Intelligent device for detecting road flatness

Abstract

The utility model relates to road detection technical field especially, it relates to a road flatness intelligent detection device, including main control circuit, multichannel capacitance sensor array, electromagnetic shield casing, the multichannel capacitance sensor array is by the multiple capacitive proximity sensor that is arranged in matrix, is fixed in detection device bottom, the multichannel capacitance sensor array adopts differential type measurement structure, and is equipped with the isolation drive ring between adjacent capacitive proximity sensor, the signal conditioning circuit is connected between the multichannel capacitance sensor array and main control circuit, the inertia measurement unit is connected to main control circuit, the electromagnetic shield casing covers the device, adopts the layered shielding structure, contains at least one conducting layer and a layer electromagnetic shield layer, and is connected through multipoint earthing between layers, the utility model can adopt multichannel capacitance sensor array and realize high accuracy, non -contact type measurement, and through the electromagnetic shield design, temperature compensation and attitude change compensation of the target ensure measurement stability.

Description

Technical Field

[0001] This utility model relates to the field of road inspection technology, and in particular to an intelligent road smoothness detection device. Background Technology

[0002] Road smoothness inspection is an important part of road construction and maintenance, which directly affects driving safety, comfort and road lifespan.

[0003] Traditional testing methods mainly rely on mechanical contact measurements, such as continuous flatness testers and vehicle-mounted bump integrators. These devices have drawbacks such as high mechanical wear and measurement accuracy being easily affected by the environment.

[0004] In recent years, non-contact detection technologies have been gradually applied to the field of road inspection, such as lidar and visual inspection. For example, patent CN114859372B discloses a lidar device for road smoothness detection, which uses a mobile platform to load lidar to detect road smoothness. However, the electrical structure is simple and easily affected by noise, resulting in insufficient detection accuracy.

[0005] In addition, most road detection devices, such as CN219625706U, rely on a single sensor and do not consider the interference of carrier motion, resulting in data distortion on bumpy road sections. The detection speed needs to be strictly limited, such as uniform linear motion, and the stability is poor under complex road conditions.

[0006] Existing technologies such as lidar and visual inspection often suffer from high equipment costs and are susceptible to temperature interference under different lighting conditions, leading to performance degradation.

[0007] Therefore, it is necessary to further improve a smart road smoothness detection device. Utility Model Content

[0008] The technical problem to be solved by this utility model is to overcome the existing defects and provide an intelligent road smoothness detection device. It adopts a multi-channel capacitive sensing array to achieve high-precision, non-contact measurement. Through targeted electromagnetic shielding design, temperature compensation and attitude change compensation, it ensures measurement stability and can effectively solve the problems in the background technology.

[0009] To achieve the above objectives, this utility model provides the following technical solution: an intelligent road smoothness detection device, comprising a main control circuit, a multi-channel capacitive sensing array, and an electromagnetic shielding housing;

[0010] The multi-channel capacitive sensing array consists of multiple capacitive proximity sensors arranged in a matrix and fixed to the bottom of the detection device; the multi-channel capacitive sensing array adopts a differential measurement structure, and an isolation drive ring is provided between adjacent capacitive proximity sensors; a signal conditioning circuit is connected between the multi-channel capacitive sensing array and the main control circuit.

[0011] The main control circuit is connected to an inertial measurement unit, which is used to detect the attitude change of the device and compensate for the influence of the attitude change on the measurement of the multi-channel capacitive sensing array.

[0012] The electromagnetic shielding shell covers the device and adopts a layered shielding structure, including at least one conductive layer and one electromagnetic shielding layer, with the layers connected by multiple grounding points.

[0013] Preferably, an adjustable capacitive load is connected between the isolation drive ring of the multi-channel capacitive sensing array and the signal ground to eliminate crosstalk between adjacent sensor units.

[0014] Preferably, the signal conditioning circuit includes a multiplexer analog switch, a programmable gain amplifier, and an anti-aliasing filter; the programmable gain amplifier adopts an automatic range switching design, and its gain control terminal is connected to the main control circuit.

[0015] Preferably, in the layered shielding structure of the electromagnetic shielding shell, the outer layer is a conductive plastic layer, the inner layer is a metal plating layer, and an absorbing material interlayer is provided in the middle.

