CN217435702U - Steering wheel hands-off detection circuit and system - Google Patents
Steering wheel hands-off detection circuit and system Download PDFInfo
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- CN217435702U CN217435702U CN202220592352.0U CN202220592352U CN217435702U CN 217435702 U CN217435702 U CN 217435702U CN 202220592352 U CN202220592352 U CN 202220592352U CN 217435702 U CN217435702 U CN 217435702U
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Abstract
The utility model discloses a steering wheel takes off one's hand detection circuitry and system, include: the device comprises a control unit, a first one-way conduction device, a second one-way conduction device and a detection/heating unit. The first one-way conduction device is connected with the control unit and the detection/heating unit; the second one-way conduction device is connected with the control unit and the detection/heating unit; the first one-way conduction device and the second one-way conduction device have a one-way conduction characteristic, when the detection/heating unit works, the electric signal is prevented from flowing into the heating control circuit, and the heating control circuit is prevented from influencing the electric signal acquired by the detection/heating unit. The control unit controls the detection/heating unit to respectively execute tasks of acquiring detection signals and heating at different time so as to achieve the purposes of heating the steering wheel and detecting the hands falling off. The detection/heating unit and the heating control circuit which are multiplexed are connected through the one-way conduction device, and the cost of the detection system is reduced on the basis of obtaining accurate detection signals.
Description
Technical Field
The utility model relates to an automobile control field especially relates to a steering wheel takes off hand detection circuitry and system.
Background
In order to ensure the safe driving of the automobile, whether the steering wheel is out of hand needs to be detected during the driving process of the automobile. At present, a common capacitive detection membrane is used for detecting whether the steering wheel is out of hand, and when the strength of an electric signal of the detection membrane is lower than a threshold value, the condition that the two hands of a driver leave the steering wheel is indicated, namely the steering wheel is out of hand. However, the surface of the steering wheel is provided with a heating film for raising the temperature, and the heating film needs to be heated by a heating control circuit. This causes the control signal and the coupling capacitance in the heating control circuit to affect the hands-off detection circuit connected to the capacitive detection film, which results in the failure of normal hands-off detection.
In order to avoid the interference of the heating unit to the detection signal, a shielding film is usually used to isolate the detection unit from the heating unit, but this solution requires the use of an additional shielding film, which increases the production cost.
Therefore, how to provide a low-cost steering wheel hands-off detection circuit to prevent the heating control circuit from influencing the hands-off detection result is a problem that needs to be solved by those skilled in the art.
SUMMERY OF THE UTILITY MODEL
The utility model aims at providing a steering wheel takes off hand detection circuitry and system.
In order to solve the above technical problem, the present application provides a steering wheel hands-off detection circuit, which includes:
the device comprises a control unit, a first one-way conduction device, a second one-way conduction device and a detection/heating unit, wherein the detection/heating unit is an integrated unit integrating a capacitance detection function and a heating function;
the first end of the first one-way conduction device is connected with the control unit, and the second end of the first one-way conduction device is connected with the detection/heating unit;
the second end of the second unidirectional conduction device is connected with the control unit, and the first end of the second unidirectional conduction device is connected with the detection/heating unit; the control unit is further connected with the second end of the first one-way conduction device and used for controlling the detection/heating unit to respectively execute tasks of acquiring a detection signal and heating at different time so as to achieve the purposes of heating the steering wheel and judging whether the steering wheel is out of hand or not according to the detection signal sent by the detection/heating unit.
Preferably, the device also comprises a driving unit, a detection control unit and a switch control unit;
the first end of the driving unit is connected with the control unit, and the second end of the driving unit is connected with the first end of the first unidirectional device;
the first end of the detection control unit is connected with the control unit, and the second end of the detection control unit is connected with the detection/heating unit;
and the first end of the switch control unit is connected with the second end of the second one-way conduction device, the second end of the switch control unit is grounded, and the control end of the switch control unit is connected with the control unit.
Preferably, the detecting/heating unit is a metal heating wire disposed on a surface of the steering wheel.
