Performance detection device and detection method for inductive height sensor

Abstract

The invention relates to a performance detection device and method for an inductive height sensor. The performance detection device comprises an upper computer, an MCU control unit, a servo motor, a servo driver, an angle feedback encoder, an inductive signal acquisition unit, a coil resistance measurement unit and a sensor temperature acquisition unit. The upper computer is used for issuing a control instruction and receiving and processing a feedback signal; the MCU control unit is used for sending a control instruction to the servo driver, receiving and integrating a feedback signal and feeding back the feedback signal to the upper computer; the servo driver is used for driving the servo motor to act according to the control instruction; the rotating end of the servo motor is used for installing a sensor to be detected. The device has the advantages that multi-angle automatic and accurate adjustment of the height sensor is achieved through closed-loop control of the servo motor, and posture changes in actual working conditions are effectively simulated; and meanwhile, a temperature compensation mechanism is introduced to carry out secondary correction on drift caused by self-heating and temperature drift caused by environment temperature, so that the accuracy of performance evaluation is remarkably improved.

Description

Technical Field

[0001] This invention belongs to the technical field of sensor performance testing devices, and particularly relates to a performance testing device and testing method for inductive height sensors. Background Technology

[0002] Inductive height sensors, as a type of non-contact displacement detection device, are widely used in automotive suspension systems, CNC machine tools, industrial robots, and precision assembly due to their robust structure, fast response speed, and strong resistance to contamination. They are used to monitor the relative distance (i.e., "height") between a metal target and the sensor in real time. Their working principle is based on electromagnetic induction: when a metal target approaches the sensor coil, it causes a change in the coil's inductance. This change is converted into a voltage or frequency signal output through a signal conditioning circuit, thus reflecting height information.

[0003] However, the output performance of inductive height sensors is significantly affected by changes in ambient temperature. The main reason is that the induction coil inside the sensor is usually made of copper wire, and the resistivity of copper has a significant positive temperature coefficient (approximately 0.00393 / °C). When the ambient temperature rises or the sensor itself heats up due to the excitation current, the DC resistance of the coil increases, which leads to a decrease in the coil quality factor (Q value) and a shift in the resonant frequency. This, in turn, causes a drift in the amplitude or phase of the output signal, making it impossible to properly evaluate the performance of the height sensor in very high temperature environments.

[0004] Furthermore, the output characteristics of inductive height sensors are highly sensitive to their relative attitude (especially rotation angle) with the target surface. In typical operating conditions such as car cornering and suspension movement, the sensor's working angle changes dynamically, and its sensitivity and linearity also change accordingly. However, existing detection equipment mostly uses manual adjustment or a simple rotary table for angle setting, lacking high-precision closed-loop control, resulting in large repeatability errors and the inability to achieve synchronous data acquisition at multiple angles.

[0005] Therefore, this case is brought. Summary of the Invention

[0006] The purpose of this invention is to provide a performance testing device and method for inductive height sensors, which can accurately evaluate the true performance of the sensor under various operating conditions and in a full temperature range.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] A performance testing device for an inductive height sensor includes a host computer, an MCU control unit, a servo motor, a servo driver, an angle feedback encoder, an inductive signal acquisition unit, a coil resistance measurement unit, and a sensor temperature acquisition unit.

[0009] The host computer is used to issue control commands and receive and process signals fed back by the MCU control unit;

[0010] The MCU control unit is used to send the control commands issued by the host computer to the servo driver, and at the same time receive and integrate the signals fed back from the angle feedback encoder, the inductor signal acquisition unit, the coil resistance measurement unit, and the sensor temperature acquisition unit, and feed back the integrated signal to the host computer.

[0011] The servo driver is used to drive the servo motor to move according to control commands;

[0012] The rotating end of the servo motor is used to mount the inductive height sensor to be detected.

[0013] The angle feedback encoder is used to monitor the actual rotation angle of the servo motor and provide feedback.

[0014] The inductance signal acquisition unit is used to acquire the inductance signal of the inductance height sensor and feed it back;

[0015] The coil resistance measuring unit is used to measure the coil resistance value of the inductive height sensor and provide feedback.

