JP7207136B2 - Steering state detection device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering state detection device for detecting a steering state of a driver's steering wheel.

2. Description of the Related Art As one of vehicle driving assistance, there is a demand for a technique for detecting whether or not a driver is properly gripping a steering wheel while the vehicle is running. For example, it has been proposed to warn the driver if he loses consciousness and lets go of the steering wheel.
In Japanese Unexamined Patent Application Publication No. 2002-100000, it is determined whether or not the steering wheel is in the hands-free state by filtering the obtained time-series data of the steering torque to remove the data in the high frequency range.

JP 2017-124648 A

However, the filter processing described in Patent Document 1 tends to take a long processing time. Therefore, there is a demand for a technique capable of quickly and accurately detecting a hands-free state without filtering.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to detect the hand-off state of the steering wheel quickly and accurately.

In one aspect of the present invention, a torque acquisition unit that sequentially acquires a steering torque applied to a steering wheel of a vehicle; a calculation unit that calculates an average value of the sequentially acquired steering torque and a standard deviation of the steering torque; a state determination unit that determines whether or not the steering wheel is in a hands-free state indicating a state in which the steering wheel is not held while the vehicle is running, based on the average value and the standard deviation of the steering torque. A rudder state detection device is provided.

The state determination unit performs a first determination as to whether or not a first condition in which the average value is smaller than a first threshold value and the standard deviation is smaller than a second threshold value is satisfied. When the first condition is satisfied, a second determination as to whether or not the hands are in the hands-free state may be performed based on the number of times the first condition is satisfied.

Further, the state determination unit may determine that the hands are in the hands-free state when the ratio of the number of times the first condition is satisfied is greater than a third threshold value in the second determination.

Further, the state determination unit determines that the state is in the hands-free state in the previous determination even if the ratio is equal to or less than the third threshold value in the repeatedly performed second determination, and the ratio is the third threshold value. If it is greater than a fourth threshold that is smaller than , it may be determined that the hand is in the hands-free state.

Further, the state determination unit may change the fourth threshold according to the speed of the vehicle, and determine that the vehicle is in the hands-free state when the ratio is greater than the changed fourth threshold. good.

ADVANTAGE OF THE INVENTION According to this invention, it is effective in being able to detect the hands-off state of a steering wheel rapidly and with high precision.

1 is a schematic diagram showing part of the configuration of a vehicle 1; FIG. 1 is a block diagram for explaining an example of a configuration of a steering-held state detection device 100; FIG. 5 is a flow chart showing an example of a steering holding state detection process;

<Overview of vehicle>
An overview of a vehicle equipped with a steering state detection device according to one embodiment of the present invention will be described with reference to FIG.

FIG. 1 is a schematic diagram showing a part of the configuration of the vehicle 1. As shown in FIG. Vehicle 1 is a truck as an example here. As shown in FIG. 1 , the vehicle 1 has a steering wheel 10 , a steering shaft 20 , a steering mechanism section 30 , wheels 40 , an alarm device 50 and a steering holding state detection device 100 .

The steering wheel 10 is provided so as to be rotatable about an axis, and is a member for the driver to steer the vehicle 1 in the traveling direction. The driver changes the traveling direction of the wheels 40 by rotating the steering wheel 10 forward or backward while gripping it. When the driver rotates the steering wheel 10 while gripping it, steering torque is applied to the steering wheel 10 .

The steering shaft 20 is a rotating shaft that rotates together with the steering wheel 10 . A steering torque applied to the steering wheel 10 is transmitted to the steering shaft 20 . The steering shaft 20 is provided with a detection sensor 22 for detecting a torque value of steering torque. The detection sensor 22 may detect the steering angle of the steering shaft 20 .

The steering mechanism section 30 is a mechanism section for changing the traveling direction of the vehicle 1 according to the rotation of the steering wheel 10 . The steering mechanism portion 30 has a pinion shaft 31, a rack shaft 32, and a tie rod 35 here. A pinion gear 31 a is provided at the lower end of the pinion shaft 31 . A rack gear 32a that meshes with the pinion gear 31a is provided in the center of the rack shaft 32. As shown in FIG. The tie rods 35 are provided at both ends of the rack shaft 32 .

