US-12617415-B2 - Hands-free state determination device for vehicle

US12617415B2US 12617415 B2US12617415 B2US 12617415B2US-12617415-B2

Abstract

A hands-free state determination device including: a torque imparting device configured to apply control torque to a steering transmission system between a steering wheel and a steered wheel; a steering torque sensor provided in the steering transmission system between the steering wheel and the torque imparting device; and a control unit configured to determine that the driver is in a hands-free state in which the steering wheel is not held when the steering torque detected by the steering torque sensor is within a first predetermined range, wherein the control unit performs variable setting of the first predetermined range based on the steering torque detected by the steering torque sensor in a situation where it is determined that the torque is not input to the steering torque sensor.

Inventors

Takanori Tanaka

Assignees

TOYOTA JIDOSHA KABUSHIKI KAISHA

Dates

Publication Date: 20260505
Application Date: 20240430
Priority Date: 20230703

Claims (5)

1 . A hands-free state determination device for a vehicle, the hands-free state determination device comprising: a torque imparting device that is configured to impart a control torque to a steering transmission system between a steering wheel and a steered wheel; a steering torque sensor that is provided in the steering transmission system, between the steering wheel and the torque imparting device; and a control unit that is configured to determine that a driver is in a hands-free state, in which the driver is not gripping the steering wheel, when a steering torque detected by the steering torque sensor is within a first predetermined range, wherein the control unit is configured to perform a variable setting of the first predetermined range, based on the steering torque detected by the steering torque sensor, in a situation in which determination is made that no torque is being input to the steering torque sensor; wherein the control unit is configured to determine that no torque is being input to the steering torque sensor from the steered wheel side, when determining that the vehicle is traveling straight, and that the vehicle is traveling in a middle of a lane, and that a road surface is not laterally inclined.
2 . The hands-free state determination device according to claim 1 , wherein: the first predetermined range is a range between a value obtained by subtracting a predetermined value from a reference torque and a value obtained by adding the predetermined value to the reference torque; and the control unit is configured to perform the variable setting of the first predetermined range by setting the steering torque detected by the steering torque sensor as the reference torque in the situation in which determination is made that no torque is being input to the steering torque sensor.
3 . The hands-free state determination device according to claim 1 , wherein the control unit is configured to determine that no torque is being input to the steering torque sensor from the steered wheel side, when determining that the vehicle is in a state of traveling straight, and that a magnitude of a lateral force acting on the vehicle is no greater than a reference value for lateral force determination, and that a magnitude of the control torque is no greater than a reference value for control torque determination.
4 . The hands-free state determination device according to claim 1 , wherein the control unit is configured to determine that no torque is being input to the steering torque sensor from the steering wheel side, when the steering torque detected by the steering torque sensor is within a second predetermined range that is greater than the first predetermined range, in a situation in which no torque is being input to the steering torque sensor from the steered wheel side.
5 . A hands-free state determination device for a vehicle, the hands-free state determination device comprising: a torque imparting device that is configured to impart a control torque to a steering transmission system between a steering wheel and a steered wheel; a steering torque sensor that is provided in the steering transmission system, between the steering wheel and the torque imparting device; and a control unit that is configured to determine that a driver is in a hands free state, in which the driver is not gripping the steering wheel, when a steering torque detected by the steering torque sensor is within; at predetermined range, wherein the control unit is configured to perform a variable setting of the first predetermined range, based on the steering torque detected by the steering torque sensor in a situation in which determination is made that no torque is being input to the steering torque sensor; wherein the control unit is configured to determine that no torque is being input to the steering torque sensor from the steering wheel side, when the steering torque detected by the steering torque sensor is within a second predetermined range that is greater than the first predetermined range, in a situation in which no torque is being input to the steering torque sensor from the steered wheel side.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims priority to Japanese Patent Application No. 2023-109218 filed on Jul. 3, 2023, incorporated herein by reference in its entirety. BACKGROUND 1. Technical Field The disclosure relates to a hands-free state determination device for a vehicle such as an automobile. 2. Description of Related Art Well-known examples of an automated driving device for a vehicle such as an automobile include a steering assisting device such as a lane keeping assisting device that controls a lateral-direction position of the vehicle with respect to a lane by automated steering, a lane departure suppressing device, a lane change assisting device, and so forth. Steering assistance by the steering assisting device may be performed on the assumption that a driver is gripping a steering wheel. When the driver is not gripping the steering wheel, a situation in which the magnitude of steering torque is small continues, and accordingly, performing determination of whether the driver is in a hands-free state of not holding the steering wheel, based on the steering torque detected by a steering torque sensor, is known. For example, Japanese Unexamined Patent Application Publication No. 2020-117025 (JP 2020-117025 A) describes hands-free state determination technology in which, when a determination that the magnitude of the steering torque detected by the steering torque sensor is less than a reference value is consecutively made a predetermined number of times, determination is made that the hands of the driver are free from the steering wheel. According to the hands-free state determination technology, the hands-free state of the driver can be detected without requiring an expensive sensor such as a touch sensor. SUMMARY When the vehicle is in a straight traveling state and neither automated steering nor steering by the driver is being performed, no torque acts on the steering torque sensor, and accordingly the steering torque detected by the steering torque sensor is 0. However, when there is error in assembly of the steering device or the steering torque sensor, output error may occur in which the steering torque detected by the steering torque sensor is a value other than 0, even when the vehicle is in the straight traveling state and neither automated steering nor steering by the driver are being performed. Further, output error of the steering torque sensor may occur when there is misalignment in wheel alignment of steered wheels, right-left weight balance of the vehicle, and so forth. When output error of the steering torque sensor occurs due to the above-described factors, the magnitude of the steering torque detected by the steering torque sensor may become equal to or greater than the reference value due to the output error, and the driver may be erroneously determined not to be in the hands-free state, despite the driver being in the hands-free state. The disclosure provides a hands-free state determination device that is improved so as to be capable of reducing a likelihood of a determination as to whether the driver is in a hands-free state being an erroneous determination, even when output error of the steering torque sensor occurs due to a factor such as assembly error of the steering device. According to the disclosure, provided is a hands-free state determination device for a vehicle, including a torque imparting device that is configured to impart a control torque to a steering transmission system between a steering wheel and a steered wheel, a steering torque sensor that is provided in the steering transmission system, between the steering wheel and the torque imparting device, and a control unit that is configured to determine that a driver is in a hands-free state, in which the driver is not gripping the steering wheel, when a steering torque detected by the steering torque sensor is within a first predetermined range. The control unit is configured to perform a variable setting of the first predetermined range, based on the steering torque detected by the steering torque sensor, in a situation in which determination is made that no torque is being input to the steering torque sensor. According to the above configuration, the first predetermined range is variably set based on the steering torque detected by the steering torque sensor in the situation in which determination is made that no torque is being input to the steering torque sensor. Steering torque that is detected by the steering torque sensor in the situation in which determination is made that no torque is being input to the steering torque sensor is output error of the steering torque sensor, due to a factor such as assembly error of the steering device or the like. Accordingly, the first predetermined range can be variably set based on output error of the steering torque sensor. Thus, in a situation in which output error of the steering torque sensor is occurring due to a factor such as assembly e