[0016] The sensor temperature acquisition unit is used to acquire and feed back the housing temperature of the inductive height sensor.

[0017] Furthermore, it includes an ambient temperature acquisition unit, which is used to acquire and detect the temperature of the environment and feed it back to the host computer through the MCU control unit.

[0018] Furthermore, the host computer includes a display interface, which displays at least the ambient temperature, the temperature of the inductive height sensor, the coil resistance value, the inductive signal curve corresponding to the current angle, the delete and restore buttons for the curve, the pass / fail indicator, the CAN message, and the operation prompts.

[0019] A performance testing method for an inductive height sensor based on the above-mentioned device includes the following steps:

[0020] S1. Set the target test angle sequence for the inductive height sensor under test via the host computer;

[0021] S2. Control the servo motor to rotate sequentially to each target test angle, and obtain the corresponding actual rotation angle through the angle feedback encoder;

[0022] S3. At each actual rotation angle, simultaneously collect the original inductance value, coil resistance value, ambient temperature, and inductor height sensor housing temperature of the inductor height sensor under test;

[0023] S4. Calculate the actual temperature of the coil based on the coil resistance value, and obtain the temperature deviation between the actual coil temperature and the housing temperature of the inductive height sensor;

[0024] If the temperature deviation exceeds the preset threshold, the host computer will indicate a fault in the inductive height sensor under test.

[0025] If the temperature deviation is not greater than the preset threshold, the first compensation value is obtained based on the pre-trained coil actual temperature-inductance compensation relationship model.

[0026] S5. Based on the ambient temperature, according to the pre-trained ambient temperature-inductance compensation relationship model, the second compensation value is obtained, and the final inductance value = original inductance value + first compensation value + second compensation value;

[0027] S6. Correlate the final inductance value corresponding to each angle with the actual rotation angle to generate an inductance-angle performance curve, and determine whether the sensor performance meets the preset qualification standard.

[0028] Furthermore, the formula for calculating the actual temperature of the coil is as follows:

[0029] ;

[0030] In the formula, This is the measured coil resistance value. This is the actual temperature value of the coil. Standard temperature α is the coil resistance value at standard temperature, and α is the temperature coefficient of resistance of the coil conductor material.

[0031] Furthermore, the relationship model between the actual temperature of the coil and the inductance compensation adopts a table lookup model.

[0032] Furthermore, the relationship model between ambient temperature and inductance compensation adopts a table lookup model.

[0033] Furthermore, in step S3, after the servo motor rotates to the target angle, it is necessary to wait for the preset system stabilization time before data acquisition is performed.

[0034] The advantages of this invention are as follows: It achieves automatic and precise multi-angle adjustment of the inductive height sensor through closed-loop control of a servo motor, effectively simulating attitude changes in actual working conditions and solving the problems of poor repeatability and uncontrollable angle in traditional manual adjustment. Simultaneously, a dual temperature compensation mechanism is introduced. On the one hand, the actual coil temperature is inverted in real time based on the coil's DC resistance to accurately compensate for the main drift caused by self-heating; on the other hand, the system-level temperature drift is corrected secondaryly by incorporating ambient temperature, significantly improving the accuracy of performance evaluation over a wide temperature range. The resulting inductance-angle performance curve can be directly used for qualification judgment, realizing full-process automation from data acquisition and intelligent compensation to result output. It is suitable for batch quality inspection and R&D verification in high-reliability scenarios such as automotive and industrial applications. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the architecture of the performance testing device for the inductive height sensor in the embodiment;

[0036] Figure 2 This is a flowchart of the performance testing method for an inductive height sensor in the embodiment.

[0037] Figure 3 This is a schematic diagram of the host computer display interface in the embodiment. Detailed Implementation

[0038] The present invention will be further described in detail below with reference to embodiments. It should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., used in this document indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0039] This embodiment proposes a performance testing device for inductive height sensors, such as... Figure 1 As shown, it includes a host computer, an MCU control unit, a servo motor, a servo driver, an angle feedback encoder, an inductance signal acquisition unit, a coil resistance measurement unit, a sensor temperature acquisition unit, and an ambient temperature acquisition unit.

