Steering assistance device, steering assistance program, and steering assistance method
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- DENSO CORP
- Filing Date
- 2026-01-07
- Publication Date
- 2026-07-30
Smart Images
Figure JP2026000282_30072026_PF_FP_ABST
Abstract
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. 2025-009830 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] Patent Document 1 discloses steering entropy. Steering entropy is a value representing the smoothness of a driver's steering control by entropy. Steering entropy is a value correlated with driver load. Non-Patent Document 1 discloses a real-time steering entropy method for determining steering entropy in real time. In the real-time steering entropy method, relative steering entropy indicating the driver's recent steering characteristics with respect to the driver's innate steering characteristics is sequentially calculated. 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. 2023-59751
[0005] Takayuki Kondo, et al., "Development of Real-Time Steering Entropy Method for Quantifying Driver Load", Transactions of the Japan Society of Automotive Engineers, January 2015, Vol. 46, No. 1, p. 167-172
[0006] As described above, research on relative steering entropy exists. However, a specific method for assisting a driver's steering operation using relative steering entropy has not been developed. Therefore, the steering assistance system cannot perform appropriate steering intervention according to the driver's driving load.
[0007] 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 performing appropriate steering intervention according to the driver's driving load by a steering assistance system.
[0008] 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.
[0009] One disclosure relating to a steering support device for achieving the above objective is a steering support device comprising: an entropy determination unit that sequentially acquires the steering angle and, based on the steering angle, sequentially determines a relative steering entropy, which is a value that expresses the smoothness of the driver's steering control in entropy and indicates the driver's most recent steering characteristics relative to the driver's normal steering characteristics; and an intervention degree determination unit that determines a higher value for the degree to which the steering support system installed in the vehicle being driven intervenes in the steering control as the relative steering entropy indicates a state of high driver load.
[0010] 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 entropy determination unit that sequentially acquires the steering angle and, based on the steering angle, sequentially determines a relative steering entropy, which is a value that expresses the smoothness of the driver's steering control in entropy and indicates the driver's most recent steering characteristics relative to the driver's normal steering characteristics; and an intervention degree determination unit that determines a higher value for the degree to which the steering assistance system installed in the vehicle being driven intervenes in the steering control as the relative steering entropy indicates a high load on the driver.
[0011] 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 steering angle is successively acquired, and based on the steering angle, a relative steering entropy is successively determined, which is a value that expresses the smoothness of the driver's steering control in entropy and indicates the driver's most recent steering characteristics relative to the driver's normal steering characteristics, and the degree of intervention of the steering assistance system installed in the vehicle being driven by the driver is determined to be a higher value as the relative steering entropy indicates a state of high driver load.
[0012] These steering assistance devices, steering assistance programs, and steering assistance methods determine the degree of intervention by the steering assistance system in steering control to be higher as the relative steering entropy indicates a higher driver load. In this way, the steering assistance system can perform appropriate steering intervention according to the driver's driving load.
[0013] A diagram showing the configuration of the steering assistance system. A diagram explaining the calculation process of relative steering entropy. A diagram showing the process of S20 in Figure 2 in detail. A diagram illustrating the prediction error distribution. A diagram illustrating the relationship between relative steering entropy RHp and intervention degree α. A diagram showing a different example of the relationship between relative steering entropy RHp and intervention degree α from Figure 5. A diagram showing the time change of relative steering entropy RHp and the time change of intervention degree α.
[0014] 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.
[0015] 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.
[0016] The steering assistance ECU 100 comprises a processor, RAM, and non-volatile memory as its hardware configuration. 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, the target steering angle determination unit 102, and the mixing unit 103 shown in Figure 1. Furthermore, the execution of the steering assistance program by the processor executes the steering assistance method.
[0017] The driver-operated steering angle determination unit 101 sequentially acquires the steering angle θ that the steering angle sensor 30 sequentially detects. Since the steering wheel is operated by the driver, the steering angle θ reflects the angle of the steering wheel intended by the driver. Therefore, the driver-operated steering angle determination unit 101 sequentially determines the driver-operated steering angle Udr, which is the steering angle of the steering wheel intended by the driver, based on the steering angle θ. For example, the driver-operated steering angle determination unit 101 sequentially determines the driver-operated steering angle Udr from a pre-set relationship in which the driver-operated 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.
