A steering gain adaptive adjustment method considering driver muscle fatigue

Abstract

The present application is suitable for the field of vehicle engineering and human-computer interaction technology, and provides a steering gain adaptive adjustment method considering driver muscle fatigue, which comprises the following steps: step 1: by collecting vehicle data in real time, the characteristic quantity for judging whether the driver is driving while fatigued is obtained; step 2: based on the driver muscle fatigue level signal and the current vehicle speed, the target steering gain coefficient is calculated; step 3: steering wheel closed-loop feedback control and power execution. The method can significantly reduce the muscle strength required by the driver to maintain steering operation in a fatigued state, compensate for the decline in muscle control ability, make the steering feel "lighter", thereby smoothing the steering operation, reducing excessive correction or operation lag caused by fatigue, improving the comfort of long-time driving of the driver, stabilizing the steering operation, effectively reducing the steering instability and potential risks caused by muscle fatigue, and realizing the coordinated optimization of safety and comfort.

Description

Technical Field

[0001] This invention belongs to the fields of vehicle engineering and human-computer interaction technology, and in particular relates to an adaptive steering gain adjustment method that takes into account driver muscle fatigue. Background Technology

[0002] Driver fatigue is a major cause of traffic accidents. Current technologies for fatigue detection primarily rely on driver facial features, physiological signals, or lateral vehicle displacement (such as lane departure). These methods have limitations: facial recognition is greatly affected by lighting and occlusion; physiological signal detection requires contact sensors, resulting in a poor user experience; and lane departure warnings are reactive interventions, often too late. Especially in scenarios with continuous curves, where drivers make frequent steering maneuvers, traditional lane-line-based warning systems are prone to false alarms and struggle to distinguish between normal cornering maneuvers and signs of impending loss of steering control due to fatigue.

[0003] Currently, there is a lack of technical solutions that can smoothly and proactively guide driver operation by altering human-machine interaction characteristics in the early stages of fatigue, thereby preventing dangerous situations from occurring. Summary of the Invention

[0004] The purpose of this invention is to provide a steering gain adaptive adjustment method that takes into account driver muscle fatigue, thereby addressing the problems mentioned in the background section.

[0005] The present invention is implemented as follows: an adaptive steering gain adjustment method considering driver muscle fatigue includes the following steps:

[0006] Step 1: Obtain characteristic quantities for judging whether the driver is driving while fatigued by collecting vehicle data in real time;

[0007] By collecting the steering wheel angle during vehicle movement and steering wheel torque Calculate characteristic quantities to characterize driver muscle fatigue; the first fatigue characteristic quantity is the number of steering operations over a period of time. The second fatigue characteristic is the driver's steering torque fluctuation index. ;

[0008] Based on the number of steering operations and steering torque fluctuation index This is converted into a signal indicating the driver's muscle fatigue level. :

[0009] ;

[0010] in, and These are the weighting coefficients of the first fatigue characteristic and the second fatigue characteristic, respectively.

[0011] Output driver muscle fatigue level signal The range is between [0,1]. This indicates that the driver is in a state of high energy. This indicates that the driver is in a state of severe muscle fatigue;

[0012] Step 2: Based on driver muscle fatigue level signals and current vehicle speed Calculate the target steering gain coefficient ;

[0013] Step 3: Steering wheel closed-loop feedback control and power assist execution;

[0014] Based on target steering gain coefficient Combined with real-time collected driver input torque and current vehicle speed Calculate the steering assist torque To achieve the desired steering assist torque This is converted into a motor control signal and transmitted to the power steering motor, thereby enabling the power steering motor to provide the ideal assist torque. .

[0015] A further technical solution involves, in step 1, the number of turning operations. Based on the collected steering wheel angle Data; when the steering wheel angle When the angle exceeds 20°, it is recorded as the start of a valid steering operation. After the steering operation lasts for more than 1 second, when the steering wheel angle returns to the center position, it marks the end of this steering operation and is recorded as one steering operation.