Preferably, the device further comprises a back-voltage circuit, wherein the back-voltage circuit comprises a back-voltage power supply, a first resistor and a second resistor;
the first end of the first resistor is grounded, the second end of the first resistor is connected with the first end of the second resistor, and the second end of the second resistor is connected with the back voltage power supply;
and the common end of the first resistor and the second resistor is used as the output end of the counter voltage circuit and is connected with the second end of the second one-way conduction device.
Preferably, the first unidirectional conducting device and the second unidirectional conducting device are both diodes.
Preferably, the switch control unit is an MOS transistor.
Preferably, the driving unit is a PWM driving unit.
Preferably, the protection circuit further comprises a protection resistor, a first end of the protection resistor is connected with a first end of the first conducting device, and a second end of the protection resistor is grounded.
Preferably, the detection control unit is a capacitance sensor.
In order to solve the technical problem, the present application further provides a steering wheel hands-off detection system, including the steering wheel hands-off detection circuit.
The utility model provides a steering wheel takes off one's hand detection circuitry includes: the device comprises a control unit, a first one-way conduction device, a second one-way conduction device and a detection/heating unit. The first end of the first one-way conduction device is connected with the control unit, and the second end of the first one-way conduction device is connected with the detection/heating unit; the second end of the second one-way conduction device is connected with the control unit, and the first end of the second one-way conduction device is connected with the detection/heating unit; the first one-way conduction device and the second one-way conduction device have a one-way conduction characteristic, the heating unit can work normally under the control of the control unit, and when the detection/heating unit works, the electric signal is prevented from flowing into the heating control circuit, and the heating control circuit is prevented from influencing the electric signal acquired by the detection/heating unit. The control unit is also connected with the second end of the first one-way conduction device and used for controlling the detection/heating unit to respectively execute tasks of acquiring a detection signal and heating at different time so as to achieve the purposes of heating the steering wheel, acquiring the detection signal sent by the detection/heating unit and judging whether the steering wheel is out of hand. Therefore, the heating control circuit signal is prevented from interfering the detection signal through the one-way conduction device, multiplexing of the detection/heating unit and the heating control unit is achieved, and the cost of the detection system is reduced on the basis of ensuring the accuracy of the detection signal and the accuracy of the hands-off detection.
Furthermore, the utility model also provides a steering wheel hands-free detection system, including above-mentioned steering wheel hands-free detection circuitry, the effect is the same as above.
Drawings
In order to illustrate the embodiments of the present invention more clearly, the drawings that are needed in 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 invention, and it is obvious to those skilled in the art that other drawings can be obtained based on these drawings without inventive work.
Fig. 1 is a structural diagram of a steering wheel hands-off detection circuit according to an embodiment of the present disclosure;
fig. 2 is a flowchart of a control method of a steering wheel hands-off detection circuit according to an embodiment of the present disclosure;
fig. 3 is a structural diagram of a detection control unit according to an embodiment of the present application;
fig. 4 is a block diagram of another steering wheel hands-off detection circuit provided in an embodiment of the present application;
fig. 5 is a structural diagram of a driving unit according to an embodiment of the present application;
fig. 6 is a structural diagram of a switch control unit according to an embodiment of the present disclosure;
the reference numbers are as follows: the device comprises a control unit 1, a first one-way conduction device 2, a second one-way conduction device 3, a detection/heating unit 4, a driving unit 5, a detection control unit 6 and a switch control unit 7.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, the ordinary skilled in the art can obtain all other embodiments without creative work, which all belong to the protection scope of the present invention.
The core of the utility model is to provide a steering wheel takes off hand detection circuitry and system to prevent the heating circuit to the interference of taking off the hand detection, thereby more accurate judgement steering wheel is taken off the hand or not.
In order to make the technical field better understand the solution of the present invention, the following detailed description of the present invention is provided with reference to the accompanying drawings and the detailed description.