[0018] 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.
[0019] 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.
[0020] The mixing unit 103 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.
[0021] As shown in Figure 1, the mixing unit 103 includes an entropy determination unit 104, an intervention degree determination unit 105, and a control steering angle determination unit 106. The entropy determination unit 104 sequentially determines the relative steering entropy RHp. Relative steering entropy RHp will be explained below. Steering entropy Hp is a value that expresses the smoothness of the driver's steering control in terms of entropy. Furthermore, since the smoothness of the driver's steering control is correlated with the driving load, steering entropy Hp represents the driving load. Relative steering entropy RHp is a value that expresses steering entropy Hp as a relative value, and indicates the driver's most recent steering characteristics relative to the driver's normal steering characteristics.
[0022] The calculation process for relative steering entropy RHp will be explained in detail using Figure 2. In S10, the steering angle prediction error PE is calculated. Specifically, the steering angle prediction error PE is calculated as follows. First, the average value of the steering angle θ acquired sequentially over a predetermined number of past times is calculated by dividing it into groups of multiple times. For example, the steering angle θ of the past 9 times is divided into groups of 3 times and the average value is calculated.
[0023] Let's explain this in detail by defining θ0 as the latest steering angle θ, θ1 as the steering angle θ obtained one step ago, θ2 as the steering angle θ obtained two steps ago, and so on. The average values of the past nine steering angles θ, divided into groups of three, are θa1 (the average of θ1, θ2, θ3), θa2 (the average of θ4, θ5, θ6), and θa3 (the average of θ7, θ8, θ9). A second-order Taylor expansion is performed on these three average values to calculate the current predicted steering angle θp. The predicted steering angle θp can be calculated using Equation 1. The steering angle prediction error PE can then be calculated as θ0 - θp.
[0024] In S20, the prediction error distribution is updated. The prediction error distribution is a probability density distribution obtained by distributing the steering angle prediction error PE into multiple (for example, nine) bins. The process in S20 is shown in detail in Figure 3. In S21, the probability density q(i) of each bin in the previous prediction error distribution is read. i represents each bin. Figure 4 shows an example of the prediction error distribution.
[0025] In S22, it is determined which bin of the prediction error distribution read in S21 corresponds to the steering angle prediction error PE calculated in S10. In S23, the probability density q of each bin is recursively updated. ql, which represents the distribution of the driver's inherent steering characteristics, and qs, which represents the distribution of the most recent steering characteristics influenced by the driver state, are calculated using the following formulas. For bins where the steering angle prediction error PE value is newly entered, formulas 2 and 3 apply; for other bins, formulas 4 and 5 apply.
[0026] In equations 2, 3, 4, and 5, Ns and Nl are the number of samples for each time interval, and are the product of the calculation period and the time interval. The calculation period is, for example, 50 ms, and the time interval for the distribution of the most recent steering characteristics is, for example, 90 seconds. The distribution of the driver's innate steering characteristics requires a longer time interval than the distribution of the most recent steering characteristics. The time interval for the distribution of the driver's innate steering characteristics is, for example, 2160 seconds. Note that the driver's innate steering characteristics can also be called the driver's normal steering characteristics.
[0027] In S24, the prediction error distribution updated in S23 is saved. After completing S24, the process proceeds to S30 in Figure 2. In S30, the absolute steering entropies Hpl and Hps are calculated. Specifically, the absolute steering entropies Hpl and Hps of the two prediction error distributions updated in S20 are calculated from equations 6 and 7 below. Hpl is the absolute steering entropy calculated from the driver's inherent steering characteristic distribution, and Hps is the absolute steering entropy calculated from the most recent steering characteristic distribution.
[0028] In S40, the relative steering entropy RHp is calculated. The relative steering entropy RHp is calculated using Equation 8, with the two prediction error distributions updated in S20 and the absolute entropies calculated in S30.
[0029] Let's return to the explanation in Figure 1. The intervention level determination unit 105 determines the intervention level α from the relative steering entropy RHp. The intervention level α is a value that indicates the degree to which the steering support system 10 intervenes in steering control. Specifically, the intervention level α is a variable used in the control steering angle determination unit 106. The intervention level determination unit 105 determines a higher value for the intervention level α as the relative steering entropy RHp indicates a higher driver's driving load. Note that a higher value for relative steering entropy RHp means a higher driver's driving load.