[0016] Count the number of steering operations detected over a period of time. It serves as the primary fatigue characteristic quantity.

[0017] A further technical solution, in step 1, is to determine the steering torque fluctuation index. Based on the collected steering wheel torque The calculation is as follows: First, the variance of the steering wheel torque over a certain period of time is calculated. :

[0018] ;

[0019] in, It is the number of samples taken over a period of time; It is the average value of the steering wheel torque over a period of time; It is the steering wheel torque for the i-th steering operation;

[0020] Then calculate the driver's individual steering wheel torque baseline value. By continuously measuring the variance of steering wheel torque over multiple time windows Calculate their average value to obtain:

[0021] ;

[0022] in, It is the number of time windows;

[0023] By calculating the variance of steering torque over a period of time and comparing it with the driver's individual baseline value, the percentage of relative change is calculated as the second fatigue characteristic, namely the steering torque fluctuation index. :

[0024] .

[0025] In a further technical solution, step 2 includes the following specific steps:

[0026] Based on current vehicle speed Query the preset base assist gain mapping table of the vehicle's EPS system to obtain the base gain value. ;

[0027] Based on driver muscle fatigue level signals The fatigue adjustment coefficient was calculated. :

[0028] ;

[0029] in, This is the upper limit of the fatigue adjustment coefficient, taken as... K is the shape factor, used to adjust the growth rate of the function curve;

[0030] The function satisfies when hour, ;when As the value increases, the fatigue adjustment coefficient also increases.

[0031] Base gain value Multiply by the fatigue adjustment coefficient The target steering gain coefficient is obtained. :

[0032] .

[0033] A further technical solution is that, in step 3, the steering assist torque... The calculation formula is as follows:

[0034] ;

[0035] in, It is a traditional power assist mapping function based on vehicle speed, providing basic power assist; It is the damping coefficient, which is the coefficient of friction when the driver turns the steering wheel quickly and at a high frequency. This will increase, and this will generate a damping torque, thus increasing the steering feel.

[0036] This invention provides an adaptive steering gain adjustment method that considers driver muscle fatigue. This method determines driver fatigue by collecting fatigue characteristic quantities during continuous vehicle operation. Before the driver exhibits significant lane departure, it identifies muscle fatigue earlier by real-time monitoring of intrinsic behavioral characteristics such as steering operation frequency and torque fluctuation, before the driver makes significant operational errors (such as large-scale lane departure). This is achieved by using fatigue level signals... Mapped to the steering gain adjustment coefficient, it dynamically increases the effective assist gain of the electric power steering system, significantly reducing the muscle strength required for the driver to maintain steering operation (especially in continuous curves) under fatigue, compensating for the decline in muscle control ability, making the steering feel "lighter", thus smoothing the steering operation, reducing overcorrection or operation lag caused by fatigue, improving the driver's comfort during long-term driving, and effectively reducing steering instability and potential accident risks caused by muscle fatigue by stabilizing steering operation, achieving synergistic optimization of safety and comfort. Attached Figure Description

[0037] Figure 1 A flowchart of a steering gain adaptive adjustment method considering driver muscle fatigue provided in an embodiment of the present invention;

[0038] Figure 2 A schematic diagram illustrating the adjustment effect under different fatigue level signals;

[0039] Figure 3 This is a diagram illustrating the comparison of adjustment effects. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0041] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0042] like Figure 1 As shown, an embodiment of the present invention provides a method for adaptive adjustment of steering gain considering driver muscle fatigue, comprising the following steps:

[0043] Step 1: Obtain characteristic quantities for judging whether the driver is driving while fatigued by collecting vehicle data in real time;

[0044] By collecting the steering wheel angle during vehicle movement and steering wheel torque The characteristic quantities used to characterize driver muscle fatigue were calculated. The first fatigue characteristic quantity was the number of steering operations over a period of time. The second fatigue characteristic is the driver's steering torque fluctuation index. .

