Steering assistance device, steering assistance program, and steering assistance method

Abstract

The present invention comprises: an intention estimation unit (103) that estimates, with three or more levels of accuracy, the steering intention of steering being performed by a driver in order to change lanes; and an intervention degree determination unit (105) which, for higher accuracies of the steering intention estimated by the intention estimation unit (103), determines a higher value for the degree of intervention of a steering assistance system (10) mounted in a vehicle being driven by the driver. The degree of intervention becomes relatively low when the accuracy of the steering intention is relatively low. Accordingly, it is possible to prevent the steering assistance system from excessively intervening in steering and giving the driver an unnatural feeling of manipulation from a time point when the steering intention is unclear. The degree of intervention becomes relatively high when the accuracy of the steering intention is relatively high. Accordingly, when the steering intention becomes clear, the degree of intervention of the steering assistance system in the steering becomes high, and the steering assistance system can assist the steering of the driver.

Description

Steering assistance device, steering assistance program, and steering assistance method Cross-reference to related applications

[0001] This application is based on Japanese Patent Application No. 2025-009831 filed in Japan on January 23, 2025, and the contents of the base application are incorporated herein by reference in their entirety.

[0002] It relates to a steering assistance device, a steering assistance program, and a steering assistance method for assisting the steering of a vehicle.

[0003] The driving assistance device disclosed in Patent Document 1 determines whether the host vehicle intends to turn right or left. And when it is determined that the host vehicle intends to turn right or left, and the host vehicle is taking a behavior that may cause the driver of the following vehicle to misrecognize that the host vehicle will not turn right or left, the driving assistance level is set to a high assistance level. The description of the prior art document is incorporated herein by reference as an explanation of the technical elements in this specification.

[0004] Japanese Unexamined Patent Application Publication No. 2019-121300

[0005] The driving assistance device disclosed in Patent Document 1 determines whether the driver intends to turn right or left, for example, based on the position of the direction indicator. Immediately after moving the direction indicator up and down, the driver often does not start a steering operation for turning right or left. That is, immediately after moving the direction indicator up and down, the driver's intention to change lanes is often not clear. If the steering assistance system intervenes significantly in steering from the time when the driver's intention to change lanes is not clear, it will give the driver an unnatural operation feeling.

[0006] The present disclosure has been made based on this situation, and an object thereof is to provide a steering assistance device, a steering assistance program, and a steering assistance method capable of appropriately intervening in steering according to the driver's intention to change lanes.

[0007] The above objectives are achieved by combinations of features described in the independent claims, and the subordinate claims provide further advantageous specific examples. The reference numerals in parentheses in the claims indicate a correspondence with specific embodiments described later as one aspect, and do not limit the scope of the disclosed technical information.

[0008] One disclosure relating to a steering assistance device for achieving the above objective is a steering assistance device comprising: an intention estimation unit that estimates the driver's intention to steer in order to change lanes with an accuracy of three or more levels; and an intervention degree determination unit that determines a higher degree of intervention by the steering assistance system installed in the vehicle being driven by the driver, the higher the accuracy of the steering intention estimated by the intention estimation unit.

[0009] One disclosure relating to a steering assistance program for achieving the above objective is a steering assistance program that causes at least one processor to function as: an intention estimation unit that estimates the driver's intention to steer in order to change lanes with an accuracy of three or more levels; and an intervention degree determination unit that determines the degree of intervention of the steering assistance system installed in the vehicle being driven by the driver to be a higher value the higher the accuracy of the steering intention estimated by the intention estimation unit.

[0010] One disclosure relating to a steering assistance method for achieving the above objective is a steering assistance method performed by at least one of a processor and a circuit, wherein the method estimates the driver's steering intention to change lanes with three or more levels of accuracy, and determines a higher level of intervention by the steering assistance system installed in the vehicle driven by the driver, the higher the accuracy of the estimated steering intention.