[0030] The relationship between relative steering entropy RHp and intervention level α is predetermined. For example, as shown in Figure 5, the relationship between relative steering entropy RHp and intervention level α is such that the intervention level α increases in steps as the relative steering entropy RHp increases, that is, as the driver load increases. In Figure 5, 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, and 0.4 is the upper limit of intervention level α. Note that the intervention level α may be determined to be one of two levels, or to be determined to be four or more levels. Also, 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.
[0031] Furthermore, as shown in Figure 6, the relationship between relative steering entropy RHp and intervention degree α may be such that, in the intervention degree change interval of relative steering entropy RHp, the intervention degree α continuously increases from the lower limit to the upper limit as the relative steering entropy RHp increases. The intervention degree change interval is from the intervention change start value RHp1 to the intervention change end value RHp2 shown in Figure 6. Also, in Figure 6, the lower limit and upper limit of intervention degree α are 0.1 and 0.4, respectively, as in Figure 5. Note that, as in Figure 5, 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.
[0032] 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 steering end (steering wheel) is not shared with the system and the control steering angle Umix is determined, is called mixed input shared control. The control steering angle Umix is calculated from equation 9.
[0033] The steering angle determination unit 106 may immediately output the steering angle control unit 20 the steering angle Umix obtained by substituting the intervention degree α determined by the intervention degree determination unit 105 into equation 9, regardless of the rate of change of the relative steering entropy RHp. However, in this embodiment, the faster the rate of change of the relative steering entropy RHp, the faster the α substituted into equation 9 is changed to the intervention degree α determined by the intervention degree determination unit 105. In other words, if the rate of change of the relative steering entropy RHp is slow, the α substituted into equation 9 is changed continuously or stepwise over time to the intervention degree α determined by the intervention degree determination unit 105. The fastest way to change the α substituted into equation 9 to the intervention degree α determined by the intervention degree determination unit 105 is to immediately set the α substituted into equation 9 to the intervention degree α determined by the intervention degree determination unit 105.
[0034] The value of α to be substituted into Equation 9 will be explained in detail using Figure 7. The upper part of Figure 7 shows the time change of the relative steering entropy RHp, and the lower part of Figure 7 shows the time change of α to be substituted into Equation 9. In the upper part of Figure 7, both the solid and dashed lines show that the relative steering entropy RHp increases from time t1 to time t2. The solid line shows that the relative steering entropy RHp rises to a higher value, so the rate of change of the relative steering entropy RHp is faster for the solid line. In reality, there is some change in the relative steering entropy RHp during time periods other than from time t1 to time t2. Figure 7 is a conceptual diagram and is presented in this way to make the explanation easier to understand.
[0035] The figure below shows the change in α when the relative steering entropy RHp changes, as shown in the figure above. The solid line in the figure below represents the change in α when the relative steering entropy RHp changes, as shown in the solid line in the figure above. The dashed line in the figure below represents the change in α when the relative steering entropy RHp changes, as shown in the dashed line in the figure above. In the figure below, α1 is the intervention level α determined by the intervention level determination unit 105 when the relative steering entropy RHp is RHp1, and α2 is the intervention level α determined by the intervention level determination unit 105 when the relative steering entropy RHp is RHp1.
[0036] The solid line in the figure below shows that the value increases without time lag in response to the change in relative steering entropy RHp. On the other hand, the dashed line in the figure below shows that α changes with a delay in response to the change in relative steering entropy RHp. The control steering angle determination unit 106 substitutes the α determined in this way into equation 9 and outputs the control steering angle Umix obtained sequentially to the steering angle control unit 20.
[0037] In the embodiment described above, the steering support system 10 determines a higher intervention level α in steering control as the relative steering entropy RHp indicates a higher driver load. In this way, the steering support system 10 does not intervene excessively when the driver is performing smooth steering, while increasing the intervention level when the driver is performing irregular and unstable steering. In other words, the steering support system 10 can perform appropriate steering intervention according to the driver's driving load.
[0038] 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 according to the driver's driving load state.
[0039] The control rudder angle determination unit 106 changes the intervention degree α used to determine the control rudder angle U mix faster to a value determined by the relative steering entropy RH p as the change speed of the relative steering entropy RH p increases. By doing so, it is possible to perform more appropriate steering intervention according to the state of the driver's driving load.