[0016] Preferably, the inertial measurement unit includes a triaxial accelerometer and a gyroscope.

[0017] Preferably, the main control circuit is connected to a temperature compensation circuit to compensate for the influence of ambient temperature changes on the measurement of the multi-channel capacitive sensing array; the temperature compensation circuit includes a temperature sensor array distributed around the multi-channel capacitive sensing array and a temperature compensation algorithm solidification module.

[0018] Preferably, it also includes a power management module, which includes a lithium battery pack and a charge / discharge protection circuit.

[0019] Compared with the prior art, the beneficial effects of this utility model are:

[0020] High-precision dynamic detection capability: By combining a matrix-arranged differential capacitive sensing array with the existing bicubic spline interpolation algorithm, the effective detection resolution is improved. The differential measurement structure and isolation drive ring design effectively suppress common-mode interference and reduce crosstalk. With dynamic gain adjustment, it can adapt to complex road conditions such as dryness and water accumulation, ensuring that the signal is free from saturation distortion.

[0021] Multi-environment anti-interference design, adopting a layered electromagnetic shielding shell to achieve full-band interference shielding, especially for high-frequency penetration interference of 1-10GHz; the inertial measurement unit compensates for attitude error in real time, and the temperature compensation circuit eliminates the influence of temperature drift, comprehensively solving environmental interference problems such as vehicle vibration, electromagnetic noise, and temperature gradient, and improving data reliability under complex working conditions.

[0022] With real-time adaptive processing capabilities, the signal conditioning circuit integrates automatic range switching and anti-aliasing filtering. Combined with the real-time interpolation calculation of the main control chip's DSP core, it achieves millisecond-level dynamic response. The adjustable capacitive load actively cancels crosstalk between adjacent sensors. With the synchronous sampling of temperature and attitude data, it ensures data continuity during motion detection and avoids motion artifacts. Attached Figure Description

[0023] Figure 1 This is a block diagram of the overall structure of this utility model;

[0024] Figure 2 This is a partial schematic diagram of the signal conditioning circuit of this utility model;

[0025] Figure 3 This is a partial schematic diagram (b) of the signal conditioning circuit of this utility model;

[0026] Figure 4 This is a partial schematic diagram of the signal conditioning circuit of this utility model (c). Detailed Implementation

[0027] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application can also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0028] It should be understood that, when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or sets.

[0029] To keep the drawings concise, only the parts relevant to this invention are shown schematically in each figure, and they do not represent the actual structure of the product. Furthermore, for ease of understanding, in some figures, only one of the components with the same structure or function is schematically depicted, or only one is labeled. In this document, "one" not only means "only one," but can also mean "more than one."

[0030] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0031] Furthermore, in the description of this application, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0032] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the specific implementation methods of this utility model will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of this utility model. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0033] Please see Figure 1-3 This utility model provides a technical solution: an intelligent road smoothness detection device, including a main control circuit, a multi-channel capacitive sensing array, and an electromagnetic shielding shell;

[0034] The multi-channel capacitive sensing array consists of multiple capacitive proximity sensors arranged in a matrix and fixed to the bottom of the detection device. Specifically, in this embodiment, the multi-channel capacitive sensing array adopts a 16×16 matrix arrangement, where the diameter of a single capacitive proximity sensor is about 8mm, which is a common size in industrial applications, such as Keyence proximity sensors. According to the Nyquist criterion, the spacing between sensors must be ≤1 / 2 of the target wavelength to avoid signal aliasing and ensure complete waveform reconstruction. Therefore, the spacing between capacitive proximity sensor units is set at about 10mm, which can reconstruct road surface undulation waveforms ≥20mm.

[0035] The multi-channel capacitive sensing array adopts a differential measurement structure, with an isolation drive ring between adjacent capacitive proximity sensors. Specifically, its differential measurement structure, through symmetrically designed pairs of capacitive proximity sensors, synchronously measures differential signals, which can suppress common-mode interference and eliminate the synchronous influence of ambient temperature, humidity, electromagnetic fields, etc. on the capacitive proximity sensors. Furthermore, an isolation drive ring is set between adjacent capacitive proximity sensors. This drive ring is connected to a dedicated drive signal instead of grounding, which can effectively suppress edge electric field interference. This dedicated drive signal is generated by the main control circuit and has the same operating frequency and opposite phase as the capacitive proximity sensor. This design can actively cancel the electric field interference between adjacent sensor units, reducing crosstalk by about 50% compared to the traditional grounding method.

