CN114624780A - Steering wheel hands-off detection method, device and medium - Google Patents
Steering wheel hands-off detection method, device and medium Download PDFInfo
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Abstract
The application discloses a method, a device and a medium for detecting steering wheel hands off, comprising the following steps: the method comprises the steps of obtaining first reference variable quantity of a capacitance detection value of a steering wheel in each detection period, and calculating second reference variable quantity and first operation variable quantity in a preset period so as to determine whether the steering wheel is out of hand according to the change situation of the capacitance detection value at the steering wheel, wherein the second reference variable quantity is the sum of the first reference variable quantities in the preset period, and the first operation variable quantity is the sum of the first reference variable quantities with absolute values larger than a first operation threshold value. Correcting the first operation variable quantity by using the second reference variable quantity to obtain a second operation variable quantity; so as to prevent the detected capacitance value change caused by the temperature change from interfering with the hands-off detection result, and determine whether the steering wheel is hands-off according to the second operation change amount. This application is through revising first operation variable quantity to prevent the temperature and detect the interference that causes, improve the rate of accuracy that the steering wheel breaks away from the hand.
Description
Technical Field
The application relates to the field of automobile control, in particular to a method, a device and a medium for detecting the hands-off of an automobile steering wheel.
Background
When an emergency situation occurs or the attention of a driver is affected during driving of an automobile, the hands of the driver may be separated from the steering wheel, which may cause a traffic accident. Therefore, whether the steering wheel is out of hand needs to be detected so as to take measures in time after the steering wheel is out of hand, and the method and the device have important significance for safe driving.
The operation of the steering wheel by the driver and whether the two hands of the driver are in contact with the steering wheel are detected by a capacitance type detection film wrapped on the surface of the steering wheel, so that whether the steering wheel is out of hand is determined. However, since the surface of the steering wheel has a heating film, the temperature change of the heating film affects the detection result of the capacitive detection film, thereby causing erroneous judgment.
Therefore, the problem to be solved by the technical personnel in the field is how to provide a new system for detecting the steering wheel out-of-hand to achieve the purpose of suppressing the interference of the temperature change on the detection result and improving the accuracy of the steering wheel out-of-hand detection.
Disclosure of Invention
The application aims to provide a method, a device and a medium for detecting the steering wheel hands-off, so as to achieve the purposes of inhibiting the interference of temperature change on a detection result and improving the accuracy of the steering wheel hands-off detection.
In order to solve the above technical problem, the present application provides a method for detecting a steering wheel out of hand, including:
acquiring a first reference variable quantity of a capacitance detection value of a steering wheel in each detection period;
calculating a second reference variation in a preset period, wherein the second reference variation is the sum of all the first reference variations in the preset period;
calculating a first operation variation in a preset period, wherein the first operation variation is the sum of each first reference variation with an absolute value larger than a first operation threshold;
correcting the first operation variable quantity by using the second reference variable quantity to obtain a second operation variable quantity;
and judging the working state of the steering wheel according to the second operation variable quantity.
Preferably, the acquiring a first reference variation of the capacitance detection value of the steering wheel in each detection cycle includes:
acquiring a steering wheel capacitance measurement value and an environment capacitance measurement value;
calculating the first baseline variation from the steering wheel capacitance measurement and the ambient capacitance measurement.
Preferably, after the step of obtaining the steering wheel capacitance measurement value and the environmental capacitance measurement value, the method further includes:
performing a filtering operation on the steering wheel capacitance measurement and the ambient capacitance measurement.
Preferably, after the step of calculating the first reference variation amount according to the steering wheel capacitance measurement value and the environment capacitance measurement value, the method further includes:
acquiring a current heating unit temperature value;
and performing temperature compensation operation on the first reference variable quantity according to the current heating unit temperature value.
Preferably, the correcting the first operation variation by using the second reference variation to obtain a second operation variation includes:
setting the second operation variation as a difference between the second reference variation and the second operation threshold if the first operation variation is larger than the difference between the second reference variation and the second operation threshold;
when the second reference variation is larger than the third operation threshold, if the first operation variation is smaller than the difference between the second reference variation and the third operation threshold, setting the second operation variation as the difference between the second reference variation and the third operation threshold;
setting the second operation variation as a difference between the second reference variation and the second operation threshold if the first operation variation is larger than the difference between the second reference variation and the second operation threshold;
wherein the second operational threshold is less than the third operational threshold.
Preferably, the judging the operating state of the steering wheel according to the second operation variation includes:
the working state comprises: a strong touch state, a weak touch state and a hands-off state;
if the second operation variable quantity is larger than a first touch threshold value, determining that the steering wheel is in the strong touch state;
if the second operation variation is not larger than the first touch threshold and larger than a second touch threshold, determining that the steering wheel is in the weak touch state;
and if the second operation variation is not larger than the second touch threshold, determining that the steering wheel is in the hands-off state.
Preferably, after the step of determining the operating state of the steering wheel according to the second operation variation, the method further includes:
setting a first hysteresis parameter and a second hysteresis parameter;
when the steering wheel is in the strong collision state or the weak collision state, judging whether the second operation variation is smaller than the difference between the second touch threshold and the first hysteresis parameter;
if the working state is smaller than the preset working state, setting the working state as a hands-off state;
when the working state is in the strong touch state, judging whether the second operation variation is smaller than the difference between the first touch threshold and the second hysteresis parameter or not, and the second operation variation is not smaller than the difference between the second touch threshold and the first hysteresis parameter;
and if so, setting the working state as a weak collision state.
