder <NUM> is extendable and contractible to cause the mast <NUM> to move up and down. When the mast <NUM> moves up and down, the pair of forks <NUM> moves up and down accordingly. In the forklift truck <NUM> of the present embodiment, a driver performs a traveling operation and a load handling operation.

As illustrated in <FIG>, the forklift truck <NUM> includes a traveling system <NUM>, a controller <NUM>, an accelerator <NUM>, an accelerator sensor <NUM>, a steering angle sensor <NUM>, a direction lever <NUM>, a direction switch <NUM>, a forward connection line <NUM>, a rearward connection line <NUM>, a forward detection line <NUM>, a rearward detection line <NUM>, an interlock <NUM>, and an object detector <NUM>.

As illustrated in <FIG>, the traveling system <NUM> is a mechanism for a travel of the forklift truck <NUM>. The traveling system <NUM> includes an engine <NUM>, an output shaft <NUM>, a rotational speed sensor <NUM>, a power transmission <NUM>, a solenoid valve <NUM>, a forward solenoid <NUM>, a rearward solenoid <NUM>, a differential <NUM>, an axle <NUM>, a vehicle speed sensor <NUM>, and a travel controller <NUM>.

The engine <NUM> is a drive source for the traveling operation and the load handling operation of the forklift truck <NUM>. The engine <NUM> of the present embodiment is a gasoline engine using gasoline as fuel. The engine <NUM> includes a throttle actuator <NUM>. The throttle actuator <NUM> adjusts a throttle opening degree of a throttle valve (not illustrated) provided in an intake passage such that a rotational speed of the engine <NUM> follows a target rotational speed of the engine <NUM> calculated from an opening degree of the accelerator <NUM>. The throttle actuator <NUM> adjusts the throttle opening degree to adjust an amount of air supplied to the engine <NUM>. Thus, the rotational speed of the engine <NUM> is controlled. The engine <NUM> may be a diesel engine using diesel oil as fuel, or may be an engine using liquefied petroleum gas or compressed natural gas as fuel. The output shaft <NUM> is connected to the engine <NUM>. The engine <NUM> is driven to rotate the output shaft <NUM>.

The rotational speed sensor <NUM> is provided in the output shaft <NUM>. The rotational speed sensor <NUM> detects the rotational speed of the engine <NUM>. The rotational speed of the engine <NUM> corresponds to a rotational speed of the output shaft <NUM>. The rotational speed sensor <NUM> outputs electric signals in accordance with the rotational speed of the output shaft <NUM> to the travel controller <NUM>.

The power transmission <NUM> is configured to transmit a driving force of the engine <NUM> to the driving wheels <NUM>. The power transmission <NUM> includes a torque converter <NUM> and a transmission <NUM>.

The torque converter <NUM> is connected to the output shaft <NUM>. The driving force of the engine <NUM> is transmitted to the torque converter <NUM> through the output shaft <NUM>. The torque converter <NUM> includes a pump connected to the output shaft <NUM>, and a turbine. In the torque converter <NUM>, hydraulic oil discharged from the pump rotates the turbine.

The transmission <NUM> includes an input shaft <NUM>, a forward clutch <NUM>, a forward gear train <NUM>, a reverse clutch <NUM>, a reverse gear train <NUM>, and an output shaft <NUM>. The input shaft <NUM> is connected to the torque converter <NUM>. The driving force of the engine <NUM> is transmitted from the torque converter <NUM> to the transmission <NUM> through the input shaft <NUM>.

The forward clutch <NUM> is provided in the input shaft <NUM>. The forward gear train <NUM> is provided between the forward clutch <NUM> and the output shaft <NUM>. The forward clutch <NUM> is switchable between a connection state and a disconnection state. The connection state is a state where the input shaft <NUM> is connected to the forward gear train <NUM>. The disconnection state is a state where the input shaft <NUM> is disconnected from the forward gear train <NUM>. When the input shaft <NUM> is connected to the forward gear train <NUM> via the forward clutch <NUM>, the driving force of the engine <NUM> is transmitted from the input shaft <NUM> to the forward gear train <NUM>. Then, the driving force transmitted to the forward gear train <NUM> is transmitted to the output shaft <NUM>. When the forward clutch <NUM> is connected to the forward gear train <NUM>, the driving force of the engine <NUM> is transmitted to the output shaft <NUM>. When the forward clutch <NUM> is disconnected from the forward gear train <NUM>, the driving force of the engine <NUM> is not transmitted from the input shaft <NUM> to the forward gear train <NUM>. A hydraulic clutch is used as the forward clutch <NUM>. The hydraulic clutch is a wet multi-plate clutch, for example.

The reverse clutch <NUM> is provided in the input shaft <NUM>. The reverse gear train <NUM> is provided between the reverse clutch <NUM> and the output shaft <NUM>. The reverse clutch <NUM> is switchable between a connection state and a disconnection state. The connection state is a state where the input shaft <NUM> is connected to the reverse gear train <NUM>. The disconnection state is a state where the input shaft <NUM> is disconnected from the reverse gear train <NUM>. When the input shaft <NUM> is connected to the reverse gear train <NUM> via the reverse clutch <NUM>, the driving force of the engine <NUM> is transmitted from the input shaft <NUM> to the reverse gear train <NUM>. Then, the driving force transmitted to the reverse gear train <NUM> is transmitted to the output shaft <NUM>. When the reverse clutch <NUM> is connected to the reverse gear train <NUM>, the driving force of the engine <NUM> is transmitted to the output shaft <NUM>. When the reverse clutch <NUM> is disconnected from the reverse gear train <NUM>, the driving force of the engine <NUM> is not transmitted from the input shaft <NUM> to the reverse gear train <NUM>. A hydraulic oil clutch is used as the reverse clutch <NUM>. The hydraulic clutch is a wet multi-plate clutch, for example.