[0036] The main control circuit includes an interpolation accelerator, such as using a main control chip with a DSP core. In actual measurement, based on the hardware detection resolution of the multi-channel capacitive sensing array, combined with the pre-set bicubic spline interpolation algorithm in the main control chip, the effective sampling interval is reduced to 5mm, which can improve the effective detection wavelength to meet the detection requirements for wavelength unevenness in the "Highway Technical Condition Assessment Standard".

[0037] A signal conditioning circuit is connected between the multi-channel capacitive sensing array and the main control circuit. Specifically, in this embodiment, the multi-channel capacitive sensing array is connected to the signal conditioning circuit via a flexible circuit board, and the signal conditioning circuit is connected to the main control circuit via a serial peripheral interface to control the device configuration and data transmission in the signal conditioning circuit.

[0038] Furthermore, the signal conditioning circuit includes a multiplexer analog switch, a programmable gain amplifier, and an anti-aliasing filter. Specifically, the multiplexer analog switch can be an ADG726, whose on-resistance is less than 5Ω to ensure low signal attenuation. Its selection control terminal is connected to the GPIO pin of the main control chip in the main control circuit. The programmable gain amplifier adopts an automatic range switching design and can be a PGA281. Its gain control terminal is connected to the GPIO pin of the main control chip in the main control circuit, and its output terminal is connected to the ADC pin of the main control chip. This allows for automatic switching of the programmable gain amplifier's gain level, such as 0.5x, 1x, 2x, 4x, 8x, 16x, 32x, or 64x, based on the intensity of the road surface reflection signal output by the programmable gain amplifier. This addresses the issue of signal amplitude differences in capacitive proximity sensors caused by dry or wet road surfaces, improving effective resolution. For example:

[0039] When testing dry asphalt roads, if the signal is too low: if the ADC value is less than 10% of full scale, increase the gain, such as from 1x to 8x.

[0040] When encountering a waterlogged area, the signal saturates: if the ADC value is greater than 90% of full scale, reduce the gain, such as from 8x to 2x.

[0041] By keeping the ADC value within 30%-70% of its full range, it prevents signal abrupt changes such as sudden water accumulation on the road surface from causing ADC saturation distortion. Compared with the fixed gain scheme, the dynamic gain detection range is improved, and it can automatically adapt to complex road conditions.

[0042] The anti-aliasing filter can be a fourth-order Butterworth design, offering the flattest amplitude response within the passband and avoiding signal distortion. Optional models, such as the MAX7419, integrate fourth-order filtering on a single chip. Its cutoff frequency is set to match the maximum effective frequency for road surface smoothness detection. For example, in practical engineering, the effective detection frequency is typically ≤20Hz. Therefore, considering the roll-off characteristics of the anti-aliasing filter and preventing phase distortion, the cutoff frequency can be set to 100Hz, which is five times the highest detection frequency of the road surface. This design preserves complete road surface information while effectively suppressing high-frequency noise caused by engine vibration and electromagnetic interference, making it more suitable for stable detection in vehicle vibration environments compared to discrete solutions.

[0043] The main control circuit is connected to an inertial measurement unit (IMU) for detecting attitude changes of the device and compensating for the impact of attitude changes on the measurement of the multi-channel capacitive sensing array. When the detection device encounters complex road conditions and tilts, bumps, or vibrates during movement, the relative attitude of the multi-channel capacitive sensing array and the road surface will change, resulting in the measurement value containing error signals from non-road surface undulations. The IMU captures these attitude changes in real time and performs dynamic compensation through the main control circuit to eliminate motion artifacts.