[0040] The host computer is used to issue control commands and receive and process signals fed back by the MCU control unit. The MCU control unit sends the control commands from the host computer to the servo driver, and simultaneously receives and integrates signals from the angle feedback encoder, inductance signal acquisition unit, coil resistance measurement unit, sensor temperature acquisition unit, and ambient temperature acquisition unit, and feeds the integrated signal back to the host computer. The servo driver drives the servo motor according to the control commands. The rotating end of the servo motor is used to mount the inductive height sensor to be tested. The angle feedback encoder monitors the actual rotation angle of the servo motor and feeds it back to the MCU control unit. The inductance signal acquisition unit acquires the inductance signal of the inductive height sensor and feeds it back to the MCU control unit. The coil resistance measurement unit measures the coil resistance value of the inductive height sensor and feeds it back to the MCU control unit. The sensor temperature acquisition unit acquires the housing temperature of the inductive height sensor and feeds it back to the MCU control unit. The ambient temperature acquisition unit acquires the temperature of the detected environment and feeds it back to the MCU control unit.

[0041] like Figure 3 As shown, the host computer includes a display interface, which displays at least the ambient temperature, the temperature of the inductive height sensor, the coil resistance value, the inductive signal curve corresponding to the current angle, the delete and restore buttons for the curve, the pass / fail indicator, the CAN message, and the operation prompts.

[0042] After the detection device is prepared (wiring and power-on), the host computer sends control commands via CAN communication. The MCU control unit (using an S32K chip controller) receives the control commands from the host computer and sends a CAN signal to the servo driver to control the servo motor to rotate to the corresponding angle. The MCU control unit reads the encoder value through the CAN signal, calculates the current actual angle value, and integrates the collected inductance, temperature, and resistance signals before sending the integrated signal to the host computer. Upon receiving the integrated signal, the host computer performs temperature compensation on the inductance signal according to the temperature compensation mechanism, and then generates and displays the inductance-angle performance curve.

[0043] This device achieves automatic and precise multi-angle adjustment of the inductive height sensor through closed-loop control of a servo motor, effectively simulating attitude changes in actual working conditions and solving the problems of poor repeatability and uncontrollable angles in traditional manual adjustment. The biggest innovation lies in the introduction of a dual-temperature compensation mechanism for inductance correction. The reason for introducing this mechanism is that the output performance of the inductive height sensor is significantly affected by temperature, but its temperature drift has a dual nature, and single-temperature compensation cannot completely eliminate the error: On the one hand, when the sensor is working, the excitation current generates Joule heat through the copper coil, causing the coil housing temperature to be significantly higher than the ambient temperature. Since the inductance value is sensitive to coil temperature, relying solely on ambient temperature cannot accurately reflect the main drift caused by this local heat source. Therefore, it is necessary to measure the coil resistance in real time to invert its actual temperature and perform the first-level compensation accordingly. On the other hand, even if the coil temperature has been compensated, changes in the external ambient temperature will still affect the sensor performance, causing additional systematic offsets. This type of drift is unrelated to coil self-heating, so a second-level independent compensation based on ambient temperature is required. Therefore, this embodiment constructs a dual-path collaborative compensation mechanism of "coil temperature + ambient temperature" to accurately correct for two types of temperature drift sources: internal self-heating and external environment, thereby achieving high-precision and repeatable performance evaluation under the full temperature range and multiple posture conditions.

[0044] The specific detection method of the detection device, which includes a temperature compensation mechanism, is referenced. Figure 2 This includes the following steps:

[0045] S1. Set the target test angle sequence of the inductive height sensor under test through the host computer, such as 0°, 10°, 20°, ..., 90°, or non-uniformly distributed angles such as −15°, 0°, +15°, etc., to simulate different installation postures in actual use.