In order to solve the above technical problem, the present application further provides a steering wheel hands-off detection device, including:
the acquisition module is used for acquiring a first reference variable quantity of a capacitance detection value of the steering wheel in each detection period;
the first calculation module is used for calculating a second reference variation in a preset period, and the second reference variation is the sum of all the first reference variations in the preset period;
the second calculation module is used for calculating a first operation variation in a preset period, wherein the first operation variation is the sum of all first reference variations of which the absolute values are larger than a first operation threshold;
the correction module is used for correcting the first operation variable quantity by using the second reference variable quantity so as to obtain a second operation variable quantity;
and the judging module is used for judging the working state of the steering wheel according to the second operation variable quantity.
In order to solve the above technical problem, the present application further provides a steering wheel hands-off detection device, including a memory for storing a computer program;
a processor for implementing the steps of the steering wheel hands-off detection method when executing the computer program.
In order to solve the above technical problem, the present application further provides a computer-readable storage medium, where a computer program is stored, and the computer program, when executed by a processor, implements the steps of the steering wheel hands-off detection method.
The steering wheel hands-off detection method provided by the application comprises the following steps: the method comprises the steps of obtaining first reference variable quantity of a capacitance detection value of a steering wheel in each detection period, and calculating second reference variable quantity in a preset period and first operation variable quantity in the preset period so as to determine whether the steering wheel is out of hand according to the change situation of the capacitance detection value at the steering wheel, wherein the second reference variable quantity is the sum of the first reference variable quantities in the preset period, and the first operation variable quantity is the sum of the first reference variable quantities with absolute values larger than a first operation threshold value. Correcting the first operation variable quantity by using the second reference variable quantity to obtain a second operation variable quantity; so as to prevent the capacitance detection value change caused by the temperature change from interfering the hand-off detection result. And judging the working state of the steering wheel according to the second operation variable quantity so as to determine whether the steering wheel is out of hand. Therefore, according to the scheme provided by the application, the first operation variable quantity is corrected, so that the interference of temperature on capacitance detection is prevented, and the accuracy of the steering wheel hands-off detection is improved.
In addition, the application also provides a steering wheel hands-off detection device and medium, which correspond to the method and have the same effects.
Drawings
In order to more clearly illustrate the embodiments of the present application, the drawings needed for the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings can be obtained by those skilled in the art without inventive effort.
Fig. 1 is a structural diagram of a steering wheel hands-off detection system according to an embodiment of the present disclosure;
fig. 2 is a flowchart of a method for detecting steering wheel hands-off according to an embodiment of the present disclosure;
fig. 3 is a structural diagram of a steering wheel hands-off detection device according to an embodiment of the present disclosure;
fig. 4 is a structural diagram of another steering wheel hands-off detection device provided in an embodiment of the present application;
the reference numbers are as follows: 1 is a control unit, 2 is a first one-way conduction device, 3 is a second one-way conduction device, and 4 is a detection/heating unit.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without any creative effort belong to the protection scope of the present application.
The core of the application is to provide a method, a device and a medium for detecting the hands-off of a steering wheel.
In order that those skilled in the art will better understand the disclosure, the following detailed description is given with reference to the accompanying drawings.
When a driver encounters an emergency or the attention of the driver is affected while driving a car, the hands of the driver may be separated from the steering wheel, causing a traffic accident. In order to improve the safety of automobile driving, the application provides a steering wheel hands-off detection method, which includes the steps of obtaining first reference variable quantities of capacitance detection values of a steering wheel in each detection period, and calculating second reference variable quantities in a preset period and first operation variable quantities in the preset period so as to determine whether the steering wheel is hands-off or not according to the change situation of the capacitance detection values at the steering wheel, wherein the second reference variable quantities are the sum of the first reference variable quantities in the preset period, and the first operation variable quantities are the sum of the first reference variable quantities of which the absolute values are larger than a first operation threshold value. Correcting the first operation variable quantity by using the second reference variable quantity to obtain a second operation variable quantity; so as to prevent the change of the capacitance detection value caused by the temperature change from causing interference to the hand-off detection result. And judging the working state of the steering wheel according to the second operation variable quantity so as to determine whether the steering wheel is out of hand.