[0044] Furthermore, the inertial measurement unit includes a three-axis accelerometer and a gyroscope; specifically, the inertial measurement unit can be an MPU6050 including a three-axis accelerometer and a gyroscope, and integrates a digital motion processor to calculate attitude in real time. The MPU6050 communicates via I... 2 The C interface connects to the main control chip, and the sampling frequency is set to ≥100Hz. In this embodiment, 100Hz can be used to meet the dynamic compensation requirements. The data sampling frequency of the inertial measurement unit is synchronized with the data sampling frequency of the temperature sensor array to avoid temperature drift affecting the attitude calculation. A conversion matrix between the device attitude and capacitance value is established in the main control chip. The original measurement value of the capacitance sensor array is corrected by real-time attitude data to eliminate the measurement error caused by device tilt. This allows the detection device to work when it is not completely parallel to the road surface, and the overall accuracy is improved compared to a single sensor.

[0045] Furthermore, the electromagnetic shielding shell covers the device and is located on the outermost layer of the device, completely enclosing the main control circuit, multi-channel capacitive sensing array, signal conditioning circuit, inertial measurement unit, and temperature compensation circuit to form overall protection. The electromagnetic shielding shell adopts a layered shielding structure, including at least one conductive layer and one electromagnetic shielding layer, with the layers connected by multiple grounding points. Specifically, the conductive layer forms a reflective layer through the movement of free electrons, which significantly reflects and attenuates the high-frequency electric field. The electromagnetic shielding layer consumes low-frequency magnetic field energy through magnetic domain orientation. Multi-point grounding achieves full-band interference shielding, which is specifically designed to address the characteristic of capacitive proximity sensors being susceptible to high-frequency interference.

[0046] Furthermore, in the layered shielding structure of the electromagnetic shielding shell, the outer layer is a conductive plastic layer, the inner layer is a metal plating layer, and an absorbing material interlayer is provided in the middle. Specifically, the conductive plastic layer is lighter and more corrosion-resistant than a pure metal shell, and avoids the decrease in sensor sensitivity that may be caused by a metal shell. The absorbing material interlayer absorbs penetrating interference in specific frequency bands, especially 1-10GHz, solving the problem of multiple reflections of electromagnetic waves between metal layers in traditional shielding. The inner layer of the metal plating layer forms a Faraday cage effect, isolating the internal circuit from external interference, and the use of plating does not affect the size of the equipment.

[0047] Furthermore, an adjustable capacitive load is connected between the isolation drive ring of the multi-channel capacitive sensing array and the signal ground to eliminate crosstalk between adjacent sensor units.

[0048] Specifically, each isolation drive ring is connected to the adjustable capacitive load via an independent trace. When the electric fields of adjacent capacitive proximity sensor units are coupled, the crosstalk signal is introduced into the adjustable capacitive load instead of the capacitive proximity sensor circuit through the drive ring. The adjustable capacitive load is connected to the main control chip of the main control circuit, and its capacitance value is optimized and matched according to the operating frequency so that the phase of the crosstalk signal is opposite to the effective measurement signal of the capacitive proximity sensor, thereby achieving differential cancellation.

[0049] Furthermore, the main control circuit is connected to a temperature compensation circuit to compensate for the impact of ambient temperature changes on the measurement of the multi-channel capacitive sensing array; the temperature compensation circuit includes a temperature sensor array distributed around the multi-channel capacitive sensing array and a temperature compensation algorithm solidification module.

[0050] Specifically, the dielectric constant of a capacitive sensor changes with temperature, causing measurement drift. A distributed temperature sensor array can monitor the temperature gradient of the sensing area in real time, and the temperature compensation algorithm solidification module eliminates measurement errors caused by temperature, improving data consistency. The array-style temperature sensors can capture local temperature rises at different locations on the capacitive sensing plate, such as the temperature difference between areas under direct sunlight and in shadow. The temperature compensation algorithm solidification module performs zonal calibration based on this, avoiding mechanical deformation errors caused by thermal expansion. The temperature compensation algorithm is solidified within the module and can be executed by an FPGA chip in this embodiment. Its response speed is faster than software algorithms, ensuring real-time performance during motion detection. The temperature compensation algorithm adopts a well-known existing temperature compensation algorithm.

[0051] The compensation algorithm solidification module is integrated into the main control circuit and works synchronously with the signal conditioning circuit. It can eliminate secondary interference such as amplifier gain drift and filter cutoff frequency shift caused by temperature changes.

[0052] Furthermore, it also includes a power management module, which includes a lithium battery pack and a charge / discharge protection circuit.