[0046] S2. Control the servo motor to rotate sequentially to each target test angle, and obtain the corresponding actual rotation angle through the angle feedback encoder.

[0047] S3. At each actual rotation angle, simultaneously acquire the original inductance value, coil resistance value, ambient temperature, and inductor height sensor housing temperature of the inductive height sensor under test. It is important to note that the servo motor will generate mechanical vibration, inertial sway, or slight rebound during acceleration, deceleration, and stopping. If relevant signals are acquired immediately during these processes, noise or transient errors caused by mechanical jitter will be introduced, affecting measurement accuracy. Therefore, a system stabilization time needs to be set (typically 200 ms to 1000 ms, depending on the servo motor's inertia and mechanical damping characteristics). After the servo motor rotates to the target angle, data acquisition should only be performed after the preset system stabilization time.

[0048] S4. Calculate the actual coil temperature based on the coil resistance value, and obtain the temperature deviation between the actual coil temperature and the inductive height sensor housing temperature. The formula for calculating the actual coil temperature is as follows:

[0049] ;

[0050] In the formula, This is the measured coil resistance value. This is the actual temperature value of the coil. Standard temperature, such as 25℃. α is the coil resistance value at standard temperature (which can be obtained through experiments or by looking up a table), and α is the temperature coefficient of resistance of the coil conductor material, which can be obtained by looking up a table.

[0051] If the temperature deviation exceeds the preset threshold, the host computer will indicate a fault in the inductive height sensor under test and pause the current test process. Under normal circumstances, the coil will be slightly warmer than the casing temperature due to self-heating, but the temperature difference is usually limited. If the temperature difference exceeds the preset threshold, it is highly likely that the inductive height sensor under test is faulty, such as a loose coil connection, abnormal resistance causing severe overheating, or incorrect installation.

[0052] If the temperature deviation is not greater than the preset threshold, the first compensation value is obtained based on the pre-trained coil actual temperature-inductance compensation relationship model.

[0053] S5. Based on the ambient temperature, according to the pre-trained ambient temperature-inductance compensation relationship model, the second compensation value is obtained. Then the final inductance value = original inductance value + first compensation value + second compensation value. It should be noted that the first compensation value and the second compensation value are directional. For example, if the temperature rises, the inductance value will generally decrease, so the compensation value should be positive. Conversely, it should be negative.

[0054] S6. Correlate the final inductance value corresponding to each angle with the actual rotation angle to generate an inductance-angle performance curve, and determine whether the sensor performance meets the preset qualification standard.

[0055] In this embodiment, the relationship model between the actual coil temperature and the inductance compensation amount adopts a lookup table model, which is obtained through calibration experiments: the test or standard inductive height sensor is placed in a constant temperature environment (such as a temperature control chamber), and multiple typical temperature points (such as 0°C, 25°C, 50°C, 75°C, 100°C) are set sequentially at a reference angle. After each temperature point stabilizes, its original inductance value is measured, and the inductance value at the reference temperature (usually 25°C) is used as a benchmark to calculate the inductance drift of each temperature point relative to the benchmark. The actual coil temperature (inferred from the synchronously measured coil resistance) is paired with the corresponding inductance drift to construct a mapping relationship, and finally a lookup table model is formed.

[0056] In this embodiment, the ambient temperature-inductance compensation relationship model adopts a lookup table model, which can also be obtained through calibration experiments: Under the conditions of fixed angle and stable coil temperature (or low excitation current to ignore self-heating), the sensor under test is placed in a temperature-controlled environment, and multiple ambient temperature points are set sequentially (such as −20°C, 25°C, 60°C, 85°C). After each temperature point is fully stabilized, its original inductance value is collected, and the system-level inductance drift corresponding to each temperature point is calculated based on the inductance value at a reference ambient temperature (usually 25°C). The measured ambient temperature is paired with the corresponding drift to establish a mapping relationship, and finally a lookup table model or fitting function is formed, which is the ambient temperature-inductance compensation relationship model, used to compensate for secondary temperature drift caused by the thermal effects of circuits, structures or target objects.