In an automobile driving scene, a heating unit for heating and a detection unit for detecting whether the steering wheel is out of hand are arranged on the surface of the steering wheel, and in order to reduce hardware cost, a detection/heating unit integrating a heating function and a capacitance detection function is selected to execute a steering wheel heating task and a capacitance detection task. In a specific implementation, the detection/heating unit performs the heating task and the detection task respectively at different times under the control of the control unit. And the heating control circuit and the detection control circuit multiplex part of circuit elements. But this can result in the heating control circuit and the heating control signal in the circuit affecting the accuracy of the hands-off detection. The steering wheel hands-off detection circuit provided by the application isolates the detection circuit and the heating control circuit through the one-way conduction device; in one working cycle, the detection/heating unit respectively executes a heating task and a detection task at different times under the control of the control unit. In the heating stage of the working cycle, the detection/heating unit executes a heating task, and the temperature of the steering wheel rises; in the detection stage, the detection/heating unit executes a detection task to detect whether the steering wheel is out of hand, at the moment, 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 and the heating control circuit are in an open circuit state, so that electronic devices and electric signals in the heating control circuit cannot cause interference on detection signals acquired by the detection/heating unit, and the accuracy of the out-of-hand detection result is ensured.
The detection/heating unit 4 may include a capacitance detection device and a heating device, and controls the capacitance detection device to operate during a detection period and controls the heating device to operate during a heating period; the capacitance detection and heating can also be realized by multiplexing the metal heating wires. In order to reduce the hardware cost of the hands-off detection circuit, the latter scheme is selected in the embodiment.
Fig. 1 is a structural diagram of a steering wheel hands-off detection circuit according to an embodiment of the present application, and as shown in fig. 1, the steering wheel hands-off detection circuit includes:
the device comprises a control unit 1, a first one-way conduction device 2, a second one-way conduction device 3 and a detection/heating unit 4, wherein the detection/heating unit 4 is an integrated unit integrating a capacitance detection function and a heating function;
the first end of the first one-way conduction device 2 is connected with the control unit 1, and the second end of the first one-way conduction device 2 is connected with the detection/heating unit 4;
the second end of the second unidirectional conduction device 3 is connected with the control unit 1, and the first end of the second unidirectional conduction device 3 is connected with the detection/heating unit 4;
the control unit 1 is further connected to the second end of the first unidirectional conductive device 2, and is configured to control the detection/heating unit 4 to perform tasks of acquiring a detection signal and heating at different times, so as to achieve the purposes of heating a steering wheel and determining whether the steering wheel is out of hand according to the detection signal sent by the detection/heating unit. In specific implementation, the first unidirectional conducting device 2 and the second unidirectional conducting device 3 provided in this embodiment may be diodes, or may be other devices or apparatuses capable of controlling unidirectional conduction of a circuit, such as a single chip, for example, and are not limited herein. And the second end of the second one-way conduction device is connected with the back-pressure circuit and is used for acquiring a back-pressure signal.
In a specific implementation, each working cycle of the steering wheel hands-off detection circuit includes a heating phase and a detection phase, and the detection/heating unit 4 includes a detection device (such as a capacitance sensor or a metal heating wire) and a detection control unit arranged at the steering wheel, wherein the detection control unit may be a control unit in the detection system or a separately arranged processor; the former scheme can further reduce the cost of the detection system, and the latter scheme can improve the stability and reliability of the system and prevent the system from being crashed after the control unit fails. The control circuit for executing the detection task and the control circuit for executing the heating task share part of the circuit devices and lines. The working process of the hands-off detection circuit is as follows: when in the heating phase, the detection/heating unit 4 operates under the control of the control unit 1 to heat the steering wheel; when the steering wheel is in the detection stage, the control unit 1 controls the detection/heating unit 4 to obtain a detection signal according to the detection result and sends the detection signal to the control unit 1, and because the connection point of the control unit 1 and the detection/heating unit 4 is located at the second end of the first one-way conduction device 2, the current signal in the heating control circuit and the coupling capacitor generated by the circuit element cannot cause interference on the detection signal generated by the detection device, and the detection control unit judges whether the steering wheel is out of hand according to the detection signal.