[0053] Specifically, the lithium battery pack is equipped with a balancing charging circuit to keep the voltage of each individual battery cell consistent and prevent overcharging or undercharging; the charging end of the charge and discharge protection circuit integrates a charging management IC with temperature monitoring; its discharge end uses a combination protection circuit formed by integrated circuit IC and MOSFET, which is connected to the main control chip to monitor the voltage of each battery cell in real time, and immediately cuts off the MOSFET when abnormal, realizing three levels of protection: overvoltage, undervoltage, and overcurrent; its voltage conversion generates a 5V / 3A main power supply through a step-down chip, and achieves step-down output through a low dropout regulator.

[0054] The integrated circuit (IC) can be a model with a built-in high-speed comparator and an independent MOSFET gate drive channel to avoid signal path delay; the optional model is DW01. The MOSFET uses a model with low gate charge to shorten the switching delay time.

[0055] The aforementioned hardware direct-connection protection architecture and high-speed component selection design enable the charging and discharging circuit to have a fast response time and meet the pulse current requirements of the multi-channel capacitive sensing array.

[0056] The working principle and application principle of this utility model are as follows:

[0057] The multi-channel capacitive sensing array operates based on the differential measurement principle. It uses a matrix of capacitive proximity sensors to synchronously detect capacitance changes caused by microscopic undulations in the road surface. The differential pairs formed by adjacent sensors effectively suppress common-mode interference by synchronously measuring differential signals. The isolation drive ring actively cancels electric field crosstalk between adjacent units by injecting an inverted drive signal.

[0058] The signal conditioning circuit achieves wide-range signal acquisition through dynamic gain control. The programmable gain amplifier automatically switches the gain level according to the intensity of the road surface reflection signal. Combined with the anti-aliasing filter, it retains the effective frequency band signal. This design enables the system to adapt to the signal amplitude difference caused by dry or wet road surfaces and avoids ADC saturation distortion.

Claims

1. A road smoothness intelligent detection device, comprising a main control circuit, a multi-channel capacitive sensing array, and an electromagnetic shielding housing, characterized in that: The multi-channel capacitive sensing array consists of multiple capacitive proximity sensors arranged in a matrix and fixed to the bottom of the detection device; the multi-channel capacitive sensing array adopts a differential measurement structure, and an isolation drive ring is provided between adjacent capacitive proximity sensors; a signal conditioning circuit is connected between the multi-channel capacitive sensing array and the main control circuit. The main control circuit is connected to an inertial measurement unit, which is used to detect the attitude change of the device and compensate for the influence of the attitude change on the measurement of the multi-channel capacitive sensing array. The electromagnetic shielding shell covers the device and adopts a layered shielding structure, including at least one conductive layer and one electromagnetic shielding layer, with the layers connected by multiple grounding points.

2. The intelligent road smoothness detection device according to claim 1, characterized in that: An adjustable capacitive load is connected between the isolation drive ring of the multi-channel capacitive sensing array and the signal ground to eliminate crosstalk between adjacent sensor units.

3. The intelligent road smoothness detection device according to claim 1, characterized in that: The signal conditioning circuit includes a multiplexer analog switch, a programmable gain amplifier, and an anti-aliasing filter; the programmable gain amplifier adopts an automatic range switching design, and its gain control terminal is connected to the main control circuit.

4. The intelligent road smoothness detection device according to claim 1, characterized in that: In the layered shielding structure of the electromagnetic shielding shell, the outer layer is a conductive plastic layer, the inner layer is a metal plating layer, and a wave-absorbing material interlayer is provided in the middle.

5. The intelligent road smoothness detection device according to claim 1, characterized in that: The inertial measurement unit includes a triaxial accelerometer and a gyroscope.

6. The intelligent road smoothness detection device according to claim 1, characterized in that: The main control circuit is connected to a temperature compensation circuit, which is used to compensate for the influence of ambient temperature changes on the measurement of the multi-channel capacitive sensing array. The temperature compensation circuit includes a temperature sensor array distributed around the multi-channel capacitive sensing array and a temperature compensation algorithm solidification module.

7. The intelligent road smoothness detection device according to claim 1, characterized in that: It also includes a power management module, which includes a lithium battery pack and a charge / discharge protection circuit.

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