The wheels 40 are the front wheels of the vehicle 1 here. Wheels 40 are connected to tie rods 35 . The steering direction of the wheels 40 changes according to the rotation of the steering wheel 10 .

The alarm device 50 is a device that issues an alarm. The alarm device 50 alerts the driver by, for example, sounding a sound. The alarm device 50 issues an alarm when the driver has let go of the steering wheel 10 .

The steering holding state detection device 100 is a device for detecting whether the driver is gripping the steering wheel 10 or whether the driver is letting go of the steering wheel 10 . The steering-held state detection device 100, which will be described later in detail, quickly and highly accurately detects, for example, a state in which the driver loses consciousness and lets go of the steering wheel 10. FIG.

A detection result of the steering holding state detection device 100 is used for driving assistance of the vehicle 1 . For example, the steering-held state detection device 100 causes the warning device 50 to continue issuing a warning while it is determined that the driver has lost consciousness and has let go of the steering wheel 10 . If the driver does not respond appropriately to the warning, it is assumed that the driver is in an abnormal state, and the steering holding state detection device 100 takes measures such as stopping the vehicle 1, for example. As a result, safety while the vehicle 1 is traveling can be enhanced.

<Detailed configuration of steering holding state detection device>
A detailed configuration of the steering holding state detection device 100 will be described with reference to FIG. 2 .

FIG. 2 is a block diagram for explaining an example of the configuration of the steering holding state detection device 100. As shown in FIG. The steering-held state detection device 100 has a storage section 110 and a control section 120, as shown in FIG.

The storage unit 110 includes, for example, ROM (Read Only Memory) and RAM (Random Access Memory). The storage unit 110 stores programs and various data for the control unit 120 to execute. For example, the storage unit 110 stores information regarding steering torque detected by the detection sensor 22 .

The control unit 120 is, for example, a CPU (Central Processing Unit). Control unit 120 controls the operation of steering holding state detection device 100 by executing a program stored in storage unit 110 . Control unit 120 functions as torque acquisition unit 122 , calculation unit 124 , state determination unit 126 and alarm control unit 128 .

The torque acquisition unit 122 sequentially acquires steering torque applied to the steering wheel 10 of the vehicle 1 . The torque acquisition unit 122 acquires the steering torque detected by the detection sensor 22 from the detection sensor 22 . For example, the torque acquisition unit 122 acquires time-series data of steering torque continuously detected by the detection sensor 22 for a predetermined period of time while the vehicle is running. The torque acquisition unit 122 may cause the storage unit 110 to store the acquired time-series data of the steering torque.

Note that the steering torque when the driver is steering (holding) the steering wheel 10 is different from the steering torque when the driver is letting go of the steering wheel 10 . Specifically, the magnitude and degree of variation in the steering torque when the driver holds the steering wheel 10 are greater than when the driver releases the steering wheel 10 . When the driver releases the steering wheel 10, the steering torque hardly changes and the magnitude of the steering torque is small.

The calculation unit 124 obtains the average value of the steering torque sequentially obtained by the torque obtaining unit 122 and the standard deviation of the steering torque. For example, the calculation unit 124 obtains a moving average value A1 obtained by moving and averaging a predetermined number N1 of steering torques in the time-series data of the steering torque, and a standard deviation S1 of the predetermined number N1 of steering torques obtained by moving averaging. Calculation unit 124 outputs moving average value A<b>1 and standard deviation S<b>1 thus obtained to state determination unit 126 . Calculation unit 124 sequentially obtains moving average value A1 and standard deviation S1 while the vehicle is running, and continues to output them to state determination unit 126 . The predetermined number N1 is 30 as an example.

The state determination unit 126 determines whether the driver is holding the steering wheel 10 or letting go of the steering wheel 10 . In the present embodiment, the state determination unit 126 determines a state in which the steering wheel 10 is not held while the vehicle is running, based on the moving average value A1 and the standard deviation S1 of the steering torque obtained by the calculation unit 124. Determine whether or not there is

From the viewpoint of suppressing erroneous detection due to disturbance, the state determination unit 126 performs initial determination and final determination to determine whether or not the hand is in the hands-free state. In this embodiment, the initial determination corresponds to the first determination, and the final determination corresponds to the second determination.