Fig. 2 is a flowchart of a control method of a steering wheel hands-off detection circuit according to an embodiment of the present application, and as shown in fig. 2, the method includes:
s10: controlling the detection/heating unit 4 to work so as to collect detection signals and heat the steering wheel; the control unit controls the detection/heating unit to respectively execute tasks of acquiring detection signals and heating at different times.
In specific implementation, the control unit 1 controls the detection/heating unit 4 to execute the detection task and the heating task in a time-sharing manner, the time for executing the detection task and the time for executing the heating task in each working cycle can be preset by a manager, usually, each working cycle is 10ms, and the control unit 1 can also calculate according to the current temperature and the target temperature, and the latter scheme can significantly improve the heating efficiency and the detection efficiency.
When the detection/heating unit 4 executes a heating task, the control unit 1 controls the detection/heating unit 4 to work through the PWM control signal, and after the detection/heating unit 4 is started, the control unit 1 obtains the current temperature and the target temperature and determines the duty ratio of the PWM control signal according to the current temperature, the target temperature and the heating time. It is understood that after the duty ratio is calculated, the duty ratio can be adjusted by using a PID control algorithm, so as to determine a PWM control signal with a suitable frequency, and the frequency of the PWM control signal is usually 1 KHZ. The control unit 1 transmits a PWM control signal to the detection/heating unit 4 to control the detection/heating unit 4 to warm up the steering wheel.
Fig. 3 is a structural diagram of a detection control unit according to an embodiment of the present application, and AS shown in fig. 3, the detection control unit obtains a detection signal through an AS8579 chip and implements data exchange between control units 1 through an SPI protocol. In a specific implementation, when the control unit 1 acquires the detection signal, the acquired detection signal is stored in the buffer queue. In order to further improve the accuracy of the detection result, the acquired detection signal may be preprocessed, for example: filtering (such as median average filtering) is performed on all data collected during one duty cycle.
It will be appreciated that, in order to further reduce the influence of the electrical signal in the heating circuit on the detection result, it is also possible to set the discharge phase in each operation cycle on the basis of the time-division operation of the detection/heating unit 4. In a working period, firstly executing a heating task, and entering a discharging stage to execute a discharging task after the heating task is executed; and after the discharging task is finished, controlling the detection/heating unit 4 to work to judge whether the steering wheel is out of hand.
In a specific implementation, when the detection/heating unit executes a capacitance detection task, if the second one-way conduction device is in a conduction state, the detection/heating unit is grounded, which may cause an inaccurate capacitance detection result and affect a steering wheel hands-off detection result. Therefore, it is necessary to prevent the detection/heating unit from being grounded when the capacitance detection task is performed. If the second unidirectional conducting device is a diode, a back-voltage circuit needs to be arranged at the second end of the second switching tube, and the voltage at the second end of the second switching tube is kept at a high level through a back-voltage signal provided by the back-voltage circuit. If the second conducting device is another device or apparatus capable of controlling the circuit to conduct in one direction, for example: the singlechip with the microprocessor can control the second conduction device to be switched off or input reverse voltage to the second end of the second conduction device through the singlechip when the detection/heating unit executes a capacitance detection task, so that the detection/heating unit is prevented from being grounded, and the accuracy of a capacitance detection value is ensured.
S11: and judging whether the steering wheel is out of hand or not according to the detection signal.
After acquiring the detection signal, the control unit 1 determines whether the steering wheel is in the hands-off state according to the detection signal, and the determination method is not limited herein.
Furthermore, when the steering wheel is detected to be out of hand, measures (such as alarm sending) need to be taken in time to remind a driver, and the safe driving of the vehicle is ensured.
It can be understood that the steering wheel hands-off detection circuit provided in the embodiment of the present application may further include: and the man-machine interaction unit is used for setting alarm conditions or setting the length of a working cycle and the like.