The steering wheel hands-off detection method is applied to a steering wheel with a capacitance detection unit and a heating unit, in specific implementation, the capacitance detection unit and the heating unit can be two units which are not related to each other, and can also be an integrated unit, and the integrated unit is controlled to respectively point to detection work and heating work at different times. It should be noted that, if the capacitance detection unit and the heating unit are two units that are not related to each other, an additional isolation film needs to be disposed between the two units to prevent the temperature change of the heating unit from affecting the detection result of the capacitance detection unit, but this solution would increase the equipment cost. Fig. 1 is a structural diagram of a steering wheel hands-off detection system according to an embodiment of the present application, and as shown in fig. 1, the system includes: a control unit 1, a first one-way conduction device 2, a second one-way conduction device 3, a detection/heating unit 4 and a corresponding control circuit, wherein the detection/heating unit 4 is a device (such as a metal heating wire) integrating a capacitance detection function and a steering wheel heating function. In one duty cycle, the detection/heating unit 4 performs a heating task and a detection task, respectively, at different times under the control of the control unit 1. In the heating phase of the working cycle, the detection/heating unit 4 performs a heating task, and the steering wheel temperature rises; in the detection stage, the detection/heating unit 4 executes a detection task to detect whether the steering wheel is out of hand, at this time, due to the existence of the first one-way conduction device 2 and the second one-way conduction device 3, when the detection task is executed, the detection/heating unit 4 and the heating control circuit are in an open circuit state, so that the electronic devices and the electric signals in the heating control circuit cannot cause interference on the detection signals acquired by the detection/heating unit 4, and the accuracy of the out-of-hand detection result is ensured. In a specific implementation, the first unidirectional conducting device 2 and the second unidirectional conducting device 3 may be diodes, and may also be other integrated chip control circuits, which is not limited herein. In addition, an AS8579 capacitive sensing chip can be selected to perform capacitive detection, the capacitive sensing chip can detect capacitive parameters with resistance information, 10 detection channels are provided, and the control unit 1 can control the starting data detection function and the reading of the detection result of each detection channel through spi. The control unit 1 acquires data of the detection channel at a cycle of 10 ms.
Fig. 2 is a flowchart of a method for detecting steering wheel hands-off according to an embodiment of the present disclosure, and as shown in fig. 2, the method includes:
s10: a first reference variation of a capacitance detection value of a steering wheel in each detection cycle is acquired.
In specific implementation, a technician sets a detection period according to a steering wheel hands-off detection algorithm, and calculates a first reference variation of a steering wheel detection value in each detection period. The time length of the detection period can be set by a technician according to actual conditions, and is usually 80 ms.
It is understood that the first reference variation amount needs to be acquired by the capacitance detection unit. Specifically, the capacitance detection unit may be a digital detection device, or may be a metal capacitance wire. The capacitance detection unit is arranged on the surface of the steering wheel, when a driver touches the steering wheel, a capacitance detection value can be obtained, and the contact area between the driver and the steering wheel is judged according to the capacitance detection value.
Furthermore, the capacitance detection unit is easily interfered by external environment temperature during working, so that the acquired capacitance detection value is inaccurate, and the hand-off detection result is influenced. In order to solve this problem, the temperature of the steering wheel operating environment may be detected, and the detection result may be corrected according to the temperature.
It can be understood that, in order to ensure data reliability, filtering operation may also be performed on the acquired data.
S11: and calculating a second reference variable quantity in the preset period, wherein the second reference variable quantity is the sum of the first reference variable quantities in the preset period.
It is understood that the preset period is a calculation period pre-selected by a technician, and the preset period includes one or more detection periods. The smaller the detection period included in the preset period, that is, the shorter the preset period, the faster the response speed of the detection of the hands-off of the steering wheel, but if the period is too short, it may be impossible to distinguish between a temperature change and a capacitance change caused by the operation of the steering wheel by the driver.
In a specific implementation, the second reference variation in the preset period is obtained by accumulating the first reference variation in each detection period. And if the second reference variation is smaller than 0, correcting the second reference variation to 0, wherein the reference variation is 0 and represents that the steering wheel is in a completely hands-off state.
S12: and calculating a first operation variation in a preset period, wherein the first operation variation is the sum of first reference variations of which the absolute values are larger than a first operation threshold.
It should be noted that the main causes of the change of the detection result of the capacitance detection unit include: the temperature change of the capacitance detection unit and the operation of a steering wheel (touching the steering wheel or releasing the steering wheel) by a driver; the capacitance change speed caused by temperature change is far less than that caused by operation of a driver, so that whether the steering wheel is out of hand or not is mainly judged by judging whether the driver operates the steering wheel or not in specific implementation. In this embodiment, the capacitance variation caused by the driver operating the steering wheel is obtained as the operation variation, and in order to remove the interference of the temperature variation of the capacitance detection unit itself on the detection result, an amount greater than the first operation threshold value in the operation variation needs to be screened out and summed to obtain the first operation variation. It will be appreciated that the first operational threshold may be predetermined by a skilled person or may be calculated based on the actual situation. In the present embodiment, in order to prevent the temperature change from interfering with the detection result, the first operation threshold is a value determined according to the first reference change amount. When the absolute value of the first reference change amount is larger than the first operation threshold, indicating that the change is caused by the driver operating the steering wheel; when the first reference variation amount is not greater than the first operation threshold, it indicates that the variation is due to a temperature variation of the temperature detection unit.
S13: correcting the first operation variable quantity by using the second reference variable quantity to obtain a second operation variable quantity;
furthermore, the first operation threshold may largely represent the operation condition of the driver on the steering wheel, but when the capacitance detection unit is in the rapid temperature change process, if the driver continuously touches or releases the steering wheel for many times, or moves both hands on the steering wheel with an incompletely-contacted holding posture for many times, the change of the detection result caused by the temperature of the heating wire may be gradually superimposed on the first operation variation amount due to the simultaneous occurrence of the change of the detection result caused by the driver operating the steering wheel, and when the change is accumulated for a period of time, the first operation variation amount will be distorted, and it is not possible to accurately represent whether the steering wheel is in the hands-off state. Therefore, the first operation variation amount also needs to be corrected by the second reference variation amount to obtain the second operation variation amount.