As an initial determination, the state determination unit 126 determines whether or not a first condition in which the moving average value A1 is smaller than the threshold K1 (first threshold) and the standard deviation S1 is smaller than the threshold K2 (second threshold) is satisfied. make a judgment. The state determination unit 126 estimates that the driver may be in a state of letting go of the steering wheel 10 when the first condition is satisfied. On the other hand, the state determination unit 126 determines that the driver is gripping the steering wheel 10 when the first condition is not satisfied. State determination unit 126 outputs 1 as a determination value when the first condition is satisfied, and outputs 0 as a determination value when the first condition is not satisfied. Note that the threshold K1 and the threshold K2 are values set by experiments or the like.

When the first condition is satisfied in the initial determination, the state determination unit 126 performs the following final determination. When the first condition is satisfied in the initial determination, the state determination unit 126 determines whether or not the hand is in the hands-free state based on the number of times the first condition is satisfied. Specifically, in this determination, the state determination unit 126 determines that the hands are in the hands-free state when the ratio of the number of times that the first condition is satisfied in the predetermined number of times N2 is greater than the threshold K3 (third threshold). The ratio of the number of times that the first condition is satisfied is the determination average value A2 obtained by averaging the determination values (1 or 0) of the predetermined number of times N2. The determination average value A2 is a value between 0 and 1. As an example, the threshold K3 is 0.95 and the predetermined number of times N2 is 30 times.

In the second determination, which is repeatedly performed, even if the determination average value A2 is equal to or less than the threshold value K3, the state determination unit 126 determines that the immediately preceding determination value is 1 and the determination average value A2 is smaller than the threshold value K3. threshold), it is determined to be in the hands-free state. The threshold K4 is 0.60 as an example. By setting the above-described threshold value K4, even if the determination average value A2 fluctuates due to disturbance or the like, it is possible to suppress a state (unstable state) in which an alarm may or may not sound.

In the above description, the threshold value K4 is assumed to be a fixed value, but it is not limited to this. Threshold K4 may be a variable value. For example, the state determination unit 126 may change the threshold K4 according to the speed of the vehicle 1. Specifically, the state determination unit 126 decreases the threshold K4 when the speed of the vehicle 1 is high, and increases the threshold K4 when the speed of the vehicle 1 is low (specifically, the threshold K4 is set to be smaller than the threshold K3. increase K4). Then, in this determination, if the determination average value A2 is greater than the changed threshold value K4, the state determination unit 126 determines that the hands are in the hands-free state. As a result, when the speed of the vehicle 1 is high, the alarm is likely to sound, making it easier to avoid danger.

The alarm control section 128 controls the operation of the alarm device 50 of the vehicle 1 . When the state determination unit 126 determines that the driver is in the hands-free state, the alarm control unit 128 causes the alarm device 50 to issue an alarm to alert the driver.

<Held steering state detection process>
The flow of the steering state detection process performed by the steering state detection device 100 will be described with reference to FIG.

FIG. 3 is a flow chart showing an example of a steering holding state detection process. The steering holding state detection process is implemented by control unit 120 executing a program stored in storage unit 110 . The processing shown in FIG. 3 is performed while the vehicle 1 is running. For example, this process is executed when the vehicle 1 is traveling at a speed of 5 (km/h) or more per hour.

First, the torque acquisition unit 122 sequentially acquires the steering torque (step S102). The torque acquisition unit 122 acquires time-series data of the steering torque detected by the detection sensor 22 .

Next, the calculation unit 124 obtains the average value (moving average value A1) of the predetermined number N1 of the steering torques and the standard deviation S1 of the predetermined number N1 of the steering torques in the time-series data of the steering torque (step S104). ). The calculation unit 124 continues to obtain the moving average value A1 and the standard deviation S1 while the torque acquisition unit 122 acquires the steering torque.

Next, as an initial determination, the state determination unit 126 determines whether or not a first condition is satisfied in which the moving average value A1 is smaller than the first threshold value K1 and the standard deviation S1 is smaller than the second threshold value K2 (step S106). ). State determination unit 126 outputs 1 as the determination value when the first condition is satisfied, and outputs 0 as the determination value when the first condition is not satisfied.

