Lead screw angle detection method of electric door opening mechanism

Abstract

The invention discloses a lead screw angle detection method for an electric door opening mechanism, and the method comprises the following steps: S1, fixing an angle magnetic ring on a lead screw, enabling the central point of the angle magnetic ring to coincide with the axis of the lead screw, arranging a first Hall sensor and a second Hall sensor at the radial outer side of the angle magnetic ring according to the installation constraint condition of the sensor, the first Hall sensor and the second Hall sensor are positioned in a magnetic induction plane of the same pair of magnetic poles of the angle magnetic ring; s2, calculating the rotation angle of the angle magnetic ring through an angle algorithm; and S3, the rotation angle theta of the angle magnetic ring serves as the rotation angle of the lead screw. According to the method for detecting the angle of the lead screw of the electric door opening mechanism, the core technology bottleneck in a low-cost angle detection scheme is ingeniously solved through the innovation of combination of software and hardware, and a more perfect solution is provided for achieving high-performance motion control in cost-sensitive application.

Description

Technical Field

[0001] This invention relates to a method for detecting the screw angle of an electric door opening mechanism, belonging to the field of door motion control and angle detection. Background Technology

[0002] Currently, in smart home and consumer electric door systems, such as smart refrigerator doors, automatic cabinet doors, electric curtains, smart door locks, and electric display cabinets, it is usually necessary to accurately detect the opening and closing angle of the door or opening mechanism in order to realize the motor start / stop control and position protection strategy in the electric door control system.

[0003] Existing electric door opening mechanisms typically use a motor to drive a lead screw and a slider, which in turn pushes the door open and close automatically via a linkage mechanism. In these door control systems, it's necessary to detect the angle of the lead screw's rotation. The mainstream solution for high-precision angle detection is to use an integrated magnetic encoder. These encoders integrate a Hall array and a dedicated ASIC chip, enabling them to directly output high-resolution angle data. Their advantages include high accuracy, ease of use, and strong anti-interference capabilities. However, a significant drawback is their high cost. The bill of materials (BOM) cost, including multi-channel sensors and dedicated chips, makes them unsuitable for the highly competitive home appliance and consumer electronics markets, creating a contradiction between "performance overkill" and "cost overrun."

[0004] To reduce costs, the industry has proposed using discrete linear Hall sensors in conjunction with magnetic rings. An ideal layout is an orthogonal layout, where the physical positions of the two linear Hall sensors are precisely designed so that the phase difference between their output electrical signals is 90°. Under this condition, the classic arctangent algorithm, θ = arctan(V1 / V2), can be directly used for calculation; the algorithm is simple and efficient.

[0005] However, in actual industrial design and production, this ideal orthogonal layout faces serious challenges: 1. Space constraints: In compact product structures (such as near refrigerator door hinges), there is often not enough space to meet the precise physical layout required to achieve a 90° phase difference.

[0006] 2. Tolerance Sensitivity: Achieving a 90° phase places extremely high demands on the installation position of the linear Hall sensor, the magnetic field uniformity of the magnetic ring, and its coaxiality. Assembly tolerances during the manufacturing process, individual differences in components, and mechanical wear after long-term operation can all cause the phase to deviate from 90°, leading to a sharp increase in the error of traditional algorithms.

[0007] 3. Inconsistent Amplitude and Bias: Due to the different magnetic field strengths of the two linear Hall sensors and manufacturing differences, the amplitude (sensitivity) of their output signals and the DC bias voltage are usually inconsistent. This introduces severe harmonic errors into the arctangent calculation, resulting in periodic fluctuations in the angle calculation.

[0008] Therefore, achieving low-cost, high-precision lead screw rotation angle detection remains a challenge in this field. Summary of the Invention

[0009] The technical problem to be solved by this invention is to overcome the shortcomings of the prior art and provide a method for detecting the screw angle of an electric door opening mechanism. Through the innovation of combining software and hardware, the core technical bottleneck in the low-cost angle detection scheme is cleverly solved, providing a more complete solution for achieving high-performance motion control in cost-sensitive applications.