The solenoid valve <NUM> controls a supply and a discharge of the hydraulic oil to and from the forward clutch <NUM> and the reverse clutch <NUM>, which switches each of the clutches <NUM>, <NUM> between the connection state and the disconnection state.

The solenoids <NUM>, <NUM> respectively switch the supply and the discharge of the hydraulic oil to and from the clutches <NUM>, <NUM> by the solenoid valve <NUM>. When the forward solenoid <NUM> is energized, the hydraulic oil is supplied to the forward clutch <NUM> through the solenoid valve <NUM>. When the hydraulic oil is supplied to the forward clutch <NUM>, the forward clutch <NUM> is in the connection state. When the rearward solenoid <NUM> is energized, the hydraulic oil is supplied to the reverse clutch <NUM> through the solenoid valve <NUM>. When the hydraulic oil is supplied to the reverse clutch <NUM>, the reverse clutch <NUM> is in the connection state.

The solenoid valve <NUM> may be one electromagnetic directional switching valve. When the forward solenoid <NUM> is energized, a spool of the electromagnetic directional switching valve is switched to a position where the hydraulic oil is supplied to the forward clutch <NUM>. When the rearward solenoid <NUM> is energized, the spool of the electromagnetic directional switching valve is switched to a position when the hydraulic oil is supplied to the rearward clutch <NUM>. When the forward solenoid <NUM> and the rearward solenoid <NUM> are de-energized, the spool of the electromagnetic directional switching valve is switched to a position where the hydraulic oil is discharged from the clutches <NUM>, <NUM>. The hydraulic oil for operating the forward clutch <NUM> and the reverse clutch <NUM> is supplied to the forward clutch <NUM> and the reverse clutch <NUM> by a hydraulic pump positioned inside the power transmission <NUM>. The hydraulic pump has a known configuration.

Two solenoid valves may be used as the solenoid valve <NUM>. The two solenoid valves are provided in correspondence with the forward clutch <NUM> and the reverse clutch <NUM>, respectively. In this case, the forward solenoid <NUM> and the rearward solenoid <NUM> each control the solenoid valve <NUM> individually, so that the hydraulic oil is supplied to and discharged from the clutches <NUM>, <NUM>.

The power transmission <NUM> is switchable between a driving force transmission state where the driving force of the engine <NUM> is transmitted to the power transmission <NUM> and a driving force non-transmission state where the driving force of the engine <NUM> is not transmitted to the power transmission <NUM>. When one of the forward clutch <NUM> and the reverse clutch <NUM> is in the connection state, the driving force of the engine <NUM> is transmitted to the power transmission <NUM>, thereby causing the forklift truck <NUM> to travel. The driving force transmission state corresponds to a state where one of the forward clutch <NUM> and the reverse clutch <NUM> is in the connection state. When the forward clutch <NUM> and the reverse clutch <NUM> are in the disconnection state, the driving force of the engine <NUM> is not transmitted to the power transmission <NUM>. The driving force non-transmission state corresponds to a state where the forward clutch <NUM> and the reverse clutch <NUM> are in the disconnection state.

The differential <NUM> is connected to the output shaft <NUM>. The axle <NUM> is connected to the differential <NUM>. The driving wheels <NUM> are connected to the axle <NUM>. The axle <NUM> rotates with the rotation of the output shaft <NUM>. The driving wheels <NUM> rotate with the rotation of the axle <NUM> to cause the forklift truck <NUM> to travel. When the forward clutch <NUM> is connected to the forward gear train <NUM>, the forklift truck <NUM> travels forward. When the reverse clutch <NUM> is connected to the reverse gear train <NUM>, the forklift truck <NUM> travels rearward.

The vehicle speed sensor <NUM> is a sensor for detecting a vehicle speed of the forklift truck <NUM>. The vehicle speed sensor <NUM> is provided in the output shaft <NUM>, the axle <NUM>, or the like. The vehicle speed sensor <NUM> outputs pulse signals in accordance with the vehicle speed of the forklift truck <NUM> to the travel controller <NUM>.

The travel controller <NUM> is an engine control unit configured to control the engine <NUM>. The travel controller <NUM> controls the throttle actuator <NUM> to adjust the throttle opening degree. The driving force of the engine <NUM> is adjusted by the adjustment of the throttle opening degree.

As illustrated in <FIG>, the controller <NUM> includes a processor <NUM> and a memory <NUM>. The processor <NUM> is a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), a DSP (Digital Signal Processor), or the like. The memory <NUM> includes a RAM (Random Access Memory) and a ROM (Read Only Memory). The memory <NUM> stores program codes or commands configured to cause the processor <NUM> to execute processes. The memory <NUM>, that is, a computer readable medium, includes any available medium that is accessible by a general-purpose computer or a dedicated computer. The controller <NUM> may include a hardware circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). The controller <NUM>, which is a processing circuit, may include one or more processors for operating in accordance with computer programs, one or more hardware circuits such as the ASIC or the FPGA, or a combination thereof.

The accelerator sensor <NUM> detects an operation amount of the accelerator <NUM>. The operation amount of the accelerator <NUM> is also referred to as an accelerator opening degree. The accelerator sensor <NUM> outputs electric signals in accordance with the accelerator opening degree to the controller <NUM>. The controller <NUM> receives the electric signals from the accelerator sensor <NUM> to recognize the accelerator opening.

The steering angle sensor <NUM> detects a steering angle of each steering wheel <NUM>. The steering angle sensor <NUM> outputs electric signals in accordance with the steering angle to the controller <NUM>. The controller <NUM> receives the electric signals from the steering angle sensor <NUM> to recognize the steering angle.