[0040] For example, when there is a pedestrian jumping out in an urban area and the driver performs a sudden steering operation, the relative steering entropy RH p rises rapidly. Therefore, the intervention degree α instantaneously increases, and the vehicle behavior can be controlled to be stable. If the pedestrian can be avoided and the relative steering entropy RH p decreases, the intervention degree α decreases and returns to the driver-centered steering.
[0041] On the other hand, when the relative steering entropy RH p increases due to slight fluctuations, the intervention degree α gradually increases, so that the steering assist is strengthened, lane departure can be suppressed, and the stability of the driving trajectory is improved. Examples of cases where slight fluctuations occur include when an elderly driver is driving on a highway or during a long-time driving.
[0042] The intervention degree α determined by the intervention degree determination unit 105 is set to 0.4, which is a value smaller than 0.5 as the upper limit value. Therefore, no matter how high the relative steering entropy RH p becomes, the intervention degree α does not exceed 0.4. When the intervention degree is smaller than 0.5, it is a driver-led steering operation. Therefore, according to the present embodiment, appropriate steering intervention can be performed according to the state of the driver's driving load within the range where the driver-led steering operation can be maintained.
[0043] The intervention degree α determined by the intervention degree determination unit 105 is set to 0.1 as the lower limit value. Since the lower limit value is set to 0.1, the intervention degree α does not become lower than 0.1 even when the relative steering entropy RH p is low. As a result, even when the driver's driving load is low, a little steering assistance by the steering support system 10 is performed, so that the driver's driving load for lane keeping is reduced.
[0044] Although the embodiments have been described above, the disclosed technology is not limited to the above-described embodiments. The following modification examples are also included in the disclosed scope, and various modifications can be made and implemented without departing from the gist thereof. In the following description, elements having the same reference numerals as those used so far are the same as the elements having the same reference numerals in the previous embodiments, unless otherwise specified. Also, when only a part of the configuration is described, the previously described embodiments can be applied to other parts of the configuration.
[0045] <Modification Example 1> In the embodiment, the intervention degree α determined by the intervention degree determination unit 105 was set with a lower limit value of 0.1 and an upper limit value of 0.4. However, the intervention degree α may be determined within the range from 0 to 1.
[0046] <Modification Example 2> In determining the intervention degree α, in addition to the relative steering entropy RHp, the driving environment may be considered. For example, the intervention degree α determined from the relative steering entropy RHp is corrected in consideration of the driving environment. The driving environment may include one or both of road surface conditions such as rainy days, snow accumulation, and freezing, and traffic density. These road surface conditions and traffic density can be determined using vehicle external environment sensors such as cameras, radars, LiDARs, and road surface friction estimation sensors. When considering the driving environment, in a driving environment where the driving load is high, such as in bad weather or congestion, the intervention degree α is increased even with the same relative steering entropy RHp compared to a driving environment where the driving load is relatively low.
[0047] <Modification Example 3> The steering assist ECU 100 only needs to include at least one of a processor and a circuit as a hardware configuration. Therefore, the steering assist ECU 100 is not limited to a configuration including a processor, and may be a configuration including no processor but including a hardware circuit other than the processor, or a configuration including a processor and a hardware circuit other than the processor.
[0048] (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.
[0049] (Technical Concept 1) A steering assist device comprising: an entropy determination unit (104) that sequentially acquires the steering angle and, based on the steering angle, sequentially determines a relative steering entropy (RHp) which is a value that expresses the smoothness of the driver's steering control in entropy and indicates the driver's most recent steering characteristics relative to the driver's normal steering characteristics; and an intervention degree determination unit (105) that determines a higher value for the degree to which the steering assist system (10) installed in the vehicle driven by the driver intervenes in the steering control as the relative steering entropy indicates a high load on the driver.
[0050] (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.
[0051] (Technical Concept 3) The steering assist device according to Technical Concept 2, wherein the control steering angle determination unit changes the degree of intervention used to determine the control steering angle to a value determined by the relative steering entropy as quickly as possible, the faster the rate of change of the relative steering entropy.