[0010] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: A method for detecting the lead screw angle of an electric door opening mechanism, comprising the following steps: Step S1: Fix the angle magnetic ring on the lead screw, so that the center point of the angle magnetic ring coincides with the axis of the lead screw. Set the first Hall sensor and the second Hall sensor on the radial outside of the angle magnetic ring according to the sensor installation constraint conditions. The first Hall sensor and the second Hall sensor are located in the magnetic induction plane of the same pair of magnetic poles of the angle magnetic ring. Step S2: Calculate the rotation angle of the magnetic ring using an angle algorithm; Step S3: Take the rotation angle θ of the angular magnetic ring as the rotation angle of the lead screw.

[0011] Furthermore, both the first Hall sensor and the second Hall sensor are linear Hall sensors.

[0012] Furthermore, the sensor installation constraints are as follows: The vertical projection of the center point O of the angle magnetic ring onto the mounting plane of the first Hall sensor and the second Hall sensor is O'. The distance from the center point of the mounting position of the first Hall sensor to O' is d1, the distance from the center point of the mounting position of the second Hall sensor to O' is d2, the distance from the center point O of the angle magnetic ring to O' is D, and OO' is the vertical axis. If d1≠d2, then d1 and d2 satisfy: Where N is the number of pole pairs of the angle magnetic ring, N≥1, and N is an integer; The magnetic field strength at the first Hall sensor and the second Hall sensor ranges from 10 Gs to 10000 Gs. The distance between the center point of the first Hall sensor installation location and the center point of the second Hall sensor installation location is ≥3.0mm.

[0013] Furthermore, the sensor installation constraints are as follows: The vertical projection of the center point O of the angle magnetic ring onto the mounting plane of the first Hall sensor and the second Hall sensor is O'. The distance from the center point of the mounting position of the first Hall sensor to O' is d1, the distance from the center point of the mounting position of the second Hall sensor to O' is d2, the distance from the center point O of the angle magnetic ring to O' is D, and OO' is the vertical axis. If d1 = d2, then d1 and d2 satisfy: , where N is the number of pole pairs of the angular magnetic ring, N≥1, and N is an integer.

[0014] Furthermore, step S2 specifically includes the following steps: Step S21: Construct the lead screw angle model; Step S2: Perform sum and difference processing on the output voltage V1 of the first Hall sensor and the output voltage V2 of the second Hall sensor to obtain a sum signal and a difference signal. Calculate the rotation angle of the angle magnetic ring based on the sum and difference signals.

[0015] Furthermore, step S21 specifically includes the following steps: The angle between the mounting position of the first Hall sensor and the vertical axis OO' is α1, and the formula for calculating the angle α1 is: α1 = arctan(d1 / D); The angle between the installation position of the second Hall sensor and the vertical axis OO' is α2, and the formula for calculating the angle α2 is: α² = arctan(d² / D); Let the rotation angle of the angular magnetic ring be θ, then the output voltage V1 of the first Hall sensor and the output voltage V2 of the second Hall sensor satisfy: ; Wherein, A1 is the maximum amplitude of the voltage collected by the first Hall sensor minus the bias voltage Aoffset1, and A2 is the maximum amplitude of the voltage collected by the second Hall sensor minus the bias voltage Aoffset2. Normalizing A1 and A2 to A, we get: .

[0016] Furthermore, the expression for the sum signal V_sum is as follows: ; Wherein, V1 is the output voltage of the first Hall sensor, V2 is the output voltage of the second Hall sensor, A is the normalized value of A1 and A2, θ is the rotation angle of the angular magnetic ring, α1 is the angle between the installation position of the first Hall sensor and the vertical axis OO', and α2 is the angle between the installation position of the second Hall sensor and the vertical axis OO'.

[0017] Furthermore, the expression for the difference signal V_diff is as follows: ; Wherein, V1 is the output voltage of the first Hall sensor, V2 is the output voltage of the second Hall sensor, A is the normalized value of A1 and A2, θ is the rotation angle of the angular magnetic ring, α1 is the angle between the installation position of the first Hall sensor and the vertical axis OO', and α2 is the angle between the installation position of the second Hall sensor and the vertical axis OO'.