[0011] These steering assistance devices, steering assistance programs, and steering assistance methods intervene to a relatively low degree when the driver's intention to change lanes is relatively low. Therefore, it is possible to prevent the steering assistance system from intervening too much in the steering when the driver's intention to change lanes is unclear, thus preventing the driver from experiencing an unnatural feeling of operation. On the other hand, when the driver's intention to change lanes is relatively high, the degree of intervention is relatively high. Therefore, when the driver's intention to change lanes becomes clear, the degree to which the steering assistance system intervenes in the steering increases, and the steering can be assisted by the driver. In this way, the steering assistance system can perform appropriate steering intervention according to the driver's intention to change lanes.

[0012] A diagram showing the configuration of the steering assistance system. A diagram illustrating the relationship between steering intention and intervention level α. A diagram showing a different example of the relationship between steering intention and intervention level α from Figure 2.

[0013] The embodiments will be described below with reference to the drawings. Figure 1 is a diagram showing the configuration of the steering support system 10 of this embodiment. The steering support system 10 is installed in a vehicle driven by a driver and is a system that assists the driver in steering. The vehicle on which the steering support system 10 is installed is a vehicle that employs a steer-by-wire system. In a steer-by-wire system, the steering wheel and the steering angle control unit 20 are mechanically separated, and the steering wheel and the steering angle control unit 20 are electrically connected. Even if the steering angle control unit 20 changes the steering angle of the steering wheel, the change in the steering angle of the steering wheel is not reflected in the steering wheel. The steering support system 10 comprises the steering angle control unit 20, the steering angle sensor 30, and the steering support ECU 100 which functions as a steering support device.

[0014] The steering angle control unit 20 controls the steering angle. The steering angle is the angle at which the steering wheel turns. The steering angle control unit 20 includes a mechanical mechanism that changes the angle at which the steering wheel turns, a motor that operates the mechanical mechanism, and a steering angle control device that controls the motor. The steering angle control device acquires the control steering angle, which is an instructed value, and controls the motor so that the steering angle becomes that control steering angle. The steering angle sensor 30 detects the rotation angle (hereinafter referred to as the steering angle) θ of the steering wheel. The steering angle θ is sometimes called the steering angle.

[0015] The steering assistance ECU 100 is a computer and its hardware configuration includes a processor, RAM, and non-volatile memory. The non-volatile memory stores the steering assistance program executed by the processor. By executing the steering assistance program, the processor functions as the driver operation steering angle determination unit 101, target steering angle determination unit 102, intention estimation unit 103, and mixing unit 104 shown in Figure 1. Furthermore, the execution of the steering assistance program by the processor executes the steering assistance method.

[0016] The driver operation steering angle determination unit 101 sequentially acquires the steering angle θ that the steering angle sensor 30 sequentially detects. Based on the steering angle θ, the driver operation steering angle determination unit 101 sequentially determines the driver operation steering angle Udr, which is the steering angle of the steering wheel determined by the operation input by the driver to the steering wheel. For example, the driver operation steering angle determination unit 101 sequentially determines the driver operation steering angle Udr from a pre-set relationship in which the driver operation steering angle Udr is determined from the steering angle θ and the steering angle θ acquired from the steering angle sensor 30. The pre-set relationship is, for example, the same as the relationship between the steering angle θ and the steering angle when the steering wheel and the steering wheel are mechanically connected.

[0017] The target steering angle determination unit 102 sequentially determines the target steering angle Uref for the vehicle to travel along the target trajectory. The target steering angle Uref is the target value of the steering angle. The target trajectory is the trajectory that follows the road shape when the vehicle does not change lanes, and the trajectory that follows the road while changing lanes when the vehicle does change lanes. Alternatively, the target steering angle determination unit 102 may not calculate the target trajectory, and another ECU may calculate the target trajectory, and the target steering angle determination unit 102 may acquire the target trajectory calculated by the other ECU.