The utility model provides a steering wheel takes off one's hand detection circuitry includes: the device comprises a control unit, a first one-way conduction device, a second one-way conduction device and a detection/heating unit. The first end of the first one-way conduction device is connected with the control unit, and the second end of the first one-way conduction device is connected with the detection/heating unit; the second end of the second one-way conduction device is connected with the control unit, and the first end of the second one-way conduction device is connected with the detection/heating unit; the first one-way conduction device and the second one-way conduction device have the one-way conduction characteristic, so that the heating unit can normally work under the control of the control unit, and the electric signal is prevented from flowing into the heating control circuit when the detection/heating unit works, and the influence of the heating control circuit on the electric signal acquired by the detection/heating unit is prevented. The control unit is also connected with the second end of the first one-way conduction device and used for controlling the detection/heating unit to respectively execute tasks of acquiring a detection signal and heating at different time so as to achieve the purposes of heating the steering wheel, acquiring the detection signal sent by the detection/heating unit and judging whether the steering wheel is out of hand. Therefore, the heating control circuit signal is prevented from interfering the detection signal through the one-way conduction device, multiplexing of the detection/heating unit and the heating control unit is achieved, and the cost of the detection system is reduced on the basis of ensuring the accuracy of the detection signal and the accuracy of the hands-off detection.
It can be understood that the control unit 1 provided in the present application may be an automobile central control system, or may be a separately provided control unit 1, and the former scheme may reduce the equipment cost, and the latter scheme may realize the distributed control of each module, so as to prevent the failure of the detection/heating unit 4 due to the failure of a single module.
On the basis of the above embodiments, the steering wheel hands-off detection circuit provided in this embodiment further includes a driving unit 5, a detection control unit 6, and a switch control unit 7;
the first end of the driving unit 5 is connected with the control unit 1, and the second end is connected with the first end of the first unidirectional device;
the first end of the detection control unit 6 is connected with the control unit 1, and the second end is connected with the detection/heating unit 4;
the first end of the switch control unit 7 is connected with the second end of the second one-way conduction device 3, the second end is grounded, and the control end is connected with the control unit 1.
The scheme adopted in the embodiment is a mode of combining an automobile central control system and a drive control unit 1, the drive unit 5 is used for controlling the detection/heating unit 4 to be turned on and turned off, the detection control unit is used for controlling the detection/heating unit 4 to be turned on and executed, the detection task is stopped being executed, and the drive unit 5 and the detection control unit are controlled by the automobile central control system to work in a time-sharing mode, so that time-sharing multiplexing of a circuit is achieved, and interference of signals in a heating control circuit and coupling capacitance generated by circuit devices on hands-off detection is prevented. Further, the detecting/heating unit 4 provided in this embodiment may be a capacitive detecting film with a heating wire or a heating film resistance wire or a heating film wound on the surface thereof, and the control circuit for controlling the detecting/heating unit 4 to perform a heating task may be an MOS transistor or a circuit related to an integrated driving chip; the detection/heating unit 4 may acquire a capacitance detection signal at the steering wheel using a capacitance sensor or an integrated detection chip-related circuit.
It will be appreciated that when the heating/detection unit 4 performs a heating task, its output needs to be grounded; and the control circuit for the detection/heating unit 4 to execute the detection task and the heating control circuit multiplex part of electronic devices and circuits, and if the output end of the detection/heating unit 4 is grounded when executing the detection task, the detection signal generated by the detection/heating unit 4 cannot be transmitted to the detection control unit, which results in detection failure. In order to solve the problem, in the embodiment, the switch control unit 7 is connected to the second segment of the second unidirectional conducting device 3, the first end of the switch control unit 7 is connected to the second end of the second unidirectional conducting device 3, the second end is grounded, the control end is connected to the control unit 1, and the switch control unit 7 is turned off when the detection/heating unit 4 performs a detection task under the control of the control unit 1; when the detection/heating unit 4 performs the heating task, the switch control unit 7 is turned on. The switch control unit 7 may be a single chip controller, or may be a switching transistor, such as a MOS transistor.