The direction lever <NUM> determines a travel direction of the forklift truck <NUM>. The direction lever <NUM> is operated by the driver of the forklift truck <NUM>. The direction lever <NUM> is operated to be in a forward position indicating a forward travel or a rearward position indicating a rearward travel, with respect to a neutral position as a reference position. For example, the forward position is a position where the direction lever <NUM> is tilted forward from the neutral position, and the rearward position is a position where the direction lever <NUM> is tilted rearward from the neutral position. The direction lever <NUM> corresponds to a travel direction determiner in the present invention. The driver operates the direction lever <NUM> to give a travel direction command to the forklift truck <NUM>. The travel direction command is a command which instructs the forklift truck <NUM> on the travel direction of the forklift truck <NUM>. The travel direction command includes a forward travel command and a rearward travel command. The forward travel command is a command that instructs the forklift truck <NUM> to travel forward. The rearward travel command is a command that instructs the forklift truck <NUM> to travel rearward.

The direction switch <NUM> is switched in accordance with an operation direction of the direction lever <NUM>. The direction switch <NUM> includes one movable contact <NUM>, and three fixed contacts <NUM>, <NUM>, <NUM>. The movable contact <NUM> is connected to a positive electrode of a battery mounted on the forklift truck <NUM>. The three fixed contacts <NUM>, <NUM>, <NUM> correspond to a neutral fixed contact <NUM>, a forward fixed contact <NUM>, and a rearward fixed contact <NUM>, respectively. When the direction lever <NUM> is in the neutral position, the movable contact <NUM> is connected to the neutral fixed contact <NUM>. When the direction lever <NUM> is in the forward position, the movable contact <NUM> is connected to the forward fixed contact <NUM>. When the direction lever <NUM> is in the rearward position, the movable contact <NUM> is connected to the rearward fixed contact <NUM>. The direction switch <NUM> corresponds to a travel direction detector configured to detect the travel direction of the forklift truck <NUM> in the present invention. The direction switch <NUM> may include three buttons corresponding to the forward position, the neutral position, and the rearward position, which are each operated to connect the movable contact <NUM> to the corresponding fixed contact.

The forward connection line <NUM> connects the forward fixed contact <NUM> to the forward solenoid <NUM>. When the movable contact <NUM> is connected to the forward fixed contact <NUM>, the forward connection line <NUM> is electrically connected to the battery. With this connection, the forward solenoid <NUM> is energized. When the movable contact <NUM> is connected to the forward fixed contact <NUM>, the rearward solenoid <NUM> is de-energized.

The rearward connection line <NUM> connects the rearward fixed contact <NUM> to the rearward solenoid <NUM>. When the movable contact <NUM> is connected to the rearward fixed contact <NUM>, the rearward connection line <NUM> is electrically connected to the battery. With this connection, the rearward solenoid <NUM> is energized. When the movable contact <NUM> is connected to the rearward fixed contact <NUM>, the forward solenoid <NUM> is de-energized.

When the direction lever <NUM> is in the forward position, the forward solenoid <NUM> is energized to supply the hydraulic oil to the forward clutch <NUM>. This enables the forklift truck <NUM> to travel forward. When the direction lever <NUM> is in the rearward position, the rearward solenoid <NUM> is energized to supply the hydraulic oil to the reverse clutch <NUM>. This enables the forklift truck <NUM> to travel rearward. When the direction lever <NUM> is in the neutral position, the solenoids <NUM>, <NUM> are de-energized. Thus, the hydraulic oil is not supplied to the clutches <NUM>, <NUM>. In this case, the driving force of the engine <NUM> is not transmitted to the power transmission <NUM>.

The forward detection line <NUM> connects the forward connection line <NUM> to the controller <NUM>. When a voltage is applied from the battery to the forward connection line <NUM>, the voltage is applied to the controller <NUM> through the forward detection line <NUM>. The rearward detection line <NUM> connects the rearward connection line <NUM> to the controller <NUM>. When the voltage is applied from the battery to the rearward connection line <NUM>, the voltage is applied to the controller <NUM> through the rearward detection line <NUM>. When the voltage is input from the forward detection line <NUM>, the controller <NUM> determines that the direction lever <NUM> is in the forward position. When the voltage is input from the rearward detection line <NUM>, the controller <NUM> determines that the direction lever <NUM> is in the rearward position. In detail, the controller <NUM> includes a port <NUM> that is connected to the forward detection line <NUM> and a port <NUM> that is connected to the rearward detection line <NUM>. When the voltage is input to the port <NUM>, the controller <NUM> determines that the direction lever <NUM> is in the forward position. When the voltage is input to the port <NUM>, the controller <NUM> determines that the direction lever <NUM> is in the rearward position. When the voltage is not input from any of the forward detection line <NUM> and the rearward detection line <NUM>, the controller <NUM> determines that the direction lever <NUM> is in the neutral position. When the direction lever <NUM> is in the forward position, the controller <NUM> determines that the forward travel command is input to the controller <NUM>. When the direction lever <NUM> is in the rearward position, the controller <NUM> determines that the rearward travel command is input to the controller <NUM>.

The interlock <NUM> includes a forward relay <NUM> and a rearward relay <NUM>. The forward relay <NUM> is provided in the forward connection line <NUM>. The forward relay <NUM> is switched between a connection state and a disconnection state. When the forward relay <NUM> is in the connection state, the forward connection line <NUM> is electrically connected to the forward solenoid <NUM>. When the forward relay <NUM> is in the disconnection state, the forward connection line <NUM> is electrically disconnected from the forward solenoid <NUM>. The rearward relay <NUM> is provided in the rearward connection line <NUM>. The rearward relay <NUM> is switched between a connection state and a disconnection state. When the rearward relay <NUM> is in the connection state, the rearward connection line <NUM> is electrically connected to the rearward solenoid <NUM>. When the rearward relay <NUM> is in the disconnection state, the rearward connection line <NUM> is electrically disconnected from the rearward solenoid <NUM>.