[0018] The target steering angle determination unit 102 acquires road shape information and vehicle driving information. The road shape information is information about the road shape necessary to calculate the target steering angle Uref. The road shape information includes the curvature of the road. In addition, the road shape information may also include information other than the curvature of the road, such as the road width and lane width. The vehicle driving information is information about the vehicle's driving state necessary to determine the target steering angle Uref. The vehicle driving information may also include the vehicle's speed, vehicle position, and vehicle orientation. The target steering angle determination unit 102 acquires information from the driver operation steering angle determination unit 101 in order to determine whether the target trajectory is a trajectory for lane changes. The information that the target steering angle determination unit 102 acquires from the driver operation steering angle determination unit 101 is the steering angle θ. In addition, the target steering angle determination unit 102 may acquire the driver operation steering angle Udr instead of the steering angle θ.

[0019] The intention estimation unit 103 sequentially estimates the driver's steering intention to change lanes. The steering intention means whether the driver will steer to change lanes at the present time or in the very near future. The intention estimation unit 103 estimates the lane change intention by acquiring various information. The information that the intention estimation unit 103 acquires to estimate the steering intention is, for example, at least one of the following: steering angle θ, surrounding information, and in-vehicle information. Surrounding information is information about the area around the vehicle and may include the road shape information mentioned above. Traffic information may also be included in the surrounding information. In-vehicle information is information about the inside of the vehicle that changes in response to steering. For example, one piece of in-vehicle information is information indicating the operating state of the turn signals. The amount of operation of the accelerator pedal and / or the amount of operation of the brake pedal may be included in the in-vehicle information. Note that θ may also be included in the in-vehicle information. In addition, information indicating the driver's line of sight may be included in the in-vehicle information.

[0020] The intention estimation unit 103 sequentially estimates steering intention using information acquired to estimate steering intention and a pre-set relationship that allows the steering intention to be determined from that information. The above relationship can be created by machine learning. In machine learning, the information acquired to estimate steering intention is associated with whether the driver actually performed steering. Through learning, it is possible to determine what specific values ​​of information acquired to estimate steering intention indicate what probability the driver will perform steering. By dividing this probability into multiple categories, a relationship can be created that allows the steering intention to be estimated in multiple stages from the information acquired to estimate steering intention. In this embodiment, the steering intention is estimated with three levels of accuracy: unknown intention, intention under confirmation, and confirmed intention. Of these three levels of accuracy, unknown intention has the lowest accuracy, and confirmed intention has the highest accuracy.

[0021] The mixing unit 104 mixes the driver-operated steering angle Udr and the target steering angle Uref to determine the control steering angle Umix, and outputs this control steering angle Umix to the steering angle control unit 20. The steering angle control unit 20 controls the steering angle so that it matches the control steering angle Umix.

[0022] As shown in Figure 1, the mixing unit 104 includes an intervention degree determination unit 105 and a control rudder angle determination unit 106. The intervention degree determination unit 105 determines the intervention degree α from the steering intention estimated by the intention estimation unit 103. The intervention degree α is a value that indicates the extent to which the steering support system 10 intervenes in steering control. Specifically, the intervention degree α is a variable used in the control rudder angle determination unit 106.

[0023] The intervention level determination unit 105 determines the intervention level α to be higher the higher the accuracy of the steering intention. The relationship between steering intention and intervention level α is predetermined. Figure 2 illustrates the relationship between steering intention and intervention level α. The relationship shown in Figure 2 is such that the intervention level α increases in stages as the accuracy of the steering intention increases. In Figure 2, the intervention level α is determined to be one of three levels: 0.1, 0.2, or 0.4. In this case, 0.1 is the lower limit of intervention level α, 0.2 is the median value of intervention level α, and 0.4 is the upper limit of intervention level α. Note that the lower limit of intervention level α does not have to be 0.1, and the upper limit does not have to be 0.4. The median value does not have to be 0.2 either; it can be anywhere between the lower limit and the upper limit.