In a specific implementation, the first operation variation amount may be corrected by setting the operation threshold in stages. It is understood that two or more operating thresholds may be provided, and are not limited herein.
In the present embodiment, a case where two levels of operation thresholds (second operation threshold, third operation threshold) are set will be described as an example of a scheme.
If the first operation variation is larger than the difference between the second reference variation and the second operation threshold, the second operation variation is set as the difference between the second reference variation and the second operation threshold. When the second reference variation is larger than the third operation threshold, if the first operation variation is smaller than the difference between the second reference variation and the third operation threshold, the second operation variation is set as the difference between the second reference variation and the third operation threshold. If the first operation variation is larger than the difference between the second reference variation and the second operation threshold, setting the second operation variation as the difference between the second reference variation and the second operation threshold; wherein the second operational threshold is less than the third operational threshold.
S14: and judging the working state of the steering wheel according to the second operation variable quantity.
And judging the working state of the steering wheel according to the corrected second operation variable quantity, if the second operation variable quantity is larger than the preset variable quantity, indicating that the steering wheel is not released, otherwise, indicating that the steering wheel is released.
The steering wheel hands-off detection method provided by the application comprises the following steps: the method comprises the steps of obtaining first reference variable quantity of a capacitance detection value of a steering wheel in each detection period, and calculating second reference variable quantity in a preset period and first operation variable quantity in the preset period so as to determine whether the steering wheel is out of hand according to the change situation of the capacitance detection value at the steering wheel, wherein the second reference variable quantity is the sum of the first reference variable quantities in the preset period, and the first operation variable quantity is the sum of the first reference variable quantities with absolute values larger than a first operation threshold value. Correcting the first operation variable quantity by using the second reference variable quantity to obtain a second operation variable quantity; so as to prevent the capacitance detection value change caused by the temperature change from interfering the hand-off detection result. And judging the working state of the steering wheel according to the second operation variable quantity so as to determine whether the steering wheel is out of hand. Therefore, according to the scheme provided by the application, the first operation variable quantity is corrected, so that the interference of temperature on capacitance detection is prevented, and the accuracy of the steering wheel hands-off detection is improved.
In a specific implementation, in order to avoid the influence of the ambient temperature on the capacitance detection result, the capacitance change caused by the temperature change needs to be removed from the capacitance change amount.
On the basis of the above-described embodiment, acquiring the first reference variation amount of the capacitance detection value of the steering wheel in each detection cycle includes:
acquiring a steering wheel capacitance measurement value and an environment capacitance measurement value;
a first baseline variation is calculated from the steering wheel capacitance measurement and the ambient capacitance measurement.
It is understood that the capacitance detection unit has at least two detection channels, one of which is connected to the steering wheel for obtaining a capacitance change at the steering wheel, i.e. a steering wheel capacitance measurement, and the other of which is exposed to the environment near the steering wheel for obtaining a capacitance change caused by a change in the ambient temperature, i.e. an ambient capacitance measurement. Because the steering wheel detection channel is connected with a heating wire load, and the environment detection channel is suspended, the capacitance measured value of the steering wheel is certainly larger than that of the environment. And subtracting the environmental capacitance measurement value from the steering wheel capacitance measurement value to obtain a first reference variation. In the driving process, the first reference variable quantity is not influenced by the ambient temperature, and the accuracy of the steering wheel hands-off detection can be improved.
In this embodiment, the first reference variation is calculated by the steering wheel capacitance measurement value and the environment capacitance measurement value, so as to eliminate the interference of the environment temperature on the capacitance detection result and improve the reliability of the steering wheel hands-off detection method.
In a specific implementation, when the capacitance detection unit and the heating unit are both metal heating wires, the capacitance detection value is also influenced by the material of the metal heating wires, the temperature of the metal heating wires, the material of the surface of the steering wheel and the like. Wherein, the temperature of the metal heating wire has a large influence on the detection result.
In order to solve the problem, on the basis of the above embodiment, after the step of calculating the first reference variation based on the steering wheel capacitance measurement value and the environment capacitance measurement value, the method further includes:
acquiring a current heating unit temperature value;
and performing temperature compensation operation on the first reference variable quantity according to the current heating unit temperature value.
In order to eliminate the capacitance detection data change caused by the temperature change of the heating unit (heating wire), a temperature compensation algorithm is introduced in the embodiment, and the temperature compensation is performed on the first reference change amount by detecting the temperature of the heating unit.
In specific implementation, the temperature of the heating unit is acquired through the temperature acquisition unit, wherein the temperature acquisition unit can be a device in a heating system or an additionally arranged temperature sensor, and the former scheme can reduce equipment cost.
Generally, the heating unit is embedded with an NTC thermistor, and the temperature of the heating unit can be calculated by the voltage division of the resistor and the NTC thermistor in the temperature monitoring circuit. Specifically, since the resistance value of the NTC thermistor is in a linear relationship with the temperature, and the divided voltage value is also in a linear relationship with the temperature, the corresponding temperature value can be calculated by detecting the divided voltage value of the NTC thermistor and by the linear relationship between the resistance value and the temperature.
