Steering wheel detection circuit, control method of steering wheel detection circuit and steering wheel
By designing the steering wheel detection circuit and using diode isolation technology, the problem of the single-layer metal grid-covered steering wheel cannot be detected by hand, and effective off-hand detection and heating of the steering wheel is achieved, reducing production costs and ensuring driving safety.
Patent Information
- Application Number
- CN202510260131.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-06
- Publication Date
- 2025-06-06
AI Technical Summary
In the prior art, the use of a single-layer metal grid to cover the steering wheel cannot perform effective hand-off detection, mainly because the basic parasitic capacitance value is too large, and the smaller parasitic capacitance value formed by the palm and steering wheel cannot be detected.
A steering wheel detection circuit is designed, and the switching between the hand detection mode and the heating mode of the steering wheel is achieved through the combination of the first control unit, the second control unit, the first diode and the second diode, and the influence of technical parasitic capacitance on detection is avoided through diode isolation.
It realizes that using a single-layer metal grid to cover the steering wheel can still perform effective off-hand inspection and heating, reducing production costs and ensuring driving safety.
Smart Images
Figure CN120101840A_ABST
Abstract
Description
Technical Field
[0001] Embodiments of the present invention relate to the field of vehicle control technology, and in particular to a steering wheel detection circuit, a control method for the steering wheel detection circuit, and a steering wheel. Background Art
[0002] In the application of steering wheel heating and hand-off detection, the traditional method is to use multiple layers of metal mesh to cover the steering wheel, and use different metal mesh layers to achieve the functions of heating and hand-off detection. The coating of multiple layers of metal mesh increases the cost. If these functions are integrated on a single layer of metal mesh, new problems will arise: when the Mosfet (Metal-Oxide-Semiconductor Field-Effect Transistor) and the metal coating layer are connected in series, the basic parasitic capacitance value of the entire hand-off detection system will be very large, and the entire basic parasitic capacitance value is about nF level, while the parasitic capacitance value formed by the palm and the steering wheel is several pF, which makes it almost impossible to complete the hand-off detection. Summary of the invention
[0003] The embodiments of the present invention provide a steering wheel detection circuit, a control method for the steering wheel detection circuit, and a steering wheel, which solve the technical problem in the prior art that a single-layer metal mesh-wrapped steering wheel cannot perform hands-off detection.
[0004] An embodiment of the present invention provides a steering wheel detection circuit, the steering wheel detection circuit comprising a first control unit, a second control unit, a first diode and a second diode;
[0005] The first control unit is electrically connected to a first detection position of the steering wheel to be inspected through the first diode, the first control unit is electrically connected to a second detection position of the steering wheel to be inspected through the second diode, and the second control unit is electrically connected to the second detection position of the steering wheel to be inspected;
[0006] The steering wheel to be inspected is coated with a single-layer resistance wire grid, and the first detection site and the second detection site are arranged on the single-layer resistance wire grid;
[0007] The first control unit is used to switch between a hands-off detection mode and a heating mode of the steering wheel to be inspected;
[0008] The second control unit is used to obtain a capacitance signal of the steering wheel to be inspected, and determine whether a hands-off state of the steering wheel occurs based on the capacitance signal.
[0009] Further, the first control unit includes a control subunit, a first transistor, a second transistor and a third transistor;
[0010] The gate of the first transistor, the gate of the second transistor, and the gate of the third transistor are all electrically connected to the control subunit;
[0011] The drain of the first transistor is electrically connected to a first power source; the source of the first transistor is electrically connected to the drain of the third transistor;
[0012] The drain of the second transistor is electrically connected to the second power supply; the source of the second transistor is electrically connected to the positive terminal of the first diode; the negative terminal of the first diode is electrically connected to the first detection position of the steering wheel to be inspected;
[0013] The drain of the third transistor is electrically connected to the cathode terminal of the second diode, and the source of the third transistor is grounded; the anode terminal of the second diode is electrically connected to the second detection position of the steering wheel to be inspected.
[0014] Furthermore, the control subunit includes one of the following: an electronic control unit of the driving device where the steering wheel to be inspected is located, a micro control unit, and the second control unit.