[0018] Furthermore, in step S2, the rotation angle of the angular magnetic ring is calculated based on the sum and difference signals, specifically including the following steps: The expressions for the sum signal V_sum and the difference signal V_diff are derived as follows: V_sum = 2A • cos(θ + (α2 - α1) / 2) • cos((α1 + α2) / 2); V_diff = 2A • sin(θ + (α2 - α1) / 2) • sin((α1 + α2) / 2); Divide the difference signal V_diff by the sum signal V_sum. The expression for V_diff / V_sum is as follows: V_diff / V_sum = tan(θ + (α2 - α1) / 2) • tan((α1 + α2) / 2); The rotation angle θ of the angle magnetic ring is calculated using the expression V_diff / V_sum. The formula for calculating the rotation angle θ of the angle magnetic ring is as follows: θ = arctan[ (V_diff / V_sum) • cot((α1 + α2) / 2) ] - (α2 - α1) / 2; Substituting V1 and V2 into the formula for calculating the rotation angle θ of the angular magnetic ring, the final expression for the rotation angle θ of the angular magnetic ring is obtained.

[0019] Furthermore, the final expression for the rotation angle θ of the angular magnetic ring is as follows: .

[0020] By adopting the above technical solution, the present invention has the following beneficial effects: 1. This invention uses only two inexpensive linear Hall sensors to perform high-precision lead screw angle detection. The subsequent stage only needs to be equipped with a general-purpose MCU chip for data processing, analysis and control, which completely replaces the expensive integrated magnetic encoder, greatly reduces BOM cost, and has extremely low hardware cost, making it suitable for mass-produced home appliances.

[0021] 2. The algorithm of this invention completely eliminates the dependence on symmetrical or orthogonal sensor layouts. Engineers can arrange sensors arbitrarily according to the actual structure, greatly simplifying mechanical design, reducing the requirements for assembly precision, and providing extremely high design freedom.

[0022] 3. This invention effectively eliminates errors caused by individual sensor differences (sensitivity, bias) and magnetic field inhomogeneity through innovative parameter self-calibration and signal normalization processes. Even under non-ideal conditions, it can ensure the accuracy and consistency of measurements, and has excellent precision and robustness.

[0023] 4. The core calculation formula of this invention does not involve complex calculations. After pre-calculating constants, the real-time calculation workload is extremely small, making it perfectly suitable for low-cost MCU chips with limited resources, without requiring dedicated DSP or FPGA chips. The algorithm is efficient and easy to implement.

[0024] 5. The algorithm of this invention can compensate for changes caused by certain mechanical tolerances and wear (which can be achieved through periodic recalibration), thereby improving the long-term stability and reliability of the product. Attached Figure Description

[0025] Figure 1 This is a flowchart of the lead screw angle detection method for the electric door opening mechanism of the present invention; Figure 2 This is a schematic diagram showing the positions of the angle magnetic ring and the two Hall sensors in the electric door opening mechanism of the present invention; Figure 3 This is a schematic diagram showing the installation of the lead screw, angle magnetic ring, and two Hall sensors in the electric door opening mechanism of the present invention; Figure 4 This is a schematic diagram showing the installation of the two Hall sensors in the electric door opening mechanism of the present invention. Detailed Implementation

[0026] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0027] like Figure 1As shown in the figure, this embodiment provides a method for detecting the lead screw angle of an electric door opening mechanism, which includes the following steps: Step S1, as follows Figure 3 , 4 As shown, the angle magnetic ring 1 is fixed to the lead screw 4, with the center point of the angle magnetic ring 1 coinciding with the axis of the lead screw 4. A first Hall sensor 2 and a second Hall sensor 3 are set radially outside the angle magnetic ring 1 according to sensor installation constraints. The first Hall sensor 2 and the second Hall sensor 3 are located within the magnetic induction plane of the same pair of magnetic poles of the angle magnetic ring 1. In this embodiment, both the first Hall sensor 2 and the second Hall sensor 3 are linear Hall sensors.

[0028] The installation positions of the first Hall sensor 2 and the second Hall sensor 3 need to meet the sensor installation constraints to prevent the installation positions of the first Hall sensor 2 and the second Hall sensor 3 from being too far away from the angle magnetic ring 1, which would cause the first Hall sensor 2 and the second Hall sensor 3 to fail to sense the angle magnetic ring 1.