The object detector <NUM> includes a stereo camera <NUM>, a detector <NUM>, and an alarm <NUM>. The stereo camera <NUM> includes two cameras and captures an image. As illustrated in <FIG>, the stereo camera <NUM> is disposed in the overhead guard <NUM>. The stereo camera <NUM> is disposed so as to capture an aerial view image of a road surface on which the forklift truck <NUM> travels, from above the forklift truck <NUM>. The stereo camera <NUM> of the present embodiment captures a rear of the forklift truck <NUM>. Thus, an object detected by the object detector <NUM> is located in the rear of the forklift truck <NUM>. A direction in which the object detector <NUM> detects the object orients to the rear of the forklift truck <NUM>. The alarm <NUM>, the detector <NUM>, and the stereo camera <NUM> may be made into a unit to be disposed on the overhead guard <NUM>. The alarm <NUM> and the detector <NUM> may be disposed at a position different from a position where the overhead guard <NUM> is disposed.

The detector <NUM> includes a processor <NUM> and a memory <NUM>. The processor <NUM> is a CPU, a GPU, or a DSP, for example. The memory <NUM> includes a RAM and a ROM. The memory <NUM> stores various programs for detecting an object in the image captured by the stereo camera <NUM>. The memory <NUM> stores program codes or commands configured to cause the processor <NUM> to execute processes. The memory <NUM>, that is, a computer readable medium, includes any available medium that is accessible by a general-purpose computer or a dedicated computer. The detector <NUM> may include a hardware circuit such as an ASIC or an FPGA. The detector <NUM>, which is a processing circuit, may include one or more processors for operating in accordance with computer programs, one or more hardware circuits such as the ASIC or the FPGA, or a combination thereof.

The detector <NUM> detects the object present in the rear of the forklift truck <NUM> by repeating an object detection process as described below in a predetermined control period. The detector <NUM> derives a position of the detected object. The position of the object is a relative position between the forklift truck <NUM> and the object.

As illustrated in <FIG>, in Step S100, the detector <NUM> obtains an image from the stereo camera <NUM>.

Next, in Step S110, the detector <NUM> performs a stereo process to obtain a disparity image. The disparity image is an image whose pixels are correlated with a disparity [px]. The disparity image is not necessarily visualized data, and corresponds to data in which the disparity is correlated with each pixel of the disparity image. Two images captured by the stereo camera <NUM> are compared with each other, and a difference in pixel counts between the two images is derived for the same feature point in each of the two images, so that a disparity is obtained. The feature point is a visually recognizable point as a border such as an edge of an obstacle. The feature point is detectable by using information of brightness, and the like.

Next, in Step S120, the detector <NUM> derives coordinates of the feature point in a world coordinate system corresponding to a coordinate system in a real space. The world coordinate system has an X-axis extending in the vehicle width direction of the forklift truck <NUM> when the forklift truck <NUM> is located on a horizontal surface, a Y-axis orthogonal to the X-axis of horizontal directions, and a Z-axis extending vertically. Coordinates of the feature point in a camera coordinate system is derived from a base line length of the stereo camera <NUM>, a focal length of the stereo camera <NUM>, and the disparity image obtained in Step S110. Such coordinates of the feature point in the camera coordinate system are transformed to coordinates of the feature point in the world coordinate system. Thus, the coordinates of the feature point are derived. As illustrated in <FIG>, an X-axis direction, a Y-axis direction, and a Z-axis direction are represented by arrows X, Y, and Z.

As illustrated in <FIG>, in Step S130, the detector <NUM> extracts an object by clustering the feature points. The detector <NUM> defines, as one point group, a set of feature points assumed to represent the same object among the feature points representing a part of the object, and extracts the one point group as the object. The detector <NUM> performs clustering to recognize the feature points positioned in a predetermined range as one point group based on the coordinates of the feature points in the world coordinate system derived in Step S120. The detector <NUM> recognizes the clustered point group as one object. The clustering of the feature points in Step S130 may be performed by various methods.

Next, in Step S140, the detector <NUM> derives coordinates of the object in the world coordinate system. The coordinates of the object are derivable from the coordinates of the feature points forming the point group. The coordinates of the object in the world coordinate system represent a relative position between the forklift truck <NUM> and the object. Specifically, regarding the coordinates of the object in the world coordinate system, an X-coordinate represents a distance from an origin to the object in the right-left direction, and a Y-coordinate represents a distance from the origin to the object in the front-rear direction. The origin corresponds to, for example, coordinates in which the X-coordinate and the Y-coordinate represent a position of the stereo camera <NUM> and a Z-coordinate represents the road surface. Euclidean distance from the position of the stereo camera <NUM> to the object is derivable from the X-coordinate and the Y-coordinate. The Z-coordinate of the coordinates of the object in the world coordinate system represents a height of the object from the road surface.

Next, in Step S150, the detector <NUM> performs a person detection process. The detector <NUM> determines whether the object is a person in the person detection process. In the present embodiment, the detector <NUM> performs the person detection process on an image captured by one of the two cameras of the stereo camera <NUM>. The detector <NUM> transforms the coordinates of the object in the world coordinate system which are obtained in Step S140 into camera coordinates, and then, transforms the camera coordinates into coordinates of the image captured by the camera. The detector <NUM> performs the person detection process on the coordinates of the object in the image. The person detection process is, for example, performed using features. The detector <NUM> extracts features of the coordinates of the object on the image. A method of feature extraction is used, wherein features in a local area of an image, for example, HOG: Histogram of Oriented Gradients features and Haar-Like features, are extracted. The detector <NUM> determines whether the object is a person by comparing the features extracted from the image with dictionary data. The dictionary data is, for example, data of features extracted from a plurality of image data on which a person is captured. In the following description, the object other than a person may be called an obstacle.