Fig. 4 is a structural diagram of another steering wheel hands-off detection circuit provided in an embodiment of the present application, and as shown in fig. 4, the steering wheel hands-off detection circuit includes a control unit 1, a driving unit 5, a detection control unit 6, a switch control unit 7, a first unidirectional conducting device 2, a second unidirectional conducting device 3, and a detection/heating unit 4; wherein the driving unit 5 is used for controlling the start of the heating task and the stop of the heating task of the detection/heating unit 4. The first end of the driving unit 5 is connected with the control unit 1, and the second end is connected with the first end of the first unidirectional conducting device 2.
In specific implementation, the first unidirectional conducting device 2 is used for isolating the influence of a coupling capacitor of the driving unit 5 on the detection of the hands-off, a first end of the first unidirectional conducting device 2 is further connected with a protection resistor, and the other end of the protection resistor is grounded. In the working process, the protective resistor can provide a discharging loop when the driving unit 5 is turned off, so that the influence of leakage current of the driving unit 5 and discharging current of a coupling capacitor of the driving unit 5 on the hands-off detection is avoided, and the voltage of the first end of the first unidirectional conducting device 2 can be clamped at 0V when the driving unit 5 is turned off.
In order to ensure the accuracy of the detection signal, when the second one-way conduction device is a diode, a back voltage circuit can be connected into the hands-off detection circuit, and after the switch control unit 7 is switched off, the voltage at the second end of the second one-way conduction device 3 is clamped at a preset voltage value, so that the accuracy of the detection signal and the protection circuit are ensured. The predetermined voltage value needs to be greater than the sum of the turn-on voltages of the first unidirectional conducting device 2 and the second unidirectional conducting device 3.
It is understood that the solution provided in the present embodiment is applied to the hands-off detection circuit with only one detection/heating unit 4, and when there are a plurality of detection/heating units 4, an additional one-way conduction device may be added to extend the multi-path heating and hands-off detection.
In a specific implementation, each duty cycle of the hands-off detection circuit provided in this embodiment includes: heating stage, discharge stage and hands-off detection stage, the switching of working stage is realized to hands-off detection circuit under the control of control unit 1, and specific work flow is:
when the circuit is started, the heating stage is started: the control unit 1 acquires the current temperature and the target temperature, and determines the duty ratio of the PWM control signal according to the current temperature, the target temperature and the heating time; the control unit 1 sends the PWM control signal to the driving unit 5 to control the operation of the detecting/heating unit 4 through the driving unit 5, and the driving unit 5 may be a switching transistor (MOS transistor) or an integrated drive. Fig. 5 is a structural diagram of a driving unit provided in the embodiment of the present application, and fig. 6 is a structural diagram of a driving unit provided in the embodiment of the present application, as shown in fig. 5 and fig. 6, the driving unit 5 obtains a control signal sent by the control unit 1 through a HeatCtrl _ H1 pin, so as to control the operation of the detection/heating unit 4. Meanwhile, the control unit 1 also needs to make the switch control unit 7 conduct to form a loop, so that the detection/heating unit 4 can work normally. The switch control unit 7 obtains the control signal sent by the control unit 1 through a HeatCtrl _ L1 pin to realize on and off.
After the heating stage is finished, the discharging stage is started, and at the moment, the control unit 1 stops sending the PWM control signal to the driving unit 5 so as to stop the driving unit 5 from working; and keeps the switch control unit 7 conductive. And releasing the electric signal in the heating circuit and the electric signal of the coupling capacitor in the discharging stage so as to prevent the heating circuit from interfering with the detection result.
After the discharging stage is finished, entering a hands-off detection stage, and judging whether the steering wheel is hands off or not according to the obtained detection signal; if the hands are not taken off, entering the next working cycle; and if the driver is out of hand, sending an alarm to the driver or the remote server in time, and adjusting the running speed of the vehicle.
In the present embodiment, stability and reliability are further improved by combining the driving unit, the detection control unit, the switch control unit, and the control unit (e.g., an automobile center control system) to control the steering wheel hands-off detection circuit.