In specific implementation, detection results corresponding to different temperatures when the steering wheel is in the hands-off state are determined in advance through an experimental mode, and therefore the influence of the temperatures on the detection results is calculated. The capacitance variation value of the heating wire in the hands-off state at-40 ℃, 0 ℃, 25 ℃, 50 ℃ and 85 ℃ is usually detected, the detection result and the temperature basically have a linear relation, namely the capacitance variation value under the unit temperature variation is a fixed value, the unit temperature compensation value is calculated by the method, and the unit temperature compensation value is fixed for the steering wheel with the same model.
During the calculation, the capacitance reference value at the standard temperature is also required to be determined. A calibration station can be added to a steering wheel production line, and the production line is controlled to have a constant temperature of 25 ℃. And arranging a steering wheel at the calibration station, connecting the controller with the steering wheel, sending a command through a controller communication bus to enable the controller to record the detected capacitance detection value as a capacitance reference value and store the capacitance reference value in a data storage area, and recording a mark for completing calibration in the data storage area.
After the capacitance reference value and the unit temperature compensation value are obtained, the capacitance reference value in the steering wheel hands-off state at the current temperature can be determined, and the capacitance reference value is equal to the capacitance reference value + (the current heating unit temperature value is minus 25 ℃) equal to the unit temperature compensation value. And acquiring a first reference variable quantity in the detection period according to the capacitance reference value, so that the interference of the temperature of the heating unit on the capacitance detection value can be eliminated.
In this embodiment, when the capacitance detection unit and the heating unit are both metal heating wires, the capacitance reference value at the current temperature is obtained by detecting the temperature and the temperature compensation value of the heating unit, so that the interference of the temperature of the heating wires on the detection result is eliminated, and the reliability and the accuracy of the steering wheel hands-off detection method are improved.
In specific implementation, in the process of measuring the capacitance by the capacitance detection unit, the capacitance value detected may be inaccurate due to other disturbances, and in order to improve the reliability of the capacitance detection value and thus improve the accuracy of the steering wheel hands-off detection result, the obtained measurement value may be filtered.
On the basis of the above embodiment, after the step of obtaining the steering wheel capacitance measurement value and the environmental capacitance measurement value, the method further includes: a filtering operation is performed on the steering wheel capacitance measurement and the ambient capacitance measurement.
The filtering algorithm used herein is not limited, and may be a median filtering method, a limiting filtering method, an arithmetic mean filtering method, a reverse-push mean filtering method, or the like.
In this embodiment, a median average value filtering method is selected to perform filtering operation on the obtained steering wheel capacitance measurement value and the obtained environment capacitance measurement value. In a specific implementation, a number of (e.g., 12) acquired measurements are grouped into a group, each group of measurements is placed in a queue, the maximum and minimum values are deleted, and the average of the remaining measurements is calculated to implement a filtering operation on the steering wheel capacitance measurements and the ambient capacitance measurements.
Furthermore, a filter circuit can be added in the steering wheel capacitance measuring circuit and the environment capacitance measuring circuit, so that the accuracy of the measured value is further improved.
In this embodiment, after the steering wheel capacitance measurement and the ambient capacitance measurement are obtained, a filtering operation is performed on the steering wheel capacitance measurement and the ambient capacitance measurement. The influence of circuit disturbance on a capacitance measurement value in a capacitance measurement process is prevented, and the accuracy and the reliability of a steering wheel hands-off detection result are improved.
In a specific implementation, when the capacitance detecting unit is in a rapid temperature change process, if a driver continuously touches or releases the steering wheel for multiple times or moves two hands on the steering wheel with an incomplete contact gripping posture for multiple times, a detection result change caused by the temperature of the heating wire is gradually superimposed on the first operation variation because of simultaneous occurrence of the detection result change caused by the operation of the steering wheel by the driver, so that the first operation variation is distorted.
In order to solve this problem, the first operation variation amount needs to be corrected by the second reference variation amount to obtain the second operation variation amount. Specifically, in the scheme provided by the application, the first operation variation is corrected by setting the classification operation threshold and according to the classification operation threshold. It will be appreciated that two levels of operating thresholds may be provided, as may multiple levels of operating thresholds. In the present embodiment, the correction operation is described by taking a two-stage operation threshold as an example.
On the basis of the above-described embodiments,
if the first operation variation is larger than the difference between the second reference variation and the second operation threshold, setting the second operation variation as the difference between the second reference variation and the second operation threshold;
when the second reference variation is larger than the third operation threshold, if the first operation variation is smaller than the difference between the second reference variation and the third operation threshold, setting the second operation variation as the difference between the second reference variation and the third operation threshold;
if the first operation variation is larger than the difference between the second reference variation and the second operation threshold, the second operation variation is set as the difference between the second reference variation and the second operation threshold. Through the correction of the first operation variable quantity, the value of the second operation variable quantity is smaller than or equal to the difference between the second reference variable quantity and the second operation threshold and is larger than or equal to the difference between the second reference variable quantity and the second operation threshold, so that the correction of the first operation variable quantity is realized under the condition that the detection result is inaccurate because a driver slowly touches a steering wheel. When the driver slowly touches the steering wheel, the capacitance change speed caused by the operation and the capacitance change speed caused by the heating are in the same order of magnitude, and in order to prevent the capacitance change amount caused by the temperature of the heating wire from being superposed on the first operation change amount, when the first operation change amount is smaller than the difference between the second reference change amount and the third operation threshold value, the second operation change amount is set as the difference between the second reference change amount and the third operation threshold value. The operation of the driver on the steering wheel can be accurately reflected by the first operation variable quantity. Wherein the second operational threshold is less than the third operational threshold.