The alarm <NUM> is a device that issues an alarm to the driver of the forklift truck <NUM>. Examples of the alarm <NUM> include a buzzer that emits sounds, a lamp that emits light, and a combination thereof.

The controller <NUM>, the travel controller <NUM>, and the object detector <NUM> obtain information from each other. The controller <NUM>, the travel controller <NUM>, and the object detector <NUM> obtain the information from each other through communication in accordance with a communication protocol for the vehicle, such as CAN (Controller Area Network) or LIN (Local Interconnect Network).

The controller <NUM> derives the vehicle speed of the forklift truck <NUM>. The vehicle speed of the forklift truck <NUM> is derivable from a detection result of the vehicle speed sensor <NUM>, a gear ratio, an outer diameter of each driving wheel <NUM>, the steering angle detected by the steering angle sensor <NUM>, and the like. The detection result of the vehicle speed sensor <NUM> is obtainable from the travel controller <NUM>. The memory <NUM> only need store the gear ratio and the outer diameter of each driving wheel <NUM> in advance. In the following description, the vehicle speed means the vehicle speed of the forklift truck <NUM>.

The controller <NUM> switches the forward relay <NUM> and the rearward relay <NUM> between the connection state and the disconnection state. When a switchback operation is not performed, the controller <NUM> sets the forward relay <NUM> and the rearward relay <NUM> in the connection state. When the switchback operation is performed at the vehicle speed equal to or higher than a second vehicle speed threshold value, the controller <NUM> sets the forward relay <NUM> and the rearward relay <NUM> in the disconnection state. In response to the vehicle speed lower than the second vehicle speed threshold value, the controller <NUM> sets the forward relay <NUM> and the rearward relay <NUM> in the connection state. In the switchback operation, the direction lever <NUM> is operated to switch the travel direction command from the forward travel command to the rearward travel command or from the rearward travel command to the forward travel command. When each of the forward relay <NUM> and the rearward relay <NUM> is in the disconnection state, the solenoids <NUM>, <NUM> are de-energized regardless of the position of the direction lever <NUM>, so that the driving force of the engine <NUM> is not transmitted to the power transmission <NUM>. That is, the power transmission <NUM> is set in the driving force non-transmission state. This reduces a load on the power transmission <NUM> when the switchback operation is performed at the vehicle speed equal to or higher than the second vehicle speed threshold value. As the second vehicle speed threshold value is lower, the load on the power transmission <NUM> is reduced. On the other hand, as the second vehicle speed threshold value is lower, a time from a point when the direction lever <NUM> is operated until the travel direction of the forklift truck <NUM> is switched becomes longer in the switchback operation. The second vehicle speed threshold value may be set to any value based on these factors.

The controller <NUM> transmits an alarm command to the object detector <NUM> to activate the alarm <NUM>. Specifically, the object detector <NUM> includes an activation portion configured to activate the alarm <NUM> upon reception of the alarm command.

The controller <NUM> performs an alarm control. In the alarm control, while the forklift truck <NUM> travels, the alarm <NUM> issues an alarm depending on a status of object detection by the object detector <NUM>. Firstly, the following will describe an alarm area used for the alarm control.

As illustrated in <FIG>, an alarm area AA1 used for the alarm control is set within an object detectable range of the object detector <NUM>. The object detectable range of the object detector <NUM> corresponds to an imaging range to be captured by the stereo camera <NUM>. In the present embodiment, the alarm area AA1 is the same area as the object detectable range of the object detector <NUM>. The alarm area AA1 expands from the position of the stereo camera <NUM> toward the rear of the forklift truck <NUM>, and extends in the vehicle width direction of the forklift truck <NUM>. The alarm area AA1 is defined by the X-coordinate and the Y-coordinate in the world coordinate system.

The controller <NUM> derives a predicted orbit T of the forklift truck <NUM>. The predicted orbit T is an orbit on which the forklift truck <NUM> is predicted to pass. In the present embodiment, the controller <NUM> derives the predicted orbit T on which the forklift truck <NUM> is predicted to pass when the travel direction of the forklift truck <NUM> is a rearward travel direction.

The predicted orbit T is derived from the steering angle of each steering wheel <NUM> and size information of the forklift truck <NUM>. The size information of the forklift truck <NUM> includes a size [mm] from a central axis of each driving wheel <NUM> to a rear end of the vehicle body <NUM>, a wheelbase [mm], and a vehicle width [mm]. Since the size information of the forklift truck <NUM> is predetermined, the size information may be stored in the memory <NUM> of the controller <NUM>, or the like in advance. The predicted orbit T is formed between an orbit LT on which a left end LE of the vehicle body <NUM> passes and an orbit on which a right end RE of the vehicle body <NUM> passes. The controller <NUM> derives the X-coordinate and the Y-coordinate of the predicted orbit T extending rearward from the forklift truck <NUM> in the world coordinate system.

As illustrated in <FIG> and <FIG>, when the forklift truck <NUM> travels straight, the predicted orbit T extends in the rear travel direction of the forklift truck <NUM> therefrom. As illustrated in <FIG>, when the forklift truck <NUM> turns, the predicted orbit T turns in the rear travel direction of the forklift truck <NUM> therefrom. When the forklift truck <NUM> turns in a right direction, the predicted orbit T extends in the right direction. When the forklift truck <NUM> turns in a left direction, the predicted orbit T extends in the left direction. That is, when the forklift truck <NUM> turns, the controller <NUM> derives the predicted orbit T extending in a turning direction of the forklift truck <NUM>.