[0057] The above embodiments are only used to explain the concept of the present invention, and are not intended to limit the protection of the present invention. Any non-substantial modifications made to the present invention using this concept should fall within the protection scope of the present invention.

Claims

1. A performance testing device for an inductive height sensor, characterized in that, It includes a host computer, an MCU control unit, a servo motor, a servo driver, an angle feedback encoder, an inductor signal acquisition unit, a coil resistance measurement unit, and a sensor temperature acquisition unit; The host computer is used to issue control commands and receive and process signals fed back by the MCU control unit; The MCU control unit is used to send the control commands issued by the host computer to the servo driver, and at the same time receive and integrate the signals fed back from the angle feedback encoder, the inductor signal acquisition unit, the coil resistance measurement unit, and the sensor temperature acquisition unit, and feed back the integrated signal to the host computer. The servo driver is used to drive the servo motor to move according to control commands; The rotating end of the servo motor is used to mount the inductive height sensor to be detected. The angle feedback encoder is used to monitor the actual rotation angle of the servo motor and provide feedback. The inductance signal acquisition unit is used to acquire the inductance signal of the inductance height sensor and feed it back; The coil resistance measuring unit is used to measure the coil resistance value of the inductive height sensor and provide feedback. The sensor temperature acquisition unit is used to acquire and feed back the housing temperature of the inductive height sensor.

2. The performance testing device for an inductive height sensor as described in claim 1, characterized in that, It includes an ambient temperature acquisition unit, which is used to acquire and detect the temperature of the environment and feed it back to the host computer through the MCU control unit.

3. The performance testing device for an inductive height sensor as described in claim 2, characterized in that, The host computer includes a display interface, which displays at least the ambient temperature, the temperature of the inductive height sensor, the coil resistance value, the inductive signal curve corresponding to the current angle, the delete and restore buttons for the curve, the pass / fail indicator, the CAN message, and the operation prompts.

4. A method for performance testing of an inductive height sensor based on the device described in any one of claims 1 to 3, characterized in that, Includes the following steps: S1. Set the target test angle sequence for the inductive height sensor under test via the host computer; S2. Control the servo motor to rotate sequentially to each target test angle, and obtain the corresponding actual rotation angle through the angle feedback encoder; S3. At each actual rotation angle, simultaneously collect the original inductance value, coil resistance value, ambient temperature, and inductor height sensor housing temperature of the inductor height sensor under test; S4. Calculate the actual temperature of the coil based on the coil resistance value, and obtain the temperature deviation between the actual coil temperature and the housing temperature of the inductive height sensor; If the temperature deviation exceeds the preset threshold, the host computer will indicate a fault in the inductive height sensor under test. If the temperature deviation is not greater than the preset threshold, the first compensation value is obtained based on the pre-trained coil actual temperature-inductance compensation relationship model. S5. Based on the ambient temperature, according to the pre-trained ambient temperature-inductance compensation relationship model, the second compensation value is obtained, and the final inductance value = original inductance value + first compensation value + second compensation value; S6. Correlate the final inductance value corresponding to each angle with the actual rotation angle to generate an inductance-angle performance curve, and determine whether the sensor performance meets the preset qualification standard.

5. The performance testing device for an inductive height sensor as described in claim 4, characterized in that, The formula for calculating the actual temperature of the coil is as follows: ; In the formula, This is the measured coil resistance value. This is the actual temperature value of the coil. Standard temperature α is the coil resistance value at standard temperature, and α is the temperature coefficient of resistance of the coil conductor material.

6. The performance testing device for an inductive height sensor as described in claim 4, characterized in that, The relationship model between the actual temperature of the coil and the inductance compensation adopts a table lookup model.

7. The performance testing device for an inductive height sensor as described in claim 4, characterized in that, The relationship model between ambient temperature and inductance compensation adopts a table lookup model.

8. The performance testing device for an inductive height sensor as described in claim 4, characterized in that, In step S3, after the servo motor rotates to the target angle, it is necessary to wait for the preset system stabilization time before data acquisition is performed.

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