[0045] Number of steering operations Based on the collected steering wheel angle Data. When the steering wheel angle is turned... A steering operation is considered valid when the angle exceeds 20°. The operation lasts for more than 1 second, and ends when the steering wheel angle returns to approximately the center position. This is recorded as one steering operation. The number of steering operations detected over a period of time is counted. It serves as the primary fatigue characteristic quantity.

[0046] Steering torque fluctuation index Based on the collected steering wheel torque Calculations show that when fatigued, a driver's muscle control decreases, leading to more frequent and abrupt minor steering corrections. This results in unstable steering wheel torque output and increased variance.

[0047] ;

[0048] in, It is the variance of steering wheel torque over a period of time; It is the number of samples taken over a period of time; It is the average value of the steering wheel torque over a period of time; It is the steering wheel torque for the i-th steering operation.

[0049] Driver's personal steering wheel torque baseline This involves measuring the variance of steering wheel torque across multiple time windows during the initial driving period after vehicle ignition, when the driver is most alert. Calculate their average value to obtain:

[0050] ;

[0051] in, It is the number of time windows.

[0052] The relative percentage change in steering torque over a period of time is calculated and compared with the driver's individual baseline value, serving as the second fatigue characteristic.

[0053] ;

[0054] Based on the number of steering operations and steering torque fluctuation index This is converted into a signal indicating the driver's muscle fatigue level. :

[0055] ;

[0056] in, and These are the weighting coefficients of the first fatigue characteristic and the second fatigue characteristic, respectively.

[0057] Output driver muscle fatigue level signal The range is between [0,1]. This indicates that the driver is in a state of high energy. This indicates that the driver is in a state of severe muscle fatigue.

[0058] Step 2: Based on driver muscle fatigue level signals and current vehicle speed Calculate the target steering gain coefficient;

[0059] Based on current vehicle speed Query the preset base assist gain mapping table of the vehicle's EPS system to obtain the base gain value. .

[0060] Based on driver muscle fatigue level signals The fatigue adjustment coefficient was calculated. :

[0061] ;

[0062] in, This is the upper limit of the fatigue adjustment coefficient, to prevent excessive power assistance from causing a complete loss of road feel. K is the shape factor, used to adjust the growth rate of the function curve.

[0063] The function satisfies when hour, ;when As the value increases, the fatigue adjustment coefficient also increases.

[0064] Base gain value Multiply by the fatigue adjustment coefficient The target steering gain coefficient is obtained. :

[0065] ;

[0066] Step 3: Steering wheel closed-loop feedback control and power assist execution;

[0067] Based on target steering gain coefficient Combined with real-time collected driver input torque With current vehicle speed Calculate the steering assist torque :

[0068] ;

[0069] in, It is a traditional power assist mapping function based on vehicle speed, providing basic power assist; It is the damping coefficient, which is the coefficient of friction when the driver turns the steering wheel quickly and at a high frequency. This will increase, and this will generate a strong damping torque, which will improve the steering feel.

[0070] To achieve the desired steering assist torque This is converted into a motor control signal and transmitted to the power steering motor, thereby enabling the power steering motor to provide the ideal assist torque. This changes the steering force felt by the driver, allowing for adjustments to the electric power steering system that take into account driver muscle fatigue.

[0071] Figure 2 These are the different fatigue level signals of this invention. The diagram below illustrates the adjustment effect. Figure 2 This demonstrates the steering feel curve (the relationship between driver input torque and steering wheel angle) as fatigue level increases. A dynamic and changing relationship. Fatigue level signal. At this time, the driver is in a state of high alertness. As the fatigue level signal increases, the driver's muscle fatigue gradually increases. Under the effect of this method, the steering wheel torque required for the driver to complete the steering operation decreases accordingly. The muscle strength required for the driver to maintain steering operation (especially in continuous curves) in a fatigued state is reduced, making the steering feel "lighter" and thus smoothing the steering operation.