The forklift truck <NUM> illustrated in <FIG> has the vehicle speed higher than that of the forklift truck <NUM> illustrated in <FIG>. Similarly, the forklift truck <NUM> illustrated in <FIG> has the vehicle speed higher than that of the forklift truck <NUM> illustrated in <FIG>. As illustrated in <FIG>, the controller <NUM> has the predicted orbit T that extends longer in the travel direction of the forklift truck <NUM> as the vehicle speed of the forklift truck <NUM> is higher. In the present embodiment, an orbit derived threshold value YT changes depending on the vehicle speed of the forklift truck <NUM>. The orbit derived threshold value YT is set for the Y-coordinate in the world coordinate system, and the Y-coordinate of the orbit derived threshold value YT is further distant from the forklift truck <NUM> as the vehicle speed of the forklift truck <NUM> is higher. The controller <NUM> derives the predicted orbit T from the forklift truck <NUM> to the orbit derived threshold value YT. With regard to the point in which as the vehicle speed of the forklift truck <NUM> is higher, the predicted orbit T extends longer in the travel direction of the forklift truck <NUM>, the vehicle speed of the forklift truck <NUM> need not be in proportion to a length of the predicted orbit T extending in the travel direction of the forklift truck <NUM>. The vehicle speed of the forklift truck <NUM> and the length of the predicted orbit T extending in the travel direction of the forklift truck <NUM> only need have a correlation in which as the vehicle speed of the forklift truck <NUM> is higher, the predicted orbit T extends longer in the travel direction of the forklift truck <NUM>. The predicted orbit T is derived within the alarm area AA1.

The following will describe the alarm control of the present embodiment. The alarm control is repeated every specified control period.

As illustrated in <FIG>, in Step S1, the controller <NUM> determines whether a particular condition is satisfied. The particular condition is that a state in which the vehicle speed of the forklift truck <NUM> is lower than a first vehicle speed threshold value continues for a predetermined time. The vehicle speed of the forklift truck <NUM> is an absolute value of a speed calculated using the detection result of the vehicle speed sensor <NUM>. The first vehicle speed threshold value may be set to any value. In the present embodiment, the first vehicle speed threshold value is lower than the second vehicle speed threshold value. The predetermined time is longer than the control period. The predetermined time is set such that the controller <NUM> does not determine that the particular condition is satisfied when the vehicle speed of the forklift truck <NUM> is determined to be momentary lower than the first vehicle speed threshold value despite the vehicle speed of the forklift truck <NUM> equal to or higher than the first vehicle speed threshold value, which is caused by an effect of noise. When the detection result in Step S1 is YES, the controller <NUM> proceeds to Step S2. When the detection result in Step S1 is NO, the controller <NUM> proceeds to Step S3. When the particular condition is not satisfied, the vehicle speed of the forklift truck <NUM> is equal to or higher than the first vehicle speed threshold value. That is, the process in Step S3 is performed when the vehicle speed of the forklift truck <NUM> is higher than the first vehicle speed threshold value.

In Step S2, the controller <NUM> is set in a normal state. In the normal state, the controller <NUM> determines the travel direction of the forklift truck <NUM> from the detection result of the direction switch <NUM>. The controller <NUM> determines that the travel direction of the forklift truck <NUM> is the forward travel direction when the direction lever <NUM> is in the forward position. The controller <NUM> determines that the travel direction of the forklift truck <NUM> is the rearward travel direction when the direction lever <NUM> is in the rearward position. The controller <NUM> ends the process in Step S2, and then, proceeds to Step S4.

In Step S3, the controller <NUM> is set in a particular state. In the particular state, even when the travel direction command is changed by the direction lever <NUM>, the controller <NUM> recognizes that a traveling state of the forklift truck <NUM> before the travel direction command is changed continues. When the travel direction command in the last control period is the forward travel command, the controller <NUM> determines that the forward travel command continues even when the rearward travel command is input by the direction switch <NUM>. When the travel direction command in the last control period is the rearward travel command, the controller <NUM> determines that the rearward travel command continues even when the forward travel command is input by the direction switch <NUM>. That is, while the particular state continues, the travel direction command does not change depending on the operation of the direction lever <NUM>. When the controller <NUM> is set in the particular state, the vehicle speed is equal to or higher than the first vehicle speed threshold value. The second vehicle speed threshold value is larger than the first vehicle speed threshold value. Thus, the controller <NUM> sets the power transmission <NUM> in the driving force non-transmission state when the controller <NUM> is in the particular state and the vehicle speed of the forklift truck <NUM> is equal to or higher than the second vehicle speed threshold value. The controller <NUM> ends the process in Step S3, and then, proceeds to Step S4.

In Step S4, the controller <NUM> determines whether the alarm condition is satisfied. The alarm condition is provided to determine whether the alarm <NUM> issues an alarm. The alarm condition is satisfied when there is a possibility that the forklift truck <NUM> and the object are brought into contact with each other. The alarm condition is changed depending on whether the object is a person or an obstacle. When the detection result in Step S4 is YES, that is, the alarm condition is satisfied, the controller <NUM> proceeds to Step S5. In Step S5, the controller <NUM> causes the alarm <NUM> to issue an alarm. The following will describe the alarm condition of the present embodiment. The travel direction used for the determination of the alarm condition is changed depending on whether the controller <NUM> is in the normal state or in the particular state. When the controller <NUM> is in the normal state, the travel direction of the forklift truck <NUM> is determined from the detection result of the direction switch <NUM>. When the controller <NUM> is in the particular state, the travel direction of the forklift truck <NUM> is determined from the travel direction command in the last control period. In the particular state, the controller <NUM> determines whether there is the possibility that the object and the forklift truck <NUM> are brought into contact with each other based on the traveling state of the forklift truck <NUM> before the travel direction command is changed.