[0029] like Figure 2 As shown, the vertical projection of the center point O of the angle magnetic ring 1 onto the mounting plane of the first Hall sensor 2 and the second Hall sensor 3 is O'. The distance from the center point of the mounting position of the first Hall sensor 2 to O' is d1, the distance from the center point of the mounting position of the second Hall sensor 3 to O' is d2, the distance from the center point O of the angle magnetic ring 1 to O' is D, and OO' is the vertical axis. There are two cases of sensor mounting constraints in this embodiment: Case 1: If d1 ≠ d2, then d1 and d2 satisfy: Constraint 1: Wherein, N is the number of pole pairs of the angle magnetic ring 1, N≥1, N is an integer, and the angle magnetic ring 1 in this embodiment has two pairs of s poles and n poles, that is, N=2; Then, by calculating using the above formula, we obtain: .

[0030] Constraint 2: The magnetic field strength at the first Hall sensor 2 and the second Hall sensor 3 ranges from 10 Gs to 10000 Gs. As shown in Table 1, this embodiment experimentally analyzed the detection accuracy under different magnetic field strengths.

[0031] Table 1

[0032] Constraint 3: The distance between the center point of the first Hall sensor 2 and the center point of the second Hall sensor 3 is ≥3.0mm. This constraint ensures that the two Hall sampling points are located in the magnetic induction plane of the same magnetic pole, avoiding angle calculation errors and signal aliasing. As shown in Table 2, this embodiment experimentally analyzed the detection accuracy at different distances.

[0033] Table 2

[0034] Case 2: If d1 = d2, that is, the projected positions of the first Hall sensor 2 and the second Hall sensor 3 relative to the center point of the angle magnetic ring 1 are offset by the same distance, then d1 and d2 satisfy: Where N is the number of pole pairs of the angle magnetic ring 1, N≥1, and N is an integer. In this embodiment, the angle magnetic ring 1 has two pairs of s poles and n poles, i.e., N=2.

[0035] Step S2: Calculate the rotation angle of the magnetic ring 1 using an angle algorithm, specifically as follows: Step S21: Construct the lead screw 4-angle model: Depend on Figure 2 From the geometric relationships in the diagram, we can see that: The angle between the installation position of the first Hall sensor 2 and the vertical axis OO' is α1, and the formula for calculating the angle α1 is: α1 = arctan(d1 / D); The angle between the installation position of the second Hall sensor 3 and the vertical axis OO' is α2. The formula for calculating the angle α2 is: α² = arctan(d² / D); Let the rotation angle of the angle magnetic ring 1 be θ. Then the output voltage V1 of the first Hall sensor 2 and the output voltage V2 of the second Hall sensor 3 satisfy: ; Where A1 is the maximum amplitude of the voltage collected by the first Hall sensor 2 minus the bias voltage Aoffset1, and A2 is the maximum amplitude of the voltage collected by the second Hall sensor 3 minus the bias voltage Aoffset2; since V1 and V2 are sine curves, but the midpoint of the sine curve is not 0, there is an offset value, namely the bias voltage.

[0036] Based on the calibration process (rotating angle magnetic ring 1 at least one revolution), the ratio of the two maximum voltage amplitudes is calculated. Since the amplitudes of the two sine curves are inconsistent, it is necessary to calculate the ratio of these two maximum voltage amplitudes. Normalizing A1 and A2 to a single value A yields: .

[0037] Step S2: Perform sum and difference processing on the output voltage V1 of the first Hall sensor 2 and the output voltage V2 of the second Hall sensor 3 to obtain a sum signal and a difference signal. Calculate the rotation angle of the angle magnetic ring 1 based on the sum and difference signals. The expression for the signal V_sum is as follows: ; The expression for the difference signal V_diff is as follows: ; Wherein, V1 is the output voltage of the first Hall sensor 2, V2 is the output voltage of the second Hall sensor 3, A is the normalized value of A1 and A2, θ is the rotation angle of the angle magnetic ring 1, α1 is the angle between the installation position of the first Hall sensor 2 and the vertical axis OO', and α2 is the angle between the installation position of the second Hall sensor 3 and the vertical axis OO'.