[0015] An embodiment of the present invention further provides a control method for a steering wheel detection circuit. The steering wheel detection circuit described in any of the above embodiments executes the control method for the steering wheel detection circuit. The control method includes:
[0016] The first control unit receives a steering wheel heating instruction, and controls the steering wheel to be inspected to switch from a hands-off detection mode to a heating mode based on the steering wheel heating instruction;
[0017] The first control unit controls the steering wheel to be inspected to return to the hands-off detection mode after the heating mode is executed for a first preset time period;
[0018] The first control unit controls the steering wheel to be inspected to return to the heating mode again after executing the hands-off detection mode for a second preset time, and the two modes are repeated until the first control unit receives a stop heating instruction.
[0019] Further, before the first control unit receives the steering wheel heating instruction, the control method includes:
[0020] After the steering wheel to be inspected is powered on, the first control unit directly controls the steering wheel to be inspected to enter a hands-off detection mode;
[0021] After entering the hands-off detection mode, the second control unit obtains a capacitance signal of the steering wheel to be detected, and determines whether the hands-off state of the steering wheel occurs based on the capacitance signal.
[0022] Further, the first control unit controls the steering wheel to be detected to enter the hands-off detection mode, including:
[0023] The first control unit controls the second transistor to be turned off, the third transistor to be turned off, and the first transistor to be turned on, so that the steering wheel to be inspected enters a hands-off detection mode.
[0024] Further, controlling the steering wheel to be inspected to switch from the hands-off detection mode to the heating mode based on the steering wheel heating instruction includes:
[0025] The first control unit controls the first transistor to turn off;
[0026] After the first transistor is turned off, the first control unit first controls the third transistor to be turned on, and then controls the second transistor to be turned on, and the steering wheel to be inspected enters a heating mode.
[0027] Further, the first control unit controls the steering wheel to be inspected to return to the hands-off detection mode after the heating mode is executed for a first preset time, including:
[0028] After the heating mode is executed for a first preset time, the first control unit controls the second transistor to be turned off first, and then controls the third transistor to be turned off, so as to control the steering wheel to be inspected to enter the hands-off detection mode again.
[0029] Further, after the first control unit receives the steering wheel heating instruction, the control method further includes:
[0030] The first control unit maintains the steering wheel to be inspected in the hands-off detection mode for the second preset time period, and then executes an action of controlling the steering wheel to be inspected to switch to the heating mode based on the steering wheel heating instruction.
[0031] An embodiment of the present invention further provides a steering wheel, the steering wheel comprising the steering wheel detection circuit described in any of the above embodiments, and the steering wheel is coated with a single-layer resistance wire grid.
[0032] The embodiment of the present invention discloses a steering wheel detection circuit, a control method of the steering wheel detection circuit and a steering wheel, wherein the circuit includes a first control unit, a second control unit, a first diode and a second diode; the first control unit is electrically connected to a first detection site of the steering wheel to be detected through the first diode, the first control unit is electrically connected to a second detection site of the steering wheel to be detected through the second diode, and the second control unit is electrically connected to the second detection site of the steering wheel to be detected; the steering wheel to be detected is coated with a single-layer resistance wire grid, and the first detection site and the second detection site are arranged on the single-layer resistance wire grid; the first control unit is used to realize the switching between the hand-off detection mode and the heating mode of the steering wheel to be detected; the second control unit is used to obtain the capacitance signal of the steering wheel to be detected, and judge whether the steering wheel is in a hand-off state based on the capacitance signal. The present application isolates the first control unit from the second control unit by using two diodes, thereby avoiding the influence of the technical parasitic capacitance of the first control unit on the detection of the parasitic capacitance formed by the palm and the steering wheel, solving the technical problem that the steering wheel coated with a single-layer metal grid cannot be detected by hand-off in the prior art, and realizing the technical effect of using a single-layer metal grid to detect and heat the hand-off, thereby reducing the production cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0033] Figure 1 is a structural diagram of a steering wheel detection circuit provided by an embodiment of the present invention;
[0034] Figure 2 is a circuit diagram of a steering wheel detection circuit provided by an embodiment of the present invention;
[0035] Figure 3 The present invention provides a flow chart of a control method of a steering wheel detection circuit. DETAILED DESCRIPTION
[0036] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.