The alarm condition when the object is a person is that the forklift truck <NUM> travels rearward and the person is present in the alarm area AA1. When the object detected by the object detector <NUM> is a person, the alarm <NUM> issues an alarm when the forklift truck <NUM> travels rearward and the person is present in the alarm area AA1. Here, when a person is present in the predicted orbit T, the alarm may be intensified as compared with the case where the people is present outside the predicted orbit T. In order to intensify the alarm, for example, when the alarm <NUM> is a buzzer, the buzzer is sounded louder. When the alarm <NUM> is a combination of a lamp and a buzzer, the alarm using one of the lamp and the buzzer may be switched to the alarm using both the lamp and the buzzer. With this mechanism, the driver may easily recognize that the object is present in the predicted orbit T.

The alarm condition when the object is an obstacle is that the forklift truck <NUM> travels rearward and the obstacle is present in the predicted orbit T. When the object detected by the object detector <NUM> is an obstacle, the alarm <NUM> issues an alarm when the forklift truck <NUM> travels rearward and the obstacle is present in the predicted orbit T.

As illustrated in <FIG>, the forklift truck <NUM> travels rearward and an object O1 is present in the rear of the forklift truck <NUM>. The arrow D1 indicates the actual travel direction of the forklift truck <NUM>. The arrow D2 indicates the travel direction of the forklift truck <NUM> recognized by the controller <NUM>. When the driver of the forklift truck <NUM> performs the switchback operation, the rearward travel command is switched to the forward travel command by the direction lever <NUM>. When the travel direction of the forklift truck <NUM> is switched, the vehicle speed of the forklift truck <NUM> decreases. For example, when the travel direction of the forklift truck <NUM> is switched from the rearward travel direction to the forward travel direction, the position of the direction lever <NUM> is changed to the forward travel position, and then, the vehicle speed of the forklift truck <NUM> decreases. In response to the vehicle speed of the forklift truck <NUM> reaching <NUM>/h, the travel direction of the forklift truck <NUM> is switched to the forward travel direction. When the travel direction command is changed by the direction lever <NUM> at the vehicle speed of the forklift truck <NUM> equal to or higher than the first vehicle speed threshold value, the travel direction of the forklift truck <NUM> is maintained at least until the vehicle speed of the forklift truck <NUM> is lower than the first vehicle speed threshold value.

The following will assume that the controller <NUM> is maintained in the normal state regardless of the vehicle speed of the forklift truck <NUM>. When the position of the direction lever <NUM> is changed to the forward travel position, the controller <NUM> recognizes the actual travel direction of the forklift truck <NUM> as the forward travel direction. Here, even when the forklift truck <NUM> actually continues to travel rearward, the alarm issued by the alarm <NUM> stops at the point when the position of the direction lever <NUM> is changed to the forward travel position. That is, although a distance L1 between the forklift truck <NUM> and the object O1 decreases, the alarm issued by the alarm <NUM> stops at the point when the position of the direction lever <NUM> is changed to the forward travel position.

In contrast, in the present embodiment, when the vehicle speed of the forklift truck <NUM> is equal to or higher than the first vehicle speed threshold value, the controller <NUM> is set in the particular state. In the particular state, even when the travel direction command is changed by the direction lever <NUM>, the controller <NUM> recognizes that the traveling state of the forklift truck <NUM> before the travel direction command is changed continues. As illustrated in <FIG>, even when the rearward travel command is changed to the forward travel command by the switchback operation of the forklift truck <NUM>, the controller <NUM> recognizes that the rearward travel command continues. Thus, the controller <NUM> recognizes that the travel direction of the forklift truck <NUM> is the rearward travel direction until the vehicle speed of the forklift truck <NUM> is lower than the first vehicle speed threshold value. Even when the travel direction command is changed by the direction lever <NUM>, the object detector <NUM> operates based on the traveling state before the travel direction command is changed, so that the object is detectable in correspondence with the travel direction of the forklift truck <NUM>. The operating of the object detector <NUM> means that the object detector <NUM> detects the position of the object present in the travel direction of the forklift truck <NUM>. Even when the forklift truck <NUM> continues to travel inertially, the alarm issued by the alarm <NUM> is continuable until the vehicle speed of the forklift truck <NUM> is lower than the first vehicle speed threshold value. In a case where the conditions of the vehicle speed of the forklift truck <NUM>, and the like when the switchback operation is performed are the same as those in <FIG>, the distance L1 between the forklift truck <NUM> and the object O1 when the alarm issued by the alarm <NUM> stops may be shorten as compared with the case illustrated in <FIG>.

The embodiment may be modified as follows. The embodiment and the following modified examples may be combined with each other as long as they do not technically contradict each other.

As illustrated in <FIG>, the traveling system <NUM> may include a brake mechanism <NUM>. The brake mechanism <NUM> includes a brake actuator <NUM>, brake wheel cylinders <NUM>, and a brake controller <NUM>.

The brake actuator <NUM> is an actuator that controls hydraulic oil to be supplied to the brake wheel cylinders <NUM>. The brake actuator <NUM> controls the supply of the hydraulic oil with a solenoid valve, for example.

The brake wheel cylinders <NUM> are provided in the driving wheels <NUM>, respectively. The brake wheel cylinders <NUM> may be provided in the steering wheels <NUM>, respectively. The brake wheel cylinders <NUM> each press a brake pad against brake discs with the hydraulic oil supplied from the brake actuator <NUM> to generate a friction braking force.

A hardware configuration of the brake controller <NUM> is the same as that of the controller <NUM>, for example. The brake controller <NUM> controls the brake actuator <NUM> upon reception of a command from the controller <NUM>. Thus, the controller <NUM> controls the brake mechanism <NUM> by transmitting the command to the brake controller <NUM>.

The controller <NUM>, in the particular state, may apply the braking force to the forklift truck <NUM> by controlling the brake mechanism <NUM>, instead of a control in which the power transmission <NUM> is set in the driving force non-transmission state. The controller <NUM>, in the particular state, may apply the braking force to the forklift truck <NUM> by controlling the brake mechanism <NUM>, in addition to the control in which the power transmission <NUM> is set in the driving force non-transmission state.