[0038] By deriving the expressions for the sum signal V_sum and the difference signal V_diff, the derived expressions for the sum signal V_sum and the difference signal V_diff are as follows: V_sum = 2A • cos(θ + (α2 - α1) / 2) • cos((α1 + α2) / 2); V_diff = 2A • sin(θ + (α2 - α1) / 2) • sin((α1 + α2) / 2).

[0039] Taking the derivation of the sum signal V_sum as an example: The original formula is: .

[0040] Applying the cosine sum formula Here, let: x = θ - α1; y = θ + α2.

[0041] Calculate (x+y) / 2 and (xy) / 2: (x+y) / 2=((θ-α1)+(θ+α2)) / 2=(θ+α2-α1) / 2=θ+(α2-α1) / 2; (xy) / 2=((θ-α1)-(θ+α2)) / 2=(-α1-α2) / 2=-(α1+α2) / 2.

[0042] Substitute the calculation result into the original formula for V_sum: .

[0043] Because the cosine function is an even function, i.e., cos(-a) = cos(a), therefore: V_sum = 2A • cos(θ + (α2 - α1) / 2) • cos((α1 + α2) / 2).

[0044] Dividing the difference signal V_diff by the sum signal V_sum, the expression for V_diff / V_sum is as follows: V_diff / V_sum = tan(θ + (α2 - α1) / 2) • tan((α1 + α2) / 2).

[0045] The rotation angle θ of the angle magnetic ring 1 can be solved using the expression V_diff / V_sum. The formula for calculating the rotation angle θ of the angle magnetic ring 1 is as follows: θ = arctan[ (V_diff / V_sum) • cot((α1 + α2) / 2) ] - (α2 - α1) / 2.

[0046] Substituting V1 and V2 into the formula for calculating the rotation angle θ of the angle magnetic ring 1, we obtain the final expression for the rotation angle θ of the angle magnetic ring 1, which is as follows: .

[0047] Step S3: Since the angle magnetic ring 1 is fixed on the lead screw 4 and the center point of the angle magnetic ring 1 coincides with the axis of the lead screw 4, the angle magnetic ring 1 and the lead screw 4 rotate synchronously. Therefore, the rotation angle of the lead screw 4 is the rotation angle θ of the angle magnetic ring 1.

[0048] The specific embodiments described above further illustrate the technical problems, technical solutions, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for detecting the angle of a lead screw of an electric door opening mechanism, characterized by, It comprises the following steps: Step S1, fixing the angle magnetic ring on the lead screw, making the center point of the angle magnetic ring coincide with the axis of the lead screw, setting the first and second Hall sensors on the radial outside of the angle magnetic ring according to the sensor installation constraint condition, the first and second Hall sensors are located in the same pair of magnetic pole magnetic induction plane of the angle magnetic ring; Step S2, calculating the angle of the rotation of the angle magnetic ring through the angle algorithm; Step S3, taking the rotation angle θ of the angle magnetic ring as the rotation angle of the lead screw.

2. The method of claim 1, wherein: The first and second Hall sensors are linear Hall sensors.

3. The method of claim 1, wherein the angle of the screw is detected by a sensor. The sensor installation constraint condition is: The vertical projection position of the center point O of the angle magnetic ring on the installation plane of the first and second Hall sensors is O', the distance from the installation position center point of the first Hall sensor to O' is d1, the distance from the installation position center point of the second Hall sensor to O' is d2, the distance from the center point O of the angle magnetic ring to O' is D, and OO' is the vertical axis; If d1≠d2, then d1 and d2 satisfy: where N is the number of pole pairs of the angle magnet ring, N > 1, N is an integer; The magnetic field strength range at the first and second Hall sensors is 10Gs-10000Gs; The distance between the installation position center point of the first Hall sensor and the installation position center point of the second Hall sensor is ≥3.0mm.