[0037] It should be noted that the terms "first", "second", etc. in the specification, claims and drawings of the present invention are used to distinguish different objects, rather than to limit a specific order. The following embodiments of the present invention can be implemented separately, or in combination with each other, and the embodiments of the present invention do not impose specific limitations on this.
[0038] Figure 1 It is a structural diagram of a steering wheel detection circuit provided by an embodiment of the present invention.
[0039] like Figure 1As shown, the steering wheel detection circuit includes a first control unit 10, a second control unit 20, a first diode D1 and a second diode D2; the first control unit 10 is electrically connected to the first detection point X1 of the steering wheel 30 to be detected through the first diode D1, the first control unit 10 is electrically connected to the second detection point X2 of the steering wheel 30 to be detected through the second diode D2, and the second control unit 20 is electrically connected to the second detection point X2 of the steering wheel 30 to be detected.
[0040] The steering wheel 30 to be inspected is covered with a single-layer resistance wire grid, and the first detection site X1 and the second detection site X2 are set on the single-layer resistance wire grid; the first control unit 10 is used to realize the switching between the hand-off detection mode and the heating mode of the steering wheel 30 to be inspected; the second control unit 20 is used to obtain the capacitance signal of the steering wheel 30 to be inspected, and determine whether the steering wheel is in a hand-off state based on the capacitance signal.
[0041] Specifically, see Figure 1 After the steering wheel 30 to be inspected is powered on, the first control unit 10 will directly control the steering wheel 30 to be inspected to enter the hands-off detection mode. At this time, the second control unit 20 will obtain the capacitance signal between the steering wheel 30 to be inspected and the driver's palm in real time. The capacitance signal is a pF level signal. The reverse bias characteristics of the first diode D1 and the second diode D2 are used to isolate the nF level basic parasitic capacitance of the first control unit 10 from the second control unit 20, and the junction capacitance of the diode is usually pF level when reverse biased, which is much smaller than the nF level capacitance in the first control unit 10. The basic parasitic capacitance in the detection system is greatly reduced, ensuring that the basic parasitic capacitance will not affect the capacitance signal to be detected, so that the driving device can detect in real time whether the driver has a hands-off state of the steering wheel during driving, thereby ensuring driving safety.
[0042] When the driver needs to heat the steering wheel 30 to be inspected, a steering wheel heating instruction is input. After receiving the instruction, the first control unit 10 keeps the steering wheel 30 to be inspected in the hands-off detection mode for a certain period of time, and then controls the steering wheel 30 to be inspected to enter the heating mode. In order to meet the reuse of the single-layer resistance wire grid, the first control unit 10 controls the steering wheel 30 to be inspected to maintain the heating mode for a certain period of time, and then controls the steering wheel 30 to be inspected to enter the hands-off detection mode again and maintains it for a certain period of time. The switching between the modes is repeated in this way, so that the heating function and the hands-off detection function of the steering wheel can be realized by laying out a single-layer resistance wire grid, thereby reducing the production cost.
[0043] The present application isolates the first control unit from the second control unit by using two diodes, thereby preventing the technical parasitic capacitance of the first control unit from affecting the detection of the parasitic capacitance formed by the palm and the steering wheel, solving the technical problem in the prior art that the steering wheel cannot be detected by covering it with a single-layer metal mesh, and achieving the technical effect of performing hand-off detection and heating using a single-layer metal mesh, thereby reducing production costs.
[0044] Figure 2 It is a circuit diagram of a steering wheel detection circuit provided by an embodiment of the present invention.
[0045] Alternatively, if Figure 2 As shown, the first control unit 10 includes a control subunit 11, a first transistor N1, a second transistor N2 and a third transistor N3. The gate of the first transistor N1, the gate of the second transistor N2 and the gate of the third transistor N3 are all electrically connected to the control subunit 11.