[0052] (Technical Concept 4) The steering assistance device according to any one of Technical Concepts 1 to 3, wherein the intervention degree determination unit determines the intervention degree to a progressively higher value as the relative steering entropy indicates a higher load on the driver.
[0053] (Technical Concept 5) The steering support device according to any one of Technical Concepts 1 to 3, wherein the intervention degree determination unit determines the intervention degree to a continuously higher value from a lower limit to an upper limit as the driver's load increases from the intervention change start value to the intervention change end value of the relative steering entropy.
[0054] (Technical Concept 6) A steering assistance device according to any one of Technical Concepts 1 to 5, wherein the intervention level is set to an upper limit less than 0.5.
[0055] (Technical Concept 7) A steering assistance device according to any one of Technical Concepts 1 to 6, wherein the degree of intervention is set to a lower limit greater than 0.
[0056] (Technical Concept 8) A substantial computer-readable recording medium that non-transitionally records a steering support program, which includes at least one processor, which sequentially acquires a steering angle, sequentially determines a relative steering entropy (RHp) based on the steering angle, which is a value that represents the smoothness of the driver's steering control in entropy and indicates the driver's most recent steering characteristics relative to the driver's normal steering characteristics, and determines a steering support program that determines a higher level of intervention by the steering support system (10) installed in the vehicle driven by the driver in steering control as the relative steering entropy indicates a higher load on the driver.
[0057] In the scope of this disclosure or claims, the term “processor” means one or more hardware processors configured to execute the processing defined by computer program code (i.e., one or more instructions of a computer program) contained in a computer program, by reading the computer program code each time. In other words, a “processor” is a hardware device that executes one or more programmed processes. Therefore, computer program code can also be said to be software that can define the processing of the processor according to its content. A “processor” can be a general-purpose or specific-purpose processor, and may be, but is not limited to, a CPU, microprocessor, GPU, and DFP (Data Flow Processor).
[0058] 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.
[0059] 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.
[0060] 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 support device comprising: an entropy determination unit (104) that sequentially acquires the steering angle and, based on the steering angle, sequentially determines a relative steering entropy (RHp), which is a value that expresses the smoothness of the driver's steering control in entropy and indicates the driver's most recent steering characteristics relative to the driver's normal steering characteristics; and an intervention degree determination unit (105) that determines a higher value for the degree to which the steering support system (10) installed in the vehicle driven by the driver intervenes in the steering control as the relative steering entropy indicates a high load on the driver.
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 assist device according to claim 2, wherein the control steering angle determination unit changes the degree of intervention used to determine the control steering angle to a value determined by the relative steering entropy as quickly as possible, the faster the rate of change of the relative steering entropy.
4. The steering assistance device according to any one of claims 1 to 3, wherein the intervention degree determination unit determines the intervention degree to a progressively higher value as the relative steering entropy indicates a higher load on the driver.
5. The steering assistance device according to any one of claims 1 to 3, wherein the intervention degree determination unit determines the intervention degree to a continuously higher value from a lower limit to an upper limit as the driver's load increases from the intervention change start value to the intervention change end value of the relative steering entropy.
6. The steering assistance device according to any one of claims 1 to 3, wherein the intervention level is set to an upper limit less than 0.
5.
7. The steering assistance device according to any one of claims 1 to 3, wherein a lower limit value greater than 0 is set for the degree of intervention.
8. A steering assistance program to cause at least one processor to function as: an entropy determination unit (104) that sequentially acquires the steering angle and, based on the steering angle, sequentially determines a relative steering entropy (RHp), which is a value that expresses the smoothness of the driver's steering control in entropy and indicates the driver's most recent steering characteristics relative to the driver's normal steering characteristics; and an intervention degree determination unit (105) that determines a higher intervention degree for the steering assistance system (10) installed in the vehicle being driven by the driver to intervene in the steering control as the relative steering entropy indicates a higher load on the driver.
9. A steering assistance method performed by at least one of a processor and a circuit, comprising: sequentially acquiring a steering angle; sequentially determining a relative steering entropy (RHp) based on the steering angle, which is a value that expresses the smoothness of the driver's steering control in entropy and indicates the driver's most recent steering characteristics relative to the driver's normal steering characteristics; and determining a higher intervention level for the steering assistance system (10) installed in the vehicle driven by the driver to intervene in the steering control as the relative steering entropy indicates a higher load on the driver.