In a specific implementation, the detection/heating unit may be a capacitive detection film wound with a heating wire or a heating film, which is disposed on a surface of the steering wheel, and the heating wire or the heating film heats the steering wheel, and the capacitive detection film detects whether the driver touches the steering wheel. It is also possible to use a metal heating wire as the detecting/heating unit, and the control unit controls the metal heating wire to perform different functions in different periods, for example, to perform a capacitance detecting operation in the detecting period and a steering wheel heating operation in the heating period. Compared with the first scheme, the scheme of multiplexing the metal heating wires has lower cost. On the basis of the above-described embodiment, the detecting/heating unit 4 of the steering wheel hands-off detecting circuit is a metal heating wire provided on the surface of the steering wheel.
As a preferred embodiment, when the second one-way conduction device is a diode, it is also necessary to provide a back-voltage circuit to prevent the detection/heating unit from being grounded. In a specific implementation, the output terminal of the counter voltage circuit is connected to the first terminal of the second conducting device. The back-voltage circuit comprises a back-voltage power supply, a first resistor and a second resistor; the first end of the first resistor is grounded, the second end of the first resistor is connected with the first end of the second resistor, and the second end of the second resistor is connected with the back voltage power supply; and the common end of the first resistor and the second resistor is used as the output end of the back-pressure circuit and is connected with the second end of the second unidirectional conducting device 3.
In a specific implementation, the resistance values of the first resistor and the second resistor are determined by the back voltage power supply and the output voltage of the reaction circuit.
In this embodiment, the metal heating wire with the back-pressure circuit is used as the detection unit of the circuit to ensure that the second one-way conduction device is reversely cut off, so that the accuracy of the hands-off detection is improved, and the functions of protecting the hands-off detection circuit are achieved.
As a preferred embodiment, the driving unit provided in the present application is a PWM driving unit. In specific implementation, the control unit controls the detection/heating unit to respectively execute a heating task and a detection task at different times in a working cycle, when the heating task is executed, a heating command is sent to the PWM driving unit, after the PWM driving unit obtains the control command sent by the control unit 1, the detection/heating unit 4 is controlled to work through a PWM control signal, when the detection/heating unit 4 is started, the control unit 1 obtains a current temperature and a target temperature, and determines a duty ratio of the PWM control signal according to the current temperature, the target temperature and the heating time. It is understood that after the duty ratio is calculated, the duty ratio can be adjusted by using a PID control algorithm, so as to determine a PWM control signal with a suitable frequency, and the frequency of the PWM control signal is usually 1 KHZ. The control unit 1 transmits a PWM control signal to the detection/heating unit 4 to control the detection/heating unit 4 to warm up the steering wheel.
In this embodiment, the PWM driving unit is selected to control the detecting/heating unit to work, and the stability and reliability of the heating system can be further improved due to the strong anti-noise interference capability of the PWM signal.
In addition, this application still provides a steering wheel hands-off detection system, is applied to the vehicle, and this system still includes man-machine interaction device, communication device etc. except that including foretell steering wheel hands-off detection circuit. Since the above description is made in detail for each corresponding component, the description of this embodiment is omitted.
The utility model provides a steering wheel takes off hand detecting system, take off hand detection circuitry including above-mentioned steering wheel, this circuit includes: the device comprises a control unit, a first one-way conduction device, a second one-way conduction device and a detection/heating unit. The first end of the first one-way conduction device is connected with the control unit, and the second end of the first one-way conduction device is connected with the detection/heating unit; the second end of the second one-way conduction device is connected with the control unit, and the first end of the second one-way conduction device is connected with the detection/heating unit; the first one-way conduction device and the second one-way conduction device have a one-way conduction characteristic, the heating unit can work normally under the control of the control unit, and when the detection/heating unit works, the electric signal is prevented from flowing into the heating control circuit, and the heating control circuit is prevented from influencing the electric signal acquired by the detection/heating unit. The control unit is also connected with the second end of the first one-way conduction device and used for controlling the detection/heating unit to respectively execute tasks of acquiring a detection signal and heating at different time so as to achieve the purposes of heating the steering wheel, acquiring the detection signal sent by the detection/heating unit and judging whether the steering wheel is out of hand. Therefore, the heating control circuit signal is prevented from interfering the detection signal through the one-way conduction device, multiplexing of the detection/heating unit and the heating control unit is achieved, and the cost of the detection system is reduced on the basis of ensuring the accuracy of the detection signal and the accuracy of the hands-off detection.