In the embodiment, the first operation variable quantity is corrected by setting the grading operation threshold value, so that the change of the capacitance detection result caused by the temperature of the heating wire is prevented from being superposed on the first operation variable quantity, the first operation variable quantity is prevented from being distorted, and the accuracy and the reliability of the steering wheel hands-off detection are improved.
In the process of driving the vehicle by a driver, because the vehicle is high in driving speed and the detection and the reminding have certain hysteresis, danger can not be avoided when the steering wheel is determined to be out of hand and the reminding is carried out.
To solve this problem, on the basis of the above-described embodiment, determining the operating state of the steering wheel according to the second operation variation amount includes:
the working state comprises the following steps: a strong touch state, a weak touch state and a hands-off state.
If the second operation variable quantity is larger than the first touch threshold value, determining that the steering wheel is in a strong touch state;
if the second operation variation is not larger than the first touch threshold and larger than the second touch threshold, determining that the steering wheel is in a weak touch state;
and if the second operation variation is not larger than a second touch threshold, determining that the steering wheel is in the hands-off state, wherein the first touch threshold is larger than the second touch threshold.
It can be understood that a multi-level touch threshold value can be set, and the working state of the steering wheel can be detected more accurately. The more touch thresholds are set, the more sensitive the detection structure is, but the calculation resource consumption will increase.
In specific implementation, when the steering wheel is in a strong collision state, a prompt does not need to be sent to a driver; when the steering wheel is in a weak collision state, a warning is sent to a driver through a warning lamp or an alarm or a display screen; when the steering wheel is in the hands-off state, the vehicle can be controlled to slow down and the like besides reminding a driver, so that the safety of the driver is ensured.
It can be understood that the initial values of the first operation variation and the second operation variation after the system is powered on are 0, and the state immediately after power on is defined as the initial state because the driver may or may not touch the steering wheel with his/her hand before power on. When the driver operates the steering wheel (i.e., the driver touches the steering wheel and releases the steering wheel), the second operation variation can be obtained and the operating state of the steering wheel can be determined according to the second operation variation.
In the embodiment, the working state of the steering wheel is accurately determined by setting a multi-level touch threshold value, so that corresponding operation is taken to ensure the safety of a driver.
In specific implementation, in order to improve the accuracy of judging the working state of the steering wheel and prevent errors during switching of the working state of the steering wheel, hysteresis parameters can be set for touch thresholds at all levels, and the hysteresis parameters can be reasonably set according to actual operation changes and the relationship between the actual operation changes and the area of the hand touching the steering wheel. For example, when the first touch threshold is 90 and the second touch threshold is 40, the first hysteresis parameter and the second hysteresis parameter are both set to 20.
On the basis of the above embodiment, after the step of determining the operating state of the steering wheel according to the second operation variation, the method further includes:
setting a first hysteresis parameter and a second hysteresis parameter;
when the steering wheel is in a strong touch state or a weak touch state, judging whether the second operation variation is smaller than the difference between the second touch threshold and the first hysteresis parameter;
if the current time is less than the preset time, setting the working state as a hands-off state;
when the working state is a strong touch state, if the second operation variation is smaller than the difference between the first touch threshold and the second hysteresis parameter and the second operation variation is not smaller than the difference between the second touch threshold and the first hysteresis parameter;
if yes, the working state is set to be a weak collision state.
Further, to enhance the stability of the switching of the operating states, a shake elimination time may be set for the switching of the operating states, for example, when the current operating state is a soft touch state, and when the operating value is greater than the first touch threshold value and the shake elimination time continues to exceed the shake elimination time, the current operating state is switched to a hard touch state, specifically, the shake elimination time for switching from the initial state to the other operating state is 40ms, and the shake elimination time between the other operating states is 100 ms.
In addition, a zero drift threshold and a zero drift correction time threshold may be set, and when the first operation variation or the second operation variation is within the zero drift threshold range and the duration time reaches the zero drift correction time threshold, the first operation variation or the second operation variation is corrected to 0, and the first reference variation and the second reference variation are corrected to 0.
In the above embodiments, the steering wheel hands-off detection method is described in detail, and the present application also provides embodiments corresponding to the steering wheel hands-off detection device. It should be noted that the present application describes the embodiments of the apparatus portion from two perspectives, one from the perspective of the function module and the other from the perspective of the hardware.
Fig. 3 is a structural diagram of a steering wheel hands-off detection device according to an embodiment of the present application, and as shown in fig. 3, the device includes:
an obtaining module 10, configured to obtain a first reference variation of a capacitance detection value of a steering wheel in each detection period;
the first calculating module 11 is configured to calculate a second reference variation in the preset period, where the second reference variation is a sum of first reference variations in the preset period;
the second calculating module 12 is configured to calculate a first operation variation in a preset period, where the first operation variation is a sum of first reference variations of which absolute values are greater than a first operation threshold;
the correcting module 13 is configured to correct the first operation variation by using the second reference variation to obtain a second operation variation;
and the judging module 14 is used for judging the working state of the steering wheel according to the second operation variation.
Since the embodiments of the apparatus portion and the method portion correspond to each other, please refer to the description of the embodiments of the method portion for the embodiments of the apparatus portion, which is not repeated here.
In this embodiment, there is provided a steering wheel hands-off detection apparatus, the apparatus including: the method comprises the steps of obtaining first reference variable quantity of a capacitance detection value of a steering wheel in each detection period, and calculating second reference variable quantity in a preset period and first operation variable quantity in the preset period so as to determine whether the steering wheel is out of hand according to the change situation of the capacitance detection value at the steering wheel, wherein the second reference variable quantity is the sum of the first reference variable quantities in the preset period, and the first operation variable quantity is the sum of the first reference variable quantities with absolute values larger than a first operation threshold value. Correcting the first operation variable quantity by using the second reference variable quantity to obtain a second operation variable quantity; so as to prevent the capacitance detection value change caused by the temperature change from interfering the hand-off detection result. And judging the working state of the steering wheel according to the second operation variable quantity so as to determine whether the steering wheel is out of hand. Therefore, according to the scheme provided by the application, the first operation variable quantity is corrected, so that the interference of temperature on capacitance detection is prevented, and the accuracy of the steering wheel hands-off detection is improved.
Fig. 4 is a structural diagram of another steering wheel hands-off detection device according to an embodiment of the present application, and as shown in fig. 4, the steering wheel hands-off detection device includes: a memory 20 for storing a computer program;
the processor 21 is configured to implement the steps of the method for acquiring the first reference variation, the second reference variation and the first operation variation as described in the above embodiments when executing the computer program.
The steering wheel hands-off detection device provided by the embodiment may include, but is not limited to, a smart phone, a tablet computer, a notebook computer, a desktop computer, or the like.
The processor 21 may include one or more processing cores, such as a 4-core processor, an 8-core processor, and the like. The Processor 21 may be implemented in hardware using at least one of a Digital Signal Processor (DSP), a Field-Programmable Gate Array (FPGA), and a Programmable Logic Array (PLA). The processor 21 may also include a main processor and a coprocessor, where the main processor is a processor for Processing data in an awake state, and is also called a Central Processing Unit (CPU); a coprocessor is a low power processor for processing data in a standby state. In some embodiments, the processor 21 may be integrated with a Graphics Processing Unit (GPU) which is responsible for rendering and drawing the content required to be displayed by the display screen. In some embodiments, the processor 21 may further include an Artificial Intelligence (AI) processor for processing computational operations related to machine learning.
The memory 20 may include one or more computer-readable storage media, which may be non-transitory. Memory 20 may also include high speed random access memory, as well as non-volatile memory, such as one or more magnetic disk storage devices, flash memory storage devices. In this embodiment, the memory 20 is at least used for storing a computer program 201, wherein after being loaded and executed by the processor 21, the computer program is capable of implementing relevant steps of the steering wheel hands-off detection method disclosed in any one of the foregoing embodiments. In addition, the resources stored in the memory 20 may also include an operating system 202, data 203, and the like, and the storage manner may be a transient storage manner or a permanent storage manner. Operating system 202 may include, among others, Windows, Unix, Linux, and the like. The data 203 may include, but is not limited to, a first reference change amount, a second reference change amount, a first operation change amount, and the like.
In some embodiments, the steering wheel hands-off detection device may further include a display 22, an input/output interface 23, a communication interface 24, a power source 25, and a communication bus 26.
Those skilled in the art will appreciate that the configuration shown in FIG. 4 does not constitute a limitation of the steering wheel hands-off detection arrangement and may include more or fewer components than those shown.
The steering wheel hands-off detection device provided by the embodiment of the application comprises a memory and a processor, wherein when the processor executes a program stored in the memory, the following method can be realized:
acquiring a first reference variable quantity of a capacitance detection value of a steering wheel in each detection period;
calculating a second reference variable quantity in the preset period, wherein the second reference variable quantity is the sum of all first reference variable quantities in the preset period;
calculating a first operation variable quantity in a preset period, wherein the first operation variable quantity is the sum of various first reference variable quantities of which the absolute values are greater than a first operation threshold value;
correcting the first operation variable quantity by using the second reference variable quantity to obtain a second operation variable quantity;
and judging the working state of the steering wheel according to the second operation variable quantity.
Finally, the application also provides a corresponding embodiment of the computer readable storage medium. The computer-readable storage medium has stored thereon a computer program which, when being executed by a processor, carries out the steps as set forth in the above-mentioned method embodiments.
It is to be understood that if the method in the above embodiments is implemented in the form of software functional units and sold or used as a stand-alone product, it can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application, which are essential or part of the prior art, or all or part of the technical solutions may be embodied in the form of a software product, which is stored in a storage medium and executes all or part of the steps of the methods described in the embodiments of the present application. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a portable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.
The steering wheel hands-off detection method, device and medium provided by the application are described in detail above. The embodiments are described in a progressive manner in the specification, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description. It should be noted that, for those skilled in the art, without departing from the principle of the present application, the present application can also make several improvements and modifications, and those improvements and modifications also fall into the protection scope of the claims of the present application.
It is further noted that, in the present specification, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
Claims (10)
1. A steering wheel hands-off detection method is characterized by comprising the following steps:
acquiring a first reference variable quantity of a capacitance detection value of a steering wheel in each detection period;
calculating a second reference variation in a preset period, wherein the second reference variation is the sum of all the first reference variations in the preset period;
calculating a first operation variation in a preset period, wherein the first operation variation is the sum of each first reference variation with an absolute value larger than a first operation threshold;
correcting the first operation variable quantity by using the second reference variable quantity to obtain a second operation variable quantity;
and judging the working state of the steering wheel according to the second operation variable quantity.
2. The method of detecting a steering wheel release according to claim 1, wherein the obtaining a first reference change amount of the capacitance detection value of the steering wheel in each detection cycle includes:
acquiring a steering wheel capacitance measurement value and an environment capacitance measurement value;
calculating the first baseline variation from the steering wheel capacitance measurement and the ambient capacitance measurement.
3. The method of claim 2, wherein the step of obtaining a steering wheel capacitance measurement and an ambient capacitance measurement is followed by the step of:
performing a filtering operation on the steering wheel capacitance measurement and the ambient capacitance measurement.
4. The method of claim 2, wherein the step of calculating the first baseline variation from the steering wheel capacitance measurement and the ambient capacitance measurement further comprises:
acquiring a current heating unit temperature value;
and performing temperature compensation operation on the first reference variable quantity according to the current heating unit temperature value.
5. The steering wheel hands-off detection method according to claim 1, wherein the correcting the first operation variation amount using the second reference variation amount to obtain a second operation variation amount includes:
setting the second operation variation as a difference between the second reference variation and the second operation threshold if the first operation variation is larger than the difference between the second reference variation and the second operation threshold;
when the second reference variation is larger than the third operation threshold, if the first operation variation is smaller than the difference between the second reference variation and the third operation threshold, setting the second operation variation as the difference between the second reference variation and the third operation threshold;
setting the second operation variation as a difference between the second reference variation and the second operation threshold if the first operation variation is larger than the difference between the second reference variation and the second operation threshold;
wherein the second operational threshold is less than the third operational threshold.
6. The steering wheel hands-off detection method according to claim 1, wherein the determining the operating state of the steering wheel according to the second operation variation amount includes:
the working state comprises the following steps: a strong collision state, a weak collision state and a hands-off state;
if the second operation variable quantity is larger than a first touch threshold value, determining that the steering wheel is in the strong touch state;
if the second operation variation is not larger than the first touch threshold and larger than a second touch threshold, determining that the steering wheel is in the weak touch state;
and if the second operation variation is not larger than the second touch threshold, determining that the steering wheel is in the hands-off state.
7. The method for detecting a steering wheel release according to claim 6, further comprising, after the step of determining the operating state of the steering wheel based on the second operation variation amount:
setting a first hysteresis parameter and a second hysteresis parameter;
when the steering wheel is in the strong collision state or the weak collision state, judging whether the second operation variation is smaller than the difference between the second touch threshold and the first hysteresis parameter;
if the working state is smaller than the preset working state, setting the working state as a hands-off state;
when the working state is in the strong touch state, judging whether the second operation variation is smaller than the difference between the first touch threshold and the second hysteresis parameter or not, and the second operation variation is not smaller than the difference between the second touch threshold and the first hysteresis parameter;
and if so, setting the working state as a weak collision state.
8. A steering wheel hands-off detection device, comprising:
the acquisition module is used for acquiring a first reference variable quantity of a capacitance detection value of the steering wheel in each detection period;
the first calculation module is used for calculating a second reference variation in a preset period, and the second reference variation is the sum of all the first reference variations in the preset period;
the second calculation module is used for calculating a first operation variable quantity in a preset period, wherein the first operation variable quantity is the sum of all first reference variable quantities of which the absolute values are greater than a first operation threshold value;
the correction module is used for correcting the first operation variable quantity by using the second reference variable quantity so as to obtain a second operation variable quantity;
and the judging module is used for judging the working state of the steering wheel according to the second operation variable quantity.
9. A steering wheel hands-off detection device comprising a memory for storing a computer program;
a processor for implementing the steps of the steering wheel hands-off detection method according to any of claims 1 to 7 when executing the computer program.
10. A computer-readable storage medium, characterized in that a computer program is stored thereon, which computer program, when being executed by a processor, carries out the steps of the steering wheel hands-off detection method according to any one of claims 1 to 7.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114852092A (en) * | 2022-07-04 | 2022-08-05 | 小米汽车科技有限公司 | Steering wheel hands-off detection method and device, readable storage medium and vehicle |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114852092A (en) * | 2022-07-04 | 2022-08-05 | 小米汽车科技有限公司 | Steering wheel hands-off detection method and device, readable storage medium and vehicle |
| CN114852092B (en) * | 2022-07-04 | 2022-09-30 | 小米汽车科技有限公司 | Steering wheel hands-off detection method and device, readable storage medium and vehicle |
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