If the first condition is satisfied in step S106 (Yes), the state determination unit 126 makes this determination (steps S108 to S116). At this time, the state determination unit 126 determines whether or not the first condition is satisfied a plurality of times, and obtains a determination average value A2 by moving and averaging a predetermined number N2 of determination values.

Next, state determination unit 126 determines whether determination average value A2 is greater than threshold value K3 (0.95) (step S110). If the determination average value A2 is greater than the threshold value K3 in step S110 (Yes), the state determination unit 126 determines that the hands are in the hands-free state (step S112). When it is determined that the hand is released, the alarm control unit 128 causes the alarm device 50 to sound an alarm. When the driver notices the warning and grips the steering wheel 10, the subsequent steering torque increases. On the other hand, for example, a driver who has lost consciousness does not grip the steering wheel 10 even if the alarm sounds, so the steering torque hardly fluctuates.

After that, the state determination unit 126 continues to determine whether or not the hand is in the hands-free state. Specifically, the state determination unit 126 determines whether or not a second condition is satisfied in which the immediately preceding determination value is 1 and the determination average value A2 is greater than the threshold value K4 (0.60) (step S114). . For example, when the driver holds the steering wheel 10, the second condition is not satisfied, and when the driver continues to let go of the steering wheel 10, the second condition is satisfied.

If the second condition is not satisfied in step S114 (No), the state determination unit 126 determines that the gripping state is established (step S116). On the other hand, if the second condition is satisfied in step S114 (Yes), the state determination unit 126 continues to determine that the hand is in the hands-free state (step S112). Then, the alarm control unit 128 causes the alarm device 50 to continue sounding the alarm.

<Effects of this embodiment>
The steering-held state detection device 100 described above obtains the moving average value A1 and the standard deviation S1 of the steering torque from the time-series data of the steering torque that are sequentially acquired. Based on the moving average value A1 and the standard deviation S1 thus obtained, the steering-held state detection device 100 determines whether or not the steering wheel 10 is not held while the vehicle is running.
As a result, it is possible to determine whether or not the hands are in the hands-free state without performing filter processing on the time series data of the steering torque. Further, by making a determination using the moving average value A1 and the standard deviation S1, it is possible to detect the hands-free state with high accuracy.

Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist thereof. be. For example, all or part of the device can be functionally or physically distributed and integrated in arbitrary units. In addition, new embodiments resulting from arbitrary combinations of multiple embodiments are also included in the embodiments of the present invention. The effect of the new embodiment caused by the combination has the effect of the original embodiment.

Reference Signs List 1 vehicle 10 steering wheel 100 steering holding state detection device 122 torque acquisition unit 124 calculation unit 126 state determination unit

Claims (4)

a torque acquisition unit that sequentially acquires steering torque applied to the steering wheel of the vehicle;
a calculating unit for obtaining a moving average of the sequentially acquired absolute values of the steering torque and a standard deviation of the absolute values of the steering torque;
a state determination unit that determines whether or not the steering wheel is in a hands-free state indicating that the steering wheel is not held while the vehicle is running, based on the obtained moving average value and the standard deviation of the steering torque;
with
The state determination unit
making a first determination as to whether the moving average value is smaller than the first threshold and the standard deviation is smaller than the second threshold and a first condition is satisfied;
A device for detecting a holding state of steering , which performs a second determination as to whether or not the hand is released based on the number of times the first condition is satisfied when the first condition is satisfied in the first determination . The state determination unit
In the second determination, if the ratio of the number of times that the first condition is satisfied is greater than a third threshold, it is determined that the hand is released.
The steering holding state detection device according to claim 1 . The state determination unit
In the repeatedly performed second determination, even if the ratio is equal to or less than the third threshold, the immediately preceding determination determines that the hands are in the hands-free state, and the ratio is lower than the fourth threshold, which is smaller than the third threshold. If it is larger, determine that it is in the hands-free state;
The steering holding state detection device according to claim 2 . The state determination unit
changing the fourth threshold according to the speed of the vehicle;
If the ratio is greater than the fourth threshold after the change, it is determined that the hand is released.
The steering holding state detection device according to claim 3 .

Images