It is right above the utility model provides a steering wheel takes off hand detection circuitry and system introduces in detail. 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 in the embodiment corresponds to the method disclosed in the embodiment, so that the description is simple, and the relevant points can be referred to the description of the method part. It should be noted that, for those skilled in the art, without departing from the principle of the present invention, the present invention can be further modified and modified, and such modifications and modifications also fall within the protection scope of the appended claims.
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 circuit, comprising:
the device comprises a control unit, a first one-way conduction device, a second one-way conduction device and a detection/heating unit, wherein the detection/heating unit is an integrated unit integrating a capacitance detection function and a heating function;
the first end of the first one-way conduction device is connected with the control unit, and the second end of the first one-way conduction device is connected with the detection/heating unit;
the second end of the second one-way conduction device is connected with the control unit, and the first end of the second one-way conduction device is connected with the detection/heating unit; the control unit is further connected with the second end of the first one-way conduction device and used for controlling the detection/heating unit to respectively execute tasks of acquiring a detection signal and heating at different time so as to achieve the purposes of heating the steering wheel and judging whether the steering wheel is out of hand or not according to the detection signal sent by the detection/heating unit.
2. The steering wheel hands-off detection circuit according to claim 1, further comprising a drive unit, a detection control unit, a switch control unit;
the first end of the driving unit is connected with the control unit, and the second end of the driving unit is connected with the first end of the first one-way conduction device;
the first end of the detection control unit is connected with the control unit, and the second end of the detection control unit is connected with the detection/heating unit;
and the first end of the switch control unit is connected with the second end of the second one-way conduction device, the second end of the switch control unit is grounded, and the control end of the switch control unit is connected with the control unit.
3. The steering wheel hands-off detection circuit according to claim 2, wherein the detection/heating unit is a metal heating wire provided on the surface of the steering wheel.
4. The steering wheel hands-off detection circuit of claim 1, further comprising a back-pressure circuit comprising a back-pressure power source, a first resistor, and a second resistor;
the first end of the first resistor is grounded, the second end of the first resistor is connected with the first end of the second resistor, and the second end of the second resistor is connected with the back voltage power supply;
and a common end of the first resistor and the second resistor is used as an output end of the inverse voltage circuit and is connected with a second end of the second unidirectional conducting device.
5. The steering wheel hands-off detection circuit of claim 1, wherein the first and second unidirectional conducting devices are both diodes.
6. The steering wheel hands-off detection circuit according to claim 2, wherein the switch control unit is a MOS transistor.
7. The steering wheel hands-off detection circuit of claim 2, wherein the driving unit is a PWM driving unit.
8. The steering wheel hands-off detection circuit according to claim 1, further comprising a protection resistor, wherein a first end of the protection resistor is connected to a first end of the first one-way conduction device, and a second end of the protection resistor is grounded.
9. The steering wheel hands-off detection circuit of claim 3, wherein the detection control unit is a capacitive sensor.
10. A steering wheel hands-off detection system comprising a steering wheel hands-off detection circuit according to any of claims 1 to 9.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202220592352.0U CN217435702U (en) | 2022-03-17 | 2022-03-17 | Steering wheel hands-off detection circuit and system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202220592352.0U CN217435702U (en) | 2022-03-17 | 2022-03-17 | Steering wheel hands-off detection circuit and system |
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| Publication Number | Publication Date |
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| CN217435702U true CN217435702U (en) | 2022-09-16 |
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|---|---|---|---|
| CN202220592352.0U Active CN217435702U (en) | 2022-03-17 | 2022-03-17 | Steering wheel hands-off detection circuit and system |
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| Country | Link |
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| CN (1) | CN217435702U (en) |
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