4. The method of claim 1, wherein the method further comprises: determining a position of the door based on the angle of the screw. The sensor installation constraint condition is: The vertical projection position of the center point O of the angle magnetic ring on the installation plane of the first and second Hall sensors is O', the distance from the installation position center point of the first Hall sensor to O' is d1, the distance from the installation position center point of the second Hall sensor to O' is d2, the distance from the center point O of the angle magnetic ring to O' is D, and OO' is the vertical axis; If d1 = d2, then d1 and d2 satisfy: where N is the number of pole pairs of the angle magnet ring, N > 1, N is an integer.

5. The method of claim 1, wherein the angle of the screw is detected by a sensor. The step S2 specifically comprises the following steps: Step S21, constructing a lead screw angle model; Step S2, sum-difference processing the output voltage V1 of the first Hall sensor and the output voltage V2 of the second Hall sensor to obtain sum signal and difference signal, and calculating the rotation angle of the angle magnetic ring according to the sum signal and difference signal.

6. The lead screw angle detection method of the electric door opening mechanism according to claim 5, characterized by, The step S21 specifically comprises the following steps: The included angle between the installation position of the first Hall sensor and the vertical axis OO' is α1, and the calculation formula of the included angle α1 is: α1=arctan(d1 / D); The included angle between the installation position of the second Hall sensor and the vertical axis OO' is α2, and the calculation formula of the included angle α2 is: α2=arctan(d2 / D); Let the rotation angle of the angle magnetic ring be θ, then the output voltage V1 of the first Hall sensor and the output voltage V2 of the second Hall sensor satisfy: ； Wherein, A1 is the maximum amplitude of the voltage collected by the first Hall sensor minus the offset voltage Aoffset1, and A2 is the maximum amplitude of the voltage collected by the second Hall sensor minus the offset voltage Aoffset2; After normalizing A1 and A2 to A, we get: 。 7. The lead screw angle detection method of the electric door opening mechanism according to claim 6, characterized by, The expression of the sum signal V_sum is as follows: ； Wherein, V1 is the output voltage of the first Hall sensor, V2 is the output voltage of the second Hall sensor, A is the normalized value of A1 and A2, θ is the rotation angle of the angle magnetic ring, α1 is the angle between the installation position of the first Hall sensor and the vertical axis OO', and α2 is the angle between the installation position of the second Hall sensor and the vertical axis OO'.

8. The lead screw angle detection method of the electric door opening mechanism according to claim 7, characterized by, The expression of the difference signal V_diff is as follows: ； Wherein, V1 is the output voltage of the first Hall sensor, V2 is the output voltage of the second Hall sensor, A is the normalized value of A1 and A2, θ is the rotation angle of the angle magnetic ring, α1 is the angle between the installation position of the first Hall sensor and the vertical axis OO', and α2 is the angle between the installation position of the second Hall sensor and the vertical axis OO'.

9. The lead screw angle detection method of the electric door opening mechanism according to claim 8, characterized by, In the step S2, the rotation angle of the angle magnetic ring is calculated according to the sum signal and the difference signal, and specifically includes the following steps: The expression of the sum signal V_sum and the difference signal V_diff is derived, and the expression of the sum signal V_sum and the difference signal V_diff after derivation is as follows: V_sum = 2A • cos(θ + (α2 - α1) / 2) • cos((α1 + α2) / 2); V_diff = 2A • sin(θ + (α2 - α1) / 2) • sin((α1 + α2) / 2); The difference signal V_diff is divided by the sum signal V_sum, and the expression of V_diff / V_sum is as follows: V_diff / V_sum = tan(θ + (α2 - α1) / 2) • tan((α1 + α2) / 2); The rotation angle θ of the angle magnetic ring is solved according to the expression of V_diff / V_sum, and the calculation formula of the rotation angle θ of the angle magnetic ring is as follows: θ = arctan[ (V_diff / V_sum) • cot((α1 + α2) / 2) ] - (α2 - α1) / 2; V1 and V2 are substituted into the calculation formula of the rotation angle θ of the angle magnetic ring to obtain the final expression of the rotation angle θ of the angle magnetic ring.

10. The method of claim 9, wherein the angle of the screw is detected by a sensor. The final expression of the rotation angle θ of the angle magnetic ring is as follows: 。

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