The controller <NUM> need not set the power transmission <NUM> in the driving force non-transmission state in the particular state. In this case, the forklift truck <NUM> need not include the interlock <NUM>.

The alarm condition need not be changed depending on whether the object is a person or an obstacle. In this case, the detector <NUM> need not perform a person detection process. The alarm condition may be that the forklift truck <NUM> travels rearward and the object is present within the predicted orbit T. The alarm condition may be that the forklift truck <NUM> travels rearward and the object is present within the alarm area AA1. When the predicted orbit T is not used as the alarm condition, the controller <NUM> need not derive the predicted orbit T.

The controller <NUM> may perform a control for decreasing the vehicle speed of the forklift truck <NUM> by recognizing the travel direction of the forklift truck <NUM>. For example, when the alarm condition is satisfied, the controller <NUM> may perform the control for decreasing the vehicle speed of the forklift truck <NUM>. Here, the alarm <NUM> may or need not issue an alarm.

The controller <NUM> may use an inching valve to set the power transmission <NUM> in the driving force non-transmission state. The inching valve performs an adjustment such that the driving force of the engine <NUM> is distributed to the power transmission <NUM> or to the hydraulic pump. The inching valve may perform an adjustment such that the driving force of the engine <NUM> is not distributed to the power transmission <NUM> so that the power transmission <NUM> is set in the driving force non-transmission state.

The particular condition may be that the vehicle speed of the forklift truck <NUM> is lower than the first vehicle speed threshold value.

The power transmission <NUM> may be switchable between the driving force transmission state and the driving force non-transmission state upon reception of a command from the controller <NUM>. In this case, when the switchback operation is performed, the controller <NUM> may give the command to the power transmission <NUM> so that the power transmission <NUM> is set in the driving force non-transmission state.

The object detector <NUM> may detect a position of an object present in the forward travel direction of the travel direction of the forklift truck <NUM>. In this case, the stereo camera <NUM> is disposed so as to orient the front of the forklift truck <NUM>. When the position of the object present in the forward travel direction of the forklift truck <NUM> is detected by the object detector <NUM>, the alarm area AA1 is defined as an area expanding forward from the forklift truck <NUM>. Here, in the alarm control, "rear" and "front" described in the embodiment are replaced with each other.

The object detector <NUM> may detect a position of an object present in both the forward travel direction and the rear travel direction of the travel direction of the forklift truck <NUM>. For example, a stereo camera for capturing the front of the forklift truck <NUM> and a stereo camera for capturing the rear of the forklift truck <NUM> or a fish-eye camera may be disposed. In this case, the alarm area AA1 includes a forward area expanding forward from the forklift truck <NUM> and a rearward area expanding rearward from the forklift truck <NUM>. The controller <NUM> changes the alarm condition in accordance with the travel direction of the forklift truck <NUM>. For example, the controller <NUM>, when the travel direction of the forklift truck <NUM> is the rearward travel direction, causes the alarm <NUM> to issue an alarm based on the alarm condition which is the same as that in the embodiment. The controller <NUM>, when the travel direction of the forklift truck <NUM> is the forward travel direction, causes the alarm <NUM> to issue an alarm based on the alarm condition in which the rearward travel is replaced with the forward travel in the alarm condition of the embodiment.

Any device may be used as the travel direction determiner as long as the device is operable by the driver of the forklift truck <NUM>. The travel direction determiner may be, for example, a push-button.

A monocular camera, a ToF (Time of Flight) camera, a LIDAR (Laser Imaging Detection and Ranging), a millimeter wave radar, or the like may be used as the object detector <NUM>, instead of the stereo camera <NUM>. The object detector <NUM> may include a combination of a plurality of sensors, such as the stereo camera <NUM> and the LIDAR.

The alarm <NUM> may be provided in any device other than the object detector <NUM>.

The alarm <NUM> may be directly operated by the controller <NUM>.

The operation of the forklift truck <NUM> may be switchable between a manual mode and an automatic mode.

The forklift truck <NUM> may be an electric forklift truck that performs a travel operation by the motor.

The forklift truck <NUM> may perform both a vehicle speed command and determination of the travel direction by the direction lever. This type of forklift truck is a reach-type forklift truck, for example.

The rotational speed sensor <NUM> may be used as the travel direction detector.

The detector <NUM> may be used as the controller.

Claim 1:
An industrial vehicle (<NUM>) comprising:
a travel direction detector (<NUM>) configured to detect a travel direction of the industrial vehicle (<NUM>);
a vehicle speed sensor (<NUM>) configured to detect a vehicle speed of the industrial vehicle (<NUM>);
a travel direction determiner (<NUM>) configured to determine the travel direction of the industrial vehicle (<NUM>);
an object detector (<NUM>) configured to detect a position of an object present in the travel direction of the industrial vehicle (<NUM>); and
a controller (<NUM>), characterized in that
the controller (<NUM>) is set in a particular state when the vehicle speed of the industrial vehicle (<NUM>) is equal to or higher than a first vehicle speed threshold value, and
in the particular state, even when a travel direction command is changed by the travel direction determiner (<NUM>), the controller (<NUM>) recognizes that a traveling state of the industrial vehicle (<NUM>) before the travel direction command was changed continues at least until the vehicle speed of the forklift truck (<NUM>) is lower than the first vehicle speed threshold value, thereby preventing a discrepancy between the travel direction of the forklift truck (<NUM>) recognized by the controller (<NUM>) and the actual travel direction of the forklift truck (<NUM>), and the object detector (<NUM>) operates based on the traveling state of the industrial vehicle (<NUM>) before the travel direction command was changed.