[0072] Figure 3 This is a diagram illustrating the adjustment effect of this method when the driver performs steering operations. Figure 3The steering feel curves without and with this adjustment method were compared when the driver performed the same steering operation (the driver performs a turn at a speed of 20 km / h after a period of continuous turning). Under this adjustment method, the steering torque required for the driver to complete the same steering operation is reduced. This method effectively compensates for the decline in the driver's muscle control ability, smooths the steering operation, and thus improves the safety and comfort of continuous driving.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for adaptive adjustment of steering gain considering driver muscle fatigue, characterized in that, Includes the following steps: Step 1: Obtain characteristic quantities for judging whether the driver is driving while fatigued by collecting vehicle data in real time; By collecting the steering wheel angle during vehicle movement and steering wheel torque Calculate the characteristic quantities used to characterize driver muscle fatigue; The primary fatigue characteristic is the number of steering operations within a certain period of time. The second fatigue characteristic is the driver's steering torque fluctuation index. ; Based on the number of steering operations and steering torque fluctuation index This is converted into a signal indicating the driver's muscle fatigue level. : ； in, and These are the weighting coefficients of the first fatigue characteristic and the second fatigue characteristic, respectively. Output driver muscle fatigue level signal The range is between [0,1]. This indicates that the driver is in a state of high energy. This indicates that the driver is in a state of severe muscle fatigue; Step 2: Based on driver muscle fatigue level signals and current vehicle speed Calculate the target steering gain coefficient ; Step 3: Steering wheel closed-loop feedback control and power assist execution; Based on target steering gain coefficient Combined with real-time collected driver input torque and current vehicle speed Calculate the steering assist torque To achieve the desired steering assist torque This is converted into a motor control signal and transmitted to the power steering motor, thereby enabling the power steering motor to provide the ideal assist torque. ; In step 1, the steering torque fluctuation index Based on the collected steering wheel torque The calculation is as follows: First, the variance of the steering wheel torque over a certain period of time is calculated. : ； in, It is the number of samples taken over a period of time; It is the average value of the steering wheel torque over a period of time; It is the steering wheel torque for the i-th steering operation; Then calculate the driver's individual steering wheel torque baseline value. By continuously measuring the variance of steering wheel torque over multiple time windows Calculate their average value to obtain: ； in, It is the number of time windows; By calculating the variance of steering torque over a period of time and comparing it with the driver's individual baseline value, the percentage of relative change is calculated as the second fatigue characteristic, namely the steering torque fluctuation index. : 。 2. The adaptive steering gain adjustment method considering driver muscle fatigue according to claim 1, characterized in that, In step 1, the number of turning operations Based on the collected steering wheel angle Data; when the steering wheel angle When the angle exceeds 20°, it is recorded as the start of a valid steering operation. After the steering operation lasts for more than 1 second, when the steering wheel angle returns to the center position, it marks the end of this steering operation and is recorded as one steering operation. Count the number of steering operations detected over a period of time. It serves as the primary fatigue characteristic quantity.

3. The adaptive steering gain adjustment method considering driver muscle fatigue according to claim 1, characterized in that, Step 2 includes the following specific steps: Based on current vehicle speed Query the preset base assist gain mapping table of the vehicle's EPS system to obtain the base gain value. ; Based on driver muscle fatigue level signals The fatigue adjustment coefficient was calculated. : ； in, This is the upper limit of the fatigue adjustment coefficient, taken as... K is the shape factor, used to adjust the growth rate of the function curve; The function satisfies when hour, ;when As the value increases, the fatigue adjustment coefficient also increases. Base gain value Multiply by the fatigue adjustment coefficient The target steering gain coefficient is obtained. : 。 4. The adaptive steering gain adjustment method considering driver muscle fatigue according to claim 3, characterized in that, In step 3, the steering assist torque The calculation formula is as follows: ； in, It is a traditional power assist mapping function based on vehicle speed, providing basic power assist; It is the damping coefficient, which is the coefficient of friction when the driver turns the steering wheel quickly and at a high frequency. This will increase, and this will generate a damping torque, thus increasing the steering feel.

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