[0046] The drain of the first transistor N1 is electrically connected to the first power supply VDD1; the source of the first transistor N1 is electrically connected to the drain of the third transistor N3; the drain of the second transistor N2 is electrically connected to the second power supply VDD2; the source of the second transistor N2 is electrically connected to the positive terminal of the first diode D1; the negative terminal of the first diode D1 is electrically connected to the first detection point X1 of the steering wheel 30 to be inspected; the drain of the third transistor N3 is electrically connected to the negative terminal of the second diode D2, and the source of the third transistor N3 is grounded GND; the positive terminal of the second diode D2 is electrically connected to the second detection point X2 of the steering wheel 30 to be inspected.
[0047] Specifically, when the steering wheel 30 to be tested is powered on, the first control unit 10 controls the second transistor N2 to be turned off, the third transistor N3 to be turned off, and the first transistor N1 to be turned on. The cathode end of the second diode D2 is at a high level, the second diode D1 is reverse biased, the first diode D1 is reverse biased, and the basic parasitic capacitances of the first transistor N1, the second transistor N2, and the third transistor N3 are all isolated by diodes. The steering wheel 30 to be tested enters the hand-off detection mode, and the detected capacitance signal will not be affected by the basic parasitic capacitance of the transistor.
[0048] Specifically, in the hands-off detection mode, the steering wheel 30 to be inspected is in a state of repeated charging and discharging, and a loop similar to an RC circuit is formed between the steering wheel 30 to be inspected and the second control unit 10. When the driver's hand grasps the steering wheel 30 to be inspected, the capacitance C increases, the charging time increases, and the charging current changes. The second control unit 20 obtains the capacitance signal of the steering wheel 30 to be inspected based on the change in current, and thus determines whether the hands are off based on the capacitance signal.
[0049] When the first control unit 10 receives the steering wheel heating instruction, it first controls the first transistor N1 to turn off, then controls the third transistor N3 to turn on, and then controls the second transistor N2 to turn on, and the steering wheel 30 to be inspected enters the heating mode. The third transistor N3 is turned on first to make the potential of the negative terminal of the second diode D2 reach the ground. After the second transistor N2 is turned on, the high voltage of the second power supply VDD2 passes through the second transistor N2, the first diode D1, the steering wheel 30 to be inspected, the second diode D2, and the third transistor N3 to the ground, so as to avoid the high voltage passing through the steering wheel 30 to be inspected and entering the second control unit 20 when the second transistor N2 is turned on first, causing an impact on the second control unit 30 and burning the device. Therefore, the third transistor N3 is turned on first, and then the second transistor N2 is turned on. When the high voltage of the second power supply VDD2 passes through the steering wheel 30 to be inspected, the resistance wire grid is heated, so that the steering wheel 30 to be inspected is switched from the hands-off detection mode to the heating mode.
[0050] After the first control unit 10 controls the heating mode to execute the first preset time, the second transistor N2 is controlled to be turned off again, and then the third transistor N3 is controlled to be turned off, and the first transistor N1 is turned on again, and the steering wheel 30 to be inspected is controlled to return to the hands-off detection mode again to ensure driving safety. Subsequently, the first control unit 10 controls the steering wheel 30 to be inspected to return to the heating mode again after the hands-off detection mode executes the second preset time, and the two modes are repeated until the first control unit 10 receives a stop heating instruction.
[0051] It should be noted that, without violating driving safety monitoring, the first preset time and the second preset time can be customized according to actual needs such as the heating time and the maximum heating temperature of the steering wheel 30 to be inspected, and no specific restrictions are made here.
[0052] Optionally, the control subunit 11 includes one of the following: an electronic control unit, a micro control unit, and a second control unit 20 of the driving device where the steering wheel 30 to be inspected is located.
[0053] Specifically, the control subunit 11 is used to control the on and off of the first transistor N1, the second transistor N2, and the third transistor N3 to achieve switching between the hand-off detection mode and the heating mode. The control subunit 11 can be an electronic control unit (ECU) of the driving device where the steering wheel 30 to be inspected is located, or it can be a separately set microcontroller unit (MCU). The second control unit 20 can also be directly used as the control subunit 11 for controlling the on and off of each transistor, and no specific restrictions are made here.