[0024] The control steering angle determination unit 106 determines the control steering angle Umix by dividing the driver's steering angle Udr and the target steering angle Uref using an internal division ratio determined based on the intervention degree α determined by the intervention degree determination unit 105. This control method, in which the control steering angle Umix is ​​determined without sharing the steering end (steering wheel) with the system, is called mixing input shared control. The control steering angle Umix is ​​calculated from Equation 1. The control steering angle determination unit 106 outputs the determined control steering angle Umix to the steering angle control unit 20.

[0025] In the embodiment described above, when the accuracy of the driver's steering intention is relatively low, the intervention degree α becomes relatively low. Therefore, it is possible to prevent the steering support system 10 from intervening too much in steering when the driver's steering intention is unclear, thereby giving the driver an unnatural feeling of operation. On the other hand, when the accuracy of the driver's steering intention is relatively high, the intervention degree α becomes relatively high. Therefore, when the driver's steering intention becomes clear, the degree to which the steering support system 10 intervenes in steering increases, and the steering can be supported by the driver. In this way, the steering support system 10 can perform appropriate steering intervention in accordance with the driver's steering intention.

[0026] Let's explain with a specific example. When changing lanes while driving on a highway, the driver may be timing the appropriate steering operation for the lane change from the moment they activate the turn signal and start flashing the turn signal light until they actually begin steering to change lanes. In this situation, the intention estimation unit 103 can estimate that the driver is still confirming their steering intention. As a result, the intervention level α is also determined to be a low value, which prevents the steering assistance system 10 from intervening too much in the steering before the driver's steering intention is clear, thus preventing the driver from experiencing an unnatural feeling of operation.

[0027] Then, when the driver determines that the timing is appropriate and begins steering, the intention estimation unit 103 estimates the steering intention as confirmed. As a result, the control steering angle determination unit 106 increases the intervention level α to its upper limit, enabling smooth lane changes.

[0028] Let's explain another specific example. When changing lanes to an adjacent lane in an urban area, even if the driver operates the turn signal and the turn signal lights up, the driver may not steer depending on the position and speed of other vehicles traveling in the adjacent lane. In this case as well, the intention estimation unit 103 can estimate that the steering intention is still being confirmed. As a result, the intervention degree α is also determined to be a low value. Then, if the intention estimation unit 103 estimates that the intention is confirmed based on the driver's gaze and steering operation, the control steering angle determination unit 106 increases the intervention degree α to its upper limit, enabling a smooth lane change.

[0029] To determine the intervention level α, the steering support ECU 100 sequentially determines the driver-operated steering angle Udr based on the steering angle θ, and also sequentially determines the target steering angle Uref for driving along the target trajectory. Then, based on the intervention level α, the steering support ECU 100 determines the internal division value obtained by internally dividing the driver-operated steering angle Udr and the target steering angle Uref as the control steering angle Umix. In this way, it is possible to determine a control steering angle Umix that enables steering intervention in accordance with the driver's steering intention.

[0030] The steering angle determination unit 106 can set the intervention level α to three levels, and accordingly, the intention estimation unit 103 determines the steering intention to be one of three levels: unknown intention, intention under confirmation, or confirmed intention. In this way, the steering support system 10 can intervene in steering with three levels of intervention α corresponding to the steering intention.

[0031] The intervention level α determined by the intervention level determination unit 105 is set to an upper limit of 0.4, which is less than 0.5. Therefore, even if the steering intention is estimated to be confirmed, the intervention level α will not exceed 0.4. When the intervention level is less than 0.5, it is a driver-initiated steering operation. Accordingly, according to this embodiment, appropriate steering intervention can be performed in accordance with the driver's steering intention, within a range that allows the driver-initiated steering operation to be maintained.

[0032] The intervention level α determined by the intervention level determination unit 105 has a lower limit of 0.1. Because the lower limit is set to 0.1, even if the steering intention is estimated to be unclear, the intervention level α will not fall below 0.1. As a result, even when the driver's steering intention is unclear, the steering support system 10 provides some steering assistance, reducing the driver's workload for lane keeping.

