CROSS-REFERENCE

This application is a US National Stage Application under 35 U.S.C. § 371 of International Application No. PCT/JP2019/015798 filed Apr. 11, 2019, which claims foreign priority of JP2018-098271 filed May 22, 2018, the disclosures of which are hereby incorporated by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a work vehicle including a boarding-type driver unit and a foot brake for braking a driving device.

BACKGROUND ART

Some passenger cars use a driving support device and a driving support method in which emergency brake control is performed when there is a risk of collision with a preceding vehicle (for example, refer to PTL 1).

CITATION LIST

Patent Literature

PTL 1: Japanese Unexamined Patent Publication No. 2017-43193

DISCLOSURE OF INVENTION

Problems to be Solved by the Invention

In recent years, work vehicles, such as tractors, have been automated to enable autonomous driving of work vehicles through the use of satellite positioning systems (navigation satellite system (NSS)), such as a global positioning system (GPS). Advancement in such automation of work vehicles leads to the realization of unmanned work vehicles that are capable of autonomous driving of the unmanned work vehicles. In order to realize such an unmanned work vehicle that is capable of autonomous driving, the work vehicle needs to have an emergency brake function for quickly stopping the work vehicle when an error occurs in the control system related to autonomous driving, such as a speed change control system and a steering control system.

Therefore, it is conceivable that the emergency brake function adopted in passenger cars be applied to the work vehicles. However, the emergency brake function adopted in passenger cars is a driving support device or a driving support method such as those described in PTL 1, which are intended for the prevention of collision with a preceding vehicle and the reduction of collision damage. For this reason, it is necessary to develop a unique emergency brake function in order to solve the above problems.

Since a work vehicle capable of unmanned autonomous driving is originally configured to be driven by a passenger, the emergency brake function must not hinder the manual driving by the passenger.

In view of such a situation, a main object of the present invention is to provide an emergency brake function capable of quickly stopping a work vehicle when an error occurs inside the vehicle.

Means for Solving the Problems

A first characteristic configuration of the present invention is in a work vehicle including:

a boarding-type driver unit;

a foot brake that brakes a driving device;

an autonomous drive unit that enables autonomous drive of a vehicle; and

an electric actuator that switches the foot brake between a braking state for braking the driving device and a released state for releasing the braking, wherein,

the driver unit includes a mode selector that enables selection of an autonomous drive mode in which the autonomous drive unit autonomously drives the vehicle,

the autonomous drive unit includes a control unit that controls an operation of the electric actuator, and

in the autonomous drive mode, if an error is detected inside the vehicle based on detection information from a vehicle state detection device that detects a state of each component in the vehicle, or if an emergency stop command is obtained from a wireless communication device that is capable of wireless communication with the autonomous drive unit, the control unit controls the operation of the electric actuator and switches the foot brake from the released state to the braking state.

According to this configuration, if an error occurs inside the vehicle, the electric actuator switches the foot brake to the braking state under the control of the control unit when the control unit detects an error inside the vehicle on the basis of detection information from the vehicle state detection device or when the control unit obtains an emergency stop command sent by an outside administrator through the wireless communication device in response to noticing an error. As a result, the work vehicle can be quickly braked and stopped.

In this way, even if an error occurs inside the vehicle in an unmanned drive state in which the tractor autonomously drives without a passenger, the work vehicle can be quickly braked and stopped.

Since the foot brake is highly reliable and does not cause problems even when it is frequently used during manual driving by the passenger, it is possible to certainly stop brake and stop the work vehicle in an unmanned state.

By using the foot brake for an emergency stop, it is possible to avoid the complication of the structure due to introduction of a new brake dedicated to the emergency stop.

In a second characteristic configuration,

the driver unit includes an operating tool for brake release, and

if the operation tool is manually operated in the braking state of the foot brake by the operation of the electric actuator, the control unit controls the operation of the electric actuator and switches the foot brake from the braking state to the released state.

According to this configuration, in an emergency stop state in which the electric actuator switches the foot brake to the braking state under the control of the control unit, the administrator or the like can get into the driver unit and operate the operation tool to release the emergency stop state of the work vehicle at any time.

This enables the administrator who has gotten into the driver unit to manually drive the work vehicle, and the work vehicle can be moved to a safe place or a repair shop by manual driving.

In a third characteristic configuration,

if the autonomous drive mode is deselected when the foot brake is to be switched to the braking state and if the autonomous drive mode is selected by the mode selector after the deselection, the control unit determines whether or not an error has occurred inside the vehicle on the basis of detection information from the vehicle state detection device and permits a transition to the autonomous drive mode when it is determined that no errors have occurred inside the vehicle.

According to this configuration, in an emergency stop state of the work vehicle under the control of the control unit, even when the emergency stop under the control of the control unit is released, the work vehicle will not be able to autonomously drive until the control unit determines that there is no error inside the vehicle.

This makes it possible to prevent the automatic driving of the work vehicle while an error continues inside the vehicle.

A fourth characteristic configuration includes:

an electronically controlled engine,

wherein, if the control unit controls the operation of the electric actuator and the foot brake is switched from the released state to the braking state, the control unit automatically stops the engine.

According to this configuration, in the case where the work vehicle includes a work device driven by power from an engine, the work vehicle can be urgently stopped and the work device can be stopped under the control of the control unit.

In this way, the emergency stop of the work vehicle can be more preferably performed along with the stop of the work device.

In a fifth characteristic configuration,

if the operation of the electric actuator switches the foot brake to the braking state, and if power is turned on again by turning on a key switch provided in the driver unit after the power has been turned off by turning off the key switch in a state in which the engine is automatically stopped, the control unit permits activation of the engine and switches the foot brake form the braking state to the released state by controlling the operation of the actuator.

According to this configuration, in an emergency stop state of the work vehicle under the control of the control unit, the emergency stop state of the work vehicle can be released and the engine can be activated simply by the administrator or the like getting into the driver unit and operating the key switch.

As a result, the work vehicle can be more readily switched to a state in which it can be manually driven, and the work vehicle can be moved to a safe place or a repair shop more quickly.