[0054] Figure 3 The present invention provides a flow chart of a control method of a steering wheel detection circuit.
[0055] Optionally, the steering wheel detection circuit in any of the above embodiments executes a control method for the steering wheel detection circuit, such as Figure 3 As shown, the control method of the steering wheel detection circuit specifically includes the following steps:
[0056] S101, a first control unit receives a steering wheel heating instruction, and controls a steering wheel to be inspected to switch from a hands-off detection mode to a heating mode based on the steering wheel heating instruction.
[0057] Specifically, the steering wheel 30 to be inspected will directly enter the hands-off detection mode after power-on to ensure the driver's driving safety. When the driver needs to heat the steering wheel 30 to be inspected, the driver will input the steering wheel heating command through the display panel of the driving device. After receiving the command, the first control unit 10 controls the steering wheel 30 to be inspected from the hands-off detection mode to the heating mode.
[0058] S102: The first control unit controls the steering wheel to be inspected to return to the hands-off detection mode after the heating mode is executed for a first preset time period.
[0059] Specifically, since the resistance wire grid arranged on the steering wheel 30 to be inspected is a single layer, the hands-off detection mode will stop when entering the heating mode. Therefore, for driving safety and to achieve the reuse of the single-layer resistance wire grid, the first control unit 10 controls the steering wheel 30 to be inspected to maintain the heating mode for a certain period of time, and then controls the steering wheel 30 to be inspected to enter the hands-off detection mode again.
[0060] S103, the first control unit controls the steering wheel to be inspected to return to the heating mode again after executing the hands-off detection mode for a second preset time, and the two modes are repeated until the first control unit receives a stop heating instruction.
[0061] Specifically, after controlling the hand-off detection mode to execute the second preset time, the first control unit 10 switches the hand-off detection mode to the heating mode again, and switches between the modes repeatedly, so that the heating function and the hand-off detection function of the steering wheel can be realized by laying a single-layer resistance wire grid, which saves costs and ensures safety.
[0062] On the basis of the above technical solutions, before the first control unit receives the steering wheel heating instruction at S101, the control method includes:
[0063] After the steering wheel to be inspected is powered on, the first control unit directly controls the steering wheel to be inspected to enter the hands-off detection mode; after entering the hands-off detection mode, the second control unit obtains the capacitance signal of the steering wheel to be inspected, and determines whether the steering wheel is in the hands-off state based on the capacitance signal.
[0064] Specifically, after the steering wheel 30 to be inspected is powered on, the first control unit 10 will directly control the steering wheel 30 to be inspected to enter the hands-off detection mode. At this time, the second control unit 20 will obtain the capacitance signal between the steering wheel 30 to be inspected and the driver's palm in real time, and determine whether the capacitance value represented by the capacitance signal is greater than the preset capacitance threshold, so as to determine whether the driver has taken the steering wheel off during driving.
[0065] Optionally, the first control unit controls the steering wheel to be detected to enter the hands-off detection mode, including:
[0066] The first control unit controls the second transistor to be turned off, the third transistor to be turned off, and the first transistor to be turned on, so that the steering wheel to be inspected enters a hands-off detection mode.
[0067] Specifically, see Figure 2 When the steering wheel 30 to be tested is powered on, the first control unit 10 controls the second transistor N2 to be turned off, the third transistor N3 to be turned off, and the first transistor N1 to be turned on. The cathode terminal of the second diode D2 is at a high level, and the second diode D1 is reverse biased. The current enters the first diode through the steering wheel 30 to be tested. The cathode terminal of the first diode is also at a high level, and the first diode D1 is reverse biased. The basic parasitic capacitances of the first transistor N1, the second transistor N2, and the third transistor N3 are all isolated by the diodes. The second control unit 20 detects the hand-off state of the steering wheel 30 to be tested, and the steering wheel 30 to be tested enters the hand-off detection mode, and the detected capacitance signal will not be affected by the basic parasitic capacitance of the transistor.
[0068] Optionally, S101, controlling the steering wheel to be inspected to switch from the hands-off detection mode to the heating mode based on the steering wheel heating instruction specifically includes:
[0069] The first control unit controls the first transistor to turn off; after the first transistor is turned off, the first control unit first controls the third transistor to turn on, and then controls the second transistor to turn on, and the steering wheel to be inspected enters the heating mode.
[0070] Specifically, see Figure 2 When the first control unit 10 receives a steering wheel heating instruction, based on the steering wheel heating instruction, the first transistor N1 is first controlled to be turned off, and then the third transistor N3 is controlled to be turned on, so that the potential of the negative terminal of the second diode D2 reaches the ground, to avoid the high voltage from passing through the steering wheel 30 to be inspected and entering the second control unit 20 when the second transistor N2 is turned on first, causing an impact on the second control unit 30; then the second transistor N2 is controlled to be turned on, and the high voltage of the second power supply VDD2 passes through the second transistor N2, the first diode D1, the steering wheel 30 to be inspected, the second diode D2, and the third transistor N3 to the ground, and heats the resistance wire grid when passing through the steering wheel 30 to be inspected, so that the steering wheel 30 to be inspected enters the heating mode.
[0071] Optionally, S102, the first control unit controls the steering wheel to be inspected to return to the hands-off detection mode after the heating mode is executed for a first preset time period, specifically including:
[0072] After the heating mode is executed for a first preset time, the first control unit controls the second transistor to be turned off first, and then controls the third transistor to be turned off, and controls the steering wheel to be inspected to enter the hands-off detection mode again.
[0073] Specifically, see Figure 2 After the first control unit 10 controls the heating mode to execute the first preset time, it controls the second transistor N2 to turn off first, then controls the third transistor N3 to turn off, and then turns on the first transistor N1 to control the steering wheel 30 to return to the hands-off detection mode to ensure driving safety. Subsequently, the first control unit 10 controls the steering wheel 30 to return to the heating mode after the hands-off detection mode executes the second preset time, and the two modes are repeated until the first control unit 10 receives the instruction to stop heating.
[0074] Optionally, at S101, after the first control unit receives the steering wheel heating instruction, the control method further includes:
[0075] The first control unit maintains the steering wheel to be inspected in the hands-off detection mode for a second preset time period, and then executes an action of controlling the steering wheel to be inspected to switch to the heating mode based on the steering wheel heating instruction.
[0076] Specifically, in order to ensure driving safety monitoring, after receiving the steering wheel heating instruction, the first control unit 10 will keep the steering wheel 30 to be inspected in the hands-off detection mode for a certain period of time, and then switch the steering wheel 30 to be inspected from the hands-off detection mode to the heating mode.
[0077] The control method of the steering wheel detection circuit provided in the embodiment of the present invention is executed by the steering wheel detection circuit in the above embodiment. Therefore, the control method of the steering wheel detection circuit provided in the embodiment of the present invention also has the beneficial effects described in the above embodiment, which will not be repeated here.
[0078] An embodiment of the present invention further provides a steering wheel, which includes the steering wheel detection circuit in any of the above embodiments, and the steering wheel is coated with a single-layer resistance wire grid.
[0079] The steering wheel provided by the embodiment of the present invention includes the steering wheel detection circuit in the above embodiment. Therefore, the steering wheel provided by the embodiment of the present invention also has the beneficial effects described in the above embodiment, which will not be described in detail here.
[0080] In the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0081] Finally, it should be noted that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims
1. A steering wheel detection circuit, characterized in that: The steering wheel detection circuit includes a first control unit, a second control unit, a first diode and a second diode; The first control unit is electrically connected to a first detection position of the steering wheel to be inspected through the first diode, the first control unit is electrically connected to a second detection position of the steering wheel to be inspected through the second diode, and the second control unit is electrically connected to the second detection position of the steering wheel to be inspected; The steering wheel to be inspected is coated with a single-layer resistance wire grid, and the first detection site and the second detection site are arranged on the single-layer resistance wire grid; The first control unit is used to switch between a hands-off detection mode and a heating mode of the steering wheel to be inspected; The second control unit is used to obtain a capacitance signal of the steering wheel to be inspected, and determine whether a hands-off state of the steering wheel occurs based on the capacitance signal.