[0033] Although embodiments have been described above, the disclosed technology is not limited to the embodiments described above. The following modifications are also included within the scope of disclosure, and further modifications can be made in various ways without departing from the gist of the invention. In the following description, elements having the same reference numerals as those used up to that point are the same as the elements with the same reference numerals in the previous embodiments, unless otherwise specified. Also, if only a part of the configuration is described, the previously described embodiments can be applied to the other parts of the configuration.

[0034] <Modification 1> In the embodiment, the intervention level α determined by the intervention level determination unit 105 was set to a lower limit of 0.1 and an upper limit of 0.4. However, the intervention level α may be determined within a range from 0 to 1.

[0035] <Modification 2> Steering intention may be estimated as a continuous value, such as a percentage. In this case, steering intention can be determined in three or more stages. As shown in Figure 3, the relationship between steering intention and intervention degree α may have an interval in which the intervention degree α increases continuously from a lower limit to an upper limit as the accuracy of the steering intention increases. In Figure 3, the lower limit and upper limit of intervention degree α are 0.1 and 0.4, respectively, as in Figure 2. However, as in Figure 2, the lower limit of intervention degree α does not have to be 0.1, and the upper limit does not have to be 0.4.

[0036] <Modification 3> The steering assist ECU 100 only needs to have at least one of a processor and a circuit as its hardware configuration. Therefore, the steering assist ECU 100 is not limited to a configuration with a processor, and may have a configuration without a processor and with hardware circuits other than a processor, or it may have a configuration with a processor and hardware circuits other than a processor.

[0037] (Disclosure of Technical Ideas) This specification discloses several technical ideas as described in the following paragraphs. Some paragraphs may be written in a multiple dependent form, where subsequent paragraphs optionally refer to preceding paragraphs. Furthermore, some paragraphs may be written in a multiple dependent form, where they refer to other multiple dependent forms. These paragraphs written in multiple dependent forms define several technical ideas.

[0038] (Technical Concept 1) A steering assist device comprising: an intention estimation unit (103) that estimates the driver's intention to steer in order to change lanes with an accuracy of three or more levels; and an intervention degree determination unit (105) that determines the degree of intervention by the steering assist system (10) installed in the vehicle driven by the driver to be a higher value the higher the accuracy of the steering intention estimated by the intention estimation unit.

[0039] (Technical Concept 2) A steering support device according to Technical Concept 1, comprising: a driver operation steering angle determination unit (101) that sequentially determines a driver operation steering angle (Udr), which is the steering angle of the steering wheel determined by the operation input by the driver based on the steering angle; a target steering angle determination unit (102) that sequentially determines a target steering angle (Uref) for the vehicle to travel along a target trajectory; and a control steering angle determination unit (106) that determines an internal division value obtained by internally dividing the driver operation steering angle and the target steering angle based on the degree of intervention as a control steering angle for controlling the steering wheel.

[0040] (Technical Concept 3) The steering support device according to Technical Concept 1 or 2, wherein the intention estimation unit determines the steering intention to be one of three stages: intention unknown, intention under confirmation, or intention confirmed; and the intervention level determination unit determines the intervention level to the lower limit if the steering intention is unknown, to the upper limit if the steering intention is confirmed, and to the intermediate value if the steering intention is under confirmation.

[0041] (Technical idea 4) The upper limit value of the intervention degree is a value smaller than 0.5, and the steering assistance device according to any one of Technical ideas 1 to 3.

[0042] (Technical idea 5) A lower limit value greater than 0 is set for the intervention degree, and the steering assistance device according to any one of Technical ideas 1 to 4.

[0043] (Technical idea 6) A tangible computer-readable recording medium non-transitionally recording a steering assistance program for causing at least one processor to estimate a steering intention of a driver to perform steering for lane change with an accuracy of three or more levels, and determining a higher intervention degree for the steering assistance system (10) mounted on the vehicle driven by the driver to intervene in steering as the estimated accuracy of the steering intention is higher.

[0044] In the present disclosure or claims, the term "processor" is a processor as single or multiple hardware, configured to execute processing defined by the computer program code (i.e., one or more instructions of the computer program) included in the computer program by reading the computer program code each time. In other words, the "processor" is a hardware device that executes one or more programmed processes. Therefore, the computer program code can also be said to be software that can define the processing of the processor according to its content. The "processor" can be a general-purpose or special-purpose processor, and can be, for example, a CPU, a microprocessor, a GPU, and a DFP (Data Flow Processor), etc., but is not limited thereto.

[0045] In this disclosure or claims, the term “memory” refers to one or more hardware memories that are non-transitional tangible recording media configured to record computer program code and / or data in a manner accessible by a processor. “Memory” can be implemented by memory technologies such as SRAM, SDRAM, non-volatile / flash type memory, or other types of memory. The computer program code that constitutes the program is recorded in memory and executed by the processor, thereby enabling the processor to perform the various functions described above.

[0046] In this disclosure or claims, the term “circuit” refers to a logic circuit as one or more pieces of hardware, configured to perform specific processing defined by a pre-designed circuit configuration. In other words (and, in contrast to “processor”), “circuit” in this disclosure or claims refers to a hardware device that performs specific processing based on a circuit configuration, rather than processing defined by software such as the computer program code described above. For example, “circuit” may include custom ICs such as ASICs (Application Specific Integrated Circuits) and FPGAs (Field Programmable Gate Arrays) designed with Hardware Description Language (HDL). That is, “circuit” in this disclosure or claims includes all hardware circuits except for the processor described above, which performs processing by reading computer program code.

[0047] Furthermore, within the scope of this disclosure or claims, the expression "at least one processor and circuit" should be interpreted as a disjunctive (logical OR) and not as at least one processor and at least one circuit.

Claims

1. A steering assistance device comprising: an intention estimation unit (103) that estimates the driver's intention to steer in order to change lanes with an accuracy of three or more levels; and an intervention degree determination unit (105) that determines a higher degree of intervention by the steering assistance system (10) installed in the vehicle driven by the driver, the higher the accuracy of the steering intention estimated by the intention estimation unit.

2. A steering support device according to claim 1, comprising: a driver operation steering angle determination unit (101) that sequentially determines a driver operation steering angle (Udr), which is the steering angle of the steering wheel determined by the operation input by the driver, based on the steering angle; a target steering angle determination unit (102) that sequentially determines a target steering angle (Uref) for the vehicle to travel along a target trajectory; and a control steering angle determination unit (106) that determines an internal division value obtained by internally dividing the driver operation steering angle and the target steering angle based on the degree of intervention as a control steering angle for controlling the steering wheel.

3. The steering support device according to claim 1 or 2, wherein the intention estimation unit determines the steering intention to be one of three stages: intention unknown, intention under confirmation, or intention confirmed; and the intervention level determination unit determines the intervention level to the lower limit if the steering intention is unknown, determines the intervention level to the upper limit if the steering intention is confirmed, and determines the intervention level to the intermediate value if the steering intention is under confirmation.

4. The steering support device according to claim 1 or 2, wherein the upper limit of the intervention level is less than 0.

5.

5. The steering assistance device according to claim 1 or 2, wherein a lower limit greater than 0 is set for the degree of intervention.

6. A steering assistance program that causes at least one processor to function as: an intention estimation unit (103) that estimates the driver's intention to steer in order to change lanes with three or more levels of accuracy; and an intervention level determination unit (105) that determines a higher level of intervention by the steering assistance system (10) installed in the vehicle driven by the driver, the higher the accuracy of the steering intention estimated by the intention estimation unit.

7. A steering assistance method performed by at least one of a processor and a circuit, wherein the steering intention of a driver to steer for a lane change is estimated with three or more levels of accuracy, and the higher the accuracy of the estimated steering intention, the higher the level of intervention of the steering assistance system (10) installed in the vehicle driven by the driver.

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