2. The steering wheel detection circuit according to claim 1, characterized in that: The first control unit includes a control subunit, a first transistor, a second transistor and a third transistor; The gate of the first transistor, the gate of the second transistor, and the gate of the third transistor are all electrically connected to the control subunit; The drain of the first transistor is electrically connected to the first power supply; the source of the first transistor is electrically connected to the drain of the third transistor; The drain of the second transistor is electrically connected to the second power supply; the source of the second transistor is electrically connected to the positive terminal of the first diode; the negative terminal of the first diode is electrically connected to the first detection position of the steering wheel to be inspected; The drain of the third transistor is electrically connected to the cathode terminal of the second diode, and the source of the third transistor is grounded; the anode terminal of the second diode is electrically connected to the second detection position of the steering wheel to be inspected.
3. The steering wheel detection circuit according to claim 2, characterized in that: The control subunit includes one of the following: an electronic control unit of the driving device where the steering wheel to be inspected is located, a micro control unit, and the second control unit.
4. A control method for a steering wheel detection circuit, characterized in that: The steering wheel detection circuit according to any one of claims 1 to 3 above performs a control method of the steering wheel detection circuit, the control method comprising: The first control unit receives a steering wheel heating instruction, and controls the steering wheel to be inspected to switch from a hands-off detection mode to a heating mode based on the steering wheel heating instruction; The first control unit controls the steering wheel to be inspected to return to the hands-off detection mode after the heating mode is executed for a first preset time period; The first control unit controls the steering wheel to be inspected to return to the heating mode again after executing the hands-off detection mode for a second preset time, and the two modes are repeated until the first control unit receives a stop heating instruction.
5. The control method of the steering wheel detection circuit according to claim 4, characterized in that: Before the first control unit receives the steering wheel heating instruction, the control method includes: After the steering wheel to be inspected is powered on, the first control unit directly controls the steering wheel to be inspected to enter a hands-off detection mode; After entering the hands-off detection mode, the second control unit obtains a capacitance signal of the steering wheel to be detected, and determines whether the hands-off state of the steering wheel occurs based on the capacitance signal.
6. The control method of the steering wheel detection circuit according to claim 5, characterized in that: The first control unit controls the steering wheel to be detected to enter the hands-off detection mode, including: The first control unit controls the second transistor to be turned off, the third transistor to be turned off, and the first transistor to be turned on, so that the steering wheel to be inspected enters a hands-off detection mode.
7. The control method of the steering wheel detection circuit according to claim 4, characterized in that: Controlling the steering wheel to be inspected to switch from the hands-off detection mode to the heating mode based on the steering wheel heating instruction includes: The first control unit controls the first transistor to turn off; After the first transistor is turned off, the first control unit first controls the third transistor to be turned on, and then controls the second transistor to be turned on, and the steering wheel to be inspected enters a heating mode.
8. The control method of the steering wheel detection circuit according to claim 4, characterized in that: The first control unit controls the steering wheel to be inspected to return to the hands-off detection mode after the heating mode is executed for a first preset time, including: After the heating mode is executed for a first preset time, the first control unit controls the second transistor to be turned off first, and then controls the third transistor to be turned off, so as to control the steering wheel to be inspected to enter the hands-off detection mode again.
9. The control method of the steering wheel detection circuit according to claim 4, characterized in that: After the first control unit receives the steering wheel heating instruction, the control method further includes: The first control unit maintains the steering wheel to be inspected in the hands-off detection mode for the second preset time period, and then executes an action of controlling the steering wheel to be inspected to switch to the heating mode based on the steering wheel heating instruction.
10. A steering wheel, characterized in that: The steering wheel comprises the steering wheel detection circuit according to any one of claims 1 to 3, and the steering wheel is covered with a single